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DEPARTMENT OF THE INTERIOR 


MONOGRAPHS 


OF THE 


UNITED STATES GEOLOGICAL SURVEY 


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WASHINGTON 
GOVERNMENT PRINTING OFFICH 
1899 


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UNITED STATES GEOLOGICAL SURVEY 


CHARLES D. WALCOTT, DIRECTOR 


GLACIAL GRAVELS OF MAINE 


THEIR ASSOCIATED DEPOSITS 


BY 


GEORGEH H. STONE 


WASHINGTON 
GOVERNMENT PRINTING OFFICE 
1899 


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(ETT RS OF! TRANSMIE WAI. nise oels eee eee arse eet ents sa tea oe SERRE esearch eels Wensincciee cecil XIII 
CHAPTER JI.—Introduction -....-------.---- Bae BAGS pesos sis 
CHAPTER IJ.—Fundamental facts of surface eOOloay & as 5 illoesivoviadl 5 in Wiesne. SPN Mn Re eens 5 
Surface features of Maine .......-...-..--..-------- 5 
Natureroimune Poclkcay ote Mian et ce eects role rare sores 2nd ees ote elnyee ae ava Sunsmtee : 6 
Conditionvoterocksimeplacenseeeraeee eee aeer eae eee RA See EMP cee ioera cela 7 

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VWYYGEITINGIBIING coed aoc dba goon ppS Spa neOd RODS BOSN Ue tes Soe ReGMEEeEe50 pecs Ape conS sao eoSoseuees 
ihransportaLlonyandenbeldninitacenciesae-nsiesss= anaes eae eee ame seeee eee eee eeee 1 
Transportation by landslip and soil-cap movement .................--...---.----+------ 10 
Mransportatloms biyawan Certo mao etelara ios = (a\ntetatera = a sis anos See yacieieieo eee Sa ease see 11 
Dransportation bysrunninge water. -)-- 4-22. 25-5252. soos 922 eens asses sees eee se eee 13 
Sedimentation teaser s-yccyat cielo scl ene he eisai ete RIN eevee Sao eee eee tees 15 
Transportation and erosion by springs and subterranean streams 
TMT NOMA, [hy AACHEN 5550 5bn0 san Sed soserae™ non6 Senn Shonosed ssaSeno5 seco an0esdé 20 
TONS OREO, [hy WOE TIA NOS) Se doqn Gabe Sees boas voHs CehaGe Ga padede nduuas ESGadeoese oncd 21 
Shapes of drift fragments..-.........+--.------------ eee aie sa we seca 
CHAPTER IIJ.—Preliminary description of the superficial deposits of nh. 
IPaeynllexciedl CG CCSNUS) 26 soc sos cees 2525 coco sc eseo cons case onus sone 
Clagiell Ce WOMUS secsco soba tobe 6625 cook cogs oanb sasu CSUUsads boners anes <bos Sand seaa eas beaees 
“Na bl i ase seeq eed bok bones 545 cQSoC uae eee a Rene ee EoE Bee Manes uonatecsass esooceconasS 
IDG OTIC OLE TWN) WH, ao ceo ssoe noe eeo Seas Sona secs ses 
hekupperandel owe tabi Resear ase eee eee eee eae aee eee 
Sediments transported by glacial streams ....--..--..--..------------- 
Marine deposits and geological work of the sea .-.......-..----- 
Beach and cove gravels....-.---..----.---------- 
Fossils in the raised beaches 
Sandsrandvelaysier temas aaa is Sa cid oe cree erelahis e hee ects Seer bin Sle ERE etc eae Ba rte 
The lower clays—deltas deposited by glacial streams..-..-.......-.-.---.--------- 
The upper clays—deltas deposited by ordinary rivers ....-..--.---- 
SWUNG, soos cone Soe onsoed S09 cess obes BSSO GES SaSS Se50SSe5 6560 Hoes Ho Doce ones Sscesces 
Valley Gatti sccs caso son Soon co00 S000 Gas seco BuaH Sco cbble so Heb esas Beco ds08 C605 S00 SacaTS 
River terraces ....-.-....-.-.- acon 2590 eda s0a0 cond Dcacar 000 GbS0 D0nS=0 co00 coos oe onnese 61 
Recent erosion of the valley alluvium and of the glacial sands and gravels 
Origin of the higher river terraces of the valley drift 
QUDTTITEIAT aoe6 cobs coda ta soeces C564 SSE D Oden BES DheCOO SSSR BRU REE ase 3 C 
CuHaprer TV.—General description of the sqetomns of@placialicravelsieseeeeeeeneEeeeeee ree eeee 70 
WEI GO KORG ENSUE ob 55 5500 ponb CHM RRORS A CORR HEB aadiconedoaiaas Hood cose sass SecmeeoHGeae 
Dyer Plantation system ......-.....-.---.---- 
Baring-Pembroke system ...-.......-.-------- “SCS ee 
Houlton-Dennysville system............-.---.-------+---+--------- 
New Limerick-Amity branch ...........-..--.---.-:------- 
Smyrna-Danforth branch 
ligllenaG! IE) HANA <5 coco aa os Seo song 5008 Se59 bape cess oso Seon coes God nese oe beSaeS 
ocalyxamespiny Mani one eee eerie ele eee a1 eee 
Bast’ Machias system) --..-------..------=------------- 
Crawiordisy stem ses macs |see seas i-in2 5 one wie oe.~ si sin ieee eee se seen 
Wilderness region north of Columbia, Columbia Falls, and Jonesboro ....---...----.-- 
Wiesley_Nonthitiel disyStemy nema vacriais-(e/teisiet elm «lane iat ee eee et ae re eee 90 
Topsfield-Old Stream system........--....-.---.-.---.--- so dedinpecs esos pacaueos se 90 
Grand Wakeosare.s-/--ieec)- seine = see se ee eek oe 
Harmi@ overeraviels)s-..-)- 22ers. see eee 


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VI CONTENTS. 


Cuaprer IV.—General description of the systems of glacial gravels—Continued. 
Bancroft-Grand Lake system -.-..-------------------------------------- +--+ ------+---- 
Sisladobsis-Pleasant River system-.--.. ---- -------. ------------------------------------- 
Seboois-Kingman-Columbia system ---. --------.-------------------------------------- 

Winn-Lee gravels --..------------ ---- +--+ ---- ---- -- ++ 2222 + oo ee eee eee es eee ee 
Katahdin system .-.-.---.------------ +--+ ---- +--+ +--+ --- + = 722 222 oe ee eee ee eee 
Staceyville-Medway branch -....--..--.------------------------------------------ 
Shifmnom Singseiid EINE 4255 ooo2 coco e522 sce seeses sone coos se S305 SSeS seer sese 
Sam Ayers Stream branch .-....--.-.------------------------------- 
Milinoket Lake-Howland branch -.--.---------------. ---.------_.---.-----.------ 
Soper Brook gravels ---.--...----------------------------------------------------- 
Note on the upper Penobscot Valley -..--- -.---------------------------- .------------- 
Eastbrook-Sullivan system --..-----..----- ---- ------ = 2 <= 5 2-2 = nnn = = ee - 
Minor gravel series. ~~ 22 =~. one one a Sees 
Wioeiln WienerenAulle EVEN 3-5 sss5 Goes so6s endo saoees coee se cre eben secu SseS ose Soa sSee5" 
Wess MiGpmin ll WSS Os-- 5c. os 554 + ssocec sosees sese seco sse555 2Ssese do5ses osce aces 
Team keal Wining QARGHS |. - 5-2 scenes ce seS5 seen oe econ oecone Sane S250 sosess seosessecr 
(CiitgigM=A LEMANS) CHEWED, soos sees deeds seageosrcess sap ees ssacds Cogses ose cnesussase 
Local eskers northwest of Ellsworth........-...---..-.--.----.----+-----------+-- 
Ts@Gleyn- Orda! yO. ns SocSas sosess Sse ssssse onsses SES SSE ssosac SosSse S25 Sesssse= 
Wis elenyél WANs SYNE — one = 355 255552 so sess seen sa00 298 S696 3555 555656 955s 550555 2558 
WieGhtonsl-Talemayyelein OSHIP. 5- oa < ease 5s cece see ses cesses ose sscesrss seers eessoorTe= 
MI@OEEINEHIG! ILANKG) CRBIP. coe 254 Sacase + sede deeses bosdes tooes ssc ssesed oossc0cc02 SoSs 
Kenduskeag-Hampden branch .-----..---.-----.-------------------------+--------- 
TDeiae Milena ANON, ooo 56> osa55 spose seocess coseeo snes corse sasssoserseere 

DO WIGS; OEE ccoeetcanenm oS05 soe aco pec ee Soe asd Saso US ss sesecesegecersesesosens sdeces 
Ronen WRabyere OS? .5 222.5522 seesesoseos+ cece cota bees soos soos ooeros ssecss Seco osenas = 
Ikan Iba \WWVOrIS Orso 5 ce aa cone cone soa0 seeo Joedes ress sosaedoSos uns sss cose cose 
ily ayy \\inllhornenM ne OSA? 55526522 520s Sessa s0esos Sans socso2 Jssa 2Saoe2 Sasa ceeess= 
TDN GMAT) SAVE. sooo Sees setts oooSs soe 2ese Gosose Jastee sosssoscoessogesesosse cos: 
Local eskers in Jackson 
Waldo-Belfast Bay system 
IBTOOKS SE .6 likeli yj UC 0 eee ee 
Local eskers in Dexter 
Corinna-Dixmont system 
East Troy kames 

ESE O yes. © LESS US iS a 
Wigraoihlnseybmeyy Bey EMME coscee coe ae one dee sooo cone sooo een oeeese seooteSsecarseese 
General noteonstiherbelfast recion ssa ease eens eee eee eee e eee een 
Local eskers in Troy and Plymouth 
GeoreesiRiv erisysbemeessseeae eae ee sae eee ee ee ee 
Hartland-Montville system 
Summarys -j322: <a eset ence Os oe cores See ee ree eer eee ee eee eee ee ee eee 
Cambridge-Harmony gravels 
IPalermo=NViaLlenys ySve DN eer eke etal eee 
Short eskers in Waldoboro 
MedomaciValley systems <2). 2eetsea eae erect eer Cer ee ene eee eee eee eee 
Local gravels in Nobleboro and Jefferson 

Dy erswRiverisystem =<. 22210 see eee see eae ee eee eee eee eee ee eee 
South Albion-China system 
Clinton-Alna system 
Albion branch 


lower Kennebec Valley system’ 2 2e2e. == ose eee eee ae eee eee ees eee ener 
Short eskers south and southwest of Moosehead Lake 
Locai eskers in Richmond and Bowdoinham .........-....---.---.-------.-------- 
Sedimentary drift of the upper Kennebec Valley 


CONTENTS. 


CHAPTER IV.—General description of the systems of glacial gravels—Continued. 
AIS QI -IIAGIROM SOVES= cons cess cose cece sees esas 226 S06 Sooceo Seades oes ace sa0gue SoSens ctan 
Norridgewock-Belgrade system .......--.----------------------------++---------+----- 
Worth Pomel RAMEN socs0 cessed soc0 cosSae ca59 0n09 coosSe sacees Sods oSO0ES BeOS eSEa6 
Mercer-Belgrade branch .......-...----. ---------- ++ +--+ ------ +--+ 2222-2 2222 oe 
Late glacial history of the upper Kennebec Valley .---..-.----- .----.-------------- 
Short eskers in Manchester and Litchfield..........-.-.-.---------------.--------- 
Ibi NTEIGLB@yGlomN EYP 5 S2es5 sasccesso0 Se0ge4 s6n6 2520 9500 s25c bn0S55 0009 Yoeass Sone 
Local eskers in northwestern Maine. ...-...---..-.-------------------------------- 
Dead River-Jerusalem system........---..----. .--.----.----- ------ ------ ---- --------- 
Note on the northwestern part of Maine .........--------------.------------------ 
Head fle) = Bur siya @ Kel Sy Ge De eee ee ee 
Wrayne-Monmouth) branch) 222 ese 22 eee = eee el =e 
@rarals mone Shloginia HONG oe sccss co5556 0650000058 050000 Hees 05000550 505509 S25005 
IWi@uHaNR WEIGM GEG cocace anaace eooens so98e5 con eas bosuos sosasabses60 Ss5059 0005 2605 
@hestenvalllle— lee cl Sis vis te Une eee eee eee eee 
’ Freeport system .....-.------.---------------------------- ---- ------ - +--+ = +++ 222+ +--+ -- 
LOW HEO MEDINA SEMIS ca- osoece send ease cess55 35655050 540500 SeDSeaSesese ooSse5 cesSs¢ 
Hillside eskers in Jay and Wilton......-..--...----. .-...----.-------------------- 
Canton-Auburn system. Sogo ec aoss BOA C A eee neae ane cosutsad sepdde.cavasebaoosaeaconds 
Note on the Androscoggin Valley ..---..----.----------------------------+---+----- 
TamiligiGle Celkemy tin Tlewtntorrloo6 conse cqoeea esses seoSes Se seee oaes Sec tos Socean Seane 
TORTI A OTIC! RASUEN 55 cones cone soos Foss sede 660 sans chos c9ocs saan cceson Steg ssasse 
Woes SimomersawlemGl SEO 255 soce00 ss see cee 55 csc5se seossn opSees acess Hees ossssac 
Branches in Hebron and near West Minot..........-..---.---.-------------------- 
Hillside eskers in Oxford County...-..-.----.------.----------.--------------+---- 
Yarmouth-Cape Elizabeth system_.---..-----..---. .----- 22-28. 2222 ee wen ne 
Androscoggin Lakes-Portland system...---------------------------------------------- 
Kennebago kames .-..------.--.-..----. ------ ------ 2+ -- 22 = 2-2 2 2 = 
WOOkeS MNS [AMON < coos sadoso ae sous dacueo baasabieEaaes GoosSa ceo sasooE se5ase ae6s 
General note on the Portland system........-...---.--.-----.----. ---------------- 
IL@eenl Galents Tin WVERUIDROOS. 655505 Gone bees 6554 seoseo coe Ss0 sHese5 Do6e0 dodoce soeseR5 
CHS OMA\MIACIIATN AYTUEIN coos cone casa esos soe5 ce56 co5e so05 25E6 boEe Sead oda Sees Soc ossnES 
Gray-North Windham series'-....-.- ---. ---- --.- ---- - <2. ---- -+-- so <2 2- = === - = = 
General note on the glacial gravels of southwestern Maine --...---.--------------- 
Note on the basin of Sebago Lake..-.-.....-.-...-.--------------------- jee esse 
Naples-=Stamdush iSeries se s=s)-ee see eae am mee eae eo ea eater 
SRDARO EOMESs ces csccce vssses coeees ssnGes bosese Enesco os aseN casass 2523 0RoRes sSSeScace¢ 
IBPIGIU OMB MIG SENN. coo sseecs sous 25 sede 2956209050500 38555 959506 Sa55a5 Sasso Scns 
TBSilominiy MRAMCMNG 205 cascnes seas sega code pane copSco SSsbe soso o0be stac CSesde seSoso55 
IDO IEINOINGS soos co55 case sacese sages b5e555 oss ees S808 0909 5965 seas asee codSDoSS 
JN -SQeO IRRVOP GEIGSs255escosse sesseo 455550 coon as5dse 555590 950555 soca ssSses coDass 
WeltaybnanchFateNoruheyWwaberrord ese eee ae see ae eae ene een er a ali 
Alluvial terraces of the Saco River....-.----.----------.------------------------- 
Great complex of northwestern York and southwestern Oxford counties...-----..----- 
Acton=Norih) BenwiCkas ySbuerie sss lee ee ee eae eee ete = ai eee le 
TUGIDETNONS RIPSIM scan cssscocce: cose one sone 3855 ceosae 099008 Soeses FSS555 Uaases Sa5Ss05S5= 
WWVGBin ILGISRIN@M ES/HIOM, 25250 oases soon sesn so5se5 cose odes 9005 oSenG0 cess aesseqssesu5 5955 
CHAPTER V.—Classification and genesis..--...-..-.------.-----------+------------------------- 
Preglacial land surface and soils........---. .---.----------- --2--+ ------ === -------------- 
Gnapallnaal smOuy GHG! TED sess coos cman s5en os64 Heeees Sose cossse cassse cond onSSa5 essen soos¢ 
GN?) HLL, oan nolbcas eoesood deo Sde bet u Ee eRe oe see Sse ee moBe esses copods|) yebus ascnobeEeeouces 
Morainalydébnisroteshesce-sheeteessseeese= sees ee eee aee eee eee tee eee eer 
Moraine stuff the lower part of the ice.......-.--...-------.--------------------- 
WEI ObOR® MNORATIN® cose coon seoc dubs Soca eudeoe sooo olsoneon 5409 ca08 Saas cde caon case 
Moraines of Androscoggin glacier. ..-...---------.------------ BASE Ot ee En: 
Qmeminlin OF Gagleeiall GOB ssc 5scqs6 S665 5060 2950 500s seas cose sbsesccsnEedoese cos 


VIII CONTENTS. 


CuaPTeR V.—Classification and genesis—Continued. 
The till—Continued. 
Giang) MOTRIN) oo coc ceod odoces Saseee so6260 225005 oobees caobes aso s boaseDOSSeeEs DeoSa0 
ID IRWIN Coca becade sdae asae Hoedso oodses pHoDed cooeoE dbo sta no cose Rese sane neooes Sosa 
Relation! tomarine) pravels-.-- - =. 22 eee ee oe ee 
Bowlderseldsyandutrainse---- eee eee eee eee e ree EE eee eee eee eee ae eee 


Relation ofmwrabersbomul ey ool aCe Tere eee eee eee 
Sizes of the glacial rivers of Maine ...--...-.-.-----. .-..-------+--++--.--------------- 
Zones of the Maine ice-sheet. ----. Sau ceAHSse SHS bose Ha danS Shue suie Dosodere ceaceadoncus 
Lome EYGHAl SAEEINS 955-6 cos coo ssccos s2eces cassa0 Se0 2950 sons sede Sese sees sess oSbe zSSse5 
Directions of subglacial and englacial streams under existing glaciers...-..-.-.-----.- 
Internal temperatures of ice-sheets ..-......-.-.--...--.------------ +--+ ------ - +++ ---- 
Basal waivers! Ole CO=SHOC US erste eee eet a ao eee teat 
spre TARO) GS iaeeHON THObTMAVENS) ooo 5b boon S555 pS beSr concas Scoses senRas cegoss 
Genesis and maintenance of subglacial and englacial channels ...--...---..----..----. 
Donnas OF Gllag@iall CwemMMEIS) 25 cccess casos sens coaecs seeaee es sees ezsecs oscocs ssecec essed 
Extraordinary enlargements of the glacial river channels -.----.-..--.-.-------------- 
Directions of glacial rivers compared with the flow of the ice._........---..-------.-- 
Relations of glacial rivers to relief forms of the land.-..--._..-....--.---------------- 
Sedimentation in places favorable or unfavorable to the formation of crevasses --.----.- 
Glacialiniversiofe Maines Sum niatyee = see eee eee ene e eee saree eee eee ere eral 
Gllayorell OWNS oeass osceanse s50ceS 325 He ceas Goos seecas across DEeece cose sercecoseces 
Hormationiotskames/amdlosats ieee ee ase sel eee tee eee eee eee ee ieee eererl= 
Bowldersiof the olacialjomaivel see =a. eee eee ee a= ee eee ee eee 
Remarks on the glaciation of the Rocky Mountains ...-.-.-----...----.----.-------------- 
ILA IPG Hred MIO URIDINE. sooo cece aaados Hohe coteco esssso opaser sessos ososse condos soacos se 
Ibe) Amines) Wallen? soScec Sane s2aace S656 22.5520 co be copoau ee sinnS cocesosospes ono sees eesda 
Whoyseie Lem@ Creaels Weilllley7o- cone sosccs conoes soso pes cam ban ss0 Saeeen soNSSe csecoF crea secuE 
\Weillesy OF ne Sein Wilemell inyGiRossecce2 Socss oceans cope or ooon esos Joceso secs oss see05 
Valley, of the) Uncompahsre River] - == ems eee a= eee ae 
Whajose Amenagas WaNlley7- 2525 s2gsc0 ssaceoeScces cose sean cone peeses osoeos cabese oSeana soee 
Tense Letepy ke INNS. sok once SoeesaESHo moc cade coe see oaceso.ceno secees coco sees etecuD 

South Park .-.-- ee ee OE eS cee einen PN Eo Gao Babes SoS OLE Adoe 
IRophahyew Mie aa sue ver ass Senn ace socosaecoobSHors coddeshoos con coed usec nopueswane 

INOS SK Ob Wate eo paisoas eseoobEedasoos seed pobeca cea ose WoonbccesobDde Soon coseso cond.sene 

Bistes: Parke: fee paca be acces oe eae eRe eee tae eae eter terete 

\yelilexy Oe wing) Sep benern IinyGre, UGS. 8 os soe oso esto cdoc Sans concos osdSed oo Deos ceoOES 
NUGME DG erae esos poe odS O4Ge SaOnERAora Shah caetas ane ocosuonS oseneoabecoee Seancedns 

Gleonell MAP sco coeeeececcescnocssoss ceesse sees] ssebes oppeSs cscs casesensEsces 
Siainbh eee emecas acid aabeOobbiaScoucuoCognce cosuidoDl.obs6 moog suse cooauelnecses on0E 
General summary of the Rocky Mountain region. .....-...----.----------------------- 
Glaciers:of-Allaska.- =. ~~. /2 sa gescicer ese oer oa Pere ene eee eee see ee eae eee ere 
Overwashlaplons=s25 eee eee eine eee eee eee nee eee Ee Eee eeeee ene ne eeceeeiee rer 
Osaristreains and) osare! ica 2ees oS seth ccna e ao ne ee ae ee See eee eee oeiee eer 
CHAPTER VI.—Classification of the glacial sediments of Maine.-.... .----.-.------------------ 
Jeary WAAR 3 oes Gos Ses o565s0 HoS546 SdQ 600 sancdS < boo eas CoseUs SoeSSE SocosuEDeS DOES 
INEINVeR CG ooSke coaseen so poe cose ap pbs cea coesmk ceoenn apo ocoosHesa conn! Uncsed eocmod sncoeeS 
Glacial gravels as modified by the sea -.-.........--.-------.-----.----. .----. -------- 
Short isolatedosansorleskers -. -=-2)nqssmne> een saa seco ieee aise eee ee eee Cee eee eee 
1S TUNES CREWS) OI SIRENS) + 5555 cacesossoc00 one e56 G50D0S SncEESpONT6c doena> MsogEs CDMS SS DoSSEaS 
Isolated kames or short eskers ending in marine deltas ---. .- IG J AS SL a Re 
Isolated osar-mounds or massives not ending in marine deltas proper -..--.-.----.----------- 
Glacialmarineideltas.. j.5. sa2-)-+ sees eres Creer Chee ee eee eee eee eee aera 


CONTENTS. Ix 


CHaPTER VI.—Classification of the glacial sediments of Maine—Continued. Page. 
Systems of discontinuous osars ----.----------------------. ------------------------------- 376 
Glacial gravels of the coastal region ---...-.------------------------+------------+------- 379 
Relations of glacial gravels to the fossiliferous marine beds ---..----..------------ 379 
Lenticular shape of the coastal gravel masses .-..-.---.---.-----.---------------- 382 
Decrease of glacial gravels toward the coast..---....----------------------------- 386 
SUTIN, oasso9 seseco sod a40 ceeto0 255565 sagoed aoc sos oN Seas ooSeSe SonSaos6ess3 so5e08 389 
Retreatal phenomena. --- --- <2 2 on a ee ee ee miami 390° 
Causes of noncontinuous sedimentation within ice channels....... .--.-.-----.-------- 395 
Résumé: History of the coastal gravels ......----.-.--. .----------+---------------------- 403 
Late glacial history of the coastal region --....-..........-------------------------------- 409 
SWTNIAIAT costco conse cceese cosS5e oes Sns Poeees saddas sesase cossas odaoCaneosse Sscec6 411 

OER cons cece coonee Seon songs CadEeD Sooons BE80 Sodans danSs6 bean soso Sods dons Soceoe Beas aSsceD 413 
Comparison of continuous with discontinuous osars -.--....-..------------------------ 416 
Were osars deposited by subglacial or by superficial streams?...... .-...-.------.------ 420 
ILGINGHANOI!. THOR soos Hoao eROUIe due BEaH OSA Tee oe SeetteE tee eo cae Cadeee Ubanbe saoaoLeteS 421 

Angie of lateral slope of the ridges-------- =< = 2. 2222) 2-2 nn nn 493% 
Tinta HUAMCMMNG - 56 sso5sc so ecee sess cos seceso cssase Se ccos code sage Seesoe ose ae86 423 
M@mmeleiningys OF WEEE ooses ene cee cboces a2 sons see Ses ce Sons opseso cooDsS sesces assas 425 
Pinnacles or elongated cones ----.-.--.-.-.----.----- ---------- ------------------- 426 

Broad and massive enlargements ....-.--.....-.--------------. ------------------- 497 
Teermomllen rer! wake} 55 ooo oe6 cogd becoce Saas Sb bo eSees0 sen Geog sSe0 3655655550 5555 5506 427 
Probable velocities of the two kinds of streams. -....-..-...-..--------.----..----- 428 
Erosion of the ground moraine ........-..----. -------------------- +--+ -++--------- 429 

Gaps in the osars....-...---- ---- ---- ---- +--+ ------ ---2-+ ------ ------ =--- ~~~ ----- 430 

Si7@ OIE WOO CEH so5e soso oaen a900 p90 058586 Go500e Sansa so00e8 Oacaa0 CoSoaS AesaeuaES 431 

Local versus far-traveled material .........-..----..------------------------------ 431 
Phenomena of glacial rivers in crossing hills and valleys ---.....------------------ 433 

TEROAGL OSHINS GP OSENE WOMIACS ac = p05 coaces cose soee cee 0Sc0 ssoees conc assSsemsccsccessecseccoo | §= HMO 
Formation of the broad osar channels. .-...--.-----------. ---------------------------- 444 
IRamioullaiaal @lkers OF WANES 222s cassee ososne cose cose sadsbe sooEse ose SHecos Sesdse cesses cose 448 


Ways in which a ridge of aqueous sediment can be formed ..--..------------..-------- 451 
Formation of kettleholes and other basins inclosed by ridges or by plains of aqueous 


RGUAG MIS sooo coca Cocos Goes Sowa Ss eS eOs Cob OES GaN coo SoecaaOaeaoa Oded Saenes Sees 5059 453 
Origin of the glacial gravel complex and its relation to marine and lacustral deltas-... 455 
Plexus situated at one end of a marine glacial delta. ......-.-....----------.------ 455 
Reticulated ridges at the proximal ends of the glacial lacustrine deltas.--.---..--. 459 
Reticulated ridges as a part of glacial lacustrine massives -..--------..--..------- 459 
Reticulated ridges within ice channels.----.--.-.--.------------------------------ 460 
Origin of the larger complexes ...--....-.---------------------------------------- 463 
Osnm Tnomilar Cllag7 c2cc c2oc p05 acc case gadeiess Saco oe 4 bang se seco sess scasacoassqotascoscons § HGS 
Deltas deposited by glacial streams in frontal g elacial iia ade eral a sme ee eietesiaisia saris 469 
Waillagy GUaURY coo¢ aco case eas Heco 0529 9455 0908 RUa0 odos Soca saes asses peccosce qos oséececesccons | GM) 
Valley drift of purely fluviatile origin....-..--..------------------------------------- 470: 
Valley drift of semiglacial origin. ..-----.------------------------------+----+---------- 474 
Relation of the valley drift to the other glacial and marine sediments -...---.--------- 475 
TEGisiortOAlll AVAWIOME 5505 co so50 s6s5 5050 Sone Send Beae Soe Rdo cHeo GES sess bossao soECeDS 476 
Relation of the valley drift to the marine beds--....-..---.-------.---.---------------- 480: 
Former height of the sea ...-...---.--:------------------+-------------- +--+ ---------- » 481 
Causes of the relative fineness of the lower strata of the valley drift and the marine 
lnadls OF Had tantem@r Walley Scsccas soncbo 5258 S550d0 esce ra sse0 se se seasas cneees coca EsneS 485 
The lower stratum, composed of clay, a OD fine sand aeeereet ese ere else oe ea oo 
PH eCOATS ETAT PP CLyS Wl ab DLS ee ele eal SO) 


Sizes of the valley- Gln BITOTD se soem coke oe sesoee BEA A one ohne Saar Saaene epee meeasen pists” 
INDEX .... ---- ---- +--+ 2-2 = te eee eee en ee re en cee ee ee eee eee cree 497 


US RSA ONS: 


PuateE I.-Hummock of granitic till; Casco ............-.-.-----------0-+------------ =------- 
II. Preliminary map of marine clays of Maine..........-...--------------------------- 
III. 4, Lakelet surrounded by glacial gravel; Lee..........---...---..----------------- 
B, Dome of coarse gravel; Springfield ..-.--....... .------------------------------- 
IV. 4, Osar crossing Penobscot River --.-.----------..-------------------+-------------- 
B, Osar expanded to a plain; South Lincoln...-.....-...-.--.---------------------- 
VY. A, Osar forking into a double ridge ...-...---....--....----------+-+---+++-+---. ---- 
J3. Visenwaloglin Ogres WiMNINGl - so o5s5c0 seose0 ce sess oe ceas as saes coS0Ss Gaon ssa s0S5 500% 
Wil, 4b lshiisin, GreriyGll TNESNV@) 0565 055058 be 5aa9 ooo a59 S8oSe6 65055 HoSons oseSsnasa5E0 SSecc= 
B, Till bowlders in glacial gravel--.-..---...-.-.---.-------.---------------------- 
VII. 4, Osar penetrating a low pass; Clifton.--..-..--.----.---------------------------- 
B, Broad osar terrace; Bucksport.-..--..------------------------------------------ 
VIII. Osar ending at the shore of Penobscot Bay; Stockton ---.--....---.---.------------ 
IX. Meandering of osar; Detroit....--...-------..------------------------------------- 
X. Hogback Mountain, looking west across south end of pass ....--.------------------ 
XI. Diverging delta branches of osar; Hogback Mountain Pass. .--------...------------ 
XII. Lenticular gravel hillock; Chima .--.--.--.---.-----------.---.--+------------------ 
XIII. Succession of three lenticular eskers, part of a discontinuous osar; Windsor -...-..- 
XIV. 4, Funnel in gravel massive; West Bowdoin .-.-...----.---.---.------------------- 
B, Ravines in gravel parallel with the direction of the glacial river; Durham .--.-.. 
XV. A, South end of a hillside esker; Jay.-..----.-------------------------------------- 
By Hallsideleskers; Hebron seseee - a= = ase en 
XVI. Broad osar penetrating a low pass; Woodstock ...---. somal obeys eeree es eee ER ere eneie 
VIL. Osar eroded by Sebago Wake-----..- ~~~ 22 2 ee oe a ee ee ee 
XVIII. Broad osar passing over high hill; Baldwin.....-.--.----------------- ---.-------- 
XIX. Till bowlders in osar; Baldwin ...-...----..-.--.------------------------ Se Se 
XX. Broad osar crossing: col’; Brownfield: -.------- ~~. 2 =~ 22 = 22228 wns nnn 
NOX. Phe Noteh;) Hiram! 2225-222 - 22-2. = ---- -5 22 22 = ee = ne 
XXII. Osars on hillsides; Newfield.......-.-...---.---..----.---------------------------- 
XXIII. 4, Plexus of kame ridges and mounds near North Acton...-....---.-----.---------- 
B, Terminal moraine; Winslows Mills, Waldoboro ...--..-...---------------------- 
XXIV. A, Section of terminal moraine _..-....-..-----..----- ------------ ------ ------ ------ 
B, Top of terminal moraine..--...----...---------- .-----+-----------: -------------- 
XXY. 4, Terminal moraine; Waldoboro.....-----.----.---------------------------------- 
B, Terminal moraine of Androscoggin glacier; Gilead..---...-.-.-----------.------ 
XXVI. A, Bare ledges in channel of glacial river; Parsonsfield -.....-.-.--.-------.--.------ 

‘ B, Osar sprinkled with till bowlders; Prospect..--.-.--..----.-----------.--------- 
XXVII. 4, Reticulated ridges of coarse water-rolled gravel; Parsonsfield-....---.---..----- 
B, Stratification of glacial marine delta; Monroe.-.--.--..------------------------ 
XXVIII. Discontinuous osar near Monroe Village ..-.-...---.------------------------------- 
XXIX. Till bowlder on glacial gravel; West Bowdoin....-...---..------------------------ 
XXX. Till bowlders on marine delta gravel; Waterboro ....---.-.--.-.----------.-------- 
XXXI. Map of Maine, showing approximately the lines of frontal retreat of the ice -.---.-- 
XOONIOL, Osis, \Witwllespeles AMOI, cossos5de6 235555 co56 e600 3590 0350 0658 cone soa sea5 Sece aaa 
SOOO, Wl Gm Tol @ERIPR WOU e455 cdosanaseceaessece Seses baeueh vedese Sano besees 
XXXIV. Reticulated kames; Porter -.......-...-----.-------------------- eae A See aes 
XXXY. Large osar bowlders on hillside ridge; Porter -.-.......-..--.-----.---------.------ 
XXXVI. A, Kettlehole in marine delta, near Monroe Village ...---...----.------------------- 
B, Lake bordered on all sides by terraces of glacial gravel; Hiram..-.-.-.---..----- 


XII ILLUSTRATIONS. 
Page 
PLaTE XXXVII. 4, Basin containing lakelet in the midst of a broad gravel plain; northern 
[OSHA OIF \NVMINGISOE Sooo oogoce seo nae cessor Sse Eee Son ooc onor OsSees soos sen oreS 454 
B, Gravel mesa; southern part of China -..............-.-...------.--------- 454 
XXXVIII. Map of Androscoggin County, showing location of glacial gravels_...--....-- 490 
XXXIX. Map of Aroostook County, showing location of glaciai gravels -......--..---- 490 
XL. Map of Cumberland County, showing location of glacial gravels .....-.--.-.- 490 
XLI. Map of Franklin County, showing location of glacial gravels -......--..-..-. 490 
XLII. Map of Hancock County, showing location of glacial gravels -.---.---..----- 490 
XLIII. Map of Kennebec County, showing location of glacial gravels ...-...-...----- 450 
XLIV. Map of Knox County, showing location of glacial gravels.......-..-.-..------ 490 
XLV. Map of Lincoln and Sagadahoc counties, showing location of glacial gravels.. 490 
XLVI. Map of Oxford County, showing location of glacial gravels .....-..---.------ 490 
XLVII. Map of Penobscot County, showing location of glacial gravels -....-.-------- 490 
XLVIII. Map of Piscataquis County, showing location of glacial gravels..--_. ....-..- 490 
XLIX. Map of Somerset County, showing location of glacial gravels.--.-..-.--.---- 490 
L. Map of Waldo County, showing location of glacial gravels ...--...---..----- 490 
LI. Map of Washington County, showing location of glacial gravels. -...-.------- 490 
LII. Map of York County, showing location of glacial gravels.....-...----.------ 490 
Fig. 1. Stratification of wind-blown sand) uockesMalls:s2 2422 se neue sasn tae conse se assees aac ae 12 
2. Section across deep lenticular sheet of till; Kents Hill, Readfield......-....-........-. 32 
3. Section across Munjoy Hill, Portland ...---.----....-.. 2-2. .-- 222 522. -2-- -5-- ---- ane 32 
4 Longinudinalisectionlohcoverace est eset sam aaa eee ee te eee eee 42 
Soubransyerse: section of seanwalllleeseeeee sel alee eee eee eee aeeee erase eee eae 43 
6. Transverse section of ancient cove gravels ........--.------ -----. ---- 22-2 22-22 eee - 45 
7. Ancient beaches sloping up from the shore -.......--..---..---.---.------------------- 46 
8. Section across terminal moraine near head of Kennebec Inlet.-.........---.---..------ 51 
9. Osar and delta-plain inclosing lakelet; Vanceboro .--.-..----..--- Suse OED Sem ieeeretars 71 
10. Osar cut by the Piscataquis River at Medford Ferry....--..----.---.------------------ 123 
diy Section of osars) evant sone 2. see ce cert sane one eee ene eiaceisesine eeeeeleee en eeeines 132 
i, }Crumplea strata near surface of osar; Kenduskeag Valley..-.--...--------.----------- 132 
14. Section across Exeter Mills-Hermon osar, in Carmel ..-.....----...---.---------------- 133 
15; Meanderin got osar;a Carmel no. oe ee eee Ea ee AC eee ee eee eee eieee eee eee eee eee 133 
NGS Osengg IRM MMI a6 6oqoeo sand sooaes Sob556 seoban one Hadess Osea SHa8 Sod osaNES CoDdce sEDEe 149 
17. Map of Hogback Mountain; Montville and vicinity .......-.-..-.--.---.---.---- Baeose 151 
18. Section across channel eroded in the till; Montville ........---..-.-..-.---.---.------- 152 
19. Reticulated ridges and Hogback Mountain, from the north. -.-....-...-----.------------ 153 
20. Section across Kennebec Valley. .-...------------ Hon abdb C509 HoGbdS Habslsdes OSes aseeoosS 176 
zt Stratification of a lenticular esker; Auburn ees 
22.5 : E peer eare t eeri a ri cy ery ee 205 
2a} IbennGlihhy ehn laren IsbUIlS JOA EWN = eoe- soo coos econ escsS cere eesesocessasseenostes = 2B) 
24, Broad osar penetrating narrow pass over hill 400 feet high; Limington...---.....-.... 258 
25. Ideal sections across channels of superficial glacial streams..--.-..----..--------------- 317 
Zea Sechionyofachitimandypothol ey wat see eee ea eee ee 328 
27. Sheet of marine clay overlying osar; Waterville ....-..........---..-----4------------ 379 
28. Marine clay overlying base of osar and itself covered with a capping of gravel; 
Corinth ese See ae ais See a eee eee ee eee 380 
29. Marine clay in the midst of osar gravel; Hermon Pond............--..-.--------------- 380 
30. Marine clay overlying base of osar; Hampden _.................----.----------+----s- 381 
31. Lenticular esker flanked with blowing marine sand; Bowdoin ...-...---..----.------- 383 
32. Ideal section of glacial-stream channels crossing transverse valleys..-.----------------- 433 
33. Section of valley between Sherman and Springfield.........:..-......----------------- 437 
34, Diagrammatic section across osar-plain; Woodstock and Milton ........--.------.----- 442 
35. Diagrammatic section across osar-plain; valley of Bog Brook, Canton ............----. 442 
36. Diagram illustrating the method of finding the highest sea level in an interior valley.. 482 


Lic BIR QUE TIAN SNOT A I. 


University or Curcaco, 
Chicago, June 13, 1894. 

Sir: I have the pleasure of transmitting a report by Prof. George H. 
Stone on The Glacial Gravels of Maine and their Associated Deposits. 

The value of this elaborate report upon one of the most remarkable 
of the phenomena connected with the Ice age needs no comment in this 
connection. : 

Very respectfully, yours, 
T. C. CHaMBERLIN, 


Geologist in Charge. 
To the Director, 


United States Geological Survey. 


XIII 


THE GLACIAL GRAVELS OF MAINE AND THEIR 
ASSOCIATED DEPOSITS. 


By Grorce H. Srone. 


OHA Te Meas Jes 1b 
INTRODUCTION. 


This investigation was begun in the summer of 1876, and has been 
prosecuted during vacations. The report was substantially completed in 
June, 1889. Vhe work was much embarrassed by the lack of sufficiently 
accurate maps, those available warranting only a reconnaissance and an 
approximate location of the kames, osars, ete., im relation to the roads, 
streams, and other features shown. The true relation of the glacial gravels 
to the relief forms of the land can be shown only on topographical maps, 
and the full delineation of the magnificent kame and osar systems of 
Maine is therefore left to the topographer and geologist of the future. 
In certain parts of the State, especially in the wooded regions, the work 
is not complete, but it can be confidently claimed that all the longer 
systems and the more common types of formation are here described. 

The investigation made slow progress, not only because there were 
several thousand miles to be carefully explored, but especially because the 
nature of the subject renders such an investigation exceedingly difficult. 
The scout of the Western frontier who undertakes to guide a body of 
troops in pursuit of hostile Indians—to follow the trail, and, from the traces 
left behind, to give a history of the enemy’s performances from day to 
day—has a difficult task before him; but in thus reconstructing history he 
has the advantage of knowing, from direct observation, the habits of the 
Indians. In his study of glacial deposits the glacialist labors under the dis- 
advantage of not knowing, by observation, the exact nature of the geolog- 


ical work going on beneath and within an ice-sheet. It is comparatively 
MON XxxIv——l1 1 


2 GLACIAL GRAVELS OF MAINE. 


easy to theorize regarding the probable behavior of such a body of ice, 
and, if properly held in check, imagination is of the greatest use in such 
an investigation, but the chances for error are very great. ‘The method 
here adopted has been to collect as large a body of facts as possible, and 
then carefully to.test various hypotheses by the facts, rejecting or holding 
in abeyance all theories not supported by positive field evidence. Glacial- 
ists are exploring a comparatively untrodden field, and it behooves them 
to proceed cautiously and to avoid dogmatism and denunciation. 

This report is intended to apply only to Maine, and is not a history of 
the progress of glacial science. For present purposes, therefore, it is not 
necessary to refer in detail to the many reports and articles which have 
been written on the subject of the water-assorted glacial drift of North 
America. 


Chronological list of works treating of the glaciology of Marne. 


BAILEY, J. W. Account of an excursion to Mount Katahdin, in Maine. Am. Jour. 
Sci., 1st series, vol. 32, 1837, pp. 20-34. Drift phenomena, pp. 26, 33-34. 

JACKSON, Charles T. First report on the geology of the State of Maine. Augusta, 
WS, G5 WT joo : 

Second report on the geology of the State of Maine. Augusta, 1838. 8° 168 pp. 

Third annual report on the geology of the State of Maine. Augusta, 1839. 8°. 
Pp. 1-276, i-lxiv. 

[Also two reports on the geology of the Wild Lands (1839), largely duplicative 
of the above works. | 

[Bowlders and diluvial scratches in Maine. Discussion.] Am. Jour. Sci., 1st series, 
vol. 41, 1841, p. 176. 

[Glacial drift.] Am. Jour. Sci., Ist series, vol. 45, 1843, pp. 320-324. Reference to 
drift in Maine. 

Hirencock, C. H. General report upon the geology of Maine. In sixth annual 
report of the secretary of the Maine board of agriculture (Augusta, 1861, 8°), 
pp. 146-328. Superficial deposits, pp. 257-288. Includes letter from John 
De Laski concerning effects of glacial action on Vinalhaven. 

Geology of the Wild Lands. Im sixth annual report of the secretary of the 
Maine board of agriculture (Augusta, 1861, 8°); Part II, Physical geography, 
agricultural capabilities, geology, botany, and zoology of the Wild Lands in 
the northern part of the State, pp. 331-458. Geology, pp. 377-442, including 
remarks on glacial drift. Geological map opposite p. 377. 

Geology of Maine. In seventh annual report of the secretary of the Maine 
board of agriculture (Augusta, 1862, 8°); Part II, Reports upon the geology 
of Maine, pp. 223-430. Surface geology, pp. 377-401. Glacial phenomena 
described, pp. 378-391. This report includes a letter from John De Laski on 
“Ancient glacial action in the southern part of Maine,” pp. 382-388. 


PUBLICATIONS. 3) 


Hotmes, Ezekiel. Geology of a portion of Aroostook County, Maine. In seventh 
annual report of the secretary of the Maine board of agriculture (Augusta, 
1862, 8°); Part Il, Reports upon the geology of Maine, pp. 223-430. Letter 
from Dr. Holmes to Prof. C. H. Hitchcock, geologist, pp. 359-376. Neference 
to drift phenomena. 

De LAsS«KI, John. Ancient glacial action in Maine. In seventh annual report of the 
secretary of the Maine board of agriculture (Augusta, 1862, 8°); Part II, 
Reports upon the geology of Maine, pp. 223-430. Letter to Prof. C. H. Hiteh- 
cock, geologist, pp. 382-388. Also in Am. Jour. Sci., 2d series, vol. 36, 1863, 
pp. 274-276. 

Deg LAskKi, John. Glacial action about Penobscot Bay. Am. Jour. Sci., 2d series, 
vol. 37, 1864, pp. 335-344. 

PackARD, A.S. Results of observations on the drift phenomena of Labrador and 
the Atlantic coast southward. Am. Jour. Sci., 2d series, vol. 41, 1866, pp. 30-32. 
Maine, pp. 31, 32. 

WHITTLESEY, Charles. On the ice movements of the Glacial era in the valley of the 
St. Lawrence. Am Ass. Ady. Sci., Proc., vol. 15, 1866, part 2, pp. 43-54. 

PACKARD, A.S. Observations on the glacial phenomena of Maine and Labrador. 
Mem. Boston Soc. Nat. Hist., vol. 1, 1866-1869. 4°. Pp. 210-303, pls. 7-8. 

WELLS, Walter. Report of the superintendent of the hydrographic survey of Maine. 
Augusta, 1869. The water power of Maine. 

Dana, J.D. On the position and height of the elevated plateau in which the glacier 
of New England, in the Glacial era, had its origin. Am. Jour. Sci., 3d series, 
vol. 2, 1871, pp. 324-330. 

Dz LAskt, John. Glacial action on Mount Katahdin. Am. Jour. Sci., 3d series, vol. 3, 
1872, pp. 27-31. 

Dana, J.D. On the Glacial and Champlain eras in New England. Am. Jour. Sci., 
3d series, vol. 5, 1873, pp. 198-211, 217-218. Maine, 205, 206, 210. 

Hitcucocn, C. H. The geology of Portland, Maine. Proc. Am. Ass. Adv. Sci., vol. 
22, 1873, pp. 163-175. 

Hirencock, C. H. (J. H. Huntington and Warren Upham, assistants). Report on the 
geology of New Hampshire (Concord), vol. 1, 1874; vol. 2, 1877; vol. 3, 1878. 
This report contains much information as to the drift of the western border of 
Maine and the region adjacent thereto. The chapters on glacial geology are 
largely by Upham. 

SHERMAN, Paul. Glacial fossilsin Maine. Am. Naturalist, vol. 7, 1873, pp. 373-374. 

SHALER, N.S. Recent changes of level on the coast of Maine. Mem. Boston Soe. 
Nat. Hist., vol. 2, part 3, No.3. Boston, 1874. 4°. Pp. 321-340. 

PACKARD, A.S. Glacial marks on the Pacific and Atlantic coasts compared. Am. 
Naturalist, vol. 11, 1877, pp. 674-680. 

HuntIneton, J. W. Geology of the region about the headwaters of the Androscog- 
gin River, Maine. [Abstract.| Proc. Am. Ass. Ady. Sci., vol. 26, 1877, pp. 
277-286. Glacial drift, pp. 284-285. 

STONE, George H. The kames of Maine. [Abstract.| Proc. Boston Soe. Nat. Hist., 
vol. 20, 1878-1830 (Boston, 1881), pp. 430-469. 

Wricut, G. F. The kames and moraines of New England. Proe. Boston Soe. Nat. 
Hist., vol. 20, 1878-1880, pp. 210-220. 


4 GLACIAL GRAVELS OF MAINE. 


Sronz, G. H. The kames or eskers of Maine. Proc. Am. Ass. Adv. Sci., vol. 29, 
1880, pp. 510-519. 

Hamuty, C. E. Observations upon the physical geography and geology of Mount 
Katahdin and the adjacent district. Bull. Mus. Comp. Zool. Harvard Coll., vol. 
7, 1880-1884, pp. 189-223. 

Stone, George H. Apparent glacial deposits in valley drift. Am. Naturalist, vol. 15, 
1881, pp. 201-252. 

The kame rivers of Maine. [Abstract.] Science, vol. 2, 1883, p. 319. 
The kame rivers of Maine. [Abstract.] Proc. Am. Ass. Ady. Sci., vol. 32, 1883, 
pp. 234-237. 

SHALER, N. S. The geology of the island of Mount Desert, Maine. In Highth 
Annual Report of the United States Geological Survey, 1886-87, J. W. Powell, 
Director, Part II (Washington, 1889), pp. 987-1061. Surface and glacial geol- 
ogy, pp. 994-1031, with map of surface geology, p. 1060. 


Many briefer articles have been published on the subject of the Maine 
drift. Notable among these are the early writings of Agassiz on the glacial 
geology of New England, published in part in the Atlantic Monthly. 


CHAPTER II. 


FUNDAMENTAL FACTS OF SURFACE GEOLOGY AS 
ILLUSTRATED IN MAINE. 


~ In order that there may be no doubt as to the sense in which certain 
words are employed in this report, or as to the standpoint from which it is 
written, the following explanatory chapter is prefixed to the report proper. 
This is the more necessary because I have found it desirable to use some 
words in a more restricted sense than that in which they have been used 
by many in the past. 
The principal facts with which the student of the drift has to deal are 
the following: ; 
SURFACE FEATURES OF MAINE. 


The surface features of the regions penetrated by the several systems 
of glacial gravel will be described in connection with the gravels. It is 
therefore not necessary here to give any detailed description of the topo- 
graphical features of the State. A few remarks will sutftice. 

The State consists of two main drainage slopes: (1) That drained 
southward into the Gulf of Maine by the Saco, Presumpscot, Androscoggin, 
Kennebec, Penobscot, Narraguagus, Machias, and St. Croix rivers, and 
by numerous smaller streams. The average fall of the streams of this 
slope is not far from 7 feet per mile. All the larger deposits of glacial 
gravel appear to be confined to this slope. (2) That drained northward 
and eastward into the St. John River. This slope contains much swampy 
and other rather level land, with here and there hills rising above the 
great plain. 

An inspection of the river systems of Maine shows great irregularities 

5 


6 GLACIAL GRAVELS OF MAINE. 


of surface. In the absence of topographical maps these surface features 
can be described only approximately. A fact of great significance in an 
investigation of the drift of Maine is the presence of numerous ranges of 
hills rising 200 to 1,000 feet above the country to the north of them, and— 
a fact still more significant—they usually were more or less transverse to 
the direction of glacial flow. Part of these have the general northeast 
Appalachian direction, others lie nearly east and west. During the time’ 
of maximum thickness of the ice the glacier flowed up and over these 
hills, but during the final melting these ranges stopped the flow of the 
ice in many cases and confined it to the valleys lying north of them. 
The behavior of the glacial rivers with respect to these transverse 
hills is of great assistance in determining the character of the rivers and 
their laws. 

Much information regarding the kames, eskers, and osars of Maine was 
collected during the geological surveys of Maine made by Dr. Jackson and 
Professor Hitchcock. I have also received assistance from hundreds in 
various parts of the State, but it has hardly been practicable to make the 
proper acknowledgments in detail in cases where the information gained 
from others was subsequently superseded by my own field work. 


NATURE OF THE ROCKS OF MAINE. 


A small area of sandstone is found in Perry and adjoiming towns in 
the southeastern part of the State. With this exception the coast region is 
covered by granite, gneiss, mica, and other coarse-grained schists, with 
small areas of syenite, diorite, and other crystalline rocks. In the central 
part of the State, nearly parallel with the coast, is a long belt of slates and 
other fine-grained schists. Still farther north is a parallel belt of fossilif- 
erous rocks—sandstones, conglomerates, and limestones. Numerous knobs 
and ridges of granite rise in the midst of the other rocks. The contrast 
between these various rocks is great, both chemically and mineralogically, 
and this makes it possible to readily compare the areas of different rocks 
one with another with respect to the composition both of the till and of the 
glacial sediments. Most of these rocks are tough and compact in structure 
and contain free quartz; they are therefore hard to abrade. Except ina 
few places the nature of the rock is favorable to the production of a great 
number of stones and bowlders. The great abundance of gravel in the 


CONDITION OF ROCK IN PLACE. Mi 


glacial sediments, as compared with the amounts of sand and clay, is caused 
by the nature of the rocks. 


CONDITION OF ROCK IN PLACE. 


In Maine, as in a large part of eastern North America, the solid rock 
has been so planed and scratched by the great ice-sheet that only here and 
there is there to be found any residue of the preglacially weathered sur- 
face. ‘The state of preservation of the glacial scratches varies greatly. In 
Brownville, Munson, and all the roofing-slate region, the scratches are 
wonderfully well preserved. On broad, level tops of hills, where the 
wet surface precluded any suspicion that the till had been eroded, I have 
repeatedly found areas of bare rock several rods in diameter upon which 
minute scratches, such as might be made by the finest needle point, are 
still sharply defined, and the situation of the rock shows that they must 
have been exposed to the weather ever since the melting of the ice. But, 
though the durable Maine roofing slate has preserved almost unchanged 
the record that was engraved upon it by the drift agencies, it is far other- 
wise with most of the other rocks. On most of the exposed ledges the 
glacial scratches have either disappeared or are gradually vanishing because 
of the weathering of the surface. Over large areas it is already impossible 
to ascertain the direction of the glacial movement except approximately by 
the forms of the “‘roches moutonnées” or, better, by digging away the 
overlying earth, when the scratches on the subjacent rock will usually be 
found perfectly preserved. Already some of the ledges are split and 
weathered to a depth of several inches, and occasionally to a depth of sev- 
eral feet. All this indicates the condition of the rock before the coming of 
the ice-sheet. During the unnumbered ages of Mesozoic and Tertiary 
time all the State was above the sea, and subaerial weathering and erosion 
had done their long work upon the surfaces of upheaval. The hills and 
valleys were in nearly their present forms, but the surface was weathered 
and shattered often to the depth of 50 or even 100 feet. Over most of the 
State the great glacier removed the weathered rock and planed the surface, 
but here and there the planing did not reach the bottom of depressions of 
weathering. 

The weathering of exposed ledges and bowlders has been greatly aided 
by forest fires and by the burning of brush in clearing the land. 


8 GLACIAL GRAVELS OF MAINE. 


WEATHERING. 


This is the gross result of the action of the elements on exposed rocks 
and minerals. It is partly a chemical process, partly physical and mechan- 
ical. The oxygen, watery vapor, carbon dioxide, nitric acid, ammonia, and 
many other substances present in the air, either constantly or accidentally, 
often combine chemically with the rocks or with certain of their constituent 
minerals. Rain and snow water dissolve many minerals, usually beimg 
assisted in this action by oxygen, carbonic acid, and other. gaseous sub- 
stances absorbed from the air, from the soil, or from decaying organic 
matter. Nor does the process stop with the simple solution of solids and 
liquids; great chemical changes often result. The dissolved substances, 
especially the alkaline compounds, become potent agents to effect new 
chemical decompositions. Thus these substances are not a finality but a 
means to an end. 

A familiar example of solution and chemical decay, and a very com- 
mon one in Maine, is the weathering of the feldspars. By degrees the more 
soluble alkaline silicates are dissolved and carried away, leaving an insolu- 
ble residue, composed largely of kaolin, the characteristic ingredient of 
clay. In like manner the pyritiferous slates and schists are readily disin- 
tegrated. In the presence of rain water the pyrite (or marcasite) is oxi- 
dized and hydrated so as to become ferrous sulphate, or copperas. In Maine 
there are many places, known as “copperas ledges,” where the rock contains 
so large a proportion of pyrite that the copperas is produced in consider- 
able quantities, and after rains in hot weather there is a strong odor of 
sulphureted hydrogen. At the Katahdin Iron Works the chemical reac- 
tions are still more complex; the pyritiferous slate is being rapidly decom- 
posed, the resulting ferrous sulphate being changed to ferric hydrate by 
organic matter. 

In addition to the insidious weakening caused by chemical decay, we 
have the subsequent process of fracture, by both physical and mechanical 
forces. The most common physical causes of fracture are unequal expan- 
sion and contraction under heat and cold, and the expansion of freezing 
water. Various forces act mechanically to produce fracture, such as move- 
ments of the earth’s crust, the pressure of overlying rock, and the impact of 
moving bodies. The solid rock may be fractured to a limited extent by the 


WEATHERING. 9 


direct impact of fluids, such as air or water; but most of the fracturing and 
abrasion effected by moving fluids is due, not to the mechanical impact of 
the fluid, but to the solid masses which the fluid hurls or drags against the 
opposing rock. 

In this complex process of leaching, decomposition, and fracturing is 
seen the explanation of the formation of soil, subsoil, and bowlders in 
those places where the rock of the earth’s crust has been long exposed to 
the weather. Most rocks fracture naturally into angular and rather 
prismatic forms. The subsequent action of the weather variously modifies 
their primitive shapes. Pieces broken off from the solid rock by natural 
means have received many names, such as rock débris, cliff débris, frag- 
mental débris, angular gravel, float rock, disintegrated rock, weathered 
rock, moraine stuff, angular blocks, stones and bowlders of decomposition, 
and, when at the foot of a cliff, talus. The words soil, subsoil, sand, and 
clay describe certain states of weathered rock. Piece after piece is broken 
off from the blocks into which the solid rock was originally shattered, until 
the whole is reduced to a fine powder, known as soil; and since the weather- 
ing usually goes on faster at the angles, the prismatic blocks resulting 
from the original fracture are slowly rounded at the angles and become 
rounded bowlders of disintegration. 

Without the process of weathering there would be no soil on the earth 
except where streams and the sea had battered the solid rock to pieces. 
Take away the power of frost and heat to shatter and the weakening 
effects of chemical decay, and the earth as we know it would no longer 
exist. When first upheaved above the sea, the land might be covered by 
sand, gravel, and clay, imperfectly fitted to be a soil. This would soon be 
eroded away by the rains and streams, and then the continents would con- 
sist of piles of bare rock fit perhaps to bear lichens, but with none of the 
soils, subsoils, and drift which now bury most of the solid rock out of 
sight and which are necessary to the existence of the higher plants and 
animals.’ 


1The process of chemical decomposition of the rocks and soils is greatly aided by the changes 
of atmospheric pressure. On a grand scale these changes are due to the passage of areas of high 
and low barometer; locally they are often due to varying pressure of the winds. As the atmospheric 
pressure increases, air is driven down into the cavities of the earth, and when the pressure is 
diminished part of this air is driven out again by expansion from within. In this manner new sup- 
plies of oxygen and carbonic acid are continually being introduced into the rocks and soils. The 
process is also greatly aided by the rains. 


10 GLACIAL GRAVELS OF MAINE. 


TRANSPORTATION AND THE DRIFT AGENCIES. 


A vast amount of matter, held in solution by subterranean waters and 
by surface streams, is constantly being carried off to the sea. A still larger 
quantity is being transported in the solid condition by various other agen- 
cies. The term “drift,” as here employed, denotes solid matter which for 
any natural cause has left its original position in the rocks, especially if it 
has traveled a considerable distance. 


TRANSPORTATION BY LANDSLIP AND SOIL-CAP MOVEMENT. 


Geologists long ago declared that every particle that has become loos- 
ened from its parent rock is on its way to the sea. As the result of weath- 
ering, isolated fragments frequently become detached and fall rapidly and 
far down steep cliffs; thus, for instance, are stones precipitated upon the 
Alpine glaciers. Other fragments are so slowly undermined that they fall 
only a little way at a time, or at so slow a rate that they slide rather than 
roll down the slope. In the canyons of the Rocky Mountains, and on such 
of the slopes of those mountains as are covered with disintegrated rock, 
many large bowlders of stratified limestone and sandstone have slid down 
the mountain sides many, sometimes hundreds, of feet. The gravel in 
which they are partially embedded slowly weathers or is washed away, and 
the bowlders sink with so little disturbance that the lines of stratification 
are now nearly parallel with their original direction, although long ages 
have elapsed since the bowlders began their journey toward the ocean. 
Every talus or soil shows this imperceptible creep of the separate fragments, 
and the term “soil-cap movement” has been applied to the process. The 
simplest case is where fragments move under the action of gravity alone. 
A more complex case arises when they also sustain the weight of other 
solid particles, as often happens in cases of rock avalanche and landslide, 
which in mountainous regions are important drift agencies. Landslides are 
especially common during the rainy season, not only because of the lubri- 
cating and loosening effect of water on a porous stratum, but also because 
of the weight of the absorbed water. As is well known, extensive land- 
slides have occurred in the White Mountains, and they are not uncommon 
in Maine. 

At the great landslide at Goldau, in Switzerland, flashes of light were 
seen to be emitted from the moving earth. This heat and light must have 


TRANSPORTATION BY WIND. il 


been caused by the heating of particles of crushed rock. The friction of 
the loosened mass upon the underlying rock, as well as the mutual friction 
of the moving fragments, must produce more or less polishing and scratch- 
ing of the stones. It is probable that it would be difficult to distinguish 
such stones from those scratched beneath a glacier. 

On hillsides in Maine the slow, imperceptible sliding characteristic of 
the soil-cap movement has often given an imperfect stratification to fine, 
clayey till. The till becomes softened and somewhat plastic when saturated 
by the rains or upheaved and loosened by the frost. When the eround 
settles, the flat fragments tend to a horizontal position, and on hillsides the 
shearing force caused by the slow downward movement causes the lamine 
of clay and plastic materials to become arranged parallel with the slopes. 
In such situations the till often weathers in layers as regular as those of 
clay deposited in water. Part of this quasi stratification is doubtless due to 
the pressure and shear to which the particles of the ground moraine of the 
ice-sheet were subjected as the ice dragged its vast bulk over them. 

In the modes of drift transportation above mentioned gravity acts 
directly as the impelling force. Another class of drift agencies comprises 
those cases where the transportation is effected by moving liquids or gases, 
including plastic solids, such as ice. In such cases gravity acting directly 
on the transported matter often does not aid the movement; instead, the 
weight of the transported body often has to be overcome by the moving 
fluid. 


TRANSPORTATION BY WIND. 


Where the winds are in general moderate, as they are in Maine, and 
where rains or snows fall at frequent intervals, the climate is not well 
adapted to wind transportation. Yet there are in the State large areas of 
sand now drifting, besides multitudes of dunes long since overgrown with 
vegetation. Thus the wind is seen to be an important drift agency. 

Most of the drifting sands were originally assorted and deposited by 
water. The process of drifting generally begins at some small depression 
in the sand, such as the burrow of an animal. By degrees the depression 
enlarges, and the sand taken out of the hole goes to make up a low ridge 
in the direction in which it is blown by the prevailing winds. It is the dry 
wind that transports sand, rather than even higher winds accompanied by 
rain. The sand grains on the windward side of the ridge, bemg exposed 


12 GLACIAL GRAVELS OF MAINE. 


to the full force of the wind, are blown up and over the ridge, soon to be 
followed and covered by other grains. When the wind changes, these sand 
grains may all be blown back again. As the dry winds in Maine are most 
frequently from the west, the net result of this movement back and forth is 
an unsteady march eastward. In places the dunes have traveled from 1 to 
3 miles up and over hills 200 to 300 feet high. Often a layer of sand is 
left on the ground passed over by the main dune, and then the vegetation 
characteristic of a sandy soil appears. Thus, in western Maine a growth 
of white pines on high hillsides is almost always found on a dune of blown 
sand or on ground passed over by one. 

It is fortunate that blown sands so often leave a trail behind them, for 
the foremost or principal dune thus becomes gradually smaller and its 
power to do mischief is lost unless other dunes follow and overtake it, 
which may happen if the sand 
is very abundant at the place 
where it began to blow. A 
large proportion of the dunes 
now overgrown with vegeta- 
tion have traveled away from 
the sand plains where they 
originated into regions once 


covered by till, clay, or gravel. 


Fic. 1.—Stratification of wind-blown sand; Lockes Mills. 


In most cases it is possible 
to distinguish blown sand from that deposited in its present situation 
by water, even when both are covered by vegetation. The blown sand 
will be found at very irregular elevations and on western slopes, except 
where it has been blown up the western slope of a hill and over its top and 
has come to rest on the eastern slope. Blown sand contains no very large 
pebbles, and is not overlain by bowlders. The dunes form rounded ridges, 
domes, or terraces, and their forms are such as to be recognized at once by 
the practiced eye. Usually the country to the west of a dune is covered 
with more or less sand, a sign that the dune has passed over it. These 
features are sufticiently different from those shown by water-deposited sand 
in similar situations to enable us usually to distinguish them. Fine sand is 
the only material subject to wind transportation on a large scale, yet each 


TRANSPORTATION BY RUNNING WATER. 13 


year there is consideravle blowing of the clay and the finer grains of the 
till or gravel, especially on dry hillsides. It is this blown soil which so 
often covers the snow in winter. It is well known that in exposed situa- 
tions fall plowing results in a considerable loss of soil. Often in hillside 
pastures little cliffs of wind erosion can be seen, worn away partly by the 
direct impact of the wind and partly by the sand and small gravelstones 
blown against their sides. In this way considerable areas have been 
denuded of their surface layers. To this process I have elsewhere given 
the designation “till-burrowing.” It is by far most active along the borders 
of drifting sand dunes, partly because the protecting vegetation has been 
killed by the sand, and partly because in such situations the surface is 
drier than usual. Thus cn a hilltop about 14 miles northwest of Wayne 
Village, cliffs in the till were 3 feet high and the till was eroded to the 
solid rock. The finer parts were driven away and the rock was strewn 
with the larger stones of the till. The gravel thus left is to be distinguished 
from the other forms of gravel. 

The process of till-burrowing is often aided by sheep, which have a 
habit of digging into hillsides in order to lie in the shade of the small cliffs 
thus formed. 


TRANSPORTATION BY RUNNING WATER. 


This is the most common and familiar of all the natural processes of 
drift transportation. The power of running water to transport solid frag- 
ments depends on several elements: (1) According to Hopkins, other things 
being equal, the power to transport increases as the sixth power of the 
velocity. (2) Since in general the force of gravity is to be overcome, it is 
obvious that the specific gravity of the drift matter is to be taken into the 
account. (3) The shape of the fragment to be transported must also have 
an influence on the result, since this determines the relative amount of sur- 
face presented to the force of the current and often the friction to be over- 
come; thus spheres are more easily transported than slabs having the same 
weight. (4) The volume of the current must also be considered. Rocks of 
the ordinary kinds have a specific gravity of 2.4 to 3. When submerged 
they lose one-third or more of their weight, and they will be more easily 
transported when there is volume of water sufficient to wholly submerge 


14 GLACIAL GRAVELS OF MAINE. 


them. It has been estimated’ that the transporting power of different rates 
of river flow is as follows: 


Transporting power of different rates of river flow. 


pate per Rate per Power of transportation. 
| Inches. Miles. 
| 3 0.170 Will just begin to work on fine clay. 
6 . 340 Will lift fine sand. 
8 4545 Will lift sand as coarse as linseed. 
12 . 6819 Will sweep along fine gravel. 
24 1. 3638 Will roll along rounded pebbles 1 inch in diameter. 
36 2. 045 Will sweep along slippery angular stones of the size of 
an ege. 


The specific gravity of the gravelstones is not stated, but presumably 
it is that of ordinary rocks. 

The fragments transported by water are of various sizes, and have 
received names accordingly. The following names have been proposed by 
Prof. T. C. Chamberlin: 

For the very finest particles, mud or clay; for fragments up to size of a 
pea, sand; for fragments varying from the size of a pea up to about 1 inch 
in diameter, fine gravel; for fragments from 1 inch to 3 inches in diameter, 
coarse gravel; for rounded stones less than 3 inches in diameter, pebbles ; for 
rounded stones from 3 to 6 inches in diameter, cobbles; for masses from 
6 inches to 15 inches in diameter, bowlderets; for masses over 15 inches in 
diameter, bovwdlders. 

In this report stones from the size of a pea up to 1 inch in diameter 
are called gravelstones, and the transitions between mud and sand are 
termed silt. 

That rivers are carrying drift matter to the sea is a matter of common 
observation. The sound of grayvelstones and pebbles rattling against one 
another and rolling along the bottom of the upper courses of streams can 
often be heard by one who puts his ear near the bottom of a boat or into 
the water. Everyone has seen streams tear down portions of their banks 
and carry them away. The muddy color of many streams, especially in 


1 David Stevenson, Canal and River Engineering; quoted by Geikie, Text-book of Geology, 
p. 380, 1893. 


TRANSPORTATION BY RUNNING WATER. 15 


time of flood, is due to earthy matter suspended in the water. ‘These facts 
are too obvious to need elaboration. 


SEDIMENTATION. 


For the present purpose it is not needful to go into an elaborate dis- 
cussion of that difficult subject, the hydraulics of streams and other moving 
waters. We have seen that an increase in velocity of current causes an 
increase of transporting capacity proportioned to the sixth powers of the 
velocities. A decrease in velocity causes, therefore, a proportionately 
large decrease in carrying power. Now, the velocity of a stream depends, 
assuming the force of gravity as constant, partly on degree of declivity 
and partly on the friction to which it is subjected. The friction includes 
the viscosity of the water, the friction of the water and of the suspended 
particles against the sides and bottom of the bed, and the friction of the 
suspended particles against one another. In the case of currents containing 
a large amount of solids in suspension, the friction resulting from the 
presence of the suspended matter becomes so great, as compared with the 
other sources of friction, that the velocity is determined chiefly by the load 
of sediment the stream has to carry. Any enlargement of the channel of 
an ordinary stream, unless accompanied by a corresponding increase of 
water supply, causes a slowing of the current. Conversely, a narrowing 
of the channel acts like a partial dam; it increases the slope of the surface 
and is accompanied by a more rapid flow. Any slowing of the current 
will cause matter which could just be transported at the former velocity to 
be thrown down. Such matter is called sediment, and the same term is 
often applied to particles of solid matter while they are yet held in suspen- 
sion. Aqueous sediment naturally settles in successive layers, and such 
drift is said to be stratified. When the current is of uniform velocity, the 
particles deposited are of uniform size. Upon this depends the sorting or 
classifying power of water. 

One of the most common applications of these principles is seen when 
a sediment-laden stream flows into a large body of rather still water, like 
the sea or a lake. The currents are checked gradually, and there is a hori- 
zontal assortment of sediment, the coarsest matter bemg deposited near the 
mouth of the stream and the sediment becoming progressively finer as the 


16 GLACIAL GRAVELS OF MAINE. 


current gradually loses its motion. Such delta deposits are exceedingly 
common in Maine. 

Aqueous sediments are termed torrential when deposited by very rapid 
streams, fluviatile when deposited by ordinary rivers, lacustrine or lacustral 
when deposited in lakes, marine when in the sea, and estuarine when in that 
portion of a river subject to the ebb and flow of the tides. While in one 
sense a portion of the sea, the estuary is inclosed like a river, and therefore 
its deposits differ from those of the open sea. The water is more or less 
brackish, and only the remains of animals naturally frequenting such places 
are found in estuarine sediments. 

The sediment deposited by rains and streams on the land is termed 
alluvium, and when in the valleys of ordinary streams it is often named 
valley drift. Observations in all parts of New England show that a very 
large amount of alluvium was deposited in the larger valleys at or near the 
close of the Glacial period. So characteristic is this alluvium that the 
period has sometimes been termed the Valley Drift period. 

The principles enunciated above enable us to estimate approximately 
the velocities of the rivers at the time the valley drift was deposited. The 
size of the fragments contained in the valloy drift is such that the velocity 
necessary to transport them is generally less than 4 or 5 miles per hour, 
but among the hills it may have reached 8 or 10 miles. This refers to the 
velocity near the bottom of the streams. The slope required to produce 
these velocities varies according to the breadth and depth of the stream, ete. 

The viscosity of water is so small that only very swift currents can 
transport large stones and bowlders up and over a steep obstacle. The 
water at the bottom is embayed or dammed by the obstacle, so that the 
rest of the stream flows over and around the embayed water as well as the 
obstacle. Hence, the mutual adhesion of the pebbles of a gravel bank is 
often sufficient to protect the bank from erosion when the velocity of the 
current is far greater than would otherwise suffice to transport the pebbles. 
The pebbles become wedged together like paving stones, so that they can 
not be moved without friction, and they resist erosion by swift currents as 
the gravels of the seabeach resist the surf. 

A practical application of these principles involves the vexed question: 
How can we account for the presence of stones several inches in diameter 
in the midst of fine sand and clay? It has been usual to refer the cobbles 


SEDIMENTATION. 17 


and bowlderets found in the valley drift to ice floes. No doubt ice floes 
often deposited such stones, as well as large bowlders, but I have lately 
made some observations in Colorado which show that large stones, and even 
bowlders, may be deposited by water upon and within sand. I have 
examined the track of several so-called cloudbursts soon after they occurred. 
Near the centers of these violent thunderstorms a fall of 6 or 8 inches of 
rain and hail is not unusual. This great precipitation takes place within a 
few hours, sometimes within a few minutes. The rain water soon coilects 
on the lower slopes, fills the beds of the streams, and then covers their 
flood plains to a depth of several feet, sometimes overwhelming a broad 
prairie. As the waters flow down the hillsides the hail is rolled along im 
front as a sort of moving dam several feet high. Here and there the waters 
break through this dam and shoot with great velocity down the slopes of 
_ the prairie, soon to be stopped again by the hail. In this way the waters 
are soon concentrated and confined within channels varying from 10 feet to 
several hundred feet in breadth, bordered by walls or dams of hail from 1 
to 4 feet high. 

During one of these floods in El Paso County the flow was so rapid as 
to transport slabs of sandstone 4 feet square and 2 feet thick. These 
bowlders were iron-cemented and heavier than ordinary sandstone. The 
velocity of the current must have been 10 miles or more per hour. In 
narrow rayines of erosion (washes or arroyos) the erosion was very great. 
Blocks of clay were undermined and rolled along in the boiling torrent 
until they were nearly round. A stream 200 to 300 feet wide, and about 
20 feet in depth at the deepest place, issued from the mouth of a narrow 
valley at Templetons Gap, near Colorado Springs. It became somewhat 
wider as it entered the broad open plain, yet for one-third of a mile it was 
swift enough to transport the bowlders above mentioned. Previous to the 
flood the plain at this point was composed of sand loosely grassed over. 
The bowlders were dropped upon the sand plain, which was but little 
eroded by the swift currents. Then as the flow slackened, sand was depos- 
ited upon and around the bowlders to the depth of from 1 to 3 feet. The 
geologist of the future will find the bowlders surrounded on all sides by 
stratified sand. Before I saw and studied these cases it wouid have seemed 
to me impossible that water could have deposited fine sand and large 


bowlders in juxtaposition in this way. Two or three miles farther down on 
MON XXXIV 2 


18 GLACIAL GRAVELS OF MAINE. 


the plain, the flood crossed recently plowed fields. The surface was eroded 
somewhat and was left with numerous swells and hollows, up to a foot in 
depth, yet this small erosion was produced by currents swift enough to roll 
along mud lumps a foot in diameter. About 5 miles below where the flood 
issued from the narrow valley, it became concentrated between banks of 
hail and swept away a house situated on an open plain in the city of 
Colorado Springs. 

These and numerous similar observations in Colorado, beth in the 
recent water drift and in that of Tertiary age, show bowlders of consid- 
erable size surrounded by fine sand and gravel and occasionally embedded 
in clay. It thus appears that swift currents can flow over a stratum of fine 
sediment having an even or level surface without eroding it much, due 
largely to the fact that the lower part of the water is nearly stopped by 
friction. The stream can not, so to speak, get at the sediment while it 
remains coherent. But when a stream impinging against a vertical bank 
undermines a portion of it, the alluvium usually loses its coherence the 
moment it is precipitated into the water. The particles now being isolated 
are no longer able to protect one another by mutual cohesion and friction. 

These observations have a bearing not only on the occurrence of large 
stones and bowlders in the valley drift, but also on the bowlder beds found 
in ancient rocks. I consider it certain that large stones and even bowlders 
may be deposited by running water in the midst of sediments as fine as 
sand, and even in clay. What is required is a rapid current moving over 
an even surface and acting for a rather short time. The sudden storms of 
the Rocky Mountains furnish the required rush of water, and it is quite 
possible that the spring floods of the Valley Drift period also afforded the 
necessary conditions. 

Large stones found in the sedimentary marine clays must have been 
dropped from above by ice or other floating body. 


TRANSPORTATION AND EROSION BY SPRINGS AND SUBTERRANEAN STREAMS. 


This important means of erosion and transportation has not hitherto 
received from students of the drift the consideration it deserves. 

The action of subterranean water is not very rapid, but it is persistent. 
The rain seeping down through the earth dissolves some of its ingredients. 
At depths below the reach of frost this process slowly enlarges the spaces 


TRANSPORTATION AND EROSION. 19 


between the particles. Under favorable circumstances the interspaces by 
degrees become so large that minute sand or clay particles are carried 
along by the water, and thus mechanical attrition helps to enlarge still 
more the passages between the grains of earth. In numerous wells in the 
glacial till the water has been reported as being found in “gravel.” I have 
examined several such wells and found that subterranean waters had 
percolated through the till until they had carried off the finer particles, 
leaving the larger stones somewhat rounded by the flow. J infer that when 
the till was first formed the water percolated through all parts of the mass 
at a nearly uniform rate. By degrees the seeping became more rapid along 
certain lines or layers, where there was the largest water supply or the 
most matter readily removable. These layers soon became more porous 
than the rest of the till and formed a system of subterranean streams or 
“veins.” In my early studies of the till I was often puzzled at these 
apparently water-washed beds of gravel in what would otherwise be 
amorphous till. This phenomenon occurs in the granitic and clay-slate 
regions as well as elsewhere. In such regions the surface waters do not 
sink down into the till in large streams, like the sinks of a limestone region, 
and the till is in most cases, perhaps in all, compact enough to thoroughly 
filter the water before it has penetrated many feet. The presence of muddy 
water in a deep well that is protected from surface wash around its mouth 
indicates subterranean erosion rather than access of muddy surface waters. 
Such cases have happened to my knowledge. However, this erosion is 
rarely so rapid as to muddy the water perceptibly. Obviously the longer 
the process continues the more porous the subterranean channels become, 
and the escape of the waters will be more rapid with correspondingly 
rapid erosion. 

When water is flowing through a porous stratum, especially of sand, 
with such velocity as to overcome the mutual adhesion of the grains and to 
carry them along with it, we have what is known as quicksand. In lke 
manner, gravel will flow like a liquid if water flows rapidly through it. 
This is the cause of the very great amount of erosion effected by what are 
known as “boiling springs.” 1 have elsewhere recorded instances of large 
areas—square miles—of porous gravel eroded and removed by boiling 
springs assisted by surface waters. When a stream impinges against a 
gravel bank, the stones by their mutual adhesion protect one another from 


90 GLACIAL GRAVELS OF MAINE. 


the force of the current. But when water passes from beneath upward 
through the gravel, the surface stones and grains are one by one lifted from 
the others and the water bears them away as if they were a part of itself. 
Thus the principal eroding and transporting work of subterranean waters is 
done as they approach the surface as springs. There is an increased 
velocity as the water nears the place of its release, and all loose matter 
approaches the condition of quicksand. Clay and till are so compact that 
they have suffered comparatively little in this way, but the quantity of 
porous sand and gravel thus removed is surprising. 


TRANSPORTATION BY GLACIERS. 


For the purpose of this report it is not needful to discuss questions 
relating to the structure or behavior of glaciers, except so far as pertains to 
the geological work performed by them. We assume that snow which lasts 
from year to year finally becomes consolidated into ice. Above the line of 
perpetual snow the ice and semiconsolidated snow are known as the névé, 
or firn; below that line, as the glacier proper. Under favorable conditions 
the ice slowly flows, at a rate varying according to the temperature, the 
pressure from behind or the tension from before, the friction, the declivity 
of the surface over which it moves, ete. Whether this is a true molecular 
flow or only the apparent flow of a plastic body—of masses larger than 
molecules—it is not necessary now to determine. Under sufficient tension, 
or stretching force, the ice breaks, producing cracks called crevasses, which 
are known as longitudinal or transverse according to their direction with 
respect to the length of the glacier, or marginal when at the sides. When 
fractured surfaces of moist ice are brought together, they at once cohere, 
and surfaces of dry ice brought together under sufficient pressure also 
cohere. Thus, no matter how often the glacier is rent and torn, it has the 
power to heal its own wounds and to flow on, practically as solid as before. 

Glacial movement conforms to the general laws of flow of fluids. The 
flow is from where there is greater pressure to where there is less, and it is 
retarded by friction at the bottom and sides of the glacier. This friction is 
but another name for the force which the glacier exerts in its efforts to push 
along the rock and other substances in contact with it. 

When weathered rocks project above the glacier, more or less cliff 
débris tumbles down upon the ice. This débris is known as moraine stuff, 


TRANSPORTATION BY FLOATING ICE. 21 


and a mass of it is called a moraine. Moraines are lateral, medial, basal, 
or terminal, according to their situation with respect to the glacier. Moraine 
stuff falling into crevasses is carried forward by the ice, and in this trans- 
portation the stones often scratch one another or the solid rock. Moraine 
stuff beneath the ice is known as a moraine profonde, or ground moraine. 
In ordinary valley glaciers, such as those of the Alps, the ground moraine 
forms but a small proportion of the moraine stuff. But where the whole 
country is covered by ice, and no cliffs project above it, the whole of the 
moraine stuff is beneath the ice or distributed through it. Most of 
the melting of the ice takes place at the surface. The melting waters then 
run along on the surface until they reach a deep crevasse, down which they 
pour, and make their escape by tunnels beneath the glacier. In this way 
each glacier is drained by one or more subglacial streams. ‘The waters of 
these streams are usually muddy and heavily loaded with the finer detritus 
resulting from the grinding of moraine fragments against one another and 
against the underlying rock. In its impetuous course the subglacial stream 
erodes its bed, sand-carves the rock, and forms potholes, like other swift 
streams. During the winter, when the supply of water is diminishing, the 
lower portions of the tunnels of the subglacial streams become clogged 
with rounded sand and gravel. When the ice is thick, it is able to push 
this gravel onward and finally deposit it as a part of the terminal moraine, 
but a thin glacier will flow over its subglacial sediments without disturbing 
even the lines of stratification. 

The general nature of the work done by glaciers, as stated in this brief 
outline, has been established by the observations of so many persons that 
it is here assumed without attempt at proof. Some controverted points will 
be discussed hereafter. 


TRANSPORTATION BY FLOATING ICE. 


Icebergs.— [hese are masses broken off from the front of a glacier. They 
carry more or less moraine stuff, which sinks to the bottom of the sea or 
lake when the ice melts. 

Ice floes —These are composed of the ice formed along the shores of the 
sea or of alake They often contain numbers of the stones and bowlders 
of the beach, frozen fast in them. Other things being equal, ice floes are 
thickest where the tide rises and falls. In the spring they first. melt nearest 


22 GLACIAL GRAVELS OF MAINE. 


the readily warmed shore, and thus become detached. They then drift 
hither and thither under the action of winds or tides, and finally drop their 
burden of drift wpon the floor of the sea or lake, or upon the shore where 
they may have been stranded. 

River ice —This differs from the floe of shore ice only in situation. The 
ice of rivers freezes fast to stones and bowlders, either on the shores or in 
shallow channels. When the ice breaks up in the spring, these stones and 
bowlders are often transported long distances. Frequently as the ice goes 
out it forms jams or gorges in its channel. When the dam at last yields to 
the pressure of the water behind it, the ice often pushes along with it large 
quantities of bowlders and other drift. The moving ice dam acts as a sort 
of glacier, the units of ice motion being the blocks of ice, and not indeter- 
minate masses, as in the glacier. Similar dams must frequently form in 
the channels of superficial streams on the ice, as well as in those of the 
subglacial streams. 


SHAPES OF DRIFT FRAGMENTS. 


Crystalline forms, or those due to crystalline cleavage —In Maine, not unfrequently, crys- 
tals of garnet, quartz, and other hard minerals can be found in sand and 
other forms of drift. Easily cleavable minerals, such as feldspar, are 
usually found in their cleavage forms, more or less modified by attrition. 

Fracture forms. —These are the angular, prismatic, or more or less irregular 
forms into which rocks and minerals fracture under the influence of heat 
and cold, joints, ete. The forms vary according to the composition and 
structure of the rocks, each kind of rock having a prevailing form peculiar 
to itself. These forms are so characteristic that one can often know the 
nature of a bowlder from its shape alone. 

Weather-rounded forms —When rocks are of rather uniform composition and 
structure, their fracture forms naturally weather faster at the exposed angles, 
and thus tend toward the spherical form. For instance, the surface of a 
weathered granite bowlder is somewhat rough, being composed of a great 
number of small crystalline, fracture, and cleavage surfaces, but its general 
shape is rounded. The most of the granitic and syenitic bowlders owe their 
rounded shapes, not to the attrition of the glacier, but to weathering. They 
are no rounder than similar bowlders under the tropics in Egypt. A good 
example of the progressive changes from angular blocks of fracture to 


SHAPES OF DRIFT FRAGMENTS. DR 


rounded bowlders of weathering can be seen on the southern brow of 
Russell Mountain, in the town of Blanchard, Maine. 

Weather-carved forms — When the composition or structure of a rock is not 
uniform, the weathering may proceed in some directions more rapidly than 
in others. The longer such a rock is exposed to the weather the more 
irregular its shape becomes. In this way curious depressions have fre- 
quently been formed on granite or other crystalline and nonfossiliferous 
rocks, which have often been supposed to be the tracks of men or the lower 
animals or of infernal beings. On the islands of Monhegan and Menana, 
off the coast of Maine, are certain markings on the rocks which have been 
described by archeologists as inscriptious. ‘The rather shallow depressions 
forming the so-called letters are formed along three systems of joints of the 
rock. Nota “letter” could I find that had not a crack (often minute) in 
the rock at the bottom of the depression. In numerous instances fractures 
of the rock near by have depressions along them, but no cross fractures or 
depressions to form letters. It is evident that weathering would proceed 
most rapidly on each side of such cracks, and thus in time a depression 
would be made along the line of fracture. The geological evidence is thus 
conclusive that the markings may be simply freaks of weathering along the 
fracture lines of the rocks, and that no human agency is needed to account 
for them. Yet if these markings prove to be capable of decipherment, we 
shall have to assume the existence of a race of men acute enough to take 
advantage of natural fractures and to form letters along them. 

In the western part of Oxford County are many bowlders of a black 
eruptive rock which often have very uncouth and unusual shapes. This is 
due to unequal weathering of the stones. When gathered and placed in 
trains along the walks near the houses, they remind one of the purposed 
hideousness of heathen idols. 

Water-rolled forms — Water has but little ability to grind and polish rock by 
its own impact and friction. It derives its great power immediately from 
the solid matter which it is able to move. In rolling drift fragments it 
acts in two ways—by concussion and by attrition. In the first case the 
fragments are hurled against one another or against the solid rock, and 
since the angles are most exposed to the blows and are also most easily 
broken, the stones are reduced to the well-known rounded form of beach 
pebbles. In the second case the fragments are pushed past one another, 


24 GLACIAL GRAVELS OF MAINE. 


grinding themselves and wearing away the underlying rock. Concussion 
and attrition usually accompany each other, and it is sometimes difficult to 
distinguish between them. Concussion alone would leave the surfaces with 
small granular projections. It is the office of attrition to rub these off The 
attrition scratches of water-transported fragments are necessarily short, 
since friction against the sides of the stones causes them to rotate, thus 
giving them a tumbling motion, with consequent concussion. The distance 
traveled by water-rolled pebbles in becoming rounded must depend on 
many circumstances, including the velocity of the current, the abundance 
of the drift, the condition of the bed of the stream (whether a uniform 
declivity or a series of waterfalls and rapids), and the size, specific gravity, 
hardness, brittleness, ete., of the fragments. 

Forms carved by water-borne sand—F'riction is rhythmical, and whenever the 
solid rock or fragments, which for any cause are stationary for a consider- 
able time, are swept by rapid currents bearmg sand and gravel, they are 
carved into conchoidal depressions or furrows separated by rather angular 
ridges usually tranverse to the motion. Sand carving shows what sort of 
work is constantly being done by the finer detritus—if not too fme—trans- 
ported by a stream. Stones which from time to time are moved ito new 
positions owe their shapes to concussion and attrition of large stones as well 
as to sand carving, and do not show the peculiar depressions due to the 
rhythmical movement of the water over a stationary surface. Instances of 
sand carving can be seen at most of the rapids and waterfalls of Maine 
where the rock is hard and resists weathering sufficiently well. Quartz 
veins in granite afford the finest examples of this process, as, for instance, 
those at Rumford Falls. Sometimes the peculiar markings of sand carving 
are very distinct on small stones which have become wedged into a cavity 
of the solid rock. I found some such near the head of Rumford Falls 
which might have remained fixed in position for several years. ‘The upper 
extremity was faceted to a plane surface, except that it showed the con- 
choidal grooves characteristic of sand carving as distinctly as any of the 
rock in situ. The pebbles of sea and lake beaches are perhaps rounded 
more by concussion than by attrition. According to Sorby and Daubrée, 
very fine sand grains remain angular after motion in water. 

Forms carved by wind-blown sand——Sand and fine gravel, when impelled by the 
wind against bowlders and other stationary objects, rapidly wear them 


SHAPES OF DRIFT FRAGMENTS. 25 


away. In this manner the upper surfaces of stones barely projecting above 
the ground are faceted to nearly a plane, but with more or less of the trem- 
ulous grooving due to the rhythmical friction of the wind. The grooves 
are usually a little deeper, as compared with their breadth, when made by 
the wind than when made by moving water. Sand-carved bowlders are 
very common in western Maine near the White Mountains, especially on 
hillsides facmg the north and west. Thus certain bowlders of peculiar 
shape were discovered by Dr. N. T. True at Bethel Village, and were 
described in 1861 by Prof. C. H. Hitchcock, in a general report upon the 
geology of Maine.’ As I have elsewhere stated,” these bowlders owe their 
unusual shapes to sand carving under the action of the wind. Occasionally 
I have noted sand-carved bowlders in eastern Maine, and many ledges near 
the seashore are carved with sand by both the wind and the surf. The 
process must be common elsewhere, but it can be recognized only where it 
is more rapid than the process of weathering. The striae made by wind- 
blown sand and gravel are usually invisible, and when best developed are 
very short, owing to the ready rotation of the flying grains and stones 
when they strike obliquely against a stone or bowlder. 

Forms scratched, planed, and polished by ice and rocks.—(1) By olaciers. Stones sub- 
jected to attrition by glacier action are said to be glaciated. Many of the 
glaciated stones show distinct scratches, furrows, or striz. But where, as is 
often the case in the till, the stones were rubbed by the finer detritus 
beneath or within the ice, the surfaces received a very fine polish and show 
no distinct scratches to the unassisted eye. Glaciated stones are often 
faceted and are almost always unequally glaciated, some place still retain- 
ing its original surface or fracture. (2) By icebergs. When icebergs grind 
off a coast, the underlying rock must be corraded and scratched by any 
stones that happen to be in the lowest part of the ice and by any sand or 
other detritus or rock fragments resting on the floor of the sea. The frag- 
ments would also be scratched and ground. (8) By shore ice, ice floes, and 
river ice. As shore ice rises and falls with the tide or is urged toward the 
land by winds and the pressure of ice floes, there must be considerable 
attrition of the beach pebbles. Floating river ice must also produce a sim- 
ilar effect, especially when ice gorges have been formed. (4) By landslips. 


1Sixth Annual Report of the Secretary of the Maine Board of Agriculture, pp. 266-267, Augusta, 1861. 
2 Am. Jour. Sci., 3d series, vol. 31, pp. 133-138, Feb., 1886. 


26 GLACIAL GRAVELS OF MAINE. 


The immense amount of earth involved in the Willey Slide in the 
Crawford Notch, and in several other large slides in the White Mountains, 
which were from one-half mile to near 3 miles long, makes it certain that 
there must have been a vast amount of friction of the moving fragments 
against one another and against the underlying rock. The motion of the 
landslip is very much more rapid than that of any glacier, and this would be 
favorable to the scratching and faceting of stones. No one appears to have 
reported finding such stones under circumstances showing conclusively 
that they were formed during the slip. 


Olel A Ie we ICI 


PRELIMINARY DESCRIPTION OF THE SUPERFICIAL 
DEPOSITS OF MAINE. 


A brief general description of the drift of Maine will be given in 
language which for the greater part is consistent with any theory as to the 
origin of the drift. 

Erosion is the general name given to the process whereby a portion 
of the parent rock is removed from its place by any geological agency. It 
is a complex process, consisting of the preparatory work of detaching 
fragments from their original position by solution, chemical decay, weath- 
ering, water-logging of porous beds, abrasion, concussion, and all other 
forms of fracture, and of their subsequent removal by some drift agency. 
The word is sometimes used for the preparatory work only, exclusive of 
the subsequent removal. 


PREGLACIAL DEPOSITS. 


So far as yet determined, all the rocks of Maine are Paleozoic or still 
more ancient. The fact that no marine beds of Mesozoic or Tertiary age 
are found proves that the area within the State has been above the sea 
since Paleozoic time—unless, indeed, deposits of later age have been eroded 
or remain to be discovered. At Brandon, Vermont, are sediments deposited 
ina Tertiary lake of fresh water. Although they were not so firmly cemented 
and consolidated as the ancient rocks, the great glacier was not able wholly 
to erode them. Similar beds might have been laid down in Maine, and, if 
extensive, might have escaped erosion by the ice-sheet. I have, therefore, 
carefully examined the till, especially in the vicinity of the deeper lake 
basins, but thus far have found no fragments of such Tertiary beds. It 
has long been known that marine beds of Tertiary age are found on the 


coast of southeastern Massachusetts, and fragments have been dredged off 
27 


28 GLACIAL GRAVELS OF MAINE. 


the coast a short distance north of Boston. Such beds must have been 
formed on the coast of Maine as it existed at that period. Where are they? 
That they are now beneath the sea is indicated by the contour of the 
coast. Prof. J. D. Dana has rightly urged that the narrow bays of the coast 
of Maine correspond to the fiords of Scandinavia and prove that the land 
formerly stood at a higher level than at present. These bays were once 
valleys of subaerial erosion, now in part submerged. The obvious conclu- 
sion is that the only Tertiary beds likely to be found are those which may 
have been deposited in fresh-water lakes. So far as our present knowledge 
extends, it must be admitted that no lake or river drift of the geological 
ages immediately preceding the coming of the ice-sheet has escaped the 
terrible ordeal of ice. Peats, soils, vegetable mold, and the bones of land 
animals must have abounded, but they were either removed entirely beyond 


the State or were crushed to powder and so incorporated with the rest of | 


the till that no one has been able to recognize them. But negative evidence 
must not be accepted as conclusive. That such sediments have not been 
found by no means proves they do not exist and may not yet be discovered. 

But while sedimentary rocks of the ages immediately preceding the 
coming of the Ice age have not been found, I have noted many instances 
of rock weathered in preglacial time. One of the most instructive of these 
is at one of the slate quarries of Brownville. Most of the rock was plaued 
by the ice to a very level surface. In the midst of the glaciated surface 
was a depression showing a U-shaped cross section. This was probably a 
valley transverse to the section, but its true shape could not be determined. 
The depression was about 6 feet wide and 4 feet deep. ‘The upper and 
central parts of the depression were filled with the clayey, bluish-gray till 
characteristic of the slate region, while in the bottom next the rock was a 
rather pale, brownish-red earth, mixed with fractured and weathered slate. 
Some of the nearly vertical cleavage laminz of the slate had weathered 
away or fallen to pieces, leaving the more enduring laminz projecting into 
the reddish earth from 1 to 4 or even 6 inches, thus forming a very rough 
and serrate surface. This depression was cut across by the quarry excava- 
tion, and at the depth of a few feet below the depression the slate appeared 
as solid as the rest of the quarry. Hence there was no reason to suspect 
the slate of being unusually soft and easily weathered or decomposed by 
waters beneath the till. Besides, the till was compact and unstained by 


GLACIAL DEPOSITS. 29 


percolating waters. As elsewhere stated, this roofing slate resists weather- 
ing to a remarkable degree. All the circumstances make it certain that so 
great an amount of weathering as is shown by the slate in the bottom of 
this depression could have been accomplished only in the long eons of pre- 
glacial time. The bronwish mass in the bottom of the depression is a 
residual earth, a soil of preglacial weathermg. This subject will be referred 
to hereafter. 


GLACIAL DEPOSITS. 


THE TILL. 


Resting upon the glaciated rock (or here and there upon the small 
areas of nonglaciated rock weathered in preglacial time) is the till. It is 
an endless study. So varied are its forms and developments that no 
attempt can be made within the space allotted to this portion of our subject 
to do more than refer to those properties especially related to the subject 
of the glacial gravels. At the present time we do not need to theorize 
concerning the existence of a great body of land ice over northeastern 
North America. Assuming that the area of Maine was covered by a series 
of ice fields that were practically confluent, so as to form an ice-sheet, we 
interpret the facts as to the till in accordance with the glacial hypothesis. 

The names given to the till in Maine deserve notice. A very common 
name for the formation is ‘‘hardpan.” This no doubt refers to the compact- 
ness of the formation and the difficulty of digging into it. Another common 
name is “pin gravel,” though the same name has also been appied to any 
recent conglomerate or water-washed gravel cemented into a firm rock by 
carbonate of lime or by iron oxides or hydrates. The till usually contains 
many stones and bowlders of all sizes, and a soil composed of weathered 
till is commonly known as “hard, rocky land,” or as ‘‘roecky, upland soil.” 
It is often called ‘‘hard-wood soil,” also ‘‘orchard land.” It is unfortunate 
that the term “gravel” is so often associated with the till. In Maine when 
soil is described as “gravelly,” in most cases it is meant that the soil is 
composed of till. ‘‘Gravelly loam” almost always means till, but some- 
times it means a thin stratum of marine clay overlying and partially mixed 
with true water-assorted and rounded gravel. Many know the formation 
as the “bowlder clay.” To apply the terms “gravel” or “clay” to the till is 
a fruitful source of confusion, causing the till to be confounded with water- 


30 GLACIAL GRAVELS OF MAINE. 


washed gravel on the one side and with sedimentary clay containing bowl- 
ders on the other. The term ‘‘bowlder clay” may still have its uses, to 
describe certain disputed formations, but in New England it ought to be 
replaced by the word “till” This word is short, convenient, and implies 
no theory either as to the composition or the origin of the deposit. The 
till constitutes what was known to the older geologists as the “drift” or 
“unmodified drift.” 

In Maine the most constant characteristic of the till is that it 1s com- 
posed of drift fragments of all sizes, from the finest particles of clay and 
rock flour up to the largest bowlders, all indiscriminately mixed together in 
a pellmell mass, except that the lower layers contain more fine matter than 
the upper and a much larger proportion of distinctly scratched or glaciated 
stones. In the area of sedimentary rocks in the northeastern part of 
Aroostook County the till consists almost wholly of sand and clay, most 
of the larger stones having been broken into their constituent grains or 
ground into powder, so as to resemble a soil of preglacial weathering, and 
over large areas bowlders are almost unknown. Although almost all of 
the till has drifted toward the south and east, the distance traveled varies 
greatly. On Matinicus Island I found fossiliferous bowlders of Oriskany 
sandstone which must have traveled 140 or more miles. By count of the 
stones large enough to be plainly recognized lithologically, I have found 
that by far the greater number, especially of those in the lower part of 
the till, were derived from rocks not many miles away. Repeatedly the 
lower till has been seen to be derived chiefly from local rock, while the 
upper layers were derived from a rock that outcropped not far north. On 
the other hand, I have sometimes found near the bottom of the till much 
matter from a distance. Apparently the relative proportions of near- and 
far-traveled matter in the till vary, but I have been unable to discover the 
laws and causes. Sometimes I have suspected that the till of two different 
glacial periods is mixed, but have not been able to find the necessary field 
evidence. That the character of the till changes rapidly as we pass from 
slaty into schistose or granitic areas is proved not only by count of frag- 
ments but also by the general appearance and the physical properties of 
the soil, and often by the vegetation. The greater part of the till of Maine, 
and especially the large bowlders, must on the average have drifted but a 
few miles. 


GLACIAL DEPOSITS. Bl 


DISTRIBUTION OF THE TILL. 


The depth of the till varies greatly. Numerous small areas are bare of 
it. More often these bare places are in the valleys or on the tops of hills, 
especially in the slaty regions. No account is here taken of the areas of bare 
ledges near the sea, denuded by the waves, or of steep hillsides, denuded by 
landslides. In many places bowlders are arranged in trains, presenting the 
appearance of the moraines of modern valley glaciers. I have elsewhere 
described several terminal moraines, most of which appear to have been 
formed in the sea at the extremity of the ice at a time when the ocean stood 
at a higher level than now. So also there are masses of till of various shapes, 
mostly short ridges and irregular heaps, found in low depressions of the 
higher east-and-west ranges, or bordering these passes. They are more 
numerous on the north than on the south slopes of the passes. Such passes 
and low cols would for a time during the decay of the ice-sheet afford exit 
southward for tongues of ice after the glacier had become too thin to permit 
flow over the higher hills. These heaps have not so steep slopes as the ordi- 
nary terminal and lateral moraines of mountain glaciers have, and the shapes 
of the morainal masses deposited by glaciers bearing matter which fell on 
them from above are evidently different from those into which the moraine 
stuff was incorporated from beneath, if we except the extreme terminal 
moraine. It is an interesting study to determine whether thick masses of 
englacial till can be accumulated within the ice by ice movements. The 
term moraine was first definitely applied to masses that accumulated on the 
surface or at the extremity of the ice. It has also been applied to the mat- 
ter beneath the ice. Can it properly be applied to a mass of the ground 
moraine of unusual thickness or to similar masses of englacial till? In this 
report I have not applied the term moraine to masses of till unless they 
present the external and internal characters of the moraines found on the 
surface or at the extremities of ordinary living glaciers; except that ground 
moraine is used as a generic term to indicate the whole of the subglacial till, 
but not individual masses or accumulations of it. 

In the hilly parts of the State the phenomena of “crag and tail” are 
well exhibited. This term refers to the accumulation of till which collected 
in the lee south of projecting hills, especially conical peaks. These accu- 
mulations consist of ridges or deep sheets of stony till, generally of loose 
structure and rather easily eroded by springs and rains. 


32 GLACIAL GRAVELS OF MAINE. 


On the northern and northwestern slopes of rather high hills deep 
sheets of fine, clayey till abound. The till is in general thinner on the 
hilltops and in the valleys than on the intermediate slopes. This fact, 
combined with the rounded, flowing outlines of the mass, gives to these 
hillside accumulations of till a shape somewhat lenticular in cross section, 
but they often extend for miles along the sides of a ridge. 

In the southwestern part of the State, hills of mammillary or lenticular 
shape abound, but they are not so large or numerous as the lenticular hills 


Fic. 2.—Section across deep lenticular sheet of till; Kents Hill, Readfield. 


of till so abundant in certain parts of New Hampshire and Massachusetts. 
Sometimes, as at the eastern end of Portland, there is a rock nucleus, above 
and around which the till collected; but more often no such nucleus appears 
anywhere on the surface, and if it exists it must be of small size as com- 
pared with the whole hill. 

Professor Hitchcock and Mr. Warren Upham named them ‘lenticular 
hills” in the reports of the New Hampshire survey. Similar masses 
appear to have previously received the name of ‘drumlins” in Great 
Britain and Ireland, and this 
name is now generally adopted. 
In Maine the drumlins of the 
southwestern coast region are 
mostly roundish or slightly elon- 


FiG. 3.—Section across Munjoy Hill, Portland. Rock overlain by 


lenticular mass of till, and that by glacial gravel. gated. Back farther from the 
coast, and especially in the eastern part of the State, there are many which 
take the form of ridges, sometimes a mile or more long, with arched cross 


section, like the osars. They contain no water-washed material like the 
osars, and are substantially parallel with the glacial scratches of the region. 
Often I have traveled a long distance in the wilderness in search of a 
“horseback” which had been described to me, and which I anticipated find- 
ing to be an osar, only to find it a mass of till. Such a ridge has been cut 
by the Penobscot River at the mouth of South Twin Lake. The local 


UPPER AND LOWER TILL. 33 


rock is slate. The till next the rock is intensely tough and clayey, being 
mostly derived from the clay slate. The ridge proper rests on this sheet 
and contains a large proportion of granitic matter derived from the granite 
outcrop near Mount Katahdin. The ridge has a sort of lamination, as if 
accumulated in successive layers parallel with its arched surface; yet it is 
true till and at the exposures examined contains no sedimentary matter. 
Near East Vassalboro and elsewhere are a few symmetrical cones which on 
the surface are composed of sandy till. They are found suspiciously near 
the discontinuous kame systems, and this suggests genetic relationship with 
the conical and lenticular kames. As suggested elsewhere, a glacial stream 
that plunges down a crevasse will enlarge its shaft at the bottom and form 
a conical cavity, in which a conical kame will collect if the stream brings 
down coarse sediment. If the stream should for some reason cease to flow 
at this place, it is possible that till might subsequently collect in the ice 
cavity around the original kame as a nucleus; and if little or no gravel col- 
lected in the cave, still it might in some way become filled with till after the 
flow of the stream ceased. 

Irregular heaps and ridges of till, which appear to be mostly composed 
of englacial matter, abound in all parts of the State. When these are 
mapped and masses of the ground moraine distinguished from the englacial 
till, it will be possible to write out almost the whole history of the ice 
movements. The till is more unequally distributed in the granitic and 
coarsely schistose regions than in the areas of slates and sedimentary 
rocks, and its distribution is more irregular near the coast than in the 
interior. 


THE UPPER AND LOWER TILL. 


The upper layers of the till are less compact than the lower, perhaps 
owing in part to the heaving of the frost. No doubt frost has in some 
cases brought up bowlders toward the surface, and this partly accounts for 
the fact that most of the larger bowlders are found on or near the surface, 
but only partly, for in the granitic regions bowlders are often piled one 
above another in such a manner that the frost can not have changed their 
relative positions, and here the larger bowlders are more often at the top. 

The most probable interpretation of the facts is that the finer and more 
intensely glaciated lower portion of the till was deposited in its present 

MON XXXIV——3 


34 GLACIAL GRAVELS OF MAINE. 


position and shapes beneath the ice as a ground moraine proper, while the 
upper part of the till, of less compact structure, less marked glaciation, 
and containing the largest bowlders, is composed of matter which was 
distributed throughout the lower portion of the ice. The classification of 
the till into a lower and an upper member, early adopted by Professor 
Hitchcock in the New Hampshire geological reports (substantially that 
proposed by Torell), seems to have a basis in fact. At one time I thought 
it possible to distinguish in the field between the ground moraine and the 
upper till, but subsequent observations have shown many places where this 
is difficult, if not impossible. Indeed, it appears probable that the two 
formations often blend with each other, so that there is no sharp line of 
demarcation between them. 

It is well known that in the Mississippi Valley there are two or more 
layers of till separated by strata containing peat and other traces of a 
warm interglacial period. No such signs of two general glaciations have 
yet been found in Maine. The few facts that indistinctly pomt that way 
seem as yet to be capable of other interpretations, although during the 
final melting there may have been alternate retreat and advance near the 
ice margin. 


SEDIMENTS TRANSPORTED BY GLACIAL STREAMS. 


These deposits of water-assorted drift have attracted attention all over 
the world wherever they are found. Their most obvious characteristics are 
the following: 

External forms of deposits —The simplest form is that of a cone, dome, or 
hummock, and we find all transitions between these forms and the elon- 
gated, two-sided ridge. When enlarged on all sides, the dome becomes a 
rather round plain with flattish top. The single ridge may fork into two 
ridges, which soon come together again, thus inclosing a basin or kettle- 
hole, which not infrequently contains a lakelet; or it may divide into a 
large number of branches which are themselves connected by transverse 
ridges, the whole forming a plexus of ridges inclosing depressions of all 
shapes. Such networks have been called reticulated ridges by Prof. N. 8. 
Shaler. The depressions inclosed between these ridges are of various 
shapes and have received many names, such as basins, sinks, funnels, kettle- 
holes, punch bowls, hoppers, Roman theaters. 


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NAMES OF GLACIAL DEPOSITS. , 3D, 


Names— These gravel deposits have such curious and distinctive shapes 
that they have received local names wherever they occur. The Scandina- 
vian osars, the Irish eskers (or eskars, or eschars), and the Scotch kames 
are supposed to be the equivalents of the gravel ridges here described, or 
nearly related to them. These deposits contain matter of various sizes, 
from fine clay to large bowlders, but gravel is by far the most abundant. 
I have found the term glacial gravel a convenient general title for describing 
every kind of coarse sedimentary formation which was deposited by glacial 
streams. ‘The term has the disadvantage of implying a theory as to the 
origin of these sediments, and it does not describe their composition in all 
cases, yet it is often convenient as a generic name when there is doubt 
what specific name should be given to a certain deposit, whether kame, 
osar, ete. 

In Maine these deposits have received many local names. The most 
common name is “horseback,” but this name is also applied to a hill or 
ridge of any other kind of material, whether loose material or solid rock. 
They are also known as ‘whalebacks” and “hogbacks.” Sometimes one 
of these ridges is known as the Ridge (as Chesterville Ridge), and they are 
not infrequently known as “ windrows,” ‘“turnpikes,” “back furrows,” 
“ridge furrows,” ‘‘morriners,” and sometimes as “hills.” Several of these 
ridges used to be known as “Indian roads,” because Indian trails were 
made on top of them in the midst of a swampy region. In one place a 
ridge of this kind was called the “Indian railroad.” It may be suspected 
that those who gave it this name had in mind certain archeologists who 
have thought that the osar ridges were built by the Indians. It would cer- 
tainly be remarkable if the Penobscot and Passamaquoddy Indians or their 
predecessors had been so industrious in former ages as to outdo the mound- 
builders and build several thousand miles of these embankments—embank- 
ments far surpassing in size all the mounds of the Mississippi Valley 
and the railroads of Maine combined. Cones of glacial gravel are fre- 
quently known as “ pinnacles,” “hills,” “peaks,” or even as “mountains.” 
Broad, flat-topped ridges have attracted much less attention than the two- 
sided ridges and the cones; yet many of them are locally known as 
‘“plains,” and this is the common name in Maine for a plexus of the reticu- 
lated ridges, or for any broad mass of sand and gravel, especially when 
overgrown by blueberries and other bushes. 


36 GLACIAL GRAVELS OF MAINE. 


Briefly stated, the glacial gravels are found in the form of every kind 
of ridge, terrace, cone, dome, heap, mound, and plain into which loose, 
water-washed matter can be piled, and with both steep and.gentle slopes. 

Topographical relations —Generally these deposits of water-assorted sand and 
gravel are heaped up above the surrounding level. They also take the 
form of flattish-top terraces on hillsides, or they may fill a valley from side 
to side as a plain of level cross section but inclined longitudinally at the 
same slope as the valley. They often form long systems with average 
trend from north to south and nearly parallel with the glaciation. Some- 
times they are found in the valleys of existing streams, but more often 
where no ordinary surface stream larger than a mere brook can ever have 
flowed, even in the time of the most violent floods. Many of the shorter 
systems are only from 100 to 400 feet above the sea at their northern 
extremities, while the longer systems originate at the north at elevations of 
700 to 1,600 feet, a few ridges nearly 2,000 feet high bemg known. The 
northern ends of the distinct systems are higher than the southern ends, 
but the gravels do not follow a uniform slope. The map shows well how 
often they leave the valley of a stream and pass over a divide or low col 
into the valley of another stream. In so doing they not only rise above 
the average grade line of the system, measured from one extremity to the 
other, but they also rise in actual elevation above the sea. Throughout the 
greater part of the State I do not know of any of the systems crossing 
hills more than 200 feet higher than the valleys lying to the north of them, 
But in the southwestern part of the State they repeatedly go up and over 
hills 200 to 250 feet, in one case 400 feet, high (measured on the north). 
Since the height of the hills which the gravel systems could surmount was 
limited, they always penetrate high ranges of hills by low passes. These 
passes are not always the lowest that could have been chosen, nor are they 
always the most direct. Probably in the larger number of cases the gla- 
cial rivers took the best routes for getting from one end to the other, taking 
both grade and directness into account. 

An experienced engineer wishing to construct a railroad between the 
termini of the longer systems as economically as possible, by the shortest 
route consistent with the minimum amount of rise and fall, would in a sur- 
prising number of cases find himself following the same route as the gravel 
systems. A good topographical or relief map of the State would reveal 


SEDIMENTS TRANSPORTED BY GLACIAL STREAMS. » SC 


this fact much more plainly than the existing maps do. Where these gravel 
ridges cross a level and swampy region, they often form a remarkable fea- 
ture of the landscape. In many cases they form natural roadways across 
the swamps and have been utilized for this purpose by both Indians and 
whites. When an explorer has followed one of these great embankments 
for 50 or 100 miles, crossing rivers and valleys, climbing over hills, now 
skirting hillsides far above the valleys, now meandering across a plain where 
nothing now exists to cause meanderings, and bending abruptly in order to 
penetrate some low pass—by the time he has seen all this and noted how, 
within certain limits, these gravel systems disregard the surface features of 
the land, he will be ready to admit the utter impossibility of accounting for 
the existence of water-rolled gravels in such situations by any form of 
fluviatile, marine, or lacustrine agency, or by any known means except by 
streams confined between walls of ice that have now disappeared. 

Sizes and lengths — he narrow two-sided ridges are sometimes barely 3 
feet high and three or four times as broad, and all sizes exist up to 100 or 
more feet high, with corresponding breadth. The broader ridges or plains 
vary in height to a maximum of about 150 feet. The deepest kettlehole 
measured was about 100 feet in depth. Many of the ridges are barely 
wide enough for a road on the top, while massive plain-like ridges are found 
which are from one-eighth mile to more than a mile wide. The plains of 
reticulated ridges are sometimes 3 or 4 miles wide, and the marine delta- 
plams are still broader. Where the gravels, when mapped, are plainly 
seen to be arranged in lines along routes that do not cross very high hills, 
they are assigned to the same system. The gravels of a single system are 
supposed to have been deposited by a single glacial river. The gravel is 
not continuous throughout the course of a system. Sometimes the gaps 
are due to erosion of the gravel, but more often they are due to failure of 
the glacial river to deposit gravel throughout its whole course. The gaps 
are usually less than one-half mile across, but in some cases 2 or 3 miles. 
When gravel deposits are separated by such long gaps, I have never assigned 
them to one system without special proof according to the principles laid 
down here and elsewhere. Several of the systems are 100 or more miles 
in length. 

Branchings—— The branches of the longer gravel systems may be classified 
as follows: (1) Tributary branches. The map shows that many of the 


38 GLACIAL GRAVELS OF MAINE. 


systems receive branches which converge toward the south, like the tribu- 
taries of ordinary rivers flowing in that direction. This sort is especially 
noticeable in the eastern part of the State. (2) Delta branches. Systems 
often divide into two or more branches diverging toward the south, like rivers 
at their deltas. The most remarkable examples of this class of divergent 
branches are found in the southwestern part of the State. When both 
kinds of branches are found in the same system, the tributaries are toward 
the northern end of the system and the delta branches toward the southern. 
Assuming that the glacial gravels were deposited by glacial streams, we 
see that these streams in many respects conform to the habits of ordinary 
surface streams, though their causes and environment were different. 

Meanderings—T he map shows that the longer systems follow tortuous 
courses. Many of these deflections were taken because of the surface 
features of the land, such as the positions of the high hills and low passes. 
There are also many short zigzags which plainly resemble the meandering 
of streams, yet they are found in level regions where there are no surface 
features to cause them. Apparently many of the minor curves and mean- 
derings of the glacial rivers were caused by conditions of the ice which 
did not depend on the land surface beneath the glacier. 

Directions of their courses— The average direction of the gravel systems is a 
little east of south, varying all the way from southwest to south and east, 
and in a few cases for a short distance even a little north of east. While 
there is often a tendency to follow the lines of glaciation, yet there are 
many notable exceptions. Thus, in eastern Maine there is a remarkable 
convergence of several gravel systems toward Jonesboro and Columbia 
Falls. There is a convergence of the glacial scratches toward the same 
points, but it is not so great as that of the gravels. The convergence of 
the gravel systems and that of the scratches are nearly uniform toward 
Belfast Bay. Most of the discontinuous systems are nearly parallel with 
the scratches. At Danforth Village the glacial river abandoned a low pass 
and took a higher one more nearly parallel with the glaciation. On the 
other hand, there is but little convergence of scratches toward Penobscot 
Bay; yet several long glacial rivers which were widely separated at their 
northern ends, united to form a single river a few miles north of the bay. 
The Holden-Bucksport and the South Albion-China systems both take a 
southwest course on account of high ranges of hills. At North Waterford 


COMPOSITION AND STRUCTURE OF GLACIAL DEPOSITS. 39 


a glacial river at one time flowed southwest to Lovell and at another time 
followed the valley of Crooked River for a few miles east and south. So 
also at the south end of Hogback Mountain Pass, in Montville, a glacial 
river took two diverging courses, either simultaneously or at different times. 
Tn both of these cases the larger flow was along the southwestern course 
and over hills of moderate height, while the lesser flow took place down 
valleys of natural drainage and more nearly parallel with the glaciation. 

Composition— These deposits are normally composed of water-assorted 
sediments. The fragments vary in size all the way from the finest clay up 
to sand, gravel, pebbles, cobbles, bowlderets, and bowlders 3 to 4 and even 
5 feet in diameter. Gravel is by far the most abundant material. Clay 
seldom appears except as thin beds in the midst of the coarser sediments. 
Occasionally there are masses in these deposits closely resembling till, yet 
in general the finer matter has so plainly been washed out that there is no 
difficulty in distinguishing them from the unmodified till. They are in fact 
the till more or less water washed, i. e., the residue left after the fine parts 
of the till have been removed by glacial water. 

Internal structure—Most kames and osars are stratified in a very complex 
manner. Both transverse and longitudinal sections of the kame ridge will 
frequently show cross bedding. In the longer ridges the oblique laminze 
generally dip toward the south and obliquely outward toward the sides of 
the ridge, so that in cross section the strata appear to be arched. In the 
broad level-topped plains the stratification is often nearly horizontal. The 
strata are sometimes inclined at very high angles, almost vertical, but only 
locally over small areas, so far as I have observed. In some cases the 
lines of stratification are curved and twisted, probably the result of dis- 
tortion since the original deposition. In a dome or cone the stratification 
is often quaquaversal, and sometimes monoclinal, either parallel or trans- 
verse to the gravel system, as if the deposition took place from the top of 
the cone downward in all directions, or sometimes only at one side of the 
channel of the glacial river. 

In some osars a portion of their length shows no lines of stratification. 
The finer débris has been washed out of them, and the stones even in the 
pellmell portions are plainly rounded by water. It is more probable that 
the present pellmell condition of the sediments is due to the obliteration of 
an original stratification by unequal and irregular settling and sliding 


40 GLACIAL GRAVELS OF MAINE. 


rather than to any freak of sedimentation whereby no stratification was 
produced. If the sediment was deposited upon the ice it would naturally 
lose its structure during the melting of the subjacent ice. 

Shapes of the constituent fragments.—In the glacial gravels we find all degrees of 
water wear. In some of the shorter systems and toward the northern ends 
of many of the longer systems the stones and grains are but barely pol- 
ished at the angles and differ so little from till in their shapes that the mass 
may be regarded as a slightly water-washed till. On the other hand, most 
of the stones and grains of the kames and osars show a very large amount 
of attrition and rolling and are very much rounded. 

Direction and distance of glacial-gravel transportation—In small cones and domes the 
lines of lamination frequently dip outward in all directions, as if the water 
came from above at the center of the cone and flowed downward and out- 
ward on all sides. In the case of ridges, the frequency of transverse and 
oblique dip shows that much of the drift was first at the top and center of 
the ridge, and thence was washed partly lengthwise of the ridge and partly 
sidewise or downward. At the fan-shaped delta localities, where glacial 
streams flowed into broadened channels, or into glacial lakes, or the sea, 
there were many local whirls and eddies where kame matter was transported 
northward for short distances. With the exception of these accidents of 
water motion within the tortuous channels of the glacial rivers or near their 
mouths, the proof is in most cases conclusive that kame and osar transpor- 
tation was southward. In a few places I have found no positive proof of 
the direction of motion. The direction of flow is proved by the following 
considerations: The prevailing southward dip of the laminz of the ridges; 
the higher elevation at the north end of the systems; the direction of the 
flow of the glacier and the position of the termmal moraines; and directly 
and positively by observations on the osar drift itself. Where an osar passes 
from an area of one kind of rock into an area of a different rock, the osar 
drift changes just as the till does, but not so abruptly; itis thus proved that 
the average distance of transportation was greater in the case of the osars 
than in the case of the till, and also that the drift was in the same direction. 
Proofs of this are given elsewhere. Naturally when one sees gravel sys- 
tems going up the northern side of a hill to a height of 200 feet or more, 
it seems incredible that a stream could flow southward over such a barrier, — 
That they actually flowed over such barriers is strong evidence of the 


BEACH AND COVE GRAVELS. {i 


existence of ice. The pressure and head of water necessary to drive streams 
up and over such hills could be secured only in channels or tunnels within 
the ice. 


MARINE DEPOSITS AND GEOLOGICAL WORK OF THE SEA. 


The geological surveys of both Jackson and Hitchcock presented 
abundant proof that clays and sands containing marine fossils are found in 
Maine far above the present level of the sea. Lists of fossils were pub- 
lished, and these were afterwards enlarged by Packard and Shaler. Fossils 
from these beds have been collected by numerous observers, including Mr. 
C. B. Fuller and Dr. William Wood, of Portland; Prof. C. H. Fernald, of 
Orono; Prof. L. A. Lee, of Brunswick, and Prof. R. Stanley, of Lewiston. A 
fine collection of these fossils, made at Gardiner and known (from the donor) 
as the Allen Collection, is now in the cabiets of Bowdoin College. The 
highest level at which fossils have been found, so far as known, is 217 feet 
(Hitcheock’s report). There can be no accurate study of the drift without 
distinguishing between marine and glacial gravels. It therefore becomes 
necessary to describe in some detail the nature of the work which the sea. 
has done over that part of Maine which in the so-called Champlain time 
was submerged in the ocean. 


BEACH AND COVE GRAVELS. 


At hundreds of places along the coast I have examined the slopes of 
the higher hills for traces of old beaches. For the same purpose many 
of the islands were visited, the most important of which lie farthest from 
the coast, viz, Monhegan, Matinicus, and Ragged islands, Isle au Haut, and 
Mount Desert. 

The best place, perhaps, to begin our investigation is at the island of 
Monhegan. This island is located 9 miles off the mainland at Pemaquid 
Point, is surrounded by pretty deep water, and is consequently far from 
shore ice and exposed to the full force of the ocean. The central parts of 
the island form a sort of plateau, from which several small hills rise to a 
height of 120 to 150 feet above the sea. The marginal slopes are rather 
steep on all sides, except at a few narrow coves and on the west side, where 
there is a small sand beach, also the harbor, partially protected by the 
neighboring island of Mananas. The island is about 2 miles long from 
northeast to southwest, and its breadth is about three-fourths of a mile. 


42 GLACIAL GRAVELS OF MAINE. 


Its longer side is thus presented to the open ocean in the direction from 
which the largest storm waves come. Considering the small size of the 
island, its position so far from the land, and the exposure of its flank to the 
storm waves, it is doubtful if any place can be found on the whole coast 
where the sea could act to better advantage. Here we may know what the 
utmost fury of the sea could accomplish, remembering that when the ocean 
stood at higher level than now the island would be still farther from the 
mainland and stiil more exposed to waves from every direction. 

Except near the harbor and at a few small coves, the island is bordered 
by cliffs of erosion at the present level of the sea. On the more exposed 
(east and southeast) sides these cliffs vary in height from a barely percep- 
tible roughening of the rock to 30 feet, and in a few places they are even 
higher. They show the irregular and honeycomb appearance character- 


SEA LEVEL. 


Fic. 4.—Longitudinal section of coye gravel, 


istic of the cliff of wave erosion. In a few places, not far above high tide, 
quartz veins show conchoidal depressions and uneven groovings, due to 
sand carving under the action of the surf. At the head of one of the coves 
are several potholes 10 to 15 feet above high tide. The waves become nar- 
rowed, and consequently higher, as they advance up the cove. They rush 
swiftly up the slope at the ‘end of the cove to a height of 20 or even 30 feet 
above high tide, and then the undertow flows swiftly back. During this 
alternate rush of water in opposite directions the stones and bowlders are 
set whirling in any depressions there may be in the rock, and thus potholes 
are in time eroded. A section across one of these coves or small bays 
shows a mass of beach gravel and bowlders occupying the bottom of the 
valley that slopes down to the cove. In cross section the top of the beach 
matter is nearly level. A longitudinal section shows that it slopes rather 


BEACH AND COVE GRAVELS. 43 


steeply up from the sea to a height determined by the waves, while at the 
same time the undertow has taken a portion of the beach matter out into the 
sea, as shown in fig. 4. 

The distance the finer matter is drawn back into the sea depends on 
many circumstances, such as the height of the tides, the outline of the 
coast, the slope of the shore, the depth of the water, ete. When the slope 
is sufficiently gentle, the forward push of the breakers is greater than the 
backward pull of the undertow, and a ridge of shingle is formed across 
the bays, as shown in fig. 5. Such ridges are named sea walls in Maine, 
and are common on the exposed coasts. The material is derived from the 
erosion of the projecting headlands or is driven up from the sea bottom 
when the slope is very gradual. Indeed, there is always a sort of shelf or 
terrace near low tide, where the force of the undertow is checked by the 
sea, even in the steeper coves. If, now, the slope should become more 
gentle, the forward push of the waves would soon change the terrace into a 


Sealevel, 


Fic. 5.— Transverse section of sea wall. 


ridge rising above the land back of it. Such are the beaches of the glacial 
Lake Agassiz, as described by Mr. Warren Upham, and the old beaches 
of Lake Ontario observed by me in central New York. Occasionally 
such a sea wall was formed in Maine in the period when the sea stood 
above its present level, though the ones examined by me were neither so 
high nor so long as those of the coast to-day. Having the form of an 
artificial embankment across a valley, which they are likely to dam, pro- 
ducing a lake, they have sometimes been supposed to be prehistoric, built 
by the inevitable Indians. 

It is important to note the action of the sea waves upon projecting 
capes. As the waves strike a point of land they are divided, and the water 
is forced obliquely or laterally along the coast toward reentrant parts. 
Loose débris is at the same time driven obliquely away from the projecting 
capes and collects in the bays as beaches or as sea walls. So, also, the 
waves are constantly changing their direction under the action of varying 
winds, and beach matter is transported lateraily along the coast whenever 


44 GLACIAL GRAVELS OF MAINE. 


the waves strike the shore obliquely. As the result of all these causes, 
together with the tidal currents, the projecting parts of the land are denuded 
of loose matter, while the bays and coves are strewn with beach gravels. 

Such are some of the most common modes of wave action as exhibited 
along the present beach. Rising above the beach cliffs, we find that a con- 
siderable part of the island of Monhegan is bare of soil. The local rocks 
weather very unequally. Many of the bare ledges of coarse-grained 
syenitic granite have already been shattered into bowlders and cliff debris. 
Wherever the rock weathers slowly the rounded forms of the roches 
moutonnées are beautifully exhibited. Lverywhere a thin layer on the 
surface has weathered away, and I could find no glacial scratches on rock 
long laid bare. On the north shore was a place where the surf had recently 
undermined and removed the till. Here the scratches were well preserved 
and the rock bore every appearance of having been as violently glaciated 
as it was anywhere on the mainland. It thus appears that the rounded 
bosses of rock which cover a large part of the island are true roches 
moutonnées and owe their shapes to glacial action. As the ice-sheet passed 
over the island, it ought to have left as large a proportion of the surface 
covered with till as it did elsewhere on that coast. But the proportion of 
bare rock is unusually great on this island. If we assume that the whole 
surface was originally covered with till, we find that the greatest amount of 
work that can be assigned to wave action at levels above the present beach 
cliffs consists of (1) the erosion of a considerable part of the till, and (2) 
some attrition, which may have erased the glacial scratches but did not 
obliterate the characteristic forms of the roches moutonnées. When we 
compare the ragged and uneven cliff of erosion at the present beach with 
the still moutonnéed ledges at higher levels, it becomes evident that the sea 
has stood at or near its present position many times as long as at any higher 
level. At the higher elevations the surf had time to erode the till from the 
more exposed shores, but it had not time to form a cliff of erosion in the 
solid rock before a change of level transferred the wave action to higher or 
lower rock. In other words, the changes of level of the sea were relatively 
rapid. 

In a few places undisturbed till was observed resting on the glaciated 
rock, but over most of those parts of the island covered by soil the super- 
ficial deposits consisted of a formation needing careful study in order to 


BEACH AND COVE GRAVELS. 45 


make clear its origin. At first it appeared to be till, but it was soon seen. 
to have lost the finest matter of the till. All material except the finest 

remained in arather obscurely stratified condition. On the northern slopes 

of the island the stones have been changed but very little from their till 

shapes; but on the side next the open ocean the stones are much more 

rounded and polished, though seldom showing such very round shapes as 

those of the stones of the present beach. A section from east to west across 

one of the north-and-south valleys of the island is shown in the accompany- 

ing diagram. 

The slopes are somewhat exaggerated in the diagram. The bare 
ledges on the tops of the hills have become weathered into bowlders of 
decomposition. Some of these are in place; others have tumbled or slid a 
short distance down the slopes, as is proved by their identity in composition 
with the rocks that compose 
the ledges. Are these bowl- 
ders the result of a former 
marine erosion? The lower 
part of the valley is shown 
in fig. 6 to be filled by a 


mass which we now recog- 


nize as beach gravel, com- 


Fia. 6.—Transverse section of ancient cove gravels. 


posed of the till and any 

rock which may have been eroded or washed up by the surf. This is 
overlain by a thin soil composed of peat and vegetable mold, rain wash, 
weathered drift, ete. An examination of the till and the beach gravels at 
high levels showed that both are composed almost wholly of rocks found 
on the mainland to the north of the island. I did not sueceed in find- 
ing a single fragment of the same kind of rock as that on the island. The 
beach gravel is evidently the residue left after the erosion of the far-traveled 
till brought hither from the north by the ice. The finest matter of the till 
was washed out to sea and lost, but the coarser matter remains, and con- 
sists of sand and gravel mixed with larger stones and bowlders, all more 
or less polished and rounded by water. The rarity, perhaps total absence, 
of local rock in this ancient beach is a proof that the sea did not form 
cliffs of beach erosion in the solid rock, though it was able to remove large 
areas of till. It also justifies the inference that, at least in all the cases 


46 GLACIAL GRAVELS OF MAINE. 


examined, the bowlders of local rock found lying upon the beach gravel 
and the soil are due to recent weathering and sliding of the rock, and not 
to wave erosion. 

Fig. 6 is drawn across the valley. Lengthwise of the valley the sur- 
face of the beach gravel has about the same slope as the solid rock of the 
island. In some cases one of these plains of cove gravel can be followed 
all the way up a valley to the top of the island and then downward to the 
sea on the other side. The structure lengthwise of the valleys is shown in 
the diagram, fig. 7. 

If the summit is narrow and rooflike, the gravel is scanty or absent at 
that point; but where the top is a rounded plateau the beach gravel is 
continuous across the whole island. The mode of formation of these con- 
tinuous sheets of gravel, filling the valleys and extending across the whole 
island, is evident. As the sea rose or fell, a valley would always be 


Fic. 7.—Ancient beaches sloping up from shore. 


-oceupied by a bay or cove, and a hill would form a cape. The till would 

be washed away from the hills (then capes) and would be drifted obliquely 
into the present valleys (then bays). If the changes in level went on at a 
uniform and rather rapid rate, a continuous sheet of beach gravel would be 
formed across the bottom of the valley from the top of the slope down to 
the present sea level. If there were pauses in the process of change of 
level, then terraces or cliffs of erosion would interrupt the even slopes of 
the beach. I saw no trace of any such pause, unless at about 25 feet 
above the present beach, where there is an obscure terrace. The valleys 
which have been covered in this way by beach gravels are not, on the 
island of Monhegan, more than one-fourth or one-third of a mile in extreme 
breadth. It is evident that the most violent waves must come from the 
side toward the open ocean, and the fact that this sort of gravel is more 
rounded on the south and southeastern slopes of the island is a jue that 
the stones owe their final shapes to beach action. 


OO EE EEE 


BEACH AND COVE GRAVELS. 47 


That most of the beach gravel laid down by the sea should thus be 
concentrated in the valleys in the form of long and rather narrow sheets, 
directed at nearly right angles to the shore, was rather contrary to my 
expectations, and was worked out only after careful study. There is here, 
on this uneven, rock-bound coast, nothing like the long horizontal terraces 
and ridges of beach gravel observed by Gilbert in the basin of the ancient 
Lake Bonneville in Utah, or by Russell along the old shore of Lake 
Lahontan in Nevada, or by Upham along Lake Agassiz—nothing like the 
“Parallel Roads of Glen Roy” in Scotland or the old beaches of Lake 
Ontario and of the other Great Lakes. 

In several places on this island beach gravels are to be found abun- 


dantly on the north and northwest sides of small conical hills. These 
eravels are in part due to wave action from the northward, but there is no 
reason why waves from that direction should form beaches any deeper in 
such places than elsewhere on the northern slopes. A large part of this 
gravel was washed around and over the hill by the larger waves from the 
open sea toward the south. In other words, this gravel formed in lee of 
the peak which was then a shoal of rock or small island. Instances are also 
found in Monhegan where beach gravel was washed over the top of an east- 
and-west ridge and left in the northern slopes, but this form of beach is 
better shown elsewhere. Here the question is complicated by the fact that 
there was considerable wave action from the north and northwest. 
Matinicus and Ragged islands are situated a few miles off the coast 
near the entrance of Penobscot Bay. ‘They are very near each other and 
show nearly the same rocks. The eastern ends of both islands are nearly 
bare of drift of any kind, and are covered with granite knobs and bosses, 
well moutonnéed. The rocks of the western ends of the islands are schists, 
and show much more drift. The central part of Matinicus Island rises 
about 80 feet above the sea, and is covered with a broad, gently sloping, 
lenticular sheet of blue, compact till, 10 to 30 or more feet in depth. A 
large part of the till-covered area is strewn with several feet of beach 
gravel, little rounded or worn. ‘The till and beach gravel are well exposed 
at the present beach where there are cliffs of erosion in the till. Evidently 
the sea was able to erode only a few feet on the surface of the till while at 
higher level than now, and the slopes of the island were so gentle that the 
eroded till was left as a broad sheet, there bemg no valleys in which it 


48 GLACIAL GRAVELS OF MAINE. 


could be concentrated into beaches at right angles to the shore. The rains 
easily penetrate the beach gravel, until they reach the more impervious 
till; they then seep along the top of the till in the gravel, and escape as 
small springs at the beach cliffs. The till is compact and clayey, and con- 
tains great numbers of scratched stones. It appears to differ in no impor- 
tant respect from the till found in the mainland north of this island. 
Ragged Island is more diversified by hills, and the till has been denuded 
from the southern slopes of the hills and drifted into the valleys, forming 
one or more plains of beach gravel extending across the island from south 
to north, as at Monhegan. 

Isle au Haut is about 7 miles long from northeast to southwest, and 
about 2 miles broad. Its eastern and southern sides are exposed to the 
open ocean. On account of the number of fallen trees and the density of 
the scrub forest, the island is difficult to explore and it is impossible to get 
any general view of the old beaches. Near the southwestern extremity of 
the island I traced a line of beach gravel up a valley to a height of 225 
feet by aneroid. Here the rolled gravel suddenly disappeared, and above 
that elevation only ordinary till could be found. Guided by the barom- 
eter, I then went nearly around the island at this elevation, and at every 
valley found rounded gravel and bowlders up to 225 feet, at which eleva- 
tion the rolled gravel began to thin out, and the contour of 250 feet was 
plainly above the water-washed drift. From that elevation to the top of 
the highest hill (550 feet) not one water-washed stone could I find, though 
they were very abundant and easily found below. On the projecting angles 
of the hills Gvhich would be capes with the sea standing at high levels) 
the till was extensively denuded. No cliffs of erosion were observed above 
the present beach. 

Similar observations were made near Southwest Harbor and at many 
other points on Mount Desert Island, also at many favorable places on the 
mainland. One of the most accessible places for examining the highest 
beach is about 3 miles northwest of Rockland, in the valley of Chicka- 
waukie Stream and Lake. This valley is bordered on the west by a high 
hill or ridge, rismg 400 feet or more above the sea. For several miles 
along the southern and eastern base of this hill rolled gravels are abun- 
dant. In places the gravel takes the form of a distinct terrace on the 


BEACH AND COVE GRAVELS. 49 


hillside, and for 30 to 50 feet above the terrace the rock is nearly bare of till. 
This terrace is very distinct along the west side of Chickawaukie Lake, 
where it has been excavated for road gravel. The stones are distinctly worn 
on the angles, but not so much so as in ordinary glacial gravel. This beach 
extends northward to the village of Rockville and then bends eastward and 
southward along the east side of the valley. When the sea stood at this 
elevation, the Chickawaukie Valley would be a bay nearly one-half mile 
wide, and since there would be few if any islands to the south, it would be 
well exposed to the waves. Three times in as many different years I have 
visited the place in order to measure by aneroid the height of this beach, 
and each time I have been prevented by local storms from making accurate 
measurement. 

Another excellent locality for measuring the height of the highest 
beach is on the southern slope of a rather high range of hills situated about 
3 miles north and northeast of Machias Village. The face of the hill is 
such that, when the sea stood at high level, there would be hardly any 
coves or bays, and it trends nearly east and west. The country to the 
south is low, so that it would all be submerged and this hill would be 
exposed to the unbroken surf. One can take aneroid readings and be down 
to the level of tide water ina few minutes. At 220 feet the top of a terrace 
of rolled gravel and cobbles was observed. The stones were distinctly 
polished and somewhat rounded at the angles. This terrace is from 10 
to 30 feet wide, and is a prominent feature of the hillside. The gravel 
becomes thinner above the terrace, a sort of sheet overlying the till. 
Rolled stones could be found here and there at 240 feet. At 250 feet only 
ordinary till stones could be found, and from this point upward the hillside 
was searched for almost a mile, only till being found. The contrast in 
shape between the stones of the till and those of the beach gravel was so 
great that there was no difficulty whatever in distinguishing them. The 
sea did not here lay the rock bare, or at least did not leave it bare. The 
average of these and many similar measurements, with a good aneroid, 
give the height of the highest beach near the outer coast line as about 225 
feet for the region east of Penobscot Bay, and 230 feet for the region 
between that bay and the Kennebec River. West of the Kennebec I have 
not yet been able to measure the height of the highest beach. A good 

MON XXxIy——4 


50 GLACIAL GRAVELS OF MAINE. 


place for doing so is on Black Strap Mountain, in the western part of North 
Falmouth. It is desirable that the elevation of these old beaches should be 
measured by the spirit level. 

It should be noted that in this report I am describing only what I 
have seen. The sea beach reported by Professor Hitchcock at Fort Kent 
(Geological Report, 1862) I have not had opportunity to examine. In this 
connection it should be added that Mr. R. Chalmers, of the Canadian 
Geological Survey, has determined the height of the highest beach in 
western New Brunswick to be about 220 feet, and it becomes somewhat 
lower toward Nova Scotia. Since the height of the sea rapidly diminishes 
southward in New Hampshire and Massachusetts, it appears that the aver- 
age elevation of the sea on the Atlantic Coast south of Nova Scotia was 
greatest in the region lying between Portland and the Penobscot Bay, or 
perhaps near the mouth of the Narraguagus River. 

To summarize: The rolled gravel of the old beaches is so different 
from the till in composition and shape of the stones, the raised beaches are 
so plainly to be recognized on all the exposed coasts of Maine up to the 
elevations above stated and then so suddenly disappear, that I feel justified 
in referring to the contour of about 230 feet as the highest elevation of the 
sea on the coast of Maine after the melting of the ice-sheet over the coast 
region. As to what may have happened in strictly glacial time, when the 
ice covered the land and extended far out to sea, and when the sea may 
have stood at far higher levels but was perhaps prevented by the deep sheet 
of ice from having access to the land and forming gravel beaches, unless 
possibly here and there at long intervals in the most exposed situations on 
the higher hills and mountains—concerning these possibilities it must be 
admitted that my observations, while not inconsistent with them, do not 
afford the necessary proof. Elsewhere are recorded facts showing that 
probably the sea was at a higher level 50 miles back from the coast than 
on the coast itself, i. e., the relative level of the interior and coast regions 
may not have been the same then as now, there being a greater submer- 
gence toward the northwest. 

The foregoing remarks relate chiefly to beaches Thoin a southern 
exposure. In many places where the waves swept over the tops of hills 
the till was denuded from the top of the hill and left as a beach terrace just 
north of the crest. The waves from the side of the open ocean had so 


BEACH AND COVE GRAVELS. 51 


much more power than those from the coast side that much more beach 
matter was swept northward from hilltops than southward. 

A good instance of this kind of beach is found a few miles south of 
Machias, at the terminal moraine which extends from a branch of English- 
mans River northeastward to near the head of Little Kennebec Bay. On 
the seaward side of the morainal ridge the surface is strewn with bowlders 
and large stones. If they were once water polished, the polished surface 
has weathered away. On the northern slope is a deposit of stratified sand 
and gravel several feet deep, with a few larger stones, as shown in the 
accompanying cross section. The axis of the ridge is composed of till. 
Evidently the waves denuded the upper portion of the till on the southern 
slope and washed the finer matter over the top of the ridge. 

An unusually fine exhibit of the same sort of beach is found on the 
northwestern slope of a northeast-and-southwest hill situated 15 miles east 
of Boothbay Harbor. More or less beach matter is found all along the 
northern crest of the ridge. 
Tn addition there are several 
large bars of beach gravel 
which extend northward, ob- 
liquely down the hill, for 


Fic. 8.—Section across terminal moraine near head of Kennebec Inlet. 


about one-eighth of a mile. 
These ridges are situated directly north of low places in the ridge. Here, 
evidently, the higher parts of the hill were at one time islands, separated by 
narrow straits which occupied what are now the lowest parts of the ridge. 
The waves converged the beach matter and washed it through the narrow 
straits—now represented by the low cols—and a ridge was formed opposite 
each strait. Another fine locality is on the south side of the high hill which 
borders the Chickawaukie Valley on the west, about 14 miles west from 
Rockland. Here a large amount of beach gravel gathered on the north 
side of a conical hill which lay a short distance south of the main hill. The 
place is situated just west of the lime quarries. 

In some of the most exposed situations the beach gravels extend con- 
tinuously from the highest beach down to present sea level, but such places 
form the exception. As we pass inside of the outer islands the power of the 
waves rapidly decreases. Everyone who has sailed along the coast knows 
how much less violent are the waves in lee of even a small island. This 


52 GLACIAL GRAVELS OF MAINE. 


accounts in part for the absence of such long and continuous beach terraces 
as those of lakes Bonneville, Lahontan, and Agassiz. We have seen that 
changes in the level of the sea were rapid, so that the surf beat for only a 
relatively short time at any one level; but we must also remember that the 
land surface of most of the coast region of Maine is very uneven, consisting 
largely of hills and valleys. The hills are in general not high, but high 
enough to form a multitude of islands off the shore as the sea changed its 
level with respect to the land. As the sea rose and fell, not only did the 
shore outline change greatly, but the number and positions of the islands 
changed also. Each island more or less protected a portion of the main- 
land from the fury of the Atlantic waves. Although the waves must have 
beat against all that part of Maine situated below 230 feet, long horizontal 
beaches could not be formed, partly because of the converging of the beach 
outline into the bays, and partly because of the great numbers of protecting 
islands. The places were comparatively few which were so exposed that 
large beaches, measured either horizontally or at right angles to the shore, 
were deposited. The small beaches which must have been formed at that 
time in the landlocked bays and fiords are recognizable now either not at 
all or only with difficulty. Probably the rarity of long, continuous beaches 
is also due in part to shore ice. Hven now, except on the most exposed 
coasts, the shore ice affords considerable protection against the winter 
storms. It is a fair inference that at the time the walrus came as far south 
as Portland the shore ice was more abundant than at present and somewhat 
resembled the Arctic ice foot. 

Résumé.—or several reasons no long and continuous horizontal beaches 
were formed on the coast of Maine by the sea in late glacial and postglacial 
time while it stood above its present level: 

1. The changes of level were too rapid to permit the formation of cliffs 
of erosion in the solid rock. 

2. During the comparatively brief time the surf beat wpon any one 
portion of the land the energy of the waves was chiefly expended in erod- 
ing the till and drifting it away from the capes into the bays. 

3. The positions of the exposed bays and headlands constantly shifted 
during the changes in level of the sea, partly on account of the changes in 
the shore line and partly because of the appearance or disappearance of 
protecting islands off the shore. 


FOSSILS IN THE RAISED BEACHES. 53 


4. The beach was more or less protected by shore ice. 

5. The surf probably beat against the ice during all the time of its 
advance and until the ice had retreated north to the central part of Maine. 

The net result of these causes was that recognizable beaches are found 
only at intervals. Most of that portion of Maine below 230 feet affords 
either no beach gravel or only scant quantities of it. 

It follows from the above that the finding of a sea wall across a valley 
at a certain elevation, or of a beach terrace on a hillside, would not neces- 
sarily indicate a long pause of the sea at that level unless the relief forms 
of the adjacent land show that the sea waves would have as easy access at 
other levels as at that. The fact that those valleys of most uniform slope 
and exposure to the sea do not show well-defined beach terraces proves that 
at least the fall of the sea proceeded at a nearly uniform rate, unless the 
pauses at 225 to 230 feet and at 20 feet be exceptions. 


FOSSILS IN THE RAISED BEACHES. 


On the western slopes of Munjoy Hill, Portland, as pointed out to me 
by Mr. C. B. Fuller, the impressions of various shells and the burrows of 
divers mollusks, ete., are traceable in sedimentary sand and fine gravel at 
elevations of 50 or more feet above the sea. The top of the hill is covered 
with a sheet of glacial gravel, and the fossils are in beds which are stratified 
parallel with the slopes of the hill. The hills of Portland would not be 
in the most exposed situation when the sea beat upon their upper portions, 
yet there would be enough of a surf to erode considerable of the glacial 
sand and gravel from the top of Munjoy Hill. On the whole, I consider it 
more probable that the glacial sand and gravel containing fossils is not in 
the condition it was in when deposited by the glacial streams—that it was 
changed to beach matter by the waves of the sea, which washed it from the 
top of the hill and deposited it on the lower slopes. On the modern gravel 
beaches most, if not all, of the shells are being pulverized so rapidly by 
the beating of the surf that it is doubtful if many of them survive long 
enough to become embedded in the beach matter, unless it be below low tide. 
In several parts of the State I have examined excavations in the high 
beaches at 200 feet and found no shells and no impressions or casts of fos- 
sils large enough to be recognized by the unassisted eye, and no burrows. 


54 GLACIAL GRAVELS OF MAINE. 


At lower levels there are some fossils in the raised sand beaches, but I have 
found none in the coarse gravel and shingle beaches. 


SANDS AND CLAYS. 


Although the areas of denuded rock near the coast suggest that the 
quantity of raised beach gravel must be large, yet it is small when com- 
pared with the broad sheets of sand and clay deposited along the coast 
while the sea stood at higher levels than now. Only a small portion of 
these finer sediments can have been derived from the till and rock which 
were washed away and assorted by the ocean. There was not much wave 
erosion, except on the most exposed coast, and this was situated so far south 
that the eroded till must have been carried out to sea and can not have con- 
tributed much to the marine clays as we find them. The marine clays 
now exposed on the land are composed chiefly of the finer sediments poured 
into the sea by glacial streams or by swollen rivers. Practically they are 
marine deltas. 

The facts as to the fossils of the marine beds are so well known that 
only the briefest reference need be made to them. All writers on the sub- 
ject agree that about the time of the melting of the latest great ice-sheet of 
this region the sea stood considerably above its present level, varying from 
a few feet on Long Island Sound to 500 feet at Montreal. The sediments 
deposited in the sea after the ice retreated from the St. Lawrence basin are 
well represented along Lake Champlain, and were there studied at an early 
date; hence the corresponding deposits of this epoch have been termed 
Champlain by Hitchcock, Dana, and others. A few years ago a nearly 
complete skeleton of a walrus was found in marine beds at Portland, and 
is now preserved in the collections of the Natural History Society of that 
place. Bones of whales, seals, and molluscan life characteristic of an icy 
sea have been found in these beds in great numbers, as was early reported 
by Jackson, Hitchcock, Dawson, and others. In addition to the marie 
fossils, it is claimed that certain teeth, now in the Allen Collection at Bruns- 
wick, were found in the marine clay at Gardiner. These teeth were pro- 
nounced by several authorities to be those of the bison, and on this account 
Professor Packard, in his ‘Glacial Phenomena of Labrador and Maine,”’ 
held that the higher lands were inhabited by the bison at the time the 


‘Memoirs of the Boston Society of Natural History, vol. 1, pp. 210-262, Boston, 1866-1869, 


LOWER CLAYS. 55 


marine clays were being deposited; and if so, there must have been abun- 
dant land vegetation. These teeth have since, however, been submitted by 
Prof. L. A. Lee, of Bowdoin College, to Mr. J. A. Allen, author of ‘The 
American Bisons, living and extinct.”’ This expert, after comparing them 
with a large number of bison teeth, pronounced them to be probably cow’s 
teeth, and of very modern date of deposition. In the present state of the 
argument it will not do to insist on the ancient date of these teeth, and the 
inference of a land vegetation in Maine at the time of the deposition of 
marine clays can hardly be considered sustained. 

The Canadian geologists very generally employ the terms Leda Clay 
and Saxicava Sand for the lower and upper marine beds, respectively. The 
lower clays of Maine contain Leda and other fossils indicative of a muddy 
bottom, and occasionally in a sandy beach I have found Saxicava and other 
fossils characteristic of that sort of sea bottom. We have seen that the 
high beaches are not found continuously, but only here and there in favor- 
able situations. Over almost all the area of the marine beds of Maine the 
lower clay (Leda Clay?) is not overlain by a fossiliferous sand. With 
respect to Maine it is doubtful if the terms Leda Clay and Saxicava Sand 
can be used in a stratigraphic sense as applying to deposits of different age 
laid down one above the other; but the terms may well be used to indicate 
the nature of the sediments which were deposited at different depths and 
under different shore conditions. On such an irregular coast as that of 

Maine the shore conditions would often vary rapidly. My investigations 
do not as yet enable me to give the chronology of the shallow-water sands 
and the offshore clays. As it is not my purpose to refer to the marine 
beds except as they are related to the glacial sediments, it is not necessary 
here to give particular descriptions of the fossils. 


THE LOWER CLAYS: DELTAS DEPOSITED BY GLACIAL STREAMS. 


As already stated, the lower clays are often richly fossiliferous, but 
the fossils are by no means evenly distributed. Thus, both at Brunswick 
and Gardiner the lower clays contain great numbers of shells; while at 
East Bowdoinham, intermediate between those places, the fine blue clay 


‘Memoirs of the Geological Survey of Kentucky, vol. 1, part 2, and memoirs of the Museum of 
Comparative Zoology at Harvard College, both Cambridge, 1876; also Ninth Annual Report of the 
U.S. Geol. and Geog. Surv. Terr., pp. 443-587, Washington, 1877. 


56 GLACIAL GRAVELS OF MAINE. 


which overlies the till contains very few fossils, and over large areas rone 
at all could be found. The lower beds often vary in composition. Gen- 
erally they are a fine blue clay, but in many places they consist of a fine 
sand, which is sometimes quicksand. These alternations of fine sand and 
clay are in a great measure independent of the relief forms of the land, 
and do not represent the horizontal gradations of sediment depending on 
depths of water. They are rather such variations as could be expected in 
a sea into which a great number of sediment-laden streams were pouring 
and where the fineness of the sediments was determined chiefly by the 
positions of the mouths of these streams. In the early part of this epoch 
the streams were smaller than they were later, and were mostly glacial 
streams. The positions of the mouths of the streams were constantly 
changing during the retreat of the ice, and would be affected also by 
changes in the level of the sea. As elsewhere noted, what appears to be a 
kame or osar border clay is sometimes richly fossiliferous. These fossils 
were probably deposited in bays in the ice, into which the salt water 
reached, and while most of the ice was still unmelted. They therefore 
date from an early part of the marine-clay period in Maine. 


THE UPPER GLAYS: DELTAS DEPOSITED BY ORDINARY RIVERS. 


In the upper layers of the marine clays and clay loams I have found 
but few fossils. As noted elsewhere, the same observations have been made 
by Professor Lee at Brunswick and Professor Stanley at Lewiston. The 
probability of finding fossils in the upper clays is greatest near the sea and 
away from the great river valleys. The clays are deepest in the larger 
valleys and near where the great glacial rivers flowed into the sea. The 
fact that fossils are rarest where the clay is deepest proves unfavorable con- 
ditions for marine life near the mouths of both the glacial rivers and the 
ordinary rivers. In other words, the vast influx of ice-cold and muddy 
fresh water during the final melting of the great glacier was destructive of 
marine life. 

The rarity of fossils contained in the upper clays and silts makes it 
very difficult to determine where the marine beds end and those of estuarine 
and fresh water origin begin. For instance, a nearly continuous sheet of 
clay extends from the sea up the valleys of the Kennebec and Sandy rivers 
to a height of 450 feet or more. Below 230 feet this clay is usually dark 


UPPER CLAYS. 57 


blue to brownish blue; above that it is bluish gray; otherwise, to the unas- 
sisted eye, the clay appears nearly the same throughout its whole extent. 
The absence of marine fossils does not prove the exact height of the ocean, 
for this clay is practically nonfossiliferous almost to the coast, 200 feet below 
where the sea has stood, according to the evidence both of fossils and raised 
beaches. This rarely fossiliferous sheet of clay is the basal clay of the 
river valleys above 230 feet and the upper layer of the marine clay below 
that elevation. 

Above the clay which forms the lower stratum of the alluvium of the 
river valleys, we find in the upper portions of these valleys, overlying 
the basal clay, a stratum of coarse sand, or sand mixed with gravel and 
cobbles. This extends across the whole of the valley. As we descend the 
valley we find at a certain point that the coarse matter becomes finer, and 
soon passes by horizontal transitions into sand, which spreads far and wide 
and covers both the fossiliferous and nonfossiliferous clays. In general, the 
slope of the valley above the point of change from coarser to finer sedi- 
ments is now not very different from the slope below that point. This 
rather sudden transition of sediments can easily be explained as due to 
the checking of the current where the rivers flowed into the sea of that 
time. Tried by this test, the sea may have stood at 400 or more feet above 
present sea level in both the Androscoggin and Kennebec valleys. This 
would imply a greater elevation of the sea in the upper parts of these val- 
leys than is shown by the beaches near their mouths. There is as yet no 
fossiliferous evidence of such an elevation of the sea in the upper part of 
these valleys, and, as suggested elsewhere, if we enlarge our ideas of the 
size of the estuaries and lower parts of the rivers at that time, it is possible 
to interpret the facts as exhibited in the field consistently with the elevation 
shown by the fossils and raised beaches—about 230 feet. It is certain that 
in wide valleys or level plains the upper sands begin to spread laterally over 
the marine clays at not far above 230 feet. In the valley of the Andros- 
coggin River these upper sands are well exhibited as delta sands deposited 
by the river in the sea. They extend all the way from a short distance 
above Lewiston to the sea at Harpswell, and send out a branch southward 
through Durham and Pownal to Yarmouth. In the valley of the Kennebec 
the river delta sands end on the south not far from Waterville. 


58 GLACIAL GRAVELS OF MAINE, 


SUMMARY. 


Marine erosion of the till and solid rock contributed but a small por- 
tion of the marme sands and clays of Maine The lower marine beds of 
Maine are clays and very fine sands which are prevailingly fossiliferous. 
The upper clays are rarely fossiliferous, and appear to be contemporaneous, 
or nearly so, with the basal clay of the valley drift. Overlymg the clay 
of the valley drift is a stratum of coarse matter, which changes to sand near 
the old shore line of the sea, and then extends for some distance seaward 
as a fluviatile, not a glacial, delta. The facts indicate that the lower clays 
are chiefly the finer sediments of glacial streams. The supply of sediment 
was at that time moderate, and marine life flourished. Later there was a 
great rush of glacial waters, and about the same time the ordinary streams 
began to flow. These conditions were unfavorable to marine life. Still 
later the sediments poured into the sea were almost wholly those brought 
by the present rivers, then swollen to great size. The sands last to be 
deposited border the river valleys and are plainly deltas formed in the sea 
off the mouths of the rivers. The earlier clays are more widely spread, 
and cover the whole area submerged by the sea, and their thickness bears a 
relation to the systems of glacial gravel rather than to the modern rivers. 

The distribution of the marine beds is approximately shown in the 
accompanying map, Pl. IL. 


VALLEY DRIFT. 


The mass of unconsolidated sediments which is found covering the 
bottoms of most of the New England valleys early attracted the attention 
of geologists. Various names have been given to it, the most common 
being terraces, valley terraces, and valley drift or alluvium. All agree that 
the material was transported to its present position by water, though some- 
times it has been referred to marine rather than fluviatile action. The 
so-called ‘‘intervals” of the Maine streams are almost always plains of 
aqueous sediment, which are usually terraced. Elsewhere are given brief 
descriptions of the alluvium of the larger valleys of the State. A general 
discussion of this deposit is therefore postponed to a subsequent page. At 
present the attention of the reader is called to the more important facts. 

Perhaps the most important fact regarding the sedimentary drift of the 


U. S. GEOLOGICAL SURVEY 


MONOGRAPH XXXIV PL. II 


ae ee | " 


4 4h 
Bes < 


whe 


oP im 
5 Houlton® 
At areal 4 


oe 
Brat 


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PRELIMINARY 
MAP OF MARINE CLAYS OF 


MAINE 


BY 
GEORGE H. STONE 


Pérismouth 


50 STATUTE MILES 


A.Hoen & Co, Lith. Baltimnore 


VALLEY DRIFT. 59 


valleys of Maine is that there is a profound difference between the sedi- 
ments of the valleys above and below about 230 feet above sea level. 
Below that level the country was beneath the sea, and is covered with 
clays and other marine deposits. Unlike ordinary valley alluvium, the 
marine beds do not as a whole show a level plain in the bottoms of the val- 
leys. Over large areas the surfaces of the clay plains undulate somewhat 
like the till beneath them, especially in the broad valleys which were arms 
of the sea, several to 20 miles broad when the sea stood at its highest 
level. As elsewhere noted, the clays are thickest near the mouths of the 
glacial rivers. Hence when we find marine deltas of glacial sediments in 
rather narrow valleys, the offshore clays usually extend over the whole val- 
ley and have a nearly horizontal surface across it. This closely simulates 
fluviatile sediments. The present rivers began to flow at the time the sea 
stood at its highest level. The fluviatile delta sands which these rivers at 
that time poured into the sea are easily recognizable and for a few miles 
extend entirely across their valleys, like fluviatile drift. A little below 230 
feet the sands no longer spread over the whole space then under water, but 
form plains from 1 to 4 miles wide overlying the fossiliferous clays, and 
follow not only the main valley but also sometimes iateral valleys which 
were then straits, such as the line of sands that extends from the Andros- 
cogein at Durham southward to Pownal. 

Above the level of 230 feet we find sheets of sediments covering the 
bottoms of the valleys, usually terraced like the upper Connecticut Valley, 
and in most cases extending from one side of the valley to the other. In 
this portion of Maine (which was not in postglacial time beneath the sea) 
we find the valley drift comparable to that of the rest of northern New 
England. It will therefore be understood that the following remarks apply 
only to that part of the State situated above about 230 feet. 

Over the more level regions the lowest layer of the valley drift is usu- 
ally silt or clay, the upper layers consisting of coarser material, such as 
sand or gravel. As we approach the highlands the sediments become 
coarser in composition. Among the high hills the slopes are often 80 feet 
or more per mile, and the valley drift contains cobbles, bowlderets, and 
sometimes even bowlders. In general, the stones found in the valley sedi- 
ments of Maine are very much less worn and rounded than those in the 
kames and osars. Some exceptions ought to be noted. Thus, near the 


60 GLACIAL GRAVELS OF MAINE. 


northern ends of some of the osars and in some of the smaller hillside 
kames the stones are but little waterworn, and the same is true of the stones 
at the margins of some of the osar-plains and of the smaller solid kame 
plains. On the other hand, the large stones of the coarse valley drift from 
the swift mountain streams are often quite well waterworn, though seldom 
as much so as those of the kames and osars. With the exception of these 
steep valleys among the hills, whenever in Maine we find a plain of appar- 
ent valley drift composed of stones considerably rolled and rounded, we are 
sure to find one of the following conditions: 

1. A short distance up the valley the stream may have eroded a 
ravine or channel through a deep mass of till. In this case the stones are 
those of the eroded till, which were worn and rolled at the rapids formed 
while the stream was cutting through the till barrier. Such a formation 
occurs at Kingman and at many other places. The proof in such cases is 
not complete unless it appears that the deposit of well-rolled stones extends 
only a short distance below the channel of erosion, and that beyond that 
point the character of the valley drift changes. 

2. If we trace both northward and southward such a plain of much 
worn stones, we may find it leaving the vallev and going up and over hills 
to other drainage basins, or it may leave the bottom of the valley and go 
up along a hillside as a sort of terrace. In these cases the apparent plain 
of valley drift is an osar-plain, or broad osar, happening to occupy the 
bottom of a valley. 

3. To the north such a plain of highly rounded stones may end in a 
kame or osar, while to the south the plain becomes finer in composition, 
passing from gravel to sand, and finally to clay. In this case our plain of 
well-rolled stones is a frontal plain of glacial sediments, consisting of matter 
that was brought down by glacial streams to the extremity of the ice (.. e., 
the end of the osar), and there was poured out into the open valley. From 
that point southward the sediment is spread across the bottom of the valley 
like purely fluviatile drift, yet the stones received their shapes almost 
entirely while being transported in the ice channels of the glacier, which at 
the time of deposition lay to the north. Several such frontal or overwash 
plains are described elsewhere. 

In addition to the above-named glacial or semiglacial deposits, we also 
find, in a few valleys haying a northward slope, sediments that were dropped 


RIVER TERRACES. 61 


in local lakes which were confined between the ice on the north and the 
hills to the south during the final melting of the great glacier. 

And now, after eliminating these more distinctly glacial sediments, how 
can we account for the remainder of the valley drift? A great part of it 
is frontal matter, derived from glaciers situated far to the north. Such 
sediment would consist mostly of clay derived from the muddy glacial 
streams, representing work done beneath the ice. In such a case the glacier 
of that time was so remote from where we now find the sediment that it is 
difficult to trace the connection. 


RIVER TERRACES. 


Here and there, at waterfalls and in the swifter parts of their courses, 
the streams of Maine have eroded all the superficial drift, and may even 
flow in channels excavated in the solid rock. A few of these rock channels 
approach the dignity of canyons, as those of the Kennebec above the 
Forks and of the Penobscot below Ripogenus Lake. In general, the 
streams flow in channels lying wholly or chiefly in the till or other super- 
ficial deposit. In addition to the erosion channels in which the streams 
flow when at their average height, we find most of the streams bordered by 
one or more terraces at higher level. The terraces consist of a somewhat 
horizontal portion, or shelf, ending in a rather steep bank or bluff facing 
the stream. The material of most of the terraces is some form of water 
drift, but sometimes it is till, In a few places where the channel proper 
lies in easily eroded sand, there are no terraces above the banks of the 
channel of erosion. This occurs when erosion and deposition are nearly 
equal, and when deposition is the greater. 

River terraces may be divided into two classes. 

1. Terraces of river erosion in drift which was not deposited by the 
rivers themselves. The till and the marine glacial and lacustral sediments 
were deposited under conditions independent of the streams which subse- 
quently began to flow in the valleys of deposition, and the agencies by 
which they were deposited could not have formed a series of terraces to 
which the streams bear a causal relation. River terraces in these forma- 
tions, or in blown sand, must be due to erosion by the rivers. They are as 
plainly formed by erosion on the land as a beach cliff is caused by waves 
and currents. The erosion terraces of Maine correspond to the rock bluffs 


62 GLACIAL GRAVELS OF MAINE. 


_ which border the streams of the Mississippi Valley and the Rocky Mountains, 
except that they have been excavated in unconsolidated drift and within 
a relatively short time. Below the contour of 230 feet all the higher 
terraces which border the rivers of Maine are the result of the erosion 
of till, blown sand, the marine sands and clays, or the glacial sand and 
gravel. Erosion of these formations, especially of the marine clays, has 
been effected on a grand scale. In many places the marine clays have 
been eroded into forms somewhat resembling the ‘“‘bad lands” of the West. 
When a ravine once begins to form, it rapidly extends itself back into the 
clay. Ihave observed several ravines which, within five years, extended 
themselves from one-eighth to one-fourth of a mile and to a depth of 10 or 
more feet. These were formed where there were no permanent streams, 
and were wholly due to the wash of the rains. In the regions covered by 
the marine clays the streams having constant flow are bordered by cliffs of 
erosion, just like the narrow ravines, only the cliffs are situated much 
farther from one another, sometimes from 1 to 3 miles. The ravines and 
cirques of erosion are so characteristic of the clay-covered regious that by 
them one can recognize most of that part of Mame which was under the 
sea, even when deeply covered by snow. The till, bemg much harder to 
erode than the sedimentary drift, rarely shows cliffs of erosion at levels 
above the channel proper, except where the flow of the stream in time of 
flood is very much greater than the ordinary flow. Hence the scenery in 
the areas covered by till is very different from that of the clay regions. 
The methods of terrace erosion will be more fully considered hereafter. 

2. Terraces composed chiefly of valley sediments. The simplest case 
is that of the present flood-plain terraces. They rise to only a moderate 
height above the present beds of the streams, and now and then they are 
overflowed in time of high water. The drift of the flood plain is of very 
composite origin. Part of it is usually the uneroded remains of a sheet of 
drift laid down previous to the flow of the stream at its present level—either 
till or the marine beds or valley drift deposited near the close of the Glacial 
period. Part of it is of recent origin, consisting of sediment deposited by 
the stream in time of flood or of matter brought down by the rains from the 
higher terraces and the hillsides. Wherever deposition equals or exceeds 
erosion, the flood plain is not nominally bordered by steep cliffs or banks of 
erosion, but it simply extends to the sides of the valley, sometimes being 


RIVER TERRACES. 63 


perceptibly higher near the stream. In other words, the valley is fillmg 
with sediment. This is the condition of the stream and valley at the delta, 
provided the flow of water is sufficient to cover the whole valley from side 
to side. In a few places this is the present condition of the valleys, as, for 
instance, the valley of the Crooked River for a few miles north of Sebago 
Lake. Most of the more level portions of the larger valleys of Maine 
must have been in this condition at the close of the Ice age. 

A strict classification would distinguish the flood plain of erosion from 
that of deposition. Practically the two processes are intimately blended. 
On the steeper slopes the flood plain is almost always due to erosion in 
times of flood; on the gentler slopes it is composed wholly or in part of 
matter deposited by the flood waters. It is often difficult to determine 
which of the two processes has been more active. In field use, the term 
‘flood plain” implies the lowest river terrace which is now overflowed by 
the river in time of flood, without regard to the origin of the terrace. 

Below the highest postglacial level of the sea (230 feet), we find the 
larger streams bordered by a rather narrow flood plain, above which rise 
one or more erosion terraces in the marine beds, or in the glacial sands and 
gravels, or sometimes in till. Soon after we rise above 230 feet we find 
one or more river terraces in the so-called valley drift. In addition to the 
marginal terraces, several of the valleys show large ridges lying along 
the axis of the valley. The largest and longest of these that I have 
observed were found in the Kennebec Valley above Solon, in the valley of 
the Little Androscoggin above South Paris, and in the Piscataquis Valley 
above Abbott. The number of marginal terraces varies. In general, the 
top of the central ridge has nearly the same elevation as the higher mar- 
ginal terraces. Both Jackson and Hitchcock report terraces in the upper 
Kennebec Valley at elevations such that they must be higher than the 
central ridges. These highest terraces are so obscure that I hesitate to 
call them terraces. 


RECENT EROSION OF THE VALLEY ALLUVIUM AND OF THE GLACIAL SANDS AND 
GRAVELS. 


Before discussing the origin of the higher river terraces, it is necessary 
to inquire what sort of geological work is now going on in the river valleys. 
We can not declare that the higher terraces above the flood plain are due 


64 GLACIAL GRAVELS OF MAINE. 


to erosion (the common theory) until it is proved that erosion is now going 
on at such a rate as to justify the induction that the terraces could have 
been eroded within the time that has elapsed since the Valley Drift period. 
Thus, for instance, the Kennebec and Sandy rivers are bordered for many 
miles by bluffs or terraces 50 to 80 feet high, and between these blutis lies 
a valley one-fourth to three-fourths of a mile wide. On the erosion theory, 
there is a very large amount of denudation and transportation to be accounted 
for. We have already noted that areas of the marine sands and clays from 
1 to even 5 miles in diameter have been eroded by rains and streams to a 
depth of 10 to 70 feet or more. 

According to a common theory of stream erosion, the terraces were 
eroded directly by the rivers as they wandered back and forth over their 
flood plains, or by their lateral branches. On this theory the base of every 
bluff or terrace was once washed by the river or its tributaries, at least in 
time of flood. This process of erosion by meandering can be seen in oper- 
ation in many valleys, and is no doubt a common, and in greater or less 
degree a universal, process. But there is in operation in Maine a process 
which is often far more efficient in eroding wide valleys than meandering. 

We have seen that the upper stratum of the valley drift is usually 
coarser than the lower. Hence the surface waters soak readily through the 
porous upper stratum until they reach the rather impervious underclay. 
They then seep laterally through the basal layers of the sand and gravel 
and along the top of the clay until they find exit in the form of boiling 
springs. The same thing happens at the plains of glacial sand and gravel, 
only in this case the water is generally arrested by the till. Thus, boiling 
springs often reveal the presence of glacial gravel hidden beneath marine 
clay. The reasoning is as follows: Large boiling springs are rare in the 
till, unless for a short time while the snow is thawing in the springtime. If 
such a spring issues from a suspected ridge, the ridge is more likely to be 
glacial gravel than till. The decisive test is furnished by the stones found 
in the boiling spring and its outlet, which will be well rounded if the spring 
issues from a mass of glacial gravel, and will not be the ordinary tillstones. 

A fine instance of recent erosion by springs can be seen a short dis- 
tance south of Solon Village. The plain of the valley drift which occupies 
the valley of the Kennebee River here extends for one-half mile or more 
east of the river. Back from the river at varying distances up to one- 


ORIGIN OF RIVER TERRACES. 65 


fourth of a mile is a crooked bluff. At one place the bluff makes a very 
reentrant curve and borders a cirque, locally known as the ‘Hopper hole.” 
There can be no doubt as to the origin of this bluff Within a few years 
preceding 1878 (the date of my visit to the place), the subterranean waters 
had eroded a ravine 10 to 70 feet deep and had cut back into the plain for 
300 feet. In spite of the most strenuous efforts to stop the washout in 
order to save the public road, it had been necessary to change the road 
twice. Large piles of brush, logs, bowlders, and various kinds of rubbish 
had been thrown into the ravine. The flow had at times been tempo- 
rarily stopped, but the waters collected as behmd a dam, and the porous 
sand and gravel over considerable areas became permeated by water 
under pressure until a considerable part of the gravel plain was im the 
semiliquid condition of quicksand. Finally either the dam was swept 
out of the ravine or the sand-and-gravel plain was washed away around 
the ends of the dam. When once the sand and gravel was in motion, it 
passed readily into the river, very little being dropped on the way. The 
work of the river consisted in carrying away the sediment furnished it by 
the springs. Here is an unmistakable case of steep cliffs or bluffs of 
erosion formed at a considerable distance from a river, not by the meander- 
ing of the river but by rains and boiling springs, the surface wash being 
small compared with the action of the subterranean waters. 

The great amount of erosion effected by subterranean waters as they 
rapidly flow out of a porous mass of sand and gravel has recently been 
demonstrated at a point 5 or 6 miles northeast from Cherryfield. The site 
of the washout is at a boiling spring which had long been known to issue 
from the southern edge of the great glacial sand and gravel plains of 
Deblois and Columbia. The plain here ends in a steep bluff facing the 
south, and rises 50 feet above the plain of marine clay at its base. At the 
time of the washout a ravine 100 feet long, 25 feet wide at its base, and on 
the average 30 feet deep, had been cut back into the gravel plain, and the 
eroded matter had been spread over an area of 2 or 3 acres at varying 
depths up to 4 feet. No surface stream is to be found on the gravel 
plain near this place, and the cause of the eruption lay beneath the plain. 
During the winter of 1885-86 there was a thaw, during which a large 
amount of snow melted. Soon after there came a remarkable storm. The 
precipitation took the form of snow in the interior of the State, but over a 

MON XXXIV. 


5 


66 GLACIAL GRAVELS OF MAINE. 


belt 20 to 40 miles wide next the coast there was a heavy fall of rain and 
sleet. It is known as the ‘‘ice storm,” because thick ice gathered on the 
trees and broke down thousands of them, besides numberless branches. 
The next July after the washout the matter eroded from the plain could be 
seen overlying great numbers of limbs that had recently been broken off 
and the tops of several small trees recently bent to the ground. The wash- 
out, therefore, must have occurred during or soon after the ice storm. Evi- 
dently the unusual rush of subterranean water was due to the snow melted 
during the thaw, assisted by the rains of the subsequent ice storm. The 
water seeped down through the porous gravel until it was stopped by the 
till or solid rock, and it could then find exit only by flowing out from the 
side of the gravel plain, which it did so rapidly as to effect the large erosion 
above stated. 

We thus have not only the ordinary and unceasing erosion of porous 
sediments by springs boiling up through them, but also from time to time 
these extraordinary outbursts. The most destructive outbursts take place 
in winter and spring. In Maine the ground ordinarily freezes in winter to 
a depth of 2 or 3 feet, and it must often happen that the smaller outlets by 
which the seeping waters escape will be frozen solid. The waters thus 
temporarily dammed will accumulate until considerable pressure is attained 
and will help to increase the velocity of the escaping water when at length 
the ground thaws and a passage is forced. The dams or gorges which often 
form in rivers when the ice breaks up in the spring must have the same 
effect on porous valley alluvium. The pressure of the water above the ice 
dam must sometimes cause a rapid seepage through coarse gravel and cob- 
bles and the formation of erosive boiling springs at points below the dam. 
As noted elsewhere, the erosive power of a stream when flowing out of a 
mass of gravel is much greater than that of the same stream when sweep- 
ing past the base of a body of the gravel. The remarkable amount of 
erosion of osar-plains by even small streams is well illustrated near Knox, 
between Canton and Livermore, and between Rumford and North Wood- 
stock, as described elsewhere. It is noticeable that moderately coarse 
gravel plains are eroded even more than fine sand. 

Universally, so far as my observation goes, the narrow ridges of glacial 
gravel (kames and osars) have resisted erosion better than the large plains. 
This fact seemed unaccountable until I began to investigate the action of 


ORIGIN OF RIVER TERRACES. 67 


subterranean waters. It then became evident that erosion is often more 
active from within than from without. Large boiling springs can form only 
where there is a large surface of porous matter, since the seepage of such 
matter varies with the surface exposed to the rains. It follows that this 
kind of erosion was formerly more rapid than at present, since there was 
then a larger surface exposed. In case of some of the osar-plains the 
amount of subterranean water must once have been two or more times 
the present supply. In this connection it should be noted that the rainfall 
of Maine is from 40 to 56 inches annually. 


ORIGIN OF THE HIGHER RIVER TERRACES OF THE VALLEY DRIFT, 


The following considerations bear on this disputed question : 

1. The facts stated above, and elsewhere, prove that the larger plains 
of sand and gravel are now being rapidly eroded at considerable distances 
from streams by rains and subterranean waters. In many cases it can be 
proved that these agencies are more efficient in eroding high-level terraces 
than is the meandering stream. 

2. Many of the river terraces which are situated above 230 feet extend 
continuously down their valleys until they end in terraces in the marine 
clays. But the latter are plainly due to erosion. 

3. The marine beds have been eroded over areas 1 to 3 and even 5 
miles broad. A less amount of erosion, though of coarser matter, will 
account for all the river terraces above the former sea level. 

4. The upper portion of the valley drift is so generally coarser than 
the lower that the conditions for rapid erosion by subterranean waters are 
afforded by most of the larger valleys of New England. 

5. The formation of terraces and bluffs of erosion not distinguishable 
in form from the ordinary river terrace has been observed in recent time. 

Two theories as to the origin of the higher river terraces of valley 
drift demand examination: One is the erosion theory, according to which 
the steep bluffs are the result of the partial erosion of a sheet of sediment 
which once extended across the valley. The other is the theory suggested 
by Prof. J. D. Dana, to account for the terraces of the upper Connecticut 
Valley.* , 

According to the latter theory, the terraces were deposited at the 


'The flood of the Connecticut Valley glacier, Am. Jour. Sci., 3d series, vol. 23, pp. 87, 179, 360, 1882. 


68 GLACIAL GRAVELS OF MAINE. 


margin of a river which then filled the whole valley to the height of the 
terraces. The water rose by successive stages, and the central parts of the 
valleys were never filled by a sheet of drift, as postulated by the erosion 
theory. The erosion theory postulates a water channel along the valley, 
and a pretty large one, but by no means so large as the whole space 
included between the terraces. Professor Dana’s theory requires several or 
many times the amount of water required by the erosion theory, i. e., the 
stream must have been swift enough to keep its supposed channel (the 
space between the terraces) free of sediment. 

The presence in several of the river valleys of a central ridge, so 
evidently an uneroded portion of a once continuous plain, strongly favors 
the erosion theory as to the formation of the broader terraces of valley 
drift up to the level of the central ridges. This includes most of the ter- 
races. Perhaps I have not seen the terraces at very high level, noted by 
Jackson and Hitcheock in the Kennebec Valley, though I looked for them; 
but I have notes of a few narrow terraces above the erosion terraces which 
seemed to have been deposited in substantially their present shapes. heir 
material resembles that of the glacial gravels, but is not much rounded. 
These terraces were at first judged to be ordinary glacial gravels, but they 
preserve so nearly the same longitudinal slope as the valley drift proper as 
to give good ground for suspicion that they were formed at the margin of 
the valleys, as suggested by Professor Dana. But if so, it is not certain 
that they were formed at the margin of a great river fillmg the whole valley. 
During the final melting, the ice in the valleys 


if we may follow the anal- 
ogies of ordinary glaciers flowimg in valleys—might sometimes melt fastest 
on the side next to the warmed hills. A stream would form in these mar- 
ginal depressions, and the sediments deposited in them would now appear 
as terraces. These narrow high-level terraces may therefore be of semi- 
glacial origin, i. e., formed between the bare hills on the one side and the 
ice of the valley on the other. 


SUMMARY. 


The channels of the rivers of valley drift time have been greatly 
deepened and widened, partly by the direct action of the rivers upon the 
valley drift which then filled up the lower parts of the larger valleys, 
partly by the rains and by subterranean waters. In this process terraces 


ORIGIN OF RIVER TERRACES. 69 


have been formed; and while most of the terraces are due to the carving 
and partial erosion of alluvium previously laid down, yet a residue remains 
where narrow terraces may have been deposited in substantially their 
present shapes, either at the sides of an ordinary river of great size or along 
the margins of a mass of ice filling the central parts of the valley. The 
question will be more fully discussed later (see Chapter V1). 


Olah ay Jest 1d) Je, IE’. 


GENERAL DESCRIPTION OF THE SYSTEMS OF GLACIAL 
GRAVEL. 


According to the nomenclature here adopted, a system comprises the 
sediments deposited by a single glacial river with its tributary and delta 
branches. 


VANCEBORO SYSTEM. 


Two well-defined osars converge at Vanceboro station. One has been 
traced for about 14 miles northwest of the station, as a low ridge, scarcely 
rising above a bog. The gravel is distinctly waterworn, and the ridge 
would naturally extend farther north, but such extension has not yet been 
‘traced. The railroad station is built on the gravel of this ridge. The 
other osar is a two-sided ridge, from 10 to 30 feet high, which follows the 
west shore of the Lower Chiputneticook Lake for somewhat more than a 
mile north of Vanceboro, when it seems to end in a bog near the lake. The 
shore of the lake here bends toward the northwest, and the northern exten- 
sion of this system, if there is any, would naturally be found on the north 
side of the lake in New Brunswick. Numerous persons have reported to 
me that ‘“‘horsebacks” of gravel are found in the valley of Palfrey Brook, 
but I can not be certain from the descriptions whether these-are till or true 
glacial gravel. A horseback on Kel River, in York County, New Bruns- 
wick, has also been reported. Mr. R. Chalmers describes it’ as a large 
ridge, probably beginning in Maine and thence extending southeastwardly 
along the valleys of Bull Creek and Eel River to First Eel Lake, where it 
disappears under the lake. Mr. Chalmers’s description shows this to be an 
osar. So large a ridge implies a glacial river of considerable size. As it 
does not seem to end, according to Mr. Chalmers’s description, in a delta- 


‘Report on the surface geology of western New Brunswick: Geological and Natural History 
Survey and Museum of Canada, Report of Progress for 1882-83-84, p. 25 GG, Montreal, 1885. 
70 


VANCEBORO SYSTEM. 71 


plain at First Eel Lake, the river would naturally have flowed farther south 
or southeast. If so, the Eel River osar may prove to be a continuation of 
one of the osars that unite at Vanceboro. 

A short distance north of the railroad bridge at Vanceboro is a small 
and rather level-topped plain of sand and fine gravel which extends west- 
ward from the main osar ridge. It ends in a steep bank, and is quite regu- 
larly stratified, the strata dipping outward. The material is somewhat 
coarser near the main ridge than at the edges, and therefore the deposit 
presents the external appearance of a small delta ending in sand, showing 
that the currents were not wholly checked. 

Just south of this plain the St. Croix River bends to the westward and 
crosses the line of the osar. There is a short gap in the ridge at this point, 
perhaps due in part to erosion by the river. A ridge begins a few rods 
south of the railroad sta- 
tion (near where the two 


glacial rivers united), and 


thence a well-defined ridge ee 
te) ge 


«et 
hen 


aon ene i> 


or series of ridges is formed 
along the St. Croix tor 
about 5 miles, it being 


Pe = 
IPATHEF]COOK 


most of the way on the 
west side of the river. At 
the mouth of Trout Brook the river makes an abrupt bend westward, 


Fie. 9.—Osar and delta-plain inclosing lakelet, Vanceboro 


and the course of the gravel system is uncertain. Large sand-and-grayel 
plains are reported by Prof. G. F. Mathew,’ near Lynnfield, Charlotte 
County, New Brunswick. I did not personally explore the valley of the 
St. Croix for several miles south of Vanceboro, and my marking of the 
probable course of this glacial river as extending from the mouth of Trout 
Brook southeastward past Mud Lake to Lynnfield, where it would naturally 
deposit delta-plains, is provisional. The Lynnfield plains appear to be con- 
siderably above the contour of 225 feet, and this glacial river may have 
deposited gravels south or southeast of them, perhaps down the valley of 
the Digdequash River. 


‘Report on the superficial geology of southern New Brunswick: Geological Survey of Canada, 
Report of Progress for 1877-78, pp. 13-14 mE, Montreal, 1879. 


72 GLACIAL GRAVELS OF MAINE. 


DYER PLANTATION SYSTEM. 


An osar from 20 to 40 feet high extends from near the mouth of Big 
Simsquish Stream southward nearly parallel with the St. Croix River for 
about 3 miles, in Dyer Plantation, Washington County. It then takes 
the form of somewhat discontinuous low bars and terraces, which perhaps 
are a poorly defined osar-plain. This extends past the enlargement of the 
St. Croix River known as Loon Bay to the mouth of the Canoose Stream, 
where the system crosses into New Brunswick and sends out two tongues 
of sand and gravel for about 6 miles southeastward, one on each side of 
Basswood Ridge. I saw, in 1879, only a portion of these plains. They 
appeared to be rather level on the top, with the exception of a few two- 
sided ridges here and there rising above the rest of the plain. They present 
the external features of a delta-plain, either marine or deposited in a glacial 
lake. 

For several miles above the mouth of Little Simsquish Stream I could 
find no glacial gravel on the west side of the St. Croix, but could see across 
the river on the Canadian side considerable gravel of some kind in the form 
of terraces. For about 1 mile above the mouth of Scotts Brook the gravel 
near the St. Croix was very nearly in shape that of tillstones. This makes 
it highly probable that the Vanceboro system does not continue in the St. 
Croix Valley below the mouth of Trout Brook so as to connect with the 
Dyer system. I could find no trace of this glacial river to the north or 
west of the mouth of Big Simsquish Stream, unless a small plain covered 
by a thin sheet of sand may have been deposited by it. This plaim is over- 
grown with pines, and is situated not far from Scotts Brook, about halfway 
from Lambert Lake to the mouth of that stream. The country is a dense 
wilderness, and one might pass very near a large osar and not see it. 

The osar in Dyer contains many rounded bowlderets and some bowl- 
ders. In many places the lateral slopes are very steep. According to 
Anson,} the elevation of the head of Canoose Rips is 211 feet; that of the 
foot of Rocky Rips, near the north end of the Dyer osar, as here described, 
is 227 feet. The plains of the Canoose Valley and those near Basswood 
Ridge are thus shown to be not far above the highest of the beaches. 


1The Water Power of Maine, by Walter Wells, p. 115, Augusta, 1869. 


SYSTEMS OF GLACIAL GRAVELS. he 


BARING-PEMBROKE SYSTEM. 


A ridge of glacial gravel comes from the north of the northern bank 
of the St. Croix River a short distance west of the bridge of the St. Croix 
and Penobscot Railroad Company, at Baring. Directly opposite, on the 
southern bank, the ridge begins again, and probably it was once continu- 
ous across the bed of the stream; but if so, it has been considerably washed 
away. A series of ridges separated by gaps extends from Baring south- 
ward over a low divide, and thence along the valley of Moosehorn 
Stream. Farther south the system takes the form of a rather continuous 
level-topped plain, which presents the external features of a marine delta- 
plain; but 1 or 2 miles north of Pennamaquan Lake, in Charlotte, the sys- 
tem changes to a series, nearly a mile wide, of broad reticulated ridges 
about 100 feet high, inclosing several deep kettleholes. The gravel passes 
into the northern end of Pennamaquan Lake as a long gently-sloping bar, 
and within 2 miles reappears on the western shore of the lake, and thence 
the series is found along the lake and Pennamaquan Stream to its mouth 
in Pembroke. Toward the south the ridges become shorter and the gaps 
somewhat longer—indeed, some of the ridges are so short as almost to be 
lenticular hummocks. Unless, perhaps, at Pennamaquan Lake and at the 
top of the col in the southern part of Baring, the gaps in this system seldom 
exceed one-fourth of a mile. The country traversed by this system is coy- 
ered by marine clay. An excavation in this gravel ridge made a short dis- 
tance south of Barmg Village showed the ridge to be covered by 3 feet 
of clay containing marine fossils, and a number of bowlders having the 
ordinary till shapes rest on the clay directly above the gravel. 

The northern connections of this system are obscure. D. F. Maxwell, 
a civil engineer of St. Stephen, New Brunswick, reports sand-and-gravel 
deposits in the valley of the Moannes Stream, extending about 4 miles 
north from Baring, and these are probably a part of this system. Gravels 
are reported at Chiputneticook Falls, St. Croix River. Possibly this system 
is a continuation of the Dyer system, but I mark them provisionally as 
independent systems. 


HOULTON-DENNYSVILLE SYSTEM. 


This important osar system appears to begin a few miles north of the 
-divide between the waters flowing northward into the Aroostook River and 


74 GLACIAL GRAVELS OF MAINE. 


those flowing south and east, at an elevation of about 900 feet. In the 
eastern part of T. 9, R. 4, Aroostook County, a two-sided ridge extends 
for about 3 miles along the east side of the Alegwanus or Blackwater 
River, a stream which flows northwesterly into the Aroostook. The ridge 
has rather steep lateral slopes, and is from 10 to 30 feet high. On the sur- 
face it appears to be composed of till, but on diggmg down 2 or 3 feet, 
true water-washed gravel is revealed. The pebbles are only slightly 
rounded, yet the finest débris has been plainly removed by gentle currénts, 
and therefore the deposit is seen to be, not unmodified till, but the residue 
after the action of water has removed the finest portion of the till and has 
rounded and polished the larger fragments a very little. The ridge is here 
composed of fragments of sedimentary rocks, which readily weather near 
the surface of the ground, so as to lose their waterworn surfaces and to 
resemble closely the stones of the upper layers of till. After an apparent 
gap in the system of more than a mile, another ridge is found, extending 
eastward, which is said to reach the northwest corner of Littleton, where 
the system takes a more southerly course to Carys Mills, a short distance 
west of Houlton Village. In this part of its course it several times crosses 
low divides, and thus passes from one valley into another; and there are 
several gaps in the system. 

Prof. C. H. Hitchcock writes concerning this osar as follows:* “A 
short distance west of Houlton the same horseback reappears, bemg m 
one place 90 feet high. The material of the ridge is sand, gravel, and 
bowlders, indistinctly stratified. The sand of this horseback is black, and 
there is no similar sand anywhere else in the county south of Houlton.” 

On the same page is given a figure showing the internal structure of 
the ‘“‘horsebacks.” Occasionally I have observed sections such as that given 
in Professor Hitchcock’s figure, but usually the osars have a more arched 
stratification in the cross section. Not far north of Carys Mills the osar 
extends into a broad ridge or plain, with some reticulated ridges as outlets. 
This great abundance of gravel is found at the southern end of a long slope, 
which, for 25 miles, has an average fall of about 20 feet per mile. The 
pebbles and cobbles are very well rounded at this point, and a much larger 
proportion of them are granitic than at the northern end of the system. 
From Carys Mills the osar continues as a large ridge for several miles, 


1 Preliminary report upon the natural history and geology of the State of Maine, p. 273, 1861. 


HOULTON-DENNYSVILLE SYSTEM. 15 


through Hodgdon, following the south branch of the Meduxnikeag River. 
In Cary Plantation the system turns southeastward, crosses to the east of 
the Calais-Houlton road, and continues southward for several miles in a 
valley nearly parallel with that road. In this part of its course it crosses 
a divide at least 75 feet above Carys Mills, and for several miles in Hodg- 
don it consists of a series of low bars separated by short gaps, in part due 
to erosion. Near the north line of Orient the New Limerick branch unites 
with this series to form quite a large and broad ridge, which is continuous 
till it extends as a long sloping point out into the north end of Grand 
(St. Croix) Lake. The Calais-Houlton road is built for several miles on 
the top of this ridge. Excavations show much sand and gravel, with some 
coarser matter, rounded cobbles, bowlderets, and even a few water-polished 
bowlders. ' In several places the lines of stratification were observed to dip 
quite steeply toward the south. According to the testimony of numerous 
lumbermen and others, a two-sided ridge of gravel extends for long distances 
on the bottom of Grand Lake. In warping rafts of logs down the lake, the 
lumbermen are liable to drop anchor in the yielding gravel; they are then 
obliged to take up the anchor and drop it in the deeper water on each side 
of the ridge, where they report finding a firm ‘“‘clay bottom.” It is uncer- 
tain whether this is sedimentary clay or till. The osar appears on the land 
at several of the capes of Grand Lake, and disappears beneath the water 
while crossing the intervening bays. Thus at Birch Point, Weston, the 
osar runs out as a lone bar for a considerable distance into the lake; and, 
according to report, the small islands, “Billy and Ann,” are composed of 
rounded gravel. If so, they are parts of the osar which rise above the lake. 

The outlet of Grand Lake is from the eastern side, about 5 miles from 
the south end of the lake. The portion of the lake south of the outlet is 
called the ‘“‘Arm of Grand Lake,” and is inclosed between two north-and- 
south ranges of hills. Going south we find these hills approaching each 
other, so that at the south end of the arm they are separated by a narrow 
V-shaped valley, whose sides rise steeply upward several hundred feet. 
One of these hills is called Spruce Mountain. The osar gravel is found for 
several miles along the west side of the Arm of the Lake. At the south 
end of the lake it forms a distinet two-sided ridge, which has been exca- 
vated for road gravel. It is thus revealed that near the axis of the ridge 
finely stratified sand and gravel dips 21 degrees in a nearly south direction, 


76 GLACIAL GRAVELS OF MAINE. 


and this over an exposure 40 feet long and 6 feet high. A small brook 
flows northward into the lake at this point, but it is only about 1 mile in 
length, and could never carry much sediment into the lake; still less could 
it give its sediments a southward dip. The eravel on the beach of the 
lake, as well as the small amount of gravel brought down by this brook, 
has very nearly the till shape, and is nowhere well rounded like the gravel 
of the two-sided ridge at the foot of the lake. It thus becomes evident 
that this ridge is the osar. A short distance south of the foot of the lake 
the ridge becomes low, and the stratified sand and gravel are almost 
covered from sight by a pellmell mass resembling a stony till containing 
numerous till bowlders. But for road excavations one would hardly sus- 
pect the existence of this hidden gravel. 

This till-like mass might be accounted for im several ways. (1) It 
might be due to a landslide; but I could discover no place bare of till, or 
any other sign of a landslip, at least on the lower slopes of the hills. 
(2) It might be due to ice floes stranded at a time when the lake stood 
about 10 or 15 feet higher than at present. Nowhere else on the shore of 
the lake did I discover such proofs of the water having stood at a higher 
level. It must be admitted, however, that the shape of the Arm of the 
Lake is very well adapted to cause a convergence of floes to this place. 
(3) The till may have tumbled down upon the sediment of the glacial 
stream, either into a subglacial tunnel or from the sides into a superficial 
channel. 

My brief visit did not permit me to explore the shore of the lake very 
far. The gravel ridge becomes less conspicuous as we go southward from 
the lake, and disappears within three-fourths of a mile, at an elevation of 
not more than 30 feet above the lake. The ground continues to rise very 
gently for somewhat more than a mile, and then slopes southward down the 
valley of the east branch of the Tomah Stream. The highest part of this 
divide is hardly more than 50 feet higher than the lake. It is certain that 
an osar stream flowed southward from the Arm of Grand Lake through 
this very low pass, where it was for 2 miles or more hemmed in by high 
hills on each side. But the gravel is rather fine and the ridge is not large. 
This indicates a stream of moderate velocity and size. The course of this 
stream must have been somewhere to the south or southeast. Its most 
natural route lay down the valley of the east branch of Tomah Stream, 


HOULTON-DENNYSVILLE SYSTEM. HA 


which crosses the Maine Central Railroad a short distance east of Tomah 
station, but for 5 or more miles I have no note of any glacial gravels. he 
country is a wilderness difficult to traverse, and even large ridges might 
easily escape observation. he difficulty of the search is increased by the 
fact that near the lake the gravel is covered by considerable till, and this 
condition may continue for some miles southward. And if the ridge is not 
large at the south end of the Arm of the Lake, on an up slope, it should be 
expected that on a southward or down slope of 15 or more feet per mile 
the stream would sweep its channel clear of all except the coarsest matter. 
It is thus seen that although glacial gravels could not be found for a con- 
siderable distance, this fact does not, under the circumstances, prove that 
the glacial stream did not flow down this valley. Careful search and inquiry 
failed to show any line of gravels reaching from the foot of Grand Lake to 
Lambert Lake or other point southwestward. 

A mile or two south of Tomah station the two branches of Tomah 
Stream unite, and from this point of junction an exteusive series of reticu- 
lated ridges and broad plains of sand and gravel are found in the valley of 
the main stream, extending to near the mouth of Little Tomah Stream in 
Codyville. These large plains demand the assumption of large glacial 
streams. The Smyrna-Danforth osar river flowed down the valley of the 
west branch of Tomah Stream. This was a larger glacial river than that 
which flowed south from Grand Lake, and while it was competent to have 
brought down the large plains of the Tomah Valley, yet the probable his- 
tory of these plains is as follows: The two glacial rivers, one from the 
direction of Houlton and Grand Lake, the other from Danforth, united 
near where the two branches of Tomah Stream now unite, and together 
produced the sand and gravel plains extending into Codyville. The eleva- 
tion of Tomah station is 370 feet, and I estimate the elevation of the plains 
north of Codyville to be more than 200 feet. The southern part of these 
plains may therefore be a marine delta. 

From near the mouth of Little Tomah Stream the ridge varies from 10 
to 25 feet in height. Its lateral slopes are gentle, thus making it quite 
broad for its height. The ridge crosses the Schoodie River at an elevation 
of 165 feet, and continues southward near the line between Baileyville and 
Princeton. In the southern part of Baileyville and in Alexander the sys- 
tem becomes broken by several gaps while following a rather low pass, 


78 GLACIAL GRAVELS OF MAINE. 


and runs into the north end of Meddybemps Lake at an elevation of 
150 feet.’ 

The southwestern angle of the broad part of this lake is bordered by 
a large peat-covered heath, in the midst of which is a rounded hummock, 
said to be composed of sand and gravel. It rises about 30 feet above the 
peat and is in the line of the gravels; it is probably a part of the system. 
From near the south end of this heath a plain of sand and gravel extends 
southward along the eastern base of a hill which lies parallel with the lake 
and outlet, and about 1 mile west of them. On the north this plain shows 
mounds and low ridges of gravel rising above the surrounding plains of 
gravel. It is here less than one-fourth of a mile in breadth. Going south- 
ward the material becomes finer, the top is more level, and it expands laterally, 
so as to be nearly a mile broad at the point where it is crossed by the road 
leading west from Meddybemps Post-Office. Both the east and west sides 
of the plain here rise steeply above the sedimentary clay and sandy clay 
which flank it, as a narrow border, toward the north at the angle of the lake, 
but toward the south it becomes broader, so as to cover the whole valley 
not far south of Meddybemps Village. Near there the gravel plain becomes 
finer by degrees and rises not so far above the clay, and soon they merge 
into each other and extend as a sheet of marine clay all the way to the sea. 
The plain lying west of the village is thus seen to have the gradations of 
sediments characteristic of the delta when examined lengthwise. Why, 
then, did it not spread outward across the whole valley? From the village 
northward the grayel plain lies about 40 feet above the outlet of the lake 
and the river. Had the ice melted over the whole valley, the gravel plain 
and its bordering clay would have spread across the valley and along the 
shores of the lake, whereas no clay to speak of appears at the lake. This 
can be accounted for only on the hypothesis that at the time the gravel plain 
west of the village was being deposited ice still covered the locality now 
occupied by the eastern part of the lake and the valley of Dennys River 
and as far south as where the gravel and sand delta merge into the marine 
clay. Here was the ice front, and to the south lay the open sea, where the 
finer sediments were spread far and wide. To the north lay a broad chan- 
nelintheice. he elevation of the place where the sea margin then stood was 


'This lake is estimated at 250 feet in Walter Wells’s Water Power of Maine, p. 129, Augusta, 
1869. This was a typographical error. The estimate sent to Mr. Wells by P. HE. Vose, esq., of 
Dennysville, was 150 feet. 


HOULTON-DENNYSVILLE SYSTEM. 719 


140 to 150 feet. The elevation of the sea was certainly as much as this, and 
it may have stood higher, possibly up to its highest level, about 225 feet. 

The local history was probably about as follows: The original narrow 
osar channel in the ice became broadened, and in this broad channel the 
gravel-and-sand delta was deposited. The channel broadened recessively 
northward, and thus the time came when the coarser sediments brought from 
the north were deposited at points considerably north of Meddybemps Vil- 
lage, perhaps as far as the north end of the lake or in the lake. The finer 
sediments were at this time brought down farther, and formed the clays 
bordering the sand plain opposite the village and southward. The time 
must have come when the ice all melted over the valley where the lake now 
is, but by this time the sea had advanced up the valleys of the St. Croix, 
the Schoodic, and the Tomah, so that this great glacial river poured into 
the sea near Codyville, many miles northward. The supply of sediment 
was thus cut off from the north, so that when the open sea at last prevailed 
over all the upper valley of Dennys River and Meddybemps Lake, but 
very little clay was deposited, except where the old river channel had been. 

If, during any of the time the delta west of the village was being 
formed, the sea stood above the level of about 140 to 150 feet, the channel 
of the glacial river was in fact a bay within the ice, where the sea met the 
fresh water. During the time of the summer flood of the glacial river the 
muddy fresh water would fill all this broad channel or bay, but in winter, 
when the glacial waters were scanty, it would be a sort of estuary inclosed 
between walls of ice. As the high tides of that region prevailed, the salt 
water would naturally extend for some distance up the glacial channel, just 
as it does up the rivers of to-day. (This and all other descriptions should 
be read with the map in hand.) 

Southward from Meddybemps the series extends along the west side 
of Dennys River, through Dennysville, and for a short distance into 
Edmunds. It is discontinuous all the way, and becomes more so toward the 
south, until in Edmunds the ridges are only one-third of a mile or less 
in length and not more than one-eighth of a mile in breadth. 

In the southern part of Edmunds and in Trescott are numerous gravel 
beds, which are found on the slopes of hills having a southward or eastward 
exposure. I formerly supposed them to be connections of this gravel 


80 GLACIAL GRAVELS OF MAINE. 


system, but I have since examined several which proved to be beach gravel. 
I therefore provisionally mark the end of this system in the northern part 
of Edmunds. Length from Edmunds to T. 9, R. 4, 115 miles.* 


NEW LIMERICK-AMITY BRANCH. 


This branch extends from near the center of the town of New Lim- 
erick through Linneus, Cary Plantation, and Amity, and joins the Houlton 
branch near the north line of Orient. ‘Toward the north this osar is quite 
continuous and prominent, with conspicuous meanderings. Southward it is 
somewhat interrupted by short gaps. It traverses a rolling plain, and sev- 
eral times passes from one valley to another over a low divide. South of 
where this and the Houlton branch unite, the ridge is larger and more con- 
tinuous than is either branch for several miles north of their junction. The 
average size of this branch is about as large as the Houlton branch, though 
it does not expand to so great size as the latter at Carys Mills. Length, 


about 20 miles. 
SMYRNA-DANFORTH BRANCH. 


Measured by the amount of gravel which the Smyrna-Danforth glacial 
river deposited, it deserves to be classed as the main tributary and the 
Houlton River as a branch. According to this nomenclature, the system 
ought to be known as the Smyrna-Dennysville system. But, on the whole, 
there are such advantages in considering the longer tributary as the main 
river that the Houlton branch has been considered the main one, although 
it is by no means certain that a careful exploration will not show the 
Smyrna branch to be longer than that which passes near Houlton. 

The other connections of the Smyrna series are uncertain. A ridge of 
gravel, probably glacial, is reported as being found a short distance south 
of St. Croix Lake. The divide between the Masardis River, flowing north- 
ward, and the east branch of the Mattawamkeag is so level that the waters 
of one stream have been diverted into the other by a ditch. The valleys 
of these two streams thus form a continuous valley with slopes favorable 
for a long osar system to extend from the vicinity of Masardis south and 
eastward to Smyrna. I crossed the Masardis River in the No. 9 townships 
and explored its valley for several miles, but no gravels were found near 


17 am indebted to Mr. John C. Carpenter, of Houlton, for much valuable information relating 
to the gravels of Aroostook County. 


——— 


SMYRNA-DANFORTH BRANCH. 81 


the river. The forest is so dense, however, that one could easily miss a 
gravel system unless following it lengthwise. In T. 9, R. 5, several short 
ridges of true glacial gravel are found a few miles west of the Masardis 
River, and it is not impossible that they are part of a series extending past 
St. Croix Lake to Smyrna. 

From near Smyrna Mills the gravel series takes the form of a nearly 
continuous and rather flat-topped plain of sand and gravel following the 
east branch of the Mattawamkeag to Haynesville. In places the plain, 
before being eroded by the stream, extended across the whole of the rather 
narrow valley. The river sometimes flows at one side of the gravel plain, 
but more often it has eroded the central part, thus beig bordered on each 
side by terraces of erosion. Sometimes it has cut out two channels, leay- 
ing a central ridge uneroded. It will thus be seen that the alluvium con- 
tained in the narrower parts of the valley presents the external features of 
ordinary valley drift. The material of this alluvial plain is in general 
composed of sand and fine gravel, but with a mixture of larger pebbles, 
cobbles, and some bowlderets. The stones are much rounder than those 
found in the beds of the other streams of this region, and must have been 
subjected to much greater attrition. In some places the valley broadens 
considerably. Here the gravel plain does not widen correspondingly, so 
as to fill the whole valley, but sometimes is bordered on the side away from 
the river by a steep bank downward, which, so far as I could determine, is 
not due to erosion. he alluvial plain of highly rounded matter is thus 
shown to be of glacial origin, and not a plain of ordinary river drift. Its 
breadth varies from a few rods to about one-fourth of a mile. This plain 
is a good instance of what I have elsewhere named the osar-plain, or broad 
osar. 

Not far north of Haynesville this series is jomed by another series, 
from Island Falls. At Haynesville the gravel forms a single plain about 
one-eighth of a mile broad, which shows that the two tributary glacial 
rivers here flowed as one. ‘The two branches of the Mattawamkeag River 
also unite not far north of Haynesville to form the main river. ‘The river 
here flows in a broad and quite level valley. For 4 miles southeast of 
Haynesville an osar-plain of sand and gravel extends along the axis of the 
valley, bordered by a plain of horizontally stratified sand and silt, one-half 


mile or more wide. In many places this sand has blown into low dunes. 
MON XXXIV——6 


82 GLACIAL GRAVELS OF MAINE. 


Excavations not in the dunes show the sand overlying the till and till 
bowlders. This bordering sand plain has the external features of valley 
drift. At the great bend, or “oxbow,” of the Mattawamkeag the river 
makes an abrupt turn from a southeast to a southwest course. The osar- 
plain here leaves the river valley and goes on southward through Weston 
to Danforth. The character of the alluvium of the Mattawamkeag Valley 
here changes. Below this point the river shows an alternation of long 
reaches of dead water separated by short rapids or falls. Along the level 
parts of the valley the river drift consists of clay and silt, with sand, sub- 
angular coarse gravel, and even bowlderets and bowlders at the rapids. 
The rapids are found at places where the ice-sheet left deep masses of till 
spread across the valley. The only gravel found in the valley below the 
oxbow is the result of the river’s eroding the till, and the shapes of the 
stones are very different from those of the osar-plain in Haynesville. 
True, some rounded stones can be found in the bed of the river, or as a 
part of the lowest terrace, for some miles below the oxbow, but they were 
probably washed down from the osar-plain, although I could not prove them 
to be contemporaneous with it or with any of the higher terraces. The till 
ridges left across the valley of the Mattawamkeag must originally have 
caused a series of lakes to form in the valley directly after the melting of 
the ice. The broad sand plain found bordering the osar-plain proper in 
Haynesville might thus be a lake delta if a till barrier high enough to form 
a lake at that level existed. Thus far I have found no barrier high enough 
for the purpose. Concerning the broad plains of the Mattawamkeag 
Valley extending from Haynesville to the oxbow, it is safe to conclude, 
first, that the sand-and-gravel plain near the center of the valley is a true 
osar-plain; second, that the bordering plain of sand was probably deposited 
in a still broader channel within the ice, making it in fact a glacial lake; 
yet there is nothing in its form to disprove the hypothesis that it was formed 
in an ordinary lake if a till barrier (now cut through by the river) of suffi- 
cient height can be found; or it may possibly be an overwash or frontal 
plain deposited when the ice had retreated a little north of Haynesville. 

A plain of sand and fine gravel extends from the great bend of the 
Mattawamkeag southward through Weston. It is one-eighth of a mile or 
more wide, and ascends the valley of a small brook which flows northward. 
The stream has excavated numerous terraces of erosion in the osar-plain. 


SMYRNA-DANFORTH BRANCH. 83 


The plain is quite continuous on the northern slope until it reaches a height 
of 75 or 100 feet above the Mattawamkeag River. It then is somewhat 
discontinuous while passing over a divide, and then it takes the form of an 
osar-ridge from 15 to 40 feet high, containing much coarse matter, very 
round cobbles, and some bowlderets. The ridge continues southward for 
several miles, and then, making a beautiful curve to the left, it turns south- 
eastward and crosses the Baskahegan Stream about 1 mile north from Dan- 
forth Village. It follows the western bank of this stream through Danforth 
Village, and then, leaving the Baskahegan Valley, which lay directly 
before it, it turns more to the eastward along the valley of Crooked Brook. 
It goes up this valley and over a divide near Forest station, and thence 
_ follows the valley of the west branch of Tomah Stream to its junction 
with the Houlton osar, not far south of Tomah station. Between Danforth 
and Tomah stations of the Maine Central Railroad, this great gravel system 
follows the same valley or pass as that followed by the railway. About 
one-fourth of a mile northeast of Danforth Village there is a small hillside 
kame at nearly right angles to the main osar. It slopes rather steeply down 
a hill for nearly one-eighth of a mile and disappears. It was evidently 
deposited by a small lateral tributary of the main glacial river. The gravel 
comes to an end within one-fourth of a mile from the main osar. Near 
Danforth the gravel is fine enough to serve as railroad ballast. Going 
eastward up the slope, we find the material becoming coarser, and at the 
top of the divide at Forest station the ridge consists almost wholly of large 
pebbles, cobbles, and bowlderets. East of this point the valley of the 
west branch of the Tomah Stream has a fall of about 30 feet per mile 
southeastward, and for about 3 miles east of the col the gravels are very 
scanty and difficult to trace. Apparently on this steep down slope the force 
of the glacial river was such as to sweep before it all but the larger 
bowlderets and bowlders. The valley is one of the dreariest bowlder fields 
in the State. The rounded gravel becomes easily traceable at a point 
about west of Tomah station, and so continues down the valley, soon 
expanding into the plains north of Codyville, as before described. To these 
plains this tributary probably contributed much more material than the 
Houlton branch. 

The most noteworthy features of this important gravel series are the 
following: For a considerable part of its course it takes the form of a plain 


84 GLACIAL GRAVELS OF MAINE. 


with rather level top in the cross section. When traversing narrow valleys, 
this plain appears like valley drift, but is distinguishable from it by the 
very round shape of the pebbles, by its greater size than the valley drift of 
the region, by the larger size of its stones, by the fact that it does not 
always spread laterally to fill the valleys in which it is situated, and, still 
more conclusively, by its going up and over hills. While crossing the 
lower ground the material is rather fine, approaching the top of hills it: 
becomes coarser, and on a steep down slope it is scanty or absent for a mile 
or more. In Haynesville the osar-plain proper is flanked by sand plains. 
Apparently the osar was first deposited in a channel one-eighth to one- 
fourth of a mile wide. This was situated north of a hill 75 or 100 feet 
high, and the water must have been at least of that depth in order to flow 
southward over the hill) Subsequently this channel was widened by lateral 
melting of the ice, until it became one-half mile or more wide and approxi- 
mated the condition of a lake 75 or more feet deep. In this a plain of 
fine sand was deposited at the flanks of the central plain of gravel. This 
plain has subsequently been somewhat modified by the winds and by the 
floods of the Mattawamkeag River, and to that extent is valley drift. No 
30 miles of any other osar of eastern Maine at such a distance from the 
coast has so great a cubic content as this series for the 30 miles north of 
Danforth. 
Length, about 45 miles. 


ISLAND FALLS BRANCH. 


A nearly continuous osar extends from Merrill Plantation southward 
near the line between Dyer Brook and Hersey to the village of Island 
Falls, and thence southeastward along the western shore of Mattawamkeag 
Lake and the west branch of the Mattawamkeag River, and joins the 
Smyrna branch a short distance north of Haynesville. In some places, 
especially toward the south, the gravel widens so as to approach the form 
of the flat-topped osar-plain, but for most of the distance it takes the form 
of a two-sided ridge with arched cross section. 

Since the Smyrna and the Island Falls tributaries are near each other 
and are at equal distances from the sea, and penetrate regions having similar 
rocks and topography, they throw light on each other’s origin. ‘The pebbles 
are no rounder in the osar than in the osar-plain. The Stones in both are 


MARION AND BAST MACHIAS. 85 


largely made up of granite, slates, and the harder sedimentary rocks, and 
in both are much rounder than the stones of the streams of this region not 
in the lines here indicated for the glacial gravels. These points had to be 
carefully studied before it became evident that the plain of rounded gravel 
situated in the valley of the east branch of the Mattawamkeag between 
Smyrna and Haynesville, where the slope of the river coincided with that 
of the glacial stream, was really an osar-plain and not ordinary valley drift. 


LOCAL KAMES IN MARION. 


A short kame is situated on the east side of Rocky Brook in the 
northern part of Marion. Another is found near the southeast angle of 
the northern division of Gardners Lake. It is a narrow ridge rising 15 to 
20 feet above the marine clay, and is about half a mile long from east to 
west. It has the direction of a terminal moraine, but appears to consist 
wholly of water-washed gravel. 

On the western side of the long point of land which projects from the 
eastern shore of Gardners Lake, so far as almost to divide the lake into two 
separate lakes, is a broad ridge or plain of rounded gravel and cobbles. It 
has been eroded by the waves on its western side so as to form a prominent 
beach cliff. 

These gravel deposits of Marion do not appear to have been formed 
by a single glacial stream, and therefore they are not classed as a system. 
There are many old beaches in Marion on hills that would be exposed to 
the surf while the sea stood at higher level than now. 


EAST MACHIAS SYSTEM. 


This system begins abruptly in T. 18 near where the road from Kast 
Machias to Crawford is intersected by the road leading west from Dennys- 
ville. The gravel here takes the form of a single two-sided ridge 10 to 30 
feet high. Going southward we here and there find two or more ridges 
inclosing kettleholes, and then the gravel soon becomes discontinuous. 
Still farther south the gaps become longer and the gravel ridges shorter, 
until the system ends as a series of small rounded hummocks or cones, 
separated by intervals of from one-eighth to one-half a mile. The last of 
the gravel hillocks which I could find was a short distance south of Kast 
Machias Village. South of this point were a low pass and a plain covered 
by marine clay. Although the system ends several miles north of the open 


86 GLACIAL GRAVELS OF MAINE. 


sea, yet the end is only a few feet above tide water. ‘Toward the north the 
ridges of this system are broad and massive, with gentle side slopes. The 
stones are well rounded throughout the whole length of the system, and 
among them are a multitude of bowlderets and bowlders, up to 3 feet in 
diameter. It lies on a southern slope favorable to the flow of the water 
until the ice was nearly all melted. Its course is quite free from meanders. 
The elevation of the northern end is not precisely known, but the glacial 
stream, at the time the sea stood at 230 feet, would flow into it not far from 
the north end of the system. This is where the broad, almost plain-like, 
ridges, inclosing kettleholes, are found. The large size of the bowlders 
in this system makes it quite probable that this was the work of a subglacial 
river. 
Length, about 10 miles. 


CRAWFORD SYSTEM. 


A short deposit of glacial gravel is found about 2 miles north of Craw- 
ford Church, in a low valley leading south from Crawford Lake. This val- 
ley contains a small brook which flows northward and has partially eroded 
the kame, though the brook is but little more than half a mile long. A 
valley leads over a low divide from this pomt southward, but no gravels 
have been found near the height of the pass. Directly in front of this pass, 
toward the south, is a plain of sand and gravel about one-fourth of a mile 
in diameter. It is situated near the northwestern angle of Love Lake, in 
the southern part of Crawford. The plain is rather level on the top, and 
the material is finer toward the south. It rises steeply above the surround- 
ing till to a height of from 6 to 15 feet. It thus has every appearance of a 
delta. Its elevation above the sea is probably from 250 to 300 feet. No 
marine clay appears below this point, and I regard the plain as having been 
deposited in a small glacial lake. Near the southwestern angle of Love 
Lake there is another and longer gravel plain, and from that point a some- 
what discontinuous two-sided ridge extends southward into Ts. 19 and 20. 
It is for several miles nearly parallel with the outlet of Love Lake. At 
the road from Crawford to East Machias it leaves this valley, and the road 
is made upon it for about 1 mile south, when the system bends southwest- 
ward. It is said to end in a level sand-and-gravel plain near the East 
Machias River, not far south of Round Lake. 


CRAWFORD SYSTEM. 87 


The map shows that this gravel series is nearly in the direction of the 
East Machias system prolonged northward. Several small ridges of sub- 
angular glacial gravel are found intermediate between the two systems. 
They are in T. 18, near the road from Crawford to East Machias. They 
are found on the western slopes of the rather high hills which border the 
valley of the East Machias River on the east. heir course is westward 
down the hills, and I regard them as short hillside kames deposited by 
small glacial streams which were either lateral tributaries of a large glacial 
stream in the valley or flowed into the sea at the time it extended far north 
in the valley of the East Machias River. This valley is very inaccessible, 
and my exploration was confined to the region lying near the road from 
East Machias to Crawford. 

According to my present information, it would appear that the glacial 
and postglacial history of the broad and plain-like valley of the East 
Machias River is about as follows: 

None of the longer glacial rivers flowed through this valley, the drain- 
age of the glacier to the north being either carried off eastward by the 
Dennysville system or westward down the valley of the Machias River. 
The East Machias system of glacial gravels was wholly deposited before 
the melting of the ice, unless the enlargement of the system before described 
as being found about 2 miles from its northern extremity prove to be a 
marine delta. At the time the ocean stood at the contour of 225 feet, an 
arm of the sea 3 to 5 miles broad extended northward up this valley to 
Crawford, and probably was continuous with the bay of salt water which 
at that time extended up the valleys of the St. Croix and Schoodice rivers 
to Princeton. The Crawford-Love Lake system was deposited later than 
the East Machias system, at a time when the ice had receded so far north- 
ward that all the valley from Round Lake southward was covered by the 
sea. Occasional gravel deposits have been reported in the valley near the 
river, but the descriptions make it uncertain whether they are glacial gravel 
or till. A ridge of true glacial gravel crosses the Air Line road from Calais 
to Bangor in the southwestern part of Crawford. It is near the East 
Machias River, and is about a mile long. Another short and rather broad 
ridge is found not far to the south of it. This series ought to end at the 
south in a delta, but I have not been able to find one, unless it be the 
shorter ridge just mentioned. This short series is evidently an incident in 


88 GLACIAL GRAVELS OF MAINE. 


the retreat of the ice northward, and the glacial stream which deposited it 
was soon terminated by flowing into the sea. 


WILDERNESS REGION NORTH OF COLUMBIA, COLUMBIA FALLS, AND 
JONESBORO. 


We now approach a region very difficult to investigate. The gravel 
deposits situated in it are vast, being equaled only by the great plains of 
the southwestern part of the State. The western part of Washington County 
and the eastern part of Hancock County are mostly wooded. There are 
many swamps impassable in summer or penetrated with difficulty. There 
are only four continuous east-and-west roads crossing the great region lying 
south of the railroad from Mattawamkeag to Vanceboro. These roads I 
have traversed, and have penetrated the wilderness in several other direc- 
tions. In addition, I have derived much information from lumbermen and 
explorers and from three experienced land surveyors—Mr. F. I. Campbell, of 
Cherryfield; Mr. J. R. Buckman, of Columbia F alls, and Mr. H. R. Taylor, 
of Machias. I am indebted to Mr. Taylor for quite an elaborate map of 
this region. As a result of my observations and inquiries, it is hoped that 
the map (PI. LI) contains all the larger systems of glacial gravel, but as to 
the details of their courses much remains to be done. 

The sea at one time extended northward up the Machias Valley to the 
Air Line road from Calais to Bangor, in Wesley, and probably a few miles 
farther. Machias Bay was then a pretty broad body of water, in places 10 
or more miles broad. This gave great force to the waves, and sea beaches 
are found as far north as Wesley. ‘The necessity of distinguishing these 
beach gravels from the glacial gravels in this wooded country, where the 
whole is often disguised by marine clays and the peats of swamps, compli- 
cates considerably the problem of the drift of this valley. The till is very 
heterogeneous in its composition, fragments of slates, schists, and granite 
being rather indiscriminately mixed. he granite is partly derived from 
local bosses of that rock which rise in the midst of the slates and schists, 
but chiefly from the great area of granite which extends from Orland to 
Aurora and thence northeastward past the region of the great Schoodic 
Lakes. Heaps and trains of granite bowlders abound. Many of the 
granite stones of the till are so rounded by the glacial attrition that it often 
requires close study to distinguish the till from a slightly water-washed 


WILDERNESS REGION. 89 


glacial gravel. I have in the past been obliged to change my views con- 
cerning some of these formations, yet, in spite of all the difficulties, enough 
is known to mark the region as a very interesting one. The map shows 
several of the longer osar systems of the State converging toward an area 
10 or 15 miles broad (from east to west) lying in Columbia, Columbia 
Falls, and Jonesboro. Over a very large area there is a convergence of 
the glacial strise toward a north-and-south line passing through the same 
place. At several other places on the coast there are converging stri, but 
they are shown in small areas where only the scratches last made converge. 
It thus appears that in these cases the convergence took place only during 
the final retreat of the ice. But in the Columbia-Jonesboro region all the 
scratches converge, the later ones more than the earlier ones. It is thus 
shown that, like the Greenland glaciers of to-day, the ice-sheet did not 
advance with an equal rate of flow in all parts, but that the snow fields of 
the interior parts of the State were discharged more rapidly along certain 
belts, which made them practically glaciers of limited breadth, confluent, 
however, with more slowly moving ice. A stream of ice about 10 miles 
wide here served as the outlet of an area which broadened toward the 
north to 30 and perhaps 50 miles, and doubtless its rate of flow was corre- 
spondingly rapid. An observer off the coast during the Ice period would 
have seen a greater number of icebergs from opposite this place than else- 
where. It is difficult to account for the convergence to so narrow limits by 
the surface features of the land. The area between the Big Tunk range of 
hills lymg west of Cherryfield and the hills of Marshfield is a gently rolling 
plain, with only here and there a hill rising more than 100 feet. It would 
be very natural for the ice to be wedged in between these ranges of hills, a 
distance of 25 miles. Instead, the ice abandoned the level valley of the 
Narraguagus River, which extends for 15 miles east of the Big Tunk 
Mountain, and crowded eastward toward Columbia. So also the deflection 
westward extended as far east as Marion, 10 miles east of the Marshfield 
Hills. The central line toward which the strize converge passes near Jones- 
boro Village, and the lines of striation, if prolonged, would meet at a point 
in the sea several miles south of the most projecting point of the coast. 
I have not been able to determine whether there is any deep channel of 
the sea south of Jonesboro or other features causing this remarkable con- 
vergence of glacial flow. It was certainly determined by causes to a 


90 GLACIAL GRAVELS OF MAINE. 


considerable extent independent of the surface features of the present land, 
perhaps by the outline of the ice front in the sea off the coast. 


WESLEY-NORTHFIELD SYSTEM. 


Wesley Post-Office is situated on a range of hills about 200 feet high. 
Along the western base of this hill is a rather low north-and-south valley, 
in which lies a series of ridges of glacial gravel. The system may have 
connections northward toward Chain Lake, but I have traced it unmistak- 
ably only to a point about half a mile southwest of Wesley Post-Office. 
Beds of apparently water-washed gravel are found about 2 miles west of 
Wesley, but it is uncertain how much of them is glacial gravel and how 
much is beach gravel. In view of the doubt, I omit them from the map. 
The series above described as beginning near Wesley extends southward in 
a nearly straight line to Lower Seavey Lake, where it turns southwestward 
and soon spreads into a series of reticulated ridges melosing kettleholes. 
Going southwestward the ridges become broader and the kettleholes more 
shallow, and it soon appears to be a marine delta-plain. _ This series is said 
to connect with the Old Stream series in Centerville and Whitneyville. 

Length, about 15 miles. 


TOPSFIELD-OLD STREAM SYSTEM. 


This important osar system appears to begin not far north of Musquash 
Lake, in Topsfield. At the road from Topsfield west to Springfield the 
gravel takes the form of a low terrace on the west side of the outlet of 
the lake. It consists of well-rounded gravel, and is distinguished from 
valley drift partly by the shape of the stones and partly by appearing on 
one side of the valley with no corresponding terrace on the other side; and 
often it takes the form of a two-sided ridge while following the valley of 
Musquash Stream. It is somewhat discontinuous, and for part of its course 
takes the form of an osar-plain that once extended across the valley, but is 
now deeply eroded into terraces by the stream. The material is rather fine, 
and the size of the deposit is in general not very large. In the southern 
part of the valley of Musquash Stream it becomes a ridge 20 to 40 feet 
high, with moderately steep lateral slopes. For several miles in the midst 
of a low level region it rises above the swamps like a railroad grading. 
The matter here is coarser, and many cobbles and large pebbles appear, all 
well rounded. <A short distance west of where Musquash Stream empties 


TOPSFIELD-OLD STREAM SYSTEM. 91 


into Big Lake, there is a thin sheet of gravel on a gentle slope rising but a 
few feet above the lake. This gravel lies a full half mile south of the 
osar. The stones are distinctly water-polished, though differing little from 
tillstones in shape. This deposit is an old beach, either marine or lacustral. 

The osar leaves the Musquash Valley about a mile north of Big Lake 
and takes a nearly straight course southwestward. It. is easily traceable for 
several miles along the northwestern shore of Big Lake, often forming the 
beach. The gravel reappears on the southwestern shore of the lake, 
between Little River and Little Musquash Stream, and continues its south- 
westward course for several miles along the valley of Little River. It then 
crosses a low divide and extends for many miles southward along Old 
Stream, expanding into extensive plains of reticulated ridges near the Old 
Stream Lakes. The sand and gravel plains extend to the junction of this 
stream with the Machias River, and toward the south are quite level on the 
top and present the appearance of a marine delta-plain. 

A series of discontinuous and rather flat-topped plains or broad ridges 
extends from neaz Masons Bay, Jonesboro, northward into Centerville. 
They appear to be marine delta-plains, deposited not in the open sea but 
in bays receding backward into the ice. They are probably a continuation 
of the Topsfield-Old Stream system. 

The extensive marsh region penetrated by this gravel system is under- 
lain in considerable part by sedimentary clay. Big Lake is 189 feet above 
high tide. Hence, when the sea stood at 225 feet, a sheet of salt water 
must have extended up the valley of Schoodic (also called Kennebasis) 
River to a point a short distance west of Big Lake, and at an elevation of 
about 36 feet above the present level of the lake. The region around the 
lake, especially toward the south and southwest, is so low that a body of 
water of that elevation would be very much larger than the present lake. 
The divide between Little River and Old Stream is low, but probably not 
low enough for an arm of the sea to have extended from Big Lake down 
the Old Stream and Machias valleys. The region overgrown with pine 
near Clifford Lake, which I formerly supposed was covered with glacial 
gravel, now appears to owe its sand and gravel to the action of the waves; 
they are probably beaches of that period. There is an enlargement of the 
osar near the northwestern angle of Big Lake. Part of this appears to be 
a small delta. If so, the history of the Topsfield-Old Stream glacial river 


92 GLACIAL GRAVELS OF MAINE. 


appears to be as follows: First, the main glacial river flowed on to the sea 
near Jonesboro. As the ice retreated, a series of small deltas were formed 
in bays or lakes within the ice. The great delta-plain in T. 25 and in 
Wesley was formed when the ice had retreated so far up the Machias 
Valley that the glacial river carried its sediments beyond the ice front into 
the open sea. Finally, when the sea stood at about 230 feet, the ice had 
melted so far to the northward that a bay of salt water occupied the basin 
of Big Lake. The glacial river, now greatly reduced in size, poured into 
the sea near the northwestern angle of Big Lake, and perhaps subsequently 
at another point a few miles northward in the Musquash Valley. These 
apparent deltas near Big Lake may have been deposited in purely glacial 
lakes, yet they bear a suggestive relation to the old sea-level in the basin 


of the lake. 
GRAND LAKE OSAR. 


At the foot of the outlet of Grand (Schoodic) Lake a well-defined osar 
extends northward into the lake and can be seen for some distance on the 
floor of the lake. The stones are so well rounded that it seems probable 
the series extends north or northwest of this point, perhaps to Oxbrook 
Lake. 'The ridge extends southward from Grand Lake Stream and joins the 
main system in the valley of Little River. Not far from the lake the ridge 
consists of very coarse matter. The large size of the bowlderets and 
bowlders makes it probable that the ridge was deposited by a subglacial 
stream. The upper Schoodic Lakes lie in the midst of a granite region 
which has contributed a great number of stones and bowlders to the drift. 
The vast quantities of granitic drift contained in the great gravel plains of 
Hancock and Washington counties came chiefly from the long outcrop of 
granite which extends from Orland on Penobscot Bay with but few inter- 
ruptions through New Brunswick to Chaleur Bay. 


FARM COVE GRAVELS. 


Farm Cove is a deeply reentering bay on the south shore of Grand - 
Lake. From the head of the cove a low pass extends southeastward, 
bordered by high hills. The highest point of the pass rises but a few feet 
above Grand Lake, and within less than a mile from the lake a branch of 
Little River takes its origin and flows southeastward. Water-washed gravel 
is reported in this valley. The present outlet of Grand Lake is cut through 


BANCROFT-GRAND LAKE SYSTEM. 93 


amass of till, and it is possible that before the barrier was eroded the lake 
stood at a high enough level for the waters to discharge from Farm Cove 
southeastward. If so, these gravels are partly, perhaps wholly, valley 
drift. I have not personally explored this series. It is provisionally 
included among the glacial gravels. 


BANCROFT-GRAND LAKE SYSTEM. 


An osar crosses the Maine Central Railroad about a mile west of 
Bancroft station. The gravel is somewhat rounded, but not enough to 
indicate that the ridge extends very far to the north. It has not been 
explored in that direction, and probably extends only a few miles. With 
numerous gaps the gravel takes a southeast course across the valley of 
the Mattawamkeag River, thence over a low divide and obliquely across 
the valley of Hawkins Brook, then over another low pass into the valley 
of Hot Brook. It then turns more nearly southward, and near the Hot 
Brook Lakes it expands into a plain about one-third of a mile wide. Part 
of this plain has the external appearance of a delta, and was probably 
deposited in a small glacial lake, such as would naturally form on a north 
slope. Thence the gravel system goes south along the valley of the east- 
ern branch of Hot Brook. At the road from Danforth to Prentiss the 
gravel takes the form of a.low osar-plain in the bottom of the valley. 
This has been eroded by the stream into terraces, so as to appear like 
valley drift, but the stones are much more rounded than the till gravel 
which appears in the beds of small brooks in that part of the State. Cross- 
ing a divide said to be much less than 200 feet above the Hot Brook Lakes, 
the gravels turn southeastward over a rolling region to near the northwest- 
ern angle of Baskahegan Lake. In this part of its course the gravel is 
somewhat interrupted. It next turns southwestward through Kossuth to 
Pleasant Lake, crossing the valleys of several streams and as many low 
divides. In this section it is a two-sided ridge, and is not quite continuous. 
It would be contrary to general analogy for this long osar stream to have 
ended so far from the sea as Junior Lake. Rounded gravel, in the form of 
ridges and terraces, is reported along Junior and Scragely lakes, which I 
infer are part of this system. They appear only at intervals, and probably 
a large part of the gravel is beneath the water. The gravels are well 
developed along the western shore of Grand Lake, and thence they 


94 GLACIAL GRAVELS OF MAINE. 


continue southward along Pocumpus and Wabos (or Wabosses) lakes, to 
near the south end of Machias Third Lake. The accounts as to its course 
from this point south are conflicting. According to some accounts the 
gravel continues southeastward and unites with the Topsfield system near 
the head of Old Stream; according to others the gravel is nearly contin- 
uous down the Machias Valley, part of the way keeping back from the 
river. On general grounds the latter appears to be the more probable 
course of this large glacial river, since the great ‘“Mont Eagle plains” and 
the ‘‘Raceground” demand a large and long river as their origin. But 
whatever doubts attach to the course of this system in the vicinity of 
Machias Second Lake, there is no doubt that a system of gravels extends 
from Machias First Lake southward along the west side of the Machias 
River, expanding into a broad series of plains in T. 30, known to the deer 
hunters as the ‘““Raceground.” The part of these plains near the Air Line 
road (Calais to Bangor) is very level and is a delta-plain. Sedimentary 
clays cover the valley of the Machias River all the way from this point to 
the sea, which makes it probable that the southern portion of the Race- 
ground is a marine delta. The glacial gravels continue southward over < 
gently rolling plain and cross the Mopang River, where they expand into 
an extensive series of sand and gravel plains, known as the “Mont Eagle 
plains.” These plains are reported to contain in places kettleholes and 
ridges, while in general they are quite level on the top. This indicates 
that in part at least the Mont Eagle plains are a marine delta. In regard 
to the section extending from this point to the road from Columbia Falls to 
Jonesboro my information is quite conflicting. The map shows the system 
as extending past Libby Lake and becoming discontinuous toward the 
south, ending near Masons Bay, Jonesboro. The plains in Columbia Falls 
and Jonesboro are in general quite flat on the top, and show much coarser 
matter on the north and west than farther south and east. This indicates 
that in part, if not wholly, they are delta-plains, deposited im reentering 
bays in the ice or in glacial lakes. 
Leneth from Bancroft to Masons Bay about 85 miles. 


SISLADOBSIS-PLEASANT RIVER SYSTEM. 


All my informants are agreed that a ridge or horseback of gravel 
extends from Sand Cove at the south end of Sisladobsis Lake nearly south 


SEBOOIS-KINGMAN-COLUMBIA SYSTEM. 95 


to Machias Fourth Lake. From this point southward I have followed in 
great part the information given by H. R. Taylor, C. E., of Machias, and 
the late Hon. 5. F. Perley, of Naples. As mapped, the system runs near 
the town lines east of Sabao Lake and the large Mopang Lake, and 
appears to end near Pleasant River Lake. I crossed this system on the 
Air Line road in 1878, but could not at that time distinguish the plains as 
a delta. My information concerning the Pleasant River Valley south of 
the lake of that name is meager and conflicting. As seen from Columbia, 
the valley appears to have a gentle slope and to be covered with marine 
clay for a long distance northward. It seems probable, therefore, that the 
plains near Pleasant River Lake end at the south in a marine delta— 
at least that would account for the system’s ending so far from the sea. 

As to the region between Sisladobsis and Nickatous lakes, I have 
received much information from Messrs. James Belmore and S. W. Hay- 
cock, of Calais; also from D. F. Maxwell, C. E., of St. Stephen, New 
Brunswick; A. J. Darling, of Enfield; John Gardner, of Robbinston, and 
many others. All agree that in that region there are large tracts of sand 
and gravel overgrown with “Norway pine.” These are probably glacial 
gravels, but my informants locate them with reference to streams and lakes 
not on the existing maps, and therefore it is impossible for me to map them 
even approximately. 

Within 30 miles from Machias are perhaps the most noted grounds for 
the hunting of deer to be found in the older portion of the United States. 
The “Raceground” is so called because favorable to the chase. These 
great plains are due to the large glacial rivers which poured into the sea, at 
a time when the Machias Valley as far north as the Air Line road was 
covered by a broad sheet of salt water. 


SEBOOIS-KINGMAN-COLUMBIA SYSTEM. 


A short ridge of glacial gravel is found in Oxbow Township, Aroos- 
took County, and several similar ridges are reported along the upper 
Seboois Lakes. It is as yet uncertain whether they have any connection 
with the remarkable system now to be described. An osar of unknown 
length comes southward out of the woods to the north shore of Seboois 
Second Lake in T. 7, R. 7, Penobscot County. It enters the water ou 
the north side of the lake and reappears on the south shore, and thence 


96 GLACIAL GRAVELS OF MAINE. 


extends south for several miles along the west side of the Seboois River 
to the road leading from Patten northwestward to Seboois farm and Cham- 
berlin Lake. It is here in a valley of natural drainage continuous (by the 
Seboois and Penobscot rivers) all the way to the sea. But the osar leaves 
this open valley and turns abruptly eastward. The road just mentioned is 
made on top of the osar for a half mile or more, when the road turns 
southward while the ridge keeps on eastward, up the valley of Hot Brook, 
then over a low divide, and down the valley of Hay Brook, to Upper Shin 
Pond. Here it rejected another slope of natural drainage, crossed the 
pond, and then went over a low divide into the valley of Peasley Brook. 
It then turns south and follows the valley of this brook to its junction with 
Fish Stream, about 1 mile west of Patten. In this valley the gravel takes 
the form of an osar-plain, extending across the valley or forming a flattish- 
topped terrace on one side. From near the junction of Peasley Brook and 
Fish Stream a low valley extends for several miles southward, cut off on 
the south by hills about 200 feet high. Rejecting this valley, the osar 
river turned nearly a right angle eastward, and for several miles follows 
the valley of Fish Stream. Its course lay through Patten Village, but 
there is a short gap in the gravel deposits at that place, so that a traveler 
on the north-and-south road sees no signs of the system. About 4 
miles east of Patten, in Crystal, the gravel (here in the form of a two-sided 
ridge) turns another right angle quite abruptly and goes south and south- 
west across the 1,000-acre bog. This bog lies near the top of the low and 
level divide between the waters of Fish Stream, flowing north and east 
into the west branch of the Mattawamkeag at Island Falls, and those of 
the Molunkus River, flowing south. Here the gravel takes the form of low 
bars and narrow osar-plains, flanked and often nearly covered by peat and 
water. The drift of the upper Molunkus Valley merits study. No two- 
sided ridges appeared at the places examined by me, but the river is 
bordered by low terraces which have the form of erosion terraces of 
ordinary valley drift. An inspection shows that the stones of this gravel 
are all well rounded, much more so than the ordinary stream gravel in 
that part of the State. We know, too, that a large glacial river flowed 
into the upper end of this valley, and it is also certain that such a river 
flowed in the southern part of the valley. The river therefore must have 
flowed the whole length of the valley. But the only water-washed gravel 


! 
: 


SEBOOIS-KINGMAN-COLUMBIA SYSTEM. 97 


found in the upper part of the valley is that plain near the stream having 
the form of a sheet of valley drift extending across the whole of the valley. 
From these considerations and the very round shape of the stones it appears 
that the gravel along the Molunkus for several miles south of Sherman is 
an osar-plain and not ordinary valley drift. The gravel follows the 
Molunkus through Sherman, Benedicta, and Golden Ridge. Approaching 
Maewahoe, it takes the form of two-sided reticulated ridges inclosing 
several kettleholes. The ridges here are higher and steeper than they are 
farther north, and are composed largely of pebbles, cobbles, and bowlder- 
ets. The Molunkus Stream empties into the Mattawamkeag River a short 
distance west of Kingman. For 12 miles north of its mouth the Molunkus - 
flows with a very sluggish current, and in time of flood overflows its broad 
alluvial plain of silty sand and clay. The reticulated ridges at Macwahoe 
were deposited at the foot of the steeper slope of the valley. From near 
the north line of Macwahoe to Kingman the gravel is found on the east 
side of the Molunkus and at a distance of from one-eighth to near one-half 
a mile from it. The lateral slopes of the valley are gently inclined toward 
' the west, and the gravel is seldom found more than 380 feet above the 
river. In respect to its material and stratification, this plain, situated on 
the side of the hills above the river, is exactly like the low plain of gravel 
which fills the bottom of the valley farther to the north and which has the 
external form of a plain of valley drift. But the plain or terrace on the 
side of the hill above the river is plainly of glacial origin, and this shows 
the origin of the plain in the bottom of the valley farther north. They 
differ in no respect except situation with respect to the river. 

South of Macwahoe the gravel becomes finer, and then comes an inter- 
esting study. For 2 miles north of Kingman we find a north-and-south 
line of ridges of fine sand. The large alluvial plain of the Molunkus lying 
to the west could have furnished sand which the west winds might drift up 
the hill. The question arises, Are these ridges and terraces of sand really 
the osar or are they blown sand? I have seen great numbers of sand dunes 
in various parts of the State, but never any north-and-south ridges showing 
such steep lateral slopes as these or forming a narrow and nearly continuous 
ridge for 2 or more miles. I therefore conclude that this sand is the osar. 
The ridge is well developed at the cemetery in the northwestern part of 


Kingman Village, where the railroad has cut through it to a depth of about 
MON XXXIV——7 


98 GLACIAL GRAVELS OF MAINE. 


15 feet. South of this point the glacial river crossed the valley of the Mat- 
tawamkeag River. No sand or gravel is visible in the valley for half a 
mile or more; such deposits may perhaps have been laid down and have 
been washed away by the river or covered out of sight by its alluvium. 

At Kingman there is an excellent opportunity to compare the shapes of 
the stones of the glacial gravels with those of ordinary stream gravels. The 
Mattawamkeag River at this place has cut down through a broad ridge or 
sheet of till to a depth of 30 or 40 feet, and has deposited the stones of the 
eroded till as a narrow plain of valley drift extending down the valley for 
about one-fourth of a mile. A series of rapids existed at this point before 
the building of the dam; and directly after the melting of the ice-sheet, 
when the fall must have been 30 or more feet higher than at present, the 
rapids and waterfalls must have formed quite a cataract. While the deep 
cut was being eroded the stones of the till must have been subjected to 
much more abrasion than is common except in case of the steeper mountain 
valleys, yet they preserve their till shapes very well. Their surfaces are 
polished, and the apices of the angles are more rounded than those found 
in the beds of the rivers and streams of Maine, except near the White Moun- 
tains and in the valleys followed by the glacial rivers. Their shapes are 
far nearer the angular and subangular shapes of the tillstones than those 
of the glacial gravel. As one sees how much more rounded the stones of 
the osars are than this stream gravel at a place favorable to attrition, he can 
not fail to be impressed with the great amount of attrition and frequent 
changes of position to which the stones of the osars owe their shapes. The 
alluvium of the Mattawamkeag River consists of fine sand and clay, except 
for short distances near the rapids and waterfalls. 

The dam at Kingman originally extended from a bank of solid till on 
the north to the terrace of rolled gravel, cobbles, bowlderets, and bowlders 
before described. Twice in time of high water this loose gravel on the 
south side of the river has been undermined and eroded by the water fall- 
ing over the dam until the water escaped around the south end of the dam. 
It thus happens that the dam is now twice as long as it was originally and 
the channel is much broader at the dam than it is a short distance below. 
At the time of my visit the water was flowing through three chutes near the 
bottom of the dam, situated at intervals of about 12 feet. Between these 
swift streams two ridges of coarse gravel had collected beneath the water. 


5 NT ele eam 


Peres 


SEBOOIS-KINGMAN-COLUMBIA SYSTEM. 99 


The ridges were thus flanked on each side by a stream. About 30 feet 
below the dam these two ridges were connected by a transverse ridge, thus 
inclosing a kettlehole about 10 feet deep. Here is well illustrated one of 
the ways in which reticulated kame ridges inclosing basins and depressions 
are deposited by glacial streams as they shoot swiftly out of their narrow 
channels or tunnels into a broader channel or into a lake or the sea. 

Not far south of the Mattawamkeag the osar begins again and con- 
tinues somewhat interruptedly through Webster to the Mattagordus Stream, 
in Prentiss. It then follows the valley of this stream for several miles south- 
ward, expanding into a series of reticulated ridges inclosing kettleholes 
The gravel here is very coarse, and cobbles, bowlderets, and bowlders 
abound. Near the northwest corner of Springfield the system turns south- 
west. It crosses the road from Springfield to Lee about midway between 
those villages, consisting at that point of a low plain of well-rounded gravel 
which incloses a small lake, the source of one branch of Mattakeunk Stream. 
Just north of the road is a broad dome or hummock of morainal aspect, 
since it is strewn with many bowlders 2 to 4 feet in diameter. Examina- 
tion of these bowlders on faces not weathered shows that they have been 
polished by water. These bowlders are granitic, like the far-traveled 
bowlders of the surrounding district, while the osar-plain near it is com- 
posed largely of slate and schists, like the local rock. The lower parts of 
the till of that region are mostly derived from local schists and calcareous 
and argillaceous slates. In the region east and northeast of Mount Chase 
and Patten numerous granite outcrops have contributed a great number of 
granite bowlders, and they are found covering the slaty till for many miles 
to the south. The granite bowlders in Springfield and Lee are unusually 
numerous, and there may possibly be an outcrop of granite somewhere to 
the south of the Mattawamkeag, but careful inquiry has failed to find it. 

The situation may be summed up as follows: The osar-plain at this 
point is composed chiefly of the same material as the lower part of the till, 
while the outlying hummock resembles in composition the upper till. The 
osar-plain shows few or no bowlders, while the hummock is largely com- 
posed of them. The base of the outlying ridge is but little higher than 
the osar-plain. Evidently the conditions under which these deposits were 
formed were different in the two cases. There are numerous swells and 
ridges of till near this place. During the final melting of the glacier the 


100 GLACIAL GRAVELS OF MAINE. 


ice might for a time continue to flow across the valley until checked by the 
hills of Springfield and Lee, and the remarkable mounds of till may par- 
take of the nature of a terminal moraine. The mound of glacial gravel 
lying near the osar-plain may date from this period. I could find no 
sions of a glacial stream, a lateral tributary of the main river, reaching 
farther north than this mound. The very large size of the bowlders of the 
mound indicates that it was formed subglacially and makes it probable that 
the deposit is partly or wholly a water-washed terminal moraine. The 
region deserves more careful study than I have been able to give it. 
Apparently the upper ice-bearing granite bowlders from the north contin- 
ued to flow over the lower ice after the latter was partially embayed. The 
osar-plain soon crosses a low divide at an elevation near 200 feet above 
Kingman, and then follows the valley of the Passadumkeag River to Nick- 
atous Stream, where it turns from its southwestward course to south. It 
here takes the form of a two-sided ridge 80 feet high (at an elevation above 
the sea of 380 feet, as determined by spirit level by D. F. Maxwell, C. E.), 
and continues as a prominent ridge for several miles southward. It then 
turns more nearly southeastward and follows the Narraguagus Valley for 
many miles, most of the way lying one-fourth of a mile or more to the 
west of the river. Part of the way it takes the form of a single two-sided 
ridge; at other places it is an osar-plam one-eighth of a mile or more in 
breadth, and occasionally it expands into narrow plains of reticulated ridges. 
North of Lead Mountain, in Beddington, an osar-ridge composed almost 
wholly of bowlderets and bowlders is found on the eastern border of the 
gravel, while to the west extends a plain of sand and gravel 1 to 3 miles 
wide. The western portion of these plains shows some low sand dunes. 
But for the wind, the plains would probably now be quite level on top. The 
material plainly becomes finer as we go westward. The plain was a delta 
deposited in a glacial lake or in the sea. Its elevation, by aneroid, is more 
than 300 feet above sea level. 

Just south of Lead Mountain there is another gravel plain of rounded 
shape, about three-fourths of a mile in diameter. It ends in a steep bank 
downward both on the west and south, beyond which is till, not a plain of 
clay. It is gently rolling on the top, yet shows finer sediments on the west 
and south, and must have been deposited in an open body of water. The 


OO ae 


SEBOOIS-KINGMAN-COLUMBIA SYSTEM. 101 


following considerations make it probable that both this plain and the one 
north of Lead Mountain were deposited in glacial lakes rather than in the 
sea: First, the contour of 240 feet lies several miles south of here, not 
more than 3 or 4 miles north of Deblois Village; second, no marine sands 
or clays are found in the valley of the Narraguagus far to the north of 
Deblois, whereas the basin of Beddington Lake ought certainly to be coy- 
ered with marine clay if the sea formerly extended north of Lead Mountain; 
third, the fact that the plain south of Lead Mountain ends in a rather steep 
bank on the west and south is most easily explained on the hypothesis that 
a glacial lake was there bordered by walls of ice. At Upper Beddington 
the osar-plain once filled the whole valley of the Narraguagus to a height 
of 50 feet and a breadth of about one-eighth of a mile, though the river has 
now deeply eroded the gravel along the axis of the valley. Going north- 
ward a short distance, we find the glacial gravel leaving the valley and 
keeping off to the west on ground 30 to 75 feet above the river. Above 
this point there is but little gravel of any kind in the bed of the Narra- 
guagus. The valley drift is scanty, and the stones it contains are plainly 
tillstones, which have lost but little of their till shapes, a great contrast to 
the very round stones of the osar-plain that fills the valley at Upper Bed- 
dington. Now, if at the time the delta-plain north of Lead Mountain was 
being deposited the sea occupied the valley of the Narraguagus as far north 
as that place, then no reason can be given why the glacial gravel should 
not spread across the open valley as it did at Upper Beddington, instead of 
being deposited so abundantly to the west of the river and on land consid- 
erably higher. These appearances are just as if, during the final melting 
of the ice, a tongue of ice or a local glacier continued to flow down the 
unobstructed north-and-south valley of the Narraguagus, while to the west, 
in the lee of hills that obstructed the ice flow, the ice had already melted, not 
being replenished from the north, like the glacier in the open valley. On 
this theory the ridge of bowlderets and bowlders lying on the east side of 
the plain north of Lead Mountain may in part be a water-washed lateral 
moraine of the hypothetical valley glacier. 

The gravels of this series appear on the shores and islands of Bedding- 
ton Lake and then expand into broad, rather level-topped plains that are 
continuous with the great Deblois-Columbia plains, which will be described 


102 GLACIAL GRAVELS OF MAINE. 


in connection with the Katahdin system. It has not been possible thus far 
to distinguish in these plains the gravels brought down by the respective 
glacial rivers. 

The amount of sediment transported by this long osar river is very 
great. The more noticeable features of this gravel system are the fol- 
lowing: For most of its course the gravel takes the form of a two-sided 
ridge (osar proper) with arched cross section. At intervals are found 
several reaches of a low, broad ridge or plain, rather flat on top in cross 
section, but in longitudinal section, both up and down, parallel with the 
surfaces passed over by the system. ‘The stratification of this plain is rather 
horizontal or slightly arched in cross section. To this plain-like enlarge- 
ment of the osar I have given the name broad osar, or osar-plain. In 
places this plain enters a valley, and it then for some miles fills the bottom 
of the valley from side to side, like a plain of valley drift, and is often 
eroded into terraces. The broad osar in such situations is readily distin- 
cuished from valley alluvium by the more rounded shape of the pebbles 
and by the fact that the plain soon leaves the valley and is found on the 
hillsides where no ordinary stream could have deposited it, the pebbles and 
all other features exactly resembling that portion of the plain found in the 
valley. On the north it originates about 700 feet above the sea, and it ends 
in Columbia but a few feet above high tide. Five times it leaves large 
valleys of natural drainage and crosses hills into other valleys, besides 
crossing many minor elevations. Its remarkable meanderings are in gen- 
eral determined by the relief forms of the land, since it does not cross hills 
more than about 200 feet high, measured on the north, but it does not always 
follow the lowest passes. Reaches of fine matter alternate with coarse, 


and where the coarsest matter appears the system generally takes the form 


of reticulated ridges inclosing basins. The most abundant deposits of 
large stones and bowlders are in the granitic region of the lower Narra- 
guagus Valley. North of Springfield there are only two places where the 
stones are very large: One in Prentiss, at the middle of a long slope of 15 
miles northward, and one at Macwahoe, near the middle of a southward 
slope of more than 20 miles. Intermediate between these two points (near 
Kingman, at the bottom of the deepest valley which the system crosses) 
the material is unusually fine, i.e., fine sand. The gaps in this gravel system 
are less numerous and shorter than in any other of the long systems. 


EEE a ee 


| ee 


a 


WINN-LEB GRAVELS. 103 


“Norway pine” plains —In western Maine a growth of the various yellow 
pines known locally as “Norway pine” is a proot of the presence of 
reticulated kame ridges. In eastern Maine such pines are often found on 
delta-plains of nearly horizontally stratified sand and gravel, some of which 
are special sediments deposited in the sea. The presence of a yellow-pine 
growth is indicative of water-washed matter, and that is about all that I am 
yet able to affirm of eastern Maine. 

Length of the Seboois-Kingman-Columbia system, about 125 miles. 


WINN-LEE GRAVELS. 


A line of glacial gravels extends nearly north and south along the 
valley of the west branch of the Mattakeunk Stream. It passes through 
the eastern part of Winn into Lee. Most of the way these gravels take the 
form of an osar-plain. At Lee Village this plain, which is there nearly 
one-fourth of a mile wide and rises 10 to 30 feet above the surrounding 
till, becomes somewhat reticulated and incloses a lakelet and trotting 
track. Southeast of Lee Village the gravels become somewhat discontin- 
uous, yet the gravel can readily be traced over the southwestern spur of a 
high hill and thence more nearly east along a low valley to join the main 
system not far from the Passadumkeag River, east of No. 3 Pond. It is 
uncertain whether this series has any northern connections. A well-defined 
osar extends from the Penobscot River for 3 or more miles northward along 
the valley of the Mattakeunk Stream. The glacial stream which deposited 
it probably flowed farther than this place. Its probable course was from 
the mouth of the Mattakeunk southeastward along the Penobscot Valley to 
Mattawamkeag, thence up the valley of the Mattawamkeag River to the 
Mattakeunk Stream, and thence along this valley to Lee. Yet it is some- 
what difficult to make out the connection with certainty. Mattawamkeag 
Village stands upon a terrace of well-rounded gravel at an elevation of 
about 190 feet. At the time the sea stood at 230 feet, the Penobscot Bay 
of that time would extend beyond Mattawamkeag up both the Penobscot 
and Mattawamkeag valleys. If a plain of glacial gravel were deposited 
in these valleys, the tidal currents would subsequently have modified and 
more or less reclassified the surface portion, and these marine sediments 
would afterwards have been more or less acted upon by the rivers after the 
sea receded. At Mattawamkeag we have to distinguish glacial, marine, 


104 GLACIAL GRAVELS OF MAINE. 


and fluviatile drift. The details are complex, and space does not permit a. 
full diseussion of the problem The most probable interpretation of the 
facts is that we have all three forms of drift represented in the Mattawam- 
keag terraces and that the glacial river followed the route above indicated. 

Length from Mattakeunk to No. 3 Pond, about 15 miles. 

Several narrow terraces of water-washed gravel are found at intervals 
in the valley of the Penobscot in Winn and Lincoln. They are found at 
least 50 feet above the Penobscot River, and are probably sea beaches. 


KATAHDIN SYSTEM. 


This is an extensive osar system, deposited by a very large glacial 
river which drained the region about Mount Katahdin and which was 
remarkable for the number of its tributary branches. It is uncertain which 
is the longest tributary of this rather inaccessible system. 

A horseback, or two-sided ridge, passes the Seboois farm, near the west 
branch of the Seboois River in T. 6, R. 7, Penobscot County. It is known 
to extend 3 miles northward into the forest. It passes only a few rods. 
from the farmhouse and has been cut through at this point by a road to 
the depth of 12 feet. The stones are so angular that at first sight the ridge 
appears to be a meandering lateral moraine. A more careful examination 
shows that the finer detritus has been washed out of the mass and that the 


stones have been slightly water polished. It is thus proved to be a form of 


glacial gravel, the residue left after the till had been washed by gentle cur- 
rents. The osar can be traced for several miles southward nearly parallel 
with the west branch of the Seboois River, but it disappears near where 
this stream enters the remarkable canyon by which the Seboois penetrates 
the Katahdin highlands. This gorge extends from near the junction of the 
two branches of the Seboois River almost to the junction of this river with 


the East Branch of the Penobscot. For several miles at the north end of 


this wild gorge the rocky hills slope steeply down to the river, and there is 
a coustant succession of rapids; naturally there is but little water drift in 
this part of the valley. Southward the valley widens here and there and 
contains a plain of sand, gravel, cobbles, and bowlderets. In places the plain 
is about one-fourth of a mile wide and rides 30 or 40 feet above the present. 
bed of the river. From one to three terraces of erosion border the river. 
The stones have been much more water rounded than those found in the 


—— 


U. S. GEOLOGICAL SURVEY MONOGRAPH XXXIV PL. Hil 


A. LAKELET SURROUNDED BY GLACIAL GRAVEL; LEE, 


B. DOME OF COARSE GRAVEL; SPRINGFIELD, 


KATAHDIN SYSTEM. 105: 


beds of the present streams of that part of the State, and are more rounded 
than those found in the midst of the rapids of this stream to the north of 
the plains in question. The valley is not valley drift, but is an osar-plain. 
The hills bordering the canyon on each side are from 400 to 1,000 feet. 
high. It is certain that a glacial river flowed into the north end of the 
gorge, and the height of the lateral hills is such that it could not escape 
except along the valley. The Seboois Valley broadens for several miles. 
north of its junction with the East Branch of the Penobscot. 'This wide 
valley is bordered by plains of clay, sand, and gravel, and so also is the 
valley of the East Branch of the Penobscot from this point to Medway. 
Whether any part of this is an osar-plain I can not now be certain. At the 
time of my exploration in 1879 I had not diagnosed the level-topped 
osar-plains, and regarded them as valley drift. The sedimentary plain of 
these valleys is from near half a mile to a mile or more in breadth. My 
notes refer to certain coarser gravels on one side of the plain, which perhaps. 
are a broad osar. A well-defined osar begins about 14 miles north of Med- 
way and extends continuously southward to that place. While passing 
along the river in a canoe I saw no osar ridges farther north from Medway 
than this. This ridge is bordered on the east by the river and then by a 
broad sedimentary plain extending for many miles southward. It is com- 
posed of clay overlain by sand and gravel, all very nearly horizontally 
stratified. The ridge has steep lateral slopes on both east and west sides. 
It is usually densely covered by vegetation and from the river does not 
appear very different from the steep bluff of erosion in the alluvium on the 
east bank of the river. None of the geologists who passed up this valley 
appear to have noticed the ridge, but Thoreau must have seen it and recog- 
nized its nature. He writes (Maine Woods, p. 294): ‘““We stopped early 
and dined on the east side of an expansion of the river [Hast Branch of the 
Penobscot] just above what are probably called Whetstone Falls, about a. 
dozen miles below Hunt’s. * * * There were singular long ridges here- 
abouts, called horsebacks, covered with ferns.” 

In a few places the osar expands into oval or elongated plains, not very 
broad, but rather flat on top, sometimes inclosing kettleholes. 

A comparison of the alluvial drift of the valleys of the East Branch of 
the Penobscot and Seboois River above Medway with that of the valleys of 
Pleasant River, the Piscataquis, the upper Kennebec, the Carrabassett, and. 


106 GLACIAL GRAVELS OF MAINE. 


the Sandy, shows that the sedimentary deposits are very nearly the same 
in all of them. These valleys are all at about the same distance from the 
sea and the sediments may well be interpreted by comparison. In some 
of these valleys, as the Pleasant and Carrabassett, the sediments are plainly 
overwash or frontal plains, composed of matter that was brought down by 
glacial streams to the extremity of the ice and then spread out over the 
bottoms of the open valleys. They mark a stage in the retreat of the ice 
when it still lingered in the upper parts of these valleys and practically 
formed local valley glaciers. Since a true osar river flowed from the north 
into the gorge of the Seboois River and also in the lower part of the valley 
of the East Branch, the history of these valleys is probably this: A long 
osar river at one time flowed through the valleys. Later the osar expanded 
to an osar-plain in the gorge of the Seboois and for some miles down the 
East Branch. Finally, on the retreat of the ice the lower portion of these 
valleys was covered by a frontal plain of sediments derived from the glacial 
streams of the glacier that still lingered near the head waters of the Seboois 
Valley. 

At Medway this osar crosses the West Branch of the Penobscot, and, 
except an island in the river, has been washed away by it. The osar then 
follows the south bank of the river for about 3 miles, being washed away in 
some places. Just west of the mouth of Pattagumpus Stream there is, on the 
south side of the river, a plain of high reticulated ridges, forming a jumble of 
hummocks and hollows. The gravel here is coarser than the average of the 
ridge. The osar for 3 miles has been taking a nearly east course, and directly 
before it lay the broad Penobscot Valley. The osar river, leaving this 
valley of natural drainage, turned to the right through a deflection angle 
of nearly 185° and took a southwest course up the Pattagumpus Valley, 
then over a low divide and down a branch of Maddunkeunk Stream into 
Chester. Near the Penobscot River it turns southwestward and follows the 
west side of that river for several miles, and then at the north end of 
Hocamoc Island it crosses to the east side (PI. IV, 4). The north end of 
this island is composed in part of the osar gravel. South of this point the 
gravel takes the form of a series of massive ridges or plains, separated by 
short gaps. These ridges are 20 to 50 feet high, and are rather level on the 
top, in places gently rolling and containing shallow hollows. ‘The system 


U. S. GEOLOGICAL SURVEY MONOGRAPH XXXIV PL. IV 


A, OSAR CROSSING PENOBSCOT RIVER; HOCAMOC ISLAND, LINCOLN, LOOKING NORTH. 


The bluff at the left center and the plain at the right are composed of glacial gravel. The osar here forms a broad and massive table. 


B. OSAR EXPANDED TO A PLAIN; SOUTH LINCOLN. LOOKING NORTHWEST. 


The hill at the right, on-which are the house and the trees, is the extension of the level-topped ridge at the left. The gravel mesa here shows the 
steep lateral slopes characteristic of sediments deposited between ice walls. 


KATAHDIN SYSTEM. 107 


passes a short distance east of South Lincoln, and soon takes the form of a 
single two-sided ridge, which takes a southeastward course and crosses the 
Maine Central Railroad a short distance north of Enfield station (PL V, B). 
North of Lincoln the osar is chiefly composed of small fragments of slate, 
but in. Enfield it passes through a granitic area and contains many 
bowlderets and bowlders of granite, up to 25 feet in diameter. 1 formerly 
regarded the numerous bowlders on the surface as having been dropped by 
ice floes. The proof is abundant that ice floes often did this, but recent 
excavations in the osar in the northern part of Enfield show that water- 
polished bowlders are scattered through the gravel to the depth of at least 8 
feet. The latter are, therefore, a true part of the osar, though there are 
some bowlders on the surface that are not water-polished on what seem to 
be unweathered faces, and these may be floe bowlders. The ridge here is 
30 to 50 feet high and of arched cross section. The osar passes a short 
distance east of Enfield station and then traverses a great clay-covered 
plain in the towns of Passadumkeag, Greenbush, and Greenfield. Much of 
this plain is as level as the prairies of the West, and formed part of the 
expanded Penobscot Bay. The flanks of the osar are here covered, often 
deeply, with clays containing clams and other marine fossils. Both the 
clay and the osar are sprinkled with occasional bowlders having the shapes 
of till bowlders. There is nothing lke a sheet of till overlying the clay, 
and the bowlders indicate the work of ice floes rather than a readvance of 
the glacier after the deposition of the clay. It is noticeable that more 
bowlders were stranded on the hillsides than on the lowlands, and they are 
most numerous on the north sides of hills, where the ice floes drifted as they 
made their way down the bay. The Penobscot Bay at the time the sea 
stood at 230 feet was 15 or more miles wide from east to west at this point. 
In one place near the north line of Greenbush so many bowlders were piled 
on the top of the osar that no attempt has been made to plow the surface. 
A road is made on the top of the osar for many miles, the ridge forming a 
natural roadway through the level and sometimes swampy region. The 
osar here seldom rises more than 20 or 30 feet above the plain of marine 
clay, but in three places in Greenbush it expands into a series of broad and 
plain-like ridges, inclosmg some kettleholes. The ridges here rise above 
the level plain to a height of 100 feet. Rising so abruptly out of the plain, 


108 GLACIAL GRAVELS OF MAINE. 


they are very prominent landmarks from every direction, and are locall 
’ Vi 


known as “ 


mountains.” Their material is rather coarser than the average: 
of the osar, and shows the usual sprinkling of stranded bowlders. 

In Greenfield this osar unites with the Howland tributary. Near their 
junction are extensive sand-and-gravel plains having a gently rolling surface. 
I once supposed that the sea had washed down the original ridges as depos- 
ited by glacial streams and had redeposited them with a nearly horizontal 
stratification. As shown elsewhere, the power of the sea to erode till and 
glacial gravel was very limited except on the most exposed coasts. These 
plains in Greenfield were deltas deposited by the glacial waters near where 
they poured into the sea, or possibly into a large glacial lake. 

The gravel plain continues on southward along a branch of the Sunk- 
haze Stream. Soon the plains are left behind and we find an osar of ordi- 
nary type, often of very large size. This is a treacherous wilderness, and 
the explorer must not let the osar get out of his sight if he can help it. 
Just as he approaches the head of the Sunk-haze, he reaches a particularly 
ageravating swamp. With many misgivings, he concludes to trust the osar 
for just a few minutes and flank the swamp. Arrived at the other side of 
the swamp, it is just as he had a right to expect. The osar has vanished. 
Before him is the top of the divide, dreary with bare ledges and an endless 
array of roches moutonnées sprinkled with large bowlders. But really we 
are dealing with rivers, and the gravel is only a symbol. A mighty osar 
river certainly came from the north to this place. What became of it? It 
~ must have swept over that divide with velocity sufficient to enable it to carry 
all loose matter before it except the large bowlders. Still we must seek 
field evidence that it passed over this divide. Going east, we soon descend 
to the Morrison Pond, a long narrow body of water situated between two 
high granite hills which slope steeply down to the pond from each side. 
Within a half mile the osar reappears. Round cobbles and bowlderets. 
soon appear, and in the jaws of the pass take the form of a large windrow 
of polished bowlderets and bowlders situated on the south side of the pond. 
Then for a mile or two on a steep down slope there is but little sediment to 
represent the osar. The osar river crossed the west branch of the Union 
River, and immediately we find a broad series of sand and gravel plains 
in Aurora known as the Silsby Plains. These are about 5 miles long and 
from 1 to 3 miles wide. They extend about 1 mile north of the outlet of 


U. S. GEOLOGICAL SURVEY MONOGRAPH XXXIV PL. V 


A. OSAR FORKING INTO A DOUBLE RIDGE. 


B. KATAHDIN OSAR, ENFIELD, LOOKING NORTH. 


The bowlders on and within the ridge are of granite with waterwoin surfaces where unweathered. This view shows the characteristic development 
of an osar within an area of granitic rock. 


KATAHDIN SYSTEM. 109 


Morrison Pond. This broad plain consists of nearly horizontally stratified 
sand and gravel, the material becoming finer as we go away from the mouth 
of the outlet of Morrison Pond. This proves that it is a delta deposited 
in some body of water. These plains are about 120 feet above the sea, and 
at the south the sand passes into marine clay, which covers the valley of 
Union River from this point all the way to the coast. It is therefore evident 
that the great Katahdin glacial river here emptied into an arm of the sea 
which extended up the valley of Union River to a point several miles above 
these plains. But the history does not here come to an end. From near 
the Morrison Pond outlet a ridge or series of ridges of coarse gravel, cob- 
bles, and even bowlderets, extends southeastward across the Silsby Plains. 
‘These ridges rise above the surrounding plain. They are of arched cross 
section and are clearly of different origin from the plain of nearly horizon- 
tally stratified gravel and sand which surrounds them. Near the Union 
River, on the west side of the plain, this ridge of coarse matter is inter- 
ssected by several lower transverse ridges which are parallel with the trend 
of the valley, and it is also deeply cut through by furrows having the same 
direction. Apparently the swift tidal currents as they swept up and down 
the valley cut furrows through the ridge, which crossed the valley obliquely, 
and built up the matter as transverse ridges. . 
The facts, so far as known, indicate that the history of this interesting 
locality is as follows: While the ice was still deep, the glacial river flowed 
through the Morrison Pond Pass and so on obliquely across the level val- 
ley of the west branch of Union River, where the Silsby Plains now are, 
and deposited the ridge of coarse matter. But during the final melting of 
the ice the sea advanced, and finally covered all the valley to a depth 
of about 100 feet. But the ice to the north in the Penobscot Valley was 
not yet melted, and the glacial river continued for a time to pour its freight 
of sediment into the bay, and the tide carried the finer matter far and near 
in nearly horizontal stratification. The delta thus formed extended about 1 
mile north of the mouth of the glacial river and 4 miles south and south- 
east. While this was going on, the tides, sweeping up and down the val- 
ley, partially washed away the ridge which had been laid down before the 
melting of the ice, cut transverse channels through it, and reclassified the 
matter. According to this hypothesis, the Silsby Plains consist of an older 
osar which was deposited between the ice walls and afterwards bordered 


110 GLACIAL GRAVELS OF MAINE. 


and overlain by a delta-plain deposited by the glacial waters in an open 
arm of the sea. 

_ A series of high granite hills borders the valley of the west branch of 
Union River on the east, and the osar, having crossed the Silsby Plains, 
ends right in front of a very low and level pass between two of the hills. 
For near a mile in this pass no glacial gravel could be found, but at the 
east end of the pass the gravel begins again as an osar-plain one-eighth of 
a mile or more wide. The system is soon cut through by the middle 
branch of Union River and then takes the osar form of a two-sided ridge 
(PI. V, A). This ridge rapidly enlarges toward the southeast and becomes 
known as the Whalesback. It is one of the largest ridges of glacial gravel 
in Maine, varying in height from 50 to 100 feet above the plain of marine 
clay which deeply covers its base. For several miles a parallel smaller 
ridge lies a short distance west of the main ridge, and the two are con- 
nected by numerous cross ridges. Thus are inclosed numerous large kettle- 
holes and swamps containing several acres. Among the local legends, I 
find one to the effect that Agassiz was greatly interested in this huge ridge, 
speaking of it to my informant as a moraine. The Air Line road from 
Calais to Bangor is made on the top of this ridge for about 3 miles. The 
ridge becomes lower toward the south, and the Whalesback is considered 
to end at this low place, near where the Air Line road leaves it and turns 
east.. The gravel does not end here, however, but continues on southeast- 
ward along the valley of Leighton Brook, a tributary of the middle branch 
of Union River flowing northwest, most of the way as a prominent 
two-sided ridge. In the eastern part of T. 21 it escapes from the hilly 
country into the great plain of the Narraguagus, which extends for many 
miles to the sea. It at once expands into a series of low and broad reticu- 
lated ridges, showing a gentle rollmg and hummocky surface. Soon the 
gravels become more level and horizontally stratified. They extend almost 
continuously through Ts. 22, 16, and Deblois, into Columbia. Here and 
there, rising above the horizontally stratified sediments, are ridges of 
arched cross section that were evidently deposited within the ice walls. 
Most of these plains from Rocky Pond and southeastward must be con- 
sidered as a marine delta. From Columbia to Deblois, and perhaps still 
farther northwest, the southern edge of the gravel plain ends in a steep 
bluff and shows so many cobbles and bowlderets that it seems quite certain 


KATAHDIN SYSTEM. 111 


that the plains were bordered by ice at the time they were being deposited. 
Not far west of Deblois the plain ends on the south in sand, which passes 
by degrees into clay, and there are several areas of sedimentary clay on 
the north side of the sand plain, and partly inclosed by it. A minute 
examination may show that some of them were laid down in glacial lakes. 
In the absence of direct proof to the contrary, I provisionally assign to them 
all marine origin. Accoruig to my present information, the most prob- 
able interpretation of the facts is this: The plains southeast of Deblois 
were deltas deposited within ice walls, i. e, in a broad channel or fiord 
inclosed by ice at the sides, but open to the ocean in front. Subsequently, 
when the ice had all melted over the lower part of the Narraguagus Valley, 
the Katahdin giacial river flowed into the open sea not far from Rocky 
Pond in T. 22, and at this time were formed the large delta-plains situated 
west and northwest of Deblois. The situation is further complicated by the 
fact that the great Seboois-Kingman osar river was at the same time form- 
ing a marine delta in the Narraguagus Valley north and northeast of Deblois. 

The eastern end of the United States Coast Survey base line is situ- 
ated just at the top of the bluff which borders the Deblois-Columbia Plains 
on the south. Toward the east the plain becomes narrower and the mate- 
rial coarser. Near Epping Corner, in Columbia, the gravel forms a plain 
near one-half mile wide, rising from 40 to more than 100 feet above the 
marine clays which border it on the north, east, and south. The plains. 
extending from here northwestward toward Deblois are widely known in 
all this part of the State as the Epping Plains. Near Epping the plain is 
rolling and ridged on the top and contains numbers of shallow kettleholes. 
From it proceed several tongues. On the north three of these tongues pro- 
ject out one-fourth of a mile or more toward the Pleasant River. he val- 
ley of this river is here a broad and very level clay plain, and the ridges 
rising steeply 100 feet or more above the plain form a very prominent line 
of bluffs. An examination of the map shows that the Seboois-Kingman 
and the Katahdin osar rivers together drained near one-fifth of the southern 
slope of Maine, and that all this vast rush of glacial waters converged at 
Epping—a sufficient cause for the great plains of Columbia, Deblois, and 
the Narraguagus Valley. 

A tongue of glacial gravel extends from Epping Church southward on 
the road to Addison. This soon becomes discontinuous and the gravel 


112 GLACIAL GRAVELS OF MAINE. 


‘hummocks grow smaller, and the series ends within about 2 miles. To the 
‘south of this point lies a low clay plain all the way to the sea in Addison. 
In this I could find no glacial gravel rismg above the clay. The only east- 
ward or southward connections of the Epping Plains which I have been 
able to find are certain broad plains which extend through Columbia Falls 
eastward toward Masons Bay, Jonesboro. In the midst of the Deblois- 
‘Columbia Plains are several areas of till rising above the gravel plains. 

Near Epping Church, Columbia, is an excavation showing an interest- 
ing section. On the top is a thin layer of well-rounded, medium-sized 
gravel. Beneath this is a stratum 2 to 4 feet thick containing unpol- 
ished stones and bowlders having the shapes of tillstones. This plain, 
being below the contour of 230 feet, would project from the west far out 
into the expanded bay of that time occupying the valley of Pleasant River, 
and would be much exposed to stranding ice: floes. I do not see how in 
general the scattered and isolated bowlders having till shapes found upon 
and in the marine clays can have been brought to their present positions 
except by ice floes or small bergs. But this till-like stratum is so continuous 
that 1 see no objection, so far as the mass itself is concerned, to considering 
it a sheet of till. The till-like mass is found on the eastern end of the 
high plain, and does not extend far west of Epping Corner. This is where 
the ice floes would be most liable to run aground, and it is a point in favor 
of the ice-floe theory. I saw no bowlders distinctly glaciated, but this is 
not fatal to the theory of a readvance of the ice after the deposition of the 
plain of gravel. On either theory the surf would subsequently beat on top 
of the plain and wash down some of the highest gravel onto the adjacent 
till-like mass, though in many places there is no overlying beach gravel. 
As one goes over much of the plain near Epping the angular or unpolished 
bowlders make it look so much like a field covered by ordinary till that it 
needed the testimony of those who have fruitlessly dug wells to a great 
depth to convince me that the plain is underlain by 100 feet of coarse 
glacial gravel. A more careful exploration of the whole region is needed 
in order to decide the question of the origin of the till-like stratum. At 
present I incline to favor the ice-floe theory. 

Comparing the gravel of the Katahdin osar with the till, also with the 
country rock of the regions through which it passes, we find that both the 
‘till and the osar are made up chiefly of fragments of local rocks or of rocks 


U. S. GEOLOGICAL SURVEY MONOGRAPH XXXIV PL. VI 


Sak SAS 


SS 
San’, wi 


a We 
ee 


fg? = Lae 


A. BROAD PLAINS, EXTENDING FROM COLUMBIA FALLS TO JONESBORO, LOOKING EAST. 


The hill in center is a mesa or massive plain of glacial grave! 100 feet high. The foreground is covered with marine sediments. 


B PLAIN OF GLACIAL GRAVEL CONTAINING TILL-SHAPED BOWLDERS; NEAR EPPING CHURCH, COLUMBIA 


KATAHDIN SYSTEM. 113 


found not far to the north. , Yet there has plainly been a transportation 
southward along the line of the osar greater than the distance traveled by 
the till. Thus, north of Enfield the osar consists chiefly of slate. It there 
crosses a small granite area. The granite immediately appears in the ridge, 
and continues to be largely represented in it for 10 or 15 miles after reenter- 
ing the slate region, more abundant apparently than in the till over the 
slate area. Near Morrison Pond the osar again leaves the slate area and 
enters the great granite area extending northeast from Orland on the 
Penobscot Bay nearly all the way to Bay Chaleur. For several miles after 
entering the granite the osar contains more slate than the till. As a rough 
estimate, I compute that the stones of the osar traveled from 5 to 10 miles 
farther than those of the till. ; 

For most of its course the Katahdin osar is closely guarded by the 
wilderness. Whoever loves the large, generous works of nature, unspoiled 
by the hand of man, will find much to his taste in following this osar. A 
casual crossing of the system is insufficient for adequate appreciation. One 
needs to follow it for 100 miles or more in order to see what a grand geo- 
logical construction it is. As the mighty rampart stretches away before 
him day after day, the explorer becomes intensely interested in watching 
its varying developments. Railway embankments become insignificant in 
comparison with it. It is perhaps most beautiful in the midst of the dark, 
silent wilderness, gray with lichens. Its vegetation is interesting all the 
way from Thoreau’s horseback, covered with ferns; past days and days of 
white birch and poplar growth; past the hemlock thickets of the high pin- 
nacles or so-called “mountains” of Greenbush, where Linnzea and Chiogenes 
vie with pipsissewa and Epigzea in decorating the huge piles of gravel; past 
the checkerberry plains and mosses of Greenfield and the kame-inclosed 
sphagnous swamps of the Sunk-haze wilderness, lovely with calopogon, 
‘Pogonia, and Arethusa; and the interest keeps up even to the great blue- 
berry plains of Deblois and Columbia, and to the drosera-shining spruce 
swamps which cover the unsightliess of the cobbles, bowlderets, and 
rounded bowlders of the great plains near Rocky Pond. 

Not less interesting are its topographical relations. By the time one 
has seen the osar crossing transversely the Penobscot River twice and the 
valleys of three streams to their source, then crossing divides and descend- 


ing the valleys of the same number of streams flowing in the opposite 
MON XXXII vV——8& 


114 GLACIAL GRAVELS OF MAINE. 


direction, and in so doing taking its way in all directions from southwest 
around to south, southeast, and even east, by this time one will- see how 
irresistible is the proof that such a river must have been confined between 
ice walls to flow so independently of the surface forms of the land. Yet 
it did not flow wholly independently of them. It nowhere crosses hills 
more than 200 feet higher than the ground to the north of them, and thus 
it penetrates the high ranges only along low passes. Traveling southward, 
for two days before reaching the Morrison Pond Pass I had observed that 
remarkable gap through them, and at a venture assigned it as the gateway 
of the osar river. For a day and a half after the idea came to me the osar 
continued a nearly south course, and it often seemed impossible it could 
go so far to the east. But at last in the Sunk-haze wilderness it described 
a long and regular curve to the left and shot straight for its natural outlet 
between the hills. 

This osar affords interesting points as to the retreat of the ice north- 
ward before the advancing sea. To say nothing of the delta-plains depos- 
ited in reentering bays or broad channels within the ice up which the sea 
extended, we have at least two and perhaps three series of delta-plains 
deposited in the open sea. First, the ice over the Narraguagus Valley 
melted, so that the delta-plains west and northwest of Deblois were formed. 
Subsequently the ice disappeared over the valley of Union River, which 
then became covered by the sea. This arrested the further flow of the 
glacial river southeastward. For a time it continued to flow into the bay 
of the Union River Valley, and the Silsby Plains in Aurora were thus 
deposited. Still later, the ice receded up the valley of the Penobscot until 
the osar river probably poured into the broad Penobscot Bay of that period 
in Greenfield. The broad, plain-like ridges near the Penobscot River at 
South Lincoln, though deposited between ice walls, may have been in part 
due to the checking of the glacial water at that pomt by the advance of the 
sea. The same thing may have happened at the mouth of the Pattagum- 
pus, and the apparent plains of valley drift near the junction of the Seboois 
and the East Branch of the Penobscot may be either fluviatile or estuarine 
drift, brought down from above by glacial streams while the country to the 
north was still covered by ice. The pinnacles of Greenbush and several 
other enlargements of the gravel deposits were probably deposited in glacial 


KATAHDIN SYSTEM. 115 


lakes or in a plexus of sediment-clogged ice channels which were practically 
equivalent. 
Length, about 125 miles. 


STACHYVILLE-MEDWAY BRANCH. 


A nearly continuous ridge begins in the southern part of Staceyville 
and traverses a very level region for about 15 miles, when it approaches 
the Salmon Stream. Its course then lies along the west side of that stream 
for several miles, and not far north of the Penobscot River it expands into 
plains of sand and gravel, which are rather level on the top, so much so as 
to make it probable that they are a delta deposit, either in a glacial lake 
which then extended across the Penobscot Valley and for a short distance 
up the valley of the Pattagumpus Stream, in an estuary, or in the sea. 
The sea certainly extended for several miles up the Penobscot above Mat- 
tawamkeag, but how far I am as yet unable to determine. 

Length, about 20 miles. Much information as to the region about 
Medway has been received from Col. J. F. Twitchell. 


SALMON STREAM BRANCH. 


This has been traced northward along the valley of Salmon Stream to 
Salmon Stream Lake. It joins the Staceyville branch about 2 miles north 
of the Penobscot River. 

Length, about 10 miles. 


SAM AYERS STREAM BRANCH. 


This osar is said to extend as a two-sided ridge 6 or more miles along 
Sam Ayers Stream, above its junction with the Mattamiscontis Stream. 
The connections of this series are uncertain. The Champlain sea extended 
up the valley of the Mattamiscontis for several miles above South Lincoln, 
and if this short glacial stream emptied into the sea at some place in that 
valley, the series would end at that point ina marine delta. If so, this may 
be an independent system. But I found several domes of glacial gravel in 
that valley of the Mattamiscontis nearly opposite South Lincoln. These 
may be either an extension of the Sam Ayers Stream series or simply out- 
lying ridges of the main Katahdin system, which lies less than a half mile 
away across the Penobscot. My own exploration did not extend far up 


116 GLACIAL GRAVELS OF MAINE. 


the Mattamiscontis Valley. I provisionally include this short osar among 
the tributary branches of the Katahdin system. 


MILINOKET LAKE-HOWLAND BRANCH. : 


This, perhaps, ought to be considered as the main branch of the 
Katahdin system. 

A series of gravel ridges is reported by J. W. Sewall, C. E., of Old- 
town, as beginning near the West Branch of the Penobscot River at the 
mouth of Katahdin Stream and extending eastward along the valley of 
Aybol Stream for several miles. My information is conflicting and rather 
indefinite as to the region from the head of Aybol Stream eastward to Mili- 
noket Lake. On a down slope the glacial stream must have continued its 
flow through that region, but if it left any gravels in its channel they seem 
to have been scanty and discontinuous, just as happens on most steep down 
slopes in the State, and not to have attracted the attention of my informants. 
South of Milinoket Lake a nearly continuous osar extends along the valley 
of Milinoket Stream to the West Branch of the Penobscot River, at the 
east end of the enlargement of the river known as Shad Pond. At this 
point the ridge contains numerous highly rounded pebbles and cobbles, 
showing that it must extend for a long distance northward. It is not a large 
ridge, and numerous hummocks rise above the rest of the low ridge. The 
course of the osar lies obliquely across Shad Pond for about a mile, as is 
proved by islands of gravel rising above the water. It soon leaves the 
valley of the Penobscot and follows the Nollesemic Stream past the lake of 
that name, and then, penetrating a low pass, it extends southward near the 
Seboois River for many miles. The ridge is well developed almost all the 
way. Near the Piscataquis River it does not show above the marine sedi- 
ments and valley drift, and it has been either washed away or covered out 
of sight by the clays, or the gravel may never have been deposited in this 
part of the channel of the glacial river. his glacial river certainly crossed 
the Piscataquis Valley, for the gravel ridge begins again a short distance 
south of that river and continues southward through Edinburg and Argyle 
as a low ridge rising only 10 to 30 feet above the marine clays. It then 
turns southeastward, crosses the Penobscot River at Olamon Island, and 
soon spreads out into broad, rather level, plains as it approaches Greenfield. 

This glacial stream is pretty long, but, judging from the amount of sedi- 


SYSTEMS OF GLACIAL GRAVELS. 117 


ment it deposited, it was probably not so large as the Seboois-Medway- 
Enfield branch. It drained the region directly south of Mount Katahdin, 
and it is an open question whether it ought not to be known as the Katah- 
din osar. It is even more inaccessible than the Enfield branch. 

Length, 50 or more miles from Greenbush northward. 


SOPER BROOK GRAVELS. 


A ridge, probably of glacial gravel, is found along Soper Brook, north 
of Ripogenus Lake, in T. 4, R. 11, Piscataquis County. It is about 2 miles 
long, and is possibly a branch of the Katahdin system. 


NOTE ON THE UPPER PENOBSCOT VALLEY. 


I have not had opportunity to explore this valley above the Twin 
Lakes. On comparing the map of the upper Penobscot region with the 
country lying east and west of it, symmetry is seen to demand that the 
glacial gravels should extend farther north and west than is shown on 
the map. Probably the osars are there, but have not been discovered and 
reported. The hilly region about Katahdin can not be judged by the anal- 
ogy of the level areas, but to the west a more level country is found, 
where glacial gravels may be expected. 


EASTBROOK-SULLIVAN SYSTEM. 


This rather short system extends from the south end of Webbs Pond, 
Eastbrook, southeastward through Franklin and Sullivan. It traverses a 
rolling plain along valleys or over low hills, and lies wholly within the area 
that was beneath the sea. It crosses the Shore or Telegraph road, and then 
continues southward as a high, broad ridge of coarse gravel, cobbles, and 
bowlderets. At the east end of Hog Bay it turns abruptly eastward and 
goes up a narrow valley. It is said to continue for several miles in this 
direction and to end near Flanders Pond, in the northeast part of Sullivan. 


MINOR GRAVEL SERIES. 


These were probably deposited by different glacial streams. 

Amherst delta— A small, rather level-topped plain of sand and gravel is found 
on the Air Line road, about 3 miles west of Amherst Post-Office, at the south- 
ern base of a high range of granitic hills. Going south of the road the 
sediments become finer. The gravel passes by degrees into sand, and this 


118 GLACIAL GRAVELS OF MAINE. 


into clay, within one-fourth of a mile. This clay is continuous with that 
which extends down the valley of Union River to the sea, and is of marine 
origin, as shown by fossils found about 1 mile east of this place. North of 
the road we find two tributary branches. One ridge extends for about one- 
eighth of a mile northwestward, up the valley of a small stream; the other 
starts from a point a few rods east of this ridge and ascends another valley 
northward for one-half mile or more. This gravel plain is small, but inter- 
esting. The horizontal transition from gravel and cobbles on the north to 
sand: and finally clay on the south is shown with unusual regularity and 
within a short distance. It is an instructive instance of a delta deposited 
by two small glacial streams, whose mouths were so near each other that 
they formed a single delta-plain. 


NORTH MARIAVILLE SYSTEM. 


This is a discontinuous series of short ridges and hummocks separated 
by numerous short gaps, or apparent gaps. On the north the series begins 
about 1 mile north of North Mariaville and takes a south course along the 
west side of Union River for several miles. Near the road from Otis to 
Waltham it crosses to the east side of the river, where the gravel takes the 
form of a low terrace, while no corresponding terrace is found on the west 
side of the river and no similar gravel is in the bed of the stream. This is 
thus proved to be glacial gravel and not valley drift. South of this point 
the valley of Union River is a very level, clay-covered plain, and no ridges 
can be seen rising above the clay. Probably the series ends near this place. 


WEST MARIAVILLE MASSIVE. 


About 1 mile from Union River, on the road from North Mariaville 
southwestward to Tilden Post-Office, is a flattish-topped plain of well- 
rounded glacial gravel and cobbles. It is about one-fourth of a mile wide 
from east to west and three-fourths of a mile long. The plain becomes 
somewhat finer in composition toward the south, but the change is not so 
marked as it is in the case of most fan-shaped deltas. The plain is but little, 
if any, broader toward the south. It must have been deposited either in a 
glacial lake or within a bay of the sea bordered by ice walls that prevented 
the sediment from spreading. If so, the outlet channel toward the sea was 
probably narrow. 


CLIFTON-LAMOINE SYSTEM. 119 


PEAKED MOUNTAIN ESKERS. 


A series of ridges somewhat like an interrupted osar extends along the 
valley of a small stream that flows northward past the western base of 
Peaked Mountain, in the eastern part of Clifton. The series seems to end 
in front of a rather low pass leading southeastward through the high 
granitic hills. According to general analogy, this small stream must have 
flowed southeast through the pass, although it has not deposited much, if 
any, gravel on the steep slopes. It is possible that its course lay past Hop- 
kins Pond to the plain in the western part of Mariaville, above described. 
I have not explored the indicated route, which is quite inaccessible. 


CLIFTON-LAMOINE SYSTEM. 


This series appears to begin as an osar ridge about one-fourth of a mile 
northwest of Clifton Post-Office. From thence it extends for about 1 mile 
southeastward, when it turns nearly east and crosses the granite hills by a 
pass about 80 feet above Clifton (PI. VI, 4). This is the lowest place in the 
granite range to be found in this vicinity. The gravel is scanty at the top 
of the pass, but on the down slope soon becomes very abundant and expands 
into a series of two or more large ridges inclosing kettleholes. It soon turns 
nearly south along the valley of a brook past Floods and Spectacle ponds, and 
then in Otis spreads out into broad plains from 1 to 1$ miles wide. These 
extend several miles southeastward into the northern part of Mariaville. 
These plains are rather level on the top, and the sediment passes from 
coarse gravel and cobbles on the north to horizontally stratified sand on the 
south, which in turn ends in the marine clays. This proves that the plains 
of Otis are a delta deposited in the- open sea. South of these plains the 
system becomes discontinuous. After a gap of somewhat more than a mile, 
a rather broad ridge of very round gravel, cobbles, and bowlderets begins 
a short distance northwest of the tannery in Mariaville and extends nearly 
south for 3 miles. Another ridge lies about 1 mile west of this, situated in 
the southeast part of Otis, and it extends farther south than the first, so that 
they are arrayed en échelon. These ridges are several hundred feet broad, 
with very gentle side slopes. Two or three miles south of the last-named 
ridge is Beach Hill, a nearly round mound or massive plain of glacial 
gravel, more than one-fourth of a mile in diameter, and rising steeply about 


120 GLACIAL GRAVELS OF MAINE. 


75 feet above the marine clay that covers its base. The top of the plain is 
diversified with low ridges and some not very deep kettleholes, but the top 
is so level, as seen from a distance, as to resemble one of the buttes of the 
Rocky Mountains. After a gap of nearly 2 miles a plain begins on the east 
side of Union River, near the road from Ellsworth to Waltham. ‘This. 
plain is from one-fourth to three-fourths of a mile wide, and, with two 
short gaps, extends to the cemetery, a short distance east of Ellsworth, 
where it ends in a rather steep bluff on all sides except the north. The 
central parts of the plain, measured east and west, contain cobbles and 
bowlderets; to the very south end of the plain, but on the east and west 
margins pass into fine gravel and finally into sand. This plain thus is seen 
to differ much from. the typical delta, yet shows some horizontal assortment 
of sediments, as if the channel within the ice was by degrees enlarged so 
much toward the east and west that the velocity of the current was checked 
in it—indeed, it practically formed a lake within the ice. South of this point 
there is another gap of a mile or more, and then a broad ridge or plain, 
interrupted by a few short gaps, extends southward through Hancock, past 
North Lamoine, and ends not far above sea level near Kast Lamoine, right 
opposite Mount Desert Island. Toward the south the gravel becomes finer 
and soon passes into sand, which is good for building purposes, and large 
quantities of it are shipped to Bar Harbor and along the coast. The plain 
does not become fan-shaped, but remains only from one-eighth to one-fourth 
of a mile wide. While, then, we see the horizontal classification of sedi- 
ments characteristic of the delta, yet this is not the radiating shape of a 
plain deposited in the open sea, when it was free to spread in all directions 
under the action of winds and tides, as it would have been on the rather 
level plains of Lamoine. These facts warrant the interpretation that the 
glacial waters were flowing in a broad channel which opened on the sea and 
formed a sort of bay or estuary, bordered by ice walls at the sides. 

Some of the gaps in this system are pretty long, yet the linear 
arrangement of the several deposits is such that there can be little doubt 
they were all deposited by a single glacial river, with perhaps one or two 
tributary branches. The largest marine delta of the system is situated im 
Otis, above 175 feet elevation and below the contour of 230 feet. 

The length of the system is about 27 miles. 


U. S. GEOLOGICAL SURVEY MONOGRAPH XXXIV PL. VII 


dA. OSAR PENETRATING A LOW PASS, CLIFTON. LOOKING SOUTHEAST. 


The osar 1s a low ridge on which ihe road is made. 


B. BROAD OSAR TERRACE; BUCKSPORT. LOOKING NORTH. 


The road follows the terrace of glacial grave!, which is much obscured by the marine clay that covers al] the lower slopes of the hills. 


HOLDEN-ORLAND SYSTEM. 121 


LOCAL ESKERS NORTHWEST OF ELLSWORTH. 


Some short ridges of glacial gravel are found about 14 miles north- 
west of Ellsworth Falls; another is situated on the line of the Maine 
Central Railroad about 5 miles northwest of Ellsworth; and still another 
near Reeds Pond station, Maine Central Railroad. 

A short ridge, ending in an enlargement at the south which resembles 
a small delta, is found a short distance southeast of Hast Eddington. This 
is near the foot of the northern slopes of the high granite hills extending 
northeast from Orland. The whole deposit is small, but I could find no 
connections. A short glacial stream probably here flowed into a small 
lake, perhaps late in the time of final melting, when the ice next the hills 
was melted, but some yet remained over the open plain to the north. 


HOLDEN-ORLAND SYSTEM. 


This is a well-defined series of rather short plains, ridges, and domes 
or mounds of glacial gravel, separated by gaps. 

It appears to begin near Holden Village, and extends southwest through 
Dedham and Bucksport and appeais to end not far north of Orland Village. 
Toward the north the gaps, though frequent, are not more than one-eighth 
to one-sixth of a mile in length. Going south, we find the gaps increasing 
to one-half a mile, and the ridges at the same time becoming shorter and 
smaller, till they are reduced to mere hummocks or elongated domes, 10 to 
15 feet high. 

The course of this system is southwest, while the other systems of this 
part of Maine trend south or southeast. The topographical relations of the 
system seem to afford a satisfactory explanation of this anomaly. The 
system lies along the western base of the range of high granitic hills before 
referred to as extending from Orland northeastward across Maine and New 
Brunswick. The schists which border the granite on the west weather 
readily, and it was not possible without excavation to find glacial strize in 
the region penetrated by the gravel system. It is therefore uncertain 
whether there was a local deflection of the ice, caused by the hills, which 
corresponded to the direction of the kame system. This is a fine example 
of the discontinuous systems of lenticular or dome-like kames, at least 
toward the southern end of the system. Toward the north the ridges 


2? GLACIAL GRAVELS OF MAINE. 


become longer and approach the short osar type, and are sometimes broad, 
like osar-plains. It should be noted that in the discontinuous systems as 
here defined the gaps are not due to erosion subsequent to the deposition of 
the gravel, and they are as constant and noticeable a feature as the gravels 
themselves. As a class they are quite nearly parallel with the movements 
of the ice during the last of the Glacial period. This makes it probable 
that there was a movement of the ice southwest into Penobscot Bay about 
12 miles along the western bases of the granite hills; but thus far it is not 
proved by evidence of the scratches. 


MOOSEHEAD LAKE SYSTEM. 


The principal branches of this important system were remarkable for 
being very widely separated at the north. They drained the glacial waters 
of a large part of the Penobscot Valley and its tributaries, and poured 
them into the Penobscot Bay by a single channel. Estimating the amount 
of water by the area drained, only three or four of the osar rivers of the 
State probably equaled this river in volume, yet a dozen or more of them 
exceed this in the quantity of sediment they have deposited. With insig- 
nificant exceptions, the system traverses a region of slates and schists, and 
it is the universal law that when an osar river passed through a granite 
region its gravels are many times as abundant as those of rivers im slate 
regions having the same length. The tributaries of this system are all 
easily traced; they left ridges nearly as large as those of the main river. 
The longest one of these is the Medford-Hampden osar. 


MEDFORD-HAMPDEN OSAR. 


On the north it appears to begin as a series of ridges on the south 
shore of South Twin Lake. It passes southward as a single two-sided 
ridge. In crossing Seboois Lake it is said to appear at certain places as 
‘horseback islands,” and farther south it crosses the valley of Schotaza 
Creek obliquely. The above statements are made on the authority of Mr. 
Eber Ames, of Medford, and are confirmed by many others. From near 
Schotaza Creek I have followed the system all the way to Hampden. For 
several miles north of the Piscataquis River it is a ridge 20 to 40 feet high, 
with arched cross section and broad base. The gravel contained many 
cobbles and some bowlderets, all well rounded, which proves that the ridge 


MEDFORD-HAMPDEN OSAR. 123 


extends a considerable distance north of Schotaza Creek. It reaches the 
Piscataquis River at the mouth of Schoodie Stream in Medford. The gen- 
eral course of the Piscataquis is east, but in Medford it bends sharply to 
the north for more than a mile and then resumes its eastward course. The 
osar reaches the river just where it makes this last bend eastward and fol- 
lows the western bank for about 1 mile, and then crosses the river. The 
river in its eastward course impinges against the base of the osar and is 
deflected by it nearly one-fourth of a mile northward before cutting through 


Fic. 10.—Osar cut by the Piscataquis River at Medford Ferry. 


it. The ridge is here from 20 to 30 feet high, and is in part covered by the 
sedimentary sand and clay which constitute the valley alluvium. This 
place is not far from the upper limit of the sea. Medford Ferry is situated 
just at the point where the Piscataquis breaks through the osar (see fig. 10). 
From this point southward the road to Medford Center follows the ridge for 
a short distance and then passes east of it. The osar extends about one- 
fourth of a mile west of Medford Center and, still rising above the Piscata- 
quis River, it penetrates a low pass in Medford and Lagrange. It is here 
somewhat discontinuous, and in places takes the form of the osar-plain, 


124 GLACIAL GRAVELS OF MAINE. 


especially for some miles south of the divide. In an excavation between 
Medford and Lagrange, bowlderets and bowlders 2 to 3 feet in diameter, all 
well rounded and polished, were abundant as far down as the excavation 
reached—6 to 8 feet. The osar passes about half a mile east of Lagrange 
station. A short distance south of this point the Bangor and Aroostook Rail- 
road comes near the ridge, and for several miles in Lagrange and Alton it is 
constructed along the base of the osar. A wagon road is laid out on the top 
of the osar for many miles. In this part of its course it is a broad ridge or 
narrow plain with gentle lateral slopes and arched cross section, rising 10 to 
30 feet above a very level plain of marine clay. Both the clay and the ridge 
are sprinkled with floe bowlders. At Pea Cove, Alton, the ridge becomes 
narrower, and has steeper lateral slopes from this point southward through 
Oldtown and Orono, on the west side of the Penobscot. In Veazie the 
ridge begins to be interrupted by short gaps. ‘These gaps are especially 
noticeable south of Mount Hope Cemetery, situated not far north of Bangor. 
Mount Hope itself is a part of this gravel system. ‘The next gravel of the 
series is on the east side of the Penobscot River in Brewer, just above the 
railroad bridge, Bangor. The next gravel is the ridge at what is known as 
High Cut, where the Maine Central Railroad cuts through an elongated 
dome of this series in the southeastern part of Bangor. In like manner, a 
series of short and broad ridges, separated by intervals of one-fourth mile 
to more than 1 mile, extends along the west side of the Penobscot River 
through Hampden and joins the main system not far west of Ball Hill 
Cove, near the north line of Winterport. 

A study of the glacial gravel and of the drift of the Penobscot Valley 
will show the great difference between glacial and river gravels in Maine. 

The course of this osar is wholly within a gently rolling plain, much 
of which is as level as the prairies. The base of the ridge is more or less 
covered with clay containing marine fossils as far north as Alton, and per- 
haps farther. Sedimentary clay is found in places along the top of the 
pass In the northern part of Lagrange. If this were marine clay we might 
expect a marine delta in the valley of the Piscataquis a few miles north- 
ward. There is no such delta, and the history of the Medford-Lagrange 
pass seems to be this: First, in a rather broad channel within the ice, an 
osar-plain was deposited. Subsequently the channel, by lateral melting, 
became still broader, and the supply of water was no longer able to main- 


MOOSEHEAD LAKE OSAR. 125 


tain a swift current in the broader channel. Clay was then laid down on 
the flanks of the previously formed osar-plain—osar border clay. 

In places the sea waves have washed down some of the top of the osar 
and strewn the gravel over the adjoining clay. This osar is nowhere very 
high, and it does not spread out into broad plains, like many of the 
systems, yet it is so continuous north of Veazie that it contains a large 
amount of gravel. ‘lhe meanderings of this osar do not in general depend 
on any very evident surface features of the land. 

Its length is about 60 miles, from Hampden north. 


MOOSEHEAD LAKE OSAR. 


This appears to be the longest tributary of the system. It is uncer- 
tain how far a ridge of glacial gravel extends in the floor of Moosehead 
Lake. Gravel, probably glacial, appears on Hogback and Sandbar islands 
in the midst of the lake. An osar appears on the western shore about 3 
miles north of the so-called Southwest Cove of the lake. It follows the 
west shore to the foot of the lake in Greenville, and thence runs southward 
in a nearly straight course over a low divide in Shirley. From Shirley 
northward the ridge is quite continuous, but while following the Piscataquis 
Valley in Blanchard and Abbott on a down slope of about 50 feet per mile 
the gravel is much interrupted for several miles, partly by recent erosion. 
Near the north line of Abbott a plain of sand and gravel, now much eroded, 
appears in the midst of the valley. <A two-sided ridge extends for some 
distance near Upper Abbott, but its summit has nearly the same level as 
terraces which border both sides of the valley. This appears to be a ridge 
of erosion, though it may have along its axis a core of coarser matter than 
is contained in most of the plain. The stones of the ridge and terraces are 
well rounded, like those of the glacial gravels, but, on the other hand, the 
gravel extends from side to side of the valley, like river alluvium. This 
condition prevails for several miles in Abbott. Much of this sand and 
gravel is glacial, but the broad alluvial ridges and terraces of the Piscataquis 
Valley in Abbott present a complex problem. Part of it seems to be an 
osar-plain, part is a frontal delta, part of it may have been deposited in a 
glacial lake, and in part it is composed of river drift. The very round 
shapes of the stones of what appears to be valley drift may best be 
accounted for as an incident in the final melting and retreat of the ice. If 


126 GLACIAL GRAVELS OF MAINE. 


the ice still remained over the Moosehead region to the north, the glacial 
streams would bring down well-polished sediment, while, when the ice had 
melted over the Piscataquis Valley, this rounded sediment, as it was poured 
out by the glacial streams on the steep slopes in Blanchard, would be 
transported by the swift Piscataquis River and deposited on the more gentle 
slopes in Abbott. In this way we may account for valley drift containmg 
stones having the shapes of the glacial gravels. Of course the stones would 
be somewhat rounded while being transported by the river, but these stones 
are rounder than I find in the beds of even the swift streams that come 
down from Mount Katahdin. With respect to the ice they were frontal 
matter. ; 
From Abbott a line of ridges and terraces of unmistakable glacial 
gravel, interrupted by several short gaps, is found on the south side of the 
Piscataquis River, extending eastward through Guilford and Sangerville. 
It then turns southeastward and follows the valley of Black Brook (a 
stream flowing northwest into the Piscataquis River) past Dover South 
Mills to the “Notch” in the northeastern part of Garland. All the way 
from Abbott to the Notch the ridges are in general broad and _ plain-lke, 
some of them 50 and even 70 feet high, and are separated by frequent 
gaps. Near Dover South Mills there ave two parallel ridges for nearly < 
half mile, which inclose a deep elongated basin. This enlargement of the 
system about two-thirds of the distance up the slope closely corresponds 
to the plexus of reticulated ridges in Prentiss, also on a northward slope. 
The Notch is a remarkably low pass which forms a natural gateway 
through the range of rather high hills which border the Piscataquis Valley 
on the south. The top of the pass is less than 100 feet above the Piscata- 
quis River at the mouth of Black Brook. Approaching the Notch from the 
northwest, many ridges and irregular terraces and mounds of glacial sand 
and gravel are seen along the south flanks of the main ridge. Part, if not 
all, of these are due to irregular erosion, by springs and streams, of a plain 
of rather fine sand and gravel which was laid down at the side of the main 
ridge of coarse gravel and cobbles. As a whole, this plain appears to cor- 
respond to what I have termed the broad osar. In this case an osar was 
first formed. Subsequently the channel became enlarged, not on both 
sides, as usually happens, but almost wholly at the south side—the side 
away from the glacial flow. In this broad channel was deposited a plain of 


MOOSBHEAD LAKE OSAR. 127 


finer sediment which was more nearly horizontally stratified than the coarse 
gravel of the ridge formed in the narrow channel. 

There is much silt and clay covering the upper part of the valley of 
Black Brook. I have no accurate data as to the difference of level between 
the Notch and the Piscataquis River. By measurements with the aneroid, 
taken at several hours’ interval, the difference is but little short of 100 feet. 
If so, the clay of the valley of Black Brook near the Notch is not due to 
the floods of the Piscataquis, being higher than the terraces of that river. 
Besides, these clays are so abundant that it seems improbable that so large 
an amount of sediment could be carried several miles along a backwater 
lake. A much more probable theory is that the clays were deposited late 
in the Ice period, when the broad channel of the osar-plain had become 
still further broadened and the ice next the hills had melted, so that the 
valley of Black Brook formed a lake between the hills on the southeast and 
the ice which still covered the valleys of Black Brook and the Piscataquis 
River to the northwest. This lake would for a time overflow southward 
through the Notch, and would cease to be a lake when the ice over the 
Piscataquis Valley had melted so that the waters could escape along the 
present lines of drainage. Into this lake considerable mud would for a 
time be brought by glacial streams. 

Just at the north end of the Notch the gravel system is joined by a 
tributary branch. It appeared to be short. I traced it for one-fourth of a 
mile, when it seemed to end. I afterwards regretted that I did not explore 
the country to the north, as it is possible a discontinuous series of kames 
may extend in that direction. The osar-plain is fully one-eighth of a mile 
broad at the north end of the Notch, and extends southward about one-half 
mile. Then for another half mile, where the steep hillsides almost meet at 
the bottom so as to form a V-shaped valley, a few very round cobbles and 
bowlderets are found here and there and testify that the osar river flowed 
through the Notch. ‘The force of current must have been very great in 
order to leave so little gravel in the valley. Bare ledges abound, yet here 
and there considerable areas of till have escaped denudation. The till was 
the fine clayey till characteristic of the slate regions. The rounded osar 
stones distinctly overlie the till, and therefore must have been deposited at 
a later stage. I made no excavations, and do not know with certainty that 
there are no rounded osar stones mixed with the till, but in the banks of a 


128 GLACIAL GRAVELS OF MAINE. 


small brook no such stones appeared as part of the till. ‘There is here no 
proof of a landslide of till from the hillsides, and no proof that till dropped 
down into a subglacial tunnel from above subsequent to the deposition of 
the glacial gravel. The evidence strongly favors the following conclusions: 
(1) The till was first Gn order of time) deposited beneath the ice as a ground 
moraine. (2) Subsequently part of this till was washed away by the glacial 
river. (3) The fact that a considerable part of the till escaped denudation, 
notwithstanding the large size of this glacial river, proves that it must have 
presented considerable resistance to erosion; and this conclusion follows 
whether we consider that the osar river flowed in a subglacial tunnel or in 
an ice canyon open to the air. (4) The fact, then, that the glacial gravels 
often overlie uneroded till is not fatal to the theory that the kames and 
‘osars were deposited in subglacial tunnels. The fact is, the ground moraine 
was a very tough, compact mass, and not easily eroded even by a rapid 
glacial stream. Besides, it is not proved that in all cases subglacial streams 
would erode the till while those flowing in superficial channels would not. 
(5) The absence of till overlying the osar leaves us without direct proof that 
the osar river here flowed in a subglacial tunnel. 

At the south end of the Notch the gravel and cobbles spread out into 
a fan-shaped plain about one-half mile long and half as broad. The plain 
has been eroded by a small stream which flows southward through its cen- 
ter, so that the plain of original deposition has been cut into two parallel 
terraces separated by a valley of erosion. The lateral terraces are also 
intersected by several transverse valleys of erosion, so that what must have 
been originally a continuous plain is now a series of detached terraces and 
mounds. The gravel is coarse at the north end of the plain and grows 
much finer toward the south. It was a small delta, deposited either in a 
glacial lake or in the sea. The plain is bordered by clay, and a sheet of 
clay extends from this point all the way to the sea. I found marine fossils 
in this clay at Kenduskeag Village, a few miles south of this place. It is 
certain that the sea extended nearly to the Notch, but exactly how far I 
have not been able to determine. If the clays that border the osar all the 
way from the Notch southward are not wholly marine, then we must regard 
them as osar border clays toward the north, i. e., deposited in the broad- 
ened osar channel at the sides of the previously deposited glacial gravel. 

South of the gravel plain at the south end of the Notch there is an 


MOOSEHEAD LAKE OSAR. 129 


a 


apparent gap in the gravels of somewhat more than a mile. In Charleston, 
not far north of the Corinth line, a ridge rises above the clay. It is low 
and has gentle side slopes. It extends southeastward for several miles, 
passing about one-half mile west of East Corinth, here becoming higher 
and narrower and with steeper sides. Near here many boiling springs 
issue from the base of the ridge. The ridge is bordered on each side and 
partly covered to a height of 10 or more feet by sedimentary clay. The 
gravel is readily permeated by the rains, but the water can not readily 
escape from the sides of the ridge on account of the rather impervious 
clay. In this natural channel it runs lengthwise of the ridge. Coming to 
the lower grounds, it fills up the gravel to the top of the clay and boils 
over the top or escapes through the clay near the gravel. In the lowlands 
wells dug in the gravel ridge reach water, but the uplands are so dry that 
the winds circulate freely through the gravel and cobbles. The cellars of 
houses built on the gravel in such situations are exposed to rapid currents 
of air in time of high winds, and have to be cemented tight before the 
houses are habitable. In various parts of the State great numbers of wells 
have been dug in the glacial gravels in such situations that it was inevitable 
that all the surface water would be at once conducted away to lower levels, 
and where it would be impossible to get water without penetrating the 
gravel into the underlying till, and the loose gravel generally caved in 
before this depth could be reached. 

In Corinth the osar and the neighboring clay are in a few places 
sprinkled with bowlders having till shapes, probably dropped by ice floes. 
The ridge is for several miles parallel with the Kenduskeag River. Near 
the south line of Corinth the osar crosses the Kenduskeag as a shallow 
bar extending across the stream. The water plunging over the bar has 
eroded a deep hole directly below it, known as the “Salmon hole.” In 
general, if the explorer of glacial gravel hears of a salmon hole on an 
east-and-west stream, he may at once suspect it is formed where a stream 
flows over a submerged osar. The osar now turns southwesterly and soon 
disappears on the surface, yet can be readily traced for about a mile beneath 
. the marine clay. By inquiries concerning the nature of the soil found in 
digging wells, it is often possible to trace an osar which is deeply hidden 
beneath the clay, or perhaps may show as a low mound covered by clay. 


As a typical instance, and in order to fully explain the methods employed 
MON XXXIV 9 


130 GLACIAL GRAVELS OF MAINE. 


in this investigation, I give a single observation made about a half mile 
south of where the osar crosses the Kenduskeag River. 

The surface was wholly covered by clay and silty clay. A well had 
been dug 200 feet or more in front of a house. This was an unusual 
position and required investigation. Inquiry showed that two or three wells 
had been dug near the house, all penetrating 3 or 4 feet of clay, and, 
deeper, dry gravel and cobbles, until the wells caved in. One of these 
wells was 80 feet in depth. Afterwards a well was dug a few rods back of. 
the house, reaching water at the depth of 15 feet in clay, and the same 
experience was had when the well in front of the house was dug. The 
house was situated right on the line of the buried osar prolonged. Hence 
it was evident that the osar had disappeared simply because it had been 
flanked and covered by 80 or more feet of clay. 

With a few short gaps, where it may exist, but, if so, is covered. by the 
marine clay, the osar continues southwestward over a rolling country. 
Two miles north of Hermon Pond it spreads out into a hill or table-like 
plain, varying from one-fourth to one-half mile wide and more than 1 mile 
long, rising 50 feet above the marine clay that covers its base. The surface 
is rolling and incloses shallow basins. Although not large as compared 
with the plains of many of the gravel systems, unless we except the plains 
in Abbott, these are probably the largest plains in the whole line of the 
system. They are not true delta-plains, ending in sand and clay. After a 
short apparent gap the ridge begins again and extends past Hermon Pond 
station to the north shore of Hermon Pond. The ridge is cut through by 
the Maine Central Railroad just at the station, being there covered by 
marine clay, and a short distance south of that point the gravel has been 
extensively excavated by the railroad company. The gravel reappears on 
the south shore of Hermon Pond and passes a short distance east of West 
Hampden. From this point southward the gaps become a constant and 
essential feature of the system. South of here the ridges are nowhere more 
than 1 or 2 miles long, and often they are so short and broad that they may 
be called plains or domes rather than ridges. These discontinuous gravels 
extend in nearly a straight line from West Hampden to Winterport Village, 
passing nearly 1 mile west of Ball Hill Cove, near which point it unites | 
with the Medford-Hampden branch. The gravel appears at the cemetery, 
Winterport, and at various gravel pits in the southern part of that village 


‘NOLYOOLS “LNIOd AGNVS ‘AVG LOOSHONSd 40 SYOHS SHI LV ONIGNS ¥vSsoO 


IA “Id AIXXX HdVHSONOW s ASAYNS 1WOISOIOSS “Ss “N 


KENDUSKEAG-HAMPDEN BRANCH. 1511 


it is overlain by clay. Within a mile south of the village the system comes 
obliquely down to the shore of the Penobscot River, and its course lies 
within a broad bay of the Penobscot River from this point to Frankfort 
Village. It then follows the valley of Marsh River past the bases of the 
high granitic hills which cluster about Mosquito Mountain. From this point 
southward the gravel contains a large proportion of granite and the ridges 
become more nearly continuous. Numerous bowlderets appear, and 
bowlders up to 4 feet in diameter. These in part have till shapes and are 
floe-bowlders, but many of them are water-rounded and polished on their 
unweathered surfaces, and are therefore an integral part of the osar. The 
great size and number of these large rounded bowlders favor the hypothesis 
that they were deposited in a subglacial channel. The system passes 
through Prospect Post-Office, and then soon turns southeast along the 
northern slopes of a range of hills. It comes nearly to Gondola Cove, and 
then turns southward parallel with the Penobscot Bay. As a broad ridge 
it comes down to the shore of the bay at Sandy Point, Stockton, where it 
ends in a cliff of erosion at the beach. The bluff here is near 25 feet high. 
Gravel is reported at Fort Point, in the line of this ridge prolonged. I have 
examined the deposit and am in doubt whether it is glacial gravel or a 
raised beach. 

Its length from Moosehead Lake to Penobscot Bay is about 80 miles. 


KENDUSKEAG-HAMPDEN BRANCH. 


This begins not far north of the south line of Charleston and extends 
southward through the eastern part of Corinth, then southeasterly to Ken- 
duskeag Village, where it abruptly turns southwest to Levant Village. It 
here turns south, and is interrupted by numerous gaps from this point on. 
It crosses a low col, and at the southern end of the pass it makes a sharp 
meander almost west for one-fourth of a mile, and then as abruptly turns 
southward again. The system crosses Hermon Bog and the Maine Central 
Railroad a short distance east of Hermon station. A continuous ridge 
extends from the railroad for about 2 miles, where the system becomes inter- 
rupted by rather long gaps again. This glacial river may have joined the 
Medford branch near Hampden Upper Corner, but my most recent informa- 
tion makes it more probable that it joined the main osar river near the south 
line of Hampden, and that its course lies a mile or more west from the 
Penobscot. I have not personally explored this series in Hampden. 


132 GLACIAL GRAVELS OF MAINE. 


This osar is a ridge from 10 to 50 feet high, and north of Levant it 
has rather steep lateral slopes (see fig. 11). It nowhere expands into broad 
plains, though it is somewhat plain-like south of the railroad in Hermon. It 
begins a few miles south of 
the high hills bordering the 


Piscataquis Valley on the south. 
Except near its north end the 


S 


ee series lies wholly in a region 
Fig. 11.—Sectio 


that was under the sea. At 
Kenduskeag Village the lines of stratification of the ridge are much dis- 
torted, as shown in figs. 12 and 13. 

Its length is about 25 miles. 


“b é 


n of osar; Levant. 


EXETER MILLS-CARMEL BRANCH. 


This branch appears to begin near the northern brow of a hill about 1 
mile south of Exeter Mills and at an elevation of about 100 feet above that 
place. ‘The series for sev- 
eral miles is interrupted 
by numerous short gaps, 
yet is easily traceable to 


Fic. 12.—Crumpled strata near surface of osar; Kenduskeag. Atalayers are 
South Levant and thence crumpled as shown in fig. 13; thelayer ) contains much clay and fine sand. 


through the eastern part of Carmel to join the Moosehead Lake osar some- 
what more than a mile north of Hermon Pond station (see fig. 14). It is 
nowhere a very large ridge, being 10 to 30 feet high. In Carmel it shows 
several remarkable zigzags (see fig: 15). It has been under the sea for 
most of its course, and is often nearly covered on its flanks by niarine clay. 


Fic. 13.—Crumpled strata near surface of osar; Kenduskeag. Enlarged view of strata at a@ in fig. 12. 


In several places it develops into cones considerably higher than the rest 
of the ridge. In one place it expands laterally and incloses a deep kettle- 
hole, and right south of this point is a cone of unusual height. It nowhere 
expands in broad plains. On the north it begins on the south side of the 


MOOSEHEAD LAKE SYSTEM. 133 


valley of the Kenduskeag and several miles south of the high hills lying 
south of the Piscataquis River. It traverses a gently rolling plain. Its 
length is about 12 miles 
from Hermon Pond 
north. 

The following- 
named osars are situ- 
ated between the two 
principal branches of 
the Moosehead Lake- 
Penobscot Bay system. 


The streams which 


Fic. 14._Section across Exeter Mills-Hermon osar, in Carmel. 


drained this portion of 


the ice-sheet would naturally flow into the system, but it may have been at 
a time before the deposition of these glacial grayels. I have not yet been 
able to make out any connection between these and the Penobscot Bay sys- 


Y)} 
is 
MM hy fy 
Ay Ue! 
A 
SMW Yi - 
4 pecase Wee: ¢ 
ES SM Yr z 


Fie. 15.—Meandering of osar; Carmel. The fence is built along the top of the ridge. 


tem. It is probable that the osars next to be named were deposited at a time 
when the ice had receded to the north of the Piscataquis River, and that 
therefore they are independent systems deposited late in the Ice period. 


134 GLACIAL GRAVELS OF MAINE. 


JO MERRY OSAR. 


This osar is said to extend through the wilderness for about 10 miles 
along Pratt Brook, a stream which flows nearly east into the middle of Jo 
Merry (or Jo Mary) Lake. Its course prolonged would lead it near South 
Twin Lake, and it may be an extension of the Medford-Hampden osar. 


ROACH RIVER OSAR. 


Roach River flows westward into Moosehead Lake. An osar follows 
the valley of this stream quite continuously for about 12 miles. Large 
pebbles and cobbles, with some bowlderets, make up the larger part of the 
ridge. The stones are not much rounded at the angles, though they plainly 
have polished surfaces, an indication that the system does not extend much 
farther to the north or west. From the head waters of Roach River low 
passes lead down the valleys of both the east and the middle branches of 
Pleasant River. These two branches unite near the north line of Brown- 
ville, and from near their junction a plain of sand and gravel containing 
many very round pebbles and cobbles extends up both valleys for about 
3 miles northward. Here my exploration ended, and my information as to 
the valleys above this point is indefinite and conflicting. The preponder- 
ance of evidence favors the hypothesis that the principal glacial streams 
flowed down the valley of the east branch of Pleasant River. It length is 
about 25 miles. 

KATAHDIN IRON WORKS OSAR. 


A two-sided ridge from 15 to 30 feet high extends along the valley of 
the west branch of Pleasant River for several miles above the Katahdin 
Iron Works. Much well-rounded gravel is found along the valley below 
this place in Williamsburg which resembles a delta in composition and 
structure. The most probable theory as to its origin, according to my 
present information, is that glacial rivers flowed down the valleys of all 
three branches of the Pleasant River at a time when the valley of the main 
river to the south was bare of ice. The well-rounded gravel was thus 
brought down to the extremity of the ice and then spread as valley drift 
over the open valleys. This is an interesting region and deserves further 
study. 

A plain of well-rounded gravel more than 2 miles long and from one- 


SYSTEMS OF GLACIAL GRAVELS. 135 


fourth to one-half mile wide is found on the west side of Pleasant River a 
short distance east of Milo Village. A line of clay covers the Piscataquis 
Valley from Howland to Milo, and then silty clay extends up the Piscataquis 
to Dover and up the Pleasant River to Brownville. The gravel of the 
plain east of Milo Village is so much coarser than the drift of the Pleasant 
River Valley north of the plain for several miles, and the slopes of the 
valley are so gentle, that it is quite certain this plain is glacial gravel. The 
plain shows several of the characteristics of the delta. The Pleasant River 
glacial gravels do not seem to have connections south, a fact which strongly 
supports the conclusion that they were terminated by delta-plains at the 
ice front during the final melting and recession of the great glacier. 


LILLY BAY-WILLIMANTIC OSAR. 


A medium-sized ridge leaves Moosehead Lake at Lilly Bay. The 
gravel is here not much rounded. The ridge is described as following a 
rather crooked line of low passes southward, and then down the valley of 
Wilson Stream, expanding into broad plains in Willimantic, west of Sebec 
Lake. No glacial gravel extends along Sebeec Lake and Stream, and I 
can not trace any extension of this system south into Guilford or Dover. 
This makes. it highly probable that the broad sedimentary plain of Wilson 
Stream above Sebec Lake is really a frontal plain composed of matter 
poured out by glacial streams into the valley in front of the ice, at a time 
when the ice had retreated to this place. There is very little alluvium of 
any kind along Sebec Stream, the outlet of Sebec Lake, until we come east 
to within 2 miles of Milo Village, when the valley widens and is covered 
with silty clay continuous with that of the Piscataquis and Pleasant River 
valleys. This clay is just such a deposit as would be formed in the valley 
by the Gletschermilch of glaciers still existing 20 miles or more to the 
north. 

We now pass beyond the region included between the two principal 
branches of the long Moosehead Lake-Penobscot Valley system. 


e 


ETNA-MONROE SYSTEM. 


We now reach a part of the State where those parts of the gravel sys- 
tems which contaim gaps as a constant and conspicuous feature are as long 
as or longer than those parts where the ridge is continuous. 


136 GLACIAL GRAVELS OF MAINE. 


A series of ridges separated by intervals of various lengths up to 13 
miles begins in the south part of Stetson near the top of a rather low east- 
and-west hill. The series passes around the west and south sides of Etna 
Pond and then southeastward. It passes a few rods south of Carmel station 
of the Maine Central Railroad, and within 2 miles turns rather abruptly 
southward along the main tributary of the Soudabscook River. In this 
part of its course it is nearly continuous. For several miles in the northern 
part of Newburg it takes the form of an osar-plain, i. e., a level plain of 
well-rounded gravel filling the bottom of the valley, being bordered on each 
side by a sheet of sedimentary clay which extends back to the hills. The 
clay-and-gravel deposits have substantially the same upper level or surface. 
The osar does not follow the axis of the valley exactly, but is often nearer 
to one side. In the central part of Newburg the gravels leave the valley 
of the Soudabscook and go south up and over a hill fully 150 feet high. 
Above this point the valley of this stream contains only a scanty valley 
drift reaching scarcely 5 feet above the stream, a great contrast to the broad 
and deep sheets of gravel and clay which fill the part of the valley where 
the osar river flowed. This clay bordering the central gravel plain is a 
good example of what I have named the osar border clay. The gravel 
itself was deposited in a rather broad channel in the ice. This channel sub- 
sequently broadened so as to extend across the whole valley and the clay 
was deposited at the flanks of the older gravel plain. A lake 150 feet deep 
would naturally gather here on the north side of the hill, but it was 
inclosed by ice walls on the sides (at least most of the time of its existence), 
otherwise it would have extended up the valley for some miles and the 
upper part of the valley would be covered by lacustrine sediments. 

On the hill above referred to the gravel is much interrupted. At the 
southern base of the hill it spreads out into a broad deposit nearly one-half 
mile across. This is in the valley of another branch of the Soudabscook, 
which flows northeastward, past South Newburg, into Stetsons Pond at 
West Hampden. The gravels take an unusual form. There are several 
gently sloping terraces, rising one above the other, each separated from the 
adjoming ones by rather steep bluffs which are nearly parallel with the 
strike of the hillside. The higher terraces on the north are narrower and 
composed of coarser material than those on the south. The deposit as a 


ETNA-MONROE SYSTEM. Be 


whole has some of the characteristics of a fan-shaped delta. A plain of 
marine clays extends from this point eastward to the Penobscot River. 
Between this gravel plain and South Newburg, 2 miles distant, there are 
several small low ridges or plains of rather fine gravel, which fact favors 
the conclusion that during the final melting there was a limited overflow 
from the larger plain (then a glacial lake) eastward into the arm of the sea 
which then occupied the valley where now is South Newburg. South of 
the delta-plain above mentioned lies a region of valleys and low hills. The 
glacial gravels cross these as a series of broad ridges, separated by gaps, 
which soon expand into a pretty large plain, about 2 miles long and three- 
fourths of a mile wide. Along one part of the plain is a ridge rising above 
the rest of the plain. This ridge expands in places into reticulated ridges 
inclosing deep kettleholes. Bordering this ridge, which is composed chiefly 
of large pebbles, cobbles, and bowlderets, is the rather level plain of finer 
sand and gravel. Evidently the central ridge was deposited in a channel 
between ice walls. The bordering plain is a delta, deposited either between 
ice walls in a glacial lake or in the sea. This plain is situated east and 
northeast of Monroe Village, and the Monroe Fair-ground is situated on it. 
‘Marine clays widely cover the valley of Marsh Stream to a point far west 
of Monroe. South of Monroe Village the gravel takes the form of lenticu- 
lar ridges or elongated domes. From this point south the gaps are a very 
regular and constant part of the system, and they do not seem to depend 
on the surface features of the land for their distribution; at least if there be 
such a dependence it is not easily detected. The system extends southward 
through Monroe, crosses a low divide in Swanville, skirts the western side 
of Goose Pond, and then takes a nearly straight course to Belfast Bay, near 
the line between Belfast and Searsport. South of Goose Pond the system 
for some miles takes the form of a low plain one-eighth to one-fourth of a 
mile broad. The material becomes finer on the south, and is a delta-plain, 
laid down probably in a bay of the sea inclosed at the sides by glacial ice. 

The gaps between these separated gravel deposits are not due to ero- 
sion, unless locally here and there at the crossing of streams, but the gravel 
was deposited discontinuously in this way. Between the separate deposits 
lie undisturbed till or marine clay. 

The length of the system, from Stetson to Belfast Bay, is about 35 miles. 


138 GLACIAL GRAVELS OF MAINE. 


LOCAL ESKERS IN JACKSON. 


A ridge of subangular glacial gravel extends about one-fourth of a mile 
north from Jackson Village. About 2 miles east of the village is a plain 
nearly 1 mile long and one-fourth mile wide. It is near Fletchers Mill, on 
Marsh Stream. Another similar plam is found near Marsh Stream at the 
mouth of Emery Brook, about 2 miles west of Monroe Village. The gravel 
of these small plains is coarser on the north and west; they are probably 
deltas deposited in the arm of the Penobscot Bay which once extended for 
many miles up both branches of Marsh Stream. 

The till in Jackson shows a great variety of heaps and ridges, probably 
owing to the fact that Jackson lies just south of the high hills of Troy and 


Dixmont. 
WALDO-BELFAST BAY SYSTEM. 


This is a short series, consisting of short and broad ridges or plains, 
also of domes or mounds of glacial gravel. The system begins in the north- 
eastern part of Waldo and extends southward along the valley of Westcott 
Stream to City Point, at the head of Belfast Bay. Toward the south the 
deposits continue to grow smaller, and the last of them that is now above 
the sea is only a small hummock, not more than 75 or 100 feet in diameter 
at the base. The system is discontinuous throughout its whole course. 

It is 5 miles long. 

BROOKS-BELFAST SYSTEM. 


This is a discontinuous series. It appears to begin in the northeastern 
part of Brooks, perhaps extending into Jackson. It crosses the valley of 
the south branch of Marsh Stream about 1 mile east of Brooks, here being 
joined by a short branch from the northwest. It then goes up and over 
the hills by the same pass in which the Maine Central Railroad is con- 
structed, and its course lies near the railroad in the valley of Westcott 
Stream to Waldo station. The railroad here turns eastward and follows 
the lower valley of Westcott Stream, while the gravel takes a straight 
course southward past Evans Corner to near the Head of the Tide, Bel- 
fast. Near Waldo station the, series takes the form of. broad ridges and 
rather level-topped plains bordered by marine clay. These are apparently 
delta-plains, but since they do not spread out in fan shape, as they could 
easily have done if the glacial river flowed into the open sea, they: must 


SYSTEMS OF GLACIAL GRAVELS. 139 


have been deposited in a glacial lake or in a broad channel inclosed between 
ice walls and opening into the sea. South of the delta-plains the lenticular 
mounds grow smaller, and the last known deposit of the series is only a 
small hummock, which was once wholly covered by marine clay and laid 
bare by excavations. 

The system is about 15 miles long. 


LOCAL ESKERS IN DEXTER. 


About 2 miles east of Dexter on the road to Garland are two small 
ridges or hillside eskers. They begin on the south side of a long sloping 
hill, not far above its base, and extend out into the rather level valley a 
short distance. They enlarge somewhat at their south ends, but not into a 
well-developed delta, such as ends in sand and finally clay. These ridges 
are less than one-fourth of a mile in length. 

A short ridge of glacial gravel is found near the railroad station in 
Dexter Village. The valley of Dexter Stream is covered by very abun- 
dant alluvium of uncertain origin. It is more abundant than usual in 
a valley of this size. It is possible some of this rather fine sediment is 
an osar-plain connecting with the system next to be described. I have 
not explored the valley north of Dexter Village, but have recently heard of 
bogs without visible outlets being found not far north of Dexter. If this 
is so, there probably is a system of glacial gravels along this stream, and 
the fine silt and clay in the valley below Dexter may be frontal matter 
derived from this stream at a time when the ice had retreated to some point 
near or north of Dexter. This interpretation would well accord with 
the finding of the hillside eskers east of the village. 


CORINNA-DIXMONT SYSTEM. 


As above noted, this system may extend to Dexter or farther north, but 
I was not able to determine the limit with certainty. A well-defined series 
of glacial gravels is found in the valley of Alder Stream for 3 miles north of 
Corinna, and thence southward to the junction of this stream with Dexter 
Stream. The gravel takes the form of level plains in several places, and 
there are a number of gaps. Its course crosses Newport Pond. It appears 
as an osar ridge on the south side of this pond, and takes a quite straight 
general course southward past East Newport station, on the Maine Central 


140 GLACIAL GRAVELS OF MAINE. 


Railroad, to Plymouth Village. ‘The road from East Newport to Plymouth 
is made on top of the ridge for several miles. Just north of Plymouth 
Village the road crosses a hill about 125 feet high. The gravel system 
here bends to the east of the road for a short distance and crosses the hill 
at an elevation about 50 feet lower than the road. At the northern base 
of this hill there is a plain of gravel with much sand. The plain is near 
one-fourth of a mile wide, and indicates a checking of the glacial streams 
north of the hill) From East Newport to this point the osar traverses 
a plain that is covered by sedimentary clay—border clay. We have seen 
that the osar river turned east in order to cross the hill north of Plymouth 
at a low part of the hill; but by bending about the same distance west 
the stream could have flowed around the hill along a valley of natural 
drainage. The gravel is scanty on top of the hill, but becomes abundant 
near its southern base in the outskirts of Plymouth Village. ‘The ridge 
next crosses Plymouth Pond, plainly showing as a natural roadway extend- 
ing across the valley, but it is submerged for a short distance. The road 
is made on top of this natural embankment while crossing the pond and 
bordering swamp. The system now begins to ascend a hill 100 feet high, 
and at once expands into a plexus of broad, rather parallel ridges inclosing 
several kettleholes. Approaching the top of the hill, the several ridges 
coalesce into a flat-topped plain near one-eighth mile wide. It is com- 
posed chiefly of sand, and is a fair type of the broad osar. No gravel is 
found on the top of the hill for a short distance; then it begins again and 
continues down the hill to North Dixmont. It here takes the form of a 
narrow ridge 50 to 75 feet high, having steep lateral slopes. In several 
exposures the strata, as shown in cross section of the ridge, dip mono- 
clinally eastward, as if the channel in the ice enlarged on the east side 
toward the open valley. The ground rises to the west, and this makes it 
a possible hypothesis that the ice flowed eastward enough to compensate 
for the natural enlargement of the channel westward. 

Going southward, we find the ridge growing broader and lower, and it 
finally spreads out into a rather level plain one-eighth of a mile wide. This 
becomes finer in composition toward the south, and finally becomes sand. 
It is bordered at the sides and south end by a rather steep bluff, which 
overlooks the valley of Martin Stream. This is a small stream which rises 
in Troy, then flows northeastward through Dixmont, when it turns north- 


CORINNA-DIXMONT SYSTEM. 14] 


west past Plymouth Village and empties into the Sebasticook River a few 
miles below Newport Village. In Dixmont the valley of this stream is 
very level and a half mile or more broad. A continuous plain of clay and 
silty clay overlying fine sand (the reverse order of the ordinary valley 
alluvium) is found in this valley all the way from Troy, through Dixmont 
and Plymouth and thence along the Sebasticook and Kennebec valleys, to 
the sea. This clay is proved by its fossils to be marine as far east as Pitts- 
field, and perhaps as far as Newport. I have often suspected that a narrow 
arm of the sea connected the Kennebec and Penobscot bays of that time, 
along the low ground where Etna Bog is. Now the gravel-and-sand plain 
which seems to terminate the Corinna-Dixmont system has the general 
character of a delta deposited where rapid streams flowed into a body of 
still water and are rapidly checked. At once our attention is called to the 
large plain of fine sediment in the valley of Martin Stream, in which this 
delta lies. This stream is only a small brook, and ordinarily streams of 
that size would deposit only a very little alluvium. Evidently, at the time 
this delta-plain 2 miles southwest of North Dixmont was being formed the 
valley of Martin Stream in Dixmont and Troy was in large part bare of 
ice, and was either occupied by a lake contained between the ice on the 
north and the hills over which the ice had melted at the south, or was filled 
by an arm of the sea. But the Kennebec Bay of that period could reach 
this place only along the valley of Martin Stream through Plymouth, and 
if the sea extended from that direction the delta would have been formed 
in the valley of Martin Stream at Plymouth Village instead of several 
miles south of that place. It is evident that when the delta southwest of 
North Dixmont was being deposited, the ice must still have remained at 
Plymouth Village, and this would prevent any communication with the sea 
in the Kennebec Valley. Was there an arm of the sea in the valley of 
Martin Stream which connected with the Penobscot Bay? I have traced 
the marine clay from the Penobscot River as far west as Etna Pond, but 
between that point and Plymouth is an area not explored. According to 
Col. A. W. Wilder, quoted in Wells’s Water Power of Maine,’ the elevation 
of Plymouth Bog is 256 feet, and that of Plymouth Village 275 feet. As 
elsewhere suggested, the sea may have stood at a higher elevation in the 
interior than on the coast, but in the absence of direct proof to that effect, 


1The Water Power of Maine, by Walter Wells, p. 89, Augusta, 1869. 


142 GLACIAL GRAVELS OF MAINE. 


the clays of the valley of Martin Stream in Plymouth and Dixmont must 
be considered as probably having been deposited above the highest level of 
the sea, and therefore in a lake contained between the ice which was still 
unmelted toward the north and the high east-and-west hills of Troy and 
Dixmont on the south. If so, where did the supposed lake overflow? 
There are two low passes by which the water of such a lake could have 
escaped southwestward into the Sandy Stream Valley in Thorndike, after 
the waters had accumulated to a depth of about 100 feet, provided no 
barrier of ice then existed in that direction. But no clays analogous in any 
way to those of the Martin Stream in Dixmont are found along these val- 
leys, and hence there is no proof of an overflow this way; neither do I 
find proof of such overflow westward into Troy. The order of events 
here is probably about as follows: The Corinna-Dixmont glacial river 
emptied for a time into an enlarging glacial lake, inclosed between the ice 
and the high hills on the east and south. The outlet of this lake was 
toward the Penobscot Bay or in some unknown direction. During the 
retreat of the ice the glacial water may have escaped into the open valley 
of. Martin Stream at or near Plymouth Village, but if so it could have been 
for only a short time. The gravel plain at the north base of the hill 
situated just north of Plymouth Village may point to another glacial lake, 
formed north of that hill, and the clay bordermg the osar northward to 
East Newport may have been deposited by a broad channel which practi- 
cally formed an enlargement of this lake. There are plains of sedimentary 
clay in Plymouth extending an unknown distance northeastward toward 
Etna Bog, and these may mark an overflow to the Penobscot Bay. How 
far this is marine remains to be determined by future investigation. 
The length is about 20 miles.* : 


EAST TROY KAMES. 


About 3 miles southwest from the delta-plain in which the Corinna- 
Dixmont system ends, a discontinuous series of short ridges and cones of 
glacial gravel begins on the hills north of Martin Stream, crosses the valley 
of that stream near Kast Troy, and then ascends the hills lying to the south 
to a height of about 100 feet. It appears to end in a thin gravel plain a 
little north of a low pass leading into Jackson. Not far north of where the 


' The clays extending from Dixmont eastward are now (1893) considered by me to be marine. 


TROY-BELFAST SYSTEM. 143 


gravel disappears is a cone of gravel and cobbles 80 feet high. The Brooks: 
Belfast and Troy-Belfast systems are both so situated that this short glacial 
river might connect with either of them, but I have not been able to trace 
any connection with them. The clay in the valley of Martin Stream 
overlies these gravels; hence the flow of this glacial stream dates previous 
to the time when the terminal delta of the Cormna-Dixmont system was 
deposited in a body of water then filling this valley. 

This short series does not have a wholly satisfactory beginning or end, 
but I have not been able to trace any connections with other gravels. It 
may at one time have been part of the Corinna-Dixmont system. 

The length is about 3 miles. 


TROY-BELFAST SYSTEM. 


This system appears to begin about one-half mile south of the road 
from West Troy to Troy Post-Office (Troy Corner), as a low, north-and- 
south ridge, which shows numerous meanderings. It lies in a region of 
rather low hills, forming a rolling plain lying north of the much higher hills 
of southern Troy and of Thorndike. At the northern base of these high 
hills this ridge is joined in the southern part of Troy by a rather level 
gravel plain from the west. It is nearly one-fourth mile in length and per- 
haps half as wide. This appears to be a delta, either of a lake wholly 
glacial or of a lake confined between the ice on the north and the hills on 
the south. The gravel system then crosses a low divide in a narrow pass 
and follows the valley of Parsons or Halls Brook for 2 miles southwestward. 
It then abandons this valley and follows a low pass into the valley of 
Higgins’s Stream. It follows this valley southward for several miles, passing 
about one-half mile west of the Friends’ Meeting House in Thorndike. It 
leaves this valley not far from Thorndike Corner, and by a crooked route 
penetrates the hilly region of eastern Knox and the northwestern part of 
Brooks, crossing several pretty high hills. It then follows the valley 
of Marsh Stream, parallel with the railroad, to a point about 1 mile west of 
Brooks Village, when it turns southward along a low valley. It soon goes 
up and over a hill 100 or more feet high and descends to Passagassawawkeag 
Pond. From this point south its course lies in a rather level region in 
Brooks and Waldo. In Waldo it expands into a rather level plain several 
miles long and one-eighth of a mile or more in breadth. The material 


144 GLACIAL GRAVELS OF MAINE. 


becomes finer toward the south, and gradually passes into the marine clay 
at an elevation of 200 feet or a little more. The plain is probably a delta 
deposited in a bay of the sea between ice walls. South of this plain are a 
few small gravel deposits, forming a discontinuous series, with long gaps. 
The system seems to end in the northern part of Belfast. The way in 
which most of the longer gravel systems reach their maximum develop- 
ment at about the contour of 230 feet and then become less and less till 
they end at or not far above the sea, is well expressed by the Western 
phrase, ‘‘peter out.” 

This glacial river brought down a large amount of sediment for so 
short a stream. Its course is circuitous, and for most of the distance is in 
a very hilly country. Five times it left drainage valleys and crossed. hills 
into other valleys, none of the hills being more than 200 nor less than 100 
feet high. Its larger deflections occurred invariably in order that it might 
cross the hills by the.lower passes. 'The system is an instructive example 
of the power of the higher hills to deflect the glacial rivers. When it 
crosses hills, the gravel is usually abundant near the southern base of the 
hills or in the level plains, while it is seanty near the tops of the cols. 

It is about 20 miles in length. 


MORRILL-BELFAST BAY SYSTEM. 


This is a discontinuous system of short ridges, small plains, and len- 
ticular mounds or domes of glacial gravel separated by intervals varying 
in length from one-eighth to one-half of a mile. 

The series begins in the northern part of Morrill and takes a southeast 
course over a level plain past Morrill Village to Poors Mill, in the north- 
western part of Belfast. It then goes up and over a hill about 100 feet 
high and descends the valley of Little River, ending in a beach cliff of 
glacial gravel on the shore of Belfast Bay, a few rods south of the mouth 
of Little River. 

Near Poors Mill the system expands into a somewhat level plain, sug- 
gesting a small marine delta. The whole region traversed by the system 
has been under the sea, and the gravels are more or less covered by the 
marine clay. 

An interesting formation is found in the valley of Little River at the 
road from Belfast to Belmont. The axis of one of the ridges of this sys- 


MORRILL-BELFAST BAY SYSTEM. 145 


tem is shown by the deep cut at the road to consist of till. A central ridge 
of till was covered on both slopes by 10 or more feet of glacial sand and 
gravel, some of it reaching the top of the ridge, and subsequently the whole 
was buried beneath several feet of marine clay. This suggests the ques- 
tion whether a core of till may not often occupy the central and basal por- 
tions of the low rounded ridges of the discontinuous systems of glacial 
gravel. I have examined a large number of the lenticular masses char- 
acteristic of this type of gravels, and this is the only case where they could 
be proved to contain unmodified till. Yet these excavations seldom went 
to the bottom of the deposit, and their number is small as compared with 
the whole number of similar bodies. It is possible a till nucleus may be 
somewhat common in these mammillary kames. 

The length of the system is about 11 miles. 


GENERAL NOTE ON THE BELFAST REGION. 


It will be seen that five gravel systems converge to Belfast Bay. The 
glacial scratches last made converge to the same place, while the earlier 
scratches were more nearly parallel. The discontinuous systems of gravel 
are, therefore, nearly parallel with the scratches last made, and they appear 
to date from the last part of the Glacial period. Most, perhaps all, of the 
discontinuous systems expand at some point into delta-plains, the largest of 
which are situated at or not far below the contour of 230 feet. Toward the 
south the gravel deposits become smaller and the intervals between them 
longer. 

The large island of Isleboro lies in the midst of Penobscot Bay, to 
the south and east of Belfast, and in the line of these systems prolonged. 
The island shows a limited amount of beach gravel, but no glacial gravel 
that I could find. Three of the Belfast Bay gravel systems come down to 
the shore, but their diminishing size toward the sea indicates that there was 
probably no large development of glacial gravel over what is now the sea. 


LOCAL ESKERS IN TROY AND PLYMOUTH. 


A broad, level region covered by marine clay extends from Unity 
Pond northeastward through Troy. It is continuous with a line of sedi- 


mentary clay extending northward through Plymouth and Detroit ‘to the 
MON XxxIv——10 


146 GLACIAL GRAVELS OF MAINE. 


Sebasticook River. Part, perhaps all, of these clays are marine, but the 
estuarine, fluviatile, and lacustrine drift are all present in that region and 
difficult to distinguish. On the slopes of rather low hills that border this 
clay-covered plain on the south and east are several local kames. One of 
these is situated in the southwestern part of Plymouth, at the southern end 
of a hill bordered on each side by a low north-and-south valley. It ends 
near the upper limit of the sedimentary clays. Two other deposits of 
glacial gravel are found in the north-and-south valley of a small brook 
flowing north into Carlton Stream. They are situated a short distance 
north of Troy Center. Still another is found on the east side of a north- 
and-south valley near Cooks Corner, about three-fourths of a mile west 
of Troy Center. It is a short terrace, only a few rods long, about 40 feet 
above the bottom of the valley and about midway up the slope. It has 
been cut through by the road to a depth of several feet. On the south 
side of the road the terrace is plamly stratified, the strata dipping down the 
hill and transversely to the ridge. The different layers vary much in com- 
position, some being fine sand, others coarse gravel and cobbles, slightly 
polished and rounded. Near the surface the mass is pellmell in structure. 
On the north side of the road, and only about 25 feet away, the whole 
section exposed shows the pellmell structure. The separate pebbles and 
cobbles are like those at the south side of the road in form, and the two 
sections differ in structure only. Both have plainly been water-assorted 
and the finer parts of the till have been washed away. It will be noted 
that the pellmell layer at the south overlies the stratified portion. Appa- 
rently a small kame was first deposited with a stratified structure, and 
subsequently the advance of the ice pushed the sediments forward sufti- 
ciently to mix up*the several layers near the surface and destroy the 
stratification. 

The hills extending from Palermo to Dixmont and Newburg rise 300 
to 600 feet above the broad plain-like valleys of the Sebasticook and 
Soudabscook, situated to the north of them. These hills would stop the 
flow of ice southward during the final melting of the great glacier long 
before the ice had disappeared in the lowlands to the north. As the ice 
gradually retreated northward, it would often happen that lakes would be 
inclosed between the ice and the hills to the south of them. Within the 
limited time these lakes were in existence no very large amount of sedi- 


‘ske|9 autre hq paiarod Ajjeau si Yd|YM ‘eSpli 1eso a4} MOjjo} edUa} pue peo! ay] 
‘LIONLSG ‘YvVSO 4O ONINSGNVAW 


XI Td AIXXX HdVYSONOW AZAYNS TVOISOIOAD *S “Nn 


GEORGES RIVER SYSTEM. 147 


ment could have been deposited, except where the larger glacial rivers 
flowed into them. It is possible that some of these lakes left too scanty 
sediment to be now recognizable. The glacial lakes of central Dixmont, 
as well as others to be hereafter named, also the short kames of Plymouth 
and Troy, seem to be connected phenomena, all pointing to the time when 
the ice front had retreated a short distance north of the hills. There was 
probably but little motion of the ice at this time. 

1. A still higher range of east-and-west hills lies only about 30 miles 
to the north of the Palermo-Dixmont Hills—those lying south of the Pis- 
eataquis River. These would cut off the southward flow of the ice nearly 
as soon as the lower hills to the south. henceforth there would be no 
pressure and supply of ice adequate to cause much advance of the ice even 
over so level a plain as the Sebasticook Valley. 

2. I have been able to find no very noticeable terminal moraines on the 
northern slopes of the Palermo-Dixmont Hills at the places where I have 
crossed them, though there are many irregular heaps of till, and these may 
yet be explained as the best approach to a terminal moraine which can be 
made by a mass of rather slow ice that is not receiving its moraine stuff on 
its surface, but from below, and is-gradually retreating. 

3. But that there was some motion is probably proved by the observa- 
tions at Cooks Corner, Troy, where we seem to have an instance of the ice 
advancing and obliterating the stratification of the surface portion of a 
kame.’ 

GEORGES RIVER SYSTEM. 


This is a discontinuous system of short ridges and lenticular hummocks. 
It begins about 3 miles south of North Searsmont. The gravel here is 
plainly water assorted, but the stones are only a little polished, retaining 
their till shapes except at the angles. This indicates that we are near the 
north end of the system. About 14 miles south of this is another short 
ridge; the next one is in the southwest part of Searsmont Village, and from 
this point the series lies near Georges River all the way to Thomaston. 
The gravels take the form of ridges one-third of a mile or less in. length, 
and they are more often mere elongated domes or mounds. The intervals 
are several times as long as the ridges, and are a constant feature of the 


‘For the facts near South Albion, see pages 165 to 167. 


148 GLACIAL GRAVELS OF MAINE. 


system from end to end. They vary from one-fourth mile to 1$ miles in 
length. The system seems to end in a cone or dome of glacial gravel sit- 
uated on the east side of Georges River, just above the railroad bridge at 
Thomaston. The gravel lies for most of the way on the west side of the 
river, and not far above it. The system lies in the towns of Searsmont, 
Appleton, Union, Warren, and Thomaston. 

Near Union Village a small mound of this series shows contorted and 
folded strata overlying stratified material. The dome lies so low in the 
narrow valley that it is very improbable an ice floe came from the north 
with sufficient force to distort the stratification. More probably the gravel 
was deposited beneath the glacier and the distortion was due to the pressure 
of the moving ice. This system is in a region once wholly covered by the 
sea, unless on the extreme north. 

The length is about 8 miles. 


HARTLAND-MONTVILLE SYSTEM. 


A series of rather short ridges begins near the top of a high range of 
hills in the northern part of St. Albans. It extends southward past Indian 
Pond and through St. Albans Village, and thence southwestward along a 
branch of the Sebasticook River. A short distance south of Hartland Vil- 
lage this series unites with another, which takes the form of a large ridge 
beginning at the south shore of Moose Pond and thence taking a south- 
ern course through Hartland Village. The gravel of the latter series is 
much rounder than that of the St. Albans series, which is but little worn. 
This indicates that the Moose Pond system probably has a northward exten- 
sion. The Cambridge-Harmony eskers hereafter to be described would 
naturally be a part of this system, but thus far I can not prove a connec- 
tion. From Hartland the united series continues south as a quite continu- 
ous osar ridge for several miles. In the southern part of Pittsfield the 
system is interrupted at several places. About one-half mile north of Pitts- 
field it rises into a rather high cone called the ‘“Pinnacle.” From this point 
southward through Pittsfield, Burnham, and Unity the gravel takes the form 
of a nearly continuous osar with very gentle lateral slopes. It rises 10 to 
30 feet above the marine clay which borders and partly covers it. In 
places the ridge is nearly one-eighth of a mile broad, yet it is rounded on 


HARTLAND-MONTVILLE SYSTEM. 149 


the top, so that its cross section is almost always arched. At Peltoma Point 
the ridge crosses the Sebasticook River. The river can be forded on the top 
of the ridge, but the water is much deeper on each side. It also rises 
nearly to the surface while crossing Unity Pond. The ridge broadens 
south of Unity Pond, and from near Unity Village a plain of complicated 
structure extends south along the valley of Sandy Stream almost to Thorn- 
dike station. ‘The plain fills the valley from side to side, and is from one- 
fourth to one-half of a mile wide. It shows some arched ridges of gravel, 
bordered and often covered by a more nearly horizontally stratified stra- 


Fic. 16.—Osar; Pittsfield. 


tum of fine gravel, sand, and clay. Originally there were kettleholes, but 
most of them have been filled or nearly filled by the later sediments. The 
sea certainly extended to Unity, as is proved by marine fossils. How far 
it extended up the valley of Sandy Stream is uncertain. The contour of 
230 feet would be found 1 or 2 miles south of Unity Village. The origin 
of this plain will be discussed more fully later. 

Not far from the junction of Sandy Stream with Half Moon Stream 
the gravel comes up out of the valley. For a half mile southward it takes 
the form of a broad osar, or perhaps delta-plain. Then for several miles it 


150 GLACIAL GRAVELS OF MAINE. 


is a two-sided ridge, or often a terrace on the hillside west of Half Moon 
Stream and 50 feet or more aboye the stream. It skirts the eastern slopes 
of a high hill im Unity and Knox, and near Chandlers Corner crosses the 
north branch of Half Moon Stream, and within one-eighth of a mile 
disappears as a two-sided ridge. Here it required careful observation to 
determine the course of the glacial river, and the result was quite unex- 
pected. The ridge seems to be lost at the northern base of a range of hills 
300 to 500 feet high. This range is several miles in length and has a 
northeast-and-southwest direction. Along its northern base is a depression, 
or valley, occupied by the south branch of Half Moon Stream, which flows 
northeastward. It is from 100 to 400 feet wide and from 20 to 40 feet 
deep. In places nothing but till can be seen in the steep banks inclos- 
ing it, and it looks like a large canal cut in a deep sheet of till. In other 
places there is a steep wall or cliff of solid rock 10 to 30 feet high, gla- 
ciated on the top, bordering the valley on the north, and it is thus proved 
to be, in part at least, a valley of preglacial weathering and erosion. It is 
parallel with the strike of the upturned pyritiferous and other easily weath- 
ered slates and schists characteristic of this region. The depression, being 
transverse to the direction of general glacial movement, became more or 
less filled with till. The bottom of this valley is covered by a level-topped 
plain of sand and well-rounded gravel 10 to 20 or more feet in thickness 
and 1 to 400 feet wide. The south branch of the Half Moon Stream flows 
in this valley for about 2 miles, but it is a small brook, such as ordinarily 
has in that region a flood plain containing only 1 to 3 feet of gravel, the 
stones of which have the till shapes almost unchanged. Plainly it is incom- 
petent to deposit any such plain of sand and rounded gravel as that found 
in its valley. At one place the brook soaks into the gravel and disappears 
except in time of flood, when it can not seep into the gravel as fast as the 
flow from above, and the surplus water then for a time escapes by an over- 
flow channel over a rough and crooked bed evidently recently eroded in 
the till and gravel. As this channel is dry most of the time, it is locally 
known as the ‘Dry Stream.” The water which disappears in the gravel, 
as above described, comes out again about one-fourth of a mile below in 
the form of boiling springs, which are eroding the gravel more rapidly, 
working from beneath, than both the main stream and the overflow stream 
combined are eroding it above where the water disappears in the gravel. 
In this way the gravel plain has been eroded for more than one-fourth of a 


HARTLAND-MONTVILLE SYSTEM. 151 


mile from where we lost the osar as a two-sided ridge. It is evident that 
the valley is filled by a rather narrow osar-plain. It extends continuously 


Zs, 
Zz 


ZI 


Aa 
KS 
AS 
AS 


Fig. 17.—_Map of Hoghack Mountain; Montville and vicinity. 


for about 1 mile and then is interrupted by two or three gaps of one-third 
mile each or thereabout. In places the erosion has revealed arched ridges 


152 GLACIAL GRAVELS OF MAINE. 


of coarser gravel, which were afterwards covered by at least 15 feet of fine 
gravel, and finally sand and clay, more nearly horizontally stratified and 
extending across the valley before mentioned. This remarkable depression 
is bordered much of the way by a steep bank of till, especially on the 
north. It extends for about 3 miles along the base of the high hills, when 
it comes out to a very low north-and-south pass through the range. To the 
west of this pass rises Hogback Mountain, and I will term it the Hogback 
Mountain Pass. Fora short distance east of this pass the bottom of the 
U-shaped valley containing the osar-plain is rather stony, then for one- 
fourth mile or more there is a curious narrow bog, occupying the northern 
part of the valley, while on the south side is a level terrace, apparently 
composed of till. This terrace is several feet higher than the bog. A 
cross section of the valley at this point is shown in fig. 18. 

This part of the valley is bordered by a bluff of till 20 to 25 feet high. 
It is as steep as the banks of most streams, and shows every mark of an 
erosion cliff. In this part 
of the valley only very 
local drainage takes place, 
since even the little south 
branch of the Half Moon 


Fic. 18.—Section across channel eroded in the till; Montville. a, bog in 


Gisnamnell av comession, Stream enters the valley 
to the east of this point. These facts establish the following conclusions: 
The osar river came to the northern base of the high hills and turned 


southwest along a small previously existing valley. This valley consisted 
of a valley in the rock which had become deeply filled by till. The stream 
flowing in the valley eroded the till to a considerable depth, leaving its 
channel bordered by cliffs of erosion. The narrow bog above described 
was once an erosion channel deeper than the rest of the glacial channel. 
Originally it formed a small lake, but by degrees has become peated 
over. As the velocity of the osar river diminished during the final melting, 
the osar-plain was deposited im the lower part of the channels, though 
near the highest point of the region crossed but little if any gravel was 
deposited. 

At the north end of Hogback Mountain Pass the system we have been 
tracing from Hartland and St. Albans is joined by a tributary branch, which 
begins near Freedom Village. It follows a low pass southward, over a hill 
about 100 feet high, where its course is bordered by a bluff of till so steep 


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HARTLAND-MONTVILLE SYSTEM. 153 


as to suggest that it has been eroded, then passes Halldale and soon crosses 
the valley of the south branch of Half Moon Stream. Here it expands 
into a plexus of reticulated ridges near one-fourth mile wide and 1 mile 
long. Thus, at their junction these two glacial rivers must have behaved 
very differently. The long Hartland glacial river swept everything 
before it and eroded a deep channel in the till, while the shorter Free- 
dom River deposited a very large amount of sediment. For some reason 
the waters of this river were slowed down as they came to the level 
ground north of the junction of the two glacial rivers, though they must 


Fic. 19.—Reticulated ridges and Hogback Mountain, from the north. 


have been swift to the north of this place in order to have swept down 
so much gravel, much of it containing cobbles and bowlderets. South of 
their junction I have not been able to distinguish the gravels of the two 
streams. 

A series of broad and somewhat reticulated ridges, inclosing kettle- 
holes and large basins containing peat swamps, extends southward through 
the Hogback Mountain Pass. he roadbed occasionally sinks into the 
peat of one of these swamps. The pass is somewhat more than a mile 
long and less than a fourth as broad. At the south end of the pass a 
short hillside esker comes down the slopes of the hill lying on the east 
side of the pass and joins the main system in the valley. The gravels 


154 GLACIAL GRAVELS OF MAINE. 


at the south end of the pass present some very interesting developments. 
The east branch of Georges River (or St. Georges River, as it is named 
on many maps) rises in the hills east of Hogback Mountain. It flows 
westward to the south end of the Hogback Mountain Pass, and then 
south and east through Montville and Searsmont. A plain of gravel 
bowlderets and bowlders (all well rounded) extends from the south end 
of the pass for a half mile down the valley. The material is coarse 
even to the margins of the plain. Southward in this valley the glacial 
gravel is scanty and discontinuous for about 2 miles on a down slope of 
20 to 40 feet per mile, yet at intervals it is found in small masses. It forms 
a small terrace on the western side of this stream at Center Montville, 
and, becoming more abundant toward the south, soon spreads out into 
a rather level plain 25 miles long and more than 1 mile wide. This is 
situated not far northwest of North Searsmont. Toward the south the 
gravel of this plain passes into sand, and this again into clay, which 
extends continuously down the valley of Georges River to the sea. This 
is evidently a marine delta, and seems to terminate the gravel system 
in that direction. 

We now return to the plain of coarse glacial gravel at the south end 
of Hogback Mountain Pass. This deposit is somewhat triangular in shape. 
One apex is at the south end of the pass, another extends down the valley 
of the east branch of Georges River, while the third lies in a depression 
along the southern base of Hogback Mountain, about one-half mile south- 
west of the first. From the last-named point a narrow plain of glacial 
gravel and cobbles extends for a short distance southwest along the base 
of the “‘mountain.” The Muskingum Stream drains the area south of Hog- 
back Mountain and joins the west branch of Georges River near South 
Montville. It has several tributaries, the largest two of which I will call 
the east and west branches. We have seen that the osar river followed the 
base of the mountain southwest for a time. By turning to the south and 
crossing a col only 20 or 30 feet high, it might have flowed south along the 
east branch of the Muskingum Stream. It actually rejected this pass, and 
about one-third of a mile farther west turned southward along the valley of 
the west branch of Muskingum Stream. Within 3 miles it left this valley 
and went obliquely southwestward over a low divide into the valley of the 
east branch of the Muskingum Stream, the same valley it could so much 


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HARTLAND-MONTVILLE SYSTEM. 155 


more easily have entered at the southern base of Hoeback Mountain. On the 
down slopes in this part of its course the system is somewhat discontinuous. 
Near where the system enters the valley of the east branch of the Muskin- 
gum Stream it expands into a plain of reticulated ridges, with an outlying 
bar directed toward the southwest, but I could find no prolongation of 
the system in that direction. Just north of this plain lies a narrow, almost 
V-shaped, valley, bordered by rather steep cliffs of till. No ordinary stream 
flows in the valley, except the merest brook, and the appearances are as if 
the glacial river had here eroded the till. The gravel system here turns 
east and crosses the road leading up the valley of the east branch, and then 
becomes a prominent feature of the valley southward to the settlement in 
Montville known as the “‘Kingdom,” being alternately on the east and west 
sides of the road. The gravel appears like a rather level terrace at the side 
of the stream, but there is no corresponding terrace on the east side of the 
valley. Well-rounded bowlderets and bowlders abound in the gravel and 
at once betray the glacial origin of the deposit. Near the “Kingdom” the 
eravel expands into a large plain—the Liberty Plains—which nearly fills 
the broad level valley, in the midst of which lies Trues Pond. One tongue 
or expansion of these plains reaches from: near Liberty Village southeast- 
ward almost to South Montville, but the principal expansion is south and 
west, and this seems again to divide into two parallel plains inclosing 
between them Stevens Pond and then continuing on southwestward through 
Liberty into Appleton. Near the “Kingdom” and Liberty Village these 
plains consist of broad reticulated ridges of very coarse matter, inclosmg 
kettleholes and even lake basins. Southeast toward South Montville they 
become rather level on the top and finer in composition, while the long 
narrow plains which extend southwestward into Appleton show very clearly 
the transition from coarse sediments on the north to fine on the south, char- 
acteristic of the delta. On the south these sand plains pass by degrees 
into sedimentary clay, which extends all the way down the Medomac Val- 
ley to the sea. The more level portions of the gravel-and-sand plains of 
Liberty and Appleton are thus proved to be marine delta-plams. In the 
narrow valley of the west branch of Georges River at South Montville no 
sand or gravel appears for about one-fourth of a mile. Then begins a delta- 
plain extending about one-half mile eastward toward Searsmont, and then 
sending out a long tongue southwestward for about 3 miles into Appleton. 


156 GLACIAL GRAVELS OF MAINE. 


I find no signs of any glacial streams that could have deposited the last- 
named plain except that delta branch of the Hartland system which radiated 


? 


southeast from the ‘‘Kingdom;” neither could I trace this system farther 


south than the delta-plains in northern Appleton. 
SUMMARY. 


The Hartland-Montville osar river must have deposited its gravels late 
in the osar period, or, like the Katahdin and other osars, it would have 
deposited gravels all the way to the sea. At this time the sea stood at or 
near the contour of 230 feet, and the delta-plains of Liberty and Appleton 
do not extend much below that elevation. In the Sebasticook Valley, for 
about 20 miles, from Hartland to Unity, the system traverses a region that 
was at one time submerged in the sea, as is proved without a shadow of 
doubt by the great numbers of marine fossils found in the sedimentary 
clays which partly or wholly overlie the glacial gravel. But at the time 
when the delta-plains in Liberty, Appleton, Searsmont, and Montville were 
being laid down, the Sebasticook Valley must have been covered by ice, as 
is proved by the great size of the glacial streams by which only could so 
large plains be deposited. The glacial waters of the Sebasticook recion 
then poured southward through the Hogback Mountain Pass over a divide 
not far from 200 feet above the level of the osar at Unity Pond. Into the 
north end of this pass two glacial rivers flowed from the north, one from 
Unity and Hartland, the other from Freedom. At the south end of the 
pass the system received another tributary, while from the enlarged chan- 
nel or glacial lake at that point two delta branches diverged, one flowing 
south and the other southwest, and they emptied into the sea at points 
about 10 miles distant from each other. The narrow delta-plains in Liberty 
and Appleton are in a level region, where, if the glacial river had flowed 
into the open sea, they ought to have spread out in fan shape. That. they - 
remained so long and narrow is an indication that they were not deposited 
in the open sea, but in bays of the sea which extended back into the ice. 
The question whether a stratum of floating ice was over these plains will 
be considered elsewhere. he plain northwest of North Searsmont is more 
broadly fan-shaped. Its northern end extends across the valley of Georges 
River, and the delta was probably deposited in the open sea. 

Did the two glacial rivers, which diverged from the south end of the 


HARTLAND-MONTVILLE SYSTEM. 157 


Hogback Mountain Pass, flow simultaneously? I was unable to find any 
conclusive facts in the field. Two reasons can be given why it is probable 
that the Liberty branch was the earlier. 

1. The delta-plains of this system seem to date from a time when the 
ice had not receded so far north as at the time'the North Searsmont Plain 
was being deposited. 2. The glacial stream which formed the last-named 
plain flowed not only down a valley of natural drainage, but parallel with 
the direction of glacial flow. The gravel, too, is scanty for some distance 
on the steep down slopes, so that the glacial channels did not there become 
clogged with sediment. I see no reason why this stream should cease to 
flow, or why, after it once had been established, it should not carry away 
all the water that poured southward through the pass. On the other hand, 
the southwestern channel was over higher ground, and for a time was trans- 
verse to the lines of flow of the ice. At any time the south channel should 
be opened this stream would cease to flow, except possibly when the water 
was very high. The history of the gravel plain at the south end of the 
pass is probably about as follows: Originally the glacial river flowed by 
the southwestern channel and solid ice blocked the valley of the east 
branch of Georges River. Then a lake was formed within the ice at the 
south end of the pass, in which was deposited the coarse matter of the 
plain, or a part of it. The lake gradually enlarged, so as finally to extend 
for one-fourth mile or more eastward into the valley of the east branch of 
Georges River, which, as already stated, extends eastward from the south 
end of the Hogback Mountain Pass. In this enlarged lake was deposited 
the thick sheet of sedimentary clay and silt which covers this valley to the 
east of the pass. Finally the barrier of ice in the valley was in some way 
penetrated toward the south and a new channel was established down the 
valley to Center Montville and to the sea near North Searsmont. This 
channel would naturally come to be lower than the other, so that it would 
carry off all the water of the glacial lake, except in times of great floods, 
when the southwestern channel might still, for a time, serve as an overflow 
channel. In process of time the south channel would become enlarged so 
as to take off all the water by the lowest route. All the field phenomena 
could be produced by two streams flowing simultaneously. But. much the 
larger stream flowed southwest, and it deposited far more gravel than the 
other. These facts favor the conclusion that it flowed much longer than 


158 GLACIAL GRAVELS OF MAINE. 


the other stream. If the two channels were formed simultaneously, I can 
conceive no reason why the south channel on a down slope should not 
enlarge as fast as the southwestern channel on an up slope. If they enlarged 
with equal rapidity, the larger amount of sediment ought to have been 
deposited by the eastern imstead of the western stream. These facts all 
combine to justify the conclusion that the diverging delta streams were for 
most of the osar period not simultaneous, but that the Liberty branch was 
the earlier. 

During the final melting there must have come a time when the thin- 
ning ice could no longer flow southward over the hills and when the supply 
of glacial water from the north would be diminished. The glacial river 
flowed sluggishly, and presently in the osar channel northeast of the north 
end of Hogback Mountain Pass there was deposited an osar-plain of fine 
gravel and sand, and finally clay. As the ice continued to melt, the ice 
front began to retreat northward from the hills, and there came a time when 
a lake occupied the valley of Half Moon Stream. This valley is widely 
covered by a sheet of sedimentary clay to a height of at least 260 feet 
above the sea. The small Half Moon Stream could not have deposited 
this clay as ordinary valley alluvium, for it reaches at least 30 feet above 
the stream. The most probable interpretation is that in Thorndike, Knox, 
and Unity there was a glacial lake several miles long confined between the 
ice on the north and the hills on the south, east, and west. It may not 
have always stood at the same height. For a time this lake may have 
overflowed south through Hogback Mountain Pass. Into the lake still 
poured a supply of glacial water from the north, and in it was deposited 
the delta-plain situated between Unity and Thorndike which overlies the 
ridges previously deposited in narrow ice channels in the midst of the 
valley of Sandy Stream. This delta reaches from near Unity Village 
almost to Thorndike station. But in the meantime the sea had been 
advancing up the valleys of the Kennebec and thence eastward over the 
broad valley of the Sebasticook River. If it first advanced along the south 
side of the high hills which border the Sebasticook Plain on the south, 
then it might be that the extreme northern part of the delta-plain south of 
Unity Village was deposited in the sea. With possibly this exception, the 
advance of the sea was so simultaneous over the Sebasticook Plain that no 
marine deltas were formed by this glacial river in that part of the State, 


CAMBRIDGE-HARMONY GRAVELS. 159 


unless the plam in Cambridge and Harmony, soon to be described, was 
formed by a remnant of this glacial river which still continued to flow 
after the ice in the main Sebasticook Valley had disappeared but while the 
ice still lingered north of Moose Pond 

The length of the system is 45 miles. 


CAMBRIDGE-HARMONY GRAVELS. 


A series of low sand-and-gravel ridges, or narrow plains, extends from 
near Main Stream in Cambridge northward past Cambridge Village and 
then for 2 or 3 miles into the southwestern part of Parkman. The stones 
are barely rounded on the angles, and in general the gravel is fine. On the 
south the series spreads out into a sand plain in the Main Stream Valley. 
This plain appears to have been deposited in the valley after the ice had 
there melted, though still remaining northward; yet the sand may have 
been laid down in a glacial lake. The currents which assorted these sedi- 
ments were rather gentle, and probably the formation dates from a very late 
portion of the Glacial period. 

Another ridge is found near the line between Harmony and Cambridge, 
ending in the south near the northern shore of a large pond above Main 
Stream Village. Toward the south the material becomes fine, consisting of 
sedimentary clay overlying fine sand. 

A short gravel deposit is found near Main Stream about a half mile 
south of Main Stream Village. 

A gravel plain, probably glacial, is found in the south part of Har- 
mony, in the valley of a small stream. It resembles an osar-plain. It is 
possible that this extends northward past Harmony Village. I have note 
of sand and clay in the valley of the Sebasticook above Harmony, and they 
may be of glacial origin in part. 

Probably a large area in Cambridge, Parkman, Wellington, and Har- 
mony was at one time drained of its glacial waters by the large glacial river 
which flowed from Moose Pond south past Hartland. But if so, the proof is 
not easily derived from the distribution of the gravels. The gravels in 
this region seem to date from a late period, when the ice had retreated 
north of Moose Pond, and the glacial streams were in fact soon discharged 
beyond the ice front into the open valleys. 


160 GLACIAL GRAVELS OF MAINE. 


PALERMO-WARREN SYSTEM. 


This system begins in Palermo near where the towns of Palermo, 
Freedom, and Montville join. Here a north-and-south ridge of till becomes 
more stony toward the south, and by degrees passes into unmistakable ¢la- 
cial gravel within one-fourth of a mile. The fact that the glacial gravel 
consists of the till with the finer detritus washed out of it is here well 
exhibited. Near the east branch of the Sheepscot River this ridge turns 
southwestward, and follows the valley for several miles. This stream flows 
along the northern base of the high northeast-and-southwest range of which 
Hogback Mountain in Montville is a part. Much of the way along the 
valley the gravel is in the form of a ridge, but it becomes terrace-like and 
somewhat discontinuous as it approaches Sheepscot Great Pond. This 
pond lies in the midst of a cirque 5 miles in diameter. This broad, rather. 
level valley is surrounded on all sides by rather high hills except at a few 
narrow passes. The lowest depression is southwest down the valley of the 
east branch of the Sheepscot River, but the glacial waters rejected the valley 
of natural dramage and took a course over higher ground to the south and 
southeast. ‘Two lines of glacial gravel extend from Sheepscot Great Pond 
southward. For 2 or 3 miles they are nearly parallel and only from one- 
fourth to one-half mile apart. The western series takes the form of an osar- 
plain one-eighth to one-fourth mile wide. It penetrates a low pass along 
the western base of the high granite peak called Patrick Mountain, and 
continues as an osar-plain till it nears Jones Corner, on the road from 
Somerville to South Liberty. Here it takes the form of a two-sided ridge 
of arched cross section for about 1 mile. In this part of its course it tums 
east by a rather abrupt curve and then closely skirts the southern base of 
Patrick Mountain. In so doing it crosses a hill about 75 feet high, the 
gravel disappearing for one-third of a mile on the up slope. Near the top 
of this hill it takes the form of an osar-plain for a short half mile, and then, 
on a steep down slope, there is no gravel for near 1 mile to Branch Stream, 
which flows south into Damariscotta Great Pond at East Jefferson. 

We now go back to the swampy plain south of Sheepscot Great Pond 
in the midst of the remarkable Palermo basin, where the two lines of glacial 
gravel are found side by side. The more eastern of the two formations has 
the form of a broad osar, with arched cross section. It soon diverges from 


PALERMO-WARREN SYSTEM. 161 


the western series and takes a southeast course through ‘The Gore,” a por- 
tion of land unattached to any town, and passes around the northeastern 
base of Patrick Mountain. In so doing it goes up and over a hill 100 feet 
high, and then descends into the valley of Branch Stream, where it turns 
southward and soon unites with the series which diverged from it near 
Sheepscot Great Pond to go around the western base of Patrick Mountain. 
Except on the steep down slopes and one gap on an up slope, the gravels 
are continuous along the courses here indicated. The material is in general 
rather coarse, many cobbles, bowlderets, and some bowlders being mixed 
with the sand and gravel. The stones are all very round, an indication that 
they are part of a long system, not of a local one. The field proof is 
positive that these large glacial rivers diverged from each other so as to go 
around opposite sides of a high hill and then came together. In both cases 
we find little or no gravel on down slopes of from 50 to 100 feet per mile, 
but it is certain the glacial streams came from the north to the top of the 
hills, and must have flowed down them; and at the base of the hills the 
gravel begins again. It is a fair inference that on the steep slopes the 
glacial streams were so rapid as to deposit little, if any, sediment. 

From where the two glacial rivers united, in the valley of Branch 
Stream, a nearly continuous osar-plain extends southward near the stream 
for a few miles, when the gravel leaves this stream and takes a course south- 
eastward, soon expanding into a large, somewhat fan-shaped plain, situated 
not far southwest of Newhalls Corner, in Washington. This plain consists, 
toward the north, of broad reticulated ridges inclosing shallow hollows. 
The material here is coarse. Toward the south the plain becomes quite 
level and the gravel passes into sand and finally into the marine clay. It 
is 24 miles long and more than a mile wide. It is plainly a marine delta, 
and its shape is such as to make it probable that it was deposited in the 
open sea, possibly in a very broad bay of the ice. Its outlet has cut down 
a channel 100 or more feet wide to a depth of about 4 feet, and numbers of 
ordinary till bowlders are exposed where the gravel has been removed. 
The little polishing they may have received from the gravel has been 
obliterated by weathering. The same thing is observed over a considerable 
area, and proves conclusively that the glacial gravel and sand overlie the 
till and are without admixture of till; hence they were deposited after the 


melting of the ice at this place. The outlet of the lake above described 
MON xxxIv——11 : 


162 GLACIAL GRAVELS OF MAINE. 


flows southward. In the southeast part of the plain the gravel is deeper 
and has been eroded considerably by boiling sprmgs. A ravine 10 feet 
deep has been eroded back into the plain for one-fourth of a mile or more. 
In many places this delta-plain is overlain to the depth of 1 to 3 feet with 
marine clay. From this point southward the system is discontinuous and 
consists of short ridges, lenticular mounds, and round-topped plains, except 
a delta-plain at its south end. The gravels are separated by intervals of | 
from one-eighth to one-half of a mile, generally the shorter distance. It is 
specially noticeable in case of the southern part of this system that the 
gravels appear on the tops of low hills or at the brow of broad hills, while 
the lowlands show little or no gravel. The series crosses Medomac Pond, 
and thence its course is easily followed along the road from North Waldo- 
boro to Warren. At the western edge of the valley of the Warren ponds 
the system divides into two series. One crosses to the east side of the 
valley at once, the other follows the eastern brow of the hills which border 
this valley on the west. In a mile or two this series also crosses to the east 
side of the valley, and then takes a course nearly parallel with the other 
series. They pass southward, and not far southeast of Warren station they 
end in sand plains. For the last mile or two they are quite continuous and 
form plains one-eighth to one-fourth mile wide,'and hence resemble the 
parallel plains of Liberty and Appleton. Their shapes and their situation 
on the tops of hills prove that they were deposited within ice walls, or the 
gravel would have spread out into broad fan-shaped plains. The discon- 
tinuous portion of this system—that part where gaps form a constant 
feature of the system, not an occasional gap on a steep down slope—is 
noticeable for the large amount of gravel which it contains, the lenticular 
plains which cap the hills being larger than the average. In the valley of 
Georges River and the Medomac above Waldoboro the gravels are in or 
near the lowest parts of the valley. But in general this system seems to 
delight in the highest ground that lies in its course, leaving the low valleys 
for the gaps. 

Two or three short tributaries entered the main glacial river near 
Sheepscot Great Pond. They drained the large Palermo cirque. Their 
gravels are but little water polished, and they are evidently only short 
branches of the main system. 

Length from Palermo to Warren, 23 iiles. 


MEDOMAC VALLEY SYSTEM. 163 


SHORT ESKERS IN WALDOBORO. 


Two small and rather level plains of sand and gravel are found a 
short distance south of the terminal moraine in Waldoboro, elsewhere 
described, one on the road from Waldoboro to North Waldoboro, the 
other about half a mile east of this on the road to Union. Both seem 
to be small marine delta-plains. Their north ends lie a short distance 
south of the terminal moraine, but thus far I can not connect them with 
this moraine in a genetic way. The marine clay covers the deposits on 
the flanks and makes it difficult to trace the connections of these sands. 


MEDOMAC VALLEY SYSTEM. 


This system begins in the valley of the Medomac River about 2 
miles north of Winslows Mills, and extends southward to Waldoboro 
Village. For most of this distance its course is near the stream in the 
lower part of the valley. he series consists of short ridges and elongated 
mounds, or sometimes more nearly cones, separated by intervals of one- 
eighth to one-third of a mile, and is discontinuous from one end to the 
other. None of the deposits are more than about 20 feet high, and many 
of them are much lower. They are often covered wholly or in part by 
the marine clay. Toward the north end of the series the gravel is but 
little waterworn, and at the last can hardly be distinguished from a sandy 
till. The relations of this gravel system to the terminal moraine at 
Winslows Mills will be referred to hereafter. 

Length, about 5 miles. 


LOCAL GRAVELS IN NOBLEBORO AND JEFFERSON. 


A gravel ridge comes from the north and enters the so-called Great 
Bay at East Jefferson. It can readily be traced northward up a hill for 
about a mile, where it seems to end in a low pass. To the north of this 
pass, in the northern part of Jefferson, is a short ridge of subangular glacial 
gravel, but I could trace no evident connections southward. Gravels are 
reported at various points along the Damariscotta Great Pond, but I am 
uncertain whether they are old beaches or not. Near Muscongus Bay 
station of the Maine Central Railroad is a small plain of glacial gravel. 
Another appears about one-fourth of a mile farther south, and a third 


164 GLACIAL GRAVELS OF MAINE. 


within a mile farther, near Nobleboro Post-Office. The three gravel plains 
south of Muscongus Bay have a linear arrangement; probably they all are 
deltas, and they may have been deposited by the same glacial stream. 
Whether they are connected with the East Jefferson gravels is uncertain. 
Two other small gravel plains are found in Nobleboro north of Duckpuddle 
Pond. A small ridge of glacial gravel is found near the west shore ot 
Damariscotta Great Pond, about 3 miles north of the south line of Jeffer- 
son; and 3 miles farther north another small ridge is found on an east-and- 
west road. All of these local gravels are found in a region that was under 
the sea. Old beaches abound in the same region, and it requires some care 
to distinguish the glacial from the beach gravel. 


DYERS RIVER SYSTEM. 


A very discontinuous system seems to begin in Jefferson, west of 
Dyers Long Pond, and extends southward about 4 miles along the valley 
of Dyers River. It then passes obliquely out of the valley, southeastward 
into a rolling plain near 100 feet above the stream, and appears to end near 
Great Meadow River in Neweastle. So far the system is pretty well 
defined. About 2 miles from the north end of the system, as above 
described, are two short gravel ridges, and a mile farther north, at West 
Jefferson, is a gravel-and-sand plain one-half mile long and a full eighth 
of a mile wide. This is probably a marine or lake delta. A trotting track 
has been made on it. One mile northwest of West Jefferson are two short 
but good-sized ridges, and 2 miles north of them are two small ridges, in 
the valley of the west branch of the Sheepscot River. Two miles farther 
north is a small gravel deposit, near Coombs’s store in Windsor. All of 
these last-named gravel deposits have a linear arrangement and are situated 
along a route level enough for the passage of a glacial river without its 
having to cross hills higher than about 100 feet, but the gaps between the 
gravels are so long and the deposits so small that it is uncertain whether 
they were deposited by the same glacial stream. Most of the deposits of 
Dyers River system, as well as the very widely separated gravels north of 
them, are situated on the tops of hills, or on their flanks, 50 or more feet | 
above the adjacent valleys. The gravel is all pretty well rounded. 

Its length is 12 miles. 


SYSTEMS OF GLACIAL GRAVELS. 165 


SOUTH ALBION-CHINA SYSTEM. 


About 2 miles east of South Albion (Puddledock), at the northern 
base of the high hills which border the Sebasticook Plain on the south, is 
a plain one-fourth mile long and more than half as wide. It contains 
many well-rounded bowlderets and bowlders 2 to 3 feet in diameter. On 
all sides it ends in a bluff 20 to 30 feet high. To the north is the gently 
rolling plain of the Sebasticook Valley, covered for many miles with 
marine clays. I could find no similar deposits to the north or east of this 
plain. A series of similar broad level-topped plains, separated by short 
intervals, extends southwest of this point along the northern base of the 
hills, at a height of 50 to 75 feet above the clay plain. Some of these 
plains are bordered on both sides by steep banks; others were deposited 
against the side of the Ill as terraces. These plains present a curious 
alternation of areas of coarse gravel, containing bowlderets and bowlders, 
with areas of sand, as if these were a series of deltas deposited in broad 
channels in the ice which were practically glacial lakes. The terraces 
become narrow near South Albion. From this point for several miles they 
are in a harrow valley in which a branch of Fifteenmile River flows north- 
east to South Albion. Usually the gravei takes the form of terraces on 
the east side of this valley, while one-fourth of a mile distant on the oppo- 
site side of the valley, or often less than half that distance, are a large 
number of morainal heaps and ridges. In several places the appearances 
are as if a glacial stream flowed through the valley while the ice was still 
thick. Then later a narrow and thinner tongue of ice, practically a local 
glacier, lingered for a time in the valley, and at this time the glacial river 
assorted the moraine stuff that was cast down on the east side of the valley, 
while on the west side the lateral moraine retained its pellmell structure. 
These heaps of till may be in part the termmal moraines of the hypotheti- 
cal local glacier formed during its retreat northward. If these peculiar 
masses of till are not due to a local movement, as suggested, they are a 
strange freak of the general movement. 

In the southwestern part of Albion the system crosses a very low divide 
and continues straight on through China to the northeastern base of Par- 
menter Hill. It here turns abruptly westward and skirts the north and 
west bases of this high hill, taking the form of a narrow plexus of two or 


166 ‘ GLACIAL GRAVELS OF MAINE. 


three ridges inclosing numerous kettleholes and one or two lake basins. 
The ridges become broader toward the south and coalesce into a level plain 
of sand, which ends near the road from Branch Mills to China Village. 
Within a short distance the gravels begin again and continue in a nearly 
straight line southwestward, ending about one-fourth of a mile south of 
Weeks Mills, in the southeastern part of China. For several miles the 
gravels are in the form of a long plain one-fourth mile or less in breadth. 
Near Weeks Mills the plam consists of one or more ridges of arched cross 
section, flanked and sometimes covered by fine gravel and sand, and the 
plain is bordered by sedimentary clay, which extends down the Sheepscot 
Valley to the coast. 

The structure of the plain indicates that a ridge was first formed in a 
narrow channel within the ice. Subsequently a marine or estuarine delta- 
plain was deposited in a broad channel open to the sea to the south, but 
still confined between ice walls at the sides. In some respects this delta- 
plain resembles the osar-plain in its form and relations to the central ridge, 
but in this case the original ridge was less modified than is usually the case 
in the osar-plain, so that the distinction between it and the bordering plain 
is quite sharply defined. 

This system is remarkable for its large size at the extreme north end. 
This indicates a northward extension of the system, but I have not been able 
to find any. The country is so deeply covered by the marine clay that large 
gravel ridges might exist beneath the clay and not attract attention. Sev- 
eral ridges and mounds, probably of glacial gravel, are found near the east 
base of Parmenter Hill, and they may be a connection of this system. 

The large size of the bowlders contained in the gravel plains at the 
north end of this system, together with their topographical relations, suggest 
that they were formed at the front of a mass of moving ice. Several other 
facts support the same conclusion: 

1. This glacial river formed a marine delta in the southern part of 
China, 40 miles or more from tide water, at an elevation of about 200 feet, 
and there is no proof that it at any time flowed farther south. It must 
have been pretty late in glacial time when the ice had melted so far north 
as this. 

2. As before noted, the ice could no longer flow south over the hills 


SOUTH ALBION-CHINA SYSTEM. 167 


which extend nearly east and west from Albion and Palermo to Newburg 
after it became less than 500 or 800 feet thick. About the same time that 
the flow was arrested here it would be arrested by another east-and-west 
line of hills situated about 30 miles farther north (those lying south of 
the Piscataquis Valley). The broad level valley of the Sebasticook would 
be filled by a sheet of ice sloping south, and it would for a time send out 
projecting tongues over the lower cols. One of the lowest of these passes 
is that which is followed by the South Albion-China system of gravels. 

3. Since at this time the melting waters could escape only by the low 
passes, they collected near the hills and then flowed east or west till they 
found an exit. This water, being exposed to the sunlight, would melt the 
ice rapidly near the base of the hills which lay as a barrier to the south, 
and thus considerable sized pools or channels might be formed. The glacial 
streams from the north would flow into these, and at the same time there 
was a limited flow from the north of the ice. Thus the matter brought 
down by the glacial streams would be mixed with matter brought to the 
edge of the pool by the moving ice and subsequently dumped into the pool 
by the melting of the ice that held it. On this hypothesis the plains which 
lie along the nofthern bases of the hills near South Albion are a mixture of 
water-washed moraine and ordinary kame matter. 

The local conditions at South Albion certainly favor a flow of ice to 
this poimt until very nearly all the ice was melted. The valley of Fifteen- 
mile River narrows toward the southwest so as to converge the movements 
into the narrow pass. A very small motion of the separate particles of ice 
over the broad plain stretching 30 miles northward would cause a con- 
siderable movement in the narrow valley. The ice there, being crowded 
against the hills, would not form a glacial lake extending from the hills 
back to a considerable distance northward. But the glacial motion could 
bring forward moraine stuff and throw it down into the broad channels and 
pools of the glacial river which drained the ice field lying to the north. 

There are several enlargements of the delta-plain in China which are 
somewhat fan-shaped but not broad. They may indicate a gradual reces- 
sion of the ice before the sea and the formation of a series of small deltas 
in the open sea, or perhaps frontal deltas. 

The length of the system is about 15 miles. 


168 GLACIAL GRAVELS OF MAINE. 


CLINTON-ALNA SYSTEM. 


This notable gravel system appears to begin in the southeast part of 
Canaan. It takes its course to Clinton Village by a line which in general 
is quite straight, but has many minor meanderings. It is here a nearly 
continuous osar. At Clinton it turns southwest and follows the valley of 
the Sebasticook River for about 3 miles, and here it is somewhat discontin- 
uous, either because it was so deposited or on account of erosion by the 
river. About halfway between Clinton Village and Benton Falls the 
gravel leaves the valley of the Sebasticook and turns southward over a 
rolling country in Benton, Winslow, and Albion, being osar-like in form, 
but with several gaps at long intervals. From China southward the series. 
becomes conspicuously discontinuous, the short ridges being separated by 
intervals up to more than a half mile in length. The system follows the 
west shore of China Pond, passing a short distance west of South China, 
and at Chadwicks Corner, in the south part of China, expands into a plain 
near a mile long and more than half as broad. This plain ends in a rather 
steep bank on all sides. A well 73 feet deep, dug at a point on the slope of 
the plain, and probably 50 feet below the top, did not penetrate the sand 
and gravel. Overlying this plain is a scattered drift closely resembling 
till and containing many bowlders of shapes characteristic of the till. South 
of this point is a series of lenticular domes separated by the usual intervals; 
then a broad plain near a half mile wide extending from West Windsor to: 
a point 2 miles south of Windsor Village. This plain is rather level on 
the top, except that here and there are shallow basins and one deep lake 
basin. These plains are everywhere covered at the base by the marine 
clays, and are sprinkled on the tops and flanks by angular bowlders. The 
same sort of bowlders are scattered over the clays, though not so abun- 
dantly as on the higher gravel hills. They are probably of ice-floe origin. 
In Whitefield the gravel takes the form of a discontinuous series of short 
narrow ridges separated by numerous intervals of the usual length. It 
approaches the Sheepscot River near North Whitefield, follows this valley 
for several miles, and then in the southern part of Whitefield and northern 
part of Alna it expands into a delta-hke plain three-fourths of a mile in 
breadth and nearly twice that length. This plain is situated on the tops of 
the hills, 50 to 100 feet above the Sheepscot River. South of this plain 


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CLINTON-ALNA SYSTEM. 169 


there is an interval of a mile or more without gravel, and then a discontin- 
uous series of short and not very broad ridges, which extends from Alna Post- 
Office (Head of the Tide) southward to Sheepscot Bridge, lying most of the 
way along a valley situated west of the Sheepscot River. A short distance 
north of Sheepseot Bridge the glacial river turned abruptly east and flowed 
up and over a hill, and then descended into the valley of the Sheepscot 
River, where the gravel becomes a little broader. Thence a series of low 
mounds and short ridges is found near the river to a point about half a 
mile south of Sheepscot Bridge, where the system ends at the shore of 
Sheepseot Bay. Like many other systems, the mounds of gravel become 
smaller toward the south. I explored the country in Neweastle and Edge- 
comb lying south of where the system disappears. ‘There are many old 
beaches in the region, but no glacial gravels were found. 

At three places this large glacial river deposited deltas in the sea. 
These are situated near the line between Alna and Whitefield, in the cen- 
tral part of Windsor, and possibly another at Chadwicks Corner, in the 
south part of China. Perhaps near the top of the hills in the southern part 
of Clinton the system was above the sea, but in all the rest of its course it 
lies in a country covered by the marine clays. No system in the central 
part of the State contains so much gravel as this. 

Its length is 45 or more miles. ; 


ALBION BRANCH. 


A series of short ridges, separated by intervals of half a mile to more 
than a mile, begins about 14 miles northwest of Albion Village, and takes 
a course south and west to join the main system about a mile north of 
China Village. Toward the north the gravel is but little water washed; so 
the series probably does not extend far in that direction. 


WINSLOW-WINDSOR BRANCH. 


A discontinuous series of short ridges begins about a mile south of the 
Sebasticook River in Winslow and extends southward along the crest of 
the hills bordering the valley of Outlet Stream on the east. It thence 
extends southward past East Vassalboro and near the northeast angle of 
Webber Pond; thence southeastward to the head of Threemile Pond; 
thence across this pond and in nearly a straight line to a point about 2 
miles north of Windsor Village, where it joins the main system. 


170 _ GLACIAL GRAVELS OF MAINE. 


This series penetrates a rather level region and does not cross hills 
more than about 100 feet high. For its whole course it has been under the 
sea, and its bases are flanked and more or less covered by clay, often con- 
taining great numbers of marine fossils. The clay is more abundant along 
the line of the gravels than away from it on ground as favorably situated 
for the deposition of sediment by the sea. At the south end of Three- 
mile Pond, in Windsor, I had some difficulty in tracing the course of the 
osar river, as no gravel appeared on the surface. But passing obliquely 
up the hill at the south end of the pond was a belt about one-eighth of a 
mile wide which was free from bowlders, whereas there was a considerable 
number of bowlders on each side. Examination of the ravines of erosion 
on the hillside showed that here was a strip of clay much deeper than the. 
marine clay on each side, which was not thick enough to conceal the 
larger bowlders of the till. Going southward along the line of thick clays, 
the glacial gravels soon reappear, and plainly underlie the clay. I infer 
that the gravels were first deposited in a rather narrow channel in the ice. 
This channel was subsequently greatly enlarged, although still bordered 
by ice walls. In this broad channel kame border clay was deposited. In 
the southern part of Vassalboro, not far from Webber Pond, a fine blue 
clay, apparently the kame border clay, is highly fossiliferous. Finally the 
ice all melted and the whole region lay beneath the sea. A thin sheet of 
purely marine clay was now spread over the kame border clay and all the 
previously deposited drift. 

At several points along the line of this series short ridges are found 
at right angles to the main ridge. These were probably deposited by 
small tributary streams, yet in some cases they may be due simply to 
an abrupt enlargement of the main channel. Near the line of this series 
are a number of pinnacles and cones of till of quite irregular shape, which 
are more fully described elsewhere. Wells dug along the line of this 
series show that in general the sedimentary clay overlies the gravel. One 
well in Windsor, near the junction of this glacial stream with the main 
river, is dug through gravel into fine blue clay. Whether the gravel was 
deposited in this position by the glacial stream, or was washed down upon 
the clay by the waves of the sea, is uncertain. 

The length of the branch is 14 miles. 


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SYSTEMS OF GLACIAL GRAVELS. IU 


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— 


LOWER KENNEBEC VALLEY SYSTEM. 


The northern connections of this system are not explored, and they 
may extend into Harmony and Wellington, and perhaps farther. A gravel 
plain about one-half mile in diameter is found in the southwestern part 
of Harmony and southeastern part of Athens. Thence a discontinuous 
series of low bars and terraces extends several miles southwestward along 
a low pass. In places the appearance is as if an osar-plain had been 
eroded so as to leave fragments of its former self here and there, but in 
general the gravel seems to have been originally deposited discontin- 
uously. In the southeastern part of Cornville the gravel takes the form 
of a ridge, which extends nearly continuously through Canaan Village and 
thence southwestward through Clinton. It crosses the Kennebec River 
a short distance north of Somerset Mills and, as a continuous osar, follows 
the west side of the river through Fairfield Village and Waterville, below 
which place it becomes regularly discontinuous. Near Riverside, in Vas- 
salboro, the series again crosses the Kennebec, and is found on the east 
side of the river through most of Augusta. In Hallowell and Gardiner 
the ridges are again found on the west side of the river. At South 
Gardiner the system crosses to the east side again, and continues on that 
side through Pittston and Dresden, expanding into a broad plain-like 
ridge or terrace opposite Richmond Village. This plain is a delta of some 
sort, but under what conditions it was laid down I have not determined. 
South of this point the gravels are increasingly discontinuous. Glacial 
gravel appears at three places on the east side of Swan Island (Perkins 
Plantation); also at Abagadassett Point, in Bowdoinham, at the head of 
Merrymeeting Bay, the broad body of fresh water or lake into which the 
Kennebec and Androscoggin rivers flow. 

At South Gardiner and near Iceboro the gravels of this system form 
small islands in the Kennebec River. The largest plain in the whole system 
is the one near Moose Pond, in the southwest part of Harmony, at the north 
end of the system as here described. At this point a glacial stream flowed 
into either a glacial lake or the sea. It is not easy to determine the height 
of the sea in the vicinity of Moose Pond. Clays plainly marine extend 
up the Sebasticook Valley to Palmyra, where marine fossils are found. 


172 GLACIAL GRAVELS OF MAINE. 


Sedimentary clays of uncertain origin extend up the Sebasticook to near 
Hartland Village, not far from the southeast end of Moose Pond. From 
the southwest angle of the same pond a strip of sedimentary clay one-eighth 
to one-half of a mile wide is found along the line of the glacial gravel south 
and west through Cornville into Canaan, where they are plainly marine. A 
line of clays is also said to extend from Canaan eastward into Hartland. 
These facts prove that clay extends continuously up to the elevation of 
Moose Pond, 244 feet. The marine fossils in Palmyra have an elevation 
of 215-230 feet. It will be an interesting problem to determine how far 
the marine clay extends and where the kame border or the fluviatile clay 
begins, for the clays along the line of the gravel system in Cornville may 
have been deposited in a broad channel in the ice. The delta-plain near 
the west end of Moose Pond is two or three times as broad from west to 
east as from north to south. The coarsest matter is on the north; hence the 
streams flowed from that direction. 

In Cornville and Canaan both the gravel system and the bordering 
clays are strewn with numbers of large granite bowlders. Similar bowlders 
overlie the marine clays all the way to the sea, and they are probably floe 
bowlders. ae 

From Waterville to Bowdoinham the gravels of this system lie along 


the Kennebec River, or only a short distance from it. The road gravel of 


Augusta, Hallowell, and Gardiner comes from this series. In a few places 
the mounds and short ridges form hills 50 to 70 feet high, and some of 
them form a conspicuous feature of the scenery of this beautiful valley. 


Among these is the hill situated on the west side of the river just south of 


South Gardiner, where the Maine Central Railroad has cut through about 
30 feet of gravel and cobbles. 


This system shows a decided tendency below Waterville to follow the | 


crests or slopes of the hills on one side or other of the river rather than to 
follow the bed of the river. In general the material is from the size of cob- 
bles down to sand grains, but here and there the higher hillocks contain 
bowlderets, and sometimes bowlders 2 to 3 feet in diameter. A pinnacle 
near the north line of Augusta consists, judging from what can be seen on 
the surface, of a mass of stones and bowlders but little water polished and 
much resembling till. 
Length of system, 55 miles. 


LOWER KENNEBEC VALLEY SYSTEM. 173 


Short eskers are reported by E. P. Clarke as occurring not far from 
Sidney Post-Office. They lie more than a mile west of the Kennebec 
Valley system, and are either local, or, perhaps, branches of this system. 


SHORT ESKERS SOUTH AND SOUTHWESI OF MOOSEHEAD LAKE. 


Several short ‘‘horsebacks” have been reported to me as being found 
in the western part of Shirley, in East Moxie and Bald Mountain town- 
ships, and in the western part of Blanchard, near Bald Mountain Pond. 

Near the west end of Kingsbury Pond, in Mayfield and Brighton, a 
series of several gravel ridges comes from the north down a hill into the 
level ground near the pond. They become reticulated, and then toward 
the south the ridges become lower and broader and finally coalesce into a 
rather level delta-plain. The ridges are hardly a mile long, and they appear 
to be simply a side-hill system. 

Another hillside esker is found on the southern slope of a hill which 
lies on the north side of Kingsbury Pond, near the line between Mayfield 
and Kingsbury. The ridge ends near the base of the hill, but does not 
expand into a delta-plain, unless it be beneath the pond. 

Low passes extend from Kingsbury Pond both north and south, so 
that all the above-named gravels might possibly form a series connecting 
either with the Hartland system through Harmony Village, or with the 
Lower Kennebec system through the west part of Harmony and Athens, 
or down the Wesserrunsett Valley into Brighton and Athens, or southwest 
along the valley of Fall Brook toward Solon. I have not explored the 
country thoroughly. From present information I regard all the short 
kames above mentioned as local, isolated eskers, not branches of a common 
system. They were a feature of the last part of the Glacial period, when 
the ice was retreating northward. 


LOCAL ESKERS IN RICHMOND AND BOWDOINHAM. 


A short ridge of glacial gravel and cobbles is found in the western 
part of Richmond Village. About 2 miles west of the village, near Abaga- 
dassett Stream, are a few short, rather flat-topped ridges with no traceable 
connections. ‘They appear to be small marine deltas. A few miles south- 
east of this place is an east-and-west ridge of till on the east side of Swan 
Island, in the Kennebec River. This is probably a small terminal moraine. 


174 GLACIAL GRAVELS OF MAINE. 


If so, these local kames in Richmond date from about the same period and 
were probably deposited by short glacial streams in the sea at or near the 
front of the retreating ice. Another short local kame is found near the line 
of the Maine Central Railroad about 14 miles south of East Bowdomham. 


SEDIMENTARY DRIFT OF THE UPPER KENNEBEC VALLEY. 


The student of the drift of Maine who begins at the mouth of the 
Kennebec River and travels northward will at once observe that the lower 
portions of the valley are bordered by no such system of terraces as those 
of the classic upper Connecticut Valley. There is a low terrace of valley 
drift near the present limit of high water. Above that the only terraces are 
those eroded in the marine clay or till. The marine clay near the river 
differs but little in composition from that found several miles away from it, 
and is thus proved to be a rather deep-water deposit. The clays cover the 
valley to a breadth of many miles. 

From Waterville northward there is a change in the character of the 
sediments of the valley. Resting on the till or unmodified glacial drift is 
a thick sheet of sedimentary clay, overlain by a stratum of coarser sedi- 
ments. The latter composed the delta sands of the river when the sea stood 
at 230 feet. Marine fossils have been found in the lower clays as far north 
as Norridgewock. At North Anson fresh-water clam shells have been 
found in brick clay several feet below the surface. This clay is apparently 
of the same age as the rest of the underclay of the valley. But the unio 
shells were found near the base of a terrace of erosion, so that it is not certain 
whether they were deposited in the original underclay of the valley or in 
a more recent erosion channel. From Norridgewock to the coast the low- 
est layers of the clay are dark in color, often almost black, and often with 
the odor characteristic of the clam flat. Farther up the valley the under- 
clay becomes bluish gray in color and is slightly coarser, sometimes even 
silty. The underclay extends continuously up the Kennebec Valley to a 
point 2 miles north of Bingham; also up the larger tributaries for a consid- 
erable distance above their junctions with the Kennebec. The underclay 
partly covers the Anson-Madison glacial gravels, and near Solon overlies 
local beds of well-rounded cobbles. It is thus evident that glacial gravels 
were first deposited at various points in the valley, and that these were sub- 
sequently covered by the clay. From being near three-fourths of a mile 


SEDIMENTARY DRIFT OF UPPER KENNEBEC VALLEY. 16) 


wide at Bingham, the clay broadens to 2 miles or more in Solon, Embden, 
Anson, and Madison, while below that poimt the marine beds are several 
miles in breadth. It is not probable that the clay covers the central parts 
of the valley north of Solon Village. 

From Waterville northward to Norridgewock we find overlying the 
sedimentary clay a stratum of sand rather horizontally stratified, except 
where it has blown under the action of the wind. In Fairfield and Skow- 
hegan this sand forms plains extending back from 1 to 3 miles from the 
river, and it is plainly a marine formation, i. e., the fluviatile Kennebec 
delta. In places it has been removed by the wind or by stream, and it is 
difficult to. trace its original distribution. Northward the sand becomes 
coarser by degrees and in Madison passes into mixed sand and gravel, 
while by the time Solon is reached cobbles and bowlderets are found more 
than a foot in diameter along the central parts of the valley. From this 
point to within three miles of the Forks well-rounded pebbles, cobbles, 
bowlderets, and in places bowlders are found along the central part of the 
valley, while at the sides of the valley the stones are not so large and are 
less waterworn. At the sides of the valley this coarse stratum plainly 
overlies the underclay. ‘The sections observed by me did not show clay 
beneath the gravel at the axis of the valley; yet this may be due to the 
sliding down of the overlying gravel. Only at a few places did I find clay 
_ in the banks of the river above Solon, and then it was uncertain whether it 
was sediment of recent deposition or an uneroded portion of a stratum which 
once covered the valley. It thus appears that there is little or no clay 
beneath the coarse drift found along the axis of the valley. 

The so-called “‘horsebacks” are among the most interesting features of 
the upper Kennebec Valley. From Solon to Bingham a nearly continuous 
two-sided ridge is found along the west side of the river, and from that 
point northward to within 3 miles of The Forks a similar ridge is found for 
most of the way on the east side. hese ridges rise 20 to 80 feet above 
the alluvium at their sides. What is the cause of these ridges? 

Where they are broad enough to have a flat top, they have, by aneroid, 
substantially the same height as the broadest of the alluvial terraces at the 
sides of the valley, that which constitutes the main sedimentary plain. 
Where they are narrow, they are usually lower than this terrace, and often 
almost merge into an uneven or hummocky terrace many feet lower than 


176 GLACIAL GRAVELS OF MAINE. 


the principal terrace. The slopes of these ‘‘ horsebacks” are about as steep 
on the side away from the river as the erosion cliff which forms the bank 
of the river. The depression between the central ridges or horsebacks and 
the alluvial terraces at the sides is of varying breadth up to one-eighth 
of a mile or a little more. This depression, being of varying depth and 
confined between the central. ridge and the lateral terraces, presents a suc- 
cession of basins or kettleholes. Some of these are so deep as to contain 
lakelets without visible outlets. Some of these ponds are said to rise and _ 
fall with the water of the river. One pond in Moscow is said to be 40 feet 
deep in time of high water. By aneroid its surface was several feet higher 
than the river; hence it must be fed by springs from the side of the valley 
faster than the water seeps through the alluvium into the river. All this 
favors the hypothesis that there is a body of coarse alluvium along the 
central part of the valley rather easily permeable by water. In some 
other respects the interpretation of the facts is beset with difficulties. The 
ridges plainly have the appearance of being uneroded portions of an 


CE i As oe 
Te ieee 


Fic. 20.—Section across Kennebec Valley. a, present situation of river. © 


alluvial plain which once extended across the valley. It is not so easy to 
account for the basins and lakelets in a valley of erosion. Here is the - 
bottom of a so-called channel of erosion 50 to 75 feet higher at one place 
than at another only a short distance up or down stream. Such ups and 
downs are of frequent occurrence in the depression situated between the 
ridges and the terraces at the sides of the valley away from the river. If 
this depression has been cut down into the alluvial plain by water, then we 
must account for the very unequal depth of the channel. This question 
will be referred to hereafter. If we assume that the two-sided ridges result 
from the unequal erosion of a once continuous alluvial plain, why did not 
the river continue enlarging its channel laterally instead of forming a new 
one on the other side of the valley, leaving the central portion of the plain 
uneroded? The true answer to this question probably is that the alluvium 
of the central part of the valley is composed of so much larger stones that 
it is less easily eroded than the drift at the sides. In many places the 
central ridge is largely composed of cobbles and bowlderets, and for some 


SEDIMENTARY DRIFT OF UPPER KENNEBEC VALLEY. Ae 


distance in the southern part of Forks Plantation it also contains many 
bowlders 2 to 4 feet in diameter. 

Is there an ordinary osar along the axis of the valley, which was sub- 
sequently covered and flanked by river drift? I regret that the numerous 
sections examined by me along the windings of the river were not free 
from surface sliding. I could not find an ordinary osar of arched strati- 
fication along the valley, but the sediments appeared to become finer 
by degrees as we go back toward the sides of the valley, and the coarse 
central belt showed no distinct border. This kind of assortment is charac- 
teristic of the osar-plain, and probably also of fluviatile drift. The stratifi- 
cation of the central ridge could not be distinctly made out, but appeared to 
be rather horizontal. The pebbles and cobbles are well rounded, far more 
so than in ordinary valley drift off from lines of glacial gravel. The 
average slope of the Kennebee River from Moosehead Lake to tide water 
at Augusta is about 9 feet per mile, and from The Forks to Norridgewock 
it is probably not more than 4 to 6 feet per mile. Below Bingham the 
central ridges contain bowlderets more than a foot in diameter at a point 
where the alluvial plain is near three-fourths of a mile wide. Above 
Bingham the valley narrows to about one-fourth of a mile, here and there 
expanding to a half mile or more. If the whole alluvial plain is ordinary 
river drift, a very broad and swift river is necessary to transport such large 
stones and to roll and round them so thoroughly. The question as to 
whether so moderate a slope could have given the necessary velocity of 
current will be considered later. My exploration of this part of the Kenne- 
bee Valley was made in 1879, before I recognized the osar-plain. I 
therefore somewhat doubtfully outline the history of the upper Kennebec 
Valley as follows: 

First, glacial gravels were deposited in the valley between The Forks 
and Solon by glacial streams flowing in narrow channels between ice walls. 
These gravels are now deeply buried and have been found only here and 
there. Subsequently an osar-plain was formed along the axis of the valley 
ina much broader ice channel. This channel gradually broadened, until 
at last it extended across the whole valley, at which time the river ceased 
to be a glacial stream. The gradual retreat of the ice from the center of 
the valley is probably the explanation of the fact that the alluvial plain of 


the Kennebee does not extend back into several of the lateral valleys which 
MON XXXIV. 12 5 


173 GLACIAL GRAVELS OF MAINE. 


join the main valley in this part of its course. A well-marked instance is 
found on the west side of the Kennebec about 3 miles north of Solon Vil- 
lage, where a valley covered by ordinary till comes from the northwest into 
the main valley. The Kennebec alluvial plain rises 8 feet or more above 
the lateral valley, and once formed a dam across it, but shows no tendency 
to extend back into the valley. This valley would have formed a lateral 
bay of the main river at the time the alluvial plain was being deposited if 
it was not covered by ice. Near the mouth of the Pleasant River—a small 
stream forming the outlet of Pleasant Pond, in Carratunk—there is an abrupt 
enlargement of the valley of the Kennebec toward the east, and the coarser 
sand and gravel plain found near the river does not expand to fill the broad 
valley, but is bordered by an area of silt and clay on the east side. This 
_ clay extends for some distance up the lateral valley. I see no reason why 
all the lateral valleys would not be covered by such a clay at least to the 
height of the higher Kennebec terrace, if the water were free to flow back 
into them at the time the terraces were being deposited. he fact that some 
of the lateral valleys are not covered by such sediments, though they are 
not so high as the higher terraces, favors the hypothesis that the ice still 
lingered in them after it had disappeared in the main valley. 

Directly after the melting of the ice in the valley the currents flowed 
gently, and the underclay was now laid down in the bottom of the valley, 
flanking the previously deposited osar-plain. Finally there came a time of 
swifter floods, when the clays were covered by coarse sediments over the 
whole of the valley (up to 8 miles broad). Much of this sand and gravel 
and cobbles was probably derived from the central osar-plain, which was 
now in part eroded and spread laterally over the whole valley. At this 
time the river was pouring its mighty volume of waters into the sea in 
Anson and Madison or northward, while estuarine conditions prevailed for 
some miles above that point. Subsequently the sea retreated to its present 
position, but at this time the Kennebee had become much reduced in vol- 
ume, and the change in level must also have been quite rapid, or a delta- 
plain of sand would have been left over all the lower part of the valley. 
As it is, the delta sands of the Kennebee poured into the sea can not be 
traced south of Waterville. Below that place the whole of the broad area 
occupied by the sea is covered by clays, and these were rather deep-water 
deposits, formed some considerable distance from where the Kennebec River 


ANSON-MADISON SERIES. 179 


poured ito the sea at the time it was depositing the broad delta sands of 
Solon, Embden, Anson, Madison, Skowhegan, and Waterville. 

A comparison of this valley with others at the same distance from the 
coast strongly points to the conclusion that the broad gravel, sand, and clay 
plains extending from Embden and Solon northward are frontal or overwash 
plains, dating from the time when the ice had retreated to a point north of 
Bingham. ‘These vast deposits, consisting of the underclay and the sur- 
face sands and gravels, were laid down upon a series of still older gravels 
which were of purely glacial origin and have been seen only in a few 
places. The glacial river probably flowed down the Kennebec Valley to 
Norridgewock and then southward, not along the river to Skowhegan. A 
low valley covered by clays and silts, probably marine, extends from Nor- 
ridgewock southeastward into Fairfield, and two other valleys, covered by 
fine sediments, extend southwestward into Belgrade. The last named are 
along lines of glacial gravels. 

The glacial, fluviatile, estuarine, and marine sediments are all repre- 
sented near Norridgewock, and the region is a difficult one to understand. 

A sedimentary plain several miles broad covers the lower portion of 
the valley of the Sandy River. Its general character resembles that of 
the Kennebec Valley at the same elevation. This alluvial plain connects 
southward by two lmes of clay with the marine clays. One of these 
lines of clay extends from Mercer Village southeastward through Belgrade 
to Augusta; the other from Farmington Falls southward through Chester- 
ville, Fayette, and East Livermore to Leeds and Sebatis. The origin 
of these sediments situated above the 230-foot contour will be discussed 
later. 

ANSON-MADISON SERIES. 

A dome of kame gravel 75 feet high is found on the south bank of 
the Carrabassett Stream about 4 miles northwest of the village of North 
Anson. Three other similar deposits, separated by gaps up to a mile in 
length, are arranged in a line from this point southeastward. Then appears 
a rather continuous ridge which crosses a very low divide and subse- 
quently follows the valley of Getchell Brook for several miles southeast- 
ward through Anson. The gravels pass one-half mile west of Anson 
Village (Madison Bridge), cross the Kennebec a short distance north of 
the mouth of Sandy River, and then appear as a ridge on the east side 


180 GLACIAL GRAVELS OF MAINE. 


of the river for about three-fourths of a mile. The southern portion of 
this ridge is so disguised by the sands and clays of the valley that it 
is uncertain whether it ends in a delta-plain or not. 

The stones of the series are polished, but in general not so much so 
as those of the long systems. A noticeable feature of this series is that 
it is discontinuous at its northern extremity in the same way that the long 
osars usually become discontinuous at their southern ends. 

The relation of this system to the osar border clay and the alluvium 
of the Carrabassett Valley is interesting. The gravels at the southern 
extremity of the series are more or less covered by the clay and sand 
of the Kennebec Valley. Northward in the valley of the Carrabassett 
the gravels are flanked by a plain of nearly horizontally stratified fine 
sediments. This bordering plain is of varying breadth up to one-fourth 
of a mile, and extends all the way to the Carrabassett Stream. Clay 
and silty clay are most abundant in the border plain, but some layers 
of sand alternate with the clay. The fact that this plain follows the course 
of the glacial’stream up and over a divide, rising above the alluvial plain of 
the Carrabassett Valley 20 or more feet by aneroid, proves that the clay 
along the line of the kames was not due to an overflow of the Carra- 
bassett River, but was deposited in a broad ice channel. Here and there 
on the border plain of clay are bowlders 2 to 4 feet in diameter. They 
have the shapes of the ordinary till bowlders, and were probably depos- 
ited by floating ice. Near the line of the gravels 15 miles south of 
the Carrabassett, wells 30 feet deep do not reach the bottom of the 
clay. At this point is an interesting feature of the osar border plain. 
Toward the east it is continuous with and fully as high as the broad 
plain of sand and clay which extends about 5 miles northeastward across 
the Carrabassett River into Embden. But toward the west the clay 
border plain slopes down rather steeply to a swamp, one-half mile or more 
wide, which is about 20 feet lower than the plain itself. A small brook 
flows from the swamp northeastward across the sedimentary plain to the 
Carrabassett, having eroded a deep and narrow ravine init. This small 
stream can not have eroded the clay over several hundred acres at the 
swamp and only a narrow strip over the rest of the alluvial plain. On 
the north side of the Carrabassett opposite this point there is a valley 
extending back farther from the river than this, yet it is covered with 


NORRIDGEWOCK-BELGRADE SYSTEM. 18] 


sand and clay to the base of the high hills. It does not seem possible 
the kame border plain could end so abruptly as it does on the west at 
the swamp above mentioned, unless at the time of deposition, of the border 
clay as well as of the alluvium of the Carrabassett Valley at this point, 
the area where the swamp now is was then covered by ice. It is possible 
that the border clay itself happened to be just high enough to prevent the 
water of the Carrabassett from passing westward, though that condition 
would be extraordinary. 

Apparently the glacial history of the region along this gravel series 
is as follows: A small glacial stream deposited the gravels in rather narrow 
channels within the ice. By degrees this channel became widened to 
several times its original breadth, and in this broad channel was deposited 
the osar border clay. Then the ice on the east side of the border clay 
melted and the border plain was submerged in the great sheet of (estu- 
arine?) water which then filled the valley of the Carrabassett to a breadth 
of several miles. But the ice on the west side of the osar channel, where 
the swamp now is, probably still lingered for a time and prevented the 
deposition of fine sediments over that part of the valley. The swamp 
would naturally be covered by a pond previous to the cutting of the 
ravine of erosion to the Carrabassett by tle small brook, its outlet. 

Some of the short deposits of gravel at the north end of the series may 
be small delta-plains, and mark stages in the extension of the broad glacial 
channel northward. A possible connection of the Anson-Madison series is 
found in Embden. A kame about three-fourths of a mile wide is found 
between Fahi and Sands ponds, in Embden, and another near Hancock 
Pond. I did not explore the region about Embden Great Pond, and do not 
know whether there is a continuous series of gravels between the two noted. 
It is quite possible this is a branch of a Kennebec Valley glacial river. 

Length of the Anson-Madison series, about 10 miles. 


NORRIDGEWOCK-BELGRADE SYSTEM. 


Provisionally these gravels are classified as a distinct system, though a 
sufficiently careful search beneath the sedimentary sand and clay of the 
Kennebec Valley may yet show that they are a continuation of the Anson- 
Madison system, and that both are connected with the gravels of the upper 
Kennebec Valley. 


182 GLACIAL GRAVELS OF MAINE. 


The series begins near the south line of Norridgewock as a number of 
ridges separated by intervals varying up to near 1 mile. The series extends 
southwestward along a low pass to Smithfield Village, where it expands into 
a plain more than 50 feet high. On the north the plain is continuous for 
about one-fourth of a mile from east to west, and it sends out three parallel] 
tongues south for one-third of a mile. The material is coarse gravel and 
cobbles at the north side of the plain, but becomes rapidly finer toward the 
south, passing into fine sand, and this into sedimentary clay. A continuous 
plain of sedimentary clay extends from Norridgewock along the line of this 
gravel series, and thence all the way to Augusta. The surface of this clay 
is strewn with numbers of stones and angular bowlders 2 to 12 feet in 
diameter, but not with anything resembling a sheet of till; hence I refer 
the erratic bowlders to floating ice. The bowlders may have been deposited 
either in a broadened osar channel, in which case this is a plain of osar 
border clay, or in an arm of the sea, or in an overflow channel of the great 
Sandy River (Kennebec estuary of that time). The gravel plain at Smith- 
field Village is a delta-plain of some sort, and it is situated at about 350 
feet elevation by aneroid. This makes it probable that the glacial stream 
here flowed into a glacial lake, or, what is equivalent, a broadened osar 
channel. For several miles south of this point the clays bordering this 
gravel series have an elevation of more than 250 feet. 

South of Smithfield Village there is apparently no gravel for about 2 
miles, and then a series of gravel ridges crosses the northeastern arm of 
Belerade Great Pond. It appears for about a mile on the east shore of the 
pond, and at Horse Point runs southward into the water as a long gentle 
sloping cape. It reappears on the south side of the pond, and soon takes 
the form of a series of reticulated ridges inclosing kettleholes and lake- 
lets. About a mile north of Belgrade station of the Maine Central Rail- 
road a rather level plain extends for one-fourth of a mile or more to the east 
of the main ridge. It was thrown out from the west around the south end 
of the high hill known as Belgrade Ridge. It consists of rather horizontally 
stratified fine gravel and sand, with a few layers of clay, and is plainly a 
small delta. To theeastof this deposit lies the valley of Messalonskee (Snows) 
Pond, in Belgrade and Sidiiey. The plain in question is from 40 to 60 feet 
above the pond, which is 240 feet above the sea. Hast and northeast of the 
delta-plain just described no sedimentary clay appears on the northwest side 


NORRIDGEWOCK-BELGRADE SYSTEM. 183 


of Messalonskee Pond for several miles toward Oakland. If the sea stood 
at the level of this delta-plain, it would at that time have filled the valley 
of Messalonskee Pond, and a deep sheet of salt water 4 miles or more wide 
would have extended northward from the northwestern part of Augusta 
through Belgrade, Sidney, Oakland, and Waterville, and such a body of 
water must have deposited abundant sediments. The sudden disappearance 
of the clay a short distance east of the osar-ridges north of Belgrade station 
is inconsistent with the hypothesis that the delta above mentioned was 
deposited in the open sea. On the contrary, these facts strongly favor the 
theory that the delta-plains which appear at intervals in the course of the 
system from the south part of Norridgewock to Belgrade station were 
deposited in glacial lakes, and that the bordering plain of sedimentary 
clay is osar border clay, laid down in a very broad channel within the ice, 
or perhaps partly bordered by the hills. 

South of this point the gravel takes the form of a continuous ridge for 
several miles, being cut through by the Maine Central Railroad at Belgrade 
station. Just south of the station the ridge is strewn with many good-sized 
bowlders having till shapes. In the southeastern part of Belgrade the 
system expands into a broad series of reticulated ridges inclosing numerous 
kettleholes and basins containing twenty lakelets, most of them without 
visible outlets. On the west of these plains the ridges have steep side 
slopes, and are simply windrows of coarse gravel, cobbles, bowlderets, and 
bowlders, all very well rounded. Going south and east we find the ridges 
becoming lower and broader and the matter contained in them finer, and 
they presently blend into a rather level plain of fine gravel and sand in 
the northwestern part of Augusta, and this soon passes by degrees into 
marine clay at an elevation of near 250 feet or more. 

A short ridge in Manchester is the only glacial gravel found south of 
this system, and that is probably not connected with this. This series dates 
from the last part of the Glacial period, when the ice had retreated so far 
northward that the glacial river flowed into the sea in the northwest part of 
Augusta. South of where this glacial river flowed into the sea the clay is 
very deep. A stream has eroded it to a depth of 80 feet, and yet apparently 
has not cut to the bottom. There is an old sea beach on the hill lying just 
west of Augusta, being especially well developed on the southern brow of 
the hill near the top. Otherwise I have not been able to find any very 


184 GLACIAL GRAVELS OF MAINE. 


well-developed beach in this region. It is therefore evident that the deep 
sheet of clay northwest of Augusta represents eroded till in only a small 
proportion, but was chiefly composed of the mud brought mto the sea by 
the glacial river at the delta of Augusta and Belgrade above described. 


NORTH POND BRANCH. 


A north-and-south ridge of glacial gravel crosses North Pond in the 
northeast part of Rome. It nearly divides the pond ito two parts. Jts 
connections are unexplored. Probably it is a branch of the Belgrade sys- 
tem, yet it may vrove to be a local deposit. 


MERCER-RELGRADE BRANCH. 


An irregular mound of glacial gravel 80 feet high and one-eighth of a 
mile in diameter is found not far south of Mercer Village, at the northeast 
base of Hampshire Hill. A nearly north-and-south valley in Mercer, 
Rome, and Belgrade extends for several miles along the eastern base of 
this high hill, and in this valley two streams take their rise, one flowing 
north to Mercer Village, the other south and west into Belgrade Great 
Pond. A well-defined gravel series extends along this valley, now taking 
the form of terraces near the base of the hill and now appearing as a two- 
sided ridge in the midst of the valley. The ridges are 10 to 20 feet in 
height—nowhere so high as the large hummock at the north end of the 
series. The series does not expand into a delta-plain near Belgrade Great 
Pond, into which it runs from the north, making it probable this was a 
tributary of the Belgrade system. At the southwest angle of this pond 
a short gravel ridge, which is in a line with the Mercer-Belgrade series, is 
found, about half a mile west of the main system, which may be a part 
of the Mercer series. 

The valley along this gravel series is deeply covered by sedimentary 
sand and clay, which on the north is continuous with the broad alluvial 
plain of the Sandy River Valley, and on the south there is a line of similar 
clays along the outlet of Belgrade Great Pond all the way in its circuitous 
route to Messalonskee Pond, near Belgrade station. ‘There seems to have 
been an overflow of the great Sandy River estuary this way, and previous 
to the melting of the ice there may have been some border clay deposited 
along the flanks of the gravel ridges. This makes the problem of the clays 
of this valley rather complex. 


UPPER KENNEBEC VALLEY. 185 


The glacial gravels in Mercer, Norridgewock, Smithfield, Rome, and 
Belgrade are found in a region diversified by numerous quite high hills, 
many of them granite knobs. Between these hills are several valleys, 
forming very low passes from the valley of the Sandy River south and 
southeast. The courses of the glacial rivers were over a gently rolling 
surface. : 

The length of the series from Mercer to Belgrade is about 10 miles. 


LATE GLACIAL HISTORY OF THE UPPER KENNEBEC VALLEY. 


When we compare all the facts regarding the Kennebec Valley with 
those elsewhere recorded regarding the neighboring valleys situated at 
about the same distance from the sea, viz, the East Branch of the Penob- 
scot, the Pleasant River, the upper Piscataquis, Dexter, and Main streams, 
the upper Sebasticook, Carrabassett, and Sandy River valleys, we seem to 
have ground for the following interpretation of the facts: 

The earlier glacial streams of the upper Kennebec Valley left no sedi- 
ments (that I have discovered), or they have been buried out of sight. The 
osar river that flowed from Norridgewock southward dates from a late 
period, when the ice had already melted so far north that this river flowed 
into the sea in the northwestern part of Augusta. The northern tributaries 
of this river must have drained the upper Kennebec Valley, but it is as yet 
uncertain whether they deposited any gravels during the time in which the 
river continued to flow south of Norridgewock. The flow of this glacial 
river south of that place was presently stopped by the retreat of the ice 
and the advance of the sea up the Kennebec Valley to near Madison 
Bridge, north of Norridgewock. The Anson-Madison osar probably dates 
from about the time the sea advanced to Norridgewock. About this time 
the upper Kennebec osar river began to deposit gravels im that part of its 
channel lying north of Solon. Later the ice over the bottom of the valley 
had all melted as far north as Embden or Solon. By this time the osar 
channel extending nearly from The Forks to Solon had broadened to an 
osar-plain channel, with reticulations and outliers in various parts of the 
valley, and the mighty glacial river that poured south from Bingham and 
Solon formed a frontal plain of gravel and sand which extended a few miles 
southward and then was continued to the sea as a frontal plain of clay (the 
underclay of the valley drift of this part of the valley). The character of 


186 GLACIAL GRAVELS OF MAINE. 


the sedimentary drift of the interior of the State thus evidences the pro- 
gressive retreat of the ice, also the probability that the longer glacial rivers 
did not deposit sediment in all parts of their long channels simultaneously. 


SHORT ESKERS IN MANCHESTER AND LITCHFIELD. 


The following gravel deposits do not seem to have connections, and 
are probably so many local kames. 

A small ridge is found a short distance east of The Forks, Man- 
chester. A similar ridge is found in the east part of Bowdoin, and still 
another a short distance east of Litchfield Post-Office; and there are several 
ridges forming almost a series in the valley of the Cobbosseecontee Stream 
in Litchfield. All these are well disguised by the marine clays. Litchfield 
Plains are a small marine delta, without traceable connections. This plain 
will be more fully described later. 


LITCHFIELD-BOWDOIN SYSTEM. 


Purgatory Stream rises in the southwestern part of Litchfield and 
flows northeast into the Cobbosseecontee Stream. About a mile north of 
the south line of Litchfield an osar-plain begins in the valley of Purgatory 
Stream and goes southward up this valley to its end. The gravel system 
then crosses a hill about 100 feet above its north end, being somewhat 
interrupted near the top of the divide, and then continues southward through 
Webster into Bowdoin. Not far north of West Bowdoin the series expands 
into a plain 2 miles or more long, the gravel becoming finer toward the 
south and quite level on the top, passing from sand into marine clay. It is 
somewhat fan-shaped, and was a delta deposited in the open sea. At the first 
settlement of the country it was overgrown by huge pines and was called 
the “Pine Nursery.” Many masts of ships were procured here. South of 
this point the system becomes very discontinuous, and consists of several 
lenticular ridges or domes, separated by rather short gaps. A mound of 
this series situated just east of West Bowdoin incloses a deep kettlehole. 
Its flanks are partly covered by blowing marine sand, and it is sprinkled 
with some large bowlders having the shape of till bowlders. 

This is a short series, but contains a large amount of gravel and sand 
for its length. The stones are fairly well rounded. The breadth of the 
gravel plain at the north end of the system is one-eighth mile or more, a 


U. S. GEOLOGICAL SURVEY 


MONOGRAPH XXXIV PL. XIV 


A TUNNEL IN DOME-LIKE GRAVEL MASSIVE: WEST BOWDOIN 


Hollow due to accident of original deposition, not to erosion 


B RAVINES IN GRAVEL PARALLEL IN DIRECTION TO THE GLACIAL RIVER; DURHAM. 


DEAD RIVER-JERUSALEM SYSTEM. 187 


ereater breadth than usual in such a situation. The valley of Purgatory 
Stream to the northeast is from one-third of a mile to more than a mile in 
breadth. The appearances are as if the valley was occupied by a local 
tongue of ice which continued its motion while the gravel plain was being 
deposited. If so, the space between the front of the ice and the hill to the 
south would be occupied by a broad glacial stream, or by a lake, and the 
osar-plain may in part partake of the nature of a water-washed terminal 
moraine. 

The system evidently dates from a late period of the Ice age, since 
the marine delta near its southern extremity is situated so far from the 
present coast. 


LOCAL ESKERS IN NORTHWESTERN MAINE. 


Horseback at Leadbetter Falls— These falls are situated on the Penobscot River 
near its source. Prof. C. H. Hitchcock describes a ridge, presumably of 
glacial gravel, as follows: ‘At the farther end of the portage is a large 
horseback, which terminates here in a ledge larger than the ridge itself. 
We traced this horseback up the river for 3 miles, and found it was not 
parallel with the river itself.”* 

Parlin Pond horsebacks —Professor Hitchcock also describes a horseback near 
Parlin Pond, as follows: “Northwest from Parlin Pond there is a curving 
horseback three-fourths of a mile long.”’ I am informed that there is 
another similar ridge northeast of the pond, near its outlet. 

Kibby Stream horseback—A two-sided ridge, probably of glacial gravel, is 
reported by Mr. A. J. Lane, of Lexington, and others as being found 
between Spectacle Pond and Kibby Stream, which flows into Dead River 
at Grand Falls. 


DEAD RIVER-JERUSALEM SYSTEM. 


rom the great bend of the Dead River in Dead River Plantation, a 

1 the great bend of the Dead R Dead R Plantation, 
very low valley extends southward past the east base of Mount Bigelow. 
og Brook takes its rise near the highest part of this pass and flows slug- 
Bog Brook takes it the highest part of this ; 1 fl lug 
gishly northward to the Dead River. A ridge of sand and gravel begins a 
short distance south of Dead River and follows the valley of Bog Brook. 
orms a natural roadway through a low level region near the axis of the 

It f tural roadway through a low level reg tl 1 


‘Second Annual Report upon the Natural History and Geology of the State of Maine, p. 345, 1862. 
2Tbid., p. 399. 


188 GLACIAL GRAVELS OF MAINE. 


valley. According to the information which has reached me, there are two 
low passes from the head of Bog Brook, one southward along a branch of 
Sevenmile Stream to Kinefield, the other southeastward through Lexington 
to New Portland. A large plain of sand and gravel is found in the valley of 
Sevenmile Stream above Kinegfield; also in the Carrabassett Valley above 
North New Portland. These sediments extend across the valleys in the 
position proper to valley drift. The gravel may have been brought down 
from the Dead River region by glacial streams at a time when the ice still 
remained in the valley of Dead River, but had melted over the valleys to 
the south. It is quite possible also that some of the alluvium of these val- 
leys is after the order of the osar-plain. My exploration of these valleys 
did not reach above Kingfield and North New Portland. 

Stratton Brook horseback— A two-sided ridge is reported by Rev. Stephen 
Allen, of Winthrop, as being situated between Stratton Brook and the road 
from Eustis to Kingfield. It is said to begin 4 miles from Eustis and to 
extend 3 miles southeastward. 

A horseback 3 miles long is reported as being found near the divide 
between Arnold River, a tributary of the Chaudiere, and the Dead River, 
above Chain Lakes. 


NOTE ON THE NORTHWESTERN PART OF MAINE. 


West of the Kennebec River and north of a line drawn from the 
upper Androscoggin Lakes to Anson, the glacial gravels appear to be 
scanty as compared with those of the area south of that line. But the 
same can be said of the whole of the State northeastward at the same 
distance back from the coast. The distinct ridges are short, and several of 
them are lost in a sedimentary plain that presents the external features of 
a frontal plain of glacial sediments. The relations of the osars to the 
frontal plains of apparent valley drift, and of these to the silty and clayey 
plains which reach all the way down to the old sea-level, furnish an intri- 
cate problem. The matter will be discussed more fully hereafter. A com- 
parison of the alluvium of the valleys of the streams situated in the 
interior of the State, from the Sandy River to the East Branch of the 
Penobscot, reveals many features common to all of these valleys. Perhaps 
no one of them would alone warrant the belief that these plains of sand, 
gravel, silt, and clay which reach from the extremities of the short osars 


READFIBLD-BRUNSWICK SYSTEM. 189 


are frontal plains of glacial sediments, but all together make out a strong 
case. Every time I review the subject I am more impressed with the weight 
of this cumulative evidence. 

All the facts so far as known indicate that the short eskers and osars 
of northwestern Maine are a feature of the very last part of the glacial 
epoch, when the ice had retreated as far north as this region, and the 
glacial rivers were consequently rather short. 


READFIELD-BRUNSWICK SYSTEM. 


This interesting system begins 2 miles northeast of Readfield Village 
as a low ridge of rather fine subangular gravel, which extends about 1 mile 
south to Lake Maranocook. No glacial gravel is known to appear on the 
shore of this lake until we reach Winthrop Village The eastern part of the 
barrier which separates the upper and lower Winthrop lakes is underlain by 
rock at a depth of a few feet. Along the line of the Maine Central Rail- 
road, in the western part of the village, is a north-and-south valley extend- 
ing from one lake to the other. The surface of this valley rises about 20 
or 25 feet above the upper pond, and wells show it to be covered by glacial 
sand and gravel, flanked by sedimentary clay, to a depth of more than 40 
feet. Evidently the preglacial drainage flowed along this valley, and the 
barrier of sand, gravel, and clay which now separates the ponds dates from 
glacial time, or in part was contemporaneous with the sea. In several 
places in Winthrop Village and the vicinity marine fossils have been found 
at an elevation of 200 to 214 feet. Probably the plain which separates the 
upper and lower ponds was a delta-plain, deposited in the sea by a small 
glacial stream from Readfield. 

About three-fourths of a mile south of Winthrop Village, on the west 
shore of the lower pond (Lake Anabescook), is a short ridge of gravel and 
well-rounded cobbles, which at one place rises into a cone or mound 30 
feet high. This ridge has been extensively excavated by the railroad com- 
pany. Then there is an apparent gap in the system till we reach the 
south end of the lake. Here a short distance north of Kast Monmouth, on 
top of hills rising 50 to 100 feet above the lake, is a capping of glacial gravel 
one-third mile long from north to south and not quite so broad. ‘The gravel 
is a rather round-topped plain, divided along the center by a narrow north- 
and-south ravine, which does not reach to the bottom of the gravel. No 


190 GLACIAL GRAVELS OF MAINE. 


water showed in this ravine at the time of my exploration. The hill slopes 
outward in all directions, and it does not seem possible there ¢ould be so 
large an amount of erosion in such a position by either surface waters, 
boiling springs, or frost damming. The ravine is in places 10 feet deep, 
and on the lower slopes of the hill no gravel could be found that appeared 
to have come from this ravine. There is therefore no proof that the shape 
of the deposit has been materially changed since its original deposition. 

South of this gravel plain in Monmouth is a rather level country show- 
ing only very low hills. At intervals of about a half mile there are two 
other slightly round-topped deposits of nearly the same size as that near 
the lake. Both of them are also divided into nearly equal parts by north- 
and-south ravines. Seen from the high hills of southern Monmouth, these 
three ravines appear to be arranged in a nearly straight line. In neither 
case is there any pointed hill or rock in a line with these ravines, and there 
is no feature of the ground surface which accounts for them. The gravel 
and cobbles of all three of these plains are well rounded, and they all 
contain coarser matter toward the northern and central parts of the plains. 
They all are imperfect deltas of some sort. The more northern plain is 
situated at an elevation of about 275 feet, and the gravel plainly does not 
pass by degrees into the marine clays. It must have been formed where 
the glacial stream was only partially checked, since it contains fine gravel 
and coarse sand to the edge, where it ends abruptly. This indicates that 
a glacial river here flowed into a broad pool within the ice. The two more 
southern of these plains are situated in the midst of the marine clay, yet 
the transition from the plain of sand to the clay is very rapid. The current 
here was more fully stopped than at the northern plain. It is uncertain 
whether these latter are marine deltas or deltas of glacial lakes. Even if 
the glacial river here flowed into the sea, it seems to have been confined 
between ice walls at the sides. The ravines, on this theory, were formed 
in front of where the glacial torrent shot into the stiller water, the gravel 
which was carried along by it, so long as it was confined within a narrow 
ice channel, being thrown out at each side as it entered the broader water- 
way. The ravines are the channels of the rivers. 

No gravel is found for about one-third of a mile as we continue to go 
southward, and then we come to a very large mass, on which a cemetery 
is situated. In addition to sand and gravel, it contains great numbers of 


READFIELD-BRUNSWICK SYSTEM. 191 


well-rounded cobbles, bowlderets, and bowlders up to 2 feet in diameter. 
This gravel deposit is very irregular in outline, and it sends out several 
spurs both north and south. The surface is very uneven, showing a great 
variety of mounds, ridges, terraces, and shallow kettleholes. Most of the 
ridges trend north and south. It rises 40 to 80 feet above the plain of 
sedimentary (probably marine) clay which partly covers its base. It is 
about three-fourths of a mile long from east to west, and the longest spurs 
are about a half mile from north to south. These dimensions show that it 
contains a very large amount of glacial gravel. The formation is much 
finer in composition in some parts than in others, but these parts are inter- 
spersed irregularly among the areas containing coarser matter, so that it 
must be considered a compound delta or plexus of broad reticulated ridges, 
composed of a number of more or less distinct but adjacent deltas, rather 
than a single delta. So far as I could discover, none of these incomplete 
deltas pass into marine clays by degrees, and the glacial streams flowed into 
pools within the ice rather than into the open sea. 

A broad low valley extends from the foot of Sabatis Lake, in Webster, 
northeastward through Wales and Monmouth, broadening as it approaches 
Cobbosseecontee Great Pond and Lake Anabescook. This plain is all the 
way covered by clay, which in several places contains marine fossils. 
It is thus proved that there was once a continuous body of salt water 
extending from the Kennebec Bay westward to Winthrop, and thence 
southwestward to Sabatis and Lisbon, where it broadened into the Andros- 
coggin Bay of that period, which covered a large part of Topsham, 
Brunswick, Lisbon, and Durham. 

South of the plain at the cemetery in Monmouth there is a gap of 
about 3 miles, where no glacial gravel was seen rising above the marine 
clay. Then a series of low bars separated by short intervals begins not 
far north of East Wales and extends south along the eastern base of the 
high hills known as Monmouth Ridge and Sabatis Mountain. These gravel 
deposits lie in the midst of the clay-covered plain before described, and are 
partly covered by the clay. Near the south base of Sabatis Mountain the 
series expands into a very high broad ridge, becoming broader toward 
the southwest and of finer material, ending in sand, which is overlain at the 
base by the marine clay. Here the glacial streams flowed into a glacial 
lake or into the sea, but if the latter, the transition from the sand to the 


192 GLACIAL GRAVELS OF MAINE. 


clay is so abrupt as to indicate that the glacial waters were quite suddenly 
checked after entering the salt water. his delta is situated near the south- 
east angle of Sabatis Pond. Going south we find no glacial gravel rising 
above the marine clays for somewhat more than 2 miles. Then a low plain 
about half a mile long is found on the west side of Sabatis Stream, and 
then there is another gap of half a mile. A nearly continuous, low, broad 
ridge then begins and extends southward to Lisbon station of the Maine 
Central Railroad. Just north of the station it expands into a broad ridge 
or mound called Whites Hill, which rises fully 100 feet above the clay 
covering its base. Wells show this clay to be more than 40 feet deep. 
From this place southeastward to Lisbon Falls extends what is known as 
Lisbon Plain. It is a rather level plain of horizontally stratified sand and 
clay, while here and there low ridges of glacial gravel rise above the finer 
sediments which overlie it. This plain lies in the angle between Sabatis 
Stream and the Androscoggin River, and at the time the sea was expanded 
would be subject to the action of the tidal currents of both the valleys. 
On general grounds this plain might be considered a marine delta, brought 
down from the north by the glacial river we have been tracing, but its prox- 
imity to the Androscoggin makes it certain that it is in part an Androscog- 
gin River delta. East of Lisbon Falls this gravel series cousists of four 
broad ridges or plains, all situated on the north bank of the Androscoggin 
River. The first is situated about one-fourth of a mile east of Lisbon 
Falls. The second is about 14 miles east of this, and consists of two large 
and broad ridges, inclosing a deep kettlehole. The kame stuff is here very 
coarse, containing great numbers of very round cobbles, bowlderets, and 
bowlders. This deposit is half a mile long from east to west, and about 
half as broad, and rises 100 feet above the Androscoggin River. About 15 
miles farther east is another mass of glacial gravel of about the same size 
as the last named, but rather level on the top and containing few large 
stones. At the river bank it forms a steep bluff 100 feet high. After 
another interval of about 14 miles a fourth plain of sand, gravel, and cob- 
bles is found as a terrace rising only 30 or 40 feet above the Androscoggin 
River. It is not more than one-fourth of a mile long and less than half as 
broad. Its situation near the river and its level top make it resemble val- 
ley drift, from which it can readily be distinguished by a comparison with 
the drift of the river above and below this point. The stones of this gravel 


WAYNE-MONMOUTH BRANCH. 193 


terrace are much rounder than those of the Androscoge 


in flood plain or 
those in the bed of the river, and no continuous sheet of such drift is found 
along the river. This plain is situated 25 miles west of Brunswick Village, 
and I have been able to find no similar gravels east or southeast of it. I 
therefore assume this to be the end. 

In a few places this system is situated above the contour of 230 feet, 
as, for instance, in Readfield and near East Monmouth. In several places 
the tops of the ridges rise above that contour, though their bases are below 
it. This system is discontinuous from one end to the other, and by this it 
is meant that the gravels were originally so deposited. The forms of the 
gravel masses vary much and the system can hardly be classified among 
the discontinuous systems of lenticular masses. The deposits of this sys- 
tem are more hummocky and irregular in shape. Nearly all of the plains 
show some of the characteristics of the delta, but not such deltas as would 
be formed in the open sea, unless the plain near the foot of Sabatis Pond 
be such a one. 

The length of the system is 25 miles. 


WAYNE-MONMOUTH BRANCH. 


This series begins a little more than 2 miles east of Wayne Village. 
At the north end it is a small, rather straight ridge. The stones here pre- 
serve their till shapes, and the mass is quite like till in appearance, having 
a rather pellmell structure; yet close examination shows that the finest 
detritus has been washed out of the mass and the stones are a little water- 
worn. Farther south the ridge becomes very crooked and meandering and 
the stones are much more worn and rounded. There are many water- 
polished bowlders in the ridge. Within less than a mile the system becomes 
double, consisting of a continuous low ridge in a valley and a parallel dis- 
continuous series of domes or short plains forming low broad caps to a 
series of hillocks lying along the west side of the valley. Just south of 
Evergreen Cemetery there is a short gap in the series, and then another 
gravel cap on top of a low rock ridge, which ends near a small stream that 
flows southwest into Wilson Pond. No glacial gravel appeared along this 
stream or pond. Right in front of the last-named gravel deposit is the 
southwestern spur of Mount Pisgah, a high hill situated in southwestern 
Winthrop and northern Monmouth. Over this hill the road is made which 

MON XXXIV——13 


194 GLACIAL GRAVELS OF MAINE. 


leads from Wayne to North Monmouth, and it rises 150 feet while crossing 

the spur of the hill. Parallel with the road is a U-shaped ravine from 20 

to 40 feet deep on the steeper slopes of the hill, but hardly perceptible for 

a short distance near its top. The ravine is found on both the north and 

south slopes. Till shows in the bottom of the ravine, and it is strewn with 

many more bowlders—2 to 4 feet in diameter—than appear in the fields of 

till at each side. This fact indicates that this is a ravine of erosion. The 

bottom of the ravine is rather level in cross section and is from 30 to 100 

feet wide. This is an extraordimary amount of erosion in the till. But the 

drainage slopes are only about a half mile long on each side of the hill, no - 
springs or streams appeared in the valley at the time of my examination, 

and the bottom was wholly grassed over, except a small channel on the 

southeastern slope eroded by. the rains. Assuming that this canal-like. 
depression with rather steep banks is the result of erosion, the rains and 

shower streams do not seem competent for the work, judging from the 

amount of erosion accomplished by the streams of this part of the State. 

Passing a short distance down the southeastern slope, we come to a 
ridge of well-rounded glacial gravel which extends through the village of 
North Monmouth and then becomes discontinuous. ‘Two or three small 
plains of gravel take us to the plain at the cemetery southeast of Mon- 
mouth, already described. Here this tributary probably jomed the main 
river, and one or more of the northern spurs of that irregular plain may 
have been deposited by it. 

It is thus proved that a glacial river flowed from the north to the base 
of the southwestern spur of Mount Pisgah. The only trace of any con- 
nection is found on the southeastern side of this hill. It is thus made 
highly probable that a glacial river flowed up and over this hill, 150 feet 
high, along the line of that remarkable ravine. he great erosion, which 
could not be accounted for by the action of the rains, thus becomes intelli- 
gible. A glacial stream here eroded a large body of till, probably in con- 
siderable measure a part of the ground moraine. Why did it not erode 
the till at the top of the hill equally with that farther down its slope? 

The large size of the bowlders near the north end of the series favors the 
hypothesis that this was a subglacial stream. ‘There are some remarkable 
heaps of till on the southern slopes of Mount Pisgah that deserve study. 

The length of the branch is 7 miles. 


READFIELD-BRUNSWICK SYSTEM. 195 


GRAVELS NEAR SABATIS POND. 


About 1$ miles northwest of Sabatisville and a short distance west of 
Sabatis Pond is a ridge of gravel, cobbles, and bowlderets, having an 
arched cross-section. It is hardly an eighth of a mile in length, and 
appears to have no connections except a deposit on a hillock a few rods to 
the south. The gravel cap on this hillock is only 50 feet in diameter. 
Excavations near the road show that 4 to 6 feet of gravel covers the top of 
a hillock of till) The gravel is distinctly but not very much polished and 
rounded. 

The plain at the southeast corner of Sabatis Lake has already been 
referred to. The main part of this plain was deposited by the glacial 
river which flowed from the direction of East Wales and Monmouth, but a 
spur extends for one-eighth of a mile or more northwest along the lake 
toward Leeds. The Maine Central Railroad cuts through this ridge, but I 
could find no recent excavations showing the lines of stratification. ‘There 
is therefore no direct evidence as to the direction of the glacial stream 
which deposited it, except the fact that the material is coarser on the north 
than farther south. This negatives the theory that it was thrown out 
westward around the southern base of Sabatis Mountain by the eastern 
glacial river (that from Monmouth and Wales). The proof is reasonably 
strong that it was deposited by a stream from the northwest, 1. e., the 
direction of Leeds. About a mile southwest of this point a small terminal 
moraine is found in the southern part of the village of Sabatisville. The 
moraine is but little water washed and its base is overlain by the marine 
clay. It was probably formed at the foot of the ice where it confronted 
the sea. All the facts agree in proving the presence of the sea as far north 
as the foot of Sabatis Pond. 


MOUNT VERNON ESKER. 


This is a small hillside system less than one-fourth of a mile in length. 
It is found a short distance east of Mount Vernon Village. It begins near 
the southern brow of a rather flattish-topped hill, and at the base of the hill 
it ends ina small enlargement appearing to be a diminutive delta-plain, 
which incloses a depression (kettlehole?) occupied by a small peat swamp. 
It is a small deposit, but a fair type of the sidehill eskers. 


196 GLACIAL GRAVELS OF MAINE. 


CHESTERVILLE-LEEDS SYSTEM. 


This important system appears to begin about 15 miles north of Ches- 
terville Village as an osar-plain or terrace, which soon becomes a narrower 
ridge. It passes alittle to the east of Chesterville Village, and thence takes 
a nearly straight course southward to the Twelve Corners in Fayette. For 
several miles south of Chesterville Mills it takes the form of a high, broad 
ridge, with outlying plains and ridges inclosing kettleholes and some small 
lakes. It is here called Chesterville Ridge, and as it rises 50 or more feet 
above a very level plain, it forms a remarkable feature of the landscape. 
In the southern part of Chesterville the main ridge becomes lower and 
broader, and passes into an osar-plain, which continues south through a 
very low pass at Twelve Corners and thence past the Camp Ground in 
East Livermore. Then there appears to be a short gap in the system, but 
it soon begins again as a two-sided ridge of arched stratification. This low 
and broad osar crosses to the west of the Maine Central Railroad not far 
north of North Leeds, and for the rest of its course lies near that railroad. 
Near North Leeds outlying ridges appear inclosing kettleholes. South- 
ward these reticulated ridges become lower and broader, and not far north 
of Curtis Corner, in Leeds, they coalesce into a rather level plain about 
one-fourth of a mile wide, which toward the south expands in fan shape to 
the breadth of 1 mile, and the material becomes finer and finally passes 
into sand overlying clay. The sand ends about 2 miles south of Curtis 
Corner, at an elevation of about 300 feet, and from this point a plaim coy- 
ered by clay extends to Sabatis Pond, and so on, to the sea. The fan- 
shaped plain at Curtis Corner is plainly a delta. 

The problem as to the extension of this system north of Chesterville 
is complex. For years before I had worked out the diagnosis of the osar- 
plain I suspected that the plain of well-rounded gravel exteridmg along the 
valley of the Sandy River from Farmington Falls to Phillips was, in part 
at least, of glacial origin. It is but justice to add that I passed through 
this valley in 1879, before it was possible for me to distinguish the osar- 
plain from fluviatile drift. There was a glacial overflow from West New 
Portland, through New Vineyard, down a small stream that joins the Sandy 
River a mile above Farmington Village, and there was another from Kine- 
field to Strong, but in these cases the only recognizable glacial gravels were 


CHESTERVILLE-LEEDS SYSTEM. 197 


small kames near the jaws of low passes. The great size of the gravels in 
Chesterville demands a large supply of water from the north. For these 
reasons I consider it highly probable that the gravels of the upper valley 
of the Sandy River are partly an osar-plain and partly an overwash or 
frontal plain, and that this glacial river drained a large area north of Phillips 
and south of Mount Abraham. From Farmington Falls south the probable 
course of the glacial river was along the valley of Chesterville Stream. 
The relations of this osar’system to sedimentary clay and sand are inter- 
esting. From Chesterville south this system is, throughout its whole course, 
flanked and partly or wholly covered by a broad plain of sedimentary, 
bluish-gray clay, overlain by more or less sand. Toward the north this 
clay plain connects with the similar plain found in the valley of the Sandy 
River by two low valleys, one along the Chesterville Stream and the other 
lying 2 or 3 miles east of it. The broad Chesterville plain of sedimentary 
clay connects with a similar plain that borders the Androscoggin River by 
two routes, one around the northern base of Moose Hill, in Jay, and the 
other along a low pass that leads northwest from near the Camp Ground in 
East Livermore. Whether the water flowed from the Sandy River over 
into the Androscoggin or in the opposite direction is uncertain; possibly the 
flow was alternately in opposite directions, as the flood height of these 
rivers varied. South of the Camp Ground the clay plain bordering the 
osar is continuous with that of the Androscoggin Valley, as far as North 
Leeds, where a hill intervenes between the two plains. South of this point 
we have, in addition to the Androscoggin plain, two other plains covered by 
clay. One lies directly along the line of the osar, past Curtis Corner to 
Leeds Junction and Sabatis Pond. Another is from 1 to 3 miles west of 
the last named and occupies the eastern base of Quaker Ridge in Greene. 
A short distance north of Greene station this plain turns east to the head of 
Sabatis Pond. All of the clay plains just described are above the contour 
of 230 feet except at their south ends, near Sabatis Pond and Lewiston, and 
near Androscoggin Pond. Wherever I crossed them they filled the valleys 
they occupied from side to side, as if they were valley alluvium. On gen- 
eral grounds we might expect the deposition of osar border clays in a broad 
ice channel along the flanks of the gravels, but if such were deposited they 
seem to be lost in the midst of the fluviatile clays and sands that were 
deposited later. It will require some nice discriminations in order to mark 


19S eee GLACIAL GRAVELS OF MAINE. 


out in the field the limits of the glacial, fluviatile, and estuarine drift of this 
region, and to write out its full glacial and postglacial history. 

Androscoggin Pond, in Wayne, furnishes an interesting study. To 
the west of it is situated the clay plain (overlain by. sand) bordering both 
the osar and the Androscoggin River. The pond is so nearly on a level 
with the river that its outlet is called the Dead River.. In time of flood 
the water of the Androscoggin River is higher than the pond, and the flood 
rushes with violence southeastward into the lake, carrying so much sedi- 
ment that a large delta has been formed on the western shore of the pond. 
Such an overflow into the pond would be much more vigorous directly 
after the melting of the ice in the valley, when the Androscoggin River 
stood at least as high as the top of the clay plain about 50 feet above its 
present level. Under these conditions, why was there not a much larger 
delta formed on the western shore of the lake? Or, rather, why did not 
the whole south end of the pond fill up? It could not have been from lack 
of sediment, for these same waters covered many square miles to the south 
of this point with from 20 to 60 feet of clay and sand. But it is possible 
that the depression where the pond now is was originally so deep a rock 
basin that even a sheet of clay as deep as the plain of the Androscoggin 
River could not fill it up. I have not examined all parts of the shore of 
this large pond (it is about 5 miles long and 3 or 4 miles broad), but at 
several points I did not find evidence that there had been deposition to such 
a depth. A broad, open valley extends from Androscoggin Pond north- 
ward through Wayne and Fayette into Mount Vernon and Vienna. In 
late glacial time there would be a flow of ice down this valley for some 
considerable time after the general ice movement had ceased. If this flow 
was sufficiently rapid to replace the ice as fast as it was melted at the east- 
ern margin of the osar channel or afterwards by the waters of the swollen 
Androscoggin River or the sea, the place where the pond now is may have 
been covered by ice during the time of most active sedimentation. This 
will account very plausibly for the fact that the pond did not fill up. 
According to the late Hon. J. 8. Berry, of Wayne, the greatest depth of 
the lake is about 60 feet, and over most of the lake it is much less. 

A nearly north-and-south ridge of glacial gravel is found a short dis- 
tance west of Leeds Junction. It ends at the south in a series of short 
ridges separated by intervals. This series is about a mile in length. At 


CHESTERFIELD-LEEDS SYSTEM. 199 


one place this gravel has been excavated by the Maine Central Railroad 
Company. There is an interval of at least 3 miles between this ridge and 
the delta-plain at Curtis Corner, which forms the apparent termination of 
the Chesterville-Leeds system. ; 

About 4 miles southeast of Leeds Junction a large mound rises in the 
midst of the large swamp at the north end of Sabatis Pond. It is probably 
_ composed of glacial gravel. 

At various points along the shores of Sabatis Lake there are small bars 
and terraces of glacial gravel at various heights above the lake up to 100 
feet. The material is but little waterworn and forms a thin cap of semi- 
morainal yet water-washed grayel overlying the till. - It is uncertain whether 
these gravels south of Curtis Corner are any part of the Chesterville sys- 
tem. I provisionally marked them as distinct. The gravels along Sabatis 
Lake, taken in connection with the terminal moraine at Sabatisville, afford 
some prima facie evidence of a local glacier moving down the valley of 
Sabatis Lake, which is bordered by hills several hundred feet high. The 
shortness of the moraine shows that the ice movement was then confined to 
the valley. North of Sabatis Pond are two open valleys, along which the 
ice could easily flow on a descending grade to Sabatisville. One opens 
northward into Monmouth, the other extends northwestward through Leeds 
toward Wayne and Kast Livermore. After the general movement of the ice- 
sheet had ceased, on account of transverse hills, ice could still for a time con- 
tinue to flow in these favorable valleys. Such a local tongue of ice in the 
valley of Sabatis Lake would account for: (1) the terminal moarine at Sabat- 
isville; (2) the water-washed moraine stuff on the sides of the hills near the 
lake (i. e., these were formed along the margin of the local glacier); (3) the 
fact that the basin of the lake was not filled up by the clays, which may be 
due in part to the fact that the valley was filled by ice till a rather late date. 
The length of the system from Chesterville to Curtis Corner, Leeds, is 20 
miles. This portion of the system must date from late glacial time. 

I have not here explicitly classified the water drift of the Sandy River 
above Farmington Falls as an osar-plain overlain by later frontal sediments. 
The critical reader, however, who compares this system with those of the 
other valleys lying eastward at the same distance from the coast, as, for 
instance, the gravels of the Carrabassett and upper Kennebec valleys, will 
discern that the sedimentary drift of all these valleys has many features in 


200 GLACIAL GRAVELS OF MAINE. 


common and probably has a common origin. If so, a glacial river once 
flowed through the upper Sandy River Valley to near Farmington Falls, 
and thence southward, and was a part of the Chesterville-Leeds system. 
It deposited a somewhat discontinuous osar-plain along this route. Subse- 
quently, as the ice melted, a great quantity of frontal matter was poured 
out into the open Sandy River Valley in front of the retreating glacier. 
The floods now more or less washed away and reclassified the previously 
deposited glacial gravels, and flanked and covered them with later sedi- 
ments. The finer matter, being carried southward, formed the great sed- 
imentary plain that borders the Sandy River from near Farmington to its 
mouth, and also furnished the sediment for the overflows through Mercer 
and Norridgewock to the Kennebec River, also that through Chesterville 
to the Androscoggm, and thereby helped to form the broad clay-and-sand 
plains of Chesterville, Jay, Hast Livermore, Leeds, Greene, ete. In other 
words, these great clay plains situated above 230 feet are frontal plains, com- 
posed of the glacial mud poured out from the diminished glaciers which 
yet lingered in some of the larger valleys in this region and covered nearly 
all the country situated 20 to 30 miles to the north. This was the chief 
origin of the mud, no matter at what elevation the sea stood at this 
distance from the coast. At the place of deposition this fine sediment now 
forms a part of the valley sediments.’ 


FREEPORT SYSTEM. 


This is a short system appearing to begm in Brunswick near the 
southern brow of a broad hill of granite, a short distance southeast of 
South Durham. For about a mile it is a nearly continuous ridge with a 
meandering course and obscure stratification. ‘The gravel here is but little 
waterworn and has a morainal aspect. Going southward, we find the stones 
more rounded and the series becomes discontinuous, consisting of short 
ridges one-half mile or less in length and separated by intervals of varying 
length up to 2 miles. One ridge of the series is found in Freeport Village, 
near the railroad station. The size of the ridges and hummocks of the 
series decreases toward the south. The last of the series seems to be a small 
bed of gravel situated about a mile southwest of Freeport Village. Except 


‘The sea may have reached to Farmington, and these great plains be in large part fluviatile 
marine deltas. This I now (1893) consider probable. 


LEWISTON-DURHAM SERIES. 201 


at the north end, this series lies in a region covered by marine clay. Its 
length is about 5 miles. 

A small plain of gravel, cobbles, and rounded bowlders, which appears 
to have no connections, is found about 2 miles northwest of Freeport Village. 
It will be more fully described later. 


LEWISTON-DURHAM SERIES. 


This is a discontinuous series of short ridges, domes, and plains, sepa- 
rated by the usual intervals. It appears to begin as a terrace in the 
southern part of Greene, a short distance east of the Androscoggin River 
and about 75 feet above it. The gravel here is but little waterworn, yet 
plainly has had the finer detritus washed out of it. From this point the 
series continues along the left bank of the Androscoggin River through 
Lewiston to the west line of Durham, but for 2 miles in Auburn a nearly 
parallel series is found also on the right bank. One of the smaller mounds 
of this series is found in the city of Lewiston, a short distance from the 
end of the upper wagon bridge between Lewiston and Auburn. It is 
composed of well-rounded gravel and cobbles. 

The two parallel series of gravels in Lewiston and Auburn are found 
at or near the brow of the steep banks on each side of the river channel. 
These places would be favorable to the formation of crevasses in the ice, 
and the appearances indicate that a subglacial river flowed on each side 
of the valley, and that they united into one stream about a mile east of 
Lewiston. The domes of this series vary in height from a few feet up to 
100 feet. They are covered or partly covered by the marine clays as far 
north as Lewiston, and how much farther is uncertain. The lower clay at 
Lewiston contains various marine shells; the upper clay is sparingly fossil- 
iferous. The only fossil I have been able to find in the upper clay is a 
marine alga, a frond of sea lettuce, found a short distance north. of the 
Androscoggin River in Lewiston. This was at an elevation of about 220 
feet. When the sea stood at the contour of 230 feet, it would extend 2 or 
more miles above Lewiston. 

The condition of western and central Maine during the last of the Ice 
period proper and during the subsequent time when the ice was melted over 
the valleys but still lingered in the country lying to the north will, when 
fully investigated, form the basis for an interesting chapter in geological 


202 GLACIAL GRAVELS OF MAINE. 


history. In connection with the investigation of the glacial gravels, I have 
been able to gather many facts as to the periods in question. The aspect 
of the coast was then very different from what it is at present. The sea 
certainly extended up the Kennebec Valley to Madison, and up the Andros- 
coggin to a point not far north of Lewiston, and in both valleys it may have 
extended several miles farther. The Sandy River from Farmington Falls 
eastward was from 1 to 5 miles wide, and this portion of the valley was 
probably occupied by an estuary. The Sandy River at that time over- 
flowed southward, as before stated, or arms of the sea extended and joined 
the Androscoggin in Jay, East Livermore. South of Livermore Falls the 
alluvial plain of the Androscoggin was between 2 and 3 miles wide for a 
large part of its course southward to the sea. At the present day the 
highest stage of these rivers in time of flood affords far less water than then 
flowed in them. At about this time there was apparently an extensive 
overflow of the Androscoggin River southward from Canton through a low 
pass in the western part of Livermore into Turner, where it jomed a broad 
sheet of water which filled the valley of Twentymile River as far west as 
Buckfield and overflowed southward from Buckfield Village through Minot 
into a similar body of water which filled the valley of the Little Andros- 
cogein River to a point west of Mechanic Falls. A line of clays also extends 
south from Turner to Lake Auburn. This is in part osar border clay, but 
in a greater part is an overflow of the Twentymile River after the ice had 
melted. All these were probably arms of the sea. For the greater part the 
_ broad sheets which filled these valleys extended from side to side of their 
valleys. Apparently the ice had then melted in the valleys, or nearly so. 
At this time a narrow arm of the sea extended from the Fair-ground, 
Lewiston, eastward along a low valley to Crowleys Junction, where it con- 
nected with the sea in two directions, one northeastward to Sabatisville, the 
other southeastward to Lisbon. 'Tide water extended up the valley of the 
Little Androscoggin River several miles above Auburn, perhaps as far as 
South Paris. Below Lewiston the Androscoggin Bay of that period was 
from 1 to 3 miles wide, and in Durham a strait extended southward through 
Pownal and soon opened out into the bay 10 to 20 miles wide which then 
covered the valley of Royal River. The whole of the coast region of 
Maine to a breadth of from 10 to 30 miles was then submerged, except the 
higher hills, which appeared as a multitude of islands off the coast. The 


LEWISTON-DURHAM SERIBS. 203 


rivers were pouring a vast body of muddy water into the sea, and extensive 
deltas of sand and clay were being formed off the coast of that period. 
Above the sea vast rivers occupied the valleys. They were laden with 
sediment, and rapidly filled up their valleys with alluvium or valley drift. 
At first the sediment was clay, but later the floods were higher, or the 
slopes steeper, and sand was deposited by the swifter waters. This sand, 
being poured into the sea by the Androscoggin and other rivers, was car- 
ried far and near by the tidal currents and spread over the previously 
deposited marine clays. A broad area of delta sands brought down by the 
Androscogein at this time extends from Lewiston to Brunswick and 'Tops- 
ham, and almost to Bath; also from Durham southward to Yarmouth. 
The area of this delta sand is diversified by frequent dunes of blown sand. 
A small portion of the sand overlying the marme clays may be due to 
erosion of the till by the sea. But this sand is not most abundant next the 
high hills, and there is no body of beach gravel corresponding to the sand. 
It is plainly delta sand brought down by the Androscoggin, which not only 
emptied into the sea near Lewiston, but also near the south end of Sabatis 
Pond by way of Leeds. 

The Lewiston series of discontinuous domes and mounds ends near 
the west line of Durham. About 3 miles southwest of this point another 
series of mounds and broad plain-like ridges begins and extends past West 
Durham into the northern part of Pownal, where the series ends, unless a 
small ridge near Pownal Center be a connection of the series. Here, in 
Lewiston, Durham, and Pownal, are illustrated the difficulties of classifymg 
glacial gravels. According to general analogy, the gravel systems end 
in either a delta-plain or they become discontinuous and form a series of 
short ridges and domes, which become smaller and smaller toward the 
south, and the intervals between them longer and longer. The Lewiston 
series ends in the manner last mentioned near the Androscoggin, in the 
northwestern part of Durham, and the West Durham series ends in the 
same way in Pownal. These series are situated nearly in the same straight 
line, and the interval between them is less than 3 miles—facts which favor 
the theory that they are a continuation of the same system and were depos- 
ited by the same glacial river. But each series ends in a way characteristic 
of the terminations of the independent systems, and I therefore hesitate to 


204 GLACIAL GRAVELS OF MAINE. 


assion them to a single glacial river, although the same river can be 
conceived as running two independent careers at different times. 

The vicinity of Lewiston is a favorable locality for studying the dif- 
ferences between the glacial grayels and the valley drift. Only two theories 
can be admitted as accounting for the ridges and mounds of gravel and 
cobbles of the Lewiston series—they are either glacial gravel or they are 
uneroded fragments of an ancient sheet of valley alluvium. 

1. From Bethel to the sea the alluvium of the upper terraces of the 
Androscoggin Valley is in general either sand or clay. For a short distance 
below where the river has cut through ridges of till, there are limited areas 
of gravel, also at the parts crossed by glacial gravel systems or near the 
mouths of the swifter tributaries. Low terraces of sand and gravel are 
found along the banks of the river, reaching 5 or 10 feet above it, but 
nowhere below Bethel does the low flood- 
plain terrace contain any such rounded 
cobbles or bowlderets as are found in the 
ridges of the Lewiston series, except where 
crossed by osars and near the mouth of 
. Swift River. The stones of the flood-plain 
Sicsew esses terrace and those in the bed of the river 


Be 
gy are not nearly so much rounded, and many 


0 
0,0 


io : 
MELDG MONG of them have till shapes, with but little 


Fic. Aloud tues of lenticular gravel. 


rs 


modification by water action 

The two-sided ridges and mounds of gravel, cobbles, and bowl- 
derets of the Lewiston .series cover but a small part of the valley—here 
and there a dot, so to speak. If they are uneroded portions of a sheet of 
similar matter which formerly filled the valley to a height of about 100 
feet, then there has been a vast erosion of coarse matter from the valley, 
and this ought to appear as plaims of such material in Brunswick and Bow- 
doinham and along the shores of Merrymeeting Bay, where the Andros- 
cogein unites with the Kennebec. But those regions show only fine 
sediments—sand and clay. 

Two-sided ridges and domes rising 50 to 100 feet above the level 
ground on all sides of them can not be any form of beach terrace or sea 
wall. Their forms and situations make this impossible. In short, these 
gravels can not be any form of marine or ordinary fluviatile drift. 


' 
| 
: 
: 


LEWISTON-DURHAM SERIES. 205 


The length of the Lewiston series is 9 miles; that of the West Durham 
series, 5 miles. 

HILLSIDE ESKERS IN JAY AND WILTON. 

About 13 miles south of Beans Corner, in Jay, is a good specimen of 
the short sidehill systems as they appear in a region of granite rock. Four 
parallel ridges begin on the rather steep southern slope of a hill and extend 
about one-fourth of a mile southward to the base of the hill, where they 
expand into low broad. ridges and then appear to end in a dome of coarse 
matter. To the south and east are some rather level till-covered fields, and 
then the great clay-covered plain of Jay and Chesterville, but I could trace 
the glacial gravel no farther in that direction. The ridges are composed of 
a mixture of gravel and 
large stones of all sizes, 
up to bowlders 3 feet in 
diameter. The finer de- 
tritus has been washed 
away, but the stones are 
hardly more rounded 
than those of the terminal 
moraines of the local 
Androscoggin glacier in 


Gilead and Shelburne. oat ta eee aes 
FG. 22.—Stratification of lenticular gravel. a, a, very obscurely stratified 
The hillside Systems usu- portions of kame, almost pellmell in structure. 


ally become finer in composition at their south ends, where they terminate 
in a sort of delta, but in this case the ridges are composed of coarse matter, 
even to their extremities. The large size of the contained bowlders favors 
the interpretation that these ridges were deposited beneath the ice. 
Another short system begins at the top of the hill which lies directly 
south of Wilton Village, and extends for somewhat more than a mile south- 
ward, into Jay, on the slopes of a long hill. Its course lies along the bot- 
tom of a ravine 100 to 150 feet wide, which is bordered by steep banks of 
till 10 to 80 feet high. The gravel forms a terrace lying against and upon 
the till which forms the eastern bank of the ravine. On the west side the 
bottom of the ravine is quite level and covered with soil finer in composi- 
tion than the surface till of the surrounding country. It is either a very 
clayey till or a sedimentary clay into which some tillstones have been 


206 GLACIAL GRAVELS OF MAINE. 


washed by the rains or other means. At the base of the hill (after a fall of 
about 100 feet) the gravel spreads out into a narrow fan-shaped series 
of several ridges situated side by side. These ridges extend a short dis- 
tance out into the valley of a small stream which flows southwestward into 
the Androscoggin River. This valley is covered by a sheet of sedi- 
mentary clay and coarse sand to a breadth of one-fourth of a mile. These 
sediments overlie the glacial gravel ridges. On the south they are con- 
tinuous with the high alluvial terraces of the Androscoggin. 

The ravine on the side of the hill must be accounted for. The till of 
this portion of Franklin County is collected into a great number of long 
lenticular masses with smooth outlines, and is remarkably free from steep 
ridges or hummocks or depressions. This ravine has every appearance of 
having been cut into the deep sheet of till which covers the hillside. No 
stream flows in this ravine except in time of rains, and the ravine reaches 
to the top of the hill. The ridges at the bottom of the hill have steep 
slopes on both sides, and could not be formed as a delta at its base by an 
ordinary surface stream eroding the till on the hillside and sweeping the 
eroded matter down into the valley. Usually the glacial gravel is piled 
above the surrounding level, and there is no evident depression showing an 
erosion of the till, betraying where the kame stuff came from. But here, 
as in several other places, a channel with steep lateral banks is cut into the 
till. A fair inference from all the facts is that a stream flowing between ice 
walls here flowed down the hill and eroded the ravine in the till and carried 
the material down into the valley. The terminal ridges must have been 
formed between ice walls. Beyond the ridges the plain of alluvium in the 
valley may be in part composed of the finer sediment brought down by 
this small glacial stream, if the stream dates from a late period when the. 
ice was retreating up the valley, as was probably the case. 


CANTON-AUBURN SYSTEM. 


A broad mountain cirque between high hills is situated in Weld, Car- 
thage, Mexico, and Dixfield. This valley is dramed southward into the 
Androscogein River at Dixfield. Considerable alluvium is found in the val- 
ley, most of which appears to be valley drift, i. e., frontal overwash, but 
with some signs of an osar-plain along the axis of the valley; and the same 
can be said of the valley of Swift River m Byron, Roxbury, Rumford, 


CANTON-AUBURN SYSTEM. 207 


and Mexico; and perhaps there should be added the Androscoggin Valley 
from the mouth of Switt River to Canton. There has been a large amount 
of erosion along the Androscoggin and Swift rivers, and this makes it 
doubly difficult to discover what was the original condition. 

A well-developed osar-ridge begins not far from the Androscoggin 
River at Gilbertyille (Canton Point), and passes southward through the 
wide plain covered by sedimentary clay and sand which here borders the 
Androscoggin on the south. It passes about half a mile east of Canton 
Village, and then ascends the valley of Bog Brook to its source at a small 
pondin Livermore. In this valley the gravel takes a somewhat unusual form. 
A two-sided ridge is found along the axis of the valley, bordered on each side 
by a ravine of erosion, while on each side of the valley is a level terrace of 
fine gravel. The central ridge consists of gravel with cobbles and bowl- 
derets, all very much rounded. It rises 10 to 20 feet above the terraces at 
the sides of the valley. Evidently a glacial stream at one time flowed in a 
rather narrow channel in the midst of the valley, and in this narrow chan- 
nel was deposited the central ridge of coarse matter. Later the channel 
widened until it extended nearly or quite across the valley, and in this 
broad channel the finer gravel was deposited as a plain extending from the 
central ridge to each side of the valley. The current in the broad channel 
was not so rapid as in the narrow one, and the gravel was finer and did not 
reach to so great a height as the original osar. Finally valleys of erosion 
have been excavated in the osar-plain along each flank of the osar. 

In several places the terraces along the sides of the valley can be seen 
to overlie till. Many bare ledges appear in the southern part of the pass, 
as if the till had been washed away by the glacial river. The top of this 
pass is so level that for a considerable distance we find a stream flowing 
northward on one side of the osar ridge and on the other side a stream 
flowing in the opposite direction. 

On the west and southwest sides of Brettuns Pond, at Livermore Post- 
Office, the gravel takes the form of a narrow plain of reticulated ridges and 
hummocks of gravel, cobbles, and bowlderets. Extending from this plain 
eastward around the south end of the pond is a rather level plain’ composed 
of gravel on the west but becoming sandy toward the east. It is about 
one-third of a mile in diameter, and is evidently a delta-plaimm. It lies 
between Brettuns Pond and the valley of Martins Stream. This valley is 


208 GLACIAL GRAVELS OF MAINE. 


widely covered by sedimentary clay from Livermore Center eastward to 
Livermore. The currents which deposited the delta south of Brettuns 
Pond must have flowed for near a mile along the west and southwest sides 
of the pond, bordering it with high, steep banks of gravel, cobbles, and 
bowlderets. If the area where the pond now is had been bare of ice at 
the time these waters flowed south from Canton, the delta would have 
been formed where the pond now is. The facts indicate that the valley of 
Martins Stream was occupied by a glacial lake or other body of water at 
the time this delta was formed, while the area where the pond now is must 
have been occupied by ice. The finer sediment brought down by the 
glacial stream passed beyond the delta of gravel and sand, and furnished 
the clay which covers this valley. 

A rather level osar-plain, from one-eighth to one-half of a mile wide, 
extends along the valley of Martins Stream southward nearly to the 
Twentymile River. Between Livermore and North Turner the plain has 
been irregularly eroded so as to leave a marginal terrace on each side of 
the valley and a ridge, or, rather, series of ridges arranged as a single line 
in its midst. These ridges appear as narrow islands in the midst of the 
artificial pond (produced by the dam at North Turner), which now occupies 
the valleys of erosion on each side of the central ridge. The central ridge 
here has the same height as the marginal terraces, except where it has been 
reduced by erosion. South of North Turner the osar-plain is bordered by 
a wide plain covered by sedimentary clay, overlam by some sand. This 
alluvial plain is connected with the plain of sedimentary clay that covers 
the valley of Twentymile River by two lines of clays, one southward 
down the valley of Martins Stream, the other southeastward past the west 
side of Pleasant Pond and then by a low pass to Bradford Village (Turner 
Center). I could find no glacial gravel. along the last-named route, and 
infer that this large area of fine sediment was not deposited in a broad 
osar channel, but at a time when the lowlands were all bare of ice and 
covered with water, probably either fluviatile or estuarine. 

The osar terrace becomes finer as it nears the Twentymile River, 
and thus shows some of the characters of the delta-plain. It appears 
to be interrupted for a half mile or more near Twentymile River, but 
soon begins again as a series of low reticulated ridges or plains from 
one-fourth to one-half of a mile broad. The reticulated plains extend 


CANTON-AUBURN SYSTEM. 209 


southward along a low pass. They inclose several lakelets, some without 
visible outlets. ‘Toward the south the ridges coalesce into a level plain, the 
materials of which become finer, the gravel passing by degrees into fine 
sand, and this into sedimentary clay about a mile north of the northeast 
angle of Lake Auburn. This clay extends along the east side of the lake 
and thence to Auburn and Lewiston, where it is plainly marme. A little 
silt or clay is found in the valleys of the small brooks which flow into Lake 
Auburn, which is probably valley or lake drift. With these insignificant 
exceptions, the only clay found along the shores of the lake is that found 
along the northeastern side, where a plain of fine blue clay rises 30 feet 
above the lake and apparently forms part of the barrier that holds it back. 
If Lake Auburn was bare of ice or was occupied by an open arm of the 
sea at the time this clay was being laid down, the clay ought to have 
extended farther west, probably all around the lake. The water which 
poured south from Turner was certamly muddy, as is shown by the great 
depth of clay at the northeast angle of the lake. This makes it highly 
probable that the clay was deposited in a broad channel within the ice at a 
time when the area which Lake Auburn now occupies was covered by ice. 

No gravel rises above the clay for about 2 miles, and then we find a 
rather level gravel plain near the southeast angle of Lake Auburn. It is 
about a mile long and more than half as broad. The gravel, cobbles, and 
bowlderets of which it is composed at its north end are not much water- 
worn, and often have almost a till shape. ‘Toward the south and east the 
material is somewhat finer and the plain appears to be a delta deposited 
either in a bay of the sea that was inclosed between ice walls or in a glacial 
lake. About half a mile south of this is another similar one. It ends in 
steep banks on all sides except one, where it lies like a terrace against a 
hill. This plain is only about one-fourth of a mile in diameter, and becomes 
sandy on the south and east sides, and is thus shown to be an incomplete 
delta. 
South of this point I have been able to find no glacial gravel for about 
8 miles. The system ends on a hill overlooking the valley of the Little 
Androscoggin. The system dates from a time when the sea had advanced 
up the valleys of the Androscoggin and Little Androscoggin to a point 
some distance west of Auburn. ‘The ice still lingered to the north. Three 


delta-plains were formed in Auburn during the flow of this large glacial 
MON XXXIV-——14 


210 GLACIAL GRAVELS OF MAINE. 


stream, and perhaps a fourth was afterwards formed in Turner north of the 
Twentymile River. For many miles this great osar river flowed in a chan- 
nel one-eighth to one-half of a mile wide. In this channel was deposited 
a level plain of rather fine gravel of the type which I have named the osar- 
plain. Whenever the system expands into plains of reticulated midges the 
material is very coarse. The very great size of the glacial river which 
flowed south from Canton makes it highly probable that it drained the val- 
leys lying north and northwest from it, including Swift River. If so, the 
original gravels have been much disguised by later sediments. Indeed, we 
might expect that during the retreat of the ice there would come a time 
when the ice was melted over the Androscoggin Valley but still lingered 
toward the north, and overwash or frontal plains would at this time be 
brought down into the main valley and cover out of sight much of the 
earlier sediment. 
The length of the system from Canton to Auburn is about 25 miles. 


NOTE ON THE ANDROSCOGGIN VALLEY. 


For about 60 miles from Gorham, New Hampshire, to Jay, the direc- 
tion of the Androscoggin’ River is a little north of east. It is a valley of 
preglacial erosion excavated in highly crystalline rocks, chiefly granite. 
On each side of the river the hills rise steeply, becoming higher as the 
White Mountains are approached. The river is bordered by a plain of 
valley drift, which for most of its course is less than half a mile in breadth, 
but here and there spreads out into much broader intervals, 1 to 3 miles 
wide. Such a plain is found in Canton. About 3 miles east of Canton the 
river has cut through a sheet of till 70 feet thick. This body of till 
dammed the river in the Valley Drift period and formed a lake where the 
broad Canton intervale now is. It is probable, but not certain, that this 
raised the level of the Androscoggin sufficiently to cause an overflow south- 
ward to Livermore along the Bog Brook Pass. As already noted, the 
valley drift of the Androscoggin is noticeable for its fineness over most of 


the course of the river. 
HILLSIDE ESKERS IN HARTFORD. 


Whitney Pond lies a short distance southwest of Canton Village. 
About a mile north of this pond, on the road from Canton to Sumner, are 


PERU-BUCKFIELD SYSTEM. PAYA 


two short systems of sidehill kames or eskers. They are situated in small 
north-and-south valleys which descend steeply toward the south. The 
ridges begin on the hillside, and after descending about 100 feet to rather 
level ground, they end within a mile in small delta-plains. At their north 
end the ridges do not have the smooth and arched cross section so common 
to kame ridges found near the present sea level, but they have the steeper 
lateral slopes and the irregular heaping characteristic of the lateral moraines 
of a local or valley glacier. The material has been but little polished by 
water, yet the finer drift has been washed out of it. The two systems are 
only about a mile apart. The western system consists of three parallel 
ridges which become confluent in the terminal plain. 


PERU-BUCKFIELD SYSTEM. 


Worthley Pond, Peru, lies in a narrow valley bordered by steep, high 
hills. The outlet of the pond flows northeastward into the Androscoggin 
River at South Peru. South of the pond the valley narrows so as to form 
an almest V-shaped pass through the high hills which le not far south of 
the Androscoggin River. The highest part of this pass is situated only a 
short mile south of Worthley Pond and about 100 feet above it. South of 
the pond, in the bottom of this narrow valley, are several short ridges of 
sand separated by gaps. Only a small brook flows in the valley, and it is 
quite incapable of depositing ridges such as these, in respect either to 
form or to size. Lying across this part of the valley, or forming irregular 
terraces along the lower slopes of the bordering hills, are numerous piles 
and heaps of sandy till which have the appearance of moraines of a local 
glacier. Probably a tongue of ice projected south through the pass in late 
glacial time and left these moraines during its retreat northward. During 
the retreat of the ice front down the northern slope, a small lake would 
naturally form between the ice and the hill to the south. The drainage of 
the local glacier would pour into this small lake and then overflow south- 
ward over the col. If a large stream flowed into such a lake, the whole 
valley ought to be deeply covered by a lake delta. On the contrary, the 
sand and fine gravel are found in the form of several isolated ridges. This 
seems to indicate that the sand ridges were deposited by small streams in 
channels within the ice, and that after the formation of the lake at the ice 
front there was either little sediment or the drainage flowed northeastward 


212 GLACIAL GRAVELS OF MAINE. 


to the Androscoggin. I could find no proof that these sand ridges were 
uneroded portions of a delta that once filled the valley. 

No kame material was found for a short distance near the top of the 
pass, and then begins a series of low ridges and terraces of fine gravel con- 
taining but few large stones, and those are but little polished by water. In 
numerous places these deposits could be seen to consist of a thin sheet of 
gravel (2 to 5 feet thick) overlying the till. All these facts combine to 
prove that the glacial stream that flowed south through the Worthley Pond 
Pass was very small, compared with the mighty rivers which flowed out of 
the Androscogein Valley at Canton and Rumford. The system follows the 
valley of the main east branch of Twentymile River to Sumner station 
(Sumner Flats), and then its course lies near the railroad to a point near 
Buckfield Village. The gravel appears as low, rather level-topped ridges, 
like a narrow osar-plain, except that they inclose some shallow kettleholes. 
Often these plains appear like terraces on the sides of the valley, and 
erosion of the central parts of the plain by the stream often increases this 
resemblance. The system is somewhat interrupted by short gaps north of 
Sumner station. South of that point the separate ridges coalesce more and 
more, and not far north of Buckfield the system passes into a delta-plain 
one-fourth to one-half mile wide. The sand of the delta passes by degrees 
into the clay which covers the valley of the Twentymile River all the way 
from its mouth to a point several miles ahove Buckfield. At a few points 
not far south of Sumner excavations showed that a number of low ridges 
had first been deposited in a separate, narrow channel, bordered by ice 
walls. Subsequently the depressions between the ridges were filled up so 
as to make of the whole a level-topped plain. Probably the tops of the 
original ridges were in part washed away by the broad body of water 
which at the last swept over the whole breadth of the gravel system, and 
may have furnished part of the material to fill up the depressions. This is 
a sort of structure to be anticipated for the osar-plains, but in this case the 
plain extends across the valley from side to side in such a manner as to 
make it difficult to judge whether this plain was deposited in a broad 
channel within ice walls or in the open valley after the ice had melted. 
Even if the upper part of the plain be valley drift of less age than the ice 
occupancy of that region, the underlying ridges are plainly contempo- 
raneous with the ice occupancy. 


WEST POLAND-SUMNER SYSTEM. DIB 


The delta-plain northeast of Buckfield Village has been deeply eroded 
by streams and springs. At one place a long ridge has been left uneroded. 
It is locally known as the ‘‘Whalesback.” On the surface it appears to be 
composed of nearly horizontally stratified sand and gravel like the rest of 
the delta, yet there must be some reason why this portion of the plain has 
resisted erosion, and it may be there is a ridge of coarse kame stuff along 
the axis of this “Whalesback.” Hvyidently this delta dates from a late period, 
when the ice had melted as far north as this place. 

The apparent end of this system northeast of Buckfield is only about 
a mile from the West Sumner-Poland system. It is therefore possible— 
perhaps probable—that they were at one time connected, but thus far I am 
unable to prove it. The Peru glacial river may have joined that from West 
- Sumner by flowing southwest from the above-mentioned delta-plain through 
Buckfield Village or along a very low valley situated about a mile farther 
east. These valleys are all so deeply covered by sedimentary clay that 
only large deposits of glacial gravel would rise above the surface. This 
clay is probably of estuarine origin. | 1 

The length of the system from Worthley Pond to Buckfield is 13 miles. 


WEST SUMNER-POLAND SYSTEM. 


This system appears to begin about a mile south of West Sumner, in 
the form of an osar-ridge which follows the valley of the west branch of 
Twentymile River for several miles and then expands into a delta-plain a 
short distance west of Buckfield Village. From this point a broad, low 
valley extends southward to Mechanic Falls. Along this valley the railroad 
is constructed. The bottom of the valley is covered with sedimentary clay, 
continuous on the north with the clay of the valley of Twentymile River 
and on the south with that of the Little Androscoggin Valley. A series of 
low ridges, terraces, and deposits of glacial gravel resembling the broad 
osar is found along the valley its whole length. Near Buckfield the gravels 
skirt the base of the high hills lying west of this valley, near East Hebron 
they lie in the midst of the pass, and at West Minot they are on the west 
side again. As we approach Mechanic Falls the gravels rise out of the 
valley and are found on the slopes of the hills on the east side. There are 
several apparent short gaps in the series. The intervals are more frequent 
toward the south and the deposits become narrower and finally form simple 


214 GLACIAL GRAVELS OF MAINE. 


eskers not at all plain-like. Near the Little Androscoggin River there is 
apparently a long interval of 2 miles where there is no gravel. About 2 
miles east of Mechanic Falls is a sand-and-gravel plain in Poland, which 
extends for more than 2 miles southeastward near the line of the Grand 
Trunk Railway. The plain becomes finer on the east and south edges, and 
passes by degrees into sand and at last into the clay which covers the 
valley of the Little Androscoggin from Auburn many miles west. These 
plains in Poland are a delta, but it is uncertain whether they were formed 
in a glacial lake or in the broad body of sea water which subsequently 
covered Little Androscoggin Valley. 

Subsequent to the melting of the ice there was an overflow from the 
valley of the Little Androscoggin southeastward along a low pass, past 
Danville Junction. There are several mounds of true glacial gravel in the 
valley of Royal River in New Gloucester. hese are properly situated 
to be branches of either the Canton-Auburn or the West Sumner-Poland 
system, but I have been able to trace no connection between them, although 


the Danville Junction Pass is a favorable route for a glacial overflow. It 


thus appears that both the long systems named end in deltas near the Little 
Androscoggin River, and are therefore a feature of the later history of the 
Ice age, when the ice had receded so far north that this valley was covered 
by an arm of the sea or by an estuary. 

The length of the system from West Sumner to Mechanic Falls is 
12 miles. 

BRANCHES IN HEBRON AND NEAR WEST MINOT. 

In the northeast part of Hebron is a short series of hillside kames 
situated in the valley of a small brook named Bicknells River. They 
expand toward the bottom of the hill into small terrace-like plains. One 
of these plains is one-eighth of a mile in diameter. It consists of three 
rather level terraces, each rising 6 to 10 feet above the next below it. The 
gravel is but little waterworn. The general course of the series is south- 
east, and the terminal plains are only about a mile from the main system 
at East Hebron. It is uncertain whether this is a local series or whether it 
was deposited by a tributary of the main glacial river. 

About three-eighths of a mile north of West Minot is a series of kames 
which begins on the side of a hill and extends down the hill for a short 
fourth of a mile to join the main system in the valley. 


U. S. GEOLOGICAL SURVEY 


MONOGRAPH XXXIV PL, XV 


A. MOUND OF BOWLDERS FORMING THE SOUTH END OF HILLSIDE ESKER; ABOUT 2 MILES SOUTH OF BEANS 
CORNER, JAY. LOOKING EAST. 


The remainder of the esker extends northward up the hill at the left. 


B. HILLSIDE ESKER ENDING IN GRAVEL TERRACES; HEBRON, LOOKING NORTH, 


YARMOUTH-CAP#H ELIZABETH SYSTEM. 215 


HILLSIDE ESKERS IN OXFORD COUNTY. 


There are several short hillside osars in Paris, Woodstock, Sumner, 
and other hilly parts of Oxford County. A particular description of them 
is omitted, since they are so small as not to illustrate the mode of forma- 
tion of this class so well as the larger deposits already described. 


YARMOUTH-CAPE ELIZABETH SYSTEM. 


This is a discontmuous system, consisting of rather level plains up to 
one-fourth mile in breadth, and of low, broad ridges with arched cross see- 
tion. The intervals between the successive deposits are nowhere more than 
about 1 mile. The gravels of this system are usually found on the tops of 
low hills as a rather thin cap overlying the till. The system appears to 
begin as a low plain of gravel situated not far north of Yarmouth Village. 
In Yarmouth Village it takes the form of a small plain of gravel and very 
round cobbles, and then there is a space of about a mile where the gravel 
does not appear above the marine clay. Not far north of Cumberland 
Post-Office the gravel begins again, and the intervals between the succes- 
sive ridges are then very short for several miles. The shore road (Fal- 
mouth Foreside) follows the course of the gravel series as far south as the 
marine hospital near Portland. Near this point is a small kame situated a 
short distance west of the main system (near an old rolling mill and 
foundry), which was probably deposited by a small lateral tributary. The 
next gravel deposit of the series is on the top of Munjoy Hill, in the 
eastern part of Portland, as a sheet of gravel and cobbles capping a lentic- 
ular mass of till. A discontinuous series of gravel plains extends south- 
ward through Cape Elizabeth to within a short distance of the sea at 
Bowery Beach and Two Lights. I could discover no sign of the system 
having at any time extended south of this pomt into the sea. 

As most of the gravels of this series are on hills less than 100 feet 
high, they were in exposed situations while covered by the ocean, and 
much of the glacial gravel has thereby been washed away from the top of 
the ridges, often being spread over the adjacent fossiliferous marine clays. 
Although these plains externally resemble delta-plains m several of their 
features, yet the original structure has so far been modified on the surface 
by the sea that it is unsafe to assert that the glacial gravel was originally 


216 GLACIAL GRAVELS OF MAINE. 


deposited by glacial streams in the sea over the marine clays. This can be 
established only by excavations reaching below the beach gravels. 

In Portland and Cape Elizabeth the gravels of this system are suspi- 
ciously near those of the great Androscoggin Lakes-Portland system. No 
connection is yet proven between them, and they are therefore classified as 
distinct systems. The stones of this series are in general well rounded, 
though not so much worn as in many of the longer systems. 

The length of the system is 18 miles. 


ANDROSCOGGIN LAKES-PORTLAND SYSTEM. 


This is a large and important discontinuous system of peculiar type 
and affording many interesting problems for vestigation. For convenience 
it will be referred to as the Portland system. 

The course of the Androscoggin River is circuitous. Its head waters 
flow west into New Hampshire, and this part of its valley is a gently roll- 
ing plain from 5 to 20 miles wide. In this plain is situated a series of large 
lakes, which may be termed the Androscoggin Lakes. From Gorham, New 
Hampshire, the river turns eastward into Maine again, and this part of its 
valley is bordered on each side by high hills, which thus separate it from 
the valley of the upper Androscoggin as well as from the valleys of Crooked 
River, the Little Androscoggin, and other streams flowing southward. From 
the region of the Androscoggin Lakes several low passes lead through the 
high hills, one southeastward from Umbagog Lake along the valley of the 
west branch of the Ellis River, and another from Lake Molechunkemunk 
southward down the Swift River. I have not explored these passes. The 
valleys of both the streams just mentioned contain much alluvium, which 
may wholly or in part be an osar-plain or frontal plain. A third pass leads 
from Rangely Lake southeastward down the valley of Sandy River. The 
highest part of the pass is 205 feet by aneroid above Rangely Lake. I 
could find no glacial gravel along this pass. The lowest of all the passes 
leads from Lake Welokennebacook southward along Black Brook to 
Andover. This I will name the Black Brook Pass. 

An interrupted gravel ridge begins on the west shore of Lake Moose- 
lookmeguntic and follows that shore to the outlet of the lake (here running 
east and west), when it crosses to the south shore and thence follows the 
east shore of Lake Welokennebacook for some miles, when it appears to 


a 


ANDROSCOGGIN LAKES-PORTLAND SYSTEM. | Die 


eross the lake obliquely—at least the ridge soon appears on the western 
shore and continues thus to the south end of the lake, where it forms a 
prominent two-sided ridge. The region lying south and southeast of the 
lake is so low that only a few feet of digging would be required to drain 
the lake southeastward down Black Brook. I am informed that in time 
past it has repeatedly been proposed to cut a canal at this place in order to 
use the water for lumbering purposes on Black Brook and the Ellis River. 
One branch of Black Brook takes its rise within a half mile of the foot of 
the lake. The osar continues southeastward along the broad and level val- 
ley of Black Brook for about 3 miles, sometimes broadening into a plain 
resembling an osar-plain in appearance. It then enters a narrow V-shaped 
pass where the hills rise steeply, almost precipitously, on each side up to 
near 1,000 feet. The glacial river flowed through this pass, but in its nar- 
row part I saw no glacial gravel for a short distance. It can hardly be 
expected that any but the larger stones and bowlders would be left by the 
stream in the narrow gorge, and if there were any such they have been 
covered out of sight by débris that has fallen from the high cliffs. South 
of the narrow pass Black Brook has for several miles a fall of 50 feet or 
more per mile, and here most of the gravel was swept away by the force of 
the glacial river. Approaching Andover the slopes become gentle, and then 
for 3 or 4 miles the valley is covered with a hummocky plain which soon 
becomes nearly horizontally stratified. This plaim is composed of coarse 
gravel, cobbles, ete., at the north, and passes by degrees into sand at the 
south. It fills the valley from one side to the other and is of varying breadth 
up to nearly a mile. The valley of the Ellis River in Andover forms a 
broad valley or mountain cirque several miles in diameter, surrounded on 
all sides by high hills, except on the south. Into this rather level plain 
pour the Black and Sawyer brooks, also the east and west branches of the 
Ellis River, all uniting not far south of Andover to form the main Ellis 
River. Sedimentary plains of gravel, sand, and silt extend up all these val- 
leys for a mile or more. Part of these plains must have been brought 
down by these streams as fluviatile alluvium, yet the alluvium is so abun- 
dant near the mouth of Black Brook as to suggest the theory that the gla- 
cial river here flowed into a lake which extended up the tributary valleys. 
The cause of such a lake will be discussed presently. 

The valley of the Ellis River narrows near South Andover, and from 


218 GLACIAL GRAVELS OF MAINE. 


there to Rumford is from one-fourth to one-half of a mile wide. It isa 
U-shaped valley bordered by high steep hills. The fall of the stream per 
mile is very small. A plain of well-rounded glacial gravel is found im the 
valley all the way from South Andover to Rumford Point. For several 
miles it lies as a level osar-plain on the east side of the valley, but for 2 
miles north of Rumford Point it is on the west side and takes the form of a 
plexus of reticulated ridges inclosing kettleholes and a lakelet. The fact 
that this gravel plain does not extend across the whole valley is proof that 
the gravel is not valley drift but is of glacial origin. Along with the 
gravel are many cobbles and well-rounded bowlderets, and the slope of 
the Ellis River is here so gentle that it is impossible to accept such coarse, 
well-rounded matter as ordinary stream wash. The portion of the valley 
not occupied by the gravel plain is covered to a considerable depth with 
silt and clay. The base of the gravel plain appears’ to underlie the clay, 
but in places along the margin of the plain the gravel can be seen to over- 
lie the clay. The great breadth of the level portion of the Ellis River 
Valley as compared with the drainage basin makes it certain that the fluvi- 
atile drift would be fine and the river currents comparatively gentle, even 
in time of flood. This makes it more probable that the deposition of the 
gravel overlying the clay took place in a broadened osar channel than that 
it was the work of the Ellis River after the melting of the ice. 

For about 3 miles from Rumford Point to the mouth of the Concord 
River there are occasional low ridges and hummocks of gravel on the west 
side of the Androscoggin River. They rise out of a low terrace of erosion 
and externally appear like uneroded portions of the plain of valley drift 
which originally must here have bordered the Androscoggin. But exam- 
ination shows that they are composed of gravel, cobbles, and even bowl- 
derets—much coarser matter than is contained in the alluvium of this part 
of the Androscoggin Valley. They are therefore glacial gravel. It is thus 
proved that the course of the glacial river crossed the Androscoggin River 
at Rumford Point. If the osar-plain was originally deposited continuously, 
it has since been eroded by the river. This must have happened since the 
Valley Drift period, for the upper alluvial terraces of the valley for many 
miles below this point do not contain gravel similar to that of the osar- 
plain. For a short distance north of the mouth of Concord River a two- 
sided ridge of well-rounded gravel and cobbles lies parallel with the 


a a ee 


ANDROSCOGGIN LAKES-PORTLAND SYSTEM. 219 


Androscoggin River, which here is flowing southeastward. The gravel 
soon turns southwest and ascends the valley of the west branch of the 
Concord River through Milton and Bethel to the top of the divide near 
North Woodstock, which is fully 125 feet above Rumford Point, and per- 
haps as much as 140 feet. From the Androscoggin River to North Wood- 
stock this valley affords an instructive study. The average slope is not 
far from 25 feet per mile. The bottom of the valley was once occupied 
by an alluvial plain from one-eighth to near one-half of a mile in breadth. 
The osar ridge near the mouth of the Concord is lost in the plain of finer 
sediments soon after it leaves the Androscoggin River. South of this point 
a ridge is found along the axis of the valley. It is from 10 to 60 feet m 
height, and is locally known as the “Whalesback.” Both sides of the valley 
are bordered by terraces having nearly the same height as the central ridge, 
but composed of somewhat finer drift. Near the Androscoggin River the 
material is sand. Going southward, it becomes coarser until, at North 
Woodstock, we find only coarse gravel, cobbles, and bowlderets. Both the 
central ridge and the lateral terraces are usually bordered by rather steep 
banks. They are simply uneroded portions of the original plain which 
extended across the valley. Two valleys of erosion have been formed, one 
on each side of the central ridge. These erosion valleys, where observed, 
do not cut down to the till, hence the osar-plain must have been originally 
of great depth. The valley is only about 8 miles long, and the small brook 
that flows in it does not receive any large tributaries. It is quite too 
small to have deposited, even in the highest floods, such a gravel plain as 
once filled the valley. Indeed, at first it seemed to me surprising that it 
could have eroded the two large valleys on each side of the ‘‘Whalesback.” 
It was not until I had studied the remarkable erosive power of boiling 
springs that I could assign any physical cause for so great an erosion in so 
short a valley. 

The alluvial terraces of the Androscoggin Valley rise from 30 to 50 
feet above the river at the mouth of the Concord. The Androscoggin at the 
time it stood at its highest level must have backed up the valley of the 
Concord for 2 miles or more, and would fill that valley with more or less 
river alluvium. At North Woodstock the gravel rises 70 or more feet above 
the highest terrace of the Androscoggin at Rumford. It is thus proved 
conclusively that the gravel along the North Woodstock Pass was not 


220 GLACIAL GRAVELS OF MAINE. 


deposited by an overflow of the Androscoggin River after the melting of 
the ice. Only an ice dam at Rumford could cause an overflow up the 
valley of the west branch of the Concord and over the col at North 
Woodstock. 

_ The following is the probable history of this interesting valley: First, 
a glacial river flowed southwestward through the North Woodstock Pass in 
a narrow channel along the axis of the pass. This was bordered on each 
side by ice walls, and in the channel was deposited an osar-ridge. Subse- 
quently this channel gradually broadened, and in the broad channel was 
deposited an osar-plain. At length a time came when the channel extended 
from side to side of the valley, and the osar-plain thus came to resemble a 
plain of valley drift in its external form. The broader the channel became 
the less rapid, on the average, was the glacial river and the finer were the 
sediments deposited by it. The erosion of the plain has proceeded more 
rapidly in the medium gravel than in the very coarse gravel, of the central 
part of the valley or in the finer sand and gravel at the margins. Now a 
dam of 125 feet at North Woodstock would flood back the water in the 
broad osar channel for many miles up the valley of the Ellis River. If 
the channel was open on the top to the air, or for any reason the broad 
osar river was not confined within the ice under high hydraulic pressure, 
the dam would cause the glacial river to form practically a lake one-eighth 
to one-half mile wide, extending from North Woodstock to Andover, where 
it would be at least 50 feet deep. The glacial river pouring from the north 
down Black Brook would deposit in this dammed osar-plain channel or 
back-water lake the plains near Andover Village which so much resemble 
lake deltas. In this long reach of quiet water would be deposited the 
fine clays of the Ellis Valley that border the narrower osar-plain. The 
osar-plain of the Ellis Valley had been deposited in still earlier times when 
the channel of the glacial river was not so broad as that of the later osar 
border clay. It is also possible that the sedimentary drift near Andover is 
in part frontal matter. 

The highest part of this pass is a short distance north of North Wood- 
stock. Here a small brook takes its origin and flows southward along a 
gentle slope to Bryants Pond. The osar-plain continues in this valley and 
the material becomes coarser, and near Bryants Pond contains very round 
bowlders 2 and even 3 feet in diameter. Here the plain becomes a plexus 


MONOGRAPH XXXIV PL. XVI 


U. S. GEOLOGICAL SURVEY 


SF 
me 


AR) 
. 


3 hed) 
aA 
eS 


BROAD OSAR PENETRATING A LOW PASS; WOODSTOCK. 


me 


‘ 


ANDROSCOGGIN LAKES-PORTLAND SYSTEM. 221 


of two or three broad ridges, inclosing one deep and symmetrical kettlehole, 
besides several shallower basins. The gravel skirts the eastern border of 
Bryants Pond and then it follows the valley of the Little Androscoggin 
River for many miles southward. 

South of Bryants Pond we have a very difficult problem, i. e., to 
distinguish an osar-plain from valley drift on a southern slope where the 
glacial river flowed in the same direction as the ordinary river which after- 
wards flowed in the valley. It thus becomes necessary to state the facts 
from which a conclusion may be drawn. 

1. The gravel plain which extends from Rumford to North Woodstock, 
and so on to the south end of Bryants Pond, is, without doubt, of glacial 
origin. The ice must have covered the Androscoggin Valley or the water 
would not have flowed southward over the divide at North Woodstock. 
No geological fact can be more certain than that a mighty glacial river, 
large enough to assort and polish the gravel, cobbles, bowlderets, and 
bowlders of a plain one-eighth to one-half of a mile wide, and that, too, on 
an up slope of 25 feet per mile, flowed southward over the North Woodstock 
divide and thence to the south end of Bryants Pond. Such a river as this 
ean not disappear by accident, and a river capable of doing so great an 
amount of work on an up slope would do still more on a down slope. 

2. The osar-plain borders Bryants Pond for about three-fourths of a 
mile. If the basin where the pond now is had been bare of ice at the time 
the gravel plain was being deposited, there would be nothing to hinder the 
gravel from spreading out in fan shape across the whole valley. Instead, 
the gravel is confined to a narrow belt along the east side of the pond. 
Here was a torrent swift enough to make granite bowlders 3 feet in diame- 
ter almost as round as marbles, and depositing a gravel plain 10 to 20 feet 
higher than the present pond, strewing the margins of the pond with steep 
bluffs of bowlderets and bowlders, yet scrupulously confining itself to the 
eastern border of a mountain valley. 

The only satisfactory explanation of these facts is that the glacial river 
was confined between ice walls and that the area which Bryants Pond now 
occupies was then covered with ice. ‘True, in the pass north of North 
Woodstock the glacial river may at this time have extended from one side 
of the valley to the other, like an ordinary river, yet it could not have 
followed the course it did without the presence of ice some miles to the 


222 GLACIAL GRAVELS OF MAINE. 


north in the Androscoggin Valley at Rumford, and also in the Little Andros- 
coggin Valley at Bryants Pond. Practically it was a glacial river as far 
south as the south end of Bryants Pond. 

South of this point the valley of the Little Androscoggin is bordered 
by high hills. A plain of mixed sand, gravel, cobbles, and bowlderets, with 
some bowlders, extends along the valley to West Paris. This plain is about 
one-fourth of a mile wide, and the stones are all very much rounded, like 
those of the osar-plain at Bryants Pond. It should be noted that we are 
near the source of the Little Androscoggin, which stream is here only a 
a good-sized brook. From Bryants Pond to West Paris the slope of the 
stream averages about 35 feet per mile; from West Paris to South Paris it 
is 8 or 10 feet; and it is only 4 or 5 feet from that point to the mouth of the 
river at Auburn. Now, in the White Mountains, where the slopes are 100 
or more feet per mile, the stones in the beds of the streams are much 
rounded; but I have nowhere seen them so rounded as those in the valley 
of the Little Androscoggin from Bryants Pond to West Paris. North of 
the place where the osar-plain enters the valley of the Little Androscoggin 
there is no such drift as the plain of very round stones that extends from 
the foot of Bryants Pond to West Paris. Even in the highest late glacial 
or postglacial floods the Little Androscoggin could not at this place be a 
very large stream, for we are near its head waters. From whatever stand- 
point, then, we look at the plain of very round gravel, cobbles, bowlderets, 
and bowlders that extends from Bryants Pond to West Paris, we find neither 
the size of the stream nor the steepness of slope necessary to account for 
this plain as fluviatile sediments. Besides we know that a great glacial 
river flowed into the north end of this valley. The steep hills would pre- 
vent it from getting out of the valley. It must have flowed down the valley 
doing its characteristic work. The result was this plam, which is thus 
proved to be chiefly glacial as far as West Paris. 

At West Paris the valley of the Little Androscogein abruptly broadens 
into a triangular plain 3 or more miles im breadth. One apex of the 
triangle is at West Paris, another at Trap Corner, Paris, and the third at 
Snows Falls, where the valley narrows to 300 feet. The west side of this 
triangular valley is bordered by a plain of sand, gravel, and well-rounded 
cobbles which extends in nearly a straight lme from West Paris to Snows 
Falls. It presents the external appearances of an osar-plain. East of this 


ANDROSCOGGIN LAKES-PORTLAND SYSTEM. 223 


western border plain the broad valley is covered by sand, silt, and clay. 
At Trap Corner the fine alluvium extends for a considerable distance up 
two small tributary valleys to the same height as the clay plain of the 
main valley at that place. This proves that most of the broad valley was 
at one time covered by rather still water, approaching the condition of a lake, 
and this must have happened after the melting of the ice at that place. If 
the great glacial river that deposited the osar-plain to the north had flowed 
into the broad triangular valley below West Paris after the ice had melted, 
it must have filled up the valley with a delta-plain. Instead, the plain of 
rounded gravel and cobbles is confined to a strip along the west side of the 
broad valley hardly more than one-fourth of a mile wide. It is thus proved 
that an osar-plaim was formed in a broad glacial channel along the western 
border of the triangular valley at a time when the rest of the valley was 
covered by ice. Later, when the ice over the valley melted, this broad valley 
formed, for a time, a lake, owing partly to the great breadth of the valley at 
this point as compared with its narrowness at Snows Falls, and partly per- 
haps to the osar-plain’s acting as a dam across the valley near Snows Falls. 
In the northwestern part of this lake coarse sediment would be deposited by 
the swollen river of that time, consisting in part of portions of the eroded 
osar-plain, while east and south only the finer sediments would be laid 
down. It thus becomes reasonably certain that the drift of the broad 
triangular valley that extends from West Paris to Snows Falls consists 
of an osar-plain more or less covered by alluvium of fluviatile and lake- 
delta origin. 

Not far south of Snows Falls the valley of the Little Androscoggin 
widens so that the alluvial plain has an average breadth of about half a 
mile. It is finer in composition than it is north of Snows Falls, sand and 
gravel being most abundant, but it contains numerous pebbles and some 
small cobbles. For 1 or 2 miles south of the falls the plain shows num- 
bers of low ridges and shallow kettleholes. Then it becomes more level 
on the top, and soon a two-sided ridge is formed near the river and extends 
for about 3 miles to South Paris. It is locally known as the ‘ Horseback.” 
It has the same height as the rest of the plain, and the material appeared to 
be little if any coarser than that of the plain at the sides of the valley. 
The ridge is the result of erosion of the alluvial plain on each side of the 
horseback to a depth of 10 to 40 feet. There must be a reason why this’ 


2?4. GLACIAL GRAVELS OF MAINE. 


ridge has escaped erosion, and if fresh exposures can be found they will 
probably show a mass of coarse matter at the bottom of the ridge, perhaps 
an osar with arched cross section. We have already seen that these erosion 
ridges are common in the osar-plains, as in the valley of Martins Stream 
between Livermore and North Turner, and the whalebacks in Rumford, 
Milton, Bethel, and Woodstock. In the last-named cases it is quite easy to 
determine that they are ridges of erosion carved out from the original osar- 
plains. Here we find that the Little Androscoggin is larger than the 
streams flowimg in the valleys just named. Did it deposit the alluvial plain 
below Snows Falls as valley drift? Its drainage basin above South Paris 
covers only a few townships, and even in the Valley Drift period its flow 
was small as compared with that of the Androscoggin and Kennebec rivers, 
yet it is bordered by an alluvial plain nearly as large as theirs at the same 
distance from the shore of the sea of that period. There are in the State 
great numbers of streams haying as large drainage basins as the Little 
Androscoggin above South Paris, yet having very much smaller alluvial 
plains. This gives an antecedent probability that the alluvium of this val- 
ley is largely glacial. 

The gravel along the center of the valley below Snows Falls is well 
rounded, like that of the osar-plain northward. But. in many places I 
noticed that near the margin of the alluvial plain the gravel was but little 
worn, in some cases the till shapes being hardly modified at all, and the 
drift was almost morainal. This marginal drift resembles the ordinary 
valley drift of streams having no greater fall than the Little Androscoggin 
in Paris, and is just such work as could be expected of the river after the 
ice had melted, or at the extreme margin of the broad channel of an osar- 
plain. 

We have, then, field evidence of distinctively glacial gravel to within 
4 miles of South Paris, and we know that a great glacial river flowed south- 
ward in the valley. General analogy, as well as the local facts, indicates 
that the central part of the alluvial plain of the Little Androscoggin north 
of South Paris is an osar-plain, deposited in a broad channel between ice 
walls. Later, as the ice melted, the water extended across the whole 
valley. Alluvium was then deposited mainly at the sides of the osar-plain, 
and it was subjected to much less attrition than were the stones of the oider 
elacial gravel. It would naturally happen that after the ice had all melted 


ANDROSCOGGIN LAKES-PORTLAND SYSTEM, 225 


in the Little Androscoggin Valley some would still linger in the Andros- 
coggin Valley farther to the north, and therefore a flood of glacial waters 
still continued to pour south from Rumford to Bryants Pond, and so on, 
down the Little Androscoggin Valley. These floods of muddy water, aug- 
mented. by the local drainage of the valley, would wash away and reassort 
the surface portions of the previously deposited osar-plain, and also carry 
along its burden of drift washed down from the freshly exposed hills. In 
this way it might happen that what might be a glacial river toward the 
north could be considered an ordinary river farther south, where it flowed 
unvexed by ice to the sea. A considerable portion of the alluvial drift of 
this valley is undoubtedly a valley delta of frontal glacial sediment, 
brought down by glacial streams and poured ovt into the open valley, like 
the sediments that gather in the valleys below the Alpine glaciers, or like 
the great plains of water-washed matter that extend south from the terminal 
moraines of the continental glacier. 

South of the South Paris and Norway villages the valley of the Little 
Androscoggin rapidly widens. By gradual transition the sedimentary plain 
becomes finer, being composed of a lower layer of silty clay overlain by 
sand and fine gravel. The upper sands have been extensively eroded, 
largely by boiling springs. At Oxford Village the plain is about 2 miles 
wide and the upper stratuni consists of fine sand. The Little Androscoggin 
here turns east. All the way to Auburn its valley is covered by deep clays 
with some overlying sand. It is uncertain how far up the valley tide 
water extended above Auburn. It is certain that a broad stream or body 
of water at one time covered the valley all the way from Norway to 
Auburn, and the lower (eastern) portion was certainly salt water. Into 
this body of water poured, not only the local drainage, but also for a time 
the glacial waters from the upper Androscoggin Valley which then flowed 
south from Rumford past Bryants Pond. The large amount of water that 
must at one time have occupied this valley is well shown by the broad 
extent of sedimentary plains in Oxford. Two lines of clays, overlain by 
sand, pass out from the main valley and rejoin it again several miles to the 
south and east. The more eastern of these outlying plains follows the 
valley along which the Grand Trunk Railway is built. The other plain 
passes around the west side of a hill lying northwest of Oxford Village and 


comes to the shore of Thompsons Pond about 2 miles west of the village. 
MON XXxIvy——15 


226 GLACIAL GRAVELS OF MAINE. 


At the shore of the pond it forms a bluff rising 8 or 10 feet above the 
water. At the narrowest place this plain is about one-eighth of a mile 
wide, and a large amount of water was required in order to form it. If 
the ice in the basin of the pond was all melted at the time of the deposi- 
tion of this plain, the whole pond must have stood at least 8 feet above its 
present level, and a delta ought to spread out in fan shape from the mouth 
of the inflowing stream. Now from this point to Oxford Village the pond 
is bordered by a clay plain, and a sedimentary plain nearly filled up the 
lake, which was flooded with water by the building of the dam at Oxford. 
But south of here no sand or elay borders the lake, except a little near the 
mouths of the streams—certainly no such sheet as could be expected if a 
large river flowed into the pond 2 miles from its outlet and at a time when 
it stood 8 feet or more above its present level. At this time most of the 
basin of Thompsons Pond must have been covered by ice. Thus the sedi- 
mentary plains of Oxford appear in part to have been deposited in broad 
channels bordered by ice, and give good ground for suspecting that these 
broad channels practically formed a series of glacial lakes in which a part 
of these fine sediments were deposited. Subsequently the ice melted, and 
a body of water, probably marine, filled the whole lowez valley of the 
Little Androscoggin. How far this was fluviatile, estuarine, or marine is 
somewhat uncertain, and the hypothesis is suggested that these broad sheets 
were, in part at least, bordered by ice. 

From Oxford Village a broad, low, plain-like valley (known as Rabbit 
Valley) extends southeastward to Poland Post-Office. About a mile from 
the Little Androscoggin a ridge bordered by ravines of erosion is found 
in the midst of the plain of sedimentary clay and sand which here covers 
the valley. Farther south what appears to be a continuation of this ridge 
rises higher than the plain of fine sediment, and soon crosses a pond,’ 
which nearly divides it into two separate lakes. Whatever be the char- 
acter of the erosion ridge farther north, this ridge at the pond is distinctly 
an osar. Within 2 or 3 miles the ridge is lost in a rather level plain of 
sand, gravel, cobbles, and bowlderets, which for several miles is from 
one-fourth to one-half of a mile in breadth. The unmistakable glacial 
origin of this osar-plain makes it appear possible, perhaps probable, that 
the rather horizontally stratified plain of clay and sand which borders the 
ridge toward Oxford Village was laid down in a broad channel within 


ANDROSCOGGIN LAKES-PORTLAND SYSTEM. DAG 


ice walls, so broad as to approach the character of a glacial lake. In the 
valley of Range Stream, not far north of Poland Post-Oftice, the osar-plain 
broadens somewhat, and becomes finer toward the north and east, passing 
from gravel into sand, and finally into a clay plain, which extends north- 
eastward and at Mechanic Falls joms the broad plain of clay covering 
the Little Androscoggin Valley. Here, then, is a delta-plain where the 
glacial river at one time flowed into the broad body of water which 
occupied the valley of the Little Androscoggin after the ice had melted 
to this point but still remained at Oxford. 

Approaching Poland Post-Office, the gravel becomes coarser for about 
2 miles along the north side of the Lower Range Pond. Here are great 
numbers of very round cobbles, bowlderets, and some bowlders. Then 
the gravel becomes finer toward the southeast, and in the valley of the 
Worthley Brook consists of a rather thin plain of sand, which has been 
much eroded by the stream. 

A series of hills borders on the south the valleys of the Androscoggin 
and Little Androscoggin from Brunswick to Oxford. Four low passes 
penetrate these hills. One leads from Durham south through Pownal, 
one past Danville Junction, a third lies south from Oxford along Thompson 
Pond, and the fourth is in the eastern part of Poland, leading along the 
eastern base of the high granitic hills on which the Poland Spring Hotel 
and the Shaker Village are situated. The osar-plain turns south along 
the valley of Worthley Brook and penetrates the last-named pass. It is 
here composed of rather fine drift, and is somewhat interrupted in the 
jaws of the pass. Soon after entering New Gloucester the system expands 
into plains from 1 to 3 miles wide, which extend southward nearly to 
Gray Village. The western portion of this large plaim shows a rolling 
surface and much coarse matter (cobbles, bowlderets, and bowlders). 
Toward the east and south the surface is more level (except where there 
are sand dunes) and the material is finer, passing at last into fine sand. 
In the midst of the sedimentary plain are several hills covered with till. 

It will be seen that the eastern portions of the great plain of New 
Gloucester and Gray present the characters of a delta. ‘Their relations to 
the marine clays are significant. Two bays of the sea once united at these 
plains. A line of marine clays extends up the valley of the Presumpscot 
River to Windham, and thence northeastward up the broad valley of Pleasant 


228 GLACIAL GRAVELS OF MAINE. 


tiver past Gray Village to North Gray. At the same time a bay 10 te 
20 miles wide covered the lower valley of Royal River and extended as 
far north as Danville Junction. It joined the first-named arm of the sea at 
North Gray. Thus a large part of Cumberland and Gray at that time 
formed an island, separated from the mainland by a sheet of water 1 to 5 
miles wide in northern Gray and in New Gloucester. The southeastern por- 
tion of the great delta-plain of New Gloucester and Gray passes gradually 
into clay about 14 miles north of North Gray. The western portion, which 
partly presents the external features of an osar-plain, partly those of reticu- 
lated kames, extends southward to within three-fourths of a mile of Gray 
Village. The southern portion is a plain of gravel, with cobbles and some 
bowlderets, from one-fourth to three-fourths of a mile wide. It ends ina 
steep bank and is covered at its base by the sedimentary clay. The coarse- 
ness of the matter composing this plain proves that it was not deposited in 
the open sea far beyond the ice front. 

The late glacial history of this region must be about as follows: First, 
a broad plain of coarse gravel, etc., was deposited within an ice channel or 
series of channels along the western side of the great plains. Near Dry 
Mills, in the northern part of Gray, this plain of coarse matter does not 
extend back to the hills, but ends on the west in a rather steep bank. It also 
forms the barrier which has dammed back the waters of Dry Mills Pond. 

Subsequently the ice melted, and the sea advanced so that the glacial 
river formed a marine delta east of the original osar-plain. This is the 
delta not far north of North Gray. Still later the sea advanced up the 
valley of the west branch of Royal River, and the glacial river flowed 
into the sea in this valley not far east of Sabbathday Pond in New 
Gloucester. 

South of the great plains of New Gloucester and Gray there are two 
discontinuous series. They are provisionally classified as delta branches 
of one system, though it is difficult to determine whether they were 
contemporaneous. 

The first of the western series is the level plain on which Gray Village 
is situated. It is separated from the more western plain above described 
by an interval of more than a mile of marme clay. On the north bowlderets 
and cobbles abound, but the material grows finer toward the south, and 
the sand plain ends in marine clay within about three-fourths of a mile. 


ANDROSCOGGIN LAKES-PORTLAND SYSTEM. AS) 


The transition is quite abrupt, and while the plain is a delta, it is uncertain 
whether it was deposited in the sea or in a glacial lake. The sedimentary 
clay continues for about a mile south of Gray Village, and no gravel 
appears above the clay for about that distance. Then in a low north-and- 
south valley between high hills is found a somewhat discontinuous series of 
broad hummocks and low ridges, which expands in the western part of 
Cumberland and the northwestern part of Falmouth into a broad marine 
delta. A tongue of this plain one-fourth of a mile or somewhat less in 
breadth extends southward along the eastern base of Black Strap Mountain 
for nearly 3 miles in Falmouth. The transition between this plain and 
the marine clay is so abrupt at the sides that it must have been deposited 
between lateral walls of ice. There is a gradual transition to finer sedi- 
ments toward the south, and this indicates a delta of some kind. The 
glacial stream either poured into a bay of the sea that extended back into 
the ice or into a glacial lake. In the case of this and many similar 
deposits it will require cross sections of the deltas and the marine clays to 
determine the stratigraphical relations of the coarser and finer sediments. 
Such sections are not easily made without excavations for that special 
purpose, since most of the excavations for road gravel, etc., are purposely 
made within the mass of eligible gravel and not at the place of transition 
from the sands to the clays. 

Black Strap Mountain (Mount Independence of the Coast Survey) 
formed part of an island when the sea was expanded. Along the sides of 
the ‘‘mountain” are numbers of beaches, representing a considerable marine 
erosion of the till, and these gravels have to be distinguished from glacial 
gravel. The marine clays about its base are deep and sometimes hide 
masses of the glacial gravel. This makes the region a somewhat difficult 
one to explore. I have not been able with certainty to trace this series 
south of the long narrow plain above described. 

There is a small delta at the West Cumberland Fair-eround. It is 
situated about a mile east of the delta just described, but does not appear 
to be connected with it. This delta-plain is of rounded fan shape, and on 
the margins toward the south, southeast, and southwest the transition from 
the sand to the marine clay is so gradual as to strongly indicate that it was 
deposited in the open sea by a small glacial stream that probably was not 
connected with any other stream. 


230 GLACIAL GRAVELS OF MAINE. 


We now go back to the great marine delta-plains of New Gloucestc: 
and Gray. North Gray is situated in the valley of a tributary of Royal 
River. To the south and west of this valley is a broad-topped hill, or 
gently rolling plateau, which rises about 75 feet above North Gray and 
extends for several miles southward. A gravel plain about 1 mile broad 
and 3 miles long is found on the top of this plateau. It comes to the 
eastern brow of the hill, where it ends in a rather steep slope, almost a 
bluff. Toward the north the plain consists of broad reticulated ridges, 
inclosing numerous kettleholes, one of them being a large basin 70 or 80 
feet deep. Bowlderets and bowlders are here very abundant, and most 
of them are well rounded. Toward the south the plain becomes quite 
level on the top, and changes to fine gravel, and finally to sand. Beyond 
the sand is marine clay, but I am not certain whether the transition 
between the sand and the clay is such as to prove that this is a delta 
deposited in the sea or in a glacial lake. The external appearances favor 
the hypothesis that this is a marine delta-plain. On the slopes of the hill 
just north of this plain there are many moraine-shaped ridges running 
nearly north and south. It is uncertain whether they were piled in their 
present shapes by the glacier or are erosion ridges left after the glacial 
streams had washed away portions of the till, leaving these as uneroded 
ridges. 

South of this broad delta in Gray is a level country for 3 or 4 miles, 
deeply covered by marine clay. Then the glacial gravel begins again as a 
round plain near one-half mile in diameter, situated at the north end of 
Walnut Hill, in North Yarmouth. From this point a low level plain one- 
eighth of a mile or somewhat more in breadth borders the eastern base of 
Walnut Hill, and continues with perhaps a few short gaps to Cumberland 
Center, where it ends abruptly. This plain nowhere rises more than 10 to 
25 feet above the marine clay which overlies its flanks and which some- 
times covers the gravel out of sight. A road is made on top of the gravel 
plain for several miles in the midst of a thickly settled country. Hence 
numerous wells have been dug in the gravel plain or near it. Often when 
the surface shows only the marine clay, wells penetrate the clay into the 
gravel and prove that the plain is nearly contmuous from the north end of 
Walnut Hill to Cumberland Center. In a few cases (e. g., in the western 
part of Cumberland Center) wells have passed through the gravel into sedi- 


ANDROSCOGGIN LAKES-PORTLAND SYSTEM. 231 


mentary clay. The proper interpretation of this fact is uncertain. The sea 
waves may have washed away the top of the gravel ridge and strewn the 
gravel over marine clay previously deposited on the flanks of the ridge. 
On the other hand, the glacial rivers may have laid down both the clay and 
the overlying coarse sediments in their present positions, either in a broad 
kame channel approaching the character of a glacial lake or in a bay of the 
sea inclosed between lateral walls of ice. But in the last-named case the 
plain ought to show a transition into the marine clays at the south end of 
the plain. The abruptness of the transition favors the hypothesis that the 
plain was deposited in a glacial lake, and that some of the marginal clay 
is not marine but osar border clay. Yet for a mile north of Cumberland 
Center the ridge is so situated that it would be much exposed to the waves 
of the sea. Its surface is gently rounded in cross section, and the aboye- 
described phenomtna may be due to wave action. It will require study of 
many sections in order to write out the full history of the plain near Cum- 
berland Center. 

Between Walnut Hill station on the Maine Central Railroad and Cum- 
berland Junction there are two plains of glacial gravel lying one-fourth 
mile east of the main ridge or plain. <A projecting spur of the main plain 
has been extensively excavated by the railroad company a short distance 
south of Walnut Hill station. 

South of Cumberland Center lies a rather level region coverea by 
marine clay, and no gravel appears on the surface for about a mile. About 
one-fourth of a mile west of Cumberland Junction, Maine Central Rail- 
road, the gravel begins again as a broad ridge, with gently arched cross 
section, capping the top of a low north-and-south hill. This ridge extends 
southward to within one-fourth of a mile of West Falmouth station, it bemg 
narrower and somewhat discontinuous toward the south. At various places 
bars or tongues project obliquely down the eastern slope of the hill, South 
of West Falmouth lies the plain of marine clay that borders the Presump- 
scot River. No glacial gravel appears in this plain for more than a mile. 
A short distance south of the river a small gravel plain appears on the top 
of a low hill. Two other small plains, separated by intervals, bring us to 
a much larger gravel plain, known as Stevens Plain, situated at Mornills 
Corner in the town of Deering. This plain is somewhat oblong in shape. 
It is nearly a mile in length, and about half as broad. It is now very 


232 GLACIAL GRAVELS OF MAINE. 


level on the top, but it is in a thickly settled region and the surface may 
not be in its original condition. The margin shows on nearly all sides a 
steep slope outward, and the strata dip correspondingly at the exposures 
examined. The material of the plain is fine gravel and sand with some 
thin layers of silty clay. At some of the excavations examined the sedi- 
mentary matter rested directly on the solid rock, which has lost most of the 
glacial striz: and is sand carved and polished under the action of the glacial 
streams. A broad ridge of glacial gravel begins a short distance north of 
Stevens Plain and extends north to the Presumpscot River. Wells are 
said to have been dug 80 feet in this ridge without passing through the 
gravel. Between this ridge and the delta-plain in West Cumberland and 
Falmouth, before described as lying along the northwestern base of Black 
Strap Mountain, there is an interval of fully 4 miles. If the Gray-West 
Cumberland gravel series has any extension it must be this ridge extending 
north of Stevens Plain. The local deposits of subangular gravel on the 
south slopes of Black Strap 
Mountain are seabeaches so 
far as examined. 

Stevens Plain is prob- 
ably a marine delta. The 


OE: 


mth) g eon 


Fig. 23.—Landslip at Bramhall Hill, Portland. a, a, old surface, overlain Pen x iy 
with 6 feet of well-rounded gravel and cobbles, with some bowlderets. outward or anticlinal dip ot 


the strata on all sides is probably due in part to the surf washing over 
the top of the plain. The gravel is slightly coarser on the west side of 
the plain. 

The next deposit of the system is found as a ridge or terrace formed 
against the west end of Bramhall Hill in the western part of Portland. 
The osar matter is here rather coarse, containing a large proportion of cob- 
bles, bowlderets, and some bowlders, and most of them are considerably 
rounded by water. Extensive landslides have taken place on this hillside. 
Near the Boston and Maine transfer station a section was exposed a few 
years ago that showed an old sod covered by several feet of well-rounded 
gravel and cobbles. The roots of grasses and other plants could still be 
distinguished. The same landslips have covered the fossiliferous marine 
clays with the glacial gravel. The hills of Portland would be exposed :to a 
somewhat violent surf when the sea stood at their level. The waves have 
washed away much of the glacial gravel from the hills at each end of the 


ANDROSCOGGIN LAKES-PORTLAND SYSTEM. 233: 


city, and spread it as beach gravels over the lower slopes of the hills, and 
often upon the fossiliferous marine clays. In consequence of the landslips. 
and the overlap of the beach gravels, Portland is a difficult locality for 
investigating the relations of the glacial gravels to the fossiliferous marine 
clays. 

South of Portland Harbor the connections of this system are somewhat 
obscure. In Cape Elizabeth, near the Boston and Maine Railroad, is a sand- 
and-gravel plain, not far southwest of Portland, and there is another pretty 
large plain near Oak Hill station, Scarboro. It is probable that these are: 
the connections of this system rather than the more eastern line of gravels 
toward Two Lights. Whether any of the sand beaches toward Old Orchard 
are part of this system is uncertain. 

The length of the system, from Lake Mooselookmeguntic to Searboro, 
is 100 miles. 


KENNEBAGO KAMES. 


These are reported by Mr. Huntington, of the New Hampshire Geo- 
logical Survey, as being found in the valley of the Kennebago Stream, 
about 10 miles north of Lake Mooselookmeguntic. I explored this river for 
2 miles north of the lake, and found an alluvial plain, which possibly is a 
frontal plain. The kames referred to above are in the proper position to be 
a branch of the long Portland system, but more probably are a local sys- 
tem of late date, when the ice had retreated up the valley for several miles. 
above the lake. 


LOCKES MILLS BRANCH. 


The broad alluvial intervale of Bethel extends nearly to South Bethel. 
At the eastern edge of the alluvial plain begins a series of reticulated ridges. 
inclosing kettleholes, which extends eastward past Lockes Mills in Green- 
wood. Approaching the top of the divide between Androscoggin and 
Little Androscoggin waters, the gravel series becomes finer in composition 
and expands into a small sand plain at an elevation of about 75 feet above 
the Bethel intervale. From the top of the divide eastward to Bryants 
Pond there is but little alluvium. A glacial stream from this direction 
joined the main system at Bryants Pond and left a plain of gravel extend- 
ing about one-fourth of a mile west from the main osar-plain. From that. 
point to the top of the divide not far east of Lockes Mills I have not been 


234 GLACIAL GRAVELS OF MAINE. 


able to trace the gravels. This makes it probable that not much if any 
overflow took place from Lockes Mills eastward after the ice had become 
melted west and northwest of Bryants Pond. 

A short line of glacial gravels comes from the north and joins the 
South Bethel series near Lockes Mills. There are some signs that this 
series extended northward across the middle intervale of the Androscoggin 
in Bethel as an osar-plain, and then up the valley of Bear River toward 
Umbagog Lake. I have not been able to find time for a careful explora- 
tion of the route, and provisionally mark this gravel series as extending 
only about a mile north from Lockes Mills. 

It has already been noted that there may have been an overflow from 
the direction of Umbagog Lake to Andover, and that possibly a branch of 
the Portland system followed the valley of the west branch of the Ellis 
River. : 

GENERAL NOTE ON THE PORTLAND SYSTEM. - 

Three times this system of glacial gravels goes up a valley of natural 
drainage to its source and crosses hills into other valleys, but it does not 
cross hills higher than 150 feet. In order to penetrate the high hills by so 
low passes, it makes some remarkable deflections in its course. At Oxford 
there was in front of it a very low pass southward (along Thompson Pond), 
but it took a higher pass southeastward through Poland, following a course 
more nearly parallel to the glacial strie than was the other. The system 
takes the form of an osar or osar-plain for most of the way north of the 
Gray-New Gloucester marine delta. South of that point it is constantly 
discontinuous, i. e., it consists of a series of plains or broad ridges sepa- 
rated by intervals from a half mile up to 3 or 4 miles. In this part of its 
course the gravels appear on the tops of low hills or along the eastern bases 
of such high hills as Walnut Hill and Black Strap Mountain. The plain 
at Oak Hill in Searboro, Stevens Plain in Deering, the plain at West 
Cumberland Fair-ground, and the other plain west of it in Cumberland 
and Falmouth, also a large part of the Gray-New Gloucester plains, I con- 
sider as marine deltas. The last named are by far the largest of these, and 
are situated at an elevation of 200 to 230 feet. Several others of these 
plains are deltas of some kind, but I am not certain whether they were 
deposited in the sea or in glacial lakes. Several of these deposits show 
some but not all of the characters of deltas. Their material is so coarse. 


CASCO-WINDHAM SYSTEM. 230 


even to the edge of the deposit, as to prove that they were formed between 
ice walls and not in the open sea. The student of the drift of Maine should 
certainly explore this system, though in many places it is quite inaccessible 
and considerable time is required to do it justice. 


LOCAL ESKER IN WESTBROOK. 


A short kame is situated on the north side of the Presumpscot River a 
short distance east of Cumberland Mills. 


CASCO-WINDHAM SYSTEM. 


Thompson Pond extends from Oxford south through Otisfield and 
Poland into Casco. It occupies a long north-and-south valley, which at the 
north is 2 or 3 miles wide, but becomes narrower in Casco, so that at 
the south end of the pond it is hardly one-eighth of a mile wide, while 
south of the pond lies an almost V-shaped valley, bordered by high 
granitic hills. At the foot of the pond the bases of the bordering hills are 
strewn with a number of hummocks of till, also some morainal ridges, 
which are somewhat transverse to the valley. They appear like moraines 
of a local glacier occupying the basin of the pond. This narrow valley 
terminating the much broader valley toward the north would be favorable 
for the formation of moraines during the final melting of the ice, on account 
of the great convergence of the movement into so narrow a pass. In the 
midst of the valley, at the south end of the pond, begins a series of low 
bars of glacial gravel. The stones have been but little changed from their 
till shapes, a fact which proves this to be near the north end of the system. 
Only a small brook flows northward into the lake, and there is no way of 
accounting for this gravel as fluviatile alluvium. Going south we find the 
gravel becoming rounder. A very low divide separates the waters of 
Thompson Pond, flowing north, from those flowing south. The glacial 
river flowed over this divide and thence in a nearly straight line to Rattle- 
snake Pond, Casco. Not far north of this pond it flowed over a vertical 
cliff of rock 20 feet high. The cliff faces south, and a subglacial river 
flowing in that direction would naturally have eroded the rock at the base 
of the cliff if it flowed over it so as to form a waterfall, but there is no pot- 
hole or visible channel of erosion in the solid rock. The course of the 
glacial river could easily be traced at this point by the piles of rounded 


236 GLACIAL GRAVELS OF MAINE. 


gravel, cobbles, and larger stones found at short intervals in a strip only 
about 100 feet wide. The rock, where unweathered, was very smooth, but: 
whether this was due to water polish or to the attrition of the glacier was. 
uncertain. There was little till along the line of the glacial stream. Here, 
then, was a rather small glacial stream that eroded the till and tumbled 
over a steep cliff, yet did not erode a traceable channel in the solid rock or 
form a pothole. The stones of the glacial gravel are all very much 
rounded here, and must have been subjected to a large amount of rolling. 
A plausible explanation of these facts lies in the hypothesis that the stream 
was for a time occupied in eroding the till, and that it ceased to flow soon 
after the rock had been laid bare. The gravels pass beneath the water at 
the north end of Rattlesnake Pond and soon reappear on the western 
shore. The glacial river followed this shore of the pond all the way to its. 
south end. Between Rattlesnake and Panther ponds the glacial gravel 
takes the form of an osar-plain. The gravel reappears near the south end 
of Panther Pond, and continues as an osar-plain to Raymond Village. 
Here, near where the system crosses the outlet of Panther Pond, there is. 
apparently a short gap in the gravel plain. The plain soon begins again, 
and continues its southwest course till it reaches the shore of Sebago Lake, 
when it turns south and follows the east shore of the lake for a half mile or 
more. It rises 6 to 12 feet above the lake, and often ends at the lake ina 
cliff of beach erosion. In all this part of its course the osar-plain continues 
an eighth of a mile in breadth, or in places a little broader. There was. 
nothing to hinder an ordinary stream having a southwest course from 
sweeping its sediments out into the lake. The fact that there is no fan- 
shaped delta at this pot, though the stream that deposited the osar-plain 
flowed at an elevation of several feet above the lake and was rapid enough 
to transport cobbles and bowlderets, is conclusive proof that at the time the 
plain was being deposited the basin of Sebago Lake was covered by ice at. 
this poit. 

The gravel plain soon leaves the shore of the lake and continues. 
southward over a pass 50 to 70 feet high to North Windham. In this part 
of its course the system takes the form of a plexus of broad reticulated 
ridges and hillocks, and it contains many kettleholes and hollows of all 
sizes up to lake basins. Toward the south the plains spread out in fan 
shape and the ridges become lower and gradually coalesce into a rather 


| 
| 


CASCO-WINDHAM SYSTEM. DAB) Tl 


level plain composed largely of sand and fine gravel, which near North 
Windham is not far from 2 miles broad. South of this point the gravel 
narrows so as to form a rather level plain about one-fourth of a mile wide, 
which continues southward past Windham Hill to a point about one-half 
mile south of Windham Center. Near the south end of this plain the 
material is very coarse, consisting chiefly of cobbles with bowlderets and 
bowlders. 

In many places in this system there are great numbers of rounded 
bowlders 2 to 4 feet in diameter, a fact which favors the hypothesis that 
it was deposited by subglacial streams. 

South of Windham there are several plain-like deposits of glacial 
gravel in Gorham and Scarboro which are probably marine deltas. The 
largest of these plains is at Gorham Village. They are in the proper posi- 
tions to have been formed by the same glacial river that brought down 
the gravels of the Casco-Windham system. But the country is so level 
that we have no hills to act as barriers to confine the glacial rivers, and the 
intervals between the plains are so long that provisionally I mark the 
system as ending in Windham. 

The gravels of this system form, wholly or in part, the dam which 
caused the formation of Little Sebago Lake, in Windham and Gray. The 
original outlet of this lake flowed west into the Presumpscot River, and its 
bed shows only glacial gravel for some distance from Little Sebago Lake. 
An artificial channel has been dug for the purpose of taking the water of 
the lake south into the Pleasant River, the small stream flowing from 
Gray southwestward into the Presumpscot in Windham. This channel is 
dug wholly in the glacial gravel. 

The North Windham Plains pass by degrees into sand, and finally 
into marine clay toward the south and east. They are marine delta- 
plains in part, found in the arm of the sea which extended from Windham 
northward past Gray and joined the bay that then covered the valley of 
Royal River. But perhaps there is a continuous plain of purely glacial 
gravel near the axis of the area which is continuous with the Windham 
Center Plain. 

At Raymond Village the osar-plain is bordered and partly covered by 
sedimentary clay. This is at an elevation of about 20 feet above Sebago 
Lake. There is no continuous sheet of clays at this elevation around the 


238 GLACIAL GRAVELS OF MAINE. 


lake, and this disproves the theory that the lake or the sea stood at this ele- 
vation. This clay is probably osar border clay deposited in a very broad 
channel within the ice at a very late period of the Ice age. 

This system lies in a region where the rocks are chiefly granitic and 
the till is very abundant. Although not long, it contains a very large 
amount of gravel. 


GRAY-NORTH WINDHAM SERIES. 


On the eastern side of Little Sebago Lake is a high range of hills 
which extends continuously northward to Poland. At a point about west 
of Gray Village a discontinuous series of short ridges of glacial gravel 
begins near the eastern base of this high range. At the north end the 
gravel is but little waterworn, and it is separated from the Gray-New 
Gloucester plains by a hill more than 100 feet high. For these reasons I 
regard this series as distinct from the Portland system, although the two 
series are only 2 or 3 miles apart in Gray. This series extends southwest- 
ward, passing ‘about one-fourth of a mile west of West Gray. It soon 
becomes a continuous osar-plain, and when approaching North Windham 
rapidly broadens into a delta-plain. Near North Windham it is difficult to 
distinguish the gravels of this series from those brought down by the large 
glacial river from Casco and Raymond. Whether this series should be con- 
sidered a branch of the Casco system is uncertain. If the stream which 
deposited it began to flow in early glacial time, it would naturally flow into 
the larger glacial river, but if, as is more probable, it dates from the very 
last part of the Ice age, then it may have flowed into the sea at North 
Windham near where the other glacial river also poured into the sea, yet 
have been distinct from it. 


GENERAL NOTE ON THE GLACIAL GRAVELS OF SOUTHWESTERN MAINE. 


The systems of glacial gravels thus far described are not so closely 


connected with one another in any part of their courses but that it is rela-_ 


tively easy to distinguish them. Most of the gravels remaining to be 
described are connected with one another not only at the great marine 
delta-plains which were deposited at elevations from 175 to 230 feet above 
the sea, but also by transverse branches connecting the broad plains of 
reticulated ridges found above 230 feet. Some of them are also connected 
by lateral branches at points north of the plains of reticulated kames in 


Ce 


BASIN OF SEBAGO LAKE. 239 


the region of the osar-plains. As employed in this report, the word ‘“sys- 
tem” denotes the gravels deposited by a single glacial river with its 
branches, both delta and tributary. According to this nomenclature, 
almost all of the vast gravel deposits of southwestern Maine are connected 
as a single system. The word “series” will therefore be used to designate 
a single line or branch of this wonderfully complex network. An inspec- 
tion of the map will give a far better idea of these reticulations than a 
verbal description could give. In some cases it is easy to determine which 
way the water flowed that formed the transverse lines of gravel connecting 
the north-and-south series, but often this is difficult or impossible. Some- 
times the flow has probably been alternately in opposite directions. 


NOTE ON THE BASIN OF SEBAGO LAKE. 


Sebago Lake is said to have a larger water surface than any other of 
the Maine lakes. It is interesting in many ways. It occupies a broad 
north-and-south valley, which is a rock basin if the depth of the lake is 
correctly reported at 400 feet, or even if it has half that depth. One who 
stands on the high hills of Waterford and looks south along the deep, almost 
V-shaped valley which reaches southward through Harrison and then broad- 
ens into the beautiful valleys containing Long Pond and Sebago Lake, will 
see that here are some interesting questions in structural geology. From 
the standpoint of the glacialist the region is no less interesting. Several 
valleys converge toward the basin of Sebago Lake, down which the ice 
could continue to flow long after the general movement across and over the 
higher hills had ceased. From the north the ice could easily flow down 
the valley of Long Pond, also down that of the Crooked River. From the 
northeast the ice could easily flow from Raymond, Casco, and Thompson 
Pond along the valleys where lies the Casco-Windham system of glacial 
gravels, while a broad valley from near South Bridgton would allow a flow 
from the northwest. The valleys would in fact contain their local glaciers, 
and these would coalesce in the basin of the lake to form a single mer de 
g, would retreat less rapidly than the 


5) 
ice in adjoining regions so situated that the flow of the ice from the north 


glace, which, during the final meltin 


was more thoroughly cut off by high transverse hills. There are in Maine 
several places where the ice probably met the sea, and terminal moraines 
were formed at the ice front. These are: (1) At Readfield Village; (2) on 


‘240 GLACIAL GRAVELS OF MAINE. 


the southeast shore of Swan Island, in the Kennebec River; (3) in the vil- 
lage of Sabatisville; (4) near the head of Little Kennebec Bay, a few miles 
south of Machias Village; (5) at Winslows Mills, in Waldoboro. It might 
be expected that the tongue of ice that filled the basin of Sebago Lake 
would in like manner confront the sea, and, in consequence of the abundant 
flow of ice from the north, would retreat with relative slowness, a condition 
favorable to the formation of a terminal moraine. i 


NAPLES-STANDISH SERIES. 


A terrace-like ridge or level plain of sand skirts the western shore of 
Long Pond for three-fourths of a mile north of Naples Village. At this 
point it rises somewhat more than 20 feet above the pond, and there is no 
similar deposit on the east side of the pond, nor around the pond. The 
terrace at Naples Village is at least 10 feet deep. Is it an old beach, formed 
at a time when the pond stood 20 or more feet above its present level? 

1. If a terrace 10 feet deep could form as a beach on the west side of 
the pond and in a sheltered situation, then similar beaches ought to be 
found in all the sheltered bays of the lake, especially on the east side. 
‘There are no such beaches deep enough to be traceable. 

2. The erosion cliffs along the shores of the pond at its present level 
are too small to account for a terrace of sand near one-eighth of a mile 
wide and 10 feet deep. If the Naples terrace is a beach, then a corre- 
sponding erosion cliff or other sign of the erosion ought to be found around 
the lake. There is proof that the lake must have formerly stood at a higher 
level than at present, but it has left no cliffs, nor any places denuded of till, 
nor any recognizable beaches. 

3. No stream, except mere brooks about a mile long can ever have 
flowed into Long Pond at Naples Village. The sand terrace can not, there- 
fore, be a delta brought by streams into the lake at a time when it stood at 
a higher level than at present. 

It thus appears that the sand terrace at Naples is neither a beach nora 
lake delta, and the only way to account for it is to assume that it is an osar- 
plain. The plain continues southward along the west shore of Brandy 
Pond (Bay of Naples), becoming coarser toward the south; and at the out- 
let of this pond it has become a two-sided ridge with arched stratification. 
At this point there are several outlyimg ridges, somewhat reticulated, one 


NAPLES-STANDISH SERIES. 24] 


of which once formed a dam across the Long Pond (here very narrow) and 
raised it probably 20 or more feet above its present level. The outlet of 
the pond has in process of time eroded the obstructing ridge and lowered 
the level of Long and Brandy ponds. All of these ridges at the outlet of 
Brandy Pond (Songo Lock) are composed of coarse gravel with cobbles 
and bowlderets. The distinctively glacial origin of these coarse sediments 
is an additional proof of the glacial origin of the sand terrace at Naples 
Village, which is connected by a continuous deposit of sand and gravel 
with these osars. The osar-plain at Naples is remarkable from the fact that 
it is composed of such fe material at its north end. Whether the system 
extends northward under Long Pond is uncertain. There are small deposits 
of sand and rolled gravel reported on the shore of the pond and on islands 
in that direction, but I now regard them as probably being beach gravels 
of the lake. 

At Songo Lock, at the south end of Brandy Pond, there are a few 
ridges that have a northeast-and-southwest direction. They are arranged 
transversely across the valley, as the moraines of a local glacier would be, 
but on the surface they are composed of rounded gravel, and I consider 
them probably kames, perhaps deposited by a short tributary. 

South of Songo Lock an osar extends nearly continuously to the north- 
ern shore of Sebago Lake at a point a short distance west of the mouth of 
Songo River, which forms the mouth of Crooked River. The ridge ends 
in a cliff of beach erosion about 35 feet high. Part of the way south of 
Songo Lock the ridge is flanked by outlying hummocks and by a rather 
level plain resembling an osar-plain in external form. 

The evidence is thus conclusive that a large glacial river flowed south 
into the basin of Sebago Lake. Numerous credible witnesses report the 
northwest bay of the lake as being from 250 to 400 feet deep. Glacial gravel 
reappears at Sandy Beach, on the western shore of the lake, about 3 miles 
from where it disappears at the north end of the lake. A narrow plain of 
glacial gravel extends southward for several miles along the western shore of 
the lake, soon expanding into extensive plains in Standish. These plains are 
rather level, yet show some basins and reticulations. The glacial river must 
have flowed across the deep basin of the northwestern angle of the lake. 
A tongue of these plains extends southeastward to the south end of the lake, 


where it expands into a rounded plain more than a mile in diameter. Next 
MON XXxIv——16 


242, GLACIAL GRAVELS OF MAINE. 


to the lake the material of this plain is very coarse, containing great numbers 
of cobbles, with bowlderets and some bowlders. The surface is here very 
irregular, and the gravel consists of a series of reticulated ridges inclosing 
kettleholes and basins of various sizes, some of them occupied by lakelets 
and peat swamps. The Maine Central Railroad was originally constructed 
across one of the peat swamps. The peat soon sank under the weight of 
the roadbed, showing that the peat overlay a lakelet. The chasm was then 
filled up by an embankment of gravel, 85 feet above the top of the water, 
which stood at the same level as the lake. A depression 95 feet deep is 
found on the bottom of the lake a few rods north of the shore at the 
south end of the lake. It is surrounded on all sides by much shallower 
water, and is probably a kettlehole. The water at the south end of the 
lake is from 20 to 40 feet deep except at this depression. No rock in 
place appears anywhere near the south end of the lake nor along a line 
extending southeast from this point. 

The most probable interpretation of these facts is this: In preglacial 
time the region where Sebago Lake now is was drained by a valley which 
extended from the foot of the lake southeastward to the Presumpscot 
Valley near Saccarappa. In late glacial and early postglacial time this 
valley was filled by till, glacial gravel, and sedimentary clay to a depth of 
100 feet or more. After the final melting of the ice the water found the 
old drainage valley effectually dammed, and it filled up the basin till it 
began to overflow 7 miles northeast of the old channel The Presumpscot 
River (the outlet of Sebago Lake) flows over a rock bed, showing a constant 
succession of rapids and waterfalls all the way from Sebago Lake to near 
Saccarappa. This indicates that it is a recent channel for the main stream, 
though in preglacial time this valley was occupied by a branch of the main 
stream. Sebago Lake would be about 100 feet lower than it is but for the 
plain of glacial gravel at its south end, and would be greatly reduced in 
size. Portland owes the convenience of its water supply to this same dam 
of glacial gravel.’ 

The plains of glacial gravel that border the lake vary from 10 to 40 
feet in depth, except at the south end, where they exceed 130 feet. The 


1Since the above was written I have discovered that the gravelly nature of the southern 
boundary of Sebago Lake attracted the attention of Prof. C. H. Hitchcock; see Preliminary Report 
upon the Natural History and Geology of the State of Maine, p. 288, 1861. 


‘ 
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NAPLES-STANDISH SERIES. 243 


basin of the lake is somewhat triangular, and the ice would naturally con- 
verge toward the narrow end at the south. The unusually deep mass of 
glacial gravel south of the lake is probably in part a sort of terminal 
moraine formed at the end of the tongue of ice which occupied the basin 
of the lake. A small movement over the broad part of the basin and its 
tributary valleys would cause a much larger flow at the extremity, where it 
was only a mile wide. This would naturally cause a convergence of the 
flow of the ice, and also of the glacial rivers to this place, and during the 
retreat of the ice the deposition of a deep sheet of morainal matter. But 
there is no unmodified till in sight near the south end of the lake, and 
apparently the till last deposited has been entirely acted on by the glacial 
waters so as now to be a part of the plexus of reticulated ridges of coarse 
gravel, bowlderets, and bowlders that fill the valley. This makes the 
deposit approach in character the overwash or frontal plains of gravel which 
extend southward from the terminal moraines of the continental glacier. 
Ice movements probably converged more than the average depth of 
morainal matter here, where it was acted on by the subglacial rivers. 

Within a half mile from the south end of the lake the gravel of the 
plains just described becomes finer, and within 2 miles it gradually passes 
into sand, and finally into clay not far from the contour of 230 feet. A 
line of sedimentary clays extends from the sea nearly to the lake, and 30 
or more feet above the contour of 230 feet. At the north it borders the 
southern part of the gravel and sand plain, both terminally and laterally. 
The conditions of its deposition are uncertain. The gravel plain appears 
to be a marine delta at its southern extremity. 

From the foot of Sebago Lake a discontinuous series of broad, table- 
like ridges extends southward through the western part of Gorham, and 
thence by arather meandering course to near Buxton Post-Office, where it 
seems to end in a delta (probably marine), a mile or more in length. The 
intervals between the successive deposits are usually less than one-fourth 
of a mile, but toward the north they are somewhat larger. The gravel 
plains are from an eighth to a half mile in diameter, and often form some- 
what rounded caps on the tops of hills, especially those not far south of 
Sebago Lake. This series lies in a region wholly covered by the marine 
clay, unless the clay near Sebago Lake be an exception. Perhaps the 
whole series ought to be named the Naples-Buxton series. The gravels in 


Q44 GLACIAL GRAVELS OF MAINE. 


the eastern part of Gorham and in Scarboro may have been deposited 
by tlie glacial streams that formed the plain at the foot of Sebago Lake, 
but more probably, if those gravels have any connections, they will be 
found in the direction of Windham. 


SEBAGO SERIES. 


A well-defined but somewhat discontinuous series of glacial gravels 
extends for several miles along the valley of Northwest River in Sebago, 
and joins the Naples-Standish series at East Sebago. In the northwestern 
part of their course these gravels take the form of short ridges, but for 
several miles above East Sebago they take the form of a broad osar of 
fine gravel and sand, now much eroded. This series is probably due to an 
overflow from the direction of Great Hancock Pond, as will be described 
in connection with the following series. Further description of the plains 
extending from East Sebago into Standish and Baldwin will also be 


given later. 
BRIDGTON-BALDWIN SERIES. 


This important series appears to begin in Sweden as a small ridge of 
subangular gravel and cobbles situated in the valley of a small stream 
which flows southward into Highland Lake. The ridge is on the side of a 
steep hill 20 or more feet above the stream, and there is no corresponding 
ridge or terrace on the opposite side of the valley. It must therefore be 
glacial gravel. Several Islands in Highland Lake (Crotched Pond) show 
water-washed gravel, probably glacial. A short distance from the south 
end of the lake one of these islands is covered with gravel which is quite 
certainly glacial, while a large and broad osar ridge comes out of the 
water at the south end of the lake, forming in part the barrier which 
dammed back the waters of the lake. It thus appears probable that a 
single glacial river flowed from Sweden southward across the basin of 
this lake. 

A series of low ridges and hummocks extends from the lake ‘south- 
ward through Bridgton Village, and then for about 10 miles the series fol- 
lows the very low valley along which is constructed the Bridgton and 
Saco River Railroad. Excavations in Bridgton Village show pretty well- 
rounded, glacial gravel overlying till, and a gradual transition between 
them. In several places this series takes the form of an osar-ridge of coarse 


PL. XVIII 


MONOGRAPH XXXIV 


U. S. GEOLOGICAL SURVEY 


BROAD OSAR PASSING OVER HILL 210 FEET HIGH; BALDWIN. 


Glacial river flowed past the house, then turmed to the left and flowed over hill beyond, a little to left of house. 


Osar gravel is here about 


The view ts characteristic of the hill country of western Maine. 


one-eighth mile wide. 


 hummocks in foreground 


Osar plain or terrace eroded into rollin 


BRIDGTON-BALDWIN SERIES. 245 


matter, bordered on each side by a level plain of sand up to about one- 
fourth mile in breadth. It is an instructive instance of the broad osar. At 
Sandy Creek Village even the central parts of the plain are sandy. The 
valley followed by the railroad is a remarkably level pass through the high 
hills of southern Bridgton and the eastern part of Denmark. Near the 
east line of Hiram and at the north end of Barker Pond the gravels turn 
abruptly south, while the railroad continues its southwest course to Hiram 
station. The glacial river here took its course southward along the sides 
of Barker and Southeast ponds, and then it flowed up and over a hill 100 
or more feet high. On the north slope of this hill are several horizontal 
terraces of sand at various heights above Southeast Pond I found no 
recently blown sand in the region, and these terraces have the shapes of 
beaches rather than the rounded outlines of sand dunes. A considerable 
erosion has been effected by small brooks which here and there have cut 
through the terraces at right angles. I do not see how the terraces can be 
due to unequal erosion by streams of a once continuous plain of sand. The 
place deserves careful study. The brief examination I was able to give it 
suggested that the terraces were beaches formed at the edge of a body of 
water the surface of which was gradually falling. I saw no sign of an 
erosion of the till. More probably a broad, continuous osar-plain of sand 
was deposited on the hillside, and this could easily be eroded by even small 
waves, so as to form cliffs of erosion and corresponding beach terraces 
transverse to the slope of the osar-plain. At several excavations in the 
terraces bowlders from 2 to 6 feet in diameter were seen in the midst of the 
sand. They were till bowlders, not the rounded ones of the glacial gravels. 
Wind might have covered the bowlders with sand, but can not account for 
their having been dropped upon previously deposited sand. At the exposures 
examined the bowlders were surrounded on all sides by well-assorted sand, 
and there was nothing resembling till upon or within the sand—only a few 
isolated bowlders, whereas the till contains more small stones than large. 
If they were dropped from the roof of a subglacial tunnel, the tunnel must 
have been fully one-fourth of a mile wide, and we must account for the 
presence of only a few bowlders instead of a sheet of till. The theoretical 
questions arising in connection with this locality will be discussed more 
fully later. 

Having crossed the hill south of Southeast Pond, the glacial river next 


246 GLACIAL GRAVELS OF MAINE. 


crossed the valley of Breakneck Brook, a small stream which flows south- 
west to West Baldwin. It occupies a valley bordered by high hills through 
which there is but one pass southward. The glacial river flowed through 
this pass to East Baldwin over a hill 210 feet by aneroid above the point 
where it crossed Breakneck Brook, and probably from 250 to 300 feet 
above Southeast Pond. Up and over such high hills this large glacial river 
flowed, and it has left us some interesting questions to solve. The gla- 
cial sediments form a broad osar one-fourth of a mile wide, though some- 
what narrower in the pass toward East Baldwin. Near the tops of the 
hills the sediment is scanty. In the valley of Breakneck Brook and toward 
the base of the south slopes the material is very coarse, while on the north 
slopes it is sand or fine gravel. The sheet of sand and fine gravel on the 
north slope of the hill crossed by the system just south of Breakneck Brook 
has been much eroded by rains, springs, and a small brook, but no forms 
at all like the horizontal terraces that overlook Southeast Pond have been 
produced. On this slope there are numerous till-shaped bowlders 2 to 6 
feet in diameter lying upon and within the sand and fine gravel. One exca- 
vation at the roadside shows several unpolished bowlders lying upon 8 feet 
of sand and fine gravel, and the excavation does not reach the bottom of 
the sand. Evidently we have here substantially the same problem as that 
concerning the bowlders 2 or 3 miles north, in the sand terraces on the hill 
south of Southeast Pond, except that the sediment is here somewhat coarser. 
Approaching East Baldwin this series expands into plains of sand, gravel, 
and cobbles which are confluent with the other great plains of Baldwin, 
Standish, Limington, and Hollis. 


TRIBUTARY BRANCHES. 


Three short series of ridges join the main series in the eastern part 
of Denmark. They were deposited by small streams that carried off the 
glacial waters of the broad basin in Denmark and Sweden in which Moose 


Pond is situated. 
DELTA BRANCHES. 


A delta branch probably left this series near the south end of Great 
Hancock Pond. At this point a broad deposit of sand and gravel diverged 
from the main osar-plain and extends for about one-fourth of a mile up a 
hill toward the south and east. Directly in front is a low pass lying east 


ee 


a ee 


ee. er 


— 


U. S. GEOLOGICAL SURVEY 


PL. XIX 


MONOGRAPH XXXIV 


TILL BOWLDERS IN OSAR; BALDWIN. 


On north slope of hill over which osar passes from Beeakneck Brook toward East Baldwin. 


BRIDGTON-BALDWIN SERIBS. , 247 


of Beech Hill, Sebago. The gravel soon becomes discontinuous, and at 
the top of the col I could not discover any gravel. The gravels before 
described as the Sebago series begin a short distance south of this point. 
These facts make it probable that a glacial stream overflowed from Great 
Hancock Pond over the divide and down the valley of Northwest River to 
East Sebago. 

Another delta branch diverged from the main series at the point where 
it crosses Breakneck Brook and followed the valley of that stream south- 
westward. Originally a plain of coarse gravel, cobbles, and bowlderets 
extended across the narrow valley to a height of 20 to 40 feet above the 
present level of the brook. This plain has been much eroded along the 
central part of the valley, so that now small lateral terraces along the sides 
of the valley are all that remain of the original plain. By aneroid this 
brook falls 200 feet in flowing from where it leaves the main osar-plain to 
West Baldwin, a distance of about 3 miles. With such a rapid fall it is 
not surprising that only coarse sediment was dropped in the valley. At 
West Baldwin this series becomes confluent with the great plains of the 
Saco Valley. 

The history of the osar-plain in Breakneck Valley appears to be about 
as follows: At first the Bridgton glacial river flowed across the valley, then 
up and over the hill 210 feet high to Kast Baldwin. This becomes evident 
when we consider that if the channel had first been opened southwest on a 
down slope of 60 feet per mile it is extremely improbable that the water 
could subsequently have been diverted over a hill 210 feet high. The 
stream to East Baldwin has deposited much more sediment at its terminal 
plains than the other stream to West Baldwin, and if the former stream was 
not the earlier, no reason can be assigned why the larger flow should take 
place along its course. After the channel was opened southwest down the 
Breakneck Valley the water would all flow that way, unless in time of 
extraordinary flood. 

Few if any students of the drift can see the great contrast in compo- 
sition between the broad osar of the Bridgton-Baldwin series and the 
adjacent till, or see it rejecting valleys of natural drainage in order to go 
up and over hills more than 200 feet higher than the ground to the north, 
without admitting the utter impossibility of accounting for such plains of 
sand and gravel in such situations by any freak of eolian, fluviatile, 


248 GLACIAL GRAVELS OF MAINE. 


lacustrine, or marine action. No way remains for accounting for these 
plains except dy the action of glacial streams confined between ice walls. 


ALBANY-SACO RIVER SERIES. 


Measured by the amount of assorted matter which it contains, this 
is one of the greatest gravel series or systems in the State. 

The northern connections are obscure, and involve one of the most 
difficult questions relating to the drift of Maine, i.e., the determination 
of the true history of the sedimentary drift of the Androscoggin Valley 
from Bethel westward to the White Mountains. The pebbles, cobbles, and 
bowlderets of the central parts of this sedimentary drift of the Andros- 
coggin are as well rounded as those in the kame plains, and usually more 
so than those in the beds of the White Mountain streams having a fall 
of 100 feet or more per mile. In places the alluvium of the main valley 
rises considerably above that of the lateral valleys. In a word, most of 
this drift presents all the external characters of the broad osar or plain. 
Also in some places reticulated ridges are common, and there are many 
kettleholes and some lakelets in the plain, thereby presenting the features 
of the plains of reticulated kames. At Bethel the character of the alluvium 
of the valley rapidly changes. Instead of the terraced plains of coarse 
matter, which are found from Gorham, New Hampshire, to Bethel, the 
drift of the valley from the last-named place eastward becomes fixer, and 
consists almost wholly of clay and sand, except where the osar-plains 
crossed the valley, as at Rumford Poimt and in part of the valley from 
the Swift River to Canton. My explorations of this portion of the Andros- 
coggin Valley were made before I had fully distinguished the osar-plain, 
and I was then chiefly occupied in studying the work done by the local 
glacier which, for a time after the general ice movement. ceased, filled the 
valley as far east as West Bethel. I do not therefore assert positively 
that the plain of coarse alluvium that extends from the White Mountains 
east to a point about a half mile west of Bethel Village is chiefly glacial 
gravel, but all my later studies point to that conclusion. The relation of 
the earlier osar or osar-plain, if it existed, to the local glacier, will form 
an interesting subject for study, as will also the distinguishing of an osar- 
_plain proper from frontal gravels deposited while the ice was retreating 
up the valley. The probable course of this glacial stream was down the 


ALBANY-SACO RIVER SERIES. 249 


valley of the Androscoggin to near Bethel Village, where it turned south 
along the low valley in which was once surveyed a route for a canal from 
Bethel down the valley of Crooked River to Sebago Lake and thence to 
Portland. This valley lies a short distance west of Bethel Village, on the 
west side of the hill lying south of Bethel called Paradise Hill. There is 
considerable reason to suspect that there is an osar-plain of fine matter in 
the bottom of this valley, disguised by some valley drift. At one time 
there was an overflow of the Androscoggin south through this low pass, 
also down another valley which leads south from the broad Bethel intervale 
past the east base of Paradise Hill and joms the other valley just south 
of this hill. The intervale was then a lake 3 or more miles wide. The 
alluvial plains that fill these two valleys which lead south from near Bethel 
may possibly be wholly fluviatile drift, formed during this overflow of the 
Androscoggin southward, yet I provisionally mark a glacial stream as 
flowing down the Androscoggin to Bethel and thence’ southward. There 
may have been glacial overflows from the Sunday River and Bear River 
valleys. In Albany, near the top of the low pass that leads south from 
Bethel, gravel unmistakably glacial is found, and continues in the form of 
bars, ridges, and terraces down the valley of Crooked River to North Water- 
ford. The gravels have been considerably eroded by the stream, and it is 
uncertain whether the original form of these deposits in northern Albany 
was that of a broad osar-plain extending across the valley or whether there 
were two or more distinct ridges. In the southern part of Albany and the 
northern part of Waterford there is a well-defined two-sided ridge of gravel 
and cobbles in the midst of the valley, and in a few places there are two 
such ridges, bordered by plains or terraces of rather fine sand and gravel 
having nearly horizontal stratification. These extend across the valley, 
which is near a half mile in width, at two places, but in most of its course 
is but little more than half that breadth. i 

The alluvial drift of the Crooked River Valley is of composite origin. 

1. We have a broad deposit of glacial gravel taking the form of a 
broad osar, with some distant osar ridges in the midst of it. 

2. There must have been considerable stream wash from the rather 
steep hills which border the valley, especially as there are few lakes and 
ponds in the region and the floods are rather violent. The drainage basin 
is rather small, however. 


250 GLACIAL GRAVELS OF MAINE. 


3. There were two overflows, each more than one-eighth of a mile 
wide, from the Androscoggin Valley in Bethel southward through Albany 
and down the Crooked River Valley. These took place after the ice had 
melted over the broad Bethel intervale, and apparently over the Crooked 
River Valley also. Their waters probably deposited most of their sedi- 
ments before flowing over the col in Albany. As these Androscoggin 
waters. rushed down the valley they would more or less wash away and 
reclassify the glacial gravel previously deposited. 

It thus becomes specially difficult to determine whether the plain of 
finer sediments that borders the ridges which rise a few feet above the rest 
of the plain is osar-plain or valley drift or both. The ridges were without 
doubt deposited in narrow channels within ice walls. From general analogy 
it is probable that the original channel broadened and that an osar-plain 
was laid down in the broad channel, and that this was subsequently acted 
uvon by river floods and covered by some valley drift. 

At North Waterford the Crooked River turns abruptly eastward, and 
for several miles it is bordered by erosion terraces of gravel and well- 
rounded cobbles. Apparently a continuous plain one-eighth to more than 
one-fourth mile wide once extended across the whole valley. In the eastern 
part of Waterford the river again turns a right angle and flows southward. 
The valley here widens for 2 or 3 miles, but the gravel plam does not 
broaden correspondingly. It takes the form of a plain three-fourths of a 
mile wide and about twice as long, situated on the west side of the river. 
At the north it consists chiefly of coarse gravel, cobbles, and bowlderets, 
all very much rounded. Although rather level on the top, the plain incloses 
Papoose Pond and several kettleholes. Toward the south it becomes some- 
what finer in composition, yet it ends in gravel which contains some cob- 
bles and large pebbles. It can not, therefore, be a delta deposited in a 
large body of still water. Along the eastern side of this gravel plain and 
for several miles below this point the valley of Crooked River is covered 
by a plain of sand one-eighth to one-third of a mile wide. This is often 
very fine and silty, and sometimes contains a little angular gravel near the 
stream, the result of the erosion of the till. The contrast in shape between 
this gravel and that contained in the present bed of the stream as compared 
with the very round stones of the gravel plain that extends from North 


3 
i 
f 
7 
3 


ALBANY-SACO RIVER SERIES. 251 


Waterford to Papoose Pond is very great, and shows that the gravels of 
the osar-plain have been subjected to much more atirition. Going south- 
ward in the valley, the lower layer of the valley drift becomes clayey. It 
is overlain by sand containing some angular gravel—mere tillstones which 
are scarcely polished. The plain of valley drift rises 20 to 30 feet above 
the present bed of the river, which is bordered by two and sometimes three 
terraces of erosion. At Edes Falls, in Otisfield, the underclay is overlain 
by several feet of subangular gravel, sufficiently worn to suggest glacial 
origin. Perhaps there are local kames somewhere in the midst of the val- 
ley and part of the gravel was washed away by river floods and spread 
over the previously deposited underclay. No kames appeared near this 
place in the banks of the river, but they may be situated near by and are 
now hid by the valley drift. South of Edes Falls the plain of valley drift 
is in general from a half mile to more than a mile in breadth. The lower 
stratum is clay, while the upper is a thick layer of sand, which in many 
places has blown into low dunes. For several miles north of Sebago Lake 
the upper and lower layers of the valley alluvium have about the same 
composition, and both are a fine silty sand. As stated elsewhere, the river 
here has eroded a channel bordered by steep cliffs of silt, and there are no 
higher erosion terraces, i. e., the rates of erosion and deposition are here 
substantially equal. The upper end of the original basin of Sebago Lake 
has been silted up for 2 or 3 miles, and perhaps farther. The Crooked 
River unites with the outlet of Long Pond to form the Songo, which mean- 
ders back and forth in a remarkable manner. This stream has been 
celebrated by Longfellow in his song of ‘“‘The Songo River.” 

We thus see that true osar-ridges extend from Albany down the 
Crooked River Valley to North Waterford. Then for several miles the 
valley contains a plain of gravel, with cobbles and bowlderets too large 
and too round to bea part of the valley drift, and ending in a broader 
plain showing some of the characteristics of a delta, but not such a delta 
as should form at the end of such a large glacial river as flowed through 
Albany to North Waterford. Then for many miles, to Sebago Lake, there 
is nothing in the valley that resembles the drift of the upper valley or that 
can be considered as glacial gravel proper, unless it be a short deposit near 
Edes Falls. That a large glacial river should end in that small plain at 


Daye GLACIAL GRAVELS OF MAINE. 


Papoose Pond near East Waterford seemed so unusual that it demanded 
further investigation, although as yet I did not have even a hint of the 
true condition of things at North Waterford. 

As stated already, the Crooked River turns abruptly east at North 
Waterford. From where the river turns east another valley leads south- 
west, so low that a dam of 50 or 75 feet would probably turn the Crooked 
River southwest into the Saco River. Kezar Brook originates in the Five 
Kezar Ponds, only about 2 miles from North Waterford, and flows south- 
westward in this valley. 


DELTA BRANCH AT NORTH WATERFORD. 


I have long since learned that glacial rivers bear careful watching. 
Their deceitfulness is well exhibited at North Waterford. At the time of 
my first visit to this region, in 1878, diverging or delta branchings of osar 
systems were unknown to me. I then went for about a mile down the river 
below North Waterford and found the gravel extending down the river. I 
inferred there was a Crooked River series, of which the gravel at Ede’s 
Falls, which had been described to me, was a part. Several years later I 


explored the whole valley and discovered that the glacial gravel ends near 


East Waterford in the plain at Papoose Pond. A full investigation then 
followed. Two branches of the glacial river that came down from Albany 
diverged at North Waterford. The smaller one followed the Crooked River 
Valley a few miles to Papoose Pond. The larger one crossed a low col and 
followed the valley of Kezar Brook southwestward. For several miles 
eravel takes the form of a series of ridges and terraces of coarse osar 
material. Some of these ridges are more than 50 feet high and are very 
broad and massive. Approaching Lovell Village, the series takes the form 
of sand plains, having a gently rolling surface, as if the sand had been 
deposited in a broad channel upon gravel ridges which had previously been 
formed in narrower channels. The sand plain is here near a mile wide. 
The series here leaves the valley of Kezar Brook and turns abruptly south- 
ward over a rolling plain. It passes through Sweden, Fryeburg, and Den- 
mark, and enters the Saco Valley about 2 miles east of East Brownfield. 
In all this part of its course it is a kind of osar-plain, not so level on the 
top as most osar-plains, and containing, at least on the top, much sand or 


NORTH WATERFORD BRANCH. 253 


very fine gravel. It skirts the western base of Pleasan, Mountain and the 
eastern side of Kezar Pond and two other small ponds in Fryeburg. The 
origin of these ponds is discussed elsewhere. 

For 25 miles this great series is seldom less than one-fourth of a mile 
wide, and it often has three or four times that breadth. No central domi- 
nant ridge could be distinguished at the places examined. If such there 
was, it has been covered by the sediments which were brought down by the 
rush of the vast river which in later times swept down this broad thorough- 
fare of waters. ‘The great volume of the sediments is strongly in favor of 
the hypothesis that there was an overflow from the Androscoggin Valley 
southward through Bethel and Albany before the melting of the ice. 

It thus appears that at North Waterford there were two valleys widely 
diverging and that glacial gravels were deposited in each valley. The val- 
ley of Crooked River is not only a slope of natural drainage, but it is also 
more nearly parallel with the general direction of the ice movement in that 
region. Yet by far the larger overflow was southwest, along a route more 
transverse to the glaciation and over a low divide, rather than down the 
drainage slope. The breadth of the gravel plain along the Crooked River 
is as great as that of the Kezar Brook series. Both series were deposited 
in channels that were probably broad enough to carry off all the waters 
that came from the north without the aid of che other channel. 

The history of the glacial gravels of this region is probably as follows: 
Originally a large glacial river flowed from Albany (and perhaps from 
Bethel and the Androscoggin Valley) south to North Waterford and along 
the valley of Kezar Brook southwestward to Lovell and thence south to the 
Saco River. At first this river flowed in a narrow channel within the ice. 
Subsequently other ridges were deposited in channels near the original one. 
By degrees these channels became confluent and the channel broadened, 
and an osar-plain was laid down in the broad channel. During this time 
the valley of Crooked River was blocked by ice, so that the glacial river 
easily flowed southwest over the divide. But the time came, toward the 
last of the Ice period, when the waters effected a passage from North Water- 
ford eastward down the valley of Crooked River. At this time the melting 
had proceeded so far that the valley was bare of ice from Sebago Lake 
north to Hast Waterford. Hence glacial gravel was formed from North 


254 GLACIAL GRAVELS OF MAINE. 


Waterford only as far south as the plain near Papoose Pond, and below 
there the water flowed as an ordinary surface stream, and only fluviatile 
drift was deposited in that part of the valley; at least, if this glacial stream 
flowed in an ice channel south of East Waterford it was so narrow as not 
to deposit gravels, or else the glacial gravels are now covered by the 
valley drift. 

Where the Albany series reached the Saco River, near East Brownfield, 
it can no longer be distinguished from the other series which cover a large 
part of southwestern Maine with a closely connected network of gravel 
plains. Above this point the drift of the Saco Valley is much finer in com- 
position than the broad plain of gravel, cobbles, and bowlderets which 
extends from this pomt south and east along the valley for many miles. In 
the middle of the valley the stones of this plain are very much worn and 
rounded, but near the sides of the plain the material resembles till, which 
plainly has had the finest detritus washed out of it, but with hardly any 
attrition. I repeatedly saw stones and bowlders near the outer margin of 
the upper terrace that retained their till shapes with only very small modi- 
fication. This appearance was especially noticeable at an excayation near 
Brownfield station of the Maine Central Railroad. 

In Hiram, Baldwin, and northern Limington the gravel plain of the 
Saco is often uneven and ridged like the plains of reticulated kames. As 
we go southward the plain becomes more level and the material finer. The 
coarse gravel gives place to fine gravel and this passes by degrees into 
broad sand plains in Standish, southern Limington, and Hollis, where the 
sand ends in the marine clays. The plains showing reticulated ridges thus 
pass by degrees into the marine delta-plains. These deltas were deposited 
not far above 230 feet in the open sea, and are the largest in Maine. 

While it is not easy, or at present possible, to separate the Albany-East 
Brownfield series from the other reticulating plains of sand and gravel near 
the Saco River in Brownfield, Hiram, Cornish, Limington, and Baldwin, 
yet the great size of the series toward the north makes it certain that this 
great glacial river contributed a large proportion of these plains. Most of 
the gravel series of southwestern Maine are remarkable for the height of the 
hills which they cross, but this series penetrates the high hills that le east 
of the White Mountains along a route so level that one may travel from 
Gorham, New Hampshire, eastward to Bethel, and thence along the course 


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ALLUVIAL TERRACES OF SACO RIVER. 2955 


» of this series, without having to rise over hills higher than 100 feet, measured 
on their northern slopes. 


ALLUVIAL TERRACES OF THE SACO RIVER. 


From the sea to near Bonny Kagle, in Standish, the Saco River is bor- 
dered by terraces of erosion in the marine beds.. Near the river these 
marine sediments differ but little from those found at a distance from the 
river. If the ice had melted before the marine beds were laid down and 
the sea advanced, the river would have begun to flow before the deposition 
of the clays, and we should now find a plain of valley drift overlain by the 
marine beds. The fact that these beds are substantially the same near and 
far away from the river valleys shows that the rivers had not begun to flow 
at the time of their deposition, and that they were a rather deep-water 
formation. 

Near Bonny Eagle the Saco enters the great marine deltas brought 

‘down by the glacial rivers, overlain by the delta of the river after the melt- 
ing of the ice That the glacial deltas were deposited in the open sea is 
proved by the fact that they are confluent and practically continuous over 
a broad area extending from Standish southwestward through Limington, 
Hollis, Lyman, Waterboro, Alfred, and Sanford, to North Berwick. For a 
few miles above Bonny Eagle the erosion terraces of the Saco are exca- 
vated in sand overlying clay. Then the gravel appears, and above Steep 
Falls coarse gravel, cobbles, bowlderets, and some bowlders form a large 
part of the river terraces. Where there are broad plains of porous gravel 
bordering the river there is usually more erosion than in the narrow parts 
of the valley. This is due largely to the action of subterranean waters in 
the manner elsewhere described. 

North of Hiram le a number of broad, rather level valleys opening 
southward. This would tend to converge the ice into the narrower valley 
of the Saco extending from this point south and east. Late in the Ice 
period as the ice retreated there would naturally be a local glacier in the 
valley, i e., one following the valley independently of the previous general 
movement. It is a difficult problem now to determine how much of the 
deep sheet of water-assorted matter that covers the Saco Valley from 
Hiram to Steep Falls was deposited during the general movement and how 
much was the work of the more local glacier. As the ice retreated up the 


256 GLACIAL GRAVELS OF MAINE. 


valley the terminal moraine of this supposed glacier would naturally fall * 
into the subglacial rivers and be modified by water, thus helping to form 
an overwash or frontal plain in front of the ice as it receded. 

Above Hiram the part of the valley covered by alluvium broadens 
into a plain, in Brownfield and Fryeburg, near 10 miles in diameter. The 
floods of valley drift in time covered the whole of this broad area, so that 
it would present the appearance of a lake. In this was deposited a broad 
fluvial delta extending from Conway, New Hampshire, east to Lovell and 
Brownfield. For many miles in this broad sedimentary plain the river 
winds very circuitously and is bordered by only a single bluff of erosion— 
that which forms its banks. This indicates that erosion and deposition are 
here going on at about the same rate. The alluvial plain narrows as we 
approach the New Hampshire line, and the drift becomes coarser and con- 
tains much rounded gravel. The erosion terraces along the Saco River 
vary from 10 to about 50 feet in height above the river. 


THE GREAT COMPLEX OF NORTHWESTERN YORK AND SOUTHWESTERN 
OXFORD COUNTIES. 

This is a series of plains closely connected by lateral series so as to 
cover as with a network the hilly country lying west and southwest of the 
Saco as far as the valley of the Mousam River. In this complex series it 
is difficult to distinguish tributary from delta branches. On the west these 
gravels are connected by three lines of gravel plains with the great kame 
system deseribed by Mr. Warren Upham in the reports of the New Hamp- 
shire geological survey as extending from Conway, New Hampshire, south- 
ward to the valley of the Ossipee Lakes. Two of these plains Gn the 
form of osar-plains about one-fourth of a mile wide) extend from Effing- 
ham, New Hampshire, into Parsonsfield, Maine, while a tract of reticulated 
ridges nearly 3 miles wide passes from Wakefield, New Hampshire, into 
Newfield and Acton, Maine. 

The region between the Saco and the Mousam is diversified by numer- 
ous ranges of hills. If we start south from the broad hill-encireled plain 
of Fryeburg, which on a small scale much resembles in form the “parks” of 
the Rocky Mountains, we almost immediately enter the hilly country. In 
Porter, Brownfield, Parsonsfield, and Cornish many of the higher hills rise 
to 800 feet or higher, and the slopes are rather steep. Going southward, 
we find the valleys becoming broader and the hills lower and with gentler 


COMPLEX IN YORK AND OXFORD COUNTIES. 257 


slopes. Not far from the line of the Portland and Rochester Railroad we 
pass into a gently rolling plain, out of which rise a few granite knobs and 
other hills, ike Bauneg Beg and Agamenticus. This plain extends to the 
sea. In the tract of country here described there is no single dominant 
range of hills. There are two systems of valleys, nearly at right angles 
to each other. The larger streams, such as the Great and Little Ossipee 
rivers, flow eastward into the Saco. The north-and-south valleys are 
occupied by numerous lateral tributaries of the principal streams. This 
arrangement of valleys will in part account for the somewhat rectangular 
shape of some of the reticulations of this complex series. The local rock 
of this region is chiefly granitic, and this rock in Maine always affords an 
abundance of till. In the more hilly country the glacial gravel is in gen- 
eral quite coarse, containing multitudes of much-rounded bowlderets and 
bowlders up to 4 feet in diameter. Broad sheets of rounded gravel, ete., 
frequently have numerous large till-shaped bowlders resting upon them, 
but these are mostly below 230 feet, and may have been deposited by ice 
floes. Numbers of short tributary branches come down the slopes of hills 
to join the main plains, and even these short hillside branches show large 
rounded bowlders. Along the principal lines of glacial overflow the stones 
are much worn and rounded, yet here and there they are subangular and 
differ in shape but little from those of the till. Such areas are usually on 
the borders of the plains. 

The number and height of the hills which the gravels of this region 
cross are remarkable. Nowhere else in Maine is there anything equal to 
them. In Brownfield, Porter, and Hiram the glacial rivers flowed up and 
over these hills 200 or more feet higher than the valleys to the north of 
them, and in Parsonsfield and Cornish they crossed several more. In Lim- 
ington, near the Cornish line, a gravel series goes up and over a pass in a 
narrow valley called “The Notch,” at the western base of Strouts Moun- 
tain. The top of the pass is fully 300 feet above the northern base of the 
hill and about 400 feet above the same gravel series at the Saco River, 2 
or 3 miles north of The Notch. These measurements were made with the 
aneroid barometer, but I have tried to make the figures here given under 
the truth rather than over it. Near the tops of the higher hills the gravel 
is scanty, and then for a half mile or more sometimes none will be found 


on the southern slopes. These branching series often reject valleys of 
MON XXXIV——17 


258 GLACIAL GRAVELS OF MAINE. 


favorable slopes in order to climb hills, and are therefore difficult to map. 
Delta branches are liable at any point to diverge from the series one is 
exploring, and constant watchfulness is required. ~ 

The map shows the courses of these connected series more clearly 
than any verbal description, yet in the absence of maps showing the relief 
forms of the land it may be best briefly to describe the glacial gravels of 
three townships as a specimen of the whole region now under consideration. 

Near the southern end of the Fryeburg Valley the glacial gravels 
begin, and extend southward along a low pass between the conical peaks 


eS a BS 
~ 


Fia. 24.—Broad osar penetrating narrow pass over hill 400 feet high; Limington. 


known as Tibbitts and Peavys hills. The line of gravels ihen descends 
about 100 feet into the east-and-west valley of Pequawket Stream. It 
here divides into three delta branches. One series crosses the valley 
nearly at right angles and ascends the long hill which lies to the south 
along the south branch of Pequawket Stream to a height of fully 200 feet. 
Another branch turns east and follows the Pequawket Valley through 
Brownfield Village, when it soon expands into a broad plain reaching to 
East Brownfield, southeast of which place it becomes confluent with the 
gravels of the Albany-Saco River series. This plain shows the horizontal 


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COMPLEX IN YORK AND OXFORD COUNTIES. 259 


assortment of sediments characteristic of the delta-plain, and this broad 
and level valley near East Brownfield was at one time occupied by a lake, 
or a river so broad as to resemble a lake. The third diverging branch 
turns southwest and goes up the main Pequawket Valley for somewhat 
more than 2 niles, when it again parts into two series, one of which goes 
nearly south over a high hill and thence to Porter Village, while the other 
ascends a hill toward the southeast and, when near the top of a pass situ- 
ated at the northern base of Pine Hill, unites with the series which follows 
the south branch of the Pequawket Stream. The united series now con- 
tinues southeast through the pass and descends 180 feet into a valley open- 
ing eastward. By followmg down a rather steep slope in this valley the 
glacial river might, within 2 miles, reach the very large glacial river which 
flowed southwest from East Brownfield to Kezar Falls along the valley of 
Tenmile River and through the remarkable valley in the western part 
of Hiram called The Notch. Instead, it turned at a right angle southward 
and climbed a hill 180 feet high. On the top of this hill the river was in 
a situation interesting to study. Right in front of it is a valley leading 
southeast into The Notch, and by taking this route the glacial stream might, 
within 2 miles, have joined the glacial river just mentioned at a point 250 
feet or more lower than its position on the hilltop. Instead of following 
this valley along a down slope, the glacial river turned southwest, and for 
an eighth of a mile flowed directly on the top of the ridge, and then crossed 
a north-and-south hill over a col 30 feet high. The gravels are somewhat 
discontinuous south of this point, but can readily be traced along the 
western slopes of this hill to Kezar Falls. 

The above description applies to an area only about 10 miles long 
from north to south. A minute description of the branchings and reticula- 
tions and other developments of the Saco-Mousam network of gravel plains 
must be omitted. 

But there is one line of gravels that demands further notice. The 
Notch, in the western part of Hiram, is a very low valley with U-shaped 
cross section. The level portion at the bottom is usually not more than 
one-fourth of a mile in breadth, and at the highest part of the pass it is 
hardly an eighth of a mile wide. From this point two streams flow in 
opposite directions. One of them is a branch of Tenmile River; and 
flows northeastward into the Saco River; the other flows. southwestward 


260 GLACIAL GRAVELS OF MAINE. 


into the Great Ossipee River near Kezar Falls. A line of glacial gravels 
extends from East Brownfield along The Notch to Kezar Falls. In the 
midst of The Notch are three ponds bordered by plains of glacial gravel 
rising up to 20 or more feet above the water. It is difficult to account 
for lake basins being excavated by boiling springs im a mass of coarse 
composition such as gravel, cobbles, and bowlderets. These lake basins 
must have been deposited in substantially their present shapes by the 
glacial river. This is an interesting divergence from the ordmary type 
of osar-plain. Here, as in numerous other places, we find the broad osar 
and the tracts of reticulated ridges passing into each other by degrees. 

I shall sum up, briefly, some of the general features of the glacial 
gravels of this region. 

Seldom, and then only for a short distance, do the gravels take the 
form of a single ridge with arched cross section, like the osars of eastern 
Maine. Toward the north these gravels usually take the form of a broad 
osar, i. e., a rather level-topped plain from a few rods up to one-fourth or, 
in a few cases, one-half mile wide. Farther south, at elevations below 600 
and above 230 feet, the gravels expand into plains of reticulated kame 
ridges up to 3 or 4 miles in breadth. At about 230 feet the reticulated 
kames pass into the great level delta-plains. These show clearly the hori- 
zontal classification of sediments characteristic of deltas, and sand plains 
pass by degrees into marine clays. Here and there small delta plains are 
found in the courses of both osars and reticulated kame plains. Many of 
these are far above the contour of 230 feet and were probably deposited 
in glacial lakes. 

One who studies the glacial gravels only on southern slopes where the 
rivers now flow in the same direction and in the same valleys as the glacial 
rivers, will find it difficult to distinguish between the sediments of the two 
kinds of rivers in such situations. He may come to attribute all the allu- 
vium to the rivers of the so-called Champlain period, and may even doubt 
the existence of glacial rivers, at least as agents for depositing alluvium so 
much resembling fluviatile drift. Such skepticism will be permanently 
removed by a few days of exploration in the region now under considera- 
tion. Here he will see these long lines of sand, gravel, and coarser sedi- 
ment go up and over the steep hills. Here can be seen how often they 
reject valleys of natural drainage and instead climb hills 200 feet or more 


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COMPLEX IN YORK AND OXFORD COUNTIES. 261 


high, leaving vast deposits of water-assorted matter on hillsides where there 
never could be any running water except rain-water rills (see Pl. XXII). 
Here these gravel plains divide into diverging series which after a time come 
together again. By the time the observer has seen all this he will be ready 
to admit that these gravels are wholly inexplicable as the result of fluvia- 
tile, lacustrine, or marine action. In the midst of these winding valleys bor- 
dered by high hills and covered by water-rounded cobbles, bowlderets, and 
_bowlders, showing the action of swift currents from the north, and in pres- 
ence of the meandering lines of gravel, wandering about on the tops of 
hills, the iceberg theory of the glacial drift of Maine utterly breaks down. 
These circuitous gravel systems bearing such curious topographical rela- 
tions become of themselves one of the strongest proofs of the existence of 
the ice-sheet over Maine. Glacial ice accounts for the barriers necessary 
to force streams over hills and to prevent them from flowing downhill by 
the steepest slopes. No other known drift agency can do this. The critical 
student of the great northern drift should by all means visit this region. 

On the map the glacial gravel of this region is marked as ending on 
the north a short distance southeast of Fryeburg Village. North of this 
point lies the large level basin of Fryeburg, Lovell, Stowe, and Stoneham, 
inclosed by high hills. To the west and northwest lie the White Mountains 
and their outlying ranges. During the last days of the ice this level valley 
would be filled by a sort of local glacier, replenished from the north and 
west along valleys where the flow of the ice could continue after the move- 
ment over and across the hills lying to the north had ceased. Here would 
be a local tongue of ice filling a valley about 25 miles long and from 3 to 
5 miles broad. In all this valley I have not found a deposit of unmistak- 
able glacial gravel. Cold River originates among the eastern spurs of the 
White Mountains and flows southeastward into the Saco River. Its valley 
would be a favorable place for a glacial stream, but the alluvium in the 
valley is very different from the gravel here described as glacial. The 
stones are subangular and the drift is clearly fluviatile. The apparent 
absence of glacial gravel from the level Fryeburg basin, while it is so 
abundant in the hilly country to the south, will be further discussed in a 
subsequent chapter. 

South and east of the Portland and Rochester Railroad the country 
was wholly under the sea as far as the New Hampshire line, except a few 


262 GLACIAL GRAVELS OF MAINE. 


ranges of hills which then formed islands. A large part of the sands and 
gravels of this region were deposited in the sea, mostly in the open sea in 
front of the ice, but in part in broad channels opening on the sea-like bays 
inclosed at the sides by ice. In this region the gravels are somewhat dis- 
continuous, and many of the smaller deposits are more or less covered by 
the marine clays; they are therefore difficult to trace. T have only partially 
explored the southern portion of York County. 


ACTON-NORTH BERWICK SYSTEM. 


This series of gravels is provisionally described as a distinct system, 
though this glacial river may have joined that which flowed down the 
Mousam Valley. If so, it was early in the Ice age, and late in that period 
these streams poured into the sea by widely separated mouths. The system 
begins about a mile north of South Acton, on the southern slope of a high 
hill. For about 2 miles it consists of two nearly parallel series situated 
about one-fourth of a mile apart. One of them is a series of short ridges 
and hummocks, forming a single line like the osars, with only a few out- 
lying and reticulated ridges. These gravels run southeast across the valley 
of a stream which flows eastward into the Mousam River. It then pene- 
trates a narrow pass through the hills southward over a divide not more 
than 50 feet high. In this pass a small stream soon appears, which flows 
southward past East Lebanon, and the gravel system follows the same val- 
ley, most of the way as a narrow osar-plain, now much eroded by the 
stream. It passes near Lebanon station of the Portland and Rochester 
Railroad and about a half mile west of Bauneg Beg Mountain, and con- 
tinues south and east through North Berwick into Wells. As already 
stated, the system near South Acton is double. The more western gravels 
begin near the other series, but keep about 100 feet above it on the hillside. 
They take the form of a small two-sided ridge or osar with very steep lat- 
eral slopes and a very meandering course. ‘The material is but little water- 
worn. Within about 2 miles it comes down the hill to near the other series 
in the valley, and is then lost. No doubt it was deposited by a small tribu- 
tary of the main glacial river. This little osar-ridge is situated 400 feet or 
more above the sea, and the difference between its steep side slopes and the 
low arch of the ridges found below 230 feet is very noticeable. 

From East Lebanon southward this system traverses a gently rolling 


U. S. GEOLOGICAL SURVEY MONOGRAPH XXXIV PL. XXIII 


A, PLEXUS OF KAME RIDGES AND MOUNDS; NEAR NORTH ACTON. 


B. TERMINAL MORAINE; WINSLOWS MILLS, WALDOBORO, 


‘ 


— 


LEBANON AND WEST LEBANON SYSTEMS. 263 


plam. Here and there are reaches of level osar-plain, but for most of 
this distance the gravel takes the form of a plain of reticulated kames 
one-eighth of a mile or more wide. The system passes not far west of 
Bauneg Beg Mountain, and expands into a marine delta not far north of 
North Berwick Village. South and east of this point are some discon- 
tinuous plains of sand and gravel, but their connections are obscure. 
Maryland Ridge, in Wells, is a large and broad ridge of glacial gravel 
having a southeast direction. I provisionally mark it as a part of this 
system, though possibly connected with the great series that extends from 
Conway and the Ossipee Lake region, in New Hampshire, down the 
Mousam Valley past Sanford. 


LEBANON SYSTEM. 


A series of somewhat discontinuous and plain-like gravels extends 
from near Wentworth or Northeast Pond, and in the northwestern part 
of Lebanon, southward through the central part of Lebanon, following a 
rather low pass and then the valley of a stream that passes near South 
Lebanon. Toward the south there are several narrow plains, which 
diverge in direction, as if delta branches of this system. These have been 
traced by me only a short distance into Berwick. I am indebted to Mr. 
J. H. Hammond, of Sanford, for much information regarding this portion 
of York County. 


WEST LEBANON SYSTEM. 


This gravel system begins on the east side of Salmon Falls River a 
mile or two north of East Rochester. It crosses into New Hampshire near 
East Rochester, and is said to extend to Dover, New Hampshire. 


Coy Age ata’ 


CLASSIFICATION AND GENESIS. 


Although we need not now study the causes of such astonishing vari- 
ations in climate as have taken place in post-Tertiary time, we must assume 
an ice-sheet covering all New England except perhaps a few of the highest 
peaks. For the present we must investigate the order of events. The 
higher questions involving the causes of geological climates must come 
later. As it is the first office of science to classify facts and discover their 
underlying principles, it remains for us to make a detailed examination of 
the known facts and, if possible, to reach a satisfactory classification and 
explanation of them. The moment we enter upon this inquiry, however, 
we confront the difficulty of isolating the glacial sediments from the other 
glacial deposits or from other forms of water transportation, and our subject 
at once broadens so as to include every form of superficial deposit. 

Probably northern Greenland typifies more nearly than any other 
known country the condition of New England at the time it was. covered 
by ice. It is known that the interior of that country is covered by a great 
continuous snow field that rises above all the hills and most of the moun- 
tains and is discharged into the sea by broad glaciers. During the greater 
part of the Ice age the glaciers of New England were practically confluent. 
The ice then extended far out into the present Gulf of Maine, and was there 
discharged into the ocean as icebergs or as melting waters. The drift 
which was at that time deposited near the ice front is now beneath the 
Atlantic. But the last part of the Glacial period saw the extremity of the 
retreating ice confronted by the sea along a very crooked line situated over 
what is now the dry land. The sea then stood at about 230 feet above its 
present level, and broad arms of salt water extended far into the interior of 


the State along the principal valleys. Our problem involves both the study 
264 


PREGLACIAL LAND SURFACE AND SOILS. 265 


of the geological work of the ice on the land of that period and also the 
offshore drift then thrown into the ocean by the ice-sheet itself, by ice floes 
and icebergs, and by glacial rivers, the whole having since been more or 
less modified by the waves and currents of the sea. The subsequent 
retreat of the sea to its present position has exposed these deposits for 
convenient study, and thus has furnished a good example of the multi- 
form work going on off an ice-bound coast. Our geological conceptions 
are thus enlarged by the same process that added the clay loams to the list 
of the soils of Maine. But the problem before us involves more. The 
final melting of the ice over the land left the waters free to follow the val- 
leys of natural drainage. Rivers much larger than the present rivers then 
flowed into the sea from 30 to 100 miles above their present mouths and 
were depositing deltas im the sea not far from the coast line as it at that 
time existed. These deltas are now exposed for our study, and are to be 
distinguished from marine and glacial sediments. Moreover, before the ice 
had all melted, lakes gathered on the land, confined wholly or in part by 
ice. Thus the various kinds of drift of the glacier are to be distinguished 
in the midst of preglacial soils and lacustrine, fluviatile, and marine sedi! 
ments, often since modified by the action of the wind and streams, or 
strewn by drift from floating ice, or eroded in part and carried away beyond 
our sight, or bodily misplaced by landslips. Everything which directly or 
indirectly produced a single one of the field phenomena must be of 
interest to us. 


PREGLACIAL LAND SURFACE AND SOILS. 


The longer a region has been above the sea the more nearly are the 
surface features due to upheaval and unequal elevation replaced by those 
due to subaerial erosion. The coming of the ice-sheet found Maine in that 
stage of development called geological ‘old age.” The land had been 
deeply sculptured, here with a heavy stroke, there with a lighter touch, and 
the rock yielded in different degrees to the attack of the chisel. Only the 
ruins of the folds and cones produced by mountain-making forces remained. 
The outlines of these remnants of a primeval land were about like the 
present surface forms of the State, save that the hills were more rough and 
angular in outline. Steep cliffs of erosion abounded which were ragged 
with weather-rounded bowlders. The long conflict which for geological 


266 GLACIAL GRAVELS OF MAINE. 


eons had been going on between the elements and the living rock was 
testified to by the towers and buttresses with which the rock in vain 
strengthened its scarps of erosion. While the outlines of the hills were not 
so beautifully curved as at present, the drainage basins and the relative 
height of hill and valley were probably about the same. 

It is uncertain to what depth the rock had become weathered in 
preglacial time. Over the driftless area of Wisconsin the residual earth 
has been found by Chamberlin and Salisbury to have a thickness of 4 
feet. Ina region of granitic rocks the residual earth represents but a small 
part of the rock which has become shattered and more or less disintegrated. 
In the Biue Ridge of Virginia I have repeatedly seen railroad cuts where 
the Archean schists were weathered and fractured to a depth of 20 to 30 
feet. In Maine the roofing slates weather with such extreme slowness that 
the preglacial soil may have been on the average only a few inches thick, 
and the weakened rock only a few inches more. The sedimentary sand- 
stones, ete., may have had only about the same depth as in the driftless 
area of Wisconsin, but the crystalline and schistose rocks must have been 
weathered to a much greater depth. Many of the feldspathic rocks have 
become weathered to a depth of several inches to several feet in postglacial 
time, and this indicates a deep preglacial sheet or surface layer of soil, 
subsoil, and bowlders of decomposition. Obviously the actual depth 
attained depends on the ratio between weathering and transportation. The 
till is much more abundant in the regions of schistose rocks than in those 
of slates and sandstones. This of itself is a proof of a greater depth of 
weakened rock, and in the granitic regions there was a still greater depth. 
Judging by the cliffs on the south side of Russell Mountain, elsewhere 
described, I do not think it an extravagant estimate that the rock in pre- 
glacial time had there become fractured into blocks removable by the ice 
to a depth of 50 feet. This was in granite, and not a very easily weathering 
variety. The depth of rock which had become fractured and more or less 
weathered in preglacial time may be estimated at from a few inches up to 
perhaps 50 feet. 

Since the land had been for a long time above the sea, the larger 
valleys would have attained a base-level of erosion. Lakes occupying rock 
basins, if there had been any, would have been silted up or have been 
drained by the cutting down of their inclosing barriers, or in case of shallow 


PREGLACIAL LAND SURFACE AND SOILS. 267 


basins they may have been filled with peat. In the valleys there would be 
much stream wash—silts, sands, and gravels. I have never given up hope 
that somewhere portions of these preglacial soils, peats, or lake sediments 
were enabled to survive beneath the rough ridings of the ice-sheet in masses 
sufficiently large to contain characteristic fossils and be recognizable. So 
far as yet discovered, the only bodies of preglacial soil that failed to 
be incorporated with the drift of the ice-sheet were contained in small 
depressions of the rock. They consist mainly of rock weathered in situ, 
and plainly underlie the glacial drift. They are much the oldest of the 
superficial deposits of Maine. The largest of the depressions of this kind 
in which the primeval soils are preserved were in argillitic and quartzitic 
schists, and were less than 7 feet in diameter, unless certain narrow east- 
west ravines in sedimentary rock that open out from the gorge of the 
Seboois River not far from Mount Katahdin be also of this kind. The pro- 
jecting tongues left by the unequal weathering of the fine-grained schists 
were thin and easily broken. Hence these rocks were reduced by the 
glacier to such an even or gently undulating surface that their glaciation 
may well be termed planing. The mica- and other coarse schists yield fewer 
areas of preglacial weathering, and these only from 1 to 3 feet in diameter. 
The laminze are thicker and vary much in hardness. The glaciated rock 
often shows undulations a few inches wide and from 1 to 3 inches high, so 
that the surface has a ribbed appearance, as of corduroy. The projecting 
ribs are rather parallel to the strike of the laminz of schists, and more often 
are transverse to the glaciation. Where the furrows between the ridges are 
very large they have sometimes been described as grooves gouged out of 
the rock by a single bowlder. Where they happen to be parallel with the 
glaciation it is difficult to decide the question of their origin; but where 
they are parallel with the lamination of the rock and transverse to the 
glaciation, as they usually are, they must be regarded as due to the condi- 
tion of the weathered rock as the ice began to act upon it. The ridges are 
the projecting edges of the harder layers which the glacier was not able to 
plane off to a flat surface, although removing the weakened rock and leaving 
the surface of both the ridges and the hollows thoroughly polished. In 
other words, in these cases the signs of the surface of preglacial weathering 
were not entirely obliterated. 

The granites and syenitic granites are glaciated in still more irregular 


268 GLACIAL GRAVELS OF MAINE. 


surfaces. They show greater numbers of rounded bosses, or roches 
moutonnées, and many small rock basins. These depressions are glaciated 
even to the bottom. I have not been able to find in granite areas surfaces 
of preglacial weathering, except at certain cliffs facing the south. For 
instance, at the southern brow of Russell Mountain, in Blanchard, there is a 
steep cliff several hundred feet in height. The upper portion has been 
shattered by the elements into a wall of bowlders of decomposition, most 
of them still occupying their original relative positions. Some of the 
largest of the upper tier of bowlders have been moved several feet south- 
ward, so as almost to cause them to fall down the cliffs. The top and 
northern slopes of the hill are intensely glaciated, and they so far bore the 
brunt of the attack that the ice only partially succeeded in pushing these 
bowlders from their places. Doubtless on that cliff im preglacial time there 
rested many a bowlder which the ice was afterwards able to push over the 
brink and carry away. The turrets and battlements of the castle as the 
glacier found it have been cut off, and perhaps the upper stories, but 
enough remains to remind us that the power of ice has some limit. 

The condition of the surface of the glaciated rock in Maine proves 
that the behavior of a thin glacier, such as the extremities of those of 
Switzerland and Norway to-day, is very different from that of one a half 
mile or more in thickness. Under the deep ice of the time of maximum 
accumulation only here and there a small depression became filled by sub- 
glacial till or by embayed ice, so that the glacier flowed over it as if it had 
been solid rock. We have seen that the bottoms of most of the narrow 
furrows were glaciated even when transverse to the direction of the motion. 
It was very different during the last of the Glacial period, when the ice had 
become thin. Thus, at one of the lime quarries at Rockland, in a north- 
east and southwest valley, there is an earlier series of long, straight 
scratches bearing S. 81° W. Later scratches are found which in places 
have obliterated the earlier ones. They bear 8. 51° W. The smooth, 
even surface of the limestone ledge gently inclines southwestward about 
1 foot in 40. On this incline there is a steeper place where within 3 feet 
there is a fall of 3 or 4 inches. The later scratches come up to the northern 
edge of the steeper incline, when they disappear for about 3 feet, then begin 
again near the foot of the steep incline and continue southward. The 
steeper slope is beautifully glaciated, but the scratches were made during 


GREENLAND SNOW AND ICE. 269 


the earlier glaciation. Here at the time the later scratches were made the 
ice could not bend downward so sharply as the small change in direction of 
slope. In other words, the ice traveled 3 feet horizontally, held up by its 
cohesion, before it would bend downward 3 inches. On the other hand, 
the earlier scratches changed instantly with the slope, and they themselves 
were a deflection from the general glaciation of the region in which they 
are found, and probably were not made at the time of greater thickness of 
ice. All over Maine the earlier scratches bend sharply (in vertical planes) 
around curves and some pretty sharp angles. Such facts prove that 
deductions drawn from the behavior of thin glaciers do not in all respects 
apply to thick ones. And yet if a thin glacier can not at once bend its 
course downward under the force of gravity, it is evident that the same 
causes, but operating under different circumstances, will limit the power of 
even a great ice-sheet to flow down into cavities and glaciate them. The 
ice, as shown elsewhere, must have been less than 200 feet thick at the 
time of the formation of the Waldoboro moraine. The pressure on its bed 
(neglecting the weight of moraine stuff) was less than 6 atmospheres. If 
the thickness of the ice over Maine was only half a mile, the pressure at the 
base was at least 84 atmospheres. Under this enormous pressure the 
power of the ice to flow down into hollows was very great, but not unlim- 
ited. Here and there a small portion of that ancient surface was protected 
by a curve of the rock. 


GREENLAND SNOW AND ICE. 


The only region sufficiently explored to enable us to identify its con- 
dition with that of northern New England in the time of the ice-sheet is 
Greenland. Most of what we know of the condition of the interior is due 
to the labors of the Danish geologists, of Torell, Nordenskjold, and Holst 
of Sweden, of Lieut R. E. Peary of the United States Navy, and others. 

The principal facts relative to the ice and snow of Greenland likely to 
be of use to us in the interpretation of the facts as exhibited in Maine are 
the following: 

The eastern coast is bordered by much shore ice. Near the southern 
extremity the country is mountainous, and numerous glaciers occupy the 
interior, but none reach the sea. Going north the inland ice descends lower 
and the principal fiords serve as the outlet of glaciers, which come down 


270 GLACIAL GRAVELS OF MAINE. 


to the sea level and end in cliffs near the heads of the fiords, where the ice 
breaks off as icebergs. Still farther north these glaciers extend out nearly 
to the mouths of the fiords, and they become broader. Finally the glaciers 
become confluent in great ice-sheets that confront the sea in a solid and 
continuous wall for a hundred miles or more. Part of this great breadth is 
due to the climate, part, perhaps, is due to the form of land surface. Going 
from the coast inland we find the ice surface rapidly rising. Near the shore 
the ice usually barely fills the valleys, leaving the mountains bare. Inland 
only a short distance, we find but few peaks (munatakker) projecting 
above the ice. Within 30 or 50 miles we reach a region where even the 
highest peaks are wholly beneath a great continuous ice-and-snow field. 
In the interior no moraine stuff appears on the surface of the ice, though 
there is more or less dust, the kryokonite of Nordenskjold. Some morainal 
matter falls from the nunatakker onto the ice as we approach nearer the 
margin, but near the extremity many stones and bowlders appear on the 
surface. Many of these are in situations where they are supposed not to 
have fallen on the surface from nunatakker, but have got up into the ice 
from below, and were subsequently exposed by the melting of the ice or 
by movements within the ice. These are glaciated little or not at all. In 
several places the Danish geologists have seen a ground moraine, as, for 
instance, where a thin flow of ice takes place over the cols between two or 
more nunatakker while the deep mass divides and flows around them. The 
two main streams unite a short distance below the buried ridge. In lee of 
the buried ridge a moraine is formed, brought over by the thin sheet. The 
material of this moraine is intensely glaciated. In some cases a moraine 
profonde has been seen beneath the ice near its extremity.’ 


THE TILL. 


While in general the unmodified glacial drift, or till, rests upon the 
preglacial soils and the glaciated rock, yet there are local exceptions where 
a later deposit rests on the rock in consequence of the absence of till or 
the occurrence of landslips. Indeed, landslips have been so common that 
it is unsafe to trust any inferences as to the chronological order of events 


1 This account is condensed from the above-mentioned authors, quoted by J. E. Marr in Geol. 
Mag., April, 1887. 

Since the above was written a paper on Holst’s observations in Greenland has been published 
in the American Naturalist (July and August, 1888), by Dr. J. Lindahl. 


THR TILL. Beit 


until it is clearly proved that there have been no slides at the places of 
observation. 

A fundamental question regarding the till relates to its origin. The 
hypothesis of Torell—that part of the morainal matter of the ice-sheet was 
beneath the ice, while the upper portion was distributed through the lower 
part of the ice—has since 1877 appeared to me to explain satifactorily the 
facts as observed in Maine. The principal considerations bearing on the 
subject are the following: 

We do not know how the age of ice began. Looking at it from the 
standpoint of our present climatic conditions, it would most naturally come 
on gradually. After a time local glaciers filled the mountain valleys. 
Above them rose cliffs that had been rent into loose blocks during the long 
ages preceding. Much of this cliff débris fell down upon the ice and 
formed moraines like those of the Alpine glaciers. But more snow con- 
tinued to fall than melted, and the time came when this morainal matter 
and the hills were overtopped by the snow and ice. Unless the higher 
peaks of the White Mountains and Mount Katahdin be exceptions, all the 
territory was covered. he proof of this is conclusive, since the rocks on 
the hills are scored and aftord drift bowlders transported from the north. 

So, too, during the decadence of the ice-sheet the tops of the higher 
hills appeared above the ice long before the flow in the valleys ceased. The 
glacier had just swept over the cliffs and removed most of the talus and 
bowlders of decomposition; few therefore would fall upon the ice. The 
melting of the upper portions of the ice would leave many bowlders on 
the higher and steeper parts of the hills in such unstable equilibrium that 
now and then, as one was freed from the embrace of the ice, it would roll 
or slide down the slopes onto the ice that still remained in the lower parts 
of the valleys. At this time landslides of the freshly deposited material 
would naturally be frequent. In these ways it may be admitted as possible 
that morainal matter was at this period precipitated from above upon the 
ice, after the manner of ordinary valley glaciers. But if moraines were 
thus accumulated we ought now to find them, in the form of ridges and 
trains of bowlders, especially at the flanks of the high, steep hills. On 
the contrary, the bowlder trains are in lee of granite knobs, where a cliff 
was shattered beneath the ice and its bowlders pushed forward. While, 
then, we may grant a limited fall of débris from above onto the top of the 


272 GLACIAL GRAVELS OF MAINE. 


ice during the beginning and near the end of the existence of the ice-sheet, 
yet this supposed moraine stuff is not now so distinctly arranged in the 
form of medial or lateral moraines as to warrant the assertion that any 
considerable amount ever fell upon the ice from above. And it is therefore 
practically self-evident that during the time when all the country was coy- 
ered with ice the morainal matter could get into the ice only from beneath. 


MORAINAL DEBRIS OF THE ICE-SHEET. 
MORAINE STUFF IN THE LOWER PART OF THE ICH. 


That till matter had in some way worked up into the lower part of the 
ice is conclusively proved by the presence of several terminal moraines. 


WALDOBORO MORAINE. 


The largest of these terminal moraines extends from near Winslows 
Mills, Waldoboro, for about 6 miles north and eastward. Its general 
appearance is that of a two-sided ridge, or sometimes of two or three 
roughly parallel ridges. It is composed of the same kind of matter as the 
upper layers of the till of the surrounding region, unless perhaps it has had 
a small proportion of the finest rock flour washed out of it by very gentle 
currents. 

Regarding this moraine it may be said: 

1. The moraine is not composed of matter torn up from the ground 
moraine or previously deposited till and pushed forward by the snout of 
an advancing glacier. As elsewhere recorded, a series of hummocks and 
short ridges of glacial gravel extends from Waldoboro northward along the 
Medomae Valley to a point more than a mile north of the moraine. One 
mound of this series directly underlies the more northern of the two ridges 
at Winslows Mills. If the ice during an advance had been-able to push 
before it so large a ridge composed of till previously laid down on the bare 
earth, it ought to be able to push before it the heap of glacial gravel now 
found beneath the moraine, as well as all the other eskers situated north of 
this point. But no esker material appears in the moraine—only ordinary, 
slightly water-washed till. Also, the external forms of the eskers north of 
the moraine differ little if any from those situated south of it, so far as I 
could discover. 


U. S. GEOLOGICAL SURVEY MONOGRAPIHH XXXIV PL. XXIV 


B. TOP OF TERMINAL MORAINE. 


WALDOBORO MORAINE. BUS 


2. During the gradual shrinking of a glacier no frontal morainal ridge 
can be formed. The morainal matter is left scattered promiscuously over 
the field of retreat. 

3. When the rate of flow of the ice equals or nearly equals the rate of 
melting at the ice front, a rather steep ridge must form at the end of the 
glacier. 

It thus appears reasonably certain that the Waldoboro moraine was 
not formed during an advance or recession of the extremity of the ice, but 
during a time when the rate of advance or flow of the ice at that point very 
nearly equaled its rate of melting. South of Winslows I have found no 
similar ridge. It is a fair inference that during the time previous to the 
period of this frontal moraine the ice had been melting faster than it was 
replenished by flowing ice from the north. Here for a time the two rates 
were nearly equal, allowing, however, for two or three little periods when 
the ice receded a few rods and then held its own again. Then the rate of 
melting gained on the rate of ice flow, and as the front retreated northward 
the country was covered with a diffused sheet of till. 

To the north of this moraine lies a gently rolling plain for a few miles, 
and then we come to a range of round-topped hills rising 500 to 800 feet 
above the sea. This plain would be rather favorable to the flow of ice south- 
ward up toa very late date. The moraine crosses several hills. Its highest. 
point is about 150 feet above tide water. At this point it crosses the north- 
ern spur of a hill which toward the south rises near a hundred feet higher than 
the moraine. If the ice had much exceeded 150 feet m thickness, it ought 
to have reached a higher point on the hill than it did.’ If we assume a 
thickness of less than 200 feet of ice at the time of the formation of the 
moraine, we must admit that it is probable the higher hills of Washing- 
ton and Liberty, situated north of this place, rose above the surface of 
the ice at that time. If moraines then formed on the ice from matter slid- 
ing down from the hills, we ought now to find lateral moraines bordering 
the valleys that lie between these hills, and thence extending south to the 


‘ Observations in Greenland and by Russell in Alaska prove that when a rock or hill rises in the 
midst of a glacier the ice is driven far up the stoss side of the obstruction, sometimes to a height of 
several hundred feet. If this sort of action took place at the hill crossed by the moraine east of 
Wiuslows Mills, the thickness of the 1ce may have been even less than the above estimate. The ice 
did not reach so far south on the hillside by an eighth of a mile or more as it did in the valleys situ- 
ated east and west of the hill. ‘This, perhaps, may prove that the ice over the hill dragged behind 
the deeper ice of the valleys because it there bulged somewhat above the general level of the surface, 


MON XXXIV 18 


274. GLACIAL GRAVELS OF MAINE. 


Waldoboro moraine. The phenomenon of crag and tail is very common 
in those parts, but I have discovered no lateral or medial moraines proper 
in any of the larger valleys, and I have crossed them all. The hills are 
not precipitous nor very steep, at least they do not prove so to the Maine 
farmer who has much of their surface under cultivation. These conditions 
make it improbable that any considerable amount of morainal matter got 
upon the ice by sliding from the hilltops at the time the hills were bare and 
glaciers still filled the valleys. 

The argument, then, stands thus: The moraine is not composed of pre- 
viously deposited till plowed up and pushed before it by the snout of the 
glacier. Neither can it contain much if any matter precipitated upon the 
ice from above. It is a fair inference that the moraine consists chiefly or 
wholly of matter which had previously got up ito the lower part of the 
ice from below. A part of it may have been on the surface of the ice at 
the time the moraine was bemg formed, but if so it was because it had been 
laid bare by the melting of the ice above it. The composition of the 
moraine proves that débris of all degrees of fineness, from the finest clay 
and dust up to the largest bowlders, were contained in the lower part of the 
ice. True, the moraine at the excavations near Winslows Mills is some- 
what more sandy than the average upper till of the locality, but this can be 
easily accounted for if we assume that it was deposited in the sea at the 
front of the ice, or became somewhat water washed by the terminal melting. 
Only a few of the stones of the moraine are distinctly scratched, in which 
respect they are like the stones of the upper part of the till. In a word, 
the material is the same as found in the upper portion of the till of that 
region. The structural difference consists in the fact that we have here 
piled in a single ridge material which during a gradual recession of the ice 
front would be scattered as a sheet over a zone a half mile, more or less, in 
breadth. 

MORAINES OF ANDROSCOGGIN GLACIER. 

The basal character of the drift is also seen at the terminal moraine of 
the local Androscoggin glacier. This glacier formed terminal moraines 
near the line between New Hampshire and Maine. Pl. XXV, B, shows 
the moraine on the north side of the river rising on the slopes of Hark Hill. 
If it carried surface moraines, the glacier ought to have deposited contem- 
poraneously with this moraine a lateral moraine comparable with it in size. 


U. S. GEOLOGICAL SURVEY MONOSRAPH XXXIV PL. XXV. 


aA. TERMINAL MORAINE; ON ROAD FROM WALDOBORO TO NORTH WALDOBORO, LOOKING EAST. 


Ice flow was from the left. 


FAI; 
Wid 


Ie 
iy 


B TERMINAL MORAINE OF LOCAL ANDROSCOGGIN GLACIER; GILEAD. 


ENGLACIAL DEBRIS. 275 


At various points on the hills that border the valley I found heaps of till 
of various shapes, but they have the forms of accumulations of englacial 
till, The only deposit having distinctly the form of a lateral moraine that 
I found in the valley is situated on the north side of the river and about a 
mile east of the Lead Mine bridge in Shelburne. This is one-third of a 
mile or less in length, and its origin is somewhat uncertain. he hills on 
each side rise often steeply to a height of 500 to 2,500 feet, and surtace 
moraines were as likely to form, in this valley as in any in New England 
except a few in the heart of the White Mountains. 

At all the other terminal moraines found in Maine the absence of 
lateral moraines emphasizes the conclusion that there was but little morainal 
matter borne on the surface of the ice that was derived, like the moraines 
of glaciers of the Alpine type, from avalanches and débris sliding from 
above onto the ice. 

Agassiz long ago reached the conclusion that the ice-sheet covered all 
the land, and hence the only way for morainal débris to get ito the ice 
was from below. The above-stated facts prove that late in the ice epoch, 
after the time when the higher hills began to rise above the ice, not much 
débris fell from above onto the ice, even in valleys bordered by steep hills. 
Up to the very last the drift was almost wholly basal. 


QUANTITY OF ENGLACIAL DEBRIS. 


The depth of the upper or englacial till does not necessarily give an 
estimate of the quantity of morainal matter contained in the ice at one 
time. If we conceive the ice-sheet suddenly divested of all motion, the 
scattered mass or sheet of englacial till left when the ice melted will repre- 
sent the amount of, débris in the ice at that time. But if the ice is in 
motion the case will be far different. Whenever the forward flow of the 
ice equals the terminal melting the ice front is stationary and a terminal 
moraine gathers as a frontal ridge. As the ice advances, the débris con- 
tained in a zone of ice perhaps a half mile or more in breadth is brought 
torward and dropped on the narrow moraine. In other words, the thickness 
of the moraine may represent the englacial matter not only of an area of 
ice equal to that of the moraine but many times this area. If now the 
melting comes to exceed the rate of advance, a series of parallel moraines 


276 GLACIAL GRAVELS OF MAINE. 


will be formed, and if the rate of recession is uniform, these successive 
moraines become confluent, as a sheet. 

This I conceive to be the best interpretation of the upper or englacial 
till. Only where the ice was stagnant does it represent the quantity of 
débris in the ice at the final melting, and only locally was it stagnant. 
Where the ice was in motion the thickness of englacial till may several or 
many times exceed the quantity of englacial matter, comparing equal areas 
of ice and land. 

There are numerous places where the rock is bare of till or the till is 
very thin. We here have proof that there were considerable areas of the 
ice that contained no glacial débris at the time of final melting. The inter- 
pretation of this fact is a matter of doubt. Many of the places bare of till 
are on the tops of hills that have deep sheets of subglacial till on their 
northern slopes. The situation suggests that possibly the ice had been 
robbed of its englacial material while passing up the northern slopes of the 
hills. We may here have a glimpse of a general scantiness of englacial 
matter when the ice had become thin and ready to disappear, or we may 
assume only local deficiency. 

The terminal moraines are from 10 up to 100 feet high. How many 
years’ accumulation they represent is now unknown. The least possible 
time we could allow is a single season, and an advance of the ice=0. This 
would give as the utmost admissible thickness of englacial matter 5 to 50 
feet. But if the ice was stationary, during the subsequent recession a sheet 
of the same thickness or thereabout ought to have been formed, and it was 
not so formed. This proves that the hypothesis of stationary ice is inad- 
missible. Structurally the moraines, at least those of Maine, can not be 
explained unless the ice was in motion. The retreatal moraines of the 
Muir glacier may possibly be a type of some of the moraines of the Andros- 
coggin glacier, but not of any others. The proof is irresistible that the 
moraines represent the débris of an area of ice much broader than their 
bases. The sheet of englacial till that covers most of the land is a more 
doubtful subject of interpretation. In a given place it may or may not 
represent terminal accumulations. 

Without venturing on very definite figures, and allowing for great local 
inequalities, I assume that the ice in Maine at a given place contained simul- 
taneously only a few feet of morainal matter, perhaps a maximum of 20 


GROUND MORAINE. BUT 


feet, and over most of the State very much less; in the slate regions often 
only a foot or two and from that down to 0. 


GROUND MORAINE. 


Excavations at the bases of the terminal moraines ought to exhibit well 
the differences between the englacial and the subglacial till. The moment 
we assume that the moraines were of englacial origin we are logically 
driven to look for a different origin for the lower layers of the till. For 
the matter of the moraines (englacial matter) shows little glaciation, while 
that of the lower part of the till is intensely glaciated. It is just what 
should be expected if it is a moraine profonde. Accumulations of it have 
a curved, flowmg outlie, quite unlike the heaps into which the englacial 
till was often thrown. These are the two fundamental arguments for the 
existence of a ground moraine. Hxpanded they are as follows: A moraine 
profonde consists of débris that has been between moving ice and the 
underlying rock. <A rock fragment can not be in such a situation without 
being subjected to great attrition against the rock or against other frag- 
ments if the ice preserves the known rigidity of ice under ordinary condi- 
tions It has often been assumed that under extremely great pressure ice 
becomes much more fluent or plastic than at ordinary pressures. If this be 
so, what bearing has the fact on the nature of the glaciation? 

Whatever theory of the origin of the lower or intensely glaciated till 
we adopt we must make it consistent with two facts: First, all the known 
excavations that penetrate to the bottom of the till reveal glaciated rock. 
Either, then, the whole mass of the lower till was rolled or dragged bodily 
beneath the ice, or each place overrun by the ice was first an area of erosion 
and subsequently one of deposition. Second, the depth of the rock scor- 
ings, their straightness and length, require a vast force to produce them. 
The immense amount of débris that has been fractured or ground to rock 
flour or scratched and polished is the ample counterpart of the very great 
abrasion of the rock. No theories of the superior fluidity of ice under 
enormous pressures or under any other conditions can be allowed to obscure 
the fact that at the time the rocks were scored the stones that did the work 
“were moving under great pressures and with wonderful steadiness of move- 
ment. ‘The increase in plasticity, if such there was, was not sufficient to 
impair seriously the rigidity of the ice. If the stones that were ground 


278 GLACIAL GRAVELS OF MAINE. 


against the solid rock were held embedded in the ice, it was solid enough 
to deserve the name of ice. If they were rolled or dragged beneath it, 
only solid ice could furnish the necessary friction. No matter what theories 
we indulge as to basal melting or semifluidity under sufficient pressure, or 
as to the conditions prevailing at any given point when it was a place of 
deposition of stationary ground moraine, we must admit that over the area 
of erosion at any period in the history of the ice-sheet there was a body of ice 
beneath which, under the enormous pressure extended, terranes were 
turned to dust. The marks of this tremendous conflict are conspicuously 
shown by the lower till and not by the upper. Plainly they are what 
should be expected of material that has been beneath the ice. 

Again, the deeper accumulations, such as the drumlins and the sublen- 
ticular sheets on the hillsides, have a rounded outline. Under the action of 
water waves a sand or gravel bar assumes the form most favorable to its 
stability, and a mass of débris ought to assume a corresponding form while 
ice flowed over it. The drumlins often show beautiful curves and billows, 
and the type of ground-moraine scenery is very different from that of 
moraines either of surface or englacial débris. The latter show more variety 
of form and gradient of slope and have a more or less heaped appearance. 

It is perhaps now impossible for us to form an accurate picture of the 
relations of the englacial and subglacial morainal matter to each other and 
to the subjacent rock. We know that the englacial till is but little glaciated, 
and hence must have entered the ice before being rolled or dragged between 
the ice and the rock. We do not know in detail the manner of its entrance 
into the ice, though that must have occurred soon after the flow was 
established, or possibly even before the flow of consolidated ice began. 
We do not know the relation of this assumption of englacial matter to the 
history of the adjacent regions. We do not know certainly whether the 
stones and particles of the ground moraine were from the first and con- 
stantly beneath the ice, or whether each particle was at one time within the 
ice and was subsequently torn from its grasp, or whether both kinds of 
matter are now a part of the subglacial till, though there is a strong proba- 
bility that the last-stated hypothesis is the true one. How much of the 
ground moraine was stationary during the time of the accumulation? We 
do not know the height in the ice attained by the englacial débris, nor its 
vertical and horizontal distribution. In a general way we know that it got 


GROUND MORAINE. 279 


into the ice before it had been much overridden and glaciated; that the 
region of chief deposition of the subglacial till was near the front of the 
ice-sheet, where the ice was thinner; that back of this region there was 
another zone, perhaps found not very far below the distal margin of the 
névé, where pressure and velocity of motion united to produce great ero- 
sion of the rock and transportation of subglacial débris, while under the 
névé transportation was less active, whether because of the depth, or the 
structural condition of the snow and ice, or other causes, is unknown. But 
while the details are thus uncertain, the fact of the existence of the ground 
moraine is satisfactorily established. 

In the foregoing discussion it has been assumed that the ground moraine 
was wholly formed between the ice and the rock, and that the flowing out- 
lines of accumulations were carved by the ice flowing over them. There 
is a possible alternative theory that perhaps ought to be noticed. No mat- 
ter whether we consider the flow of the ice as plastic or viscous, we can 
conceive of a mass whose internal friction is so great—forming, as it were, a 
mass of till mfiltrated with films and threads of ice—that it could remain 
embayed while the purer ice flowed over or around it. Such an embayed 
mass (half-till, half-ice) would be carved into the lenticular form as the 
glacier flowed over it, just as if it were a mass of true subglacial moraine. 

In reply to this it may be said that if débris scattered through the 
lower part of the ice were reached by heat rays from the sun or other 
source of heat external to itself it would absorb the heat and, by melting 
the ice in contact with it, might increase the fluency (or plasticity) even 
more than the friction of the stones diminished it. Certain bowlders in the 
Alps have been supposed to rise upward in the ice in consequence of the 
absorption of solar heat by their upper surfaces." The stances where thin 
glaciers have been observed to flow over bowlders without pushing them 


1Tt has been contended that rocks warmed from above naturally rise in the ice. This is doubt- 
ful as a general proposition. The ice melts with contraction of volume, leaving a small cavity above 
the water. Molecular heat could then no longer produce melting except where the ice was in contact 
with the water. The upward melting could proceed from radiant heat alone, while the radiant molec- 
ular heat communicated to the water would be largely transferred to the bottom of the cavity, the 
water of 39° seeking the bottom. Whether as a net result the melting would be most rapid upward 
or downward would depend on the size of the fragments, their shape, etc. If it be contended that 
the ice from beneath would push the stone upward fast enough to fill the cavity of melting, we must 
demand the proof of such action against the force of gravity. This note applies only to the supposed 
rising of débris in the ice owing to heat from above. Whether vertical ice movements could raise the 
débris is a very different question. 


280 GLACIAL GRAVELS OF MAINE. 


forward (Niles! and Spencer’), also over sand and gravel without disturb- 
ing the stratification (Chamberlin®), may be due in part to radiant heat 
absorbed by the bowlders or communicated directly to the ice. It is uncez- 
tain to what depth solar heat penetrates the ice, yet during the decay of 
the ice-sheet a time must have come when the sun could penetrate the thin 
ice to the moraine stuff scattered through it. 

In attempting to sum up this controversy I find too much hypothesis 
and too little fact. It is important to study in the field, if possible, the 
effect of a large amount of englacial matter on the rate of flow. In the 
present state of the case it must be considered doubtful if any large accu- 
mulations of till have been made in this way. If there were such masses 
of ice embayed because of the contained till, the till would be upper rather 
than lower till, or at least a transition between them. The matter of the 
lenticular hills has been thoroughly glaciated, and it remains to be proved 
that the mutual friction of till fragments in a mass of partially stagnant 
ice could simulate the greater attrition which must inevitably mark those 
which have been ground against the solid rock or against each other at the 
bottem of the ice. 

Some other questions demand attention. 


DRUMLINS. 


1. Were the drumlins accumulated at the ice front during the retreat 
of the ice at unequal rates, so that they are a form of terminal moraine? 
It can be confidently answered that their shapes and materials are wholly 
unlike those of the terminal moraines of Maine. 

2. During the final melting of the ice the surface would melt un- 
equally, since the larger bowlders and deeper masses of till would par- 
tially protect the ice beneath them from melting. There would be much 
lateral sliding of till into the depressions thus formed on the surface, as 
seen by Prof. G. F. Wright on the Muir glacier of Alaska, and this process 
would originate trains of bowlders, and ridges and mounds of various 


1 Upon the relative agency of glaciers and subglacial streams in the erosion of valleys, Am. Jour. 
Sci., 3d series, vol. 16, pp. 366-370, 1878. 

2Notes on the erosive power of glaciers as seen in Norway, Geol. Mag., new ser., Dec. III, vol. 
4, pp. 167-173, 1887. 

3Qbservations on the recent glacial drift of the Alps, Trans. Wisconsin Acad. Sci., Arts, and 
Letters, vol. 5, pp. 258-270, 1877-81. 


ae 


DRUMLINS. 281 


shapes, and they would be composed of upper till, not the intensely gla- 
ciated lower till, unless first eroded and then rebuilt by the glacier. It is 
difficult to conceive how smoothly rounded hills in such large numbers and 
of such great size could result from this process. Moreover, some of the 
masses of thoroughly glaciated matter are long ridges parallel with the 
glaciation. These are still more difficult of explanation as being due to 
accumulations in surface hollows of the ice. Osars or sandy ridges would 
result, not masses of till containing much rock flour. 

3. Are the deep masses of till remains of a former sheet of till of 
which the greater part has been eroded by the sea waves, as suggested by 
Prof. N.S. Shaler?* This can not have been the case in Maine, for the 
following reasons: 

First. These deep masses of till are sometimes 1 mile or more from 
any other similar mass. The amount of erosion required is enormous. 

Second. The presence of continuous beaches from high level down to 
the sea, shown on Monhegan Island and other exposed coasts, proves that 
if great masses of till had been eroded most of the larger stones would 
now remain as broad sheets in the valleys or as terraces on the hillsides. 
On the other hand, the beach gravels of Maine are relatively scanty and 
bear no relation to the positions of the drumlins. 

Third. The coast region, where the lenticular hills are most numerous, 
is largely covered by marine sands and clays. If the till was eroded in the 
manner supposed, the erosion must have occurred before the deposition of 
these marine beds. These beds would preserve the beach gravels beneath 
them from erosion. No such rolled gravels now exist beneath the clays. 

Fourth. If we suppose that there has been such an erosion of the till, 
we must account for the fact that the kames and marine deltas deposited in 
the sea by the glacial rivers have escaped in such good state of preservation. 

Fifth. The lenticular sheets of till on the northern slopes of hills must 
have substantially the same origin as the drumlins themselves. They lie 
inclined against the hills and reach upward on the slopes for several 
hundred feet. The erosion required to carve away the surrounding por- 
tions of a former deep sheet of till to such great heights must certainly have 
left its mark. Yet there are multitudes of these hillside lenses in regions 


‘THlustrations of the earth’s surface: Glaciers, by Shaler and Davis, p. 63, Boston, James R. 
Osgood & Co., 1881, 4°. 


282 GLACIAL GRAVELS OF MAINE. 


where all the vigilance of road overseers and selectmen exercised for years 
has not succeeded in finding a wagon load of genuine water-washed gravel. 

4. Are the drumlins remains of a former sheet of till irregularly eroded 
by the glacier? I do not know how a glacier can deposit till and not at 
the same time also deposit glacial gravel. Glacial streams are inseparable 
from a glacier. The work of the latest ice-sheet is a fair sample of what 
former ice-sheets did, differmg only as they have differed in size or time of 
continuance. Now the latest Ice period has left hundreds of square miles 
covered with well-rounded stones and bowlders distributed over a large 
part of this State, as well as of New England generally. If at any future 
time Maine is again glaciated, those rounded stones will be meorporated in 
the till or pushed bodily out into the Gulf of Maine, bemg more or less 
changed in shape during the process, but still being quite different in form 
from angular stones of fracture. It is possible to conceive of glaciation so 
severe as to remove all the glacial gravels from Maine into the sea, but 
farther west, where the outer terminal moraines are deposited on the land, 
the water-rounded stones of the last ice-sheet would appear in the moraines. 
If any one claims that the lenticular hills are remains of the till of a former 
Ice period that failed to be eroded by the latest invasion of the ice, on 
him rests the burden of proving that the till and terminal moraines of 
southern New England contain a sufficient number of once rounded stones 
and bowlders to account for the glacial gravels of such supposed more 
ancient ice-sheet and which the later ice incorporated into its own deposits. 
Of course it is assumed that if a sheet of till can be eroded by ice, masses 
of sediments would sooner be eroded. For the present the theory under 
examination can not be insisted on. 


RELATION TO MARINE GRAVELS. 


The relation of the lower till to the beach gravel deserves notice in 
this connection. 

A good place for study of the subject is at Matinicus Island. A 
lenticular mass of till 10 to 50 feet deep covers the western portion of the 
island, as is proved by the cliff of erosion at the present beach and by 
wells. The till is everywhere covered by a few feet of beach gravel. The 
till is very fine in composition, is very compact and intensely glaciated, has 
a dark-blue color, and is typical lower till, very different from the matter of 


RELATION OF LOWER TILL TO MARINE GRAVELS. 283 


the Waldoboro moraine. At the time the sea stood at its highest level the 
water would be about 150 feet deep over the top of the island. Here then 
is a good place to observe the effect of the sea waves on the ice and its 
contained till as the ice front retreated northward. If this lenticular mass 
of till was contained in an embayed mass of ice rendered viscous by the 
amount of solid matter distributed through it, or if it was cast out at the 
ice front as any kind of frontal moraine, then we ought to find the till more 
or less assorted by water unless the ice had melted with extraordinary 
quietness before the elevation of the sea. A multitude of facts furnished 
both by the terminal moraines and by the deltas deposited by glacial rivers 
in the sea, as well as by the valley drift of the river valleys, point to the 
conclusion that the sea stood at high level during all the later part of 
glacial time. On Munjoy Hill, Portland, are a number of small irreeular 
masses of sand, filling pockets in the clayey till. They are found only near 
the surface. In the lower part of the deep masses of till I have found no 
water-classified matter. The presence of signs of water, either glacial 
streams or marine waves, in the upper portion of the till only makes their 
absence in the lower till still more suggestive. 

The relations of the beach gravels to the deep masses of till are not 
only perfectly consistent with the subglacial origin of the lower till, but 
distinctly favor this hypothesis. 

On the whole, we may affirm that whether we regard the composition 
of the lowest portion of till, or its relations to the terminal moraines or to 
the glacial gravels on the marine deposits, all find their simplest explanation 
in the hypothesis of a ground moraine. 

It is not asserted that a ground moraine covered all of Maine. It is 
well known that many places are bare of till where there has been no 
erosion by the sea or streams. There are places where probably only sub- 
glacial till is present, and others where the till was all englacial, or nearly 
so. Neither is the line of demarcation between these two deposits always 
sharply defined. Indeed, they graduate one into the other so as often to 
render it difficult to make out the line of separation. Probably the lower 
the point in the ice where morainal fragments occurred, the more glaciated 
they would be—a sufficient cause of gradations in glaciation between the 
upper and the lower til. 


284 GLACIAL GRAVELS OF MAINE. 


BOWLDER FIELDS AND TRAINS. 


Many details as to the till are here omitted, as not bearing on the sub- 
ject of the glacial gravels. One phenomenon must, however, be noted— 
the bowlder fields. In a certain sense the whole of the granitic regions 
might be considered as bowlder fields. But the fields referred to are dif- 
ferent. They lie in regions of coarse slates. The whole surface is so cov- 
ered by slabs, up to 6 or 8 feet long, that one can travel a half mile by 
stepping from bowlder to bowlder. The only soil is found 2 to 5 feet below 
the surface. The babbling of invisible streams is heard as they make their 
way among the bowlders. Raspberry bushes peer up through the rifts 
between them. One of these bowlder fields is found about a mile south of 
Tomah station of the Maine Central Railroad. This is situated near the 
junction of two large glacial rivers, and the finer parts of the till may have 
been washed away by the waters. I observed a still larger bowlder field 
in T. 7, R. 4, Aroostook County. It is situated 2 miles from any known 
osar, and its cause is obscure. 

In the wilderness between Aurora and Deblois a train of huge granite 
bowlders, which is parallel with the glacial scratches of the region, is inter- 
sected obliquely by the Katahdin osar. The bowlders are piled one above 
another so as to form a ridge, and some of them overlie the gravel. The 
bowlder trains bear a relation to outcrops of granite rocks, but are not lateral 
to valleys. The appearances indicate that they were not medial or lateral 
surface moraines, but either distinctly subglacial or stranded basal matter, 
so that in their ridge-like development they are drumlins of coarser material 
than the ordinary. 


WAS THERE MORE THAN ONE GLACIATION OF MAINE? 


The observations of White, Winchell, Upham, Chamberlin, Salisbury, 
McGee, and others in the Upper Mississippi Valley prove that there were at 
least two principal advances of the ice, separated by a rather long interval. 
It has since been a special object of search to Eastern geologists to find 
similar advances in the Northeast. At one time it appeared probable that 
I had found traces of two tills that might belong to different periods. The 
dam of the Penobscot River where it flows out of South Twin Lake had 
broken a short time before my visit to the place. The water had escaped 


WAS THERE AN INTERGLACIAL PERIOD IN MAINE? 285 


around the end of the wooden part of the dam and eroded a channel in the 
earth, thus affording a fresh section down to the solid rock. At the bottom 
were several feet of a hard, tough, clayey till that resisted erosion wonder- 
fully and broke up into blocks 2 to 3 feet in diameter. 

Above this was a lighter-colored and less compact till forming a north- 
and-south ridge or elongated drumlin. The material was indistinctly 
arranged in layers, yet was not an osar composed of water-transported 
matter, but was true unmodified till, The great contrast between the tough 
under stratum and the more siliceous overlying layer made me suspect that 
here were the ground moraines of two different ice-sheets. Subsequent 
observations in many parts of the State have convinced me that this phe- 
nomenon, which is a very common one, is probably due to the overlap of 
till derived from two different kinds of rock. Thus at South Twin Lake 
the local rocks are slates and other fine-grained schists. The lowest (blue) 
stratum of the till is derived from the local rocks, while the overlying ridge 
(also a part of the ground moraine) is composed of matter transported from 
the granitic region about Mount Katahdin, situated not far to the north. 
This overlapping of till having different characters is found wherever the 
ice passed from one kind of rock into an area of another kind. We do 
not need to postulate two glacial periods in order to account for it, although 
that is certainly possible. It is just what should be expected in the case of 
an ice-sheet moving over areas of different kinds of rock, provided the 
eround moraine was not all formed simultaneously, but each region was first 
an area of denudation and subsequently of accumulation. During the 
first period of denudation the scratching was produced. The first of the 
embayed ground moraine would be composed chiefly of local matter, which 
would subsequently be overlain with far-traveled matter. 

All parts of the State have been examined without finding peats or soils 
within the till, or anything indicating an interglacial period in Maine. 

The relation of the marine clays to the till deserves special study. I 
could find no fresh exposures showing the relations of the Waldoboro 
moraine to the marine clay. On the surface the clay overlay the moraine, 
but the base was not seen. At Sabatis Village the marine clays also over- 
lay the terminal moraine, to a depth of 8 feet, but the base of the moraine 
was not exposed. It is thus uncertain whether at the base the terminal 
moraines cover the marine clays or not. 


286 : GLACIAL GRAVELS OF MAINE. 


Since 1861 Prof. C. H. Hitchcock has repeatedly expressed the belief 
that two advances of the ice are provea by the relations of the upper till 
to the fossiliferous marine clays at Portland.’ The same opinion has been 
expressed in the geological reports of New Hampshire. Professor Hitch- 
cock’s latest conclusions are contained in his report as a member of the 
American Committee of the International Congress of Geologists:” 


* * * Very clear evidence of the relations of the fossiliferous beds to both tills 
is found at Portland, Maine. Here clays and sands rise about 100 feet above the sea 
and hold 121 species of organisms, all of living forms. They rest upon typical lower 
till, and are overlain by as much as 50 feet thickness of upper til. At the time the 
reporter described these facts the prevalent doctrine of the triple nature of the glacial 
period had not been established; but it seems clear that two seasous of ice presence 
are indicated at this lecality. * * * 

The meaning of the terms ‘‘interglacial,” as well as ‘upper” and 
“lower” till, must be made definite when used in this connection. The use 
of the term interglacial as of world-wide application can not be warranted 
until the facts are all in; for the present it can only be admitted to express 
the facts im particular regions explored, e. g., the Mississippi Valley, large 
parts of Europe, ete. At the great terminal moraines there may have been 
many advances and retreats of the ice, and one studying the till there 
might come to the conclusion that there had been many glacial and inter- 
glacial periods, and so there would have been at his place of study and 
from his standpoint; yet all these advances of the ice might be comprised 
within what another would consider as a single invasion of the ice, mere 
minor accidents of a larger movement. So, too, the term ‘‘upper” till may 
mean englacial till, or, where there are tills deposited during two distinct 
advances of the ice separated by a warmer climate, it may mean the later 
of these tills The use of the term by Professor Hitchcock in connection 
with the reference to the triple nature of the Glacial period seems to indi- 
cate that he considers the two seasons of ice presence at Portland as the 
correlative of the two glacial epochs of the interior. 

Let us review the points brought out by Professor Hitchcock: 

1. The locality cited is situated at the western end of Portland, where 
there have been extensive landslips, and it is difficult to determine what was 
the original order of deposition. The proof of so important an event as an 


1 Thus, in the Preliminary Report upon the Natural History and Geology of the State of Maine, 
1861, p. 275: ‘‘We have recently noticed that in Portland these clays underlie a coarse deposit, which 
has always been referred to the unmoditied drift,” ete. 

2Am. Geol., vol. 2, p. 302. 


WAS THERE AN INTERGLACIAL PERIOD IN MAINE? 287 


- interglacial period ought to rest in observations made in more places than 
one, and in places where there can be no suspicion of landslips. 

2. I have examined the place since reading Professor Hitchcock’s pub- 
lications, also after he has kindly written me descriptions. Near the same — 
locality Dr. William Wood and Mr. C. B. Fuller, of the Portland Society 
of Natural History, have recently exhumed a skeleton of a walrus in sandy 
clays. I hpve examined several excavations in that vicinity (all that are 
now open), and can not be sure that I have seen the exposures referred to 
by Professor Hitchcock. I have found masses of rounded cobbles and 
bowlderets overlying the fossiliferous marine beds, also small masses of 
more till-like’ appearance. Both were in material that had slipped down 
from the hill above; but not to insist on this, let it be assumed that both 
kinds of deposit can there be found overlying the marine beds in situ. 

If the “upper till” referred to by Professor Hitchcock is composed of 
the rounded gravel and bowlderets, we have a case here of transportation 
by water as well as by ice. The great glacial river which reached from 
the upper Androscoggin Lakes to Portland could transport bowlderets 

_ beyond the front of the ice into the sea, especially in the‘time of summer 
floods. It is a possible interpretation that the ice was confronting the sea, 
and if so it might often happen that matter brought down by glacial rivers 
would be dropped on marine beds previously laid down. The presence of 
such water-rounded matter is not of itself a proof of a readvance of the 
ice over the fossiliferous clays. 

But if this “‘upper till” was transported not by water, but by ice, we 
have at Portland substantially the same problem as the supposed one at 
the Waldoboro moraine overlying the marine clay. The problem is to 
determine whether here are two presences of the ice such as warrant the 
correlation of the Maine deposits with those of the Interior. 

3. During the latest glacial period in the Northwest there were depos- 
ited the great kettle moraine and broad sheets of morainal drift (up to a 
breadth of several hundred miles), varying in depth up to 400 or 500 feet 
or more. The amount of till overlymg a supposed interglacial clay at 
Portland, and perhaps at Waldoboro, is inconsiderable compared with the 
ereat sheets and moraines of the Northwest. We can not correlate them 
unless it can be proved that in Maine the ice carried less morainal matter, 
so that smaller moraines represent a greater relative time of deposition. 


288 GLACIAL GRAVELS OF MAINE. 


A. The glaciation of the country south of the Waldoboro moraine 
differs in no respect that I can discover from that of the country north of 
it, and the same is true of Portland. ‘There is no sign of the subaerial 
erosion that would result if the ice only advanced to these places after a 
retreat at all comparable in time to the interglacial epoch of the West, sup- 
posing the land to have been above the sea. On the other hand, if it was 
beneath the sea during all or even a part of the imterglacial, period, we 
ought to find a different development of the marine beds south of those 
places (the supposed line of ice front durmg the second advance of the ice) 
from that north of this line. I do not recognize any difference except the 
general change we discover everywhere as we go to greater elevations up 
to 230 feet. 

5. If the supposed readvance of the ice at Portland over marine beds 
is correlative to the second glacial advance over the Northwest, we ought 
to find everywhere along the coast a series of terminal moraines or morainal 
sheets overlying the marine beds. Only a few places have been found 
where this can be admitted as even remotely probable. The few scattered 
bowlders in the marine clays can better be accounted for as due to ice floes 
and small bergs. 

6. Existing glaciers are known to advance and retreat alternately, or 
for a time remain stationary 


7 


Analogy requires us to postulate similar 
behavior of the great ice-sheet. It is not necessary to correlate the time of 
such temporary halts of the extremity of the ice, or of its readvances, with 
the interglacial period of the Northwest. They may have been only for a 
few vears at most; not a geological epoch. ‘The small terminal moraines 
and supposed readvances of the ice in Maine correspond generically to the 
smaller retreatal moraines of southern New England and the Northwest. 
At the time of their formation the doom of the last ice-sheet had been pro- 
nounced. The algebraic sum of the secular accumulation and waste of ice 
had the minus sign, though particular elements might be plus. 

7. It is granted that a thin body of ice might advance over marine 
sediments without eroding them, just as happened with the soils of the 
Upper Mississippi Valley. But if the flow were to continue long enough to 
equal the second advance of ice over the Northwest, a considerable body 
of till, both subglacial and englacial, ought to be left overlying the clays. 
The finding of only small masses of till or a thin sheet of scattered bowl- 


WAS THERE AN INTERGLACIAL PERIOD IN MAINE? 289 


ders may mark an advance of thin ice, but only a temporary one. If there 
shall be found in Maine unmistakable subglacial till im situ overlying the 
marine clays, it will indicate a much longer period of advance than any 
interpretation now allowable. 

8. If the sea rose while the ice still remained, so that the waves beat 
upon a shore of ice, pieces of ice would from time to time be detached, 
partly as floating bergs, but in case of ice containing englacial matter it 
might often happen that the pieces would not float because of the morainal 
matter contained, and when the ice melted such fragments would form a 
deposit similar to true glacial-transported till. Such might often be lodged 
in the marine beds or glacial gravels. I have not sufficient facts to discuss 
the hypothesis at present, yet this question must be considered before the 
significance of small till masses on or in marine sediments can be regarded 
as definitely determined. 

The floating bergs would naturally drop fragments upon the sea bot- 
tom, and perhaps sometimes quite deep masses. These deposits must be 
distinguished from matter brought to the place of deposition by glacier ice. 

9. It is agreed that the fossiliferous sands and clays of Portland overlie 
a fine blue clayey till, apparently subglacial. But on the upper slopes of 
the hills I found fossiliferous sand overlying glacial gravel. This I regard 
as beach sand and gravel, composed of the material washed down from the 
top of the hill by the waves of the sea. Glacial sand and gravel were 
originally deposited on the tops of the hills. Part of this deposit and per- 
haps some till were subsequently eroded by the sea and strewn on the hill- 
sides. The alternative hypothesis would be that the fossils grew in the 
sediments of the glacial streams as they were poured out from ice channels 
into the sea. 

10. In determining whether in a given region there have been two ice 
periods, we have to compare the shapes of the stones of the till of the 
supposed two ages. As elsewhere noted, a system of glacial streams is 
inseparable from a glacier, and these waters leave a system of glacial sedi- 
ments. If ice subsequently advanced, the rounded stones of this glacial 
gravel would either be overridden by the later glacier or be partly or 
wholly eroded and pushed forward by it, and in either case they would be 
found in either the earlier or later till, perhaps at the terminal moraines. 


They might be somewhat planed or modified in shape in the process, yet 
MON XXXIV——19 


290 GLACIAL GRAVELS OF MAINE. 


where there were large numbers of them they could hardly fail to betray 
the fact that they were once rounded by water movements and were not 
fragments of fracture and cleavage. In Maine there are places near the 
White Mountains where I found till containing numerous water-rolled 
stones, but in general such matter is very small in amount as compared 
with what was once angular gravel or talus matter. I find in the till no 
adequate representation of the water-rounded stones of a more ancient 
glacier. In the terminal moraine near Waldoboro there are few it any 
such; none were observed. 

11. The Waldoboro terminal moraine is 6 miles long, and is much 
larger than anything of the kind at Portland. So far as I have yet discov- 
ered, it does not prove a readvance of the ice, but can equally well be 
assumed to have been formed at the ice front during a pause in the retreat. 
There is still stronger reason for this conclusion in the case of the Portland 
deposits; yet if it shall be hereafter proved that there was an advance of 
the ice immediately preceding the time of the formation of this moraine, 
we still have the small size of these deposits to account for before corre- 
lating them with the great kettle moraine, or with a retreat and readvance 
of the ice for hundreds of miles, such as took place in the Northwest. 

Summary— Two lines of reasoning point toward two possible glaciations 
of Maine. The first is based upon the finding of two different layers of 
the till, possibly the till of two different ice periods. No sedimentary or 
fossiliferous beds have been found between them, and a better imterpreta- 
tion is that they are derived from two different kinds of rock—one local, the 
other from a distance. The second refers to the finding of till or glacial 
gravel overlying fossiliferous marine beds. It is certain that the marine 
beds in Maine overlie a stratum of till most or all of which was subglacial. 
They therefore were deposited late in the Ice period of that coast, when the 
ice had receded far back from its extreme limit. Waiving all doubts as to 
the Portland beds having been caused by landslips, and assuming the most 
favorable construction, i. e., that there are terminal moraines and other 
glacial deposits overlying marine sediments, we must consider the signifi- 
cance of this assumed fact. My interpretation of the facts is that there is 
no proof that these supposed advances of the ice were for any but very 
limited times and distances, as is proved by the small size of the deposits 
and the fact that the glaciation and development of the marme beds vary 


GLACIAL SEDIMENTS. 291 


but little when we study them north and south of these moraines. Local 
advances and retreats of the ice might be expected during the decay of 
the ice-sheet, but they are to be regarded as minor incidents of one 
Glacial period rather than distinct periods worthy of a place in geological 
chronology. The moraines that correspond to the outer terminal moraines 
of the second ice-sheet of the Northwest are to be sought for in the 
Gulf of Maine, not along the present coast. The so-called interglacial 
period of the Northwest was longer than the intervals between the retreats 
and readvances of the ice in Maine, so far as the known facts warrant 
conclusions. . 

The significance and explanation of the fact, if such it be, that there 
was but one glaciation are left for future investigation. 


GLACIAL SEDIMENTS. 


Under the term ‘“‘till,” as here used, is included all matter transported 
to its present position by glacier ice. The term “glacial sediments” denotes 
all matter transported to its present position by streams of water from the 
melting ice. No doubt ice movements contributed to the transportation of 
kame matter. Yet clearly we have in case of the glacial sediments a form 
of transportation that the till did not undergo. While the till is glacier 
drift simply, the former are glacial drift plus water drift. 


RELATION OF WATER TO THE GLACIER. 


Energy reaches the glacier in various forms. Radiant energy comes 
to it from the sun and other bodies. Part is reflected, part is radiated and 
lost, and part is absorbed, which is but another way of saying that it is 
transmuted into molecular motion and is expended in doing work within 
the ice, such as melting it, raising its temperature, or aiding its flow. 
Molecular heat is communicated to the ice from surrounding bodies and 
performs the same kinds of work as radiant.energy. Most of the radiant 
heat comes from the sun, most of the molecular heat from the air and the 
summer rains or from the earth beneath the ice. The chief sources of heat 
act from above, and there the most of the melting and other direct action 
of heat takes place. The glacier is one form of heat engine. From the 
time that heat aids in cementing the separate snow crystals into clear blue 
ice up to the time that it resolves the ice back again into granules and 


292 GLACIAL GRAVELS OF MAINE. 


erystals and melts them, heat is inseparably connected with all the work of 
the glacier. Water is the heat transport of this heat engine. The waters 
derived from the melting ice flow along the surface or gather in pools until 
they find a crevasse down which they can escape. In passing from the 
surface to the bottom of the ice they carry heat with them. The phe- 
nomena of both subglacial and superglacial streams are largely determined 
by the behavior of water with respect to radiant and molecular heat. The 
most important of these relations are the following: 

1. Water is a poor conductor of molecular heat, but a good absorber 
of radiant energy. 

2. Water, like all fluids, readily transmits and distributes molecular 
heat by means of the convection currents so easily set in motion within it. 

3. The temperature of water at its greatest density is 39.1° F. 

4. The temperature both of melting ice and of freezing water (under 
ordinary conditions) is 32° F. 

5. The specific heat of water is very great. 

As a result of these properties of water, we have water above and 
below the ice, and perhaps in some cases distributed everywhere through 
it The glacial streams erode their banks and walls in a manner peculiarly 
theirown. Water is employed in the hydration of the clay which is formed 
beneath the glacier. Glaciers have their drainage systems as truly as does 
the land, and no other form of stream erosion is so complex. Ii a word, 
we can not conceive of a glacier without its system of waters. The glacial 
sediments are as important a matter of investigation as glaciated stones 
themselves, if we are to detect former glacial periods. 


SIZES OF THE GLACIAL RIVERS OF MAINE. 


Many considerations prove that the precipitation over a large part of 
North America was very great during glacial times. ‘The occurrence of 
Lakes Bonneville and Lahontan in the Great Basin and the observations 
of Professor Whitney in California unite with the facts as observed in many 
other parts of the country to establish the general conclusion. 

Mr. Walter Wells, in his report on the water power of Maine,’ pointed 
out many circumstances favorable to a large average precipitation in the 


1 Provisional Report upon the Water Power of Maine, by Walter Wells, Secretary of the Hydro- 
graphic Survey, Augusta, 327 pp., 1868, 8°. 


SIZES OF GLACIAL BIVERS. 298 


State He computed the annual discharge of the present rivers of Maine 
at 1,229,200,000,000 cubic feet, or 3,368,000,000 cubic feet daily. This 
represents a precipitation of about 33 feet per annum. 

Obviously in glacial times that portion of Maine which was within the 
area of accumulation or névé had less water discharge than the precipita- 
tion, the surplus being pushed forward as flowing ice into the zone of melt- 
ing. The position of the névé line would determine the ratio, at any given 
time, of water discharge to the total precipitation over the area now under 
consideration. The location of the néyé line during the time of thickest ice 
is uncertain. The glaciation of the islands off the coast proves that at one 
time the ice advanced out into the Gulf of Maine. Later, at a time when 
the ice had retreated before the rising sea nearly or quite to its coast, great 
glacial rivers were pouring into the sea and were depositing in open tide 
water the largest marine deltas in the State. Here and there we find marine 
deltas south of this line, proving that the glacial rivers had previously to 
this ‘time been pouring into the sea at various points in the course of the 
retreat of the ice. At the time the ice front had receded as far north as 
the present coast line the whole coast region of Maine to a breadth of 100 
miles must have been in the zone of wastage, and either at this time or 
later the whole State was in this zone. 

The melting of the great body of ice that covered the land and was 
continually renewed by flow from the north would of itself give a large 
melting-water discharge over the zone of wastage. To this must be added 
the precipitation over the zone itself. During part, perhaps all, of the 
period after the ice had retreated to the present coast line, the land stood at 
less elevation in Maine than at present. This would tend to lessen the pre- 
cipitation, but only in small degree. On the other hand, during a part, at 
least, of this period the sea advanced so far up the St. Lawrence and Cham- 
plain valleys that New England was a peninsula or island unusually 
accessible to moisture from the ocean. 

Whether we look, then, at the great quantity of the glacial gravels, or 
at the large size of the stones and bowlders transported, or at the broad 
plains of valley drift which were often deposited while ice still lgered to 
the northward, or at the local geographical conditions, or at the climate 
prevailing at or about this time in various parts of the country, we find that 
everywhere the field phenomena require a large supply of water. The 


294 GLACIAL GRAVELS OF MAINE. 


precipitation here near the sea must have been large, even if diminished 
from what it had been during the time of maximum glaciation. 

For these and other reasons we postulate a larger water discharge in 
Maine in late glacial times than the present. The glacial rivers exceeded 
the present rivers in number and had correspondingly smaller drainage 
basins. This tended to diminish the size of the individual rivers, yet some 
of them have left level plains one-eighth to one-half mile wide, and appear 
to have equaled or surpassed the discharge of the larger rivers of the present 


time. 
ZONES OF THE MAINE ICE-SHEET. 


According to the accounts of the explorers named above, the interior 
of Greenland is covered with snow fields. At the highest elevations if there 
is any melting it is limited, since Nordenskjold’s Laps found the surface dry 
and powdery. At lower elevations the melting becomes more abundant 
and the surface waters slowly ooze through a zone of slush.. Then we find 
pits filled with water, and, by degrees, the waters uniting to form surface 
streams. Some of these have been traced for several miles and are from 
4 to 10 feet wide. Still descending, we find crevasses appearing, sometimes 
near the nunataks, at other times where none are visible but where the ice 
is probably flowing over a buried ridge. Into the crevasses the surface 
streams pour and disappear, escaping as subglacial or englacial streams. 
Sometimes they pour with a loud roar into small lakes within the ice. 
Some of the crevasses are very wide as well as deep, one observed by 
Lieutenant Peary being 50 feet wide. As we approach the outer margin 
the surface becomes indescribably rough with blocks, hammocks, and ridges. 
Here the water derived from surface melting need flow only a few feet or 
rods befo.e plunging into the depths. 

These observations give us a general conception of an ice-sheet with 
respect to its waters of surface melting. Over all the region broken by 
crevasses we have an elaborate system of subglacial and englacial streams 
which receive the waters of the short surface streamlets. Above this zone 
is another, of superficial streams, then the area where the snow absorbs all 
the water of surface melting, which becomes progressively less as we go 
upward. 

Applying these principles to Maine, we note that the average slope of 
the land southward is only from 3 to 10 feet per mile, much less than is 


ZONES OF THE MAINE ICE-SHEET. 295 


found in much of Greenland. This would favor a low surface gradient of 
the ice-sheet. The slope being southward would favor a higher gradient. 
It is probable that on a uniform slope the gradient is chiefly determined by 
the ratio between snow precipitation and waste. During the advance and 
retreat of an ice-sheet over transverse hills and valleys the surface gradient 
must often change with some corresponding change. in the positions of the 
crevasses and in the boundaries of the zones of superficial and subglacial 
waters. . 

The ice flowed over Mount Desert Island to an unknown depth.. From 
there to Mount Katahdin the distance is approximately 110 miles, and they 
are nearly in the same lines of glacial motion. Prof. C. H. Hitchcock, in 
his report on the geology of Maine, estimated that the top of Mount Katah- 
din rose above the ice surface. I visited the mountain in 1870 and found 
fossiliferous drift fragments to within a few hundred feet of the summit, 
just as Professor Hitchcock did, but there has been so much surface 
weathering and sliding toward the top that drift débris would long since 
have disappeared, even if it had once been there. However, without 
insisting on the doubt, if we assume the highest limit of the ice at 4,500 
feet at Katahdin and 1,500 feet at Green Mountain, Mount Desert, we have 
a surface gradient of 27 feet per mile. If the gradient was as moderate as 
this, or near it, we have reason to estimate the zone of subglacial waters 
as pretty broad. : 

The western part of Maine must have been overflowed by the ice 
from the St. Lawrence Valley and Hudson Bay. How far east this north- 
ern ice overflowed Maine is at present uncertain. Without assuming the 
correctness of Mr. Chalmers’s hypothesis of a divergent flow in eastern 
Quebee and New Brunswick as applying to Maine, we must at least con- 
sider it a possibility. Obviously the breadth of the zone of subglacial 
waters of an ice-sheet fed from the far North will be much greater than of 
a local ice-sheet covering the peninsula south of the lower river and Gulf 
of St. Lawrence. Until the doubt as to the condition of northeastern 
Maine is removed it will be unsafe to attempt an estimate of the position 
of the névé line at any stage of the glaciation. 


296 GLACIAL GRAVELS OF MAINE. 


ENGLACIAL STREAMS. 


Recent observations of the Alaskan glaciers warrant the belief that 
englacial streams are sometimes of geological importance, or perhaps it 
might be better stated that the englacial portions of streams that are sub- 
glacial or superglacial for the rest of their course have helped in the 
development of the glacial sediments. 

It is evident that any conditions that prevent the formation of crevasses 
in the lower part of the ice will hinder, if not prevent, the formation of sub- 
glacial tunnels, at least as conduits for waters of surface melting. Where 
erevasses reach only part of the distance down to the bottom of the ice, 
the superficial water would often form an englacial channel along the bot- 
tom of the crevasses. The collapse or blocking of a subglacial tunnel 
would cause the water to rise and escape superglacially, or in case of cre- 
vasses it would form a new channel either at the bottom of the ice or above 
it englacially. In a shrinking glacier the melting of the ice forming the 
roof of an englacial tunnel would leave it as a superglacial stream. The 
stream reported by Russell as rising on the Lucia glacier where it flows 
past a nunatak would appear to have formerly had an englacial channel at 
this place, now become superficial by melting. The situation suggests 
that the course of glacial rivers in such relations may have been deter- 
mined by the fact that the ice of the deep valley at the sides of the nunatak 
was so compressed laterally as it parted and flowed around the hill that the 
basal ice was little broken by crevasses. Crevasses would naturally form’ 
over the top or higher flanks of the hill, but would not reach below some 
point on the hillside. These shallow crevasses were utilized by the stream 
as part of its channel. 

Englacial streams and channels of the ice-sheet may have performed 
two different offices. 

First, they may have amassed glacial sediments directly from the ice. 
Whether we consider them of importance as gatherers of glacial sediments 
will largely depend on our conception of the distribution of the débris in 
the ice. "The only way such streams could directly collect glacial sediments 
would be by melting the ice around the débris and transporting it. The 


| Prof. I. C. Russell, Nat. Geog. Mag., vol. 3, pp. 106, 107, May, 1891. Am. Jour. Sci., 3d series, 
vol. 43, p. 180, March, 1892. Also Prof. G. F. Wright, Ice Age in North America, p. 63, 1889. 


SUBGLACIAL AND ENGLACIAL STREAMS. ZO 


higher the englacial débris rose in the ice the more would the superficial 
and englacial streams be able to collect. Those who believe the englacial 
matter to have been strictly basal will not admit that either class of streams 
would be able to gather much sediment until their beds sank nearly to the 
eround. 

Second, the englacial channels were often simple conduits for streams 
otherwise subglacial. As such, their mission may have been simply to 
protect the ground moraine from erosion, or glacial gravels may have been 
deposited in them. In the last case the stratification of the sediments 
would be generally obliterated by the melting of the subjacent ice. 

In Maine I have discovered numerous places in the line of long glacial 
rivers where the ground moraine is less eroded than in the case of some of 
the short hillside eskers, as, for instance, at The Notch, in Garland. Both 
to the north and south the stratification, ete., are consistent with the 
hypothesis that these were subglacial rivers through most of their course. 
How can we account for so little erosion of the ground moraine? At one 
time I considered these places strong evidence that the osar rivers were 
superficial as a whole, but it must now be admitted that they may imply 
only an englacial or superficial course of a subglacial river for a short 
portion of its length. Thus in the jaws of the narrow pass of The Notch, 
Garland, the basal ice may have been so solid that for a mile or more a 
subglacial river was forced to rise into or on the ice. In 1888 I suggested 
that such accidents might not be uncommon, but without observational 
basis for the idea. Without insisting on close analogies between the 
Alaskan glaciers and the ice-sheet, we must at least consider englacial 
streams as one of the forms of a glacial water action, and probably an 
important one. 


DIRECTIONS OF SUBGLACIAL AND ENGLACIAL STREAMS UNDER EXISTING 
GLACIERS. 


The recorded observations bearing on this subject are too few to 
permit generalization. The courses of only a few of the subglacial rivers 
are more than approximately known. At the terminal enlargement of 
the glacier of the Rhone, the courses of the subglacial streams have 
been mapped, and it is known that some of them flow transversely to the 
direction of ice flow. But this takes place longitudinally and where the 


298 GLACIAL GRAVELS OF MAINE. 


water would find unusual facilities for flowing in almost any direction by zig- 
zagging along crevases. We can not therefore consider this case typical of 
the behavior of the subglacial waters under thicker and less broken glaciers. 

We know that the subglacial streams of ordinary valley glaciers must 
flow approximately parallel to the ice, for the very obvious reason that they 


are confined between the sides of the valleys and can not wander out of — 


them. But such a statement adds nothing to our knowledge of glacial con- 
ditions and can not satisfy us. We wish to know more of the laws that 
govern the formation and maintenance of subglacial channels. For instance, 
in the case of glaciers flowing in meandering valleys, it is well known that 
the line of swiftest ice flow is a curve more crooked than the axis of the 
glacier. Are there conditions under which a corresponding deflection of 
the subglacial rivers takes place along the lines of swiftest motion, or do 
they follow a less crooked course than the axis of the glacier? This and 
many similar questions need to be answered observationally before we can 
understand the drainage systems of existing glaciers, still less of extinet 
ice-sheets. 

We may form two very different conceptions of the relation of the ice 
of the glacier to its waters. 

First, we may consider the ice as static, like the stationary land. ‘The 
waters falling on the earth cut into it valleys and canyons, as do the super- 
ficial streams on the ice. They penetrate its pores and crevices, as glacial 
waters do the snow and ice. They enlarge the subterranean passages into 
watercourses like the subglacial and englacial channels, and in both land 
and glacier these internal channels often overflow on the surface as foun- 
tains. In short, the waters falling on the land, though often employing 
different forces, yet in the end achieve substantially the same results as the 
superficial waters of the glacier. But in all this the land is stationary; it is 
simply obstructive, holding back the water or modifying its flow by friction 
or direct pressure. So also glacial ice as static is nothing but an obstruc- 
tion to its waters. But for the ice the waters would follow the drainage 
slopes of the land; whereas the ice, by simply standing in the way, often 
forces the water to follow crevasses or other channels along lines very dif- 
ferent from the land slopes. In fact, on this conception the ice is simply 
regarded as a rock and its internal water system a part of the subterranean 


drainage. 


SUBGLACIAL AND ENGLACIAL STREAMS. 299 


But second, we may consider the ice of glaciers as in motion. While 
portions of the land are being upheaved the rising terranes are brought 
under the sharper rasp of swifter streams, the earth by its internal move- 
ments thus guiding the development of the erosion. In like manner we 
may view the glacier as in motion, a sort of organism having its internal 
motion so far determined by its environments that it has a systematic devel- 
opment, and each part of the ice must be considered not alone with respect 
to the forces now acting on it, but as having a history, and as often retain- 
ing the forms or structures it obtained long before. This is obviously true 
of the banded structure and other features visible on the surface, and ought 
equally to be true of unseen parts ‘Thus if the basal ice is hollowed out 
by the water that falls down a crevasse at a moulin, the forward motion of 
_ the ice will cause each successive portion of the ice as it advances to that 
place to be also hollowed—the mechanical equivalent of a forward prolon- 
gation of a series of hollows that together make a tunnel but are subse- 
quently modified by the tendency of the stream to enlarge the channel and 
of the antagonistic upward flow of the ice to cause its collapse. Now if 
the ice, having thus, so to speak, gotten the stream in its power, shall 
continue to carry it along the same tunnel prolonged by the ice movement, 
we must consider the ice as having more than obstructive power. By 
virtue of its motion it so exerts its obstructive power in the direction or 
along the line of its motion, that it can be said to have a constructive power 
to help build its own tunnels and determine their courses and develop- 
ment. The moving ice tends to the maintenance of all subglacial and 
englacial tunnels parallel to its flow, while the water with equal pertinacity 
strives to follow the slopes of the underlying land. When the movement 
pushes the tunneled ice over rising ground the water bides its time, and at 
the first eligible transverse crevasse it steals off sidewise toward the lower 
ground. The ice moves onward and prolongs the now unused tunnel 
until it becomes filled by subglacial till or disappears by the collapse of its 
sides and roof. On this conception the actual course of a subglacial or 
englacial river is the resultant of two forces which may or may not be 
antagonistic, viz, the movement prolonging the tunnel in its own direction, 
and the water tending to follow the slopes of the underlying land wherever 
practicable. In this discussion we assume the tunnels; we do not account 
for their origination. 


- 300 GLACIAL GRAVELS OF MAINE. 


It is a matter of observation that even small surface streams generally 
find no difficulty in flowing into crevasses and finding exit by subglacial or 
englacial channels, whereas waters flowing against the sides of glaciers are 
usually dammed by the ice until glacial lakes accumulate. One of the best 
known of such lakes is the Marjelen See in Switzerland, found where the 
Great Aletsch glacier flows past the mouth of a small lateral valley. The 
lake is about a mile long and one-fourth as wide, its longer axis bemg at 


right angles to the glacier. The water of the lake is warmed by the sun, 


and also receives the water of several small streams which, during several 
months of the year, have been warmed on land bare of ice. Many small 
icebergs fall from the glacier into the water and float about the lake. 
Obviously the water of 39° must sink to the bottom, below the reach of 
the smaller bergs, and it will slowly melt away the side of the glacier. 
The fall of the berglets is probably due to the melting of the ice beneath 
them. But although the side of the glacier is thus undermined as it flows 
past the lake, it is not melted away sufficiently to prolong a channel down 
the valley between the ice and the mountain. _ It is only after several years 
that, to use Lyell’s language, owing to ‘‘ changes in the internal structure of 
the glacier,” “‘rents or crevasses in the ice open and give passage to the 
waters.” The pressure is so great that the discharge takes place with a 
loud roaring rush of waters along the central parts of the glacier. That it 
is along the channel of a subglacial river is proved by the fact that toward 
the lower end of the glacier a great quantity of water spouts upward 
through the crevasses and escapes down the steep slope on the surface of 
the ice. It is evident that at the time of the discharge there is a large 
opening into the permanent waterways of the glacier, but for some reason 
the inflowing streams, though in summer warmed on land bare of ice, are 
not able to maintain the channel. It soon closes, perhaps by being pushed 
past the mouth of the lateral valley, and the lake is not able again to force 
an outlet till after the lapse of several years. In the Alps, in Alaska, and 
in most mountainous countries now glaciated, are many similar lakes 
formed in valleys lateral to glaciers, and the Parallel Roads of Glenroy, 
Scotland, and many similar raised beaches found in Sweden and Norway 
mark the sites of ancient but now extinct glacial lakes of this class. 

The inference follows that streams flowing transversely against the 
sides of glaciers do not readily form subglacial outlets beneath them. The 


a 


SUBGLACIAL AND BNGLACIAL STREAMS. 301 


exceptions to this rule are near the distal extremities of glaciers where the 
ice is much shattered. 

Various physical causes can be assigned for the discharge of lateral 
glacial lakes. Thus in the course of climatic changes or cycles it may 
happen from time to time that crevasses open in new places, or they may 
open wider and extend farther than usual toward the side of the glacier, or 
there may be a larger supply of warm water in the lake to enable it to 
melt its way farther into the glacier till an opening is made into a crevasse 
connecting with a subglacial or englacial tunnel. So, too, by reason of its 
greater specific gravity the water tends to float the ice in contact with it, 
the buoyancy of the water beimg resisted not only by the weight of the 
ice next the lake, but also by all the ice cohering to it. Again, the pressure 
of the water is directly tending to rupture the ice. While these and other 
physical agencies are operative in the discharge of glacial lakes, obviously 
it is only by test and observation that we can determine the causes in any 
particular case. 

While, then, the existence of so many lakes lateral to glaciers is proof 
that waters can not find basal passage under glaciers in all directions 
except under the most favorable conditions, yet the fact of occasional dis- 
charge beneath the ice can be cited in favor of the hypothesis that subgla- 
cial rivers can under some conditions flow transversely to the ice of even 
thick glaciers as well as the waters from glacial lakes. 

While the conclusions that can at present be drawn from existing gla- 
ciers are rather meager and demand further investigation as to the courses 
of the imternal streams, yet incidentally they fall in line with many other 
indications as to the streams of the ice-sheet. The osars of Maine are often 
for considerable distances more or less transverse to the existing glacial 
scratches, as well as to the bowlder trains and elongated drumlins, and 
therefore probably transverse to the direction of glacial motion. The 
known instances of the subglacial flow of water transversely to the ice flow, 
admitting the least allowable weight to analogies, indicate that the trans- 
verse direction of the osars can not be held incompatible with their having 
‘been subglacial. 


302 GLACIAL GRAVELS OF MAINE. 


INTERNAL TEMPERATURES OF ICE-SHEETS. 


Surface rocks and soils experience great changes i temperatures, but 
as we descend into the earth we pass beyond the influence of the seasons 
and reach a point of invariable temperature. It has been computed that in 
temperate zones this point lies at an average depth of about 50 feet, vary- 
ing greatly according to the local conditions. In far northern countries 
where there is little snow the earth is permanently frozen after we reach a 
depth of a few feet. 

Without assuming the causes of the ice epoch we can at least assume 
practically Arctic conditions as then prevailing over the region overrun by 
the ice-sheet. It is important to know, if possible, what temperatures pre- 
vailed within that vast body of snow and ice. Was that 4,000 feet or more 
of ice a rock which, like other rocks, had beneath its surface a level of 
invariable temperature? If so, at what depths, and what was the tempera- 
ture? Where did the isogeotherm of 32° he in winter and in summer? 

The only tests made of the temperature of glaciers have been made 
near their distal extremities, where both the ice and glacial waters are 
reported to have a nearly constant temperature of 82°. No observations 
appear to haye been made of the interior temperatures of the névé, and 
we can arrive at only an approximate estimate by reasoning from some 
known facts. In such an investigation we have to depend chiefly on the 
following physical properties of water and ice: 

1. Water has a very high specific heat. 

2. Water and ice are poor conductors of molecular heat, especially ice 
in the form of snow. 

3. Water freezes without change of temperature at the surface of 
freezing so long as any water remains unfrozen, the latent heat of liquidity 
being given up in the act of solidifying. 

4. Ice melts with contraction of volume and without change of tem- 
perature at the surface of melting so long as any portion remains unmelted. 

These properties account for the remarkable power the glacier has of 
regulating its own temperatures. The heat of summer or of the day first 
raises the mass to 32°, and then the surplus is expended in melting some of 
the ice, without change of temperature. In winter or at night the surface 
temperature of dry ice falls like that of other surface rocks, except that the 


INTERNAL TEMPERATURES OF ICE-SHEBTS. 303 


waste is probably slower, owing to its low conducting power and high specific 
heat. The point in the interior where we first reach an invariable tempera- 
ture lies nearer the surface of ice than in other rocks. In addition to these 
properties which make changes of temperature of the ice mass take place 
slowly, the glacier has at its command another most important means of 
maintaining and regulating its temperature. It is known that there is a 
large amount of surface melting over much or all of the névé, and progres- 
sively more as we approach the distal extremity. A large amount of water 
is during the day and summer stored up in the snow of the névé and in 
that contained in crevasses; water is always found in the larger subglacial 
channels, often also in surface pools and crevasses without outlet beneath 
into the tunnels, and in internal cavities in the granulated ice near the surface. 
The moment the temperature at any wet place tends to fall below 32°, some 
of this water is frozen and the temperature maintained. The glacial waters 
thus serve an important purpose in stormg up heat when there is an excess 
above 82° and in giving it out again when there is a deficiency. Those 
parts of glaciers at a distance from water must fall in temperature during 
- the cold of night and of the winter, just like other rocks. 

The net result is that the wet parts of the glacier, i. e., all the region 
of surface melting extending from the distal extremities well up into the 
névé, have the nearly constant temperature of 32°. In summer the isogeo- 
therm of 32° rises to the top of the glacier in all this region, or rather, the 
isogeothermal stratum of 32° includes the whole glacier from the bottom to 
the top. In winter the upper limit of this stratum sinks beneath the sur- 
face an undetermined and varying distance. 

As we go above the zone of wastage into that of accumulation it 
becomes uncertain what are the internal temperatures of the snow fields. 
The addition of new layers of snow is constantly pressing down into the 
interior of the mass the older layers, many of which would have had a 
teraperature far below zero when covered, and must abstract a great amount 
of heat from the interior of the névé. The heat of summer could not 
directly penetrate dry granular snow so far as it could clear solid ice. 
Above the limit of appreciable surface melting it is doubtful if the heat that 
comes from above can pass in large quantity far down into the snow. 
Where the snowfall was very great during the intense cold of winter and 
at high elevations, it might happen that the heat of summer could not pass 


3804 GLACIAL GRAVELS OF MAINE. 


down to the bottom of the previous winter’s snow so as to raise it all to 32°. 
If so, this very cold snow, sinking down toward the ground beneath the 
pressure of later snows, would cause a temperature below 32° to prevail 
downward to some unknown depth, where the heat of the earth would just 
suffice to overcome it and cause a temperature of 32°. The isogeotherm of 
32° might here lie not far above the ground, or even beneath it. 

It has sometimes been assumed that because the surface portions of 
the highest parts of the névé were found dry and powdery there is no 
melting in that region. I am satisfied that inferences founded on observa- 
tion of only the surface of snow are to be received with caution. I have 
seen several places in the Rocky Mountains where water of surface melt- 
ing filtered down through the snow, leaving the surface dry and powdery 
and with no sign of surface melting, or with only'a thin crust which 
the wind soon blew away. In one such case a drift about 20 feet deep 
had formed on the frozen ground. Soon after a warm wind melted con- 
siderable snow, and then followed two weeks of very cold weather, when the 
- mercury stood at or below zero most of the time. The temperature of the air 
was still below the freezing point when an excavation accidentally revealed 
the fact that the lower part of the drift to a depth of 4 feet was moist and 
part of it was almost slush. No stream or spring was here and the earth 
beneath was frozen. It was evident that the moisture was due to water of 
surface melting that had seeped down through the snow, leaving no sign of 
its former presence to the eye of an unguarded observer. No limit can be 
set to the distance that water will pass into snow as into sand, provided it 
does not reach a stratum having a temperature below the freezing point. 

Summary.—A]l those parts of glaciers where there is enough melting to 
furnish water and store more of it in summer than freezes in winter have 
the constant temperature of melting ice irrespective of season. Over all 
the zone of waste the glacier has the internal temperature of 32°, while the 
temperature of the dry surface ice varies with the seasons, but can never 
rise. above 32°. Under this part of an ice-sheet the bottom of the ice is 
never frozen to the ground, but is bathed by at least a molecular film of 
water. The ground and the subglacial till are here unfrozen. As we go 
above into the area of accumulation the internal and basal temperatures 
are variable and uncertain. 


GLACIAL SEDIMENTS. 305 


BASAL WATERS OF ICE-SHEETS. 


Ice-sheets covering all the land obviously receive beneath them no 
water from adjoining land bare of ice. 

The waters found beneath ice-sheets are due to various causes, as 
follows: 

1. Water of surface melting that has gotten beneath the ice through 
crevasses. This is by far the largest source ef subglacial waters. 

2. Basal melting due to the internal heat of the earth. This normally 
occurs under all the parts of the glacier and névé having a basal tempera- 
ture of 32°. Assuming the correctness of Taine’s estimate of the internal 
heat, the annual basal melting equals a stratum having a thickness of 0.36 
inch covering an area equal to that of the ice. This might be modified by 
the circulation of subterranean waters. 

The fact that the subglacial rivers continue to flow during the winter 
has sometimes been urged as a proof of basal melting. But it is known 
that in winter the larger crevasses become filled with a large amount of 
snow, even down to the distal extremity of the glacier. This snow partly 
melts, partly sinks into the depths, where it is only slowly consolidated to 
ice. So also in the zone of surface slush there is a large quantity of snow 
capable of holding water like a sponge. It is certain that there is a large 
amount of unconsolidated snow on all large glaciers or withim their wounds 
that is saturated with water at the end of summer. These granular masses 
act, like the soils and other porous strata, as reservoirs to moderate the 
flow, and thus they hold back the water till long after surface melting has 
ceased for the season. Waters of springs issuing from the earth would 
continue to flow during the winter. We can thus account for large streams 
continuing to flow from glaciers during the winter irrespective of basal 
melting from the internal heat of the earth. Such melting in winter must 
be proved by other evidence than the mere presence of water beneath the 
glacier at that season. 

3. Basal melting caused by friction of the ice against its bed. 

In connection with the friction of the ice against the underlying rocks 
and till, we may also consider the friction of débris held in the ice against 
the bed or of one piece against another. When we consider the great amount 
of rock that was planed off beneath the ice-sheet and reduced to rock flour 


or broken into fragments, we must conclude that the doing of so great an 
MON XXXIV 20 


306 GLACIAL GRAVELS OF MAINE. 


amount of mechanical work was inevitably accompanied by a considerable 
development of heat from friction. Its quantity would depend on many 
variables, such as the coefficient of friction of the ice against different kinds 
of rock, the pressure and rate of motion of the ice, the amount of englacial 
matter, ete. It is well known that beneath landslides and avalanches con- 
siderable frictional heat is developed. Whether the heat generated by the 
slower motion of the snow and ice will cause basal melting depends on the 
basal temperature of the mass. Where available for melting, heat from this 
cause might considerably augment the basal waters, but the quantity is 
unknown. 

4. Basal melting due to heat transmitted from above through the ice. 

Croll’s theory of glacial motion seems to involve the hypothesis that 
heat can be transmitted from a particle of water to a particle of ice without 
a difference of temperature to act like the electromotive force to drive it. 
Without involving ourselves in dynamical questions, we can for the time con- 
sider the ice as static, and assume that the passage of molecular heat in it is 
from particle to particle by the process of conduction from where there is a 
higher to a lower temperature. It follows, since all the lower portions of 
glaciers have the temperature of 32°, that the heat contained in the ice can 
not, unless pressure changes the melting point, pass out of one part of the 
ice to produce melting of another part of the same body of ice. Omitting 
from the present discussion the questions involved in the varying melting 
point of ice under varying pressures, we are justified in the conclusion that 
molecular heat from the surface will be conducted downward until the tem- 
perature of all the mass is at 82°, and then no more can pass, for the ten- 
sion, to use the electrical term, is then equally high in every part. But in 
the form of ether vibrations energy can penetrate the ice irrespective of 
temperature. The rougher and more granular condition of the ice near the 
surface indicates that most of the radiant heat is absorbed soon after passing 
into the ice—i. e., is converted into molecular heat and causes melting at a 
multitude of places. The reflections from the surfaces of these cavities 
containing water causes the opaque and granular appearance of surface ice. 
But it is well known that the words ‘‘transparent” and ‘‘ opaque” are rela- 
tive terms, referring only to visual rays, not to all the waves of ether energy. 
It seems probable that the rays capable of producing photographic effects 
on silver salts, and all the rays visual to the eye, are absorbed by water 


BASAL WATERS OF ICE-SHEETS. 307 


and ice before reaching a depth of many hundred feet. But there are 
abyssal animals in the sea far below those depths, and they have eyes, prov- 
ing that even at such great depths ether waves of low refrangibility are not 
absorbed by the water. The passage of radiant energy from the sun and 
stars into the ice will be affected in considerable degree by the condition of 
the ice surface. The rougher and more broken the surface ice, the larger 
the proportion that will be refracted and reflected and radiated outward and 
lost or absorbed in the surface ice. A residue remains of rays not absorb- 
able by the ice or absorbed only after traveling a long distance in it, which 
may be transmitted through it till they come to englacial débris or to the 
ground. Here, being absorbed in part, they become changed to molecular 
heat and melt the adjacent ice. While the passage of stellar and solar 
radiations to considerable depths in the ice is probable, the quantity is 
unknown and has not been proved by observation. If we could prove that 
any considerable amount of heat was thus transmitted through the ice, it 
would greatly help to account for the accumulation of drumlins and the 
glacial gravels and the dropping of englacial matter to become part of the 
subglacial till, it would account for a part of the glacial waters and for 
the maintenance of the internal temperature, and it would perhaps help to 
answer the question, What effect did the pressure of surface waters, streams, 
pools, and shallow lakes have on the development of the subglacial till 
beneath them? For surface waters would somewhat help to make the ice 
more transparent, like a piece of ground glass flowed with water, and we 
know that the larger superglacial streams remove the granular ice and reveal 
only the clear solid ice in their beds. Such an hypothesis, if proved, would 
be a welcome addition to our knowledge of glacial conditions, if for no 
other reason than to account for the fact that the ice, after having taken 
the englacial débris into its grasp where it is thicker, lets go of it again 
subglacially where the ice is thinner. 

5. Subterranean waters issuing as springs beneath the ice. The rocks 
beneath glaciers become charged with water, just as they do elsewhere, and 
probably discharge it under the ice in many cases. Such waters would dis- 
turb the distribution of the internal heat of the earth. In their subterra- 
nean courses they would absorb some of the internal heat and transfer it to 
their place of issuance. If this was beneath the ice, the heat would be 
available for melting or maintaining temperature. 


308 GLACIAL GRAVELS OF MAINE. 


6. There is another possible, though hardly probable, source of subgla- 
cial waters, which we admit into our list simply as a subject for investiga- 
tion. Possibly it depends for its basis wholly on our ignorance of the 
structure of the névé. It has often been observed that at the margin of 
the snow fields the solid ice extends under the snow. In the Mount St. 
Elias region Russell has seen it to a depth of 100 to 200 feet beneath the 
snow. But the snow there does not melt at elevations above 13,000 feet, 
but comes down as avalanches upon the névé. These conditions can not 
be typical of ice-sheets, for though the latter may perhaps sometimes rise 
above surface melting, there are no avalanches to compact the ice, nor any 
crevasses to admit water from rocks nearly bare of snow. Both Russell 
and Chamberlin regard it as probable that even in such a supposed ice- 
sheet the dry névé grows more compact as we go downward, and finally 
becomes solid ice. A hole bored to the bottom of the Greenland névé 
would answer all these questions of fact, but in the absence of observations 
it must be considered as possible that there are conditions under which the 
coarse granular snow or partially consolidated ice extends beneath the zone 
of surface melting, so as to become charged with seeping water, and near 
enough to the ground to permit its contained water to escape to the bottom 
of the ice without the aid of crevasses as the grains are slowly pressed 
together to form consolidated ice. This could happen only under snow 
fields unbroken by crevasses. If this ever happens, the granular zone would 
form the fountain head of subglacial streams. 


BASAL FURROWS AS STREAM TUNNELS. 


As the glacier flows over an obstruction a furrow is formed in the base 
of the ice. Though viscous to a certain extent under ordinary pressures, 
the ice can not at once fit itself to the lee side of the obstruction. This is 
proved not only by the general laws of the flow of fluids but also by field 
phenomena, such as the subglacial till that has been seen to gather beneath 
the ice of a tongue that crossed a low part of a hill m Greenland, the 
phenomenon of crag and tail, the existence of hollows in the rock that 
were glaciated not at all or only imperfectly, ete. The ice does not always 
change its direction and bend downward when the rock surface does so, 
and thus small caves may exist beneath the ice. This is proved by the 
facts elsewhere recorded as observed at Rockland. It is to be noted that 


BASAL FURROWS AS STREAM TUNNELS. 309 


this happened only while the latest scratches were being made. An earlier 
series of scratches went up and over and down the slope of the rock with- 
out distinguishable break of continuity. These scratches do not date from 
the time when ice was deepest, but are themselves deflected from the direc- 
tion of general glaciation, yet at the time they were made the ice could 
flow down into depressions without leaving caves beneath it. The scratches 
on the tops of the highest hills date from the time the ice was deepest, and 
scratches parallel to this direction are remarkable for the depth of the 
depressions they go down into and the abruptness of the slopes they are 
able to follow. A fair inference is that the furrows or hollows left beneath 
the ice while passing over uneven ground, bowlders, and other obstacles 
are a feature of thin glaciers. Many observers have seen such furrows in 
the lower surface of the ice where it towed over bowlders, but their obser- 
vations were necessarily made in the crevassed portions of glaciers near 
the extremities. Such furrows must fill up by inward flow of the ice, 
and the rate would depend on pressure, ete. 

The hypothesis that basal furrows and lee cavities have helped to form 
subglacial stream tunnels has some quasi support from certain field phe- 
nomena. ‘Thus in the coast region the gravels are often found on the tops 
of low hills, but in such places it is probable that crevasses would be formed, 
and these might aid in the formation of tunnels far more than the basal 
cavities. None of the hillside eskers have been seen to originate from 
bowlders or sharp peaks of rock, or to have such in their courses. The 
bosses of rock that are sometimes found in the course of an osar river are 
so low and broad that only very short cavities would form in their lee. 
And since such cavities were largest near the extremity of the ice, where 
crevasses were most numerous and sufficed to carry off the waters, we must 
infer that basal furrows and caves were of little use in establishing stream 
tunnels. 

Another conceivable sort of basal cavity attracts attention as a possi- 
bility. Under unbroken ice the water of basal melting would be pressed 
sidewise from where there is greater pressure to where there is less pressure, 
and collect beneath the ice. Since water is practically incompressible, such 
a water-filled cavity can not collapse in one part without a corresponding 
expansion in another. It would in some respects be the analogue of the 
air bubble in water, though not owing its shape to surface tension, and, like 


310 . GLACIAL GRAVELS OF MAINE. 


the bubble, could be pushed forward, to be discharged into the first crevasse 
or cavity formed in lee of an obstruction. By some such process the basal 
waters are able to maintain a precarious and much-interrupted passage 
beneath the ice. 

At North Dixmont and elsewhere osars that are somewhat transverse 
to the glaciation are stratified monoclinally, the dip being toward the lee 
side, as if the advance of the ice continually closed up the stoss side of the 
enlarging channel and left a corresponding opening on the lee side. 


GENESIS AND MAINTENANCE OF SUBGLACIAL AND ENGLACIAL CHANNELS. 


Of this intricate subject our definite knowledge is phenomenal and 
general rather than causal and detailed. Rivers are known to flow within 
or beneath the ice. The surface waters plunge down crevasses and disap- 
pear. These facts are well known. But as to the parts of the work 
wrought respectively by the ice and the water, these and many similar 
questions can be argued, but not determined by direct observation. 

No other means than crevasses for the passage of superficial waters 
beneath a sheet of ice covering all the land has been discovered. If inter- 
stitial water reaches the ground through granular snow and consolidating 
ice, or if surface pools melt their way to the bottom, these processes would 
hardly merit naming as exceptions to the foregoing rule, since they could 
supply so small an amount of water. We have, then, to consider the ice- 
sheet as one of the rocks which surface waters penetrate, as they do other 
rocks, along a system of joints and crevices of wonderful complexity till 
they reach the earth or the bottom of the crevices. Thus in the first 
instance the ice itself provides the means for the descent of the waters. It 
is at the escape of the waters horizontally that difficulties begin. Gen- 
erally the streams are longitudinal, while the greater part of the crevasses 
are transverse. The transverse crevasses break up the glacier into parallel 
blocks or prismoidal slices, each of which, judging from surface appear- 
ances, is capable of acting as a dam to. hold back the waters above it. 
Where the ice is broken longitudinally or, as not infrequently happens, 
alike transversely, longitudinally, and obliquely, the waters find no diffi- 
culty in making their way by zigzags through the labyrinth of crevasses. 
But it is known that surface streams often sink into the ice far above the 
greatly shattered portions of the ice-sheet. There must be subglacial or 


SUBGLACIAL AND ENGLACIAL CHANNELS. onl 


englacial channels under long reaches of ice unbroken at the surface, and 
it is not admissible that they were formed along longitudinal or any other 
crevasses. The problem is solved so far as the much-crevassed ice is 
concerned. It now remains to inquire how we can account for the exist- 
ence of longitudinal channels within or under parts of the ice solid on thé 
surface, or if broken, not longitudinally, but transversely into long prismoids 
attached at the ends to unbroken ice, so that apparently they ought to dam 
the subglacial waters. ; 

At the outset we are confronted by another query: How nearly do 
the surface crevasses represent those of the bottom? Except at precipices, 
crevasses form at right angles to the tension, or nearly perpendicular to the 
ice surface. Usually they are not planes, but more or less curved and 
irregular; but even when approximately plane when first made, they 
become greatly distorted by the unequal flow of the ice. Also, since the 
upper ice moves much faster than the lower, the successive fractures divide 
the ice into blocks that are much wider, lengthwise of the glacier, at the 
top than at the bottom. When the ice has great depth and rapid motion 
and crevasses form at short surface intervals, the bases of the prismoidal 
slabs must often be narrow, and it may even happen that the crevasses 
meet at the ground or above it. We must admit, therefore, that the basal 
ice is broken by crevasses nearer together than at the surface, and also that 
by the intersection of curved and irregular crevasses it may not seldom 
happen that transverse slabs of ice that appear on the surface to be capable 
of acting as dams to the subglacial waters are broken through in the 
depths. After making a most liberal allowance for cases where there are no 
apparent longitudinal crevasses but yet the transverse crevasses connect, we 
still have a residue of apparently unbroken ice penetrated by longitudinal 
subglacial streams. 

Into all crevasses the surface waters pass. Part of the crevasses do 
not reach to the ground; part open into subglacial channels and part do not. 
Those crevasses down which the waters succeed in forcing a passage are 
soon enlarged into the shaft or well of a moulin. This enlargement is 
significant and must be accounted for. At the instant of melting, the 
surface water has the temperature of 32°, but under sunlight it absorbs 
heat and rises in temperature. The water in contact with the ice then gives 
up its surplus heat to melt a portion of the adjacent ice. This is a slow 


See, GLACIAL GRAVELS OF MAINE. 


process, since water is a poor conductor of molecular heat, while the absorp- 
tion of radiant energy is practically instantaneous. Volumes are as the 
cubes of the diameters, and surfaces as the squares of the diameters; hence 
the larger superficial streams contain a larger proportion of water warmed 
above 32° as they pour into the ice. This heat melts the ice of the 
crevasse as it descends and enlarges the passage into a shaft, and continues 
the work after it is beneath the ice in the enlargement of even the narrow- 
est crevasses into tunnels. Water at 32° would find its way through the 
crevasses as do the subterranean waters through the joints of the insoluble 
rocks, without enlarging the natural joints except to a limited extent by 
mechanical erosion. Surface waters of the ice never become heated very 
much above 32°, and their melting power is much more feeble than waters 
warmed on the land. 

Crevasses not opening into established subglacial or englacial channels 
may become filled with water in which convective currents soon begin to 
carry heat to the bottom, since water at 39.1° sinks and forces that of 
32° to rise. But crevasses are so deep in proportion to their width that 
only a sluggish circulation can be kept up in them, and rarely, unless 
in exceptional cases, will stationary water be able to melt for itself a sub- 
glacial outlet. The flow of a surface stream over the mouth of the crevasse 
aids the melting by furnishing a constant supply of warmed water. 

When a superficial stream pours down a crevasse, an enlargement of 
the base of its shaft is formed, where the water, falling at a high velocity 
to the ground, rebounds outward in all directions. A new crevasse soon 
opens at a short distance above the last one, and in the course of time the 
stream opens a new shaft in this and abandons the old one. As the ice 
flows past the place where the crevasses form, each part is in succession 
hollowed out at the base of the waterfall, and thus a large continuous 
tunnel is prolonged by the forward movement of the glacier. It is not 
meant to imply that the water acts only at the base of the waterfall, but it 
acts there most energetically. Given, then, a waterfall or any other condi- 
tions whereby warmed waters can melt a passage underneath each suc- 
cessive block between the crevasses, and the glacier itself will prolong a 
tunnel distally. 

Let us take the case of a moulin supposed to be formed at the proximal 
end of a subglacial stream—the successive transverse crevasses not opening 


SUBGLACIAL AND ENGLACIAL CHANNELS. 313 


into one another but separated by a solid slab of ice. When a new cre- 
vasse forms, it becomes filled with water, but it is narrow, and melting by 
convection currents is very slow. Under a pressure of thousands of feet the 
water searches out every point of weakness. It acts by its pressure to rup- 
ture the ice, also to penetrate between the ice and the underlying rock, and 
also by its superior weight to raise bodily the ice in contact with it. The 
last can not be done without fracturing ice of great thickness, and this the 
flotation is not able to do. The line of contact between the ice and the rock 
is that of weakness, since the adhesion of the ice and rock is less than the 
cohesion of the ice, and probably of the ground moraine, where there is 
one. If the ice has been held above the rock by a film of basal water, or 
there is a basal furrow in the bottom of the ice, the water immediately 
penetrates between the ice and the rock, and soon enlarges the smallest 
chink to the capacity of the stream. Moreover, the ice must flow down 
into each scratch of the rock or the trickle will begin and all the rest 
follow. Whether ice held under great pressure in fair contact at all points 
with the rock could prevent the passage of the waters is a matter of con- 
jecture. It is possible that continued pressure might cause a minute flow 
of the ice, so as slowly to raise in arch form the central parts of the block 
forming the dam, and thus permit the water to escape. Only the minutest 
opening would be required to initiate the flow, and the melting would do 
the rest. 

It is known that ice can flow over deeply buried ridges without being 
crevassed at the surface. If the-motion continues while the thickness 
diminishes, the time will come when the ridge will cause an increasing 
bulging of the ice surface, and finally crevasses. In many cases of retreat- 
ing glaciers surface waters are seen to pour down crevasses that would not 
exist when there was considerably deeper ice, and in these cases the waters 
must have established subglacial or englacial channels for themselves not 
very long ago. At the moulin, where the water in the new crevasse is 
separated from a large tunnel by at most only a few feet of ice, it is not so 
wonderful that it finds a passage. The difficulty is to show how a channel 
is for the first time established beneath or within the ice, often underneath 
long reaches of ice unbroken at the surface. It is constantly being done 
on the glacier longitudinally, yet the large Marjelen See can not keep open 
a permanent channel transverse to the ice flow. We seem to be driven to 


314 GLACIAL GRAVELS OF MAINE. 


the conclusion that the motion of the ice not only indirectly establishes the 


subglacial drainage by furnishing the necessary crevasses, but also directly 
aids in the formation of the channels in the direction of motion. This it 
does because the modifications of the base of the ice that are made as the 
ice passes a given point are carried forward by the motion. As one of the 


possible combinations, let us postulate a new crevasse appearing far from | 


any others, opening into the basal cavity formed in the lee of the obstruc- 
tion causing the crevasse, and where no previous water channel exists. 
When the crevasse fills with water, its outward pressure, owing to the 
higher specific gravity of water, somewhat exceeds the pressure due to 
the weight of the superincumbent ice. The mward flow of the ice to 
fill the cavity in lee of the obstruction is resisted by the viscosity of the 
ice and the antagonistic pressure of the water. In the absence of specially 
great pressure, such as would be caused by converging ice flow owing to 
lateral pressure of obstructions, it might happen that the pressure of the 
water filling the crevasse and basal cavity could resist the collapse of the 
latter, or make it very slow. If so, as the lower ice moved forward, the 
water would fill the lengthening furrow which would extend from the base 
of the crevasse backward to the obstruction. When a new crevasse was 
formed at the proximal end of the same cavity, the water pressure would 
still be maintained, and would continue while the base of that crevasse was 
in turn pushed forward. Under favorable conditions the basal furrow 
might thus be prevented from collapsing until its forward end had been 
brought to where it opens into other basal cavities or into a crevasse. In 
‘this analysis we have avoided a comparison of the pressure exerted by the 
inward flow with that due to the weight of the ice. Without insisting on 
details where so much remains unknown, we may in a general way safely 
affirm that the motion of the ice greatly assists in the formation of sub- 
glacial tunnels in other ways than simply by the formation of crevasses. 
Probably a mass of motionless ice would have only a surface drainage. 
How are the channels of subglacial streams maintained transversely to 
the movement? Where transverse crevasses form a part of such a channel 
it is easy to account for the maintenance of the channel. As new crevasses 
opened, the stream would occupy them in turn for a time, and then abandon 
them, as it did old moulin shafts. This implies that the stream is pushed 
onward, whatever distance intervenes between the successive crevasses, and 


SUBGLACIAL AND ENGLACIAL CHANNELS. 315 


then returns to its old position in the latest crevasse. Probably all subgla- 
cial tunnels wander, but the transverse ones more than the longitudinal. 
A transverse channel could be stationary in two ways: by the melting of 
the ice as fast as it advanced, or by becoming filled with sufficient gravel 
to force the ice to flow over it. The stratified osars date from a time when 
the channels were approximately stationary, due probably to both the above- 
cited conditions, aided perhaps by a sluggish ice movement. 

The same causes which enlarge crevices into tunnels maintain the. tun- 
nels against a slow inward movement of the ice. An instance is seen on 
the Malespina glacier, where the subsidence of the roof of a glacier river 
has resulted in the formation of scarps of depression on the upper surface 
of the glacier. That glacial rivers do not succeed in eroding so broad can- 
yons and tunnels in the ice as they would in rock is due partly to the 
gradual collapse of the walls and partly to the fact that the glacier is ever 
being renewed. 

While we postulate some inward flow, the assumption must be so held 
as to allow the formation of crevasses, which we can not account for if we 
assume very much fluency or plasticity. 

In case of a decaying ice-sheet having its névé and higher ice unbroken, 
the thinning of the ice over the hills would from time to time cause the 
appearance of crevasses at places before free from them. New subglacial 
tunnels would soon be formed, if surface waters flowed into them. Thus, 
in Maine, as the névé retreated northward, there would be a corresponding 
advance of the subglacial rivers, so far as they serve to carry off superficial 
waters. The advance would take place into a region previously drained by 
superficial streams. The thinning of the ice would cause a multitude of 
crevasses to appear in new places, but many of these would be of no sig- 
nificance. To use a biological phrase, there would be a natural selection 
of the crevasses, only those intersecting the established superficial streams 
having the power to determine the courses of the larger subglacial rivers to 
that place. In this manner the superficial drainage systems of the ice-sheet 
may have had an important influence in determining the number and courses 
of the subglacial rivers. 

It is difficult now to ascertain the causes of the dividing of the ice- 
sheet into superficial drainage systems or how far it was determined by the 
underlying hills. There may be parts of the slush zone that are so flat 


316 GLACIAL GRAVELS OF MAINE. 


that the courses of the surface streams are determined by the accidents of 
the winter snow drifts. Many observers report seemg domes and rounded 
ridges on the ice, presumably formed by some buried obstruction. Instru- 
mental surveys might reveal shallow anticlines or synclines where to the 
eye there was a plain. Where ice flows over a ridge that is parallel to its 
motion there will be a bulging at the stoss end of the ridge, and probably 
then to leeward there would be a shallow valley on the top of the ridge for 
a considerable distance, caused by the retardation of the flow at the bulg- 
ing. But in Maine the hills were mostly transverse, and the transverse 
billows of the ice-sheet would be more numerous and higher than the 
longitudinal ones. It is certain that the osar rivers penetrated the higher 
hills by low cols and passes. In many cases, especially in western Maine, 
they must have been subglacial rivers. It is as yet uncertain whether we 
are to attribute the courses of these subglacial rivers wholly to conditions 
existing within or beneath the ice, or whether we can trace additional links 
in the chain of causation and can declare that the courses of the subglacial 
were in part determined by those of the superficial streams, and that these 
in turn were determined to the low passes by the undulations of the surface 
ice as it flowed over the adjacent hills. Such an investigation could not 
proceed far without the aid of a topographical map. The facts im the field 
certainly seem in numerous cases to favor the hypothesis. The topic will 
be referred to later. 


FORMS OF GLACIAL CHANNELS. 


Observation proves that the subglacial and many of the englacial 
channels have arched roofs. This is chiefly due to the fact that the waters 
are always in contact with the lateral walls, but only in time of flood can 
they reach to the roofs to melt them, and partly because water of 39.1° tends 
to sink to the bottom. In case of a roaring stream this would have little 
effect, but it might be an important element in case of a quieter flow, as 
when a stream enters an enlargement of its channel or goes up and over a 
hill. That the melting is most rapid near the bottom of a cavity that con- 


| Lieutenant Peary, Bull. Am. Geog. Soc., vol. 19, p. 287, 1887, says: ‘‘As to the features of the 
interior beyond the coast-line, the surface of the ‘ice blink’ near the margin is a succession of 
rounded hummocks, steepest and highest on their landward sides, which are sometimes precipitous. 
Farther in, these hummocks merge into long flat swells, which in turn decrease in height toward the 
interior, until at last a flat, gently rising plain is reached, which doubtless becomes ultimately level.” 
See also Prof. I. C. Russell, Nat, Geog. Mag., vol. 3, pp. 106, 107, 132, May 29, 1891. 


ENLARGEMENTS OF GLACIAL CHANNELS. SILT 


tains water warmed above 32° is proved by the overhang at the margin of 


glacial lakes and by the enlargement at the bottoms of glacial pools and 
lakelets. On Hagues Peak, Colorado, is an ice field that is sliding, if not 
flowing, and the walls of the subglacial outlet of a small lake overhang at 
an angle of 45° or more in a curve convex downward. 

In case of superficial and englacial channels the bottom as well as the 
sides is more or less melted and eroded by the glacial waters; hence the 
base does not enlarge laterally so much as when the bed is composed of 
rock, and such streams gen- 
erally form more canyon- 
like channels. But if they 
succeed in melting their beds 


downto the ground the chan- Fre. 25—1deal sections across channels of superficial glacial streams. 
3 a, before reaching the base; b, after reaching the base. 
nels then begin to enlarge 
at the base, and the walls to overhang, like those of a subglacial stream. 
Gravel deposited in such a channel would be a ridge with arched cross 
section, like that found in a subglacial tunnel. 

The accompanying cut (fig. 25) was drawn in 1888, and can be com- 
pared by the critical reader with the more recently published photographs 
of the Malespina glacier by Russell. 


EXTRAORDINARY ENLARGEMENTS OF THE GLACIAL RIVER CHANNELS. 


When we follow one of the ordinary osars for 50 miles, we become 
greatly impressed by the narrowness and steepness of the ridge. Some 
of the hillside and smaller osars are, toward their northern ends, only 5 to 
15 feet wide at the base. Their material here is very little worn and 
rounded, and the streams that deposited them were brooks. The height of 
the osar proper usually exceeds one-eighth, and sometimes locally reaches 
to one-fourth or one-third, of its base. hat rivers capable of transporting 
so great a quantity of sediment should occupy so narrow channels is truly 
wonderful when we consider the softness of ice as compared with the 
hardness of the débris transported and its consequent liability to mechan- 
ical erosion, also that it was liable to melting, a process which has its 
analogue in the action of subterranean waters or calcareous rocks, and 
might be expected to result in the formation of subglacial and englacial 
channels comparable to the great limestone caves. That the glacial rivers 
do not ordinarily succeed in doing this is due, I conceive, chiefly to the 


318 GLACIAL GRAVELS OF MAINE. 


constant renewal of the living glacier. Canyons cut in rock exhibit the eumu- 
lative effects of erosion on a fixed bed. But the ice-sheet of to-day is not 
that of the last century. Pressing onward from age to age, just as new gener- 
ations of men rise to do the world’s work, the worn, rounded, and wasted 
glacier loses itself at the glance of the sun, before its streams have time to 
enlarge their channels very greatly, and is replaced by a new and unbroken, 
youthful glacier, eager to run its race. The slow inward flow of the ice 
also assists in preventing enlargement of the channels of the streams. 

In addition to the small narrow ridges we find others broadening to an 
eighth of a mile or more, with corresponding height, or expanding into 
massive ridges or mounds one-half to three-fourths of a mile in breadth 
and a mile or more in length, with a height of 100 to 150 feet. We find 
hundreds of miles of osar terraces one-eighth to one-half a mile in breadth, 
level in cross section or with a central ridge rising above the rest of the 
plain, going up and over hills or skirting hillsides as terraces in a way 
to prove they were at the time of deposition confined on one or both sides 
by ice. We find cones, domes, mounds, and ridges of very small as well 
as large size, but all in situations such that they must have been deposited 
in channels or basins in the ice. We find osar border clay deposited in the 
broadened channel of an osar river, which is in some cases probably marine— 
i. e., an osar channel became a fiord in the ice. We find channels of the 
ice one-fourth mile to a mile wide filled with deltas which at their distal 
ends are marine. From a diminutive osar like one of the ridges near 
South Acton or the little gravel hummocks near the Head of the Tide, 
Belfast, up to the Whalesback, Aurora, or the so-called ‘““mountains” of 
Greenbush, or the broad osar terraces of York and Oxford counties, the 
distance is immense. Before the final disappearance of the ice-sheet it 
was gashed and pierced and sliced by a complex system of channels, most 
of the time of large size and irregular shapes. Is this self-destructive? If 
so, it is no more suicidal than the behavior of a glacier could be expected 
to be that was forced to supply water for its own destruction. The drainage 
waters of ordinary Alpine glaciers immediately escape, but this ice-sheet 
went over many transverse hills, and to the north of the hills there were 
large permanent bodies of water which toward the last were eating out its 
vitals. To complete its misfortunes the sea rose, and by the greater sub- 
sidence to the northwest it found itself on a bed sloping against it over 


DIRECTIONS OF GLACIAL RIVERS. 319 


large areas. In the time of its strength the ice-sheet could so far strangle 
its rivers that only a little sediment was left in their channels, but the 
sediment was poured out in front of the ice where the sea now is. But in 
its decay, when the flow became sluggish and even the ground turned 
against it and imcreasing quantities of solar heat were transmitted through 
the ice, the gravel was left far back of the ice front. In the Rocky 
Mountains substantially all the glacial gravels were frontal or overwash 
plains, and the same was true of large portions of the northwestern Interior. 
In Maine the marine deltas and a large part of the reticulated kames were 
deposited in front of the ice, also much of the valley drift; but in addition 
to these there is a very great development of gravels that were deposited 
within the area then covered by the ice. For the great enlargement of the 
glacial stream channels we need invoke only the same causes that first 
established them as tunnels. Mechanical erosion, melting by warmed 
waters, and heat transmitted through the ice, are sufficient to do the work 
when acting through thin ice whose motion was sluggish or in places 
almost arrested, aided by the rising sea, the bodies of water lying to the 
north of the hills, the increasing quantities of water warmed under the 
sunlight either by the melting of the roofs of their tunnels or their being 
forced up onto the ice by the clogging of their channels, etc. Toward the 
last probably most of the water in the channels of the broad osars or osar 
terraces was exposed to the sunlight. If the narrowness of the early osars 
is remarkable, the broadness of the later ones is equally remarkable. 

These extraordinary enlargements of the stream channels were made 
in the last days of the ice at the place of enlargement, all the other condi- 
tions being favorable. Mechanical erosion was active, but still more effect- 
ive was that insinuating, ever alert agent, heat, whose transformations within 
the decaying ice-sheet were varied and powerful. 


DIRECTIONS OF GLACIAL RIVERS COMPARED WITH THE FLOW OF THE ICE. 


Our definite knowledge of the courses of the rivers of the ice-sheet is 
derived from the sediments they have left behind them and the excavations 
they made in the till and the solid rock. When we map the gravels, we 
map only those portions of their channels im which sediment was deposited. 
In large portions of their courses the flow must have been too swift to per- 
mit the deposition of sediment. While it is impossible now to reconstruct 


320 GLACIAL GRAVELS OF MAINE. 


the map of all the streams of the ice-sheet, enough is known to enable us 
to mark out the courses of the larger rivers. In some cases the gravel is 
residual rather than transported—that is, the streams had barely power to 
carry off the finer matter of the till, leaving the larger fragments with but 
little, if any, water transportation from the place where the ice brought 
them. In a multitude of cases no doubt small trickles and brooklets car- 
ried off some of the finer matter of the till, leaving it a little more sandy 
than the usual till, but such we can hardly trace. In a number of places 
glacial streams formed potholes, but have left no gravels. In places 
we find the ground moraine eroded and glacial gravel left at some point 
southward. 

Although the general or average directions of the rivers were roughly 
parallel to the direction of ice flow, there are many important divergences. 
Most of the shorter meanderings are plainly transverse to the scratches on 
the rocks, and so are some of the larger zigzags of 5 to 30 miles. The maps 
show that a number of the osar rivers had tributary branches like those of 
ordinary rivers, and at their places of junction I have found no proof from 
the scratches that there was a similar convergence of the ice movements. 
In like manner, where the delta branches diverge, there is no corresponding 
divergence of the scratches. They diverge or converge at large angles up 
to a right angle, and it is difficult to conceive causes for such ice move- 
ments. It is true that the latest ice movements were recorded by shallow 
scratches on rocks bare of ground moraine, and from which the glaciated 
surface has now generally weathered, aided hy forest fires or by those made 
in clearing the land. But after making the largest admissible allowance 
for the imperfections of the record it is still difficult to assign causes for 
such a converging flow as must have taken place near the head of Penobscot 
Bay (the reader is referred to the map, Pl. XX XI, for explanation), or in 
Greenbush, or near Tomah station of the Maine Central Railroad. As 
elsewhere noted, there is a convergence of glacial rivers toward Columbia 
and Jonesport. The scratches also converge toward the same region, but 
not so much as the rivers. The Coast Survey charts give the soundings for 
a few miles off the coast, and I fail to find any deep valley in the sea floor, 
or other topographical reason for such a converging flow of the ice; and 
there is just as little topographical reason for the flow of the rivers for 30 
miles or more transversely to the ice movement, as testified both by 


TOPOGRAPHICAL RELATIONS OF GLACIAL RIVERS. 321 


scratches and bowlder trains. I see no admissible interpretation but this: 
Osars for long distances are transverse to the recorded glacial movements, 
and probably even the latest ice movements were not parallel with them. 
In the coast region, as near Belfast, there are usually one or more systems 
of glacial scratches that diverge progressively more and more from those 
that mark the time of deepest ice, the latter being parallel to the scratches 
found on the tops of the highest hills. Here we find the systems of dis- 
continuous gravels approximately parallel to the scratches last made, and 
convergent like them, to Belfast Bay. 

The great divergence of the glacial rivers, both for short and long 
distances, from the recorded movements of the ice suggest many questions 
as to the causes that determined the courses of the rivers. The subject is 
briefly treated in the following chapter. 


RELATIONS OF GLACIAL RIVERS TO RELIEF FORMS OF THE LAND. 


The general facts as to the topographical relations of the osar rivers 
have already been stated. These rivers often flowed over the lower hills, 
but not over hills higher than 200 feet except in western Maine, where many 
gravel series go over hills a little more than 200 feet, and over one hill 400 
feet, above the ground on the north. 

A question of detail arises whether the glacial streams were determined 
to the low passes before the hills adjoining the passes emerged from the 
ice, premising that it is only rarely in Maine that ridges are parallel with 
the direction of ice movement. Almost always they are transverse. 

The phenomena of delta branches proves that a single glacial river 
sometimes either used too widely diverging channels simultaneously or 
abandoned one of the channels for another. This phenomenon is very com- 
mon in southwestern Maine and over most of the State. But these delta 
branches go over no higher hills than the tributary branches or main osars, 
and they throw no light on the time the glacial rivers were established in 
the low passes. 

The hills adjoining the low passes penetrated by the glacial rivers rise 
to a height of 100 to 1,000 or more feet above the passes. If at or near 
the time that the ice melted over the transverse. hills bordering the passes, 
glacial streams crossed them, we ought under certain conditions to find 


traces of such streams. 
MON XXXIV 21. 


322 GLACIAL GRAVELS OF MAINE. 


1. If subglacial, they ought to have left channels of erosion in the till 
or deposits of glacial gravel, at least on the south sides of the hills, like the 
hillside eskers. 

2. If superficial, there would come a time when the top of the thmning 
ice did not rise so far above the hills but that the channels would cut down 
through the ice to the till. Erosion of the till would follow until the hill 
emerged from the ice. The eroded matter would be left somewhere as 
glacial gravel. Or if the surface streams disappeared down crevasses at the 
tops of the hills, they ought, while escaping as subglacial streams, to erode 
the till and leave gravels. 

3. The lowering of the ice to the top of a hill would necessarily 
deflect to some neighboring pass any stream previously crossing the hill. 
The deflection might take place in various ways. It might happen some 
miles to the north, or a pool might be formed on the north slope of the hill 
which would in fact so far check the force of the stream that it would 
deposit only scanty sediments that might since have been wholly or partly 
eroded. But we can at least conceive of a stream thus deflected leaving 
erayel terraces to mark its new channel along the northern slope of the hill 
or at some point north. One such case would be very significant. As 
elsewhere recorded, there are cases on the north sides of hills of lateral 
deflection from the general course of large glacial rivers, as at South Albion 
and in Montville and elsewhere, but no gravels on the hills marking more 
ancient channels than those in which the osars proper were deposited. 

The Greenland and Alaskan glaciers show prominent bulging on their 
surface, presumably due to passing over hidden hills. Such bulgings must 
appear while the tops of the obstacles are a considerable distance beneath 
the ice. Whenever bulging of the surface is accompanied by deep crevasses 
it would be possible for surface streams here to escape beneath the ice as 
subglacial streams, but it must often have happened that the raising of the 
ice over the hills would cause the surface water to gather in the lower parts 
of the ice surface, i. e., over the low passes of the underlying hills. How 
far such bulging over transverse hills helped establish the courses of the 
rivers through the passes is uncertain. 

Numbers of the hillside kames are situated on the south slopes of hills 
higher than 200 feet above the ground on the north. The small size of the 
gravel deposits does not call for large streams or long-continued flow. In 


SEDIMENTATION. 323 


some cases it appears probable that the local drainage of the hillside would 
furnish all the water required to deposit the gravel. But there are other 
cases (as that found near Wilton, elsewhere described) where the stream was 
of good size at the top of the hill. In such cases the streams must have 
had a gathering ground to the north. Of course such streams ceased to flow 
when the hills rose to the surface of the ice, but thus far I have found no 
traces of deflection channels into which they turned after their original 
channel was interrupted. 

Summary—Some of the streams that deposited the hillside kames appear 
to be instances of glacial streams whose career was cut short by the lower- 
ing of the ice to the tops of transverse hills. Thus far I can not identify 
them with any of the long rivers, nor trace any channels they abandoned 
for others. In the case of delta branches the glacial rivers may have 
abandoned one channel for another, but such branches obey the same law 
respecting low passes as the main rivers. In case of the larger rivers pene- 
trating low passes, there is as yet no field proof that the rivers even flowed 
anywhere except where the osars were deposited. The general inference 
follows that the courses of the great glacial rivers were determined to the 
low passes before the osars were deposited or the adjoining hills were bare 
of ice. 


SEDIMENTATION IN PLACES FAVORABLE OR UNFAVORABLE TO THE 
' FORMATION OF CREVASSES. 


The discontinuous gravel deposits found near the coast region often 
form on a lenticular hill or drumlin, as near Belfast, or on the tops of low 
hills, as near Portland. Both the Kennebee and the Penobscot rivers for 
many miles are flanked by osars, somewhat discontinuous, that are for the 
most of the distance found at the flanks of the valleys or near the top of 
the steep bank 50 to 100 feet above the rivers, just where crevasses would 
naturally form. Near Lewiston the Androscoggin River shows the same 
peculiarity for a few miles. 

On the other hand, some of the discontinuous gravels are in the bot- 
toms of valleys or on level ground where there appears to be no inequality 
of the ground to cause crevasses. So, also, the long osars love to zigzag 
over broad plains, often through swamps, where the land is very level and 
even and there is no apparent cause for crevasses. They often follow the 


324 GLACIAL GRAVELS OF MAINE. 


axis of a valley or zigzag from one side to the other m a way that shows no 
connection with the inequalities of the and. 

Thus far I have been able to make no generalization, but certainly the 
determination of the positions of the crevasses is a difficult matter, and per- 
haps often impossible. Many details in regard to particular places will be 
found in the descriptions of the gravel systems. 


GLACIAL RIVERS OF MAINE: SUMMARY. 


In the preceding pages we have spoken of the great length and volume 
of the glacial rivers of Maine as attested by the gravels they deposited. 
Care has been taken to avoid naming them either subglacial or superficial. 
From whatever point of view we look, the difficulties are immense in 
accounting for the branchings of the rivers of the ice-sheet, their directions 
and their relations to the relief forms of the land, the nature of their sedi- 
ments, etc., on the theory that we are dealing with subglacial streams alone. 
To insist that the glacial gravels are wholly due to subglacial streams, or 
wholly to superficial streams, appears to me to be dangerously like the dis- 
pute between the followers of Hutton and those of Werner as to whether 
the earth had come to its present condition by the action of water or fire. 
Both sides of that controversy were partly right and partly wrong, and 
probably this is the case in the controversy as to the glacial streams. 
Those who study the question near the great terminal moraines will every- 
where see signs of subglacial streams only. Those who study in north- 
ern New England will also see phenomena that are consistent with the 
hypothesis of superficial streams. It is too early for anyone to settle finally 
the moot question of glacial streams. In the following interpretations I 
have endeavored to correlate the facts in Maine, so far as I have observed 
them, with those of Greenland. The best interpretation will prevail. 


GLACIAL POTHOLES. 


The process of pothole making has long been well understood in the 
form in which it appears in the beds of surface streams of the land. If we 
go to some place where a rapid stream passes over a series of waterfalls 
and rapids, especially over granite rocks, we can see potholes in all stages 
of formation An accessible locality is the falls of the Androscoggin River 


GLACIAL POTHOLES. e285 


at Brunswick. Here and there the water can be seen flowing over an 
angular depression in the rock, where a portion of the granite has broken 
away under the action of frost, ice gorges, the force of the water, ete. In 
process of time the surface is sand carved and hollowed out into bowl 
shape. The water falls into the cavity, rebounds in a curve, and swiftly 
shoots up the other side. Up to this time the sand grains and stones of 
various sizes used by the stream in this process are driven almost imme- 
diately out of the cavity, along with the upward rebound of the water. 
By degrees the cavity deepens, until some day a stone falls into the bowl 
of such size that the water can not roll it up the steepened slopes. The 
stream now sets this stone to rolling, at first with considerable vertical 
motion, but more and more, as the hole deepens, the horizontal whirling 
prevails. ‘The grinding now proceeds with multiplied rapidity. 

The conditions for the formation of a pothole are the following: (1) A 
rapid stream. (2) A rock firm enough to withstand the direct impact of 
the water. Thus potholes are more frequently found in granites, sand- 
stones, and indurated slates than in schists and shales easily weathered or 
split and broken under the action of the water. (8) The formation of such 
a cavity as to permit a vortical motion of the water. (4) A moderate 
quantity of stones for the stream to whirl around in the hole. If there is 
a large quantity of sediment swept along by the stream, the cavity will 
soon be filled or partly filled with stones and the process of excavation 
will be stopped. Sooner or later most potholes are filled in this way. - 

It is important to note that the direct impact of the running water bears 
a very subordinate part in pothole erosion. The principal agency is the 
friction of the rolled stones and bowlders. It makes little difference whether 
the water falls into the cavity from above or is shot horizontally, or nearly 
so, across the mouth of the opening, provided the water is kept whirling. 

The best-known glacial potholes in Maine are situated near Riges 
Landing, on the island of Georgetown. They were examined and measured 
by me in 1879. The region has since been explored by Mr. P. C. Manning, 
of Portland, whose observations were presented in a paper read before 
the Portland Society of Natural History. He found similar potholes in 
several other of the islands situated east and southeast of Bath. Some 
of these were called to his attention by Mr. Alexander Johnston, of Wis- 
casset. Several times archeologists have asserted that these potholes were 


326 GLACIAL GRAVELS OF MAINE, 


excavated by the Indians. That they are glacial potholes is proved by the 
following facts: 

One of the potholes near Riggsville is situated about 15 miles south- 
ward from that place, on the shore of Robin Hoods Cove. The pothole is 
covered by about 1 foot of water at time of ordinary high tide. It is near 
10 feet in depth; its average diameter is 4 feet at the top and 6 feet at the 
bottom. It is excavated in a little shelf of rock on the side of a rather steep 
ledgy hill, about 40 feet high. Within a few rods this hill slopes in the 
opposite direction from the shore, down to the valley of a small brook 
which enters the cove about one-eighth of a mile north of the pothole. 
The ground slopes down from the hill in all directions, so that the only sur- 
face drainage that ever could reach this pothole must have come from a 
slope only a few rods long. The rock is a compact gneiss, with no veins 
or dikes at this place and no fault or fracture. I could find no other sign 
of running water in the vicinity. There were stones in the bottom of the 
hole that could be moved around by an oar, but I had no means of getting 
them out, and it was impossible to see more than 2 feet into the black water. 
Robin Hoods Cove is here near one-fourth of a mile wide, and contains no 
islands or rocks to cause a tidal race. About one-eighth of a mile north of 
Riggs Landing are two potholes at an elevation of about 60 feet above the 
sea. The one situated at the southwest is about 4 feet in diameter and 5 
feet deep. he other is about 6 feet in diameter and 10 feet deep. Both 
are nearly round, and the walls are quite smooth. The layers of gneiss, 
tilted up at high angle, are continuous, except where interrupted by the 
holes. The same layers can be readily traced on opposite sides of the holes. 
There is no sign of veins or fractures. In the potholes were rounded peb- 
bles and bowlders, one of them 3 feet in diameter, well rounded at the 
edges and angles. Some of the rounded stones had been taken out by 
previous explorers. The holes are situated on the southern slope of a hill 
of gneiss that rises 150 feet (by aneroid) above the sea. The hillside shows 
much bare rock and 1s broken by numerous hillocks and small valleys. We 
reach the top within about one-fourth of a mile from the shore. All the 
surface drainage that ever could have reached the holes came from this hill- 
side, and that, too, on an irregular surface where no single valley exists to. 
direct the flow of water to these holes. 

About one-half mile north of Riggs Landing there is a pothole on the 


GLACIAL POTHOLES. Bi) 7 


shore situated a foot or two above high tide. It is 2 feet in diameter and 
4 feet deep. About 4 feet west of this hole is a shallow bowl with very 
smooth inner surface, an incipient pothole. There are several masses of 
water-rounded gravel near here, which at the time of my visit I supposed 
to be esker gravel, probably deposited by the same glacial stream that 
formed the potholes. I am now uncertain whether it is.esker or beach 
gravel. 

No one familiar with potholes could fail to recognize as potholes these 
round wells with smoothly polished inner surface, even if he did not find 
within some of them the round cobbles and smoothed bowlders used in 
grinding out the cavity. All are found on short slopes. There is hardly a 
grass field in Maine that would not contain potholes if these were produced 
by land waters. The potholes are manifestly in places where no ordinary 
streams can ever have flowed, and must be due to the action of glacial 
streams. These potholes are found in a region where there is a larger 
proportion of bare rock than in any other part of the Maine coast. They 
are situated a few miles east of the Kennebee River. At the time the sea 
stood at the 225-230-foot level the whole region was deeply under water 
and exposed to the force of the Atlantic. The rocks are gneissoid and _ 
schistose, which rocks usually produced more till than is seen in this region. 
The scarcity of till is in part due to marine erosion and in part to the sub- 
glacial streams. If other regions were as bare of till as this, it is possible 
we might find glacial potholes everywhere along the coast. It is ineredi- 
ble that Indians excavated holes such as these. 

In the interior of the State the only potholes known to me are found 
in the beds of streams, with a single exception. This is situated in the 
town of Paris, about one-half mile west of Snows Falls. It was first 
pointed out to me by Mr. N. H. Perry, mineralogist, of South Paris. By 
aneroid it is 240 feet above Snows Falls. Above these falls the valley of 
the Little Androscoggin widens into a triangular basin 3 miles in diameter. 
The pothole is situated near the top of a hill lying directly south of this 
broad open valley, and if the valley were filled by a glacier the ice would 
naturally abut against this hill. From the highest point of the hill (about 
300 feet above the river) a ridge extends northeastward down the slope. 
At one place this ridge is cut across at right angles by a ravine 100 feet 
wide, bordered on each side by steep rocks rising about 20 feet. On the 


328 GLACIAL GRAVELS OF MAINE. 


northeast side of the ravine there is a narrow step or shelf situated about 
halfway between the top and the bottom of the wall. Its position is shown 
in the accompanying diagram. The hole is nearly round. It is 21 inches 
in diameter, 16 inches deep on the lower side, and 2 feet on the upper. 
The upper part of the interior is somewhat weathered and rough. The 
lower part, which is generally filled with water, is very smoothly polished. 
The bottom is almost hemispherical. The granite of the region weathers 
rough. These facts prove it to be a pothole, not a freak of weathering. 
Its situation halfway up the side of a cliff and within a few rods of the 
highest part of the ridge, whence the water flows in several different direc- 
tions, conclusively proves that it can not have been formed by any stream 
of surface drainage. A glacier moving from the north would naturally be 
broken by crevasses as it flowed over the cliff. This would be a favorable 
place for a stream flowing on the surface of the ice to plunge 
to the bottom and escape as a subglacial stream. I could 
find no glacial gravel in the vicinity. A subglacial stream 
flowing from this point southward would fall more than 200 
feet within a mile, and might be expected to sweep its chan- 
es et nel clear of sediment. If a subglacial stream from the north 
ali? and pothole; flowed up the long hill and over the cliff it probably ought 
ai to have left sediment or other sign on an up slope that rises 
at least 200 feet within a mile. The north slope of the hill is covered 
deeply with the ordinary granitic till of the region, without glacial gravel 
or erosion channel or any other sign of a glacial stream. The only admis- 
sible interpretation of these facts that occurs to me is that a superficial 
stream here tumbled down a crevasse that formed as the ice passed up 
the cliffs. 

Can potholes be formed at the foot of a moulin shaft? Professor Dana 
has suggested that the change in position of the waterfall due to the 
advance of the ice would produce an elongated rather than a round cavity. 

It is a fact that as each crevasse moves onward a new crevasse is pro- 
duced in the rear of the former, and a new well is soon excavated down 
the crevasse last formed. It will naturally result that the water will not 
continually fall in the same place, but over an area as long as the distance 
between the successive shafts. In other words, each shaft begins at a cer- 
tain place and moves on, subjecting all the rock over which it passes to the 


GLACIAL POTHOLES. 229 


direct impact of the water, until it is superseded by the next crevasse, 
which then repeats the process. But there must be an enlargement at the 
base of the shaft, varying in size according to the size of the stream, the depth 
of ice, and the amount of warmed water. This may in many cases permit 
the water to scatter, so that it will not strike the rock in a round definite 
stream. But be this as it may, the direct mechanical impact of the water 
against the rock has very little to do with eroding potholes except to start 
the process. It is chiefly the stones rolled round and round by the. water 
that do the work. Were the rock so soft that mechanical erosion by the 
water exceeded the attrition of the whirling stones, we should have, not a 
smooth-walled pothole, but a canyon of erosion with irregular surface. 
When once a cavity is found or made which is deep enough to prevent the 
stones swept along by the stream from being prematurely washed away, 
the erosion by the rolling stones would, in case of hard rocks, so far exceed 
the mechanical erosion of the water that the shape of the well would be 
that due to the attrition of the stones, with hardly a trace of direct water 
erosion. All that is needed is that the water in the pothole be kept whirl- 
ing. When a nearly vertical cascade strikes the rock, the water must shoot 
swiftly outward on all sides in nearly a horizontal plane. If a pothole 
were within reach of these out-rushing waters, the water within it would be 
kept whirling as well as if a vertical stream fell into it. Whether, then, the 
water at a glacier mill falls directly into a pothole or anywhere near it, it 
will continue to whirl the water in the hole. And the hole would be as 
round as one formed by any other stream, unless the nature of the rock 
permitted it to be easily eroded by the direct impact of the water. 

Regarding glacial potholes, my conclusions are as follows: 

1. They may be formed by subglacial streams. 

2. They may be formed at the foot of the waterfall where a superficial 
stream pours down a crevasse. 

3. They form only where the stream carries but little sediment or is 
swift enough to keep its channel clear of sediment, or nearly so. If a stream 
begins to drop its sediment an incipient pothole would soon fill up and 
ultimately would be covered by a mass of glacial gravel. 

4. The velocity of subglacial streams is so great, since they are urged 
by a great pressure from behind, that they might be able to form potholes 
at a considerable depth beneath the sea or a lake into which they might 


330 GLACIAL GRAVELS OF MAINE. 


flow. A superficial stream falling down a crevasse could also whirl the 
water at a considerable depth, if it was of large size. The glacial water- 
falls are often many hundred feet high, and the water attains a high velocity 
in falling. How deep beneath the water potholes could thus be formed is 
uncertain. In any particular case we should, in order even to guess, have 
to know the size of the streams and the thickness of ice. 

5. The existence of glacial potholes in places remote from any recog- 
nizable glacial gravels is proof that not every glacial stream left sediments. 
Only the larger masses of the drift of these streams have thus far been 
mapped. The smaller masses are buried beneath the englacial (upper) till 
or the marine clays of the coast region. So also are the potholes and ero- 
sion channels excavated by the subglacial rivers in the solid rock. I have 
not found any of the latter in Maine which are of geological importance, 
but Professor Dana showed me one of this kind near New Haven. 


FORMATION OF KAMES AND OSARS. 


Ridges, domes, and plains rising 50 to 150 feet above the surrounding 
till testify that a very large amount of work has been expended in bringing 
so great masses together. They usually rise to a greater Leight and show 
greater thickness than equal areas of till in the same regions. On the: 
average they are areas of unusual accumulation. They can not have been 
derived from the local subglacial till supplemented by the englacial till 
contained in a body of ice of such length and breadth as at the given place 
deposited an area of till equal to that covered by the gravel. A supply must 
have been brought from abroad. And since a large amount of the finer 
detritus of the till is washed away in the process of making glacial gravel, 
this foreign supply must have been large. Such local accumulations might 
be caused in various ways. 

1. In ease of the longer glacial rivers, flowing as they did up and over 
hills, we might expect areas of till erosion on steep down slopes or near the 
tops of passes, where the swift streams carried all before them, alternating 
with areas of accumulation. In places all the till, both subglacial and 
englacial, has disappeared, and often all but the coarsest of the water-rolled 
matter. In other places (as at The Notch, Garland), the osar river did not 
succeed in eroding all the till over which it flowed. This erosion of the till 
in the course of osar rivers sometimes took place along a definite channel 


1 


FORMATION OF KAMBS AND OSARS. aol 


of erosion bordered by rather steep walls (as north of Hogback Mountain, 
Montville), but more often the erosion is diffused. We see that till is absent, 
but we find no bank or margin which can be said to mark the limit reached 
by erosion. A characteristic form is shown in Pl. XXVI, 4. The discon- 
tinuous osars lie in regions so covered by marine clays that we do not know 
what forms the erosion takes. . 

2. It is evident that during the last days of the ice-sheet the englacial 
morainal matter would appear on the surface in consequence of the melting 
of the ice above it. There would form on the ice a multitude of small 
superficial streams and seeps which would carry off much of the finer part 
of the exposed till and precipitate it into the main channels. The larger of 
these lateral tributaries formed the short tributaries of the osar rivers else- 
where recorded. No matter whether the longer ridges were deposited by 
subglacial or superglacial streams, in either case there must have been a 
multitude of superficial tributaries that have left little or no gravel. ‘ Indeed, 
their work was almost wholly erosive, not constructive. Their slopes were 
probably steep. They simply carried away such of the till of the region 
they drained as they could lift, and cast it into the main river channels, 
where it either went to make up the osar-ridges or was carried into lakes or 
the sea to form a part of the glacial deltas. The larger stones over which 
these brooks flowed would be left in place and be but little polished. Being 
in the upper part of the till the signs of water wash and wear would in 
most cases long since have disappeared by weathering. The diffused ero- 
sion of the englacial till could be accounted for by the action of a multi- 
tude of these lateral streams. A diffused erosion of the subglacial till is 
more difficult to explain, unless by the wandering of the streams. 

3. The flow of the ice no doubt often helped to bring osar matter 
together. 

(a) At the end or front of moving ice. In this case the flow of the 
ice constantly brings moraine matter to the front and throws it down for 
the subglacial streams to act upon as they swiftly emerge from their 
tunnels. In such a case the sediments deposited in front of the ice 
would consist partly of worn matter transported from a distance by the 
subglacial streams (or superficial, if such there should be), and partly of 
matter which would otherwise form part of the amorphous terminal 
morame and which happened to be dropped into the streams very near 


Davy GLACIAL GRAVELS OF MAINE. 


the end of the ice. Such matter would be less rolled. Where the ice 
met the sea a marine delta would be formed in front of it. Where the 
ice front was aboye the sea, as was probably the case for a time in the 
valleys of the Carrabassett and several other streams at about the same 
distance from the coast, plains of gravel were formed in the valleys in 
front of the ice. With respect to the glacial streams and the ice front, these 
may be termed frontal deltas or overwash aprons. ‘They are the correlative 
of the sediments formed in front of all glaciers ending on the land. Such 
a series of frontal plains were found south of the great terminal moraines 
of the ice-sheet for a considerable part of their length. At the south end 
of Sebago Lake a very deep mass of glacial gravel accumulated, and, as 
elsewhere explained, ice movements probably contributed to brine this 
great mass together, although it must be admitted that glacial streams can 
transport sediments long distances. | 

(b) When the flow of a subglacial stream was transverse to that of 
the ice. The great size of the stones and bowlders contained in the grayels 
of the hilly country west of the Saco River, and other facts, favor the 
hypothesis that they were deposited in large part by subglacial streams. 
If so, the eskers must often have been deposited in such subglacial 
channels transversely to the flow of ice, for the ridges of those reticulated 
series of kames trend in every direction. In this case either (1) the ice 
pushed the channel with its contained sediments bodily forward, or (2) the 
ice flowed over the gravel, or (3) the ice was melted and eroded by the 
stream as fast as it advanced, or (4) the ice may sometimes have been 
stationary. The truth probably combines the second and third hypotheses, 
and in both cases some morainal matter would be dropped into the channel 
as the ice passed over it. 

(c) When the channel was parallel with the direction of ice flow. In 
this case it is certain that there would, especially in case of deep ice, be 
more or less flow of the ice inward from the sides. That the channel did 
not then collapse, like an unused moulin shaft, must be due to the antago- 
nistic action of the stream enlarging its channel. Some till would be con- 
tained within the ice melted and eroded as it flowed inward, and thus some 
esker matter would be brought together. 

(d) In most glaciers the swiftest flow is found near the glacial river. 
This must in part be due to the fact that the ice is there generally the 


U. S. GEOLOGICAL SURVEY MONOGRAPH XXXIV PL. XXVI 


A. BARE LEDGES IN CHANNEL OF GLACIAL RIVER; PARSONSFIELD, LOOKING SOUTHEAST. 


Most of the bowlders in sight have been water-rolled, 


B. OSAR SPRINKLED WITH TILL BOWLDERS; PROSPECT, 


Flanks of ridge partly covered with marine clay; bowlders attributed to floes of sea ice: 


BOWLDERS OF THE GLACIAL GRAVELS. Boo 


thickest; yet it is also possible that the presence of abundant subglacial 
waters facilitates the flow of ice in some degree. Both causes would pro- 
duce an oblique flow inward toward the line of swiftest motion. Such a 
movement would bring till matter to the stream, or nearer to it. 

So far as movements of the ice brought the matter of the kames and 
osars together, they distinctly resemble the medial, lateral, or terminal 
moraines of ordinary valley glaciers. Converging glacial strie are else- 
where recorded. ° 

BOWLDERS OF THE GLACIAL GRAVELS. 

When bowlders are found on the surface of masses of glacial sedi- 
ments, it is important to determine whether they have been worn and _pol- 
ished by water action. This often requires considerable excavation, since 
it is only beneath the earth, where it has been protected from the action of 
the weather, that we can expect the polished surface to have been preserved. 
Many bowlders of coarse granite have so far weathered and fallen to pieces 
since the glacial epoch that even beneath the ground it is now impossible 
to know with certainty whether they were once polished or not. Omitting, 
then, some undetermined cases, the bowlders of the glacial sediments may 
be classed as follows: 

1. Below the highest level of the sea are many bowlders not smoothed 
by running water which overlie both the fossiliferous marine clays and the 
coarser glacial sediments, also the osar border clays. They have the shapes 
and rough surfaces characteristic of bowlders of the upper (englacial) till. 
They are scattered here and there at intervals, generally one in a place, but 
sometimes, especially on the north sides of hills, in heaps and sheets. They 
are most abundant on slopes favorable to the grounding of floes of shore ice. 
The deposits are so discontinuous and helter-skelter in their distribution and 
so unlike a sheet of till in composition and structure that I attribute them 
to floes of shore ice or small bergs. Two theories suggest themselves: 
that there was a readvance of the ice over the marine clays, the ice con- 
taining but little drift, or that the bowlders tumbled down from the ice upon 
clays formed in front of the ice during its retreat before the sea. 

2. Bowlders are sometimes found in the till beneath the glacial gravel 
and projecting upward into the gravel. In some cases the parts projecting 
above the till were distinctly water-polished. This is a very common 
occurrence at the marine glacial deltas. 


334 GLACIAL GRAVELS OF MAINE. 


Instances are elsewhere recorded (see p. 161) where streams and 
springs have eroded portions of the glacial marine deltas and exposed till 
strewn with bowlders just like the ordinary till of the locality, or where 
the delta is thin the tops of the larger bowlders project above the gravel. 

3. Bowlders having rounded and polished surfaces are found within or 
partly within the glacial gravels. These must be as truly a part of the 
formation as the finer sediments. There are multitudes of them in the 
gravels of southwesterm Maine of all sizes up to 6 feet.in diameter. 

4, Elsewhere are described certain large bowlders found in the northern 
part of Baldwin. They are situated on a northern slope in the midst of 
medium sand, and have little or no water polish. The sand is horizontally 
terraced in such a way as to suggest that the bowlders were deposited by — 
floating ice in a broad osar channel which contained a lake-like body of water 
confined between the ice on the north, east, and west and the hill situated to 
the south. An alternative hypothesis is that the broad osar channels were 
overarched by ice resting upon the water that collected north of the hills. 

5. In the case of the larger ice channels, especially the superficial 
ones, floating ice would often transport stones and bowlders like any other 
river ice. I do not know how in all cases to distinguish whether a bowlder 
not polished and rounded was dropped from the ice into the bed of the 
glacial river, or was transported by floating ice, or was driven along by ice 
gorges. We know that ice dams to-day are efficient means of transporting 
large bowlders. Not many years ago in Howland an ice gorge of the 
Piscataquis River forced upward a very large bowlder 10 feet out of the 
bed of the river and left it on the silty flood plain several rods back from 
the channel of the river. The ice gorges of the osar channels must have 
been efficient means of transporting bowlders and leaving them in the 
midst of fine sediment. 

6. Bowlders not water-polished are found here and there on the surface 
of the osar border clay, i. e., the clay deposited in a very much broadened 
osar channel. These broad channels were from one-eighth to near three- 
fourths of a mile wide, and it is extremely improbable that they were 
subglacial. The few stones and bowlders they here and there contain were 
almost certainly dropped by floating ice. If arched by ice for so great a 
width, it was probably sustained by flotation on. the underlying water. 

7. There are considerable numbers of bowlders not waterworn, which 


BOWLDERS OF THE GLACIAL GRAVELS. aa 


quite certainly slid down into the channel of the glacial river from the ice 
overhead or the walls at the sides. Such are the bowlders overlying the 
osar at the south end of the Grand Lake of the St. Croix. (See p. 75.) 
In the wilderness a few miles southeast of Aurora the gravel of the great 
Katahdin osar is found in an interesting relation to a train of granite 
bowlders. The place is situated in the valley of Leighton Brook, a tribu- 
tary of the Middle Branch of the Union River. The course of the train 
is nearly north and south, and parallel with the ice flow. The train con- 
sists of bowlders piled one above another so as to make a moraine-like 
ridge 10 to 30 feet high, and some of the bowlders are 10 to 20 feet in 
diameter. The osar here forms a-broad ridge of sand, gravel, and cobbles 
transverse to the bowlder train. The train comes up to the edge of the 
osar, and several of its bowlders overlie the gravel. Near the same place 
the osar crosses another similar ridge of till, and its flanks are overlain by 
the bowlders. 

An important and difficult question arises concerning the proper inter- 
pretation of the facts as to the presence of large water-rolled bowlders as 
an integral part of the kame or osar gravel. Several facts should be noted. 

1. In many places, especially in western Maine, the large bowlders are 
more abundant in the kames and osars than in the same amount of the 
average till of the region. (See Pl. XXVII, 4.) This is due to the finer 
part of the till having been washed away, leaving the coarser residue. 

2. Almost universally the largest bowlders of the till are most abun- 
dant at the surface. In the glacial gravels the larger bowlders are as 
often, perhaps more often, contained in the lower part of the gravel. The 
two arrangements so alternate in the glacial gravels as to make the inter- 
pretation doubtful. Most of the large bowlders in the glacial gravel are 
found in the granite areas, sometimes underlying and sometimes overlying 
finer sediments. 

In this connection we must also consider what has become of the 
bowlders that were contained in the ice that was melted and eroded during 
the formation and maintenance of the channel in which the glacial sediment 
was deposited. This ice must have contained its average proportion of 
bowlders, yet over large areas only fine matter appears on the surface of 
the osars and osar-plains. As elsewhere noted, we have reason to believe 
that the osars are, on the average, areas of accumulation. With material 


336 GLACIAL GRAVELS OF MAINE. 


that may be termed indigenous—because, in order to become a part of 
the glacial gravel, it only needed to be laid bare by the melting and 
erosion of the ice around it—there is mixed much matter derived from the 
subglacial till or the adjacent regions. The indigenous matter, as it was 
released from the ice, necessarily fell into the channel and became mixed 
with the foreign drift. The details of osar transportation are very complex, 
and the interpretation in case of individual bowlders is doubtful, in view of 
the many alternative fates that might happen to any particular stone or 
bowlder. When a polished bowlder overlies finer sediment, we know the 
order of deposition, but we do not know whether the bowlder fell from the 
roof of an ice vault, or slid down from the overhanging walls of a canyon, 
or was transported to the place by moving water, or by floating ice, or by 
an ice gorge. Unfortunately the presence of large water-rolled bowlders 
does not give us a conclusive answer to the question whether they were 
transported by subglacial or superficial streams. Yet where they overlie 
finer sediments, the larger the number of such bowlders the greater is the 
probability that they weré dropped from the roof of a subglacial vault. 
This is a sufficient dynamical cause for large bowlders being lifted above 
finer sediments, and it is a constant and inevitable feature of the marginal 
part of an ice-sheet. Certainly a less number of bowlders will be con- 
tained in the ice of the overhanging walls of an open channel than in the 
whole roof of an arch. Besides, the other modes of transportation named 
are agencies that would naturally be occasional rather than constant methods 
of the glacial river. 

Summary——In case of a superficial river, the melting and erosion of the 
ice in the channel would proceed from above downward to the ground, and 
then laterally outward. The disposition of the larger bowlders of the till 
indicates that, on the average, the large bowlders were as high in the ice 
as the finer materials were, or probably higher than they were. If so, 
these large bowlders would first be laid bare in the bottom of the deepen- 
ing superficial channel. Subsequently deposited sediments would be laid 
on top of them or at their sides. The only large bowlders dropped from 
the ice into the osar channel would be from the overhanging lateral walls. 
We thus see that in case of a superficial canyon most of the bowlders of 
the upper till contained within the ice melted or eroded to form the chan- 
nel ought to be beneath the gravel. The argument is complicated by the 


U. S. GEOLOGICAL SURVEY 


MONOGRAPH XXXIV PL. XXVII 


ay E 


A. RETICULATED RIDGES OF COARSE WATER-ROLLED GRAVEL; PARSONSFIELD, LOOKING NORTH. 


Glacial river flowed through low pass in distance down the hill to the foreground. 


Lip 


Via 
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B. STRATIFICATION OF GLACIAL MARINE DELTA; MONROE. 


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BOWLDERS OF GLACIAL GRAVELS. Bol 


fact that we have no proof that the whole length of an open canyon would 
be simultaneously an area of deposition. On the contrary, the analogies 
all favor the hypothesis that as the ice retreated northward the more north- 
ern portion of superficial channels would be areas of denudation, their 
drift being swept southward and deposited nearer the margin of the ice- 
sheet. Ifso, we would have at each place the ice all melted in the bottoms 
of the channels before sediments began to be deposited, and this would 
result in all the bowlders first being freed from ice and left on the bed of 
the canyon, to be afterwards covered with finer drift. This would well 
account for the long reaches of osars and osar-plains containing few or no 
large bowlders on the surface. 

In case of a subglacial river, the enlargement proceeded from below 
upward and laterally. ‘The bowlders contained in the ice forming the roof 
of the vault would from time to time drop into the channel as it became 
enlarged and they were released from the ice. If the bowlders were high 
up in the ice, they would be last to fall. Yet if at this place the velocity 
were such as to sweep all the finer matter from the channel, these bowlders 
might be left on the bed of the subglacial stream. Then as the ice became 
thinner a time might come when fine matter would be deposited at this 
place, and now be found overlying the large bowlders. So also the local 
land slopes must be considered, i. e., whether the place of observation was 
on up or down slopes. 

Thus the large bowlders do not form a crucial test between the sub- 
glacial and superglacial streams. Yet we are warranted im affirming that 
the presence of very large quantities of fine sedimentary matter overlying 
the till bowlders is consistent with the hypothesis of a superficial stream, 
and the presence of a large number of rolled bowlders in the upper parts 
of the glacial gravels can be considered as probable evidence of a subglacial 
stream. The fewer the number of such bowlders in the one case and the 
ereater the number in the other, the greater becomes the degree of proba- 
bility. And the matter is still further complicated by the great difference 
in the size of the bowlders furnished by the different kinds of rock. In 
slate regions there might be found only one bowlder to a square rod, while 
in granite regions there might be ten or twenty. A superficial channel 
would show very different deposits in the two cases, yet they would be 


formed in the same manner; and so of a subglacial stream. 
MON XXXIV 22 


338 GLACIAL GRAVELS OF MAINE. 


REMARKS ON THE GLACIATION OF THE ROCKY MOUNTAINS. 


The glaciation of the Rocky Mountains throws some light on the 
glaciation of Maine, and therefore a few of the principal valleys are here 
briefly described. Questions pertaining to the problems of two or more 
glaciations of the mountains and the water drift of Tertiary time are 
omitted as not having a direct bearing on the questions arising in Maine. 


LA PLATA MOUNTAINS. 


These mountains are situated in southwestern Colorado (north latitude 
37° 25’), and rise above 13,000 feet. They lie to the west of the San Juan 
Mountains, and are the first high mountains encountered by the warm 
southwest winds that bring moisture from the Pacific Ocean. To the west 
and southwest lies the great plain of Arizona and southern Utah, out of 
which rise here and there volcanic peaks and ranges of hills. The precipi- 
tation in the form of snow is heavy in these mountains. Snowslides fre- 
quently rush down the lateral ravines into the main valleys in such masses 
that often they do not entirely melt during the summer, although situated 
so far south. 

The mountains consist of a mass of upheaval due to igneous eruptions 
through sedimentary beds which have been somewhat metamorphosed. 
This makes it easy to recognize matter from the mountains as compared 
with the unaltered sediments of the adjacent plains. The mass of upheaval 
has been deeply dissected by a radiating system of streams, so that the 
mountains now consist of centrally connected ridges separated by profound 
canyons ending above in rather narrow cirques, the ridges being only a few 
feet wide on their tops and having their lateral slopes steep as talus will lie, 
and often precipitous. Many of these slopes are so steep that lateral 
moraines must have slid down the mountain sides as fast as the elaciers 
melted, but here and there are broader parts of the ridges, or shelves on 
their sides, or gutter slopes, where morainal matter could lodge. 

The evidence is conclusive that these valleys were once filled by 
extensive glaciers. 

Glacial scratches —A though the local rocks resist chemical decomposition 
very well, they fracture readily. Hence, only here and there does the 
exposed rock in place preserve the glacial scratches. Many places are 
covered with a talus which shows slabs up to 4 feet in length that are well 


LA PLATA MOUNTAINS. 339 


glaciated on one side. Fresh exposures from beneath the soil reveal ela- 
ciated rock up to near the top of the secondary ridges. 

Moraines—Qn the steeper lateral slopes of the valleys there .is no 
moraine stuff. On gentler slopes there is a thin sheet or scattering of 
erratics. No distinct ridges or terraces were observed, except one on a 
shelf of the mountainside situated in the valley of the East Mancos River 
about 3 miles from its head, and 250 feet above the valley; also two at 
Helmet Peak. This peak is the highest peak of a high ridge which sepa- 
rates the East Mancos and West Mancos valleys. To the west (in lee of) 
this peak, and perhaps 50 feet below the summit, are two moraines, one 
lateral to each valley. Most of the material is rather fine and well gla- 
ciated. The upper surface of the moraines conforms to the slopes of the 
mountain, here quite gentle. These terraces are shown to be moraines, 
not only by the glaciation of the stones, but also by the fact that the 
local rock is igneous (hornblendic trachyte of Hayden) while most of the 
glaciated stones are of quartzite and other erratic material. The upper 
part of the peak is so weathered and shattered that I can not be sure 
whether it was ever glaciated or not; hence it is uncertain whether these 
moraines were pushed out laterally at the surface of the ice or were formed 
subglacially as tail to the peak as crag, at a time when the ice in the two 
valleys rose above the ridge that divides them. This is about 600 feet 
above the valley of the Kast Mancos. 

In the upper 3 miles of the valley of East Mancos River there are a 
number of small retreatal or terminal moraines in the bottom of the valley, 
which here is U-shaped, but becomes V-shaped nearer the plains. After 
entering the plains the stream flows in a valley of erosion in sedimentary 
beds. This valley grows wider and wider up to near a mile in breadth 
at Mancos. 

Lateral and terminal moraines would naturally form where the stream 
emerges from the mountains, but the slope here is very steep, and most of 
the moraine stuff appears to have become a part of the glacial gravel or 
has been left much scattered. The upper valley of La Plata River is 
considerably broader than that of the East Mancos. It contained a much 
larger glacier, which has left moraines arranged about like those of the 
valley already described. 


Glacial gravels— Large overwash or frontal aprons of water-rounded gravel, 


340 GLACIAL GRAVELS OF MAINE. 


cobbles, bowlderets, and bowlders up to 5 feet in diameter begin 2 to 4 
miles from the head of these streams and extend 15 or more miles down 
the valleys. The size of the stones grows smaller as we go below the 
principal terminal moraines. There is a large terrace in the valley of La 
Plata River a little below where it emerges from the mountains, which is 
composed in large part of very coarse matter and appears like a water- 
washed terminal moraine. The bowlders were probably rounded by the 
waves of a Tertiary lake. 

In the narrower part of the East Mancos Valley the plain of water- 
rounded matter is 50 to 150 feet wide and 3 to 8 feet deep. While the 
stones of the moraines show unequal wear into subangular forms, and some 
faces with little wear, these are polished quite equally on all sides and have 
much rounder shapes. Some parts of the valley have been worked as 
gold placers, and thus it has been revealed that underneath the gravel is 
glaciated rock, hollowed out into numerous rather shallow potholes. The 
miners affirm that most of the gold, which is quite coarse, is found in coarse 
gravel near the bed rock, and not in the bottoms of the potholes and 
hollows, but on level rock between them. This proves that the currents 
were swiftest where the potholes and basins now are. The gravels are 
most easily interpreted as due to swift subglacial streams, either beneath the 
ice or in front of the ice as they rushed from the mouths of their tunnels. 
The stream has eroded a portion of the original gravel deposit and 
rearranged a portion as a new flood-plain. 

Summary——The principal valieys of La Plata Mountains were filled by 
glaciers 600 or more feet deep. A very large proportion of the transported 
matter was acted upon by the subglacial streams, with the result that for 
many miles the valleys are strewn with frontal plains of glacial sediments, 
though mixed probably with considerable stream wash. The moraines 
are of less size than the ordinary for glaciers of such length. Hayden’s 
Atlas of Colorado shows no moraines among La Plata Mountains. My 
exploration of the mountains was confined to two valleys. 


LAS ANIMAS VALLEY. 


Las Animas River rises in the heart of the San Juan Mountains and 
flows southward into New Mexico, where it joins the San Juan River, 
which it is the principal tributary. Its head waters occupy a radiating 


LAS ANIMAS VALLEY. 341 


system of deep valleys bordered by mountains rising to elevations of from 
11,000 to 14,000 feet. Over the upper part of this valley, covering 500 
square miles, the precipitation is probably greater than over any other 
equal area in Colorado. Every cirque and lateral valley contained its 
glacier, which was tributary to that of a main valley. 

The rocks of this region are largely voleanic, and in general weather 
easily, either by chemical decomposition or by fracture. Glacial scorings 
are seldom found on exposed rock surfaces. Excavations made in con- 
structing roads over the mountain passes and to the mines show that in the 
larger cirques and passes the rock is glaciated up to about 12,000 feet. 
Mining excavations have been made at higher elevations, but none of them 
visited by me are in such situations that we could expect them to show the 
glaciated rock. Hence, while it is probable that the glaciers extended nearly 
or quite to the tops of the higher basins, I have as yet no glacial scratches 
to prove it. 

The scratches in the lateral valleys are parallel with these valleys, but 
as we descend them we come to where the scratches are parallel with the 
main valleys and transverse to the lateral. Obviously if we can determine 
the height above the main valleys that these scratches parallel with them 
reach, we shall know the depth of the great valley glaciers. Such scratches 
I have from time to time observed, and by degrees the upper limit was 
raised, till now it is proved that the main Las Animas glacier was more than 
1,000 feet. deep at Silverton and at least 1,500 feet at a point 5 miles south 
of Silverton. This was the main outlet of the ice of this region. The 
tributary glaciers reached to the tops of cols 12,000 feet high, and perhaps 
higher. Thus at Stony Pass, a pass from the Rio Grande over the Conti- 
nental Divide to Las Animas Valley via Cunningham Gulch, I found well- 
glaciated rock within 100 feet horizontally from the top of the pass, and 
on both slopes. On each side were peaks of the range rising 1,000 feet or 
more above the pass. It is thus proved that the flow took place from the 
very top of the ridge down two valleys in opposite directions. The supply 
probably came laterally from the adjacent peaks. 

Nowhere in these steep mountains have I found prominent lateral 
moraines in the form of ridges or terraces. Many of the slopes are so steep 
that no moraine stuff could remain perched on them. ‘The volcanic rocks 
have often weathered and formed slides of talus 1,000 to 2,000 feet high. 


342 GLACIAL GRAVELS OF MAINE. 


On the gentler slopes there is a body of drift that forms a complex problem. 
Near the underlying rock almost all the stones show considerable attrition, 
the original forms due to weathering and fracture having been somewhat 
changed by a subsequent process of polishing. The coarser stones are 
mixed with some fine matter, thus forming a mass somewhat resembling the 
till of New England. Approaching the surface, we find an increasing pro- 
portion of rain wash and talus. Some of the worn stones are distinctly 
glaciated. On steep slopes where there has been much sliding and soil-cap 
movement, the stones are subject to some wear, and thus the interpretation 
of the sheets of drift on the wooded slopes of these mountains is difficult. 
In many places there are bowlders in this drift that have plainly come from 
a distance; hence, in part at least, it is of glacial origin. Naturally where 
the snow covered the mountains almost to their summits there would be 
much matter borne onward in the lower part of the ice. I leave it as an 
open question how far the drift sheets of the gentler slopes of these moun- 
tains were deposited subglacially and how far they are a lateral moraine, 
left at the margin of the ice as it melted and sank to lower levels. 

The two forks of Mineral Creek come together at right angles. The 
valley of the South Fork is the larger. At a time when the ice had 
retreated from Las Animas Valley, also from the North Fork of Mineral 
Creek, a glacier still continued to flow in the valley of the South Fork. It 
flowed across the valley of the North Fork and abutted against Red Moun- 
tain, where it deposited a terminal moraine 100 feet high near the railroad 
from Silverton to Ironton. Above Silverton there are a number of terminal 
(vetreatal) moraines, more or less water-washed. All are small. 

About a mile north of the city of Durango a terminal moraine extends 
across the valley of Las Animas River, here about one-third of a mile wide. 
It forms a low ridge rising 10 to 30 feet above the sedimentary matter that 
covers its flanks. It is thus proved that at one time the ice flowed to or 
beyond Durango at an elevation of about 6,000 feet. I have not explored 
the valley below that point sufficiently to know the extreme limit of the 
ice. From Durango to Silverton it is 45 miles, and to the head of the Las 
Animas 65 to 70 miles. Assuming that the ice surface was at the top of the 
mesa near Durango and rose 1,500 feet above Silverton, we have an average 
surface gradient of about 120 feet per mile. 

From where Las Animas River emerges from the mountains it flows in 


RIO GRANDE AND SAN MIGUEL VALLEYS. 343 


a valley 1 to 2 miles wide which extends for 12 miles and then suddenly 
narrows to one-third of a mile. It is at this point that the terminal (or 
retreatal) moraine near Durango is formed. North of this point a sheet of 
water-rounded matter containing many bowlderets and bowlders extends 
for many miles up Las Animas Valley. At the melting of the ice at this 
point the moraine and overwash plain formed a barrier or dam across the 
valley, and in the broad valley to the north there gathered a shallow 
lake. Into this temporary lake there came a broad sheet of sand and silt. 
It is now practically drained by the river cutting down through the dam at 
Durango. 

The valley of Las Animas River for many miles in the mountains con- 
tains a body of water-rounded glacial gravel, now deeply eroded, so that 
in many places a little terrace here and there is all'there is left of a deposit 
once 30 to 70 feet deep. In other places, as at Silverton, this gravel plain 
is still well developed. 

It is thus proved that a glacier 1,500 or more feet deep originated in 
Las Animas Valley and flowed 70 or more miles southward. For many 
miles it was a mile or more in breadth. It left rather scanty moraines for 
a glacier of its size, but a very large amount of water-transported matter. 
Its distal extremity reaches 37° 15’ north latitude or less, an elevation 
somewhat below 6,500 feet. 

Glaciers occupied the upper valleys of Los Pinos, San Juan, Navajo, 
Chama, and other rivers of the western slopes of the San Juan Mountains, 
but I have not explored them sufficiently for notice here. 


UPPER RIO-GRANDE VALLEY. 


A very large glacier must have occupied the upper Rio Grande 
Valley. A large number of basins and valleys open down into it from the 
Continental Divide, all well glaciated. My explorations were near the 
head waters, and do not permit description of the lower end of this large 
olacier. ; 
VALLEY OF THE SAN MIGUEL RIVER. 

The main river flows in a box canyon deeply eroded in sedimentary 
rocks which are nearly horizontally bedded. Approaching the mountains, 
we find the branches occupying valleys eroded down through sheets of 
volcanic lavas and tuffs into sedimentary beds, while in the higher cirques 


344 GLACIAL GRAVELS OF MAINE. 


and valleys we find the volcanic rock alone. The mountains rise to 


heights varying from 11,000 to near 14,000 feet. They receive the first 
onset of the Pacific winds, and the precipitation is great. The valley of 
the North Fork was occupied by a glacier which left a terminal moraine 
near Keystone, about 5 miles west from Telluride. Many of the slopes are 
so steep that moraines would slide at once down to the bottoms of the 


valleys, but in many places there is a sprinkling of erratics on the sides of 


the valleys. Ophir and Trout Lake basins, on the South Fork of the San 
Miguel, each contained glaciers which left moraines in the bottoms of their 
valleys, but their gathering-grounds were small and they appear to have 
been less than 8 miles in length. ' 

The bottoms of the valleys of the San Miguel River and its three 
principal tributaries were once covered with a deep body of well-rounded 
gravel and coarser matter up to bowlders. This origimal deposit has now 
been eroded to depths of 30 to 70 feet, leaving portions of the old plain as 
terraces on the steep sides of the canyons, the so-called high bars of the 
placer miners. These terraces, growing finer by degrees, extend 40 miles 
from the mountains—how much more I do not know. They im part consist 
of Tertiary drift. In these valleys the overwash apron of glacial gravel far 
exceeded in bulk the moraines. The glacial gravel is found all the way 
from the moraines up to the mountain basins. 


VALLEY OF THE UNCOMPAHGRE RIVER. 


This stream heads against Las Animas River and flows in the oppo- 
site direction northward, and, having cut deep canyons through the Mount 
Sneffles Range, emerges from the mountains a few miles below Ouray. 
South of Ouray the very ancient quartzites are intensely glaciated, but 
retain an uneven and hummocky surface. The gentler slopes of the moun- 
tains carry sheets of drift which in composition and character resemble 
those of the upper Las Animas Valley above described. Two V-shaped 
valleys join at Ouray, below which point the valley is U-shaped and soon 
broadens to a mile or more near Ridgway, where the Dallas branch joins 
the main stream. Here a broad series of ridges and heaps of erratics 
extends obliquely across the valleys of both branches just below their junc- 
tion. Glaciers came down both valleys and left these moraines, which are 
more than a mile long and near half a mile wide, rismg in places to 150 feet 


UPPER ARKANSAS VALLEY. 345. 


im height. The moraines have been deeply cut by the river. I have not 
been able to find any moraines below Dallas, and probably these moraines 
between Ridgway and Dallas mark the extreme advance of the ice. 

The bottom of the valley from Ouray northward 40 miles to beyond 
Montrose is covered with rounded and rolled gravel and coarser matter. 
In places this overwash sheet is more than a mile wide. The fact that the 
same sort of gravel plain extends for 12 miles above the outermost moraines. 
proves that the subglacial streams during the retreat for a long time contin- 
ued to pour out glacial gravel into the open valley in front of the ice. 
Where observed this gravel is rather horizontally stratified and shows none 
of the appearance of the reticulated kame ridges. The retreat of the ice 
appears to have been rather gradual, since there are only small retreatal 
moraines in the lower parts of the valley. The sides of the main valley 
show a sprinkling of erratics, except where precipitous. 

The Uncompahgre glacier reached only 8 miles beyond the mountains,. 
but transported a very large amount of morainal matter, and also glacial 
sediments. The base of the terminal moraine at Ridgway is at 7,000 feet 
elevation. 

There were numerous glaciers in the valleys tributary to the Gunnison 
River, some of them of large size. 


UPPER ARKANSAS VALLEY. 


The glacial deposits of this valley were first described by the Hayden 
Survey, and later by Emmons in his Leadville monograph.’ It is impos- 
sible to do justice to this interesting valley without going into detail more 
than is here practicable, and only a few points will be noted. The first 
thing that attracts attention is the enormous size of the moraines which the 
glaciers that originated in the Sawatch Range have left across the main 
valley. The Arkansas Valley from Leadville southward to Salida is from 
2 to 4 miles wide between the bases of the steep mountains. The lateral 
glaciers flowing down from the mountains did not fill this broad valley—at 
least they did not for a long time during the last part of the ice period— 
and thus left moraines at the sides and in front of their valleys. Some of 
these moraines cover several square miles and are up to 1,000 feet in height. 


1Geology and Mining Industry of Leadville, with atlas, Mon. U.S. Geol. Survey, vol. 12, pp. 40-42,. 
1886. 


346 GLACIAL GRAVELS OF MAINE. 


The lateral moraines form large ridges or terraces upon the mountain sides. 
The glaciers from the west side of the valley were much larger than those 
from the east. It is possible that at one time a broad glavier occupied the 
whole Arkansas Valley, but my own observations leave the matter in doubt 
as to the last glacial period. A good place for observing these phenomena 
is in the valley of Box Creek, and its tributaries, Willow Gulch and Har- 
rington Gulch. They originate on the eastern slopes of Mount Elbert and 
flow southeastward and eastward into the Arkansas River near Hayden 
station, on the Denver and Rio Grande Railroad, about 12 miles below 
Leadville. Near here, on both sides of the Arkansas River, are well exhib- 
ited two types of valleys, the broad U-shaped valleys that were occupied 
by glaciers while their margins were being piled high with morainal and 
sedimentary drift, and the narrower valleys, generally V-shaped, due to 
recent erosion of a once continuous mass. The Arkansas River is here 
bordered by a rather level plain of glacial sediments about a mile wide. 
Extending west from this plain is the plain-like valley of Box Creek and its 
tributaries, from one-fourth mile to near a mile in width. Near the 
Arkansas they are bordered by mesas of glacial sediments ending in steep 
bluffs 150 to 250 feet high, while as we near the mountains they are bor- 
dered by bluff-like lateral moraines. These moraines prove conclusively 
that the upper portions of these valleys were filled by glaciers that origi- 
nated in the large cirques of Mount Elbert. If the glaciers had stopped at 
the base of the mountain they ought to have deposited terminal moraines. 
Instead, a U-shaped valley of the same character as those bordered by 
lateral moraines extends continuously to the Arkansas Valley, which is also 
free from moraines at this place. The conclusion follows that three glaciers 
originated on Mount Elbert and united near its base to form a single tongue, 
and it in turn united with a glacier which filled the bottom of the Arkansas 
Valley for many miles below Leadville over a varying breadth of one-half 
mile to somewhat more than a mile. This main glacier received many 
tributaries from the adjoining mountains. Between the successive lateral 
valley glaciers and the main glacier that extended along the axis of the 
Arkansas Valley there were open spaces bare of ice into which the subgla- 
cial streams of the lateral glaciers poured and deposited overwash aprons 
of glacial sediments. Sometimes these alluvial mesas end next the river 
bluffs in sand or fie clay and rock flour, proving that here were glacial 


UPPER ARKANSAS VALLEY. 347 


lakes. In other places coarse gravel continues right up to the bluff mark- 
ing the former margin of the Arkansas glacier, proving that the waters that 
were poured from above into these open spaces found ready exit into the 
subglacial waterways of the main glacier, and in such cases the alluvial 
mesa was formed subaerially, ending in a steep bluff because piled against 
the side of the Arkansas glacier. The symmetry of the U-shaped valleys 
bordered by bluffs of glacial sediments or moraines is better preserved in 
case of the shorter glaciers. The enormous amount of morainal matter 
brought down by the longer lateral glaciers formed dams that obstructed 
their flow and forced them to wander in search of an outlet. On the great 
moraines of the Lake Creek glacier, which are situated northeast of Twin 
Lakes, and which formed in part the lateral moraine of the Willow Gulch 
glacier of Mount Elbert, we find remarkably sudden transitions between 
morainal ridges and glacial sediments. The region has been prospected by 
placer miners, and thus were revealed the following facts: At the top of the 
great moraine a shaft was dug 98 feet in gritty clay. The digging is on a 
small level place. Two hundred feet west a steep ridge rises perhaps 50 
feet above this flat and is composed of bowlders and other coarse moraine 
stuff. In several places are mounds or small mesas that rise 50 to 100 
feet above the rest of the moraine, which are proved by tunnels and shafts 
to be composed of clay and fine sand. These local masses of fine sedi- 
ments in the midst of moraimes were probably deposited in small glacial 
lakes like those of the marginal region of the Malespina glacier, described 
by Russell. The retreat of the Mount Elbert glaciers here described seems 
to have been quite rapid until we reach the base of the mountain. Here 
the principal tributary, the Willow Gulch glacier, formed several frontal 
alluvial terraces at different elevations. Going up the mountain from this 
place we find only a few small deposits of glacial gravel, the streams of 
the shortening glacier becoming too feeble to transport much sediment. 
But the shrinking of the glacier is marked by a series of retreatal moraines 
that are found every half mile or so up to timber line. Near the base of 
the mountain the morainal matter is nearly all well glaciated, and often 
contains so much rock flour, clay, and fine débris as to resemble the till of 
New England. Going up the mountain we find the glaciation becoming 
less intense, till at the last we find rock piles in the characteristic form of 
moraines with few signs of attrition. This delineation is only intended to 


348 GLACIAL GRAVELS OF MAINE. 


describe the last part of the last glacial period. Larlier the lateral glaciers 
may have been confluent in an ice-sheet which covered all the Arkansas 
Valley from mountain to mountain. 

We also here have the same alluvial aprons we find in the San Juan 
valleys. Not being confined in a narrow valley, they take the characteris- 
tic form of the alluvial cone radiating from the terminal moraines. The 
aprons are somewhat distinct as far south as Buena Vista; then they merge 
into a plain of coarse water-rounded matter that occupies the valley to a 
point beyond Pueblo, except where it has disappeared owing to erosion. 
Some of this water-rolled matter came from the Wet Mountains and the 
Sangre de Christo Range, but most of it came down the main Arkansas 
River. 

The general law of frontal aprons of glacial gravel is that they become 
finer as we go away from the principal terminal moraines. From the mouth 
of Lake Creek to near Buena Vista there are multitudes of water-rounded 
bowlders in the plain of rolled matter that here covers the eastern part of 
the Arkansas Valley. Many of them are from 6 to 10 feet in diameter. 
Of course it is not meant to assert that they were not glaciated before 
being worn by the action of water. Below this point the material becomes 
finer. 

Emmons has described the so-called ‘‘ Lake beds” at Leadville. I 
have discovered there were local glacial lakes not far from Twin Lakes and » 
at other points in the valley. They formed between the tongues of ice 
that then projected into the valleys and formed dams across it extending to 
the main valley glacier. 

PIKES PEAK RANGE. 

Glaciers formed in the valleys of some of the branches of West Beaver 
Creek that were 3 to 4 miles in length; also in the deep canyon-like valley 
that extends north from the peak, but I have not explored the latter system- 
atically. A glacier formed on the south slopes of Pikes Peak in the valley 
of Hast Beaver Creek. Its terminal moraines form the dams that confine 
the Seven Lakes. The morainal matter is itself somewhat sandy and 
water-washed, but the valley below here contains no overwash apron of 
glacial gravel. Probably there was some rather fine sediment, but it has 
now disappeared by erosion on a steep slope. The length of this glacier 
was not far from 3 miles. . 


UPPER ARKANSAS VALLEY. 349 


Lake Moraine is situated in a valley descending from the col between 
Pikes Peak and Bald Mountain. A glacier but little more than a mile in 
length occupied this basin. It left prominent lateral moraines near 200 feet 
above the bottom of the basin, and formed a massive terminal moraine near 
one-fourth of a mile long and 100 or more feet deep. There is a depres- 
sion across the terminal moraine, in which a stream flows. No glacial 
gravel appears in the valley below, which is very steep, so that the over- 
wash of the glacier would soon be eroded. In the bottom of the depres- 
sion in the terminal moraine appears a mass of fine sediment, mixed with 
occasional bowlders, which, under the microscope, is seen to consist of glacial 
rock flour. 

This little glacier was situated between 10,000 and 11,000 feet eleva- 
tion. The snowfall of this range is much less than that of the Continental 
Divide. The temperature was low even in summer. ‘The glacial waters 
flowed so sluggishly that even much of the rock flour did not get beyond 
the terminal moraine. 

A little glacier formed on the east side of Pikes Peak and formed a 
diminutive moraine which now holds in a lakelet. 


SOUTH PARK. 


A number of glaciers originated in the Mosquito Range and flowed 
eastward into the South Park. Some of them were near 10 miles in length. 
They left moderate-sized moraines and plains of glacial gravel that extend 
15 miles down into the open park. These plains are marked ‘scattered 
drift” on Hayden’s maps. In most cases where I have had opportunity to 
examine a region thus marked they end in the mountains in a glaciated 
region and are frontal plains of glacial sediments. The proportion of 
glacial gravel to moraines is here probably greater than in the Arkansas 


Valley. 


ROARING FORK. 


The valley of the Middle Branch of the Roaring Fork contained a 
glacier 15 or more miles in length. The moraines of this glacier can be 
seen from the Colorado Midland Railway. Laie Ivanhoe, along this rail- 
way, is held in by a morainal dam. Below the terminal moraines the 
valley was left covered with a deep sheet of water-rolled sediments which 
hhas now been eroded to a depth of 30 or more feet. 


350. GLACIAL GRAVELS OF MAINE. 


The valleys tributary to the South Branch of the Roarmg Fork were 
occupied by glaciers to a point not far below Aspen. They left moderate- 
sized moraines and a sheet of glacial gravel that extends for 30 or more 
miles down the yalley. In the valley of Hunters Creek, east of Aspen, a 
line of perched bowlders marks the upper limit of the ice. 


ROCK CREEK. 


This stream flows for a few miles west, and then north, and drains the 
western slopes of the Elk Mountains. Glaciers extended 12 miles down 
the valley and have left numerous rather small moraines. The amount of 
glacial gravel in the valley is less than in most valleys of the western slope 
having so large a drainage surface. 

When one follows the Roaring Fork down to its junction with the 
Eagle River to form the Grand River, and thence down to the Colorado, he 
will appreciate what a tremendous weapon the glaciers furnished the present 
rivers. The plains of rolled gravel and cobbles left by the glaciers have 
helped protect the higher slopes of the mountains from erosion, but the 
streams have rolled them down to the Gulf of California with fatal ettect 
on the plains and plateaus. In time of high water the ceaseless rattle and 
roar of those stones as the Grand River surges them on is one of the most 
astonishing phendmena of the mountain slopes. If the ear be held. near 
the water or against a boat, one hears a roar as of distant thunder mingled 
with the sharper click of near-by stones. After that the profound canyons 
of the plateau region are no mystery. 


ESTES PARK. 


Several glaciers 5 to 10 miles long flowed down into Estes Park. 
They left very large lateral moraines near where they enter the park, and 
smaller terminal moraines at about 6,100 feet elevation. The retreat of 
the ice is marked by a series of terminal moraines, which are found at 
intervals all the way up to the ultimate basins in which the glaciers origi- 
nated. Nowhere have I seen such great masses of bowlders showing few 
or no signs of glaciation and without admixture of fine material, as some 
of these retreated moraines exhibit. They are locally known as bowlder 
fields, and are often almost impassable even to men on foot, owing to the 
large size of the bowlders. They are mostly of granite and are more 


VALLEY OF SALMON RIVER. oo 1 


(J) 


angular than ordinary bowlders of decomposition. The proportion of 
glacial gravel to morainal matter is smaller than in any other glaciers of 
the same size that I have found in Colorado. 

In the higher cirques of this region there are numerous fields of per- 
petual snow. One of these in a valley lying on the northeast slopes of 
Hague’s Peak is consolidated to ice and exhibits transverse crevasses. Itis 
plainly sliding, if not flowing, down the mountain side. It appears so 
much like a true glacier that I have named it the Hallett glacier, after the 
discoverer. 

VALLEY OF THE SALMON RIVER, IDAHO. 

Many local glaciers originated in the Bitterroot Mountains and flowed 
down into the valleys of the Salmon River and its tributaries. The Lemhi 
Valley for many miles above Salmon City is several miles wide. It is a 
valley of erosion in sedimentary fresh-water lake beds. In the bottom of 
the valley is an extensive plain of rounded gravel and cobbles, while on the 
tops of mesas 200 to 300 feet higher is a thin sheet of similar material. 
This higher gravel may be due to a more ancient glaciation than the last, 
or it may have been formed on the margin of a great confluent glacier that 
filled the whole valley. It is probable that some or all of these are beach 
pebbles of the old lake. 

West of Salmon City lies the Salmon River Range of mountains. 
They rise rather steeply from the valleys of Salmon River and its trib- 
utaries up to an altitude of 6,000 to 9,000 feet. The main range lies nearly 
north and south, and there are several spurs reaching out to the west and 
northwest. The rocks are very ancient quartzites, slates, and schists with 
intervening and bordering areas of coarser granites and a few extrusions of 
rather recent acidic volcanic rocks. The original masses of upheaval have 
been dissected into many valleys and basins, and show plainly the marks 
of geological old age. The mountains are well exposed to moist winds 
from the Pacific Ocean, and the precipitation is large. 

Napius Creek drains a large area on the western slopes of these 
mountains and flows into Big Creek, itself a tributary of Salmon River. I 
have had opportunity to partially explore the upper 20 miles of this valley, 
extending 7 miles west from the old mining camp of Leesburg to the 
so-called Falls of Napius Creek. Here the stream cuts through a high 
ridge of granite, and thence descends by a series of rapids and cascades to 


352 GLACIAL GRAVELS OF MAINE. 


Big Creek. Numerous lateral valleys extend from the main creek from 5 
to 10 miles into the mountains. The area of this part of the valley is 
about 300 square miles. The elevation of the Falls of Napius (or Bull of 
the Woods) is about 5,700 feet. Lying east of this poimt is an area of 
several square miles of voleanic rock, then a crescent of schists and quartz- 
ites, and around that a crooked belt of granites. This makes it easy to dis- 
tinguish local from transported matter. 

The lateral valleys and cirques were once filled by glaciers which 


united in the main valley to form a large glacier or ice-sheet that rose 


above the hills adjoining the main creek so as to extend back for a mile or 
more into the lateral valleys. This is proved by the following facts: 

The quartzites resist chemical decay, but readily fracture. The 
voleanie rocks, granites, and schists yield to both fracture and chemical 
action. Hence the exposed rock has seldom preserved its glacial scratches. 
Fresh exposures reveal glaciated rock in various places in the valley. 


MORAINES. 


Moraines of four kinds were observed. 

Lateral moraines— The slopes of the hills next to the main valleys are 
strewn with a scattering of erratic material, but no distinct or prominent 
ridges or terraces were found. 

Terminal moraines —A bout 2 miles east of the Falls of Napius is a moraine 
on the north side of the creek beginning near the stream and extending at 
nearly a right angle to the creek northward up to an elevation of about 800 
feet above the creek. It forms a series of low ridges with some outlying 
spurs. The mountainside on which it lies rises pretty steeply from the 
stream. The great depth of the ice at this point makes it certain that the 
glacier extended far beyond the region explored; hence this is a retreatal 
moraine. The moraine corresponding to this on the south side of the creek 
has disappeared near the stream on a very steep slope. ‘There are several 
other small terminal or retreatal moraines above this at intervals in the 
valley. 

Crag and taii— The high granite ridge which extends northeastward from 
the Falls of Napius shows no erratics till we reach a point three-fourths of a 
mile north from the creek. Here on a broader part of the ridge is a moraine 
consisting of well-glaciated stones with a few bowlders. It forms a sheet 


VALLEY OF SALMON RIVER. 353 


that caps the ridge and is only 200 or 300 feet wide and a short fourth of a 
mile long. It formed in lee of a small peak of volcanic rock that projects 
about 30 feet above the side of the little peak, and a few glaciated stones 
are also found on the other two sides of the crag, but none on its top. 
Perhaps a better name for this arrangement would be “erage and collar.” 
This is about 500 feet above Napius Creek. 

Crag and cap—A out 3 miles east of the last-named locality and 1 mile 
south of Napius Creek is an oblong-conical hill rising about 800 feet above 
the creek. The top of the hill is capped by a ridge of glaciated matter and 
erratics. ‘The local rock is a dark schist entirely unlike the morainal mat- 
ter. The ridge is hardly one-eighth of a mile long and 250 feet wide, with 
steep lateral slopes. It contains many granite bowlders from 10 up to 20 
feet in diameter. 

I noticed several other moraines capping hills at different elevations. 
These moraines are separated by large areas that show little or no foreign 
matter. We have not a sheet of till, like that which covers New England, 
but local masses here aad there. The situations of these high moraines 
described as crag and collar and crag and cap appear to be similar to the 
moraines now forming at the nunatakker of the Greenland ice-sheet. They 
probably formed when the hills rose near or above the surface of the ice. 
It is doubtful whether this drift was transported subglacially or supergla- 
cially, or both. The large areas bare of transported matter favor the 
hypothesis of much of surface transportation; the intense glaciation of 


. 
* 


much of the morainal matter favors the subglacial hypothesis. 


= GLACIAL GRAVELS. 


One of the most noticeable features of this valley is the large sheet of 
waterworn gravel, cobbles, and bowlderets, with some bowlders, which once 
filled the bottom of the main valley and thence extended up the lateral val- 
leys for several miles. The stream has eroded the old plain to depths of 30 
to 70 feet, the uneroded portions forming terraces, known to placer miners 
as bars. As we go back from the stream the gravel slopes upward 100 or 
more feet per mile. Excavations for placer mining show that under the 
gravel lies well-glaciated rock in place. ‘The gravel plain is 2 miles wide 
a short distance west from Leesburg. Mixed with much waterworn matter 


are some stones bearing glacial scratches. The proportion of this sort of 
MON XXXIV 23 


354 GLACIAL GRAVELS OF MAINE. 


stones increases as we go back from the main creek. Some of these enlarge- 
ments of the gravel plain may have been deposited in glacial lakes caused 
by some of the lateral glaciers flowing across the main valley and damming 
it. I nowhere found, however, anything that resembles the reticulated 
kames, though there are here, as in numerous places in the Arkansas Val- 
ley, low swells or ridges obliquely transverse to the course of the glaciers 
showing one slope of the cross section shorter and steeper than the other. 
In all cases the distal slope is the steeper. A large amount of water-rounded 
matter is found in the valleys below the region visited. _ 


SUMMARY. 


An ice-sheet covered the bottom of the valley of Napius Creek and 
rose above the hills near the river. Higher in the mountains the hills sepa- 
rating the lateral valleys probably rose above the snow; they certainly rose 
far above the confluent glacier of the main valley. This ice-sheet formed 
“nunatak” moraines at various points, but no continuous sheet of till) The 
proportion of water-rolled as compared with morainal matter is very large. 
This seems to indicate that this gravel plain was formed in front of the ice 
‘during the final melting. The much-rolled matter was poured out by the 
subglacial streams in front of the ice, and the morainal matter that was on 
or in the ice fell into the water at the ice front, and thus received too little 
waterwear to efface the glacial scratches. The gravels poured out during 
the time of maximum depth of ice are beyond the field explored. 


GENERAL SUMMARY OF THE ROCKY MOUNTAIN REGION. 


The above-recorded observations cover nearly 10 degrees of latitude, 
though most of them were made in the State of Colorado. 

Several characteristics of the glaciation of the mountain region deserve 
attention. 

1. All writers are agreed that the mountain glaciers were confined to 
single drainage basins. We find the nearest approach to ice-sheets in the 
larger valleys, where the tributaries united to form glaciers that rose above 
the low hills and ridges nearest the main valleys. 

2. In general the moraines formed at the ends or margims of the 
glaciers, not subglacially, with a residue of cases where the interpretation 


is doubtful. 


GLACIPRS OF ALASKA. a) 


3. All the larger glaciers formed extensive overwash aprons or sheets 
of water-rolled material, which are coarser in composition at the principal 
terminal moraines and become finer as we go down the valleys below them. 
This glacial gravel was deposited in diminishing quantities as we go 
upward from the outer terminal moraines. The retreatal terminal moraines 
extend higher up the valleys than the water-rolled matter, and often we 
find above the last gravel deposit a number of retreatal moraines scattered 
over a space of a mile or two. Almost every valley in the mountains 
attests that the small glaciers that marked the final disappearance of the 
ice formed but little glacial sediment, and what there is shows only a lim- 
ited amount of waterwear. 

4. The glacial gravel is deposited in rather level or even plains or 
terraces, sometimes rising one above another as we go back into the moun- 
tains. No ordinary kames or osars are found, though the low ridges 
transverse to the course of the glacier above noted are in some degree a 
correlative deposit to the retreatal moraines and “kames” observed by 
Wright near the Muir glacier. They are an eighth of a mile broad, and 
the interpretation is doubtful. They are well developed in a small valley 
3 miles north of Twin Lakes in the Arkansas Valley. In several places, 
such, for instance, as the valley of the Arkansas 12 miles south of Lead- 
ville, on the east side of the river, there is a jumble of heaps and ridges of 
glacial gravel, but this is due to unequal erosion of a once continuous sheet. ’ 

The sheets of glacial gravel of the Rocky Mountain glaciers are rather 
horizontally stratified and in their surface features resemble the broad osars 
or osar terraces of Maine. They are the equivalents of the deposits I have 
termed “frontal deltas” in Maine. But whereas in the mountains the finer 
clay and sand was at once swept away by the rapid streams, except locally 
in glacial lakes, in Maine the slopes were so gentle that they form broad 
sheets of silts and clays widely covering the valleys all the way to the sea- 
shore of that time. 

GLACIERS OF ALASKA. 


The origin of frontal or overwash aprons of glacial gravel, also of 
kames such as are formed by valley glaciers, is illustrated by the Mount 
St. Elias glaciers described by Prof. Israel C. Russell.t The Malaspina 


‘Nat. Geog. Mag., vol. 3, pp. 53-204; also Am. Jour. Sci., 3d series, vol. 43, pp. 169-182, March, 1892. 


356 GLACIAL GRAVELS OF MAINE. 


glacier approaches the character of a local ice-sheet, and more nearly illus- 
trates the conditions of the ice-sheet in Maine than of ordinary Alpine or 
valley glaciers. Over large areas it is nearly stagnant. During the decay 
of the ice-sheet in Maine there must have been many places where the ice 
was in nearly the same condition, the forward flow being arrested by high 
transverse hills in front, while often the supply from the névé was also 
obstructed by still higher hills 10 to 30 miles farther north. 


Some of the formations illustrated by the observations of Professor 


Russell are the foilowing: 
OVERWASH APRONS. 


Along the southern margin of the Malaspina glacier, between the Yahtse and 
Point Manby, there are hundreds of streams which pour out of the escarpment formed 
by the border of the glacier or rise like great fountains from the gravel and bowlders 
at its base. All of these streams are brown and heavy with sediment and overloaded 
with bowlders and stones. * * * Themost interesting of these is Fountain Stream. 
This comes to the surface in one great spring fully 100 feet across. The water rises 
under such pressure that it is thrown 12 or 15 feet into the air, and sends up jets of 
spray 6 or 8 feet higher. It then rolls seaward, forming a broad, swift river which 
divides and spreads out in many channels both to the right and left and has inundated 
several hundred acres of forest land with gravel and sand.! 


This admirably illustrates the formation of the large sheets of over- 
wash gravels that extend outward from the terminal moraines of the upper 
Arkansas Valley and many other valleys in the mountain region. In 
Maine we have a nearly correlative deposit in the plain of coarse gravel 
that extends across the Carrabassett Valley near East New Portland and 
North New Portland, and in several other valleys, as elsewhere described, 
especially in the valley of the Androscoggin River in Bethel and Gilead, 
Maine, and extending into Shelburne and Gorham, New Hampshire. 


OSAR STREAMS AND OSARS. 


The principal streams on the eastern margin in 1891 were the Osar, Kame, and 
Kwik. Hach of these issues from a tunnel and then flows for some distance between 
walls of ice. Of the three streams mentioned the most interesting is the Kame. 
This issues from the mouth of a tunnel in the ice about 3 miles back from the 
actual border of the glacier, and flows for half a mile in a narrow canyon with walls 
of dirty ice 50 feet or more high. The canyon then expands and forms a valley 
bordered by moraine-covered hills of ice, which gradually widens toward the east 
until it merges with a low marshy tract bordering the shore of the bay. Well-rounded 


OSAR STREAMS AND OSARS IN ALASKA. 357 


sand and gravel is being deposited by this stream in large quantities. This covers 
the ice over which the stream flows, and during former stages was deposited in 
terraces along the lower portion of the channel. ‘These terraces, in part, at least, rest 
onice. The rounded and worn condition of the gravel and sand brought out of the 
tunnel is proof that it has had a long interglacial or subglacial journey. 

On the north side of the open channel of Kame Stream there is a sharp ridge of 
well-rounded gravel which runs parallel with the present river, and in places can be 
seen to rest on an icy bed. This was evidently deposited by a stream similar to the 
present one, but which flowed fully 100 feet higher. This ridge of gravel seems to 
be of the same general character as the kames of New England and other glaciated 
regions. * * * The formation of osars seems fully explained by the subglacial 
drainage of the Malaspina ice-sheet.’ 


In two important conditions the Malaspina ice-sheet or Piedmont 
glacier varies from the ice-sheet of Maine. 1. In Maine the morainal 
matter was basal, i. e., contained in the lower part of the ice and taken 
into the ice from below, while the drift of the Malaspina glacier is on its 
surface (marginal) or scattered through it to’ a great height—the result 
of avalanches bringing down fragments of rock and depositing them in 
successive layers on the névés of the glaciers. 2. The Mount St. Elias 
glaciers are bordered by considerable land bare of ice, and a large amount 
of water warmed above 32° flows onto the glaciers and helps to form and | 
enlarge the subglacial channels. The amount of heat thus transferred to 
points beneath the ice is very much greater than that carried by superficial 
waters of the ice surface pouring down crevasses. In Maine the hills are 
so low that in only a few of the most mountainous regions would the con- 
ditions at all approach those of Alaska. Over most of the State the glacier 
would be reduced to only 200 or 500 feet in thickness before any of the 
land would rise above the surface of the ice. In the upper Kennebec 
Valley there are a few high gravel terraces that may have been formed by 
streams flowing in the depression that forms at the margin of a glacier next 
a mountainside, but such gravels are rare. I have nowhere yet found in 
Maine the delta terraces of such marginal lakes as Professor Russell finds 
so abundantly in Alaska. he short hillside osars were formed by streams 
that flowed down steep southern slopes. They often expand into deltas at 
the bottoms of the hills, but there is no series of terraces marking successive 
levels of the water, except in the courses of the great osar rivers. These 
were fed by glacial waters, not by waters of the land bare of ice. 


1Am. Jour. Sci., 3d series, vol. 43, p. 180. 


358 GLACIAL GRAVELS OF MAINE. 


It should also be noted that the extreme stagnation of the Malaspina 
glacier must favor the solidification of the lower ice and the other causes, 
whatever they are, for the subglacial streams rising onto the surface of the 
ice. In cases of rapid glaciers flowing into the sea the subglacial streams 
are discharged into the sea and do not rise to the surface of the ice some 
miles back from the seas, as is the case of this interesting glacier. 

The ridge described above as found on the ice would probably lose its 
stratification during the melting of the subjacent ice and in structure 
resemble Indian Ridge at Andover, Massachusetts, rather than the ordinary 
stratified osar. 


OE PLB IR Wat. 


CLASSIFICATION OF THE GLACIAL SEDIMENTS OF MAINE. 


PRELIMINARY REMARKS. 


NAMES. 


A complete classification of the glacial sediments will not be possible 
till the facts of all the glaciated countries are correlated. The masses of 
glacial gravel have everywhere received local names, the ones in most 
common use by geologists being the Scotch name kame, the Irish esker, and 
the Swedish osar. At first geologists employed these terms as promiscu- 
ously as they are employed in popular usage. Later an attempt has been 
made at a classification founded on genesis. In a recent letter Professor 
Chamberlin has set forth his views on this subject as follows: 


When these gravel accumulations arranged themselves in transverse irregular 
belts and represent marginal action, especially where associated with thrusting action 
on the part of the ice, they should be distinguished from the longitudinal gravel 
ridges which represent the internal drainage system of the ice and whose development 
is quite largely dependent on a stagnant or slow-moving condition of the ice in its last 
stages. 

With the first class is associated the name ‘‘kame,” with the second the 
name ‘‘osar.” 

As between the terms ‘“‘osar” and “esker,” the first, as I understand it, 
has right of priority. The finest known example of the longer gravel ridges 
is found in Sweden, the next is that of Maine. According to published 
descriptions the gravels of Maine are more like those of Sweden than of 
Ireland. Certainly the grandest gravel system of all ought to receive 
recognition in our nomenclature. I retain the term “‘osar” for the longitu- 
dinal gravel system, and shall for the present employ the word “esker” as a 
general term applicable to any mass or ridge of glacial gravel irrespective 


of genetic classification. Thus, if a series of separated deposits be known 
359 


360 GLACIAL GRAVELS OF MAINE. 


as a discontinuous osar, we need some term to apply to the separate 
mounds and ridges, and for such purposes I employ the word ‘‘esker.” 

The gravel masses have various external features, such as continuity 
or discontinuity, narrowness of ridge with arched cross section or breadth 
with horizontal cross section, reticulations, etc., which have to be described 
by the use of various modifying terms. 

It is often a doubtful question how far local usages of language ought 
to be followed by geologists. For instance, the word “plain” is in very 
common use in Maine to denote rather level or gently rolling tracts of gla- 
cial gravel and sands, generally with some definitive, such as “Norway 
plains” (meaning tracts of reticulated kames overgrown with yellow or 
‘Norway pines”), ‘““checkerberry plains,” “blueberry plains,” “Litchfield 
Plain.” In all these cases popular usage has recognized that these “plains” 
are tracts of sand or gravel differing in composition from the soils of the 
surrounding regions; and since they are much more level than the hills, 
they come to be known as “plains,” even though they as little deserve the 
title ‘‘plains” as do the Great Plains west of the Missouri River. It is 
doubtful if geologists can go to Maine and inquire their way to many of 
the localities and deposits described in this report without employing the 
word ‘‘plains” in their inquiries. While it may be conceded that in strict 
geological language it is desirable to use the word “plain” only where it 
has a natural geometrical application, yet there are disadvantages in cutting 
entirely loose from local usage. 

On reflection, instead of the term ‘‘osar-plain” for the broad osar, the 
term ‘‘osar terrace” will often be used, partly because the term ‘‘moraine 
terrace” was used many years ago by Prof. C. H. Hitchcock’ to distinguish 
reticulated masses of glacial gravel. 


GLACIAL GRAVELS AS MODIFIED BY THE SEA. 


I assume that all the outer coast of Maine below the contour of 225 
feet, perhaps below that of 230 feet, was under the sea during the last part 
of the Glacial period. In the interior of the State the sea must have stood 
at a somewhat greater height in the principal river valleys, then deep bays. 

In general the glacial gravels that were under the sea at any time are 
somewhat different in external form from those situated above the former 


‘Preliminary Report upon the Natural History and Geology of the State of Maine, p. 270, 1861. 


SHORT ISOLATED OSARS OR ESKERS. 361 


sea level. The lenticular and broadly arched types prevail. The lateral 
slopes are usually quite gentle. In many cases the waves washed over the 
tops of the kames and osars, eroding a portion of the upper parts of the 
ridges and molding their external forms near to that of the sand bar of the 
coast. or some time I supposed that all the gravels that had been beneath 
the ocean had been thus acted upon. Later I have discovered mounds 
showing the same features in valleys that were occupied by long narrow 
straits and inlets, yet so protected from marine erosion that their change 
in form from this cause must have been small. Thus the north-and-south 
valley of Georges River was at one time a strait extending from the Bel- 
fast Bay of that period. For 10 or more miles it was only from one-fourth 
mile to near a mile wide. On the east were the high hills of Hope, Cam- 
den, and Lincolnville, and a high ridge lay on the west. The strait was 
well landlocked and protected from the outside waves. The gravel cones, 
domes, and short ridges of this valley are more or less covered by marine 
clay and have the same outline that is common elsewhere in the region that 
was under the sea, and there are no gravels washed down upon the adjacent 
clays. The same is true of the discontinuous system in the Medomae Val- 
ley above Waldoboro. While, then, it is certain that in exposed situations, 
as on the tops of the hills at Portland, the tops of the gravels were more or 
less eroded and molded by the sea, yet we must conclude that in addition 
to this effect there was a difference in the average forms of deposition ot 
the gravels of the coast and those of the interior. The former are less 
steep and approach the flowing outlines of the drumlins. 

Divided into classes according to their external features, the glacial 
sediments are as follows: 


SHORT ISOLATED OSARS OR ESKERS. 


These are perhaps the simplest form of the glacial gravels. The term 
“isolated” is applied to them because no other gravels are known to be near 
them in such relations that their formation can be attributed to the same 
glacial stream. They have the form of a cone, a dome, or often a short 
ridge, or sometimes several short ridges having a linear arrangement (length- 
wise of the ridges), or occasionally a few somewhat parallel ridges inclosing 
basins. They vary in length from a few feet up to a mile or two. A dis- 
tinguishing feature of the class is that they have no fan-shaped or enlarged 


362 GLACIAL GRAVELS OF MAINE. 


delta showing assortment of material from coarse on one side (next the 
ridge) to very fine on the other, the stratification also becoming more and 
more horizontal. Yet the material of the ridges often shows some horizontal 
gradation, the finer sediment being situated at the south. The assortment 
is not so complete when the deposit consists of ridges as where it expands 
into a broad, flat plain. Near the coast the isolated eskers mostly take the 
form of cones, domes, or short lenticular ridges. In the imterior they are 
almost always short ridges, which the lumbermen report as ‘“horsebacks.” 
North of the region of the long osars they are the only form of glacial 
gravel reported by the State geologists of Maine or others, or discovered 
by me. Thus I have note of quite a number of short ridges in the valley 
of the Masardis or St. Croix River, which flows north into the Aroostook 
River. It is possible that these are part of a connected series, but I can not 
prove it. Lumbermen report great numbers of horsebacks in the region 
drained by the St. John River, but many of these are elongated drumlins— 
at least farther south I have found many of the horsebacks to be such. 
What were the conditions under which the isolated osars or eskers were 
formed? <A good type is found about a mile south of New Vineyard Post- 
Office. The esker is situated in the jaws of a north-and-south pass through 
the high hills. It is about 10 feet high and 150 feet long. In the pass 
is a divide where the drainage waters part, some flowing north toward 
New Portland, others south to Farmington. The ridge is situated on the 
northern slope about one-fourth of a mile north of the divide. There is a 
considerable amount of alluvium south of this divide all the way to Farm- 
ington, and it is probable that it is some form of glacial sediments or frontal 
matter, but this I have not proved. To the north of the esker broad open 
valleys extend all the way to Kingfield and Mount Bigelow. In late glacial 
time the ice would naturally linger in these valleys after the ice south of 
the divide was all melted, since a supply could readily come from the 
region of high hills near the Dead River. After the front of this tongue of 
ice had retreated north of the divide a small lake would be formed south 
of the ice, confined between the ice and the hill or divide lying south of it. 
The slopes are gentle, and this lake would not be more than 15 or perhaps 
20 feet deep at the time when the extremity of the ice had receded as far 
north as the position of the ridge. The lake would nowhere be more than 
one-eighth of a mile wide. If a glacial stream poured into the supposed lake, 


oe 


SHORT ISOLATED OSARS OR ESKERS. 363 


it would spread out its sediments to form a delta. There is some fine 
alluvium in the valley, but it is not in the form of an expansion of the 
esker. The place is so near the top of the divide that there has been but 
little erosion. The fact that we find a gravel ridge without a delta in a place 
so favorable to the formation of a delta indicates that the ridge was deposited 
within the ice walls before the ice had receded as far north as the esker, and 
betore the formation of the lake, in which probably at a later period was 
deposited the fine alluvium of the valley near the kame. 

At one of the small isolated eskers we have distinct evidence of a 
glacial stream for a short distance. Several questions naturally arise as to 
whence the waters came and whither they went, as to the work they had 
done before coming to the place of the esker, and what became of the finer 
mud and clay which they must have carried away with them. There are 
several alternative hypotheses. 

1. A sediment-laden superficial stream here plunged down a crevasse. 
The coarser sediment was deposited in the enlargement, cave, or pool within 
the ice that naturally formed near the base of the waterfall. The water then 
escaped through a subglacial tunnel, carrying the finer matter with it. 

2. The esker collected in an enlargement or pool in the bottom of the 
channel of a superficial stream. Such an enlargement may have been 
begun as a pothole or pool in the ice at the base of a rapid or waterfall 
over ice or where lateral tributaries poured into the main channel. 

3. The esker may have been formed in the tunnel of a subglacial 
stream. In such a case we must account for the waters being checked for 
a part of the course of the stream, while above and below the water flowed 
so swiftly that it left little or no sediment in its tunnel, or else we must 
postulate some obstacle greater than elsewhere to the passage of the trans- 
ported matter. Such an obstacle could be furnished by the stream crossing 
an up slope. We sometimes find isolated eskers in such positions, but also 
often on down slopes where change in angle of bed can not have checked 
the sediment. Such an obstacle might also be formed by a bowlder or mass 
of ice fallen from the roof of the tunnel. 

The velocity of the water could be locally checked by an upward 
slope of the bottom of the channel, provided the tunnel was not full of 
water, but, as above noted, we often can not invoke change of slope to 
account for local deposition. Another way for checking the velocity would 


364 GLACIAL GRAVELS OF MAINE. 


be by enlarging the channel. Such enlargements must constantly be 
forming where superficial streams bring warmed waters and pour them 
down a crevasse into the glacial river. 

Here are a number of physical causes capable of doing the required 
work, and perhaps no two of the kames were formed in exactly the 
same way. 

I have many times examined the country adjacent to the isolated 
eskers for signs of glacial streams beyond the limit of the gravels them- 
selves. Thus far I have found no ravine of erosion in the till or glacial 
potholes, either north or south of these eskers. They begin and end 
abruptly, and beyond them we pass into regions covered by ordinary till. 
But it may fairly be urged that the channels of subglacial streams, being 
underneath the ice, are now covered by the upper or englacial till, while in 
the region that was beneath the sea we have the search further embarrassed 
by the deep sheets of marine clays which cover almost all that part of the 
State. Indeed, it would be possible for a ridge to end in a fan-shaped delta 
and yet be so covered by the clay that only the top of the highest part of 
the ridge appeared. 

The problem of the short isolated osars in the region that was under 
the sea is so nearly related to that of the discontinuous osars that it will be 
further discussed in connection with that class of gravels. Above the 
former level of the sea, and especially in the northern part of the State, 
the first and third of the above-mentioned hypotheses appear to me to be 
more probable than the second. Yet where the material is quite fine the 
second method may also have been employed. It is not necessary to 
premise that all the eskers were formed in the same manner. 

These eskers are situated where no ordinary stream of land drainage 
could have deposited’ them. There is no way of accounting for them 
except that they were deposited between solid walls that have now disap- 
peared, and ice is the only admissible solid with that property. The ice- 
bere theory of the drift has no adequate explanation of them. 


HILLSIDE OSARS OR ESKERS. 


The only deposits of this class of which I have note are found in a 
broad belt extending northeastwardly across the State. Its southern bor- 
der lies about 50 miles from the coast, and its breadth is perhaps 75 miles. 


HILESIDE OSARS OR ESKERS. 365 


The region is hilly. I have noted about fifty of these eskers, and doubtless 
there are many more. 

At their northern extremities a large proportion of the hillside systems 
begin at the southern brow of broad flattish-topped hills 100 to 400 feet 
high; others begin at various distances down the southern slopes of the hills. 
The hillsides fall southward or southeastward. I have discovered no ridges 
of this class on the northern slopes of hills, nor developed on the tops of 
the hills and plateaus. These eskers all end at the south in the valleys 
lying at the southern bases of the hills in which they are found. All expand 
somewhat at their southern extremities, some into a larger ridge, some into 
a small plexus of reticulated ridges inclosing basins, some into a fan-shaped 
or oval delta. Beyond the limits of this terminal enlargement I have not 
been able to trace glacial sediments, though in some cases the terminal 
deltas merge into the alluvium of the valleys in which they he in such a 
way as to indicate that the alluvium is kame or overwash matter with 
respect to the ice and the glacial stream. ‘These ridges meander somewhat, 
yet on the average diverge but little from the lines of steepest slope of the 
land surface. Owing to the outlook of the hills, this direction is nearly the 
same as that of ice flow, and also must be about the same as the direction 
of the slope of the ice surface in late glacial time. The hillside eskers vary 
in height from 5 feet or less to 20 feet, and in length from a short eighth of 
a mile to nearly 2 miles. The sediment composing them is usually gravel 
and sand, but in some cases there are cobbles, bowlderets, and even a few 
bowlders, all distinctly but not very much worn and rounded by water. 

The position of the terminal enlargement and delta, their situations 
on the southern slopes of hills, and many other considerations prove con- 
clusively that the flow of the streams that deposited the hillside systems 
was southward. If on the slopes of moderately steep hills the velocity of 
the waters that deposited the gravels was so gentle as to permit the 
deposition of sediment, such as sand and gravel, we may be certain that 
the conditions would be still more favorable to deposition on the northern 
slopes and the tops of the hills. On the contrary, no water sediments are 
found there, nothing but the usual till, and no ravines of erosion. If the 
streams which deposited these kames were subglacial in that part of their 
courses lying north of the kames, they there had a very gentle current, not 
capable of eroding the till or transporting sediments up the hills. 


366 GLACIAL GRAVELS OF MAINE. 


Again, if the hillside osars were due to local deposition in the channel 
of a long north-and-south glacial river, we ought to find similar gravels 
forming a system or connected series along the course of the hypothetical 
glacial river. But with a few exceptions the eskers of this class can not be 
brought into any kind of linear arrangement with other eskers or osars. 
In most cases hills higher than 200 feet lie to the south of these eskers, 
sometimes within a mile or two, sometimes 10 or 20 miles away. The 
great rivers that have left their gravels for a hundred miles could not flow 
over hills more than about 200 feet high. No reason can be assigned why 
streams that have left gravels for less than 2 miles should be able to flow 
‘over any higher hills, or, if so, why they have not left gravels to mark 
their channels. 

All the facts poimt to the conclusion that the hillside eskers were 
deposited very late in the Ice period. They are found in regions abounding 
in rather high hills lying transverse to the direction of glacial movement. 
These hills stopped the motion as a whole after the depth of ice came to be 
less than about 500 feet, though local movements would continue along 
north-and-south valleys like that of the Kennebec. So, too, there would be a 
limited flow from north to south between the successive ranges of transverse 
hills, especially on the southern slopes of the hills: There would still be a 
surface gradient of the ice, since in general the melting was most rapid toward 
the south and the thickness of the ice had originally increased northward. 

Some of the hillside ridges begin on the slopes of long hills and have 
1 or 2 miles of hill north of them. In such cases it is possible that the 
osar streams were wholly supplied by melting ice and other drainage of 
the hill itself. But generally these ridges begin at or near the tops of the 
southern slopes of the hills, where the supply of local drainage would be 
very small. Yet the streams had considerable volume at the north, as, for 
instance, the esker near Wilton. Such streams plainly derived their waters 
in great part from the regions lying to the northward. 

The best interpretation of the facts seems to be as follows: The ice front 
had retreated to near the point of the formation of the streams, but the ice 
north of the hills was still high enough to enable its drainage waters to flow 
southward over the hills. The absence of erosion channels or glacial sedi- 
ments on the tops and northern slopes of the hills can be accounted for on 
the following suppositions: 

1. That superficial streams flowed over the hills from the north. 


HILLSIDE OSARS OR ESKERS. 367 


2. That subglacial streams flowed up and over the hills. North of all 
hills there is always a portion of a subglacial stream tunnel where the water 
is in equilibrium to the top of the hill and flows only as it is urged by 
water from behind rising above the top of the hill. If the tunnel were 
rather large for the supply of water, the flow up the hill might be so slow 
that it would not erode channels in the ground moraine and the only gla- 
cial sediments would be deposited in the valley to the northward. I have 
found no such sediments as yet. Or the streams may have been too small 
to transport noticeable masses of gravels. 

Superficial streams flowing from the north might at or near the tops 
and southern brows of the hills pour down the crevasses that would natu- 
rally form there and escape down the slopes as subglacial streams, or they 
might continue in superficial channels, in which, after they had cut down 
to the bottom of the ice, the gravels were deposited. But all observation 
proves that on these steep hill slopes the ice would almost certainly be 
deeply shattered by crevasses, and hence it is extremely unlikely that the 
channels were superficial on the hillsides. The esker or kame, elsewhere 
described in Jay, contains so large bowlderets and bowlders that it becomes 
probable that this kame was deposited in subglacial vaults. The plexus of 
reticulated ridges can be accounted for on either the theory of subglacial 
or superglacial streams. Where the terminal enlargement takes the form 
of a horizontally stratified delta, the stream evidently escaped into a pool 
within the ice, or where the delta spreads out in the valley and passes by 
degrees into the valley drift, the stream passed beyond the ice into the open 
valley. In this case it is doubtful if the delta furnished the evidence neces- 
sary to decide definitely the question of the nature of the streams. 

The hillside eskers were perhaps not all deposited in the same manner. 
They are in situations so favorable to the production of crevasses that it 
would appear to be inevitable that a part, if not all, were formed by 
streams which, no matter what was their history toward the north, escaped 
down the hills as subglacial streams. On this hypothesis the shortness of 
the ridges would be accounted for partly by the fact that the water would 
cease to flow from the north as soon as the melting had progressed so that 
the hills emerged from the ice. Some of these kames seem to prove that 
the flow continued long enough to permit the formation of subglacial tun- 
nels in places where there had been none until the ice became quite 
thin. ‘These subglacial channels were not prolonged far. 


368 GLACIAL GRAVELS OF MAINE. 


The formation of reticulated ridges as a part of hillside eskers will be 
considered later. 

These short kames or eskers are not so impressive as the long osars, 
but they are equally strong testimony to the existence of glacier ice, and 
they possess the essential parts of the longest osar—a ridge and often a 
terminal delta. 


ISOLATED KAMES OR SHORT ESKERS ENDING IN MARINE DELTAS. 


These are confined to the country lying below the former level of the 
sea. Litchfield Plain is a type of this sort of deposit. On the north and 
northwest are a series of broad ridges somewhat reticulated and inclosing 
a lakelet and some shallower kettleholes. The material of this part of the 
plain consists of gravel, cobbles, and bowlderets, all well rounded and 
polished by water. The slopes of the ridges are not very steep. Passing 
south and southeast, we find the-ridges becoming confluent and merging 
into a rather level terrace or plain. The material at the same time becomes 
finer, and soon passes by horizontal gradations into sand, some of which 
may have been blown. The plain is situated in the midst of a rather level 
region at an elevation of about 150 feet. The Kennebee Bay of that 
time sent out an arm westward and covered the Cobbosseecontee Valley to 
Readfield. The salt water over Litchfield Plain would then be 75 or more 
feet deep. The country lying south and east of the plain is deeply covered 
by a silty marine clay. I was unable to determine whether the sand of 
the plain passes into this clay by horizontal transition. In places this 
appeared to be the case; i other places the junction was quite abrupt and 
there was reason to suspect blown sand. The plain is about a half mile in 
diameter. 

At Litchfield Plain streams capable of transporting bowlderets 15 to 
18 inches in diameter were so checked within the distance of half a mile 
that they could no longer carry even their fine sand. This gradual check- 
ing of a swift stream can be wrought only by its flowing into a body of 
comparatively still water. Two low passes lead from the plain, one north- 
ward the other northwestward, and two glacial rivers may have converged 
to this spot. If at a point so far north of the present coast these streams 
had flowed into a glacial lake, there would probably have been a series of 
similar deposits extending southward toward the sea. I have been able to 


ISOLATED OSAR-MOUNDS OR MASSIVES. 369 


find no other gravel deposit for 10 miles south of it, and the nearest on the 
north is in the northern part of Litchfield, nearly 5 miles away. The great 
thickness of the marine clay in the vicinity and its somewhat sandy or silty 
character testify that one and perhaps two glacial streams here flowed into 
the sea at a time when the ice front had retreated to this point. To the 
northwest of the plain is a rather steep terrace in the till, which may be 
due to the erosion of the ground moraine. If so, this would be more 
probably performed by a subglacial than by a superficial stream. The 
rapid slowing of the water after entering the sea proves that the streams 
were not large. The great swiftness of a small stream required in order to 
transport so large bowlderets would be more probably attained by a sub- 
glacial stream under pressure in its tunnel by the water behind it. 

Elsewhere are described two short eskers or kames in Amherst (see 
pp- 117-118) which at the south converge into a small plain of horizontally 
stratified matter showing clearly a horizontal transition of the gravel into 
They are at the foot of a hill sloping south, and were in places favorable 
for crevasses. They are, in fact, hillside kames situated below 230 feet. 

The class of kames or eskers under discussion are here termed isolated 
because no other gravels can be proved to have been deposited by the same 
glacial streams to which these are due. The field evidence rather favors 
the hypothesis that they were deposited by subglacial streams. Besides, 
we have the general consideration that near the ice front crevasses could 
sand and finally into marine clay, all within about one-fourth of a mile: 
freely form and conditions would be favorable to the formation of sub- 
glacial channels. 


ISOLATED OSAR-MOUNDS OR MASSIVES NOT ENDING IN MARINE 
DELTAS PROPER. 


These deposits, being very broad, are massives or mesas rather than 
ridges. They belong to the region below former sea level. One of these 
plains is found about 2 miles northwest of Freeport Village. It is solid 
and rather level on the top, somewhat uneven of surface, but with no reticu- 
lated ridges or kettleholes proper. The smoothness of surface may be in 
part due to the waves of the sea sweeping over it, since it occupies a posi- 
tion where it would be much exposed to the waves of the broad bay which 
then covered the valley of Royal River to the scuth of it. Judging from 

MON XXXIV——24 


370 GLACIAL GRAVELS OF MAINE. 


the surface appearances at a few small excavations, the table-land consists 
of sand, gravel, and cobbles mixed in alternating layers, but the northern 
and southern parts of the plain do not vary much in degree of fineness. 
The transition between the somewhat lenticular mass of gravel and the 
marine clay is quite abrupt, proving that they were not formed simultane- 
ously. Whereas in the delta deposited in the open sea the coarse sediments 
are stratigraphically continuous with the marine clays, one passing into the 
other by insensible degrees, in the case of the plain under consideration 
the glacial currents were, within the area of deposition, not checked suffi- 
ciently to cause them to drop their clay and silt. The gravel is overlain by 
the clay, but they are plainly of different origin and dates. Such a mass 
as this must have been deposited in a gradually enlarging pool or lake 
within the ice. The inflowing stream did not flow into a body of water as 
large as the whole plain. I conceive that it first flowed into a small pool, 
which it partially filled with sand, gravel, and cobbles. Subsequently, as 
the ice was melted and eroded, the water of the glacial stream continued to 
flow in the space between the enlarging central mass of gravel and the 
receding ice. Thus the flow was never checked, as it would have been if 
it flowed into a lake as large as this one finally became. This sort of 
structure is substantially the same as that of many of the massive plains 
that make the discontinuous systems of osars and the discontinuous portions 
of the osars. The more important features of the class are their solidity 
(freedom from kettleholes and reticulations) and their coarseness of mate- 
rial, which is in marked contrast with the horizontal passage into the finest 
sediment characteristic of the true delta. The top is somewhat convex, but 
not always conspicuously lenticular. They are found in a part of the State 
where subglacial streams abounded. They could be accounted for as being 
formed in the pool where a superficial stream fell down a crevasse, or where 
a subglacial stream entered a pool or lake within the ice. We know that a 
superficial stream can make such a pool. In case of a subglacial stream, it 
is more difficult to account for the pool. It is possible that a subglacial 
river of fresh water pouring into the sea, or having its channel obstructed 
for any other reason, would under some conditions be forced to rise up the 
crevasses, and when the ice became thin enough it could outflow upon the 
ice, or such a rise of water could be caused by a gorge in the tunnel. This 
water, now being exposed to the sun, would become warmed; and if so, 


GLACIAL MARINE DELTAS. 371 


would in time form the pool. The problem is closely connected with the 
general subject of the discontinuous osars, and will be referred to again 


later. 
GLACIAL MARINE DELTAS. 


Before proceeding to the discussion of the discontinuous osars it will 
be of advantage to consider the general characteristics of the delta-plains 
deposited by glacial rivers in the sea. They are here named “glacial marine 
deltas.” (See Pl. XXVII, B, opposite p. 336.) They were of two kinds. 

I. Those deposited in front of the ice in the open sea. This class 
spread outward in rounded or irregular fan shape when deposited over 
broad and rather level plains where they were free to expand in all direc- 
tions. In narrow valleys their shapes were necessarily determined in part 
by the adjacent hills. They conspicuously show the characteristic hori- 
zontal transition of sediments from coarse at the north to finer toward the 
south—that is, away from the mouth of the glacial river. The surface 
slopes gradually downward and outward radially to the outer edge of the 
delta, but in tidal waters this slope is much more gradual than on the land. 
The sand of the delta passes by insensible gradations into silt and silty 
clay, which in turn merges into fine fossiliferous clay. In the region of 
transition between the sand and clay the two deposits have the same sur- 
face level. Thus the proof is conclusive that they are contemporaneous 
and that the clay is a continuation of the coarser parts of the delta. But 
while logically and genetically the clay is part of the delta, yet since the 
sediments of the glacial streams are so much more largely composed of 
sand, gravel, and larger stones and bowlders, I here include under the 
term ‘‘deltas” only that portion composed of coarser matter. Moreover, the 
clayey parts of the deltas are so mixed with clay derived from wave 
erosion of the till, also with the clay brought down by the swollen rivers 
of land drainage at the close of the Glacial period, that it is difficult to 
distinguish the glacial from the other clays. So also the delta clays, being | 
scattered up and down the coast, often blend with one another, and the 
separate deltas are indistinguishable. It is noticeable that the clays are 
thicker near the mouths of the glacial rivers, and doubtless the spirit level 
will sometimes reveal where the mouths of the rivers were in cases where 
to the unassisted eye the deltas are confluent. In mapping the marine 
deltas it has been a matter of difficulty to determine where sand ends and 


372 GLACIAL GRAVELS OF MAINE, 


clay begins. The only way to secure accuracy is by micrometric measure- 
ments of the size of the grains. 

An interesting marine delta is in the valley of the west branch of the 
Union River, in Aurora. It is locally known as the Silsby Plains, and is 
elsewhere described. The valley of Union River was at one time occupied 
by an arm of the sea from 1 to 8 miles broad. Into this inlet the great 
Katahdin osar river for a time poured nearly at right angles. <A delta of 
gravel and sand formed in front of its mouth. This delta extended across 
the whole breadth of the valley then under the sea, and for 4 miles south- 
ward and nearly a mile north of the mouth of the glacial river. The last- 
named fact indicates strong tidal currents on the coast of Maine at that time. 
If the Bay of Fundy was at this time’a strait connecting the Gulf of Maine 
with the Gulf of St. Lawrence, the tides would probably not be so high in 
eastern Maine as now; yet here is evidence of considerable tidal action. 
Tidal currents sweeping along the coast would tend to mix the clay portions 
of the deltas of the glacial rivers. 

II. Another class are here termed ‘‘ice-bordered” or ‘‘narrow marine” 
deltas. They are usually much longer from north to south than from east 
to west, having but little of the fan shape. At their southern ends they pass 
by degrees into clays having the same level, like the delta-plains above 
deseribed. They are found in valleys or level regions much broader than 
they are, where there is no topographical reason why a delta, if deposited 
in the open sea, should not have spread outward in fan shape. Except at 
the southern extremity, the sand and gravel end abruptly. The east and 
west flanks commonly form a steep bank or bluff risme sometimes as much 
as 20 feet above the marine clay which here covers the base of the gravel 
plain. The transition from the coarse matter of the plain, such as sand, 
gravel, cobbles, ete., to the clay at the sides of the plain is very abrupt. 
Very evidently the clay was deposited later than the coarse matter at all 
points of the plain except on the south. iHvidently the glacial rivers flowed 
in channels which were open toward the ocean, but at the sides were bor- 
dered by ice which covered the rest of the valleys and prevented the delta 
from spreading out into fan shape. At one time I described these deltas as 
being formed in bays within the ice, into which the tidal waters extended 
as they do into an estuary. They are all situated below the contour of 230 
feet, and if they were deposited at the time the sea stood at its highest level 


GLACIAL MARINE DELTAS. By ((3) 


these broad channels in which the narrow deltas were deposited would 
indeed be estuaries. On further reflection I find they can also be accounted 
for as having been deposited in broad ice channels at a time when the sea 
stood not at its highest elevation but at the level of the delta itself, or per- 
haps at the place of transition from gravel to sand. The ice front then 
stood at or near the place of transition from sand to clay, where the clay 
of the local delta merges in the general sheet that covers all the coast. On 
this conception we have in the narrow deltas a type of the sediments 
poured into the sea or formed at or near sea level during a rise of the sea 
accompanied by melting of the ice as it advanced. If so, we could expect, 
on sloping shores, and where the flow of the glacial stream continued 
marine, a delta to extend backward from the outer one, up to the level of 
230 feet. Such a recession would show finer sediments overlying the earlier 
and coarser ones, since at any given point the water would be growing 
deeper and the distance to the shore greater as the sea rose to its highest 
level. It is doubtful if the facts thus far observed make it possible to 
decide positively between the two hypotheses, and indeed narrow marine 
deltas may have been formed in both of these ways. On either hypothesis 
the delta as we go southward was bordered laterally by ice until we reach 
the place where the delta clay merges into the broader clay sheet of the 
coast. As the ice retreated and the delta channel broadened, clay was laid 
down over the valleys at the sides of the original ice-bordered delta. The 
currents would naturally be swifter in front of the main channel. For this 
or some other reason the later-deposited clay was thin or lacking on top of 
the sand-and-gravel portions of these as well as on the broad or fan-shaped 
deltas. 

That the clay into which the marine delta-plains pass by insensible 
gradations is a true marine sediment is evidenced by the following facts: 

1. The clay extends continuously from the delta-plains to the present 
seacoast, a distance of 10 to 30 miles, and in a few cases even a greater 
distance. 

2. This clay thus is continuous with the clay that surrounds the beach 
gravels. We can not separate them. 

3. In many places this clay contains marine fossils. Near the belt of 
transition between the glacial delta sands and the clays I have not been 
able to find fossils, but within 2 or 3 miles south from that point fossils 


374. GLACIAL GRAVELS OF MAINE. 


have been found in digging wells. The nearest I have found fossils to a 
large marine delta is about 4 miles.’ 

4. The deltas here described are all found below the elevation of about 
230 feet, except those situated farthest northwest, which may have a higher 
elevation. Up to these levels the beaches are distinctly and incontestibly 
to be found. 

5. This clay covers the whole of the State up to that elevation—that 
is, all the broader valleys and such places as would not form projecting 
headlands of the expanded sea. 

6. The sand and gravel portions of adjacent marie deltas are often 
confluent or nearly so, proving that they were deposited in the same body 
of water. In York and Cumberland counties there is a succession of 
practically confluent delta-plains for about 40 miles. 

Marine delta-plains form part of both the osars—the broad osars and 


the discontinuous osars—and they form the usual termination of the great 
plains of reticulated kames. The Katahdin system expands into two deltas 
deposited in the open sea: first, in the level region west and northwest 
of Deblois; second, in the valley of Union River in Aurora. It also 
expands into a delta in Greenfield, 30 miles farther north, but I am some- 
what in doubt whether the last named is a glacial marine or a lacustrine 
delta. In like manner most of the longer gravel systems show from one to 
three marine deltas at different distances from the coast. These must mark 
either the retreat of the ice northward or an increase of elevation of the 
sea, or both causes combined. 

One fact regarding the deltas here denominated ‘‘glacial marme” 
deserves special notice. By far the largest of the delta-plams are found 
between 170 and 250 feet above the present sea level. The high level deltas 
cover hundreds of square miles. They prove that the time of most active 
transportation of glacial sediments coincided with the time when the open 
sea covered ull or nearly all the coast region of the State below the contour 
‘of 230 feet. They are so extensive and unmistakable in character, and 
all along the coast have so nearly the same relative development at 
that contour that they form an important part of the evidence as to the 


1A leaf of sea-lettuce ( Ulva lactuca) found in the upper clays at Lewiston. The lower layers of 
the clays are richly fossiliferous at Lewiston. The marine delta was situated not far north and east 
sof Lake Auburn. ; 


GLACIAL MARINE DELTAS. 375 


highest level of the sea in the coast region. Marine clays and these 
so-called marine deltas are found at all elevations up to about 230 feet near 
the coast, but the deltas have their maximum development as we approach 
that contour. Aboye that elevation the deltas are few and rather small, 
and are situated in the interior valleys. They are found at no prevailing 
elevation, and they are local, not confluent like the great deltas found at 
230 feet or not far above and below. The locality before named in York 
and Cumberland counties is the best place for the study of the confluent 
marine deltas. ‘To the careful observer in the southern parts of the State 
the contrasts between the surface deposits and characteristic scenery above 
the level of about 230 feet and those below that level is very great. In 
passing from one of these regions to the other we find a change such as in 
human affairs would be termed a revolution. The contrast is greater near 
the mouths of the great glacial rivers than away from them. It should be 
noted in this connection that the opinion is elsewhere expressed that the sea 
stood at higher levels 50 or more miles from the present coast than along 
the outer coast itself. 

In the above discussion it is assumed that the broad rounded or fan- 
shaped deltas were deposited in the open sea. It is a possible hypothesis 
that they, as well as the narrow marine deltas, were formed subglacially, in 
places where the subglacial channels had enlarged themselves laterally as 
they entered the sea, so that broad portions of the ice were undermined and 
floated on the sea water. This would make the ice approach the condition 
of glaciers which flow into a warm sea, where they are melted from beneath. 

1. The Waldoboro and other short peripheral moraines prove that the 
lower portions of the ice contained much morainal matter, though we do not 
know how great a height it attamed. “Unless the supposed broad subglacial 
river should melt all the part of the ice containing morainal matter, there 
would still remain till in the ice above the channel. As the undermelted ice 
fell off in icebergs, more or less of this débris would fall upon the under- 
lying gravel and sand. The delta-plains are covered by no sheet of till, 
though, like the marine clays and all the rest of the country below 230 feet, 
they are strewn with occasional bowlders, which I attribute to ice floes. 

2. The supposed caves beneath the ice must have been of mammoth size 
More than a score of the deltas contain a surface of more than 5 square 
miles each, and several of them contain two or three times that area. 


376 GLACIAL GRAVELS OF MAINE. 


3. The deltas of different streams are sometimes confluent. This tact 
still more enlarges the continuous areas of supposed floating ice. 

4. Unless the till were, in New England, confined to the very bottom 
of the ice, the till contained in the ice above the limit of supposed melting 
would greatly increase the specific gravity of the floating ice. It is not 
proved that till-containing ice could be sustained by flotation in so shallow 
water. Out in the Gulf of Maine at a great depth the buoyancy of the 
purer upper ice would enable a thick sheet of till-bearing ice to float. But 
the largest of the glacial marine deltas are situated near the contour of 230 
feet, where the water would be less than 100 feet deev. Only a thin sheet 
of pure ice could float under these circumstances. 

5. In the case of the Silsby Plains in Aurora, mentioned above, we 
have proof of tidal action, and most of the deltas spread outward so rapidly 
as to indicate the cooperation of the tides in the work of strewing the 
sediment of the glacial rivers up and down their valleys and along the coast 
and out to sea. Tidal currents in the open sea would do this work. It is 
uncertain what would be the action of the tides on the sediments beneath 
floating ice, since the free space beneath the ice‘would change with the 
state of the tide and the thickness of ice. 

6. The rise and fall of the tides would cause a strain on the central 
parts of the supposed undermelted ice such that from time to time small 
bergs would break off and float away to sea. Thus, even if the bottom 
ice were melted over so large areas the upper ice would soon disappear and 
the supposed cave would become a part of the open sea. 

The difficulties of the hypothesis of large areas of undermelted ice 
are so great that the hypothesis that the marine deltas were laid down over 
the bottom of the open sea I consider by far the best interpretation, though 
the margins of the ice channels would be undermelted, just as they were 
on the land. 

SYSTEMS OF DISCONTINUOUS OSARS. 

In this class a number of short ridges, often plain-like, have a linear 
arrangement and other relations such that they are regarded as having been 
deposited by the same glacial river. These systems have nearly the same 
general directions as the continuous osars, and their topographical relations 
are substantially the same. The osars as they approach the coast become 
discontinuous, like the systems now to be described. In the case of the 


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SYSTEMS OF DISCONTINUOUS OSARS., 377 


osars there can be no doubt of the action of a single glacial river, even 
when the ridge becomes interrupted. The feature of noncontinuity can 
not, therefore, in itself be urged as proving the action of more than a single 
stream. Genetic connection is to be proved or disproved by general con- 
siderations, the nature of which has been referred to elsewhere. 

The feature of systematic noncontinuity is almost wholly confined to 
the coast region. The longer osars and osar-plains frequently extend 10 to 
30 miles south of the contour of 230 feet before they become discontinuous, 
but the discontinuous character rarely extends north of that contour, and 
then usually in a modified form approaching the osar type (e. g., at North 
Monmouth). 

In the noncontinuous systems the gravel deposits are from a few feet 
up to 3 miles long, and they are separated by intervals varying within the 
same limits. The intervals between the successive deposits are a constant 
and distinguishing feature of the class. The intervals are due to the original 
manner of deposition. Ridges formed by the unequal erosion of a contin- 
uous plain are not entitled to the same name as ridges that were originally 
formed in substantially the same shapes they have at present. For this 
reason the terms “kame” or ‘‘osar” are not in this report applied to ridges 
consisting of portions of the valley drift or other alluvial plains which have 
been left as ridges simply because the surrounding matter has been eroded. 
The gravel masses under discussion have sometimes been eroded, but the 
erosion can readily be traced, and it can be asserted with greatest confi- 
dence that no continuous mass of gravel ever connected them. This is 
the more certain because they are mostly situated in the region that was 
under the sea and the gravels are wholly or partly covered by marine clay, 
which would protect them from erosion. Any agency which would erode 
the gravels must first erode the overlying clay. But in most places the 
clay still remains or has only partially been eroded. In some cases ridges 
which appear to be discontinuous may really be connected by a low ridge 
now covered from sight by the clay. But in many places streams flow 
across the space between the apparently separate deposits of the same 
system, and in their banks no gravels are seen, though they cut down to the 
till or even to the underlying rock. 

Any satisfactory explanation of the discontinuous osars must account 
not only for the deposition of the gravels but also for the intervals between 


378 GLACIAL GRAVELS OF MAINE. 


the gravels. Here arise special difficulties. The gravels afford much posi- 
tive evidence regarding themselves, but in accounting for the gaps in these 
systems we have to rely largely on negative evidence. Probably no other 
problem connected with the glacial gravels is so difficult of solution. It 
will be seen that a discussion of the origin of the gaps in the discontinuous 
systems will apply almost equally to the discontinuous portions of the osars 
and broad osars. - Indeed, if the streams which deposited the discontinuous 
kames had been longer, so as to extend farther north, nearer the névé, I 
believe that toward their northern extremities the separate ridges would be 
confluent and not distinguishable from the osars and broad osar terraces. 

The deposits forming the noncontinuous osars are of several quite dis- 
tinct types. 

1. Marine deltas. The general characteristics of these plains have 
already been described. ‘The longer of the systems under discussion almost 
always expand into one or two marine deltas; some of the shorter systems 
also contain deltas, but more of them have none. The deltas are found at 
intervals of several miles. Thus far I have not been able to find terminal 
moraines genetically connected with the marine deltas, though there is 
much reason to suspect this relation at the Waldoboro moraine; yet I have 
often suspected their existence beneath the marine clays. These clays are 
sometimes 80 to 100 feet deep, and large ridges might exist which are now 
hidden by the clays. 

2. Broad solid ridges or gravel massives one-eighth of a mile or more 
in breadth, separated by the usual intervals. They sometimes have a some- 
what uneven surface, at other times are rather smooth and with slightly 
convex surface. In external appearance they somewhat resemble the small 
deltas, but the horizontal assortment of sediments is much less perfect. 
They usually rise above the clay, and they do not pass into it by degrees. 
Even at their southern border the material is often quite coarse, and never 
finer than medium sand. The clays overlie these gravels at their bases and 
are plainly a later deposit; at least these are their relations on the surface. 
It is possible that in some cases a lower stratum of these plains passes into 
the clays by horizontal transition; but if so, the stratum showing that transi- 
tion is buried out of sight. Often the exposures show conclusively that 
there is no such transition, and nowhere is there proof of it. 

This sort of solid or massive hills closely resembles the plain before 


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GLACIAL GRAVELS OF COASTAL REGION. 379 


described near Freeport (pp. 369-370). It will be convenient to refer to 
them as gravel massives. They are not so common a feature of the discon- 
tinuous osars as of the long osar and broad osar systems. 

3. Reticulated eskers consisting of two or more reticulated ridges 
‘nelosing kettleholes, but not ending in delta-plains, such as the gravels 
near Kast Monmouth. These are a not uncommon form of the gravels. 
The material is nowhere very fine, showing that the waters were not much 
checked. The problem of the reticulations will be referred to hereafter. 

4. Cones, domes, and lenticular short ridges, all with broadly arched 
cross section. As a class these deposits have rather gentle lateral slopes 
and their shapes resemble the drumlins or lenticular hills of till. The 
variety of individual forms is very great. All gradations can be found 
between domes and lenticular mounds on the one extreme and long ridges 
on the other. While they vary in size, height, and slope, yet the prevail- 
ing lateral slopes of the gravels that were below the sea are more gentile 
than those above that level. 


GLACIAL GRAVELS OF THE COASTAL REGION. 
RELATIONS OF GLACIAL GRAVELS TO THE FOSSILIFEROUS MARINE BEDS. 


The glacial gravels are found in three relations to the marine clays. 
First. The gravels have the same level as the clays and pass by degrees 
directly into them. This is the characteristic relation of the glacial deltas 
and marks the coarser glacial sediments as being laid down simultaneously 
with the clays. Second. The clays overlie the glacial gravels, either wholly 
covering them or covering their base. The 
eravels were first deposited within ice walls, 
and subsequently, after the ice had melted, 
the clays were deposited. This arrange- 
ment is so common that for a long time | 
supposed it and the third named to be the 


Fia. 27.—Sheet of marine clay overlying osar, 


only ones, the first being accounted for as 
due, not to original deposition, but to the subsequent action of the sea 
in remodeling the sediments. This was based on an exaggerated idea of 
the power of the sea to erode and transport. Third. The sand and gravel 
of the upper parts of the osar gravels overlie the fossiliferous clays which 
cover the bases of the same kames or osars. This happens in many cases, 


380 GLACIAL GRAVELS OF MAINE. 


but, so far as I have noted, only in places where the ridges would be 
exposed to the surf. The fact could be accounted for in two ways: 

1. The ridges were first deposited within ice walls. Subsequently the 
ice melted and sea water covered the ridges. Marine clay, or in some cases 
kame or osar border clay, was now laid down, covering the bases of all the 
ridges and the whole of the smaller ridges or osars, and a thin sheet of 
clay may have been spread over the tops of even the highest ridges that 
were under the sea. During the retreat of the sea to its present level the 
surf must have suc- 
cessively beat upon 
every part of the 
land as it emerged 
from the water. In 


exposed situations 


Fic. 28.—Marine clay overlying base of osar, and itself covered with a capping of 


gravel; Corinth. the waves would be 
able to erode the upper portions of such gravel masses as rose above the clays 
and to leave the matter in quaquaversal or anticlinal stratification along the 
lower slopes of the ridges and extending out a few feet or yards over the clay 
previously deposited upon the base of the gravel. In Carmel, Clinton, 
Detroit, and many other towns, wells dug in the flanks of the osars almost 


invariably are dug through a thin stratum of gravel, then through clay 
containing shells, and finally into a deep stratum of gravel in which water 
isfound. The upper gravel 
extends only a short dis- 
tance from the central ridge. 

2. According to an- 


Fic. 29 


Marine clay and sand in the midst of osar gravel; Hermon Pond. 


other theory, the sand and 
gravel which overlie the clay on the flanks of the osars may have been 
brought there by glacial streams. On this theory some of the coarser 
matter was swept out to sea for short distances beyond the retreating ice 
front and deposited over the marine clays that had already been laid down 
in the open sea. The theory would make the sand and gravel overlying 
the marine clay a sort of marine delta. The subject will be discussed more 
fully later. If the glacial gravel at Portland overlies the fossiliferous 
marine clays, it may do so in the manner here indicated, or if at the base 
it overlies the clays, this would form a fourth arrangement of the gravels 


GLACIAL GRAVELS OF COASTAL R&GION. 381 


and clays. The difficulty of accounting for the deposition of gravel in the 
open sea without the formation of a delta is very great, if not insuperable. 

A very important fact to be noted relates to the size of the gravel 
deposits at different elevations and distances from the coast. The osars and. 
broad osars become discontinuous at or below the contour of 230 feet, but 
the longer gravel systems are continuous farther south than the shorter 
ones. But no matter how large the gravel systems are, they all become 
discontinuous before reaching the present shore of the sea. Invariably the 
size of the osars and osar terraces becomes smaller as we go south from the 
contour of 230 feet, and the intervals between the successive deposits 
increase. ‘This remark applies to the solid ridges and domes. The marine 
deltas which here and there appear in the midst of the line of lenticular 
ridges interrupt the symmetry of the development, since they are much 
larger than the ridges and domes situated in the series both north and 
south of them. But measured among themselves, as a class, the marine 
deltas are largest near the con- 
tour of 230 feet and diminish in 
size southward. This rule can 
not always be proved—as, for 
instance, in ease of the Katahdin Bea ETON CNG INPUTS SOs GEER Seva 


system, where the deltas are situated in different drainage basins and it 
is difficult to compute the average depth of the delta. Apparently the 
delta west and northwest of Deblois is the largest of the system. It is that 
which is situated farthest south. But the case is complicated by the fact 
that the Seboois-Kingman system may have helped form this delta, and 
also by the fact that it rises nearer the 230-foot level than the Silsby Plains 
situated 20 miles northwest. The great development of the glacial sedi- 
ments not far from the contour of 230 feet is still further aided by several 
of the larger gravel systems of the Androscoggin Valley which come down 
to near or a little below that elevation and then end—the Chesterville- 
Leeds, Canton-Auburn, Peru-Buckfield, and Sumner-Minot systems. 

In most cases the gravel systems of all types end before they reach 
the line of the present coast. ‘The ridges grow shorter and smaller till they 
are only heaps 10 to 15 feet high, while the intervals between them grow 
on the average larger. In Western phrase, the gravels ‘peter out.” The 
only places where they plainly end in bluffs on the shore are at the north 


382 GLACIAL GRAVELS OF MAINE. 


ends of bays or fiords considerably north of the general coast line. ‘Thus 
two systems end in Belfast Bay and one in the north end of Penobscot 
Bay. The Clinton system ends very near the fiord known as Sheepscot 
River, and another comes almost to Cobscook Bay, in Pembroke, and 
another near the sea at Waldoboro. Since the deposits become smaller 
toward the south, it is possible that some of the systems really extend 
farther than they seem, the small deposits of gravel which form their 
southern ends being covered by the marine clays. But in many cases this 
can not be admitted. Thus three systems seem to end near the Head of 
the Tide, Belfast. One of them, if extended, would be found beneath Bel- 
fast Bay, but the two more westerly systems would cross the city of Belfast, 
where excavations for wells, foundations, etc., are so numerous that the 
gravels would certainly have been discovered. In these cases and in most. 
of the gravel systems the evidence that they really end before reaching the 
sea is satisfactory. Another exception is found on the coast from Scarboro 
for many miles southward. The shore is formed of marine-delta sand. It 
is difficult to estimate how far the delta originally extended out mto the 
region at present covered by the ocean. In Jonesport a plain of glacial 
sand reaches nearly to tide water. With the exceptions named the gravel 
systems all end north of the present shore, and in most cases only 10 to 50 
feet above sea level. 


LENTICULAR SHAPE OF THE COASTAL GRAVEL MASSES. 


At Winslows Mills a round-topped hummock of glacial gravel les 
directly beneath the more northern ridge of the Waldoboro moraine. It 
was exposed by excavations made during the building of the dam and mills. 
At the time of my visit the gravel had fallen into the excavation so as to 
make it impossible to determine what was the original nature of the stratifi- 
cation. Enough could be seen of the general shape of the mass of gravel 
and cobbles to show that it does not materially differ in external form from 
the other hillocks of the system of glacial gravel of which this forms a part. 
This is a discontinuous system which extends from near the sea at Waldo- 
boro northward along the valley of the Medomac to a point somewhat more 
than a mile north of the moraine at Winslows. The moraine lies directly 
on the gravel dome, without transition beds. I could discover no sign that 
the glacial stream which deposited the gravel was flowing at the time the 


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LENTICULAR SHAPE OF COASTAL GRAVEL MASSES. 383 


moraine was itself deposited. The moraine near the esker showed no more 
sign of water wash than at a distance. The lenticular eskers or short osars 
extend about 3 miles south of the moraine and along a curved valley. We 
can not admit that these small hummocks separated by intervals of one-fourth 
mile or less could be formed in the open sea by a glacial stream issuing 
from the ice front while the moraine was forming. Their materials as well 
as their shapes testify that they were formed within ice walls by currents 
that at no time were checked as they would have been if poured into the open 
sea. The hummock underneath the moraine has the proper shape, size, 
position, and composition of one of the parts of this system. If at this point 


Fic. 31.—Lenticular esker flanked with blowing marine sand; Bowdoin. 


a subglacial river continued to flow during the time the moraine was being 
formed, it ought to have more or less washed away the moraine and left, not 
a line of discontinuous hummocks separated by intervals, but continuous 
ridges or delta-plains of frontal gravel extending south from the moraine. 
The same would be true of a superficial stream. This makes it probable 
that there is no genetic connection between the hummock that underlies the 
moraine and the moraine itself. More probably the gravel system had all 
been deposited prior to the moraine, and at the time of the moraine the 
glacial stream had ceased to flow in this part of its former channel, or was 
too feeble to form such deposits. 


6 


It is possible that the Waldoboro moraine was due to an advance of 


384 GLACIAL GRAVELS OF MAINE. 


the ice after it had once retreated northward of this point. Any great 
readvance would imply general or climatic increase of intensity of glacial 
conditions. If so, we ought to find similar moraines all along the coast. 
The few short moraines certainly demand pauses in the retreat of the ice, 
and they may indicate a readvance. In either case the moraine must have 
been formed while the ice was in motion. The conclusion follows that if 
the ice was not stagnant at the time of the moraine it could not have been 
at any time previous. Its motion at the time of the deposition of the 
moraine was a continuation of the motion it had had previously and con- 
tinuously. The situation of the place was here favorable to the continuance 
of the flow up to the last. 

Three inferences are indicated. 1. The Waldoboro system of discon- 
tinuous gravels was formed while the ice was in motion. 2. The osar 
beneath the moraine proves that the thin ice of that time (less than 200 
feet in thickness) could flow over gravel ridges or domes without pushing 
them forward. 3. This gravel was probably deposited in a subglacial 
channel. 

In the valley of Georges River, and also near Belfast, we find several 
discontinuous systems of gravels. In these localities the direction of the 
ice flow during the last part of the Glacial period was many degrees different 
from the earlier flow, as is conclusively proved by two or more series of 
glacial scratches. The systems of lenticular eskers follow the direction of 
the scratches last made. They date, then, from a late period, when the ice 
could no longer flow over the higher hills, but was forced to flow around 
them. 

The fact that the series of lenticular eskers are so nearly parallel with 
the direction of ice flow favors the hypothesis that they were formed 
beneath the ice by subglacial streams. In several places, as near Union, 
the surface layers of the northern sides of the lenticular gravel hills are 
crumpled and distorted, while beneath these layers the stratification is, in 
the cases observed, perfect. Such surface distortion might result from the 
direct pressure of ice flowing over the gravel hillock, or it may be due to 
the settling of gravel deposited over ice. Thus it is possible that pieces of 
ice containing morainal matter may break away from the roofs of tunnels 
and be rolled along for a time like stones. If such were deposited as a 
part of a mass of glacial gravel, the melting of the ice subsequently would 


LENTICULAR SHAPE OF COASTAL GRAVEL MASSES. 385 


distort the stratification. So also where flowing ice abutted against a sub- 
glacial mass of gravel it might often do so unevenly, so that cavities of 
unequal thickness would lie between the ice and gravel. Into these, if new 
gravels were deposited, the subsequent advance or melting of the ice would 
change or obliterate the stratification. If such distortions were prevailingly 
on the stoss side of the gravel hillocks, as they were in the places examined, 
motion of the ice during the formation of the gravel deposit would be 
indicated, and also subglacial origin. That subglacial streams abounded 
near the coast is directly proved by the glacial potholes, also by the pres- 
ence of the hummocks of glacial gravel directly beneath the Waldoboro 
moraine, and by other facts. 

The general inference follows that the lenticular kames were formed 
beneath the ice at a time when it was so thin that it was forced to flow 
over them without pushing them forward and incorporating them with the 
till of the terminal moraine, as appears to have been the case at the great 
outermost terminal moraines. And if these lenticular masses were formed 
beneath flowing ice, their shapes must be due in part to the same forces 
that produced the lenticular hills of till. Like the latter, the surfaces of 
the gravels were molded into the forms of stability by the ice as it flowed 
over them. But in the case of the drumlin the ice pressure was a com- 
paratively constant quantity, while in the esker the action of the water in 
melting and eroding the ice was a controlling agency to change the pres- 
sure and in part to mold the form. The ice, as it advanced, found the 
head of its columns literally melting away, so that if the supply of water 
continued, the enlargement of the channel might often proceed even more 
rapidly than the advance of the ice. During the summer time if these 
lenticular gravel hills were formed at the base of “glacier mills,” it is 
doubtful if the ice could advance so fast as to impinge against the kame. 
But during the winter, when the supply of water was small and almost 
all of it ice cold, the amount of melting and erosion would be greatly 
reduced. Now and then the ice would abut against the gravel and be 
forced to flow over it, at the same time helping to carve it into the len- 
ticular form. Indirectly the flow of the water in the space between the 
gravel and the ice of the glacier—a space caused by the gradual melting 
and erosion of the advancing ice—would tend to the broadly arched form 


of gravels. Yet since the water would erode and melt the ice somewhat 
MON XxXxIlvy——2 


386 GLACIAL GRAVELS OF MAINE. 


irregularly, we can not expect the gravels to be so symmetrical in shape as 
the drumlins. 

The lenticular eskers or osars, then, have the natural form that a short 
mass of gravel takes when formed beneath flowing ice. This hypothesis 
assumes that the present deposits were stationary and the ice flowed over 
them. It is barely possible that a glacial waterfall where a surface stream 
falls down a crevasse may form a series of enlargements at intervals, and 
that these enlargements may be pushed bodily forward with their con- 
tinued gravels. This would imply thick ice and small masses of gravel. 
At the time the present lenses were formed the ice could not push forward 
the gravels, but, as at Winslows Mills, flowed over them, only now and 
then distorting the stratification on the stoss sides. The question whether 
the continuous ridges began as a series of separated lenses which at last 
became confluent will be referred to later. 


DECREASE OF GLACIAL GRAVELS TOWARD THE COAST. 


As has already been repeatedly stated, the maximum development of 
the coarser glacial sediments occurs near the highest sea level, which im the 
coast region is not far from the contour of 230 feet. 

Among the causes of great precipitation at this elevation may be men- 
tioned the following: 

1. The length of time the sea stood near that elevation. That the 
changes of level of the sea with respect to the land were geologically rapid 
is proved by the fact that the till was only partially eroded over the sub- 
merged area. I have found no cliffs of erosion in the rock, and thus have 
no proof of long pauses in either the advance or the retreat, and therefore 
assume that the rise and fall of the sea were somewhat uniform in rate. If 
so, it follows that it stood near its highest level for a longer time than at 
any other—that is, during the last part of the period of advance, the time of 
stationary level, and the earlier part of the retreat. During this period the 
modern rivers began to flow and form deltas off the shore of that time. 
Thus a vast quantity of sediment was stopped near the highest shore-line. 
It could not reach farther south because checked in its motion soon after 
entering the sea. 

2. The effect of steeper land slopes north of the contour of 230 feet. 
By a coincidence the slopes of the land are steeper to the north of the 


GLACIAL GRAVELS OF COASTAL REGION. 387 


230-foot contour over large parts of the State. The steeper slopes were areas 
of greater than average denudation by glacial rivers, and the more level 
plains were areas of accumulation. The marine deltas of York and Cum- 
berland counties pass upward into great tracts of reticulated ridges that 
rise to 450 or 500 feet in a few of the valleys, but the deltas in that part 
of the State are at 230 to 250 feet. Obviously the proximity of the change 
in slopes with the old shore line is a mere coincidence. 

3. Possibly a more rapid rate of melting. The lower marine clays are 
blue to black in color and are very fine grained and often richly fossiliferous. 
The later marine clays pass upward as the basal clays of the valleys, they 
are lighter in color, they seldom contain fossils, and in general they are a 
little coarser grained. Evidently quiet conditions prevailed for a time after 
the ocean advanced and animal life flourished. Later the conditions were 
unfavorable. If due in part to the great inflow of fresh water, this proves 
more abundant fresh waters. If due to the muddiness of the water, the 
streams must have been rapid, which could be accounted for by increase in 
the size of the streams or by steeper land slopes. Apparently the reeleva- 
tion of the land took place after the upper marine clays were deposited. 
The advance of the sea over considerable portions of the land ought to have 
helped to ameliorate the climate at the time it stood at its highest level 
irrespective of other conditions. On the whole, we conclude that while it is 
not positively proved that there was any marked increase in the flow of 
fresh waters into the sea at the time it stood at its highest level, yet this is 
probable. 

The above-cited causes help to account for a large development of the 
glacial sediments at or near the highest shore-line. In comparing the 
gravels at this elevation with those found near the present shore, we are 

confronted by an important question: Did the ice retreat from the coast 
region before the advance of the sea? 

If this had happened, we ought in that region to find over sacl gravels 
and terminal kames, such as naturally mark the recession of ice on the 
land <A good place to look for such gravels is at the Waldoboro terminal 
moraine. It is 6 miles long and crosses two valleys favorable to the forma- 
tion of overwash aprons. At the road from Waldoboro to North Waldoboro 
are a few bars of subangular gravel that probably are an overwash deposit 
made while the moraine was being formed. If there is any other overwash 


388 GLACIAL GRAVELS OF MAINE. 


matter it is thin and covered by the marine clays. I found none exposed 
in the banks of the Medomac River, though the discontinuous osar gravels 
are easily traced. 

Frontal gravels ought especially to be abundant in the valleys of the 
larger streams, such as the Penobscot and Kennebec, if the ice melted over 
them before the rise of the sea, and we do not find them. On the contrary, 
they do not either of them show even a marine delta near the rivers, though 
there are a few situated a few miles back from the rivers. 

The conclusion follows that the ice had not melted over the coast 
region previous to the rise of the sea over this area. The retreat of the ice 
front was accompanied by the advance of the sea, if not in part caused by it. 

A related question refers to the earliest glacial sediments of the ice- 
sheets. As before noted, the ice front during the time of thickest ice must 
have been far out in the present Gulf of Maine. While a part of the wast- 
age then took the form of berg discharge, yet there must have been sub- 
glacial rivers which deposited more or less glacial sediment near the ice 
front. We do not know what development these gravels took, or how far 
they were incorporated with moraines and berg droppings, nor do we know 
the extreme depth beneath the sea to which a subglacial stream can pene- 
trate and retain sufficient velocity to transport sediment. Omitting details, 
we can at least affirm that the earliest glacial gravels are now under the ocean. 

What is the date of the earliest gravels now exposed on the land? As 
elsewhere stated more fully, in the coast region there are several places 
where the glacial gravel systems follow the scratches last made when the 
ice was deflected by hills and therefore much reduced in thickness from the 
maximum. These reach as far southward as any of the systems except 
the great ones that come to Portland, Jonesport, and Columbia, and appear 
to be as old as any, with perhaps these exceptions. This gives field support 
to what we should expect from general considerations—that the osars were 

not deposited till the later days of the ice-sheet. 

In comparing the quantity of the coast gravels with those of the inte- 
rior, we have to consider the effect of the position of the néyé line at various 
periods of the ice-sheet’s history. I conceive that only under extraordinary 
conditions is the névé line stationary during periods of the advance and 
the retreat of the ice front. It is perhaps possible that there can be such a 
balance of circumstances—such as length of the glacier, surface gradients, 


GLACIAL GRAVELS OF COASTAL REGION. 389 


rates of precipitation, changes in seasonal temperature, and other climatic 
conditions—that a glacier can grow thinner and finally disappear without 
change in the horizontal position of the névé border. But in the case of a 
great ice-sheet, subject to other than local conditions, it seems to be highly 
probable that there was a retrogression of the névé border comparable with 
the retreat of the ice front itself. If so, there must have been a time when 
the area of the zone of wastage from melting attained a maximum over 
Maine. Previous to that time part of the zone of wastage had extended 
southward, where the ocean now is, and took the form of iceberg discharge. 
As the névé border retreated north the area of wastage by melting that was 
over the land broadened till the time when the outer margin had retreated 
back to the present coast. Whether the névé border of the ice front would 
retreat the faster after that is uncertain, since we do not know what effect 
the rising sea had in melting the ice before it. Leaving open the question 
as to when the area of the zone of wastage from melting over Maine was 
greatest, we can at least conclude that so rapid a decrease in the quantity 
of gravels as takes place within 30 miles of the coast could not have been 
caused, unless in small measure, by changes in the position of the névé 
line. This may have had some effect, but it seems improbable that its 
effect could all be concentrated within so narrow a belt and be so con- 
spicuous here while hardly traceable elsewhere. 

The causes above stated account for the great development of the 
gravels near the highest level of the sea, but throw only partial light on 
the causes of the rapid decrease in the gravels toward the coast. The 
subject is so closely related to the fact that as the gravels become scanty 
they also become increasingly discontinuous, that the further treatment of 
the subject is postponed and will be considered in connection with the latter 
topic. 

SUMMARY. 

The most important characteristics of the glacial sediments of the 
coast region are the following: 

1. Most of the systems contain one or more marine deltas situated at 
different distances from the coast. These deltas are interpolated in the midst 
of the linear series of glacial gravels that were deposited within ice walls. 

2. The continuous osars and osar terraces of the interior as they 
approach the coast break up into ridges separated by intervals. Toward 


390 GLACIAL GRAVELS OF MAINE. 


the south the intervals become on the average longer and the ridges shorter, 
till the latter are reduced to cones, domes, and short ridges or plains. The 
deposits continue to become smaller, and the systems end north of the aver- 
age line of the coast, and most of them only a few feet above it. 

3. The maximum development of the glacial sediments is found near 
the contour of 230 feet. 

4. The gravel deposits of the coast region usually have rather gentle 
lateral slopes and convex summits, and as a class they may be referred to 
the lenticular type of eskers. 

5. The other characteristics of the coast gravels, their topographical 
relations, etc., do not differ materially from those of the interior, except that 
in certain places the gravels of the discontinuous systems or the discon- 
tinuous portions of the osars and osar-plains have the marked characteristic 
of appearing on the tops of low hills (less than 120 feet high), while in the 
intervening valleys gravels are seldom found. 

The above-named facts present special difficulties of interpretation. It 
is certain that some of the gravels were deposited in the open sea, others in 
ice channels, but we have to determine, if possible, whether the latter were 
deposited beneath sea level. Observations made on the land can give us little 
help in studying offshore deposits; and we are haunted in our investigation 
by the uncertainties attending the determination of the border line of the 
névé. We are able to point out certain agencies that must have been 
engaged in the work, but a satisfactory explanation demands a quantitative 
estimate of their relative efficiency. This field of investigation is untrod- 
den as the névé of the ice-sheet itself, and my views have not infrequently 
changed while studying the subject. It seems impossible to take up these 
questions at any point without anticipating later discussions. 


RETREATAL PHENOMENA. 


A topic germane to a comparison of the discontinuous coastal gravels 
with those of the interior of the State pertains to the manner of retreat of 
the ice over a country so diversified by hills and valleys as Maine at a time 
when a considerable part of the State lay beneath sea-level. Thus, if the 
terminal melting was either more or less rapid where the ice was in contact 
with the salt water than where it was above the sea, the retreatal phenomena 
would be very complex. The ice of the drainage basins of many of the 


RETREATAL PHENOMENA. 391 


glacial rivers would not only be attacked from the front lengthwise of their 
courses, but often might be cut off by the sea penetrating transverse valleys 
and thus arresting their flow at some point many miles to the north of their 
previous mouths. Thus, from the north end of the Georges River discon- 
tinuous osar system in Searsmont it is a less distance eastward to Belfast 
Bay than southward to the coast at Thomaston or St. George. 

In marking the lines of synchronous retreat of the ice front the deposits 
we have to depend on are, first, terminal moraines; second, marine glacial 


deltas; third, frontal or overwash aprons of glacial sediments. There are 


many such deposits in Maine, but unfortunately they are several or many 
miles apart and no contemporaneous deposits connecting them have as yet 
been recognized. In the table on page 393 these deposits are divided into 
classes. The order of deposition was first determined for each glacial river 
separately. Of two neighboring deltas the one that was north of a line 
passing through the other parallel to the general coast line was assumed to 
be the later deposit. This assumption is unsafe, but is the best practicable 
test at present. Obviously the rate of retreat of the ice front is determined 
by the ratio between the rate of terminal melting and ice flow. Naturally 
the symmetry of the retreat is much marred in a hilly country, and may be 
still more in a country where the deeper valleys for 100 miles or more from 
the coast were beneath sea level. If the ice melted more rapidly before 
the advancing sea than on the land above sea level, then long bays on the 
fiords of the sea would deeply penetrate the border of the ice; if slower, 
there would be formed lobes of the ice reaching as capes into the sea. Thus 
the long. Penobscot and Kennebec valleys were at that time below sea level 
for more than 100 miles. Their general trend is nearly parallel with that 
of the ice flow, and both open northward into numerous tributary valleys. 
They were thus favorably situated for a rapid rate of ice flow. 

Two glacial rivers flowed from the Penobscot Valley eastward through 
low passes into the valley of Union River, where they deposited large 
marine deltas that demand considerable time for their deposition. One of 
these overflows was from Clifton to Otis, the other from Greenfield to 
Aurora. Manifestly in both cases the ice lmgered in the Penobscot Valley 
all the time they were forming, while the open sea prevailed over the valley 
of Union River. Both glacial rivers departed from places in the Penobscot 
Valley that were considerably below the highest sea level. The distance 


392 GLACIAL GRAVELS OF MAINE. 


from Clifton to Penobscot Bay is about the same as from Otis to the mouth 
of the Union River. If the sea that rose on the land was so warm that the 
ice melted before it as fast or almost as fast as the sea rose, then the ice 
would have retreated in the Penobscot Valley to Clifton as soon or nearly 
as soon as it retreated to Otis in the other valley. This would arrest the 
flow eastward of the glacial river. If any delta formed in Otis it would 
have been very small instead of large, as it really is. The same reasoning 
applies to the overflow to Aurora. 

Several inferences follow. Although the sea was deeper in the Penob- 
scot Valley, yet the retreat of the ice was relatively slower in this valley 
than in that of Union River. Part of this difference may be due to the 
southeastward motion of the ice, but in any case we know that the ice 
could flow into regions below sea level and maintain itself for a considerable 
time. The sea was cold, and ice in it melted slowly. Comparing two val- 
leys, both beneath the sea level of that time, the one most favorably situ- 
ated for a rapid flow of the ice showed a slower rate of retreat than the 
other, where the flow of the ice from the north was embarrassed by trans- 
verse hills. 

Elsewhere are described the glacial lakes that were formed near Lead 
Mountain, Beddington. These were formed in level grounds south of hills 
that would early arrest the flow of ice from the north. For many miles the 
glacial river that deposited gravels in these lakes flowed a half mile or more 
west of the Narraguagus River and on ground 50 to 100 or more feet above 
it. During all the time the glacial river was flowing into the lakes the 
deeper river valley was filled with solid ice to a point south of the lakes at 
least. In other words, the ice in lee of hills melted sooner than the ice 
in the adjacent north-and-south valley favorable to a rapid flow from the 
north. This happened above the highest sea level. 

Thus both above and beneath the sea we have proof of a lobate front 
during the retreat of the ice, but thus far no definite means of comparing 
the relative rates of retreat in the two cases. 

The lines of synchronal retreat were drawn on the map (Pl. XXXT) 
to connect deposits independently determined to belong to approximately 
the same stages of retreat, as set forth in detail in the table. When the 
given points are so few it is manifestly impossible to exhibit the narrower 
sinuses and lobes that probably marked the actual lines of retreat. 


U. S. GEOLOGICAL SURVEY MONOGRAPH XXXIV PL. XXXI 


6T" 


MAP OF 


MAINE 


SHOWING APPROXIMATELY THE LINES OF FRONTAL 
RETREAT OF THE ICE 
BY 
GEORGE H. STONE 


os _10 20 30 40 ‘50 STATUTE MILES 
eS 


ae we IE ~ A 


A.Hoen & Co, lith. Baltimore 


at 
Be nt. 
Sayest ys 


SYNCHRONOUS GLACIAL DEPOSITS. 393 


The following list gives the data on which the lines were drawn on the 
map. It must be considered as tentative, not final. 


List of approximately synchronous glacial deposits. 


| 
Localities. | Kind of deposit. 


FIRST SERIES. 


Machias, near Little Kennebec Bay...-....... | Terminal moraine, 
_ Jonesboro and Jonesport ........-....--...-.-| Gravel massives, apparently 
) passing into the sea. | 
Warn Qin epeee see asecrin-cra ss Sour secon Seer | Delta. 
RWVall OD OLO PRS i= erisinis eo scisjee wane ae eee | Terminal moraine. 
INonthip aninoie Nn eee eee eee ere | Delta. 
Stevens Plain, Deering -......---....--. ahr Do. 


SECOND SERIES. 


Meddybemps-Dennysyville.....-..--....-..-..- Delta. 
Old Stream Plains, in part.................... Do. 
Montag le Plaingee-aceeeeecreo aes eeee eee Do. 
Mebloisanduvaieimibyees- eeee eee eee eee Do. 
ObispandeAtmnorar sere yee oes eae ee eee Deltas. 
IMONTO CW-csetess so csue ees seat eet ea | Delta. 
NyalldoyandeBrookseeeeeeneeseeen see aoe eens | Do. 
North Searsmont, Liberty, and Appleton... .. | Deltas. 
Wiashinotons os. stsen seceoce cee eee eres | Delta. 
WINS OLR emo Seem cies at ioe ee ae ae ee Do. 
nitehhiel dub lai mies seen eee ate aoe ete | Do 
West Bowdoin (Pine Nursery) ...--..-...---.- | Do. 
Wath Cina nsmlennGl 25 2555 sceg coosec ores soebes Do. 
Gorham and North Searboro.-.--.........._.. Deltas and gravel massives. | 


Codywillertee oy secoe cae ace nace ee | Marine glacial delta. 

OldtS tream\ Plain se=- esse eee eee eee eee Deltas 

Race Ground near Machias River .-........... Do 

Greenbush, Greenfield, and Milford........_.. Do. | 
Dixmont, Unity, and Thorndike....--........ Deltas. | 
Belgrade, Sidney, and Augusta............... Delta. 

Salbabisvallleeees eae eee ee ree eal Nenminalmoraines 

New Gloucester and Gray. ---- -.-.---.-...-._. | Delta. 

Standish= imine tones sete eee eeeee lene | Do. 


FOURTH SERIES. ‘ | 


| 
Ornewillle=-Wa Granee) 222-2222 eee ae eee eee) Delta? 
Harmony, valley of Half Moon Stream.....-. | Valley drift and marine 
beds. 


JRERGHIG Gl A. Seca Nee eer amee oe cen aa | Terminal moraine. 


O94 


GLACIAL GRAVELS OF MAINE. 


List of approximately synchronous glacial deposits—Continued. 


Localities. Kind of deposit. 
(Cimps Chonan, ILEGMS 26 cosscosoceaed cosa coos Delta. 
iMimner- North AnD URn yess =e eee erase sepa ae Do. 
olen! COMME 6 aos ank Soscos tameascsaos S00 Do. 


FIFTH SERIES. 


Baldwin and Saco Valley.--.-.-.....-..-..---- 
SOWIN AWS sass sooo esce sees oscseS noncseHsoos6 
Sumner and Bucktield 2.2 ss... ---- = 226 se 
Livermore and Jay.-.----.-.---...... Pere oS 
Cornyillleseeaeee eee eee eee a eee oe eee ee 
(CRINGE coacec besides esas bod pocclenecconSmsecce 
2 Wyarqier Aral Comune Sai55 soc edooée senasson docs 


SIXTH SERIES. 


Woodstock, Paris, 
Vernon, Mayfield, Kingsbury, etc. 


Hartford, Jay, Mount 


SEVENTH SERIES, 


State line, Androscoggin River ...-.-.-..----- 


Sunday, Bear, Ellis, Swift, and Wild rivers. at 


Upper Sandy River Valley..---....-....-.---- 


Newsbortlandi.) 5: 21-/22 soccer eee ses eee at } 


Upper Kennebec Valley .-.-------....-.------ 
Blanchard, Piscataquis Valley........---..--- 
Ik ehiey aaa IRON YORU S paesseedonsso500 seeccood 


Seboois#Rivers ses. 2 co2cc ss scinccee eee ae cee 


EIGHTH SERIES. 


UWinnib also Outlet seme eee ne 


Kennebago Valley. 2 - 525 ------ ------ 2s een 
LGU OD) Ony SUREEWM — 5 255 cossnc cae sesseoosuSESsea5 
IPaMlbia JONES 35-55 copsos coocetedcoc secs soos 


eadbettersballls\ieseeemmas ene se esc ci. =e 


Glacial gravels mixed with 
frontal overwash. 

Valley drift passing into 
marine fluviatile delta. 

Glacial marine deltas. 

Valley drift passing into 
fluviatile marine deltas. 

Valley drift and fluviatile 
marine delta. 

Overwash plain and delta? 

Valley drift passing into- 


marine beds. 


Belt of 


eskers. 


short hillside 


Terminal moraine and over- 
| wash gravels. 
| Do. 
Overwash. 
| Do. 
Moraines and overwash. 
Overwash. 
| Do. 
Moraines and overwash. 


Osars and overwash. 


Ridge of till, probably ter- 
| minal moraine. 
Kames and overwash. 
| Osar and overwash. 
Osar. 
Do. 


0 ee a, 


SYSTEMS OF DISCONTINUOUS OSARS. 395 


CAUSES OF NONCONTINUOUS SEDIMENTATION WITHIN ICE CHANNELS. 


The nature of the phenomena here referred to can best be understood 
by consulting the descriptions of the discontinuous and continuous osars, 
also of the osar terraces. They are briefly set forth as follows: If we start 
from a point 30 or 40 miles from the coast and go southward, we find the 
eravels becoming more and more discontinuous (and correspondingly 
smaller in size), and almost all the systems end a short distance from the 
shore and’ at only a few feet above tide water. That gravel systems of 
varying lengths and having very different topographical relations should 
terminate over the whole coast at almost the same level is a remarkable 
fact and apparently associated with the feature of noncontinuity. 

Omitting from present consideration the deltas which were deposited 
in the sea or in lakes sufficiently large, relative to the inflowing glacial 
river, to permit a horizontal classification of sediments from coarse at the 
proximal to the finest clay and rock flour at the distal end, we confine the 
inquiry to sediments deposited in ice-bordered channels or basins, under 
such conditions that the finest of the glacial débris was carried away by 
the glacial rivers and only the coarser left. We premise that each of the 
discontinuous osar systems, as well as the discontinuous portions of the 
osars, was deposited by a single glacial river. The question then resolves 
itself into this: How can a glacial river systematically deposit sediments at 
intervals in its channel and the intervals increase as the size of the gravel 
deposits decreases? 

Noncontinuous sedimentation by a single glacial river might be accom- 
plished in three ways: First, the river might be depositing sediments in two 
or more separate parts of its channel simultaneously, the intermediate por- 
tions of the channel being at the same time areas of erosion and transpor- 
tation; second, sedimentation might proceed by stages, the separated 
deposits being made one after the other, each one being finished before the 
next of the series was begun; third, both these methods might be in 
operation simultaneously in different parts of the same glacial river. 

Again, part of the physical agencies that lead to noncontinuous sedi- 
mentation may be operative only when the tunnels of the subglacial 
streams open beneath the sea or other body of water, and others may 
depend wholly on conditions originating within the glacier itself or on other 


396 GLACIAL GRAVELS OF MAINE. 


conditions independent of the presence of a body of water rising above 
the bottom of the ice at its distal extremity. 

Moving waters drop a portion of their load of sediments when their 
velocity is for any reason diminished, or they havea greater component of 
the force of gravity to overcome, provided they were just able to carry the 
load. 

One cause of a reduced velocity of current is the enlargement of the 
channel. Local enlargements of the tunnel of a subglacial stream, result- 
ing in a localized slowing of the waters, are formed at the bases of cre- 
vasses down which warmed superficial waters pour. They may also form 
in rapids where the waters rebound upward in passing over rocks, or where 
they fall to the ground again and spread laterally, or where the subglacial 
waters rise into crevasses or onto the surface because of insufficient or 
clogged outlets. Perhaps the most important method of enlarging narrow 
tunnels into lake basins is that whereby a large superficial stream forms a 
pool or lake where it pours down its shaft into a subglacial or englacial 
tunnel. Gradually the warmed surface waters melt a large shaft and ulti- 
mately form a pool. If from time to time the outlet became clogged or 
proved insufficient, so that the pool and shaft became filled with water 
exposed at the surface to the sunlight, the melting would be accelerated 
and ultimately a lake would be formed. When once the water of the lake 
became exposed to the sun for a large part of the time, the enlargement 
would be still more rapid. A lake might also form where, on account of 
stoppage of the subglacial stream, the waters rose through crevasses onto 
the ice and absorbed heat from the sun The extension of a subglacial 
stream northward incidental to the thinning of the ice might cause a series 
of new crevasses to open across the course of a superficial stream and a 
corresponding series of enlargements at their bases. In these and other 
ways we can account for local enlargements of subglacial tunnels into hol- 
low cones, domes, and caves of various shapes, also into basins open above 
to the air, the impetuous waters acting on the ice both by mechanical 
erosion and by melting. 

When a subglacial stream tunnel passes up and over a hill or opens at 
the ice front beneath a body of water, some special phenomena demand 
notice. The water in the tunnel below the top of the hill or surface of the 
body of water (making allowance for the difference in the specific gravity 


NONCONTINUOUS SEDIMENTATION IN ICE CHANNELS, 397 


of the glacial and the frontal water) is in equilibrium. This part of the 
tunnel and all its connecting crevasses are permanantly filled with water 
that can flow only when there is an effective head of water rising above or 
behind it. At the proximal end of this permanent body of water the 
streams in summer flow with such velocity as to keep their channels clear 
of sediment, but during the fall and winter the small streams are checked 
as they flow into the body of permanent water and deposit their sediments, 
probably to wash it away during the next flood. A rising or falling sea or 
frontal lake might under some conditions cause the deposition of a series of 
such sediments formed at the successive levels of the subglacial portions 
of the sea or lake. 

Among the conditions of retreat in presence of a cold sea (the depres- 
sion of the Chiegnecto Peninsula would assist in maintaining a rather cold 
sea on the coast of Maine) is the marginal zone of submarine ice. When a 
glacier ends in a warm body of water, the ice margin overhangs; but when 
it ends in a cold body of water, and especially in salt water that can be 
cooled below 32°, the waves erode the upper ice just as they do other 
rocks, and leave cliffs overhanging the surf, while there is left a shelf of ice 
passing out beneath the sea and from time to time breaking off in blocks 
and rising to the surface." The breadth of this zone of submarine ice 
would be increased if the basal ice contained a considerable quantity of 
glacial débris and thus weighted it down, so as to prevent it from rising as 
bergs. The breadth of this ice would increase during the winter, partly 
because of the colder sea and partly on account of the violence of the 
winter storms in eroding away the upper part of the ice. In summer the 
ice would begin to melt this projecting shelf, and under favorable cireum- 
stances might before autumn melt it all away and even cause an overhang 
of the upper ice. 

If crevasses opened from the subglacial tunnels upward to the surface 
of this submarine ice, the subglacial streams would rise in the crevasses and 
escape on the surface of the sea, partly because their specific gravity is less 
than sea water and partly because they would thus meet less friction. If 
so, the stream would drop much of its sediment at the base of the crevasse. 

Another cause of the diminished velocity of the subglacial streams is a 


1 Russell, Nat. Geog. Mag., vol. 3, p. 101, 1892. 


398 GLACIAL GRAVELS OF MAINE. 


differenual subsidence of the land whereby the proximal extremity of the 
ice-sheet is more depressed than the distal. This effect would be intensified 
if it was accompanied by a corresponding rise of the sea to diminish the 
surface gradient of the waters of the glacial streams. 

In addition to the varying velocities of current that favor sedimenta- 
tion, we also must reckon with friction and the force of gravity. Thus 
manifestly the slopes of the bed of a subglacial stream favor sedimentation 
when the stream leaves a steeper down slope for one less steep or for an up 
slope, since a greater component of the force of gravity is to be overcome. 

Thus far in our discussion we have assumed the ice to be stationary. 
But one of the important works of glacial ice is to push forward the sedi- 
ments that gather in subglacial tunnels. Thus, in the Kettle moraine of 
Wisconsin there are many stones that have been very much rounded by 
water.action and subsequently thrust forward and incorporated*with the — 
other morainal matter. The same phenomenon is seen at the larger termi- 
nal moraines of the Rocky Mountains. When the rate of ice flow is rapid 
and the larger part of the débris is superficial, all or nearly all the glacial 
gravel is brought forward to the front of the ice, partly by the streams and 
partly by ice pushing. A considerable part of the waterworn matter is left 
as a part of the moraine in most cases. Indeed, it is difficult to account for 
gravels being deposited in transverse tunnels, or in the transverse portions 
of tunnels, without being pushed forward, while the ice remains deep and 
the flow rapid. It is equally difficult to account for gravels being pushed 
forward by the ice that were deposited in longitudinal tunnels of uniform 
size. Occasional mounds occupying caves in the base of the ice might be 
pushed forward. Such pushing would probably obliterate the stratification, 
but the floods of the sueceeding summer would restratify it, and at the last, 
when the ice became sufficiently thin, it would no longer be able to thrust 
it onward, but would be forced to flow over it, or at the most could only dis- 
organize a portion of the mass on the stoss side. In like manner we can 
account in part for the failure of the ice to push forward transverse gravels 
at a time of stagnant thin ice and rather rapid rate of enlargement of the 
subglacial channels. . 

When we come to apply these general principles to the problem of the 
coastal gravels of Maine, we note, first, that domes and cones of gravel up 
to one-eighth or eyen one-fourth of a mile wide were left on the tops of low 


NONCONTINUOUS SEDIMENTATION IN ICE CHANNELS. 399 


hills, some of them wholly or largely composed of till. Here great enlarge- 
ments of the glacial channels were formed in places favorable to the pro- 
duction of crevasses. Both to the north and south of these local deposits 
the glacial rivers left no gravels, often for a considerable distance. On the 
whole, we must admit that the local situations of such of the coastal 
gravels as cap hills are favorable to local enlargements of the channels of 
the glacial streams, and therefore to sedimentation. The slopes of the hills 
up which much of this sediment must have been transported would also aid 
sedimentation. In other cases there are no relief forms of the land that we 
can connect with the positions of the discontinuous gravel masses. Only 
in part, then, have we field evidence that gravels were deposited at places 
favorable to local enlargements of the stream channels. 

What effect had the marginal zone of submarine ice on the distribution 
of the gravels? 

As elsewhere noted, one of the mounds of the discontinuous Medomaec 
Valley system of gravels lies beneath the moraine at Winslows Mills. The 
material of this mound is much waterworn. If any of the deposits of 
much worn gravel can be connected with the marginal submarine ice, it 
ought to be this, for it bears a definite relation to the ice front at a certain 
period. The opinion is justified elsewhere that the gravels were deposited 
and the glacial stream that left them had ceased to flow before the ice had 
retreated to the position of the moraine. The bars of subangular gravel 
that lie in front of the moraine at the road from Waldoboro to Nerth 
Waldoboro may be frontal gravels, or possibly they were deposited in the 
marginal zone of submarine ice a few rods in front of the moraine. These 
gravels are only a very little worn and are unique in character. If there 
were any gravels deposited in the submarine ice, they would probably be 
more like these than like the more rounded gravels. The rather steep two- 
sided ridges that form the terminal moraines in the coast region point rather 
to overhanging ice than to a projecting wedge of submarine ice as border- 
ing the margin at the times the moraines were deposited. At other times 
it may have been different. 

If a subglacial river dropped its coarser sediment as it went up through 
crevasses in the submarine ice, it ought to have deposited its finer sand and 
clay near by as a delta or overwash apron. Such deposits would be formed 
near the ice margin, for we can not admit any great breadth of submarine . 


400 GLACIAL GRAVELS OF MAINE. 


ice. They would be retreatal, capping older sediments, and but rarely 
would they form an isolated mass by themselves, as I conceive. 

While admitting that some marginal submarine ice probably exists, 
and that it might act in the manner indicated, I have found no certain 
field evidence of this form of ice action. 

Were the discontinuous coastal gravels begun as a series of subglacial 
tide-level deposits during a gradual rising of the sea? 

The answer to this question is short and positive. The discontinuous 
systems cross valleys and hills and gently rolling ground. North of the 
hills the water in the stream channels, no matter whether they were super- 
glacial or subglacial streams, would be dammed by the hills in front. The 
rising of the sea could produce no effect beneath the surface of this glacial 
dam. On a continuous southern slope we might admit as a possibility a 
series of tide-level deposits as inaugurating sedimentation at intervals, but 
by no means on the north sides of hills in confined channels in the ice. 
But in another way we may have proof of the action of the subglacial sea, 
if we may so term the body of glacial water that filled the cavities of the 
ice-sheet up to sea level. The East Machias osar shows a series of broad 
reticulated ridges at the highest sea level, but no delta proper. In Lagrange 
and Orneville, in the Penobscot Valley, and in Canaan and Cornville, in the 
Kennebec Valley, we find near the highest sea level that the long osars 
that follow these valleys for 50 miles expand into plains with some of the 
characters of narrow marine deltas and also of the broad osar terraces. 
Here it is probable that these plains or partial deltas were formed at sea 
level, but at some distance back from the ice front, so that no delta proper 
could be formed. If so, this would prove that enlargements of glacial 
channels and sedimentation took place at the point where the stream flowed 
into the permanent subglacial and submarine body of water. Such deposits 
are, however, very different in structure from the discontinuous gravels of 
the coast region. 

In three instances in Maine osars are conspicuously discontinuous on 
level ground at long distances from the coast. The first instance is that 
of the Katahdin osar near South Lincoln; the second, that of the Moose- 
head Lake osar in Abbott, Guilford, Sangerville, and Dover; the third, the 
Anson-Madison osar in the northwestern part of Anson. In all these cases 
the discontinuous deposits are below the highest sea level, or in a glacial 
lake. A similar coincidence occurs in central New York, where Mr. G. K. 


eS ee ee ee ee ee ee 


NONCONTINUOUS SEDIMENTATION IN ICE CHANNELS. 401 


Gilbert and others have described a frontal glacial lake. At one time it 


lay between the ice on the north and the hills on the south and overflowed 
the Rome divide into the Mohawk Valley. A delta deposited by glacial 
streams in this lake is found in Schroeppel, Oswego County, and extending 
southward into Clay, Onondaga County, and other towns. Over most of 
the Ontario slope in that region there are numerous short ridges and 
mounds of glacial gravel, and some of them are arranged in north-and-south 
lines, suggestive of deposition by a single glacial river. Is this association 


of discontinuous deposits in the course of a single glacial stream, not only 


on the coast of Maine but elsewhere, with the presence of a body of water 
in front of the ice, causal or only acgidental? 

Regarding the cases of discontinuous gravels in Maine at long distances 
from the coast, the problem is complicated by the fact that in two or three 
cases there were other causes that may have been more significant than the 
presence of the frontal body of water. Thus, in Anson we are only 2 or 
3 miles from a large terminal moraine, and the gravels may have formed 
near the ice front as local kames rather than as parts of the original osar, 
dating from a time when the ice of the Carrabassett Valley practically 
formed a local glacier. The conditions in Abbott and Guilford may be 
very similar. 

The first question that arises in this discussion pertains to the effect of 
the presence of the frontal body of water on the development of the sub- 
glacial tunnels. We have seen that when the glacier hes partly below the 
level of the frontal water, the tunnels and the connecting crevasses are per- 
manently filled with glacial waters up to the level of the sea or frontal lake. 
The water in the crevasses would soon attain a temperature of 32° and then 
float above the somewhat warmer water contained in the tunnels below 
them. All the water of surface melting in this part of the glacier would 
fall into the crevasses and become mixed with the water already occupying 
the lower parts of the crevasses. The convection currents would be feeble, 
and but little of the heat brought down by the surface waters would get 
down into the subglacial tunnels and be available for enlarging them. 
Only where the larger surface streams poured into crevasses would the 
surface waters carry a surplus of heat into the subglacial tunnels. ‘The 


-smaller brooks and seeps would be so mixed with the cold waters of the ere- 


vasses that their heat would be expended in melting the ice walls of the 
MON XXXITV——26 


402 GLACIAL GRAVELS OF MAINE. 


crevasses perhaps some hundred feet above the tunnels. Thus over all 
those parts of the ice-sheet where the basal ice was submerged in the sea 
but little of the water of local melting was available for enlarging the 
main tunnels, but the melting was diffused, so to speak, over many times 
as great an ice surface as where the water could pour down a crevasse and 
escape at once along the tunnel, as happens in case of glaciers not flooded 
by basal waters. The net result would be that in the parts of the ice-sheet 
where the basal ice was submerged the subglacial tunnels were far less 
enlarged than they would have been if the gently warmed surface waters 
could have sunk at once into them. It is uncertain how far the outward 
pressure of deep bodies of water can overcome the inward flow of the 
walls of the tunnels, but on the coast of Maine the depth of the perma- 
nent water in the crevasses was at the most only about 200 feet, and it is 
improbable that such a pressure would perform any important work. But 
irrespective of any possible partial collapse of tunnels formed on the land 
as they were pushed beneath the cold sea, we can at least infer that the 
tunnels were not enlarged commensurate with the supply of waters. For 
there was as much water of surface melting here as elsewhere on the gla- 
cier, but it could not help to enlarge the tunnels so much as that above 
sea level. The tunnels naturally were inadequate to carry off the water of 
summer melting as fast as it fell down from above into the crevasses. 
Each crevasse became filled with water above sea level and formed a stand- 


” of water was the 


pipe to the main tunnels. A great hydraulic ‘“heac 
result, but could never be greater than that which was due to the gradient 
of the ice surface, since if the crevasses filled to the top the water would 
then overflow on the ice. The result was a high velocity of the streams in 
their narrow channels with consequent little sedimentation, and that only of 
the coarsest matter and under the most favorable circumstances. The local 
effect of basal waters would be felt by stream channels lying wholly in the 
submerged area as well as by those originating above the sea and pushed 
beneath it. : 

In other words, the normal transfer of heat by surface waters to the 
base of the ice, where it is the chief cause of the enlargement of the sub- 
glacial tunnels, is in a large part arrested where the base of the glacier is 
submerged to any considerable depth, and the heat is expended in melting 
ice in the crevasses far above the tunnels. 


HISTORY OF THE COASTAL GRAVELS. 403 


In a minor and more indirect way the noncontinuous gravels appear 
to owe their peculiar development to the presence of the sea in front of 
the ice. Under any admissible surface gradient of the ice the presence of 
200 or more feet of frontal water rising above the base of the ice would 
arrest the flow of such of the subglacial streams as did not have their 
sources more than 3 to 5 miles back from the front, so as to have sufficient 
head to drive them after the rise of the sea. Several of the shorter dis- 
continuous systems do not exceed this length. In such cases the rising 
of the sea would cause the development of the gravels to cease, and we 
would now find them in that stage in which they happened to be when 
their streams were arrested. If we grant that the sea had no direct, only 
a modifying, effect in causing noncontinuous sedimentation, still it would 
be a not unimportant role to fossilize, so to speak, the work of the shorter 
glacial rivers at a particular period of their history and preserve it for our 
inspection. 

Having thus set forth what appear to be the more important agencies 
in producing noncontinuous sedimentation, it remains to examine them in 
their mutual relations and thus obtaim a more general view of the subject. 


RESUME: HISTORY OF THE COASTAL GRAVELS. 


As already repeatedly noted, the three distinguishing features of the 
discontinuous coastal gravels are their rapid decrease in size toward the 
coast, their occurrence at longer and longer intervals, and their termination 
a short distance north of the shore and at only a few feet above tide water. 
The three phencmena are so widely associated that they would appear to 
have had, in respect to their principal causes, a common origin. 

The history and causation of the coastal glacial sediments, so far as 
now appears, were probably about as follows, assuming that in the coastal 
region of Maine most of the glacial sediments were deposited by subglacial 
streams: ‘ 

If these changes were observed in case of only a few of the gravel 
systems that reach nearest the coast, one here and there, the facts would 
seem to indicate local causes. But when gravel systems are found every 
few miles along 200 miles of coast, all of them exhibiting the first two of 
the above-named characteristics, and all but five the third, we are forced to 


404. | GLACIAL GRAVELS OF MAINE. 


look for agencies operating along the whole coast. Horizontally these 
changes take place within a zone generally not exceeding about 30 miles in 
breadth, but sometimes, especially in the larger north-and-south valleys, 
exceeding that limit. Some of the systems end some distance back from the 
coast in marine deltas, and such are not here included among the coastal 
gravels proper. The southern ends of such of the systems as reach nearest 
the coast lie approximately at or near the northern ends of the bays or 
fiords of the coast. Vertically the northern ends of the discontinuous sys- 
tems are found at elevations from 50 up to 350 feet; their southern ends 
have elevations rather less than 50 feet. 

The existence of numbers of glacial potholes near the shore proves the 
presence of subglacial streams in the coastal region south of the ends of 
the gravel systems. The scantiness or absence of gravels at the shore by no 
means leads to an inquiry as to the local absence or feebleness of subglacial 
streams near the sea. The problem is an entirely different one: How did 
it happen that at nearly the same elevation all but five of the glacial rivers 
along 200 miles of coast found themselves with so large a supply of water, 
as compared with the sizes of their tunnels, that they were able south of 
that line to sweep their tunnels clear of sediments, or nearly so, while above 
that level and to the northward they left, in channels within the ice, sedi- 
ments that rapidly increase in quantity and continuity for 30 miles or more? 
These changes are so great and so rapid that it is practically a revolution 
we have to account for. 

Looking at the rapid transitions as we go north and south, we are 
reminded that the zone of transition is approximately parallel with the 
position of the ice front during the retreat, and we naturally seek for the 
causes of these phenomena in some phase of the ice-sheet’s structure or 
behavior consequent on its final melting and disappearance. On the other 
hand, when we look at the great differences between the osar rivers as to 
size and length; when we see how parallel some of them were to the ice 
flow while others were for long distances transverse; how some flowed in a 
single drainage valley of the land while others spanned several such valleys; 
how some were in broad north-and-south valleys, where the ice flow was 
faster, while others were south of transverse hills, where the flow was slower; 
and yet all but five end before reaching the shore, and there is no proof 
that these five extend far beneath the sea; when we think of the small ver- 


HISTORY OF THE COASTAL GRAVELS. 405 


tical differences between the southern terminations of the gravels left by so 
many glacial rivers, having so many topographical relations and scattered 
over so wide an area, we are driven to seek for agencies capable of acting 
horizontally over the whole coast simultaneously. In view of the great 
differences between the glacial rivers, also of the lobal ice front during the 
retreat, it seems improbable that there was any agency capable of thus 
widely acting so nearly parallel to the surface of the sea except the sea 
itself. 

What conditions of the ice-sheet independent of the sea would tend to 
produce such a development as is shown by the coastal glacial gravels? 

Little or no permanent accumulation of sediments can be made within 
small subglacial or englacial tunnels—small, that is, compared to the flow 
of waters—because of the great velocity of the streams during the summer 
floods. And such they remain while the ice is deep and the rate of flow 
rapid, Before the streams have time greatly to enlarge their channels new 
ice advances from the area of accumulation and the ice containing the tun- 
nels already somewhat enlarged has reached the front, where it is melted or 
discharged as bergs. Under these conditions the rapid subglacial streams 
transport almost all their sediments to near the front of the ice and deposit 
them as marginal kames or beyond the ice as overwash aprons. In this 
they are often assisted by the pushing of the ice. On rather steep down 
slopes, especially where the waters are collected in the lower parts of val- 
leys, these conditions prevail throughout the whole time of the retreat, 
until the glacier becomes too small to support large streams. Thus all the 
larger glaciated valleys of the Rocky Mountains contain retreatal plains 
of frontal gravels up to about 5 miles from their sources. The gravels of 
the Androscoggin River from Bethel to Gorham, New Hampshire, and 
also those of the upper Carrabassett Valley are probably in part of this 
character. 

But when an ice-sheet covers a variety of ‘surface, such as plains and 
gentle down slopes, and especially adverse slopes, or when there is a sub- 
sidence greater toward the source than at the distal extremity, the glacial 
streams become able greatly to enlarge their channels as the ice grows 
thinner and by degrees stagnant, and are no longer able to keep them free 
from sediment. The process of sedimentation begins at favorable places in 
the channels, such as local enlargements, or where obstructions rise on the 


406 GLACIAL GRAVELS OF MAINE. 


beds of the streams, such as rocks or low hills. At first these places are 
few and at long intervals, but as the channels still more enlarge, sedimen- 
tation occurs at shorter intervals, until at last it is practically continuous. 
A deposit once formed that the ice can not push forward becomes a nucleus 
around which more gravel gathers. The resulting narrowing of the 
channel aids in its further enlargement, and thus in process of time very 
great masses are collected. The causes of enlargements of the channels 
have already been noted. 

One class of the coastal gravel deposits demands special attention. 
These are numerous massive mounds, also plains up to 5 or 10 miles in 
length and half as broad. They often contain kettleholes, but their glacial 
character is that of massiveness, and they are by no means so conspicu- 
ously ridged as the plexus of reticulated kames. Often the kettlehole is 
simply a depression in what would otherwise be a mesa or plain with a 
rather level or gently undulating surface.’ 

These deposits are sometimes bordered in part by hills, against which 
they lie like terraces, but they usually end in bluffs, rising above the 
adjacent land. They were evidently formed within ice walls either wholly 
or in part. One of the most remarkable of these bluffs is that along the 
top of which the base line of the Coast and Geodetic Survey was measured ° 
in Deblois and Columbia. Now, if even the largest of the glacial rivers 
flowed into lakes as large as the largest of these plains, they would have 
deposited deltas showing a horizontal assortment of sediments from coarse at 
the proximal to fine clay and rock flour at the distal end. Instead, these 
plains are composed of rather coarse matter—sand, gravel, cobbles, ete.— 
with but little horizontal classification. Some of them are 150 feet in 
height and must contain 10 to 15 square miles of surface. 

The absence of such reticulated ridges as are found at the proximal 
ends of the moraine deltas proves that the subglacial rivers did not flow 
into very large open bodies of water. It is a better interpretation that a 
small channel. or lakelet open to the air was first formed. - These gradually 
enlarged by the lateral melting of their walls, partly by the heat of the 
inflowing waters, but most rapidly from heat directly absorbed from the 
sun. The subglacial and perhaps to some extent the superficial streams 


1See the descriptions of the Portland, Readfield-Brunswick, and Standish-Buxton systems, 
also of the gravels of Gorham, Charlotte, Freeport, Auburn, Jonesboro, Columbia, and Deblois. 


HISTORY OF THE COASTAL GRAVELS. 407 


brought in sediments and dropped them in the lake. If sedimentation 
proceeded at about the same rate as the enlargement of the lake, there 
would never be a space between the central bar of gravel and the ice walls 
wide enough to permit the formation of a-delta, but the finer débris would 
be carried away. The outlets of the lakes were too narrow to permit the 
deposition of sediment within the tunnel until another enlargement or the 
sea was reached. It does not seem probable that the surface waters could 
take down beneath the ice heat enough to produce the larger glacial lakes. 
In such eases we must postulate lakes open to the air and absorbing heat 
from the sun. 

It is not meant to imply that in all cases the gravels were deposited in 
the central parts of the lakes. The essential part of the process is that the 
size and velocity of the streams bear such a ratio to the size of the lake 
that the streams are not sufficiently checked to permit their depositing the 
finer débris. Elsewhere are described the gravels of northeastern Mon- 
mouth, where the glacial river flowed swiftly across the middle of small 
glacial lakes, depositing a terrace of coarse gravel on each side of its course 
and leaving a central ravine to mark its channel. 

Among the possible causes of a small enlargement of the subglacial 
tunnels south of the north ends of the bays or fiords of the coast (fiord 
line) may be mentioned an increased rate of ice flow at that line. The 
fiords continue for some miles beneath the ocean, as is shown by the Coast 
and Geodetic Survey charts, but they are shallow, and on the whole the 
sea floor is less uneven than the land, and the slope southward is somewhat 
steeper than the average land slopes north of the fiord line. We seem, 
then, to have a right to assume that, near the shore, after the ice had passed 
the higher obstructing hills, it would have its rate of motion somewhat accel- 
erated. Crevasses due to tension owing to the more rapid flow toward the 
ice front would be here more abundant than northward, while those due to 
inequalities of the land would be rather less abundant. On the whole, the 
conditions probably favored the restriction of the subglacial channels, but 
it would be difficult to place a quantitative estimate on this agency. 

We must also consider the possibility that the retreat of the ice may 
have been at very unequal rates, and that the gravels formed near or not 
far back from the ice front would be determined in part at least by these 
varying conditions of retreat. If so, we might find corresponding types of 


408 GLACIAL GRAVELS OF MAINE. 


development of the glacial gravels in belts marking certain stages of the 
retreat such as I have not attempted to mark on the map. Thus far I have 
found only two such stages—one at the coast above described, and the: 
other the overwash aprons deposited in valleys above sea level. While it 
is probable that the osars were deposited somewhat recessively, yet the 
absence of well-marked stages traceable in the different systems, except 
such as bear a relation to the old sea level, indicates that the retreat of the 
ice alone was insufficient to account for the termination of so many gravel 
systems at nearly the same elevation. Besides, where the zones of accu- 
mulation and waste were so wide as they must have been in so great an 
ice-sheet, it seems hardly probable that retreatal phenomena would take the 
form of a great transition within so narrow a belt The icé must have 
extended 30 miles beyond Mount Desert Island at the time it flowed over 
that island if it had a surface gradient of 50 feet per mile, which is twice 
the average gradient of the ice surface between there and Mount Katahdin.’ 
Without allowing for berg discharge, the ice would reach 60 miles south of 
the coast, and perhaps actually reached half or two-thirds that distance. 
The coastal gravels may have been deposited 20 or more miles from the 
ice front. Under these conditions it will require direct and positive evi- 
dence to connect the peculiar development of the coastal gravels with any 
marginal phase of retreatal action. Various modifications of the hypothesis. 
suggest themselves, such as a coincidence of the subsidence of the St. 
Lawrence Valley with the close of the period of deposition of the coastal 
gravels, whereby the flow of ice from Canada over the St. John divide was 
impeded and the development of the osars of the interior of the State 
became more perfect than that of the coastal gravels, which was arrested 
while in the earlier stages, ete. 

What conditions favorable to such a development as is exhibited by 
the coastal gravels depended on the sea? 

The subsidence of the land beneath sea level, especially a greater sub- 
sidence toward the north, would destroy part of the effective “head” of the 
subglacial streams. Most of the discontinuous osar systems lie in regions 
that were beneath the sea throughout their whole length. The absence of 
marine deltas favors the conclusion that numbers of the shorter osar rivers. 


1 Distance, 120 miles; elevation of surface at Mount Katahdin, 4,500 feet; at Green Mountain, 
Mount Desert, 1,500 feet. 


ee 


OO  —— —— 


LATE GLACIAL HISTORY OF THE COASTAL REGION. 409 


ceased to flow because of the rise of the sea before the retreat of the ice as 
far back as the southern terminations of the gravel systems—that is, their 
work ceased while they were yet in the early or discontinuous stage of ice- 
channel sedimentation. It is uncertain how far this remark applies to the 
longer rivers that formed no marine deltas. 

As previously pointed out, the subsidence of the ice-covered land 
beneath sea level would cause the tunnels and lower part of the crevasses 
to become permanently filled with water at 32°. The manner in which 
these basal waters tend to restrict the enlargement of the subglacial tunnels 
has been already described at some length. Of all the agencies known to 
me for the production of the coastal gravels and their limitations. this. 
appears to have been the most efficient. 


LATE GLACIAL HISTORY OF THE COASTAL REGION. 


The history of the coastal region appears to have been about as follows: 

Without assuming any definite positions for the southern border of the 
area of accumulation at particular periods of the life of the ice-sheet, we 
may confidently affirm that during the time of maximum glaciation a large 
part of the zone of waste was south of the present shore and that the earlier 
kames and overwash gravels are now beneath the ocean. At the time when 
the coastal gravels were being deposited the higher hills of that region were 
able to deflect the ice from its earlier direction of movement. The height 
of these hills limits the thickness of the ice of this period to not much if 
any more than 1,000 feet, and it may have been considerably less. On the 
other hand, the flow of the osar rivers that deposited the Medomac Valley 
system of discontmuous gravels had ceased at the time the Waldoboro 
moraine was being formed—that is, before the ice had become less than 
100 to 200 feet in depth. The coastal gravels date, then, from the time just 
preceding the retreat of the ice to the present shore, or perhaps to the north 
ends of the fiords. The absence of frontal gravels from the coastal region 
except in the form of marine deltas proves that the sea beat against the 
front of the ice, or at least against its base, during all the time of the 
retreat up to the highest beach. Some of the marine deltas were formed 
not more than 100 feet above the present sea level and only 2 to 5 miles 
north from the southern ends of the gravels of the same systems. We 
infer that the sea had reached at least one-half of its final elevation by the 


410 GLACIAL GRAVELS OF MAINE. 


time the ice had retreated back to these deltas—how much more we do 
not know. We thus reach the conclusion that the sea was somewhat above 
its present level at the time the coastal gravels were deposited, but how 
much is not yet determined by the gravels themselves in their development 
as deltas. 

During the thinning of the ice the subglacial streams were extended 
farther north into regions before drained by superficial streams which were 
situated far up on the glacier and extended into the slush zone of snow. 
None of the basal débris could get up so high above the ground as this, 
and only Mount Katahdin has been supposed to have been above the ice 
surface. This class of superglacial streams could not have deposited the 
coastal or, unless rarely, any other glacial gravels. The class of superficial 
streams that form near the ice front may have assisted in the formation of 
the coastal gravels, as at the marine deltas, the glacial lakes, and by collect- 
ing sediment. which they poured into subglacial tunnels. No matter where 
the névé line had been at the time of deepest ice, it certainly was far north of 
the shore at the time the coastal gravels were deposited, for this was well 
on in the period of retreat. As the névé line retreated northward and the 
subglacial drainage was correspondingly extended, the time came when 
‘that portion of the ice-sheet drained by subglacial rivers was at a maxi- 
mum over the State. Obviously the longer a glacial river is, the greater 
will be the enlargement of its channel, other things being equal. The 
amount of water passing southward at the shore would increase so long as 
the length of the subglacial streams north of the shore was increasing, up 
to the time of the retreat of the ice to that line, if the sea did not interfere 
with the development. The time of maximum subglacial drainage surface 
probably was near the time when the coastal gravels were deposited, or 
somewhat later. This would cause a large flow of water, but not a large 
sedimentation, except where there was a corresponding enlargement of the 
subglacial channels. For a time the base of the ice in the coastal regions 
was flooded with cold waters because of the subsidence beneath the sea, 
and the flow of the ice was probably more rapid south of the fiord line. 
These and other physical causes so far prevented enlargement of the sub- 
glacial tunnels in the coast region that sedimentation became more scanty 
and at longer intervals southward and finally ceased near the fiord line. 
South of this line, in all except a few instances, the glacial rivers were so 


LATE GLACIAL HISTORY OF THE COASTAL REGION. 411 


large, as compared with the capacity of the tunnels, that they were able to 
sweep their tunnels clear of sediments, or nearly so. In many places near 
the coast there were formed at this period glacial lakes too large to be 
ascribed to melting by subglacial waters and which were probably open 
above to the sun. The ice could have been only a few hundred feet deep 
at the time of their formation. They appear to have been formed by 


- gradual enlargement around a growing plain of gravel. Numerous marine 


deltas are found in this region, sometimes alternating in the course of the 
same gravel system with the massives or plains deposited in the glacial 
lakes, which massives show little or none of the horizontal assortment of 
sediments belonging to the delta deposited in still water. The deltas and 
terminal moraines mark lines of retreat, but it is difficult to synchronize 
them. 

SUMMARY. 

The waters of surface melting utilize the crevasses of the glacier for 
penetrating to the bottom of the ice or into it, where they force a passage 
along the crevasses or beneath the ice, assisted more or less by the basal 
waters and furrows in the base of the ice. 

The narrow channels due to fracture or the crannies which the waters. 
open by their pressure are enlarged by melting and mechanical erosion into 
tunnels which sometimes expand into chambers, caves, and channels of 
various shapes and sizes, and may open above to the sunlight. 

Other things being equal, when glaciers lie on the land and disappear 
by melting without berg discharge, the amount of enlargement of the 
tunnels varies directly as the time they are being enlarged, i. e., inversely 
as the rate of ice motion. 

The enlargement of the tunnels is antagonized by a slow inward flow 
of the ice walls. The laws that govern the rate of inward flow, how far 
the rate is determined by the depth of ice or by variations of pressure 
caused by the ice movement over obstacles or by heat transmitted through 
the ice, etc., are unknown. 

The transfer of energy beneath the glacier by gently warmed surface 
waters, the heat of which is generally available for the enlargement of the 
subglacial or englacial tunnels by melting their walls, is greatly hindered 
when the glacier flows into a body of water, since, as the warmed waters 
pour into the cold waters that bathe the basal ice, they become more or less 


412 GLACIAL GRAVELS OF MAINE. 


mixed with them, and thus a large portion of the heat is expended in 
melting ice within the crevasses and not within the tunnels. 

Other things being equal, surface melting is independent of the basal 
condition of the ice, i. e., whether the ice is submerged or not. In other 
words, the flowing of a glacier down into a body of water prevents the 
enlargement of the subglacial tunnels to the full sizes they would have 
had but for the presence of the water, while the supply of surface waters 
under like conditions is not diminished. 

An increased supply of water with a corresponding enlargement of the 
outlets implies an increase in the velocity of flow, hence increased trans- 
portation and diminished sedimentation. 

A sudden and marked decrease in sedimentation at or near a certain 
contour along 200 miles of coast implies some agency acting horizontally 
over a wide area to produce an increase in power of transportation (with 
decrease of sedimentation) below that level. 

In Maine we have such a transition at the southern ends of such of 
the gravel systems as reach nearest the coast, and thence extending for a 
few miles northward. In general there are topographical conditions favor- 
able to a somewhat more rapid rate of ice flow south of this line, but on a 
somewhat hilly and uneven coast this cause ought to result in differences 
in the elevations of the southern ends of the gravel systems. Hence, 
while it is probable that the rate of ice flow was accelerated south of the 
northern ends of the fiords (fiord line), it could have been only a contribu- 
tory rather than a controlling cause of the relatively small enlargement of 
the subglacial tunnels south of the fiord line. 

The ending of the gravels at nearly the same elevation can best be 
accounted for by supposing the basal ice to have been submerged in the 
sea to an unknown depth not exceeding, along the outer coast line, about 
200 feet below the highest level attained by the sea. 

The highest beaches along the outer coast have nearly the same eleva- 
tion above the present sea level. This is independent evidence that the 
surface of the sea, measured northeast and southwest, at the time of its 
greatest elevation was approximately parallel to its present shore, with per- 
haps a little local warping in the Penobscot Valley and in a few other 
places. If the petering out of the gravels near the fiord line was largely 
the result of basal submergence of the ice-sheet in the sea, the termination 


OSARS. 413 


of the gravels at their southern ends so near the same horizontal line could 


have been predicted and is just what it ought to be according to that 
hypothesis. 

There is independent evidence that the sea beat against the ice front, 
or at least against its base, all the time of the retreat back to the highest 
beaches. This proves a somewhat higher level of the sea during the time 
when the coastal gravels were being deposited, and is presumptive evidence 
of the presence of the sea over the present land at such a level as would 
then submerge the basal ice at the fiord line and account for the revolution 
or transition in the development of the glacial sediments that took place 
near that line. 

Thus, from whatever point of view we approach the subject, we find 
the development of the coastal gravels, according to the hypotheses indi- 
cated, presenting a connected and self-consistent series of phenomena. If 
so, a corresponding development ought to be found wherever glaciers flowed 
into the sea from regions where the conditions were such that continuous 
osars formed on the land. Probably the presence of marginal glacial lakes 
of fresh water also helped to arrest the enlargement of the subglacial 
tunnels, but perhaps not so much so as sea water. 

So complex is the problem that it can not be claimed that all the 
elements have been set forth above. 


OSARS. 


The long continuous ridges, or osars, are a feature of the interior of 
the State. They are usually continuous for only a few miles and then are 
interrupted in various ways. Where they go up and over hills the gravel 
is usually abundant on the northern slopes, while little and sometimes no 
gravel is found on the tops of the hills, especially when penetrating narrow 
passes. On steep southward slopes the gravel is often scanty or absent for 
long distances, and then at the foot of the slope large ridges or often plains 
are found. Here and there on these steep southern slopes (20 to 80 feet 
per mile) may be found small masses of bowlderets and bowlders that are 
well rounded by water. These as truly are the local representatives of the 
osar as if they formed a large ridge. It is not a definite amount of gravel 
that is necessary to form an osar or to prove where the glacial river ran. 


‘The above-named gaps in the osars appear to have a direct relation of effect 


414 GLACIAL GRAVELS OF MAINE. 


and cause to the slopes of the land. But gaps are not seldom found in the 
midst of a level plain, which we can not attribute to conditions of the land 
surface. There is no change in the slopes, nor hills to produce crevasses, 
nor narrowing of valleys. Such gaps must have been produced wholly 
by local conditions of the ice and glacial streams. Many of the osars have 
been washed away by streams, but such breaks in the ridges are not con- 
sidered as true interruptions of the system. Erosion gaps were made sub- 
sequently to the formation of the ridge, an accident having nothing more 
to do with the original form of deposition than if the gravel had been drawn 
away to build a road. The osar in this report is considered “interrupted” 
only when for some reason the gravel was not originally deposited continu- 
ously. These gaps are so short, as compared with the long reaches of 
gravel, that on the State maps they often can not be represented without 
exaggeration. When mapped, the ridges are seen to have a linear arrange- 
ment which the longest of the gaps do not obscure. If represented on a 
detailed topographical map, the close connection of the ridges would be still 
more clearly indicated. 

The ridges formed by a single glacial river, including its tributary and 
delta branches, are marked as a single system. Osars marked as tributary 
can be traced to a definite junction with each other or to points very near 
each other, where they are separated by intervals no greater than are ordi- 
narily found in the main ridges in the same region and on the saine sort of 
land surface. When osars approach each other as if they were tributaries, 
but instead one (or both of them) expands into a delta and seems to end 
before reaching the other, they are regarded as distinct systems (e. g., 
Pleasant River and Lilly Bay systems). 

The osar systems are of various lengths up to 130 or 140 miles. 
Briefly summarized, the more important facts are as follows: Their materials 
are more or less rounded, polished, and assorted by flowing water. The 
water flowed along the ridge. In most if not all cases it flowed southward, 
as is proved by the direction of transportation, by the dip of the strata, by the 
positions of the deltas, and by the fact that at the north ends of the sys- 
tems the stones are usually much less waterworn than at the south ends. 
The gravel usually rises above the land on each side. These phenomena, 
as well as the meanderings of the systems, could be produced only by 
rivers flowing between solid barriers that have now disappeared. Ice is the 


MONOGRAPH XXXIV PL. XXXII 


U. S. GEOLOGICAL SURVEY 


Ge 


as 
WWE 


DUO NI ZL 


4 
Hi 


i 


LOOKING SOUTHEAST. 


KATAHDIN OSAR, WHALESBACK; AURORA. 


The ridge rises 100 feet above Union River, shown on the left. 


The low pass by which the osar penetrates the hills is shown in the distance near the center. 


OSARS. Ald 


‘only solid that can have served this purpose. The osar rivers had tributary 


and delta branches like those of ordinary rivers. While often following 
drainage slopes like surface rivers, yet more often they traversed rolling 
plams or passed over hills from one drainage basin to another, thus freely 
disregarding the minor inequalities of the land. In only a few cases did 
they cross hills rismg more than 200 feet above the valleys on the north. 
They penetrate the hilly regions along low passes, and often take the form 
of terraces far up on the hillsides. 

Several features of the osars require further discussion. The osars 
proper are best developed in central and eastern Maine. The northern 
parts of the longer ridges are rather small and narrow and have rather 
steep lateral slopes. Standing on the narrow top, the meandering ridge 
often presents an uneven, heaped appearance, much like a moraine. Going 
southward, on the average the ridges become larger and have a more even 
surface. When within about 75 miles of the coast, every few miles enlarge- 
ments of the ridges are found which have various forms. Sometimes they 
are little tables only 200 to 300 feet wide and two or three times as long. 
These may be solid or may contain one or more shallow kettleholes. Here 
and there a hummock appears on top of the osar, rising 20 to 40 feet above 
the rest of the ridge, and at these “pinnacles” the ridge is generally broader 
than elsewhere. At one or two places within the belt of country lying 
between 50 and 75 miles from the coast, we find the osar usually divides 
into two or more ridges which after a time come together again and form a 
single ridge. They thus inclose long, narrow basins, or, when connected 
by cross ridges, rather deep kettleholes. These areas of reticulated ridges 
are not large, a mile or two in length and hardly an eighth of a mile wide. 
In this part of their courses several of the osars expand into broad, solid 
plains or massives a mile or two long and nearly half as wide. Thus, in 
Greenbush the Katahdin system twice expands into massives of this kind 
rising about 100 feet above the rest of the osar and the level plain in 
which they are situated. Their surfaces are rolling and afford some 
shallow basins, but they can not be regarded as a plexus of reticulated 
ridges in their present form. They are what such a plexus would become 
if the inclosed basins were nearly filled up with gravel so as to leave only 


shallow hollows. One of these massives thus represents a single broad 


ridge of uneven surface. 


416 GLACIAL GRAVELS OF MAINE. 


Most of the osar systems also expand at various distances from the 
coast into marine or glacial lacustrine deltas. 

When we come within 20 to 40 miles of the coast, we find in many 
cases large plains of reticulated kames. These are much longer than the 
areas of reticulated ridges found farther north. They extend from 230 feet 
up to 400 or 500 feet. At about the same distance from the coast all of 
the osars begin to become systematically discontinuous. Southward the 
ridges become on the average shorter and smaller and the intervals between 
them longer, and in all but a few cases they apparently terminate near the 
north ends of the bays of the coast and only a few feet above sea level, as 
has been stated of the discontinuous osars. 


COMPARISON OF CONTINUOUS WITH DISCONTINUOUS OSARS. 


The osars are thus seen to be somewhat discontinuous, but not system- 
atically so until they approach the coast. In almost all cases in the interior 
their interruptions have a direct connection with the slopes of the land or 
places where there would naturally be swift currents, as where the rivers 
crossed hills or penetrated narrow passes. But the discontinuity of the 
coast is very different. There the sediments are gathered more often on 
the hills, while the lowlands show no gravels. Only in comparison with 
the coastal gravels, then, are the osars continuous. 

A plausible theory of osar formation postulates that it began as a dis- 
continuous series of separated deposits left here and there in enlargements 
of the channel or other places favorable to sedimentation. As the channel 
was gradually enlarged, sediments could be deposited more and more 
frequently, until at last continuous ridges were formed. On this hypothesis 
both the continuous and discontinuous systems began in the same way, but 
the osars went on to a more perfect development. 

Elsewhere we stated numerous facts proving a gradual retreat of the 
ice and forward advance of the sea and bare land. The limited amount of 
wave erosion proves that the Champlain elevation of the sea was geolog- 
ically brief, yet it afforded time for the completion of a large amount of 
geological work. This fact rather favors the hypothesis that a continuous 
ridge begins as a series of discontinuous deposits, which gradually become 
confluent if the flow of the river is continued long enough, or at least is not 
inconsistent with it. Yet some weak points remain in the argument. 


CONTINUOUS AND DISCONTINUOUS OSARS. 417 


First. A ridge formed by filling in the gaps between shorter ridges 
ought to show the fact by its stratification. Thus far I have not observed 
stratification of this kind. To this it may fairly be answered that the 
number of accessible excavations in the osars is too small to be considered 
crucial in the case. 

Second. The assumption that the glacial streams continued to flow 
longer in the interior of the State than near the coast does not necessarily 
imply that they were employed in osar making for a longer time. Super- 
ficial streams could not begin to build osars till the melting reached the 
débris in the ice. We do not know that subglacial streams of sufficient 
size to form osars extended over all the northern osar territory during all 
the.time that elapsed between the forming of the osars near the coast and 
the final melting of the ice m the interior. This region may have been 
in the zone of superficial streams during the earlier part of this time, until 
the subglacial streams were extended northward. 

Third. When we reach northern Maine, only short ridges have thus far 
been found. It is certain that the ice lingered longer here than it did 
farther south, and it is at least supposable that an osar could be prolonged 
northward as the ice receded. Instead, the appearances are as if the regions 
of osar deposition were shifted from one place to another at the successive 
stages of retreat—that is, not by a recession of the same osar to the extreme 
northern part of the State, but by a transfer of osar forming to some other 
glacial river. The hills of northern Maine would in general not be so 
hard for osar rivers to surmount as many hills they crossed farther south. 
But it is impossible now to determine the reasons the osars were not pro- 
longed to the St. Lawrence-St. John watershed or beyond it, since we do 
not yet know all the phenomena of the retreat of the ice-sheet. It is a 
generally accepted doctrine that very deep ice invaded the Adirondacks, 
also the Green and White mountains, from the north. This could not have 
happened unless the valley of the St. Lawrence River were at one time 
filled by ice as far east as the White Mountains. In a paper read before 
the Portland Society of Natural History in 1881, I called attention to the 
apparent diminishing of the severity of glaciation northward in Maine. 
This was inferred from the increasing number of areas where the glaciation 
has not obliterated the preglacial surface of weathering, also from the 


smaller amount of attrition exhibited by the stones of the till. The latter 
MON XXXIV 27 


418 GLACIAL GRAVELS OF MAINE. 


argument would not be valid if what I then assumed to be subglacial till 
is really englacial. The scarcity of drift bowlders in some parts of eastern 
Aroostook County also points in the same direction and toward less intense 
glaciation eastward as well as northward. Recently Mr. R. Chalmers, of the 
Geological Survey of Canada, has published the opinion that in eastern 
Quebee the ice flowed northward into the Gulf of St. Lawrence. Obvi- 
ously it makes a great difference in our views of the ice-sheet that covered 
Maine whether we regard it as fed from the Hudson Bay region or by a 
névé in the upper St. John Valley that sent out glaciers north, east, and 
south. The breadth of the zones of accumulation and wastage would be 
very differently estimated in the two cases. Such a radiate flow from the 
upper St. John Valley would naturally occur during the last of the glacial 
epoch, no matter what may have been the history of the time of maximum 
glaciation. Until the St. John-St. Lawrence watershed is thoroughly — 
explored from the White Mountains northeastward, I do not feel justified in 
insisting on a local névé in northeastern Maine, at least as anything more 
than an incident of the decay of the ice-sheet, although my observations 
in Maine accord well with that hypothesis. 

Concerning the theory that a continuous osar is in all respects the same 
as one of the systematically discontinuous series in a more advanced stage, 
it must be admitted that it is somewhat probable, and yet there are reasons 
for seriously doubting its tenability. It seems to be difheult to correlate 
the two classes of deposits when there were so great differences in the 
conditions under which they were deposited. 

1. The discontinuous gravels of the coast were formed in a region that 
was at one time under the sea. At the marine deltas we have direct proof 
of subglacial rivers flowing into the sea, and the tunnels appear to have 
been below sea level. Without assuming that the subglacial tunnels were 
beneath sea level at the time either the discontinuous or the continuous 
osars were deposited, the fact that the progressive changes of sea level may 
have caused the pressure of the sea to extend farther and farther back 
within the tunnels must be allowed its full weight in casting doubt on the 
question, What would have happened in the coast region of Maine if the 
sea had not risen on the land? Before we can admit that the continuous 
ridges are only an advanced stage of the discontinuous series, and that the 


CONTINUOUS AND DISCONTINUOUS OSARS. 419 


difference is due to causes arising wholly within the ice irrespective of 
the sea, we must learn what the development of osars is beyond the reach 
of submergence, say in Nova Scotia, and show that they conform to this 
hypothesis. 

2. If, as seems probable, the deposition of sediments in the glacial 
channels was somewhat recessive, the matter of local slopes of the land 
may have been an important factor in determining the development of the 
gravels. Near the coast we are beyond the ranges of transverse hills with 
little obstruction to the flow of the ice, while northward the thinning ice 
would be more obstructed by the transverse hills, except in a few of the 
deepest valleys. It may therefore have happened that the continuous ridges 
of the north were deposited when the ice at the place of deposition was 
more nearly stagnant than when the more southern gravels were deposited. 

3. It is evident that the ice continued to flow after the transverse hills 
rose above the ice surface, for at the low cols of the hills there are in numer- 
ous places small rounded swells of till, a form of an incipient moraine, 
marking where small glaciers for a time crept over the low places in the 
hill ranges. In general these morainal ridges are small, very much smaller 
than the Waldoboro moraine. At the time the terminal overwash aprons of 
glacial sediments elsewhere described were formed the ice had retreated far 
north of two transverse ranges of hills (counting from the coast region 
backward) and the ice front was near the foot of south slopes. Here the 
motion of the ice would naturally be more rapid. The morainal ridges 
found near Katahdin Iron Works and East New Portland date from this 
period, and they are rather larger than the Waldoboro moraine. For some 
years I was not sure that these ridges and mounds were not a freak of the 
subglacial till, but my observations in the Rocky Mountains have now 
(1893) convinced me that they are moraines of englacial matter. 

We have hints here and there, then, that the rate of ice advance varied 
from time to time during the decay of the ice-sheet, according as the gla- 
cier terminated on an up ora downslope. Presumably the surface gradient 
of the ice varied also. What effect these changes would have on the reces- 
sive development of the glacial gravels remains to be determined. This 
uncertainty embarrasses our comparison of the continuous ridges of the 
interior of the State with the discontinuous gravels of the coast region. 


420 GLACIAL GRAVELS OF MAINE. 


WERE _OSARS DEPOSITED BY SUBGLACIAL OR BY SUPERFICIAL STREAMS? 


Neglecting basal melting, we divide the ice-sheet into a zone or area 
of diffused superficial waters, a zone of superficial streams, and a zone of 
subglacial streams. But these superficial streams are formed only where 
there is considerable thickness of snow and ice, near the margin of the néyé, 
and seldom if ever would englacial matter get up to such a height in the 
ice. These streams may have helped determine the courses of subglacial 
streams, but they could not have deposited glacial gravels until the ice was 
so far melted that the bottoms of their canyons approached so near to the 
ground that they found englacial matter to roll and transport. The height 
to which basal morainal matter can rise in the ice, especially in a hilly 
country, is quite uncertain, but most of the englacial matter must have 
been low in the ice. Without assuming any definite height of the englacial 
matter, we can safely affirm that if any osars were deposited by streams 
that flowed in channels open above to the air, it was when the ice at the 
place of deposition was rather thin. Such streams would not be the cor- 
relatives of the surface streams found far up toward the névé, but rather 
of those described by Russell near the extremity of the Malespina glacier, 
or by Wright near the retreatal moraines of the Muir glacier. It has been 
often assumed that those who maintain that the osars were deposited by 
superficial streams mean that they were deposited far back from the 
extremity of the glacier toward the névé, whereas, since most of the osars are 
stratified, this hypothesis postulates channels cut down through the ice to the 
ground or nearly to the ground, a condition that can occur only near the 
distal end of the glacier, where the ice is not very deep. Such supposed 
channels, open on the top to the air, might have very different antecedents. 
They might be formed by surface waters eroding and melting a channel 
downward in the ice, they might have become open to the air by the 
melting of the roofs of subglacial tunnels, or a subglacial tunnel might 
have become stopped, either by sediment or by ice, whereby the stream 
was forced to rise and overflow on the ice or form an englacial channel. 
In ease of a subglacial tunnel proving insufficient to conduct all the water, 
a portion might often run off on the surface, as happens at the time of the 
discharge of the Miirjelen See, and thus a single river might have both a 
subglacial and a superglacial outlet. Such accidents might often be facili- 


TESTS OF SUBGLACIAL OR SUPERFICIAL DEPOSITION. 421 


tated by a body of water rising above the mouth of the stream tunnel, 
such as the sea, or a glacial lake, or even the dam found on the proximal 
side of hills over which subglacial streams flow. Thus it might often 
happen that the same osar river was in different portions of its course 
subglacial, englacial, and superglacial. The important matter, from the 
geological standpoint, is to be able to recognize the deposits of these 
different kinds of streams in the field. We therefore make a preliminary 
inquiry as to the tests by which to distinguish them. 


LENGTH OF RIDGE. 


I have been able to devise no crucial test between the two kinds of 
streams depending on the length of the ridge, yet there is much to prove 
that the deposits in a subglacial tunnel are more likely to be longer and 
those in superficial channels shorter. We omit from this discussion the case 
of subglacial streams becoming superficial by the disappearance of their 
roofs, since that is a late phenomenon which happened at some time to all 
subglacial tunnels, and is of significance only when the deposit of gravel 
continued after the collapse of the roofs. 

Obviously the normal place for the subglacial river is beneath the ice, 
and the cases where it rises for a time into englacial or superglacial chan- 
nels are exceptions. Such portions of its course must be shorter than the 
subglacial. We may therefore eliminate from this comparison all except 
two cases: The rising of a subglacial river onto the surface near the ice 
front, like the kame river of the Malaspina glacier, and the case of the 
channel supposed to be wholly due to superglacial waters. 

Regarding such terminal or marginal superglacial channels as those of 
the Malaspina glacier, we must admit that the conditions under which they 
occur are unusually favorable as compared with other glaciers or known 
ice-sheets. This glacier is situated near sea level; it is so nearly stagnant 
that large areas have become covered with forest; it is in slow retreat, 
though almost fossil, and has rather steep terminal slopes. For some 
reason the glacial streams have either formed no subglacial tunnels under a 
marginal zone of uncertain breadth, or the original tunnels have become 
blocked by ice or sediment or moraines so that the streams have been 
forced to form englacial tunnels, which become superglacial by the melt- 
ing away of the overlying ice, and the streams continue such as they flow 


422 GLACIAL GRAVELS OF MAINE. 


down the terminal ice slope. If the glacier continues to retreat, it seems 
probable that a ridge or series of ridges such as are now forming and aban- 
doned channels of these rivers will be prolonged northward as far as the 
englacial channels reach. This furnishes an observational basis for the con- 
clusion that during the retreat of the ice-sheet, wherever the ice was very 
stagnant and the subglacial streams found their tunnels choked near their out- 
lets, they freely rose into englacial or superglacial channels. Since in doing 
so they would naturally wander more or less from the course of the original 
tunnel, a plexus of ridges would more often be formed than a single ridge. 

Now some of the shorter osars of Maine belong to regions lying north 
of transverse hills, where, after the hills in front were bare, the ice must 
have been somewhat stagnant and the conditions would be favorable to the 
formation of marginal ice canyons of this class. But the longer osars go 
up and over hills, and some of them occupy the longer north-and-south 
valleys, where the ice flow would be rapid and subglacial streams would be 
easily formed anywhere near the ice front. 

One other class of superficial channels in which it is supposable that 
osars were deposited is due to waters of superficial melting cutting canyons 
in the ice down to the ground. At one time I considered it a probable 
hypothesis that in a country like the interior of Maine, where the ice over- 
flowed so many transverse hills, the subglacial streams would not readily 
develop, and that here were the proper conditions for surface streams to 
continue to flow until near the final disappearance of the ice. The Mala- 
spina: glacier makes it difficult to maintain that contention. It is not admis- 
sible that there were in Maine any more favorable conditions for surface 
streams than that glacier affords, except that the summer melting may have 
been more rapid in the more southern latitude and that there was less water 
warmed on bare land to go down beneath the ice to enlarge the subglacial 
tunnels. If on so stagnant a glacier with so narrow crevasses the surface 
waters are able to find their way into the subglacial tunnels, it must be 
admitted to be improbable that large surface streams could exist anywhere 
near enough to the margin of the glacier to have reached the englacial 
matter of the ice-sheet, unless under extraordinary conditions that could ~ 
have prevailed only for a limited time and over limited areas. The con- 
clusion follows that the great length of the osars of Maine favors the 
hypothesis that they were mainly formed in subglacial tunnels. 


TESTS OF SUBGLACIAL OR SUPERFICIAL DEPOSITION. 493 


ANGLE OF LATERAL SLOPE OF THE RIDGES. 


The lateral slopes of the ridges are in general rather less steep in the 
region below than in that above 230 feet. Not only the lenticular kames 
but also the continuous ridges have as a rule rounded summits and gentle 
side slopes below 230 feet. This is partly, but not wholly, due to the 
waves of the sea washing over the tops of the ridges. Assuming that the 
lenticular eskers were formed beneath the ice and that their gentle side 
slopes are in part due to the action of the ice in flowing over them, we can 
not set up that fact as a crucial test for subglacial streams. The overhang- 
ing walls of a superficial stream may impinge on the contained gravels, and 
when these channels were greatly enlarged at the base, the contained 
gravels might have as gentle slopes as the subglacial. In the interior of 
the State some of the ridges have very steep lateral slopes, and are of 
uneven size, and show hummocky heaps like a terminal moraine. I do not 
see how we can admit that the ice flowed over these ridges since their com- 
pletion. If they are stratified at their bases, they must have been deposited 
in superficial channels, the gravel rising above the basal enlargements or 
in subglacial tunnels after the ice had ceased to flow, or nearly so. The 
test here is not infallible, but the probabilities slightly favor the superficial 


streams. 
INTERNAL STRUCTURE. 


Sediments deposited beneath the ice must be stratified unless the strati- 
fication is obliterated by the pushing forward of the sediments by the ice. 
Facts are elsewhere recorded indicating that the ice had a limited power to 
disorganize small portions of eskers on their stoss sides. In various places 
the osars appear to have lost their stratification. At one time I thought the 
Cormna-Dixmont osar had been disorganized where it crossed valleys, while 
it remained stratified on the hills. Later excavations make this doubtful. 
It is very difficult to find excavations in Maine that do not show more or 
less surface sliding, unless they have been made very recently. Seldom 
can a sand-and-gravel bed be implicitly trusted after even a single winter. 
I therefore leave out of account many cases of apparently pellmell struc- 
ture observed in the earlier years of my exploration, since my notes do 
not definitely show that the excavations had been made during the summer 
they were examined. A residue remains where osars have apparently no 


424 GLACIAL GRAVELS OF MAINE. 


stratification, yet plainly are composed of water-washed material. My 
conclusion is that where the whole of a ridge of till, from which the finer 
detritus has plainly been washed by water, has lost all signs of stratifica- 
tion and has a pellmell structure, the best interpretation is that it was 
deposited upon the ice in a superficial or englacial channel, and that when 
the ice underneath the sediment melted, the gravel slid down irregularly 
and the original stratification was lost. 

A well-marked instance of an osar with pellmell structure is Indian 
Ridge, at Andover, Massachusetts, described many years ago by Dr. Edward 
Hitchcock, and more recently and fully by Prof. G. F. Wright. Professor 
Dana has referred to this ridge as a moraine. But the material is slightly 
polished by water and the finest parts of the till have been washed out of 
it. It is not the ordinary till of the region, but the residue after a portion 
has been removed by water. There has also been some water transporta- 
tion, but not much, or the stones would be more polished. Moreover, it 
stands in substantially the same relation to the plain of stratified sand and 
gravel near Ballardvale as the osars of Maine stand to the deltas deposited 
in glacial lakes. In a sense all glacial gravels are morainal. It is not 
proved that Indian Ridge was bodily transported horizontally by the ice 
after its deposition, yet this may have happened. If so, it will be a dis- 
puted question whether to term it a moraine or an osar. The criterion of 
distinction between the till and the glacial sediments proposed in this report 
is that the one was brought to its present position by the ice and the other 
by water. In case of ice transportation of Indian Ridge as a whole, we 
would have a mingling of the two processes. But where a transported 
ridge maintained its individuality as a mass of water-washed matter distinct 
from the adjacent till, I should not hesitate to apply the term “ osar” to it. 
It is certain that few, if any, of the osars of Maine were thus bodily trans- 
ported by the ice, at least in the last stages of their development. Where 
an osar is stratified in some parts of its course and is pellmell in others, 
there can have been no bodily transportation on any theory yet suggested. 

In general we remark: A stratified internal structure is consistent with 
either subglacial or superglacial streams. Pellmell structure of a large 
mass of glacial gravel strongly favors the hypothesis that it was deposited 
on the ice, not beneath it. Quaquaversal stratification of a cone (not due 
to surface wash by the sea waves) is in favor of the theory that the gravel 


TESTS OF SUBGLACIAL OR-SUPERFICIAL DEPOSITION. 495 


was deposited by a superficial stream as it plunged into a pool beneath the 
ice, or by a stream that was wholly subglacial. 


MEANDERINGS OF A RIDGE. 


For convenience, the meanderings may be divided into two classes. 

Meanderings of the first class are deflections for several or many miles, 
such as all the longer osars and osar-plains of Maine make in order to fol- 
low valleys or to find a low pass through the range of hills. Many of the 
longer deflections along valleys are where the ice was also deflected and 
the osars are parallel to the glacial flow. Such places would be favorable 
to the formation of subglacial tunnels. Other long meanderings are found 
in level regions where the direction of ice flow would be substantially the 
same over all the plain. If subglacial tunnels were here formed, it must 
have been for a part of the distance transverse to the direction of glacial 
flow. The Seboois-Kingman-Columbia osar leaves the valley of Seboois 
River, a tributary of the Penobscot River, and takes a course for 20 miles 
southeastward over two divides to Patten. It here abandoned a north-and 
south valley, down which the ice could freely flow, for a course transverse 
to the motion of the ice. Here the course of the glacial river must almost 
certainly have been transverse to the direction of the ice flow, but often 
we are in doubt as to the direction of ice flow during the very last of the 
Glacial period. Doubtless many of the deflections then prevalent were 
never recorded, since the movements took place over land already covered 
by the ground moraine, and scratches made on rocks then bare of till have 
usually weathered away. Hence it may often be that these apparent 
deflections from the direction of ice flow are not such at all, as we should 
see could we find the record of the latest glaciation. 

I can assign no physical cause for the formation of subglacial tunnels 
for long distances in a direction transverse to the flow of the ice, except in 
regions much broken by crevasses, such, for instance, as those near the 
outer terminal moraines. This seemed likely to afford a crucial test 
between the subglacial and the superglacial streams, but uncertainties as to 
the direction of flow of the ice during the very last of the Ice period, and 
as to the power of a superficial stream to cause an extension of a subglacial 
tunnel to follow nearly its own course, have intervened. Just as we get in 
sight of a crucial test it eludes us. 


426 GLACIAL GRAVELS OF MAINE. 


Of the longer meanderings, all that can be said is that they are trans- 
verse to any known direction of flow of the ice. 

Meanderings of the second class are short—from a few rods to a large 
fraction of a mile. They are such as might be produced by either kind of 
stream. They are plainly such as would characterize the channel of a 
superficial stream. On the other hand, a subglacial stream would often 
follow a transverse crevasse for a short distance, and thus could flow trans- 
versely to the glacier. It is not certain how far it could thus find its way 
transversely. So, also, in the northward extension of a subglacial tunnel 
its course might often consist of short zigzags caused by its attempt to 
follow a superficial stream in a direction transverse to the glacier. 

In general it may fairly be urged that many of the meanderings must 
have been formed simultaneously, and that some of them must have been 
transverse to the glacier. Now, though ice is protean in its resources, it 
can not be all things at the same time. The osars of Maine skirt too many 
hillsides and cross too many valleys of natural drainage to permit the 
admission that the subglacial waters could everywhere penetrate the ice 
transversely to the direction of ice flow. The probabilities are overwhelm- 
ingly against the hypothesis. For subglacial waters to flow transversely to 
the motion of the ice must have been the exception rather than the rule in 
Maine, except near the ice front, where the ice was much crevassed. Near 
the great outer terminal moraines and in the tracts of reticulated ridges or 
kames the ice was so crevassed that probably the subglacial waters could 
make their way so as to practically follow the slopes of the land. 

The longer meanderings transverse to the direction of ice flow certainly 
add some difficulties to the hypothesis of subglacial streams. 


PINNACLES OR ELONGATED CONES. 


On the theory of subglacial streams the ‘‘pinnacles” or elongated 
cones which here and there rise above the rest of an osar can be accounted 
for as having been deposited in an enlargement of the subglacial channel, 
such, for instance, as forms at the base of the cascade where a superficial 
stream plunges down a crevasse into a subglacial tunnel. On the theory 
of superficial streams they could be explained as having been deposited in 
the broad pool that formed where a lateral tributary joined the main stream, 
or in one of the numerous pools that would form at the base of waterfalls 


a 


TESTS OF SUBGLACIAL OR SUPERFICIAL DEPOSITION. 427 


orrapids. Another way of accounting for them would be by the action of 
ice dams such as would naturally form when the spring floods began to 
break up the ice and snow that had gathered in the open channel during 
the preceding winter. As the waters poured over the dam, the unusual 
velocity would erode sediments that had previously been deposited in the 
channel, and they would be piled up a short distance below. On this 
theory there ought to be a gap in the ridge just north of the cone of gravel. 
Such gaps are found north of the “Pinnacle” at Pittsfield, also north of 
several similar enlargements of the Exeter Mills-Hermon osar. I have no 
sections showing the nature of the stratification at these places. If the 
stratification of the cones is quaquaversal, it will favor other theories rather 
than the ice-gorge theory. 

On the whole, we must conclude that the pinnacles do not afford a 
satisfactory test as to whether the osars were deposited in subglacial or 
superglacial channels. 


BROAD AND MASSIVE ENLARGEMENTS. 


Such are the so-called “mountains” of Greenbush. On the one 
theory subglacial streams poured into a gradually enlarging lake. On the 
other a very broad and deep enlargement was gradually made in the super- 
ficial channel. It is only the case of the pinnacle on a large scale. But in 
this as in many other cases the rival theories may have to compromise. 
A surface stream may have poured into a pool, like many of the streams of 
the Greenland ice, and have escaped as a subglacial stream. 

I can discover here no satisfactory test for the two theories. 


RETICULATED RIDGES. 


Reference is here made to the plexus of ridges into which an osar often 
expands. 

Superficial channels can become filled and new ones formed, as every 
river delta proves, and as we see exemplified on every hillside during the 
melting of the snow and ice in spring. A subglacial channel can also 
become clogged by sediment, and it is easy to conceive circumstances such 
that a new channel could be more readily formed than the old one could 
be enlarged. The conditions under which the reticulated ridges were 
formed will be more fully discussed hereafter. For the present I only 


428 GLACIAL GRAVELS OF MAINE. 


remark that the plains of reticulated ridges are often found im very level 
regions not favorable to the production of crevasses, except perhaps those 
of tension near the ice margin. So far the probabilities favor the theory 
of superficial streams. On the whole, the reticulated ridges can not be 
admitted as affording a crucial test. 


PROBABLE VELOCITIES OF THE TWO KINDS OF STREAM. 


In many places in the osars we find rounded bowlderets and bowlders 
in the midst of much finer material. To account for these bowlders we 
may postulate moderate currents for most of the time, with now and then 
a sudden flood; or, more often, such bowlders probably fell from the ice 
onto the gravel in the bed of a glacial stream and were rounded, not so 
much by being themselves rolled forward as by the attrition of smaller 
stones pushed past them. Such bowlders are very common in the reticu- 
lated ridges of western Maine. In these cases we need not postulate more 
rapid currents than would be necessary to move the finer matter. If we 
make proper allowance for such adventitious bowlders, obviously the size 
of the transported rocks and stones will measure the velocities of the 
currents. 

If most or all of the morainal débris was contained in the lowest part 
of the ice, as is generally believed, then the superficial streams that are 
found near the névé line, or anywhere high upon the ice, would be glacial 
torrents, but not osar-forming débris. Obviously, only those portions of 
superglacial channels that are in ice containing débris can be of significance 
in osar formation. The theory that such streams could form osars where 
the ice was deep must stand or fall with the theory that the débris reached 
high elevations within the ice. 

We need not, then, in estimating the velocities of the superficial 
streams, consider the general surface gradient of the ice, but only that of 
the marginal portion rising to the height of the englacial matter, perhaps a 
few hundred feet above the ground. Here for a few miles, say 2 to 5 
miles, we can grant to the superficial streams waterfalls, rapids, pools, and 
all other accidents of open surface channels, and velocities both greater and 
less than those due to the surface gradient of the ice. 

On the other hand, the velocities of subglacial streams are only in 
part determined by the slopes of the land. When the capacity of the 


Pe se 


TESTS ‘OF SUBGLACIAL OR SUPERFICIAL DEPOSITION. 429 


tunnel suffices to carry off the water without its rising in the crevasses, the 
velocity is chiefly determined by the land slopes, but any surplus causes 
some of the water to rise in the crevasses as into the standpipes of an 
aqueduct system. The only limit to the effective “head” in the crevasses is 
determined by the height of the tops of the crevasses over which the water 
can overflow on the surface. During the summer floods, when the supply 
of water is large as compared with the capacity of the tunnels, the water 
may often be driven by the pressure of hundreds of feet of water in the 
tunnel and crevasses. In other words, the effective ‘“‘head” of subglacial 
streams can not exceed the vertical differences in height between the mouth 
of the tunnel and the top of the nearest crevasse connecting with the tunnel, 
and therefore subject to overflow. When we come to compare the two kinds 
of stream with respect to velocity, we find a mechanism in both cases for 
producing high velocities with corresponding coarseness of sediments. It 
is doubtful whether we are able to distinguish between the two kinds of 
stream by the size of separate fragments of the sediments. 


EROSION OF THE GROUND MORAINE. 


Both kinds of stream would erode the subglacial till while in contact 
with it. A subglacial stream being necessarily in contact with the lower till 
the whole time of its flow, ought to erode it more than a superficial stream, 
which could reach it only after it had cut its way to the bottom of the ice. 

Erosion beneath the osars—T his is a difficult subject of investigation, owing to 
the character of the exposures. Artificial excavations do not go deep 
enough, and at the rivers which have eroded the osars there is almost 
always surface sliding of the gravel from above. At Pittsfield Village the 
Sebasticook River has eroded one’side of the Hartland-Montville osar and 
the gravel distinctly lies upon the bare rock. At numerous places the 
gravel near the edge of the osar overlies the till, but this may be due in 
part to surface sliding since deposition. At Clinton and various other places 
excavations show that the gravel near the axis of the ridge extends nearly 
to the rock, and then the base of the gravel was not reached. The facts 
observed are too few for generalization, but point to considerable erosion of 
the ground moraine beneath the osars. 

Erosion of the ground moraine in places not now covered by gravel— Along the courses of 


the osar rivers are many gaps in the ridges where we can now see the 


430 GLACIAL GRAVELS OF MAINE. 


former beds of these rivers. In a few places, as northwest of North Mon- 
mouth and northeast of Hogback Mountain in Montville, a ravine of erosion 
has been excavated in the till. Generally where the larger glacial rivers 
crossed the hills, or on steep down slopes, we do not find a definite ravine 
of erosion, but the till is scanty or almost wholly absent over an area several 
times as broad as the ordinary breadth of the osar. In these places there is 
less till than in the surrounding country, and we must admit a large removal 
of till, both the englacial and the subglacial. On the other hand, there 
has been but little erosion of till in several passes and on several divides 
where the circumstances would appear to be favorable to erosion. Among 
these may be named the pass south of Grand Lake on the Houlton system, 
the divide near Forest station on the Hersey-Danforth branch, the Katahdin 
system in a low pass situated just northwest of the Whalesback in Aurora, 
The Notch in Garland, and the valley of the east branch of Georges River 
in Montville. ; 

We have, then, several cases of very great erosion of the till on the 
line of the osar rivers, many cases where there has been a moderate erosion, 
and perhaps an equal number of cases where there are now no gravels yet 
there has been but little erosion of the till by large osar rivers. No posi- 
tive inferences can as yet be drawn from the observed facts bearmg on the 
question of subglacial versus superglacial streams, though the probabilities 
rather favor the superficial streams. On the theory of subglacial streams 
it is difficult to account for such facts as are elsewhere recorded as being 
observed at The Notch in Garland. While there are a large number of 
cases where the subglacial hypothesis is equally in accord with the facts, 
and in some cases better in accord with them than the hypothesis of super- 
ficial streams, there are other places where superficial streams are as 
strongly indicated by the facts. All this points to the conclusion that the 
osar rivers were in some places subglacial and in other places superficial or 
englacial. This may be bad for the symmetry of theories, but seems to be 
true to nature. 

GAPS IN THE OSARS. 

Both subglacial and superglacial streams could sweep their channels 
free from sediment at places where the channel was narrower or shallower, 
or where the slopes of the land gave unusual velocity to the current. The 
velocity of subglacial streams is certainly often much greater than that due 


TESTS OF SUBGLACIAL OR SUPERFICIAL DEPOSITION. 431 


to the slopes of the land. It is doubtful if continuity or noncontinuity 
furnishes a crucial test between the two kinds of streams, but the pheno- 
mena near the coast make it probable that noncontinuity is a distinguishing 
feature of an early stage of subglacial sedimentation. 


SIZE OF THE OSARS. 


If, as I assume, the only superficial streams (if there were any) that 
were concerned directly in osar formation were situated near the ice 
front, then the probability of such a stream forming a large ridge is not 
so great as that a long subglacial stream would form one. The only 
way such a stream could make a very large ridge is retreatally, and 
even then it is difficult to account for one, especially for the stratified osars. 
For sedimentation in the present stratified condition could not have 
begun till the ice in the bottom of the superficial channel was melted, 
and since that would happen only late, it seems improbable that a very 
large ridge could collect after that time before the ice was all melted. 
The great size of such ridges as the Whalesback, Aurora, favors the 
subglacial hypothesis. 


LOCAL VERSUS FAR-TRAVELED MATERIAL. 


Professor Chamberlin has shown that in the West the osars are com- 
posed of local matter clearly differentiated from the englacial till, which 
was derived from the distant crystalline hills. His argument is that sub- 
glacial streams would reach the local matter, whereas superficial streams 
would rarely do this, but their sediments would consist of englacial matter 
from a distance. 

Several disputed questions are involved in the application of this argu- 
ment to Maine, such as the manner in which basal débris got up into the 
ice, the angle of its supposed ascent, the height it attained, ete. In many 
places in Maine I have not been able to draw so fine distinctions as those 
of Professor Chamberlin between subglacial till of local and englacial till of 
distant origin. There are multitudes of places, especially in eastern Maine, 
where local matter appears in the upper part of the till within a few feet or 
rods from the northern edge of an outcrop of rock. This is especially 
noticeable in the case of granite bowlders. Whether this is subglacial or 
englacial till is a question for determination. I have not always been able 


432 GLACIAL GRAVELS OF MAINE. 


to distinguish them. The application of this test is not so simple as it is 
in the West. Only in eastern Maine are the outcrops such that the test 
can be applied without considerable study of the local rocks. In Enfield 
and Prospect, granite bowlderets and some bowlders appear in osars 
within much less than a mile from the north edge of a granite area— 
in fact, it may be only a few rods. On the other hand, in Aurora and 
eastward toward Deblois the water transportation has been so great that 
almost all the gravel has traveled several to many miles. This was in the 
course of the Katahdin osar river, one of the largest glacial rivers of the 
State. The law seems to be that the local matter appears in osars of mod- 
erate or small size. 

But these ridges at Enfield and Prospect are stratified; hence, on the 
superglacial hypothesis, the bottom of the superficial canyon had probably 
reached the ground at the time of deposition; and if so, would contain 
basal and local matter. The most noticeable thing about these granite 
bowlderets and bowlders is that they appear on the tops of ridges 30 to 50 
feet in height. I do not see how superficial streams can elevate bowlderets 
and bowlders, whereas the subglacial streams of the Malespina glacier do 
raise such coarse matter. If the osars were deposited by superficial streams, 
the bowlderets and bowlders in question must have been raised by ice 
movements, and when released from the grasp of the ice by the melting, 
they tumbled into the canyon. If so, they must have risen in the ice 30 
to 50 feet within a fraction of a mile, and that, too, on level ground or on 
a gentle northern slope, as in Enfield, not from the brows of crags or hills. 
This is only one of numerous instances where the superglacial hypothesis 
demands that the englacial débris should arise very rapidly in the ice and 
to considerable height. 

After making allowance for local difficulties, it appears to me that on 
the whole the sudden appearance of local matter in the smaller osars and 
to such a height in the ridges distinctly favors the hypothesis that the osars 
were formed by subglacial streams. At one time it seemed to me incredible 
that the subglacial streams could raise bowlderets, and especially bowlders, 
against the force of gravity. Anyone who has doubts on this subject can 
have them all removed by inspection of the device for placer mining termed 
the hydraulic elevator. 


! 


TESTS OF SUBGLACIAL OR SUPERFICIAL DEPOSITION. 433 


PHENOMENA OF GLACIAL RIVERS IN CROSSING HILLS AND VALLEYS. 


As before noted, the hills of Maine are in large part transverse to the 
direction of glaciation. Hence the courses of the longer glacial rivers very 
often led them up and over hills. On the steeper down slopes the behavior 
of subglacial and superglacial streams would, perhaps, not be very unlike, 
but in the valleys and on the northern slopes of hills their action might 
be quite different. The osars are in the main stratified, and the only 
superglacial streams here referred to are those the bottoms of whose can- 
yons had reached the ground at the time of deposition of the gravel, or so 
nearly that the stratification was only obliterated locally, if at all, during 
the unequal melting of the subjacent ice. This I conceive could take place 
only in the marginal region near the ice front. Some distance back from 
the front a superglacial channel might contain sediment, if the englacial 
débris reached so high as the ice, but it would overlie such deep ice that 
if left in this condition the unequal melting of the subjacent ice would 
usually confuse the stratification. It is not assumed, except for the sake 
of argument, that such streams helped to deposit the osars. 

We first suppose a subglacial tunnel to cross a transverse valley and 
hill, as in the accompanying diagram, fig. 32. The water in the tunnel 
below the horizontal line 
AB touching the top of 
the hill will form a dam 


or lakelet and be in equi- 
librium, like the water 


Fie. 32.—Ideal section of glacial stream channels crossing transverse valleys. 
EBC, glacier; ABD, subglacial stream; B, C, transverse hills. 


of a sewer trap. Water 
will rise to the same level in all crevasses opening into the tunnel. As fast 
as water flows from the north into the trap an equal amount will flow 
southward over the hill at 6. The general law of velocities in the tunnels 
is that if the tunnels increase in capacity from north to south at an equal 
ratio with the increasing supply of drainage waters, other things being 
equal, the velocities will be uniform throughout the whole courses of the 
tunnels. But there are at least two causes for the tunnel being smaller in 
the valley than elsewhere—that is, relatively to the supply of glacial waters. 

First. The depth of ice, and presumably the rate of inward flow of the 


tunnel walls, is greater in the valley at D. 
MON XXXIV 28 


434 GLACIAL GRAVELS OF MAINE. 


But then the inward flow of the walls is antagonized by the outward 
pressure of the contained water. Also in Maine no glacial rivers are 
known to have flowed over hills higher than 200 to 250 feet, except in one 
extreme case of 400 feet, measured above the valleys lying to the north of 
them. This represents only one-fifteenth to one-twentieth of the maximum 
depth of ice. If we assume so great plasticity of the ice that so small a 
difference in thickness could make much difference in the sizes of the sub- 
glacial tunnels in the two situations, it seems difficult to account for very 
deep crevasses or subglacial channels. On the whole, it seems improbable 
that so small differences in thickness of ice would much restrict the enlarge- 
ment of the subglacial tunnels in the valleys; yet it might to some extent. 

Second. It will be seen that the basal ice north of the hill is perma- 
nently bathed in cold waters, and that the crevasses also are filled to the 
same height as the top of the hill. All the waters of local melting that 
pour into the crevasses in this part of the tunnel must more or less become 
mixed with the cold waters of the crevasses, and their heat will largely be 
expended in melting the walls of the crevasses, not in expanding the tun- 
nels, just as has been pointed out in the case of a glacier flowing down into 
the sea. Now some of these dams or permanent bodies of subglacial water 
must have been several, perhaps many, miles in length. Thus the subglacial 
dam north of Springfield, in the course of the Seboois-Kingman-Columbia 
osar river, was at least 15 miles long, and that of the Portland system north 
of North Woodstock extended as far as Andover, a distance of 20 miles. 
Because of the greater subsidence toward the north, the length would at 
that time be somewhat greater than now. The ice would be many years 
in passing over such distances, and the cumulative effects of such dissipa- 
tion of the energy that otherwise would help to enlarge the tunnels must 
have been considerable wherever the courses of the glacial rivers were so 
nearly parallel to the ice flow that the same body of basal ice m its progress 
was thus continuously modified for a term of years. 

We aie therefore justified in assuming that in the longer valleys situated 
north of hills crossed by the glacial rivers the subglacial tunnels would 
be small relatively to the supply of water, and the velocities would be 
rather high during all the earlier stages of ice-channel sedimentation. Ridges 
deposited at this time would be rather narrow and composed of coarse 
material. Indeed, the sedimentation might often be of the discontinuous 


TESTS OF SUBGLACIAL OR SUPERFICIAL DEPOSITION. 435 


type, the streams in places having velocity sufficient to clear their channels 
of sediments. 

Later, when the ice became thin and could no longer flow up the hill, 
this stagnant condition would favor the enlargement of the tunnels in spite 
of the interference of the basal waters. When the ice surface sank to the 
top of the transverse hill, or near to it, the stream could no longer escape 
southward over the hill. It would then escape transversely to the east or 
west along the top of the ice or between the ice front and the hill, or by 
transverse subglacial channels. But in most cases the rivers crossed the 
hills by passes leading up to low cols, and the hills at the sides of these 
valleys would hold in the stream till the ice had melted back to the north 
ends of the passes. The retreat of the ice from the tops of the divides back 
to the northern ends of the passes might occupy several or even many years, 
and during all this time there would be a marginal body of water between 
the ice and the top of the col, absorbing heat direct from the sunlight. This 
water would most rapidly extend itself northward along the line of the sub- 
glacial river, partly through mechanical erosion and the heat of the stream 
waters and partly because the ice near the tunnel would already have become 
somewhat honeycombed by melting within the crevasses above the tunnel. 
Thus the frontal lake would be narrowly V-shaped, extending deeply into 
the ice, as an enlargement of the original tunnel, expanding toward the 
south till it passed beyond the ice front and extended across the whole 
valley or pass. Into this deltoid body of water the glacial river poured its 
sediments. The coarser matter was left near the mouth of the subglacial 
tunnel, and thence the sediments would grow finer obliquely outward. If 
the lake became very broad as compared with the size of the river, we might 
even have a delta deposited in it like that in Unity and Thorndike, or in 
Dover, northwest of The Notch, Garland. If so narrow that the velocity 
of the current was less checked, an osar terrace or broad osar would be 

“deposited in the marginal lake, like the terraees that border the Whalesback 
in Woodstock, Milton, and Rumford. In the lake or within narrower ice chan- 
nels near its northern end, a plexus of reticulated ridges might be deposited. 
The development of these broad-channel or lacustrine sediments would go 
on retreatally northward till the ice front receded to the north ends of the 
passes, when the waters might or might not be diverted into new courses 
back of the ice front, but in any case the stirface of the marginal lake began 


436 GLACIAL GRAVELS OF MAINE. 


to sink to lower level. The suddenness with which the development of the 
eravels was often arrested and the absence of transition beds laid down in 
transverse channels or of terraces between the end of the ice and the hills 
that rose in front of it, may perhaps be best interpreted as proving that the 
ice sometimes became so greatly shattered near the front that the waters 
spread outward and often transversely in a multitude of small delta branches, 
none of which were large enough to deposit gravels in the short time that 
elapsed before the ice was all melted in that region. The nature of the 
development of the glacial sediments during the retreat of the ice down the 
northern slope and thence back to C (fig. 32, p. 433) would depend on many 
conditions, and we might expect many different manifestations. One of the 
critical points, so to speak, is at the northern end of the permanent water 
trap at C. At the time of diminished flow in the fall and winter the stream 
would no longer fill its tunnel and more or less sediment would drop where 
it entered the permanent water trap ABD. Now and then this might result 
in the channel being clogged during the floods of the succeeding summer, 
forcing the waters to rise, and causing the formation of an englacial or super- 
ficial channel and the opening of a lake at the place where the stream rose 
on the surface or flowed down again after passing the obstruction in the tun- 
nel. In such a lake broad ridges or an osar-plain might form, or reticulated 
ridges, but not a delta, unless it was very large compared to the river. Or 
the broad channel or lake might be extended continuously across the valley, 
perhaps by the confluence of a number of lakes that origmally formed in 
the course of the channel. When the waters forced a transverse passage 
north of the hill early enough to permit considerable enlargement and depo- 
sition of gravels, we have the phenomenon of delta or diverging and trans- 
verse branches like the intricate reticulations of the gravel systems of 
southwestern Maine. Here the rocks are mostly granitic and the till is very 
abundant. This must have favored the clogging of the subglacial tunnels 
and the digression of the streams to new channels that often diverged widely 
from the original channels. 

We next consider what is conceived to be the probable behavior of a 
superglacial stream in the same situation, i. e., during the retreat of the ice 
over a valley situated north of a hill crossed by an osar system, premising 
that it must be able to deposit stratified osars, and hence that the bottom 
of its canyon must reach the ground or nearly to it. At first the bed of the 


TESTS OF SUBGLACIAL OR SUPERFICIAL DEPOSITION. 437 


stream lies approximately parallel to the ice surface #B. As the ice melts, 
the bed will come to oceupy the position of the dotted line and dip beneath 
the horizontal line 4B. A marginal lake will form in front of the ice, just 
as in the supposed case of a subglacial stream. The melting will be most 
rapid along the bed of the stream and near the mouth where it enters the 
lake, and thus the form of the lake will probably not differ much from that 
when a subglacial stream flows into it. In this broad channel or lake we 
might have reticulated ridges or an osar-plain deposited. As the ice 
retreated toward the bottom of the valley it would seem that the glacial 
gravel ought to be more abundant in that region than anywhere on the 
northern slope. It certainly would be so, and of frontal or ovyerwash char- 
acter, unless the superficial stream forms a glacial lake at some point 
toward the north, which arrested the transportation of sediments from the 
north. We can admit transverse escape over the ice to the east or west or 
around the front of the ice next the hills, but not subglacial or englacial 
escape, since this would be inconsistent with the supposed conditions, i. e., 


SHEPMAN. SPRINGFIELD. 
P 


M A 


Fic. 33.—Section of valley between Sherman and Springfield. M, at Macwahoc; K, at Kingman; P, at Prentiss. 


ice so stagnant that the crevasses were not sufficient to enable a subglacial 
tunnel to be formed. This is a large demand to make so near the ice front, 
but my purpose is to give the theory every possible chance to account for 
the field phenomena. 

These general principles have been discussed with a view to their 
application to certain localities. 

The great Seboois-Kingman-Columbia osar system descehds the valley 
of Molunkus Stream from Sherman to Kingman, where it crosses the Mat- 
tawamkeag River nearly at right angles, and then ascends the other side of 
the Mattawamkeag basin, through Webster, Prentiss, and Springfield, where 
it crosses a divide near 200 feet higher than the river at Kingman. This 
great osar river has left gravels for 40 miles or more north of Kingman, 
where it crossed the deep transverse valley of the Mattawamkeag. Fig. 33 
represents the system in this part of its course. The slope of the Molunkus 
Stream is moderately steep from Sherman to Macwahoc; then the valley 


438 GLACIAL GRAVELS OF MAINE. 


is nearly horizontal to Kingman, and thence the slope rises moderately 
steeply again to Springfield. From Sherman to Macwahoe, and again 
from Prentiss southward, the gravel takes the form of a broad osar, or osar 
terrace, of sand and rather fine gravel. At Macwahoe and Prentiss it 
expands into complexes of reticulated ridges melosing kettleholes and com- 
posed of coarse gravel, cobbles, and bowlderets. For 3 or 4 miles near 
Kingman the system takes the form of a narrow osar of rather fine sand, 
and is somewhat interrupted. It is the narrowness and fineness of this 
ridge near the bottom of the transverse valley that specially demands 
explanation. The noncontinuity is m part, and possibly may be wholly, 
due to postglacial erosion. On both theories there were broad osar chan- 
nels north of Maewahoe and south of Prentiss. Both postulate a lake- 
like expansion at Macwahoce, and another at Prentiss, in which or near its 
margin was left a plexus of reticulated ridges. On the subglacial theory 
the tunnel would be relatively small where it crossed the transverse valley, 
and sedimentation scanty or in narrow ridges. This corresponds well with 
the osar at Kingman, but for a long time I had difficulty in accounting 
for the fineness of the sediment. Now Macwahoe and Prentiss are not far 
from the same elevation, and only 3 miles or so from opposite ends of the 
subglacial dam. During the retreat a broad channel was formed north of 
the divide in Springfield, which extended itself as far north as the complex 
in Prentiss. North of there the sediments were scanty or absent until the 
lake or broad channel was opened at Macwahoec. If the opening of this 
lake was due to a clogged channel, the water may have overflowed later- 
ally, so that the old channel was never thereafter used, except for local 
drainage, and thus only sand would be deposited. But as the channel was 
not permanently clogged, the coarse sediment from the north would mostly 
stop in the lake at Macwahoc and only the finer pass on across the valley 
to gradually fill the old tunnel or parts of it just preceding the time that the 
ice retreated so far north that the tunnel was disused. On the superglacial 
theory the order of events must have been substantially the same. The 
opening of the lake at Macwahoe and deposition of the plexus of reticu- 
lated ridges is essential to both theories. But the distance between the 
complexes of Macwahoc and Prentiss is about 10 miles, and we must sup- 
pose deposition in one began immediately after the other was ended, or 
there would be an osar-plain or other body of retreatal gravels left over the 


TESTS OF SUBGLACIAL OR SUPERFICIAL DEPOSITION. 439 


lower parts of the Mattawamkeag Valley near Kingman. This enlarges 
our claims for superglacial osar rivers from small streams near the ice front 
to the long osar rivers themselves. 

Thus we here discover no crucial test between the two rival theories, 
though the difficulties of the superglacial hypothesis are increased with 
every complication, such as that involved in the claim of their ability to 
form glacial lakes in which stratified gravels were deposited, and hence must 
have reached to the bottom of the ice, or nearly, and that, too, at a distance 
of 10 miles back from the ice front. It is a matter of observation that pools 
which presumably would expand into lakes in a time of stagnation of the 
ice movement are formed in Greenland where large surface streams flow 
beneath the surface and escape subglacially, but no instances are recorded 
where they form very deep lakes and escape superficially. 

Tn all cases known to me where the osars went up and over rather high 
hills with long valleys to the north, such as the Portland system north of 
North Woodstock, the Smyrna series north of Danforth, the Bridgton series 
north of Baldwin, the north end of the Peru-Buckfield system, and others, 
the field phenomena prove that the gravels of earliest deposition north of 
the higher hills were deposited in rather narrow tunnels and that the streams 
had considerable velocity. There are several cases of reticulated ridges on 
the northern (up) slopes, which may, perhaps, be accounted for on either 
theory. Where broad osars or lake deltas are found in such situations they 
are plainly a rather late if not a retreatal phenomenon. 

A sufficient cause, as it appears to me, has been pointed out for the 
restriction of the subglacial tunnels north of these hills, but I know of none 
on the superglacial hypothesis. At Kingman we may perhaps account for 
the absence of broad-channel phenomena by the convenience of the broad 
channel or lake at Macwahoe, but in other places there is no such way of 
accounting for the lack of broad-channel deposits in the valleys north 
of hills. 

On the whole, I conclude that the subglacial hypothesis is strengthened 
and the superglacial weakened by the behavior of the glacial rivers where 
they crossed transverse valleys and hills. 

It is not here meant to assert that all the broad osar channels date from 
so late a period of the ice-sheet as that assumed in this discussion. 

It must be admitted that the various tests for distinguishing in the 


44() GLACIAL GRAVELS OF MAINE. 


field between osars deposited respectively by subglacial and superficial 
streams are not so definite as is desirable. Probably all the field phenomena 
can be accounted for on either hypothesis, though sometimes only by 
cumbrous complications that in the end must break down any hypothesis 
that has to resort to them. Often in the last fifteen years I have discov- 
ered what was hoped to be an unmistakable and crucial test, only to find 
my quest unsuccessful. 

Some of the elements of the problem of the osars have been set forth 
above. It remains to correlate them with others in order to get a more 
general view of the osars, their history and causation. This is reserved 
for a subsequent chapter. 


BROAD OSARS OR OSAR TERRACES. 


Several of the osars, after preserving the form of a two-sided ridge 
with arched cross section for a distance of 5 to 30 miles from their north 
ends, expand into a level-topped plain varying in breadth from one-sixteenth 
to three-fourths of a mile. These plains or terraces contain no kettleholes 
proper, though the surface is sometimes gently undulating. More often it 
is very level. The material of the plain is usually rather fine gravel and 
sand. In some cases they are found as terraces on hillsides far above any 
ordinary stream, and can without difficulty be at once pronounced as of 
glacial origin. But they often extend across the whoie of the valleys m 
which they are situated, and so closely resemble valley drift that they can 
with difficulty be distinguished from that form of alluvium. The principal 
tests for distinguishing the two kinds of sediments are the following: 

1. Topographically, the broad osars occupy the same position with 
respect to the osars lying north of them as they would if they were depos- 
ited by the same glacial rivers. The existence of the osar north of them 
indicates that a glacial river flowed from the north to the poimt where the 
osar expands into the broader plain. This river must be accounted for. It 
could not disappear except in a lake or the sea, or by flowing out of the ice 
into a valley where the ice had already melted. But the osar terrace is not 
a delta proper, showing a complete transition from the gravel to sand and 
finally clay. It was not deposited in a lake proper or in the sea; at least the 
velocity of the water was only partially checked. The glacial river must 


BROAD OSARS OR OSAR TERRACES. 44] 


therefore have continued in a channel confined wholly or in part by ice, or 
it flowed into a valley over which the ice had melted all the way to the sea. 
In the last-named case the sedimentary plain is a frontal delta, and ought to 
extend continuously down the valley to the level of the sea as it existed at 
the time of deposition. If at any point the sedimentary plain in question 
leaves the valley in which it was deposited and takes a course on the hill- 
sides or passes over hills into another drainage basin, we have proof of the 
continuity of the glacial river sediments over even the lower parts of the val- 
ley where for a time they were found in form so much resembling valley drift. 
The sediments here termed “ osar terraces” cross hills and valleys just the 
same as the osars, and these topographical relations are inconsistent with the 
hypothesis that they are valley drift, though in the valleys their situation 
is such that they must since deposition have been subject to the action of 
streams and often have been eroded by them, and often were overlain with 
valley drift. If an osar-plain were confined wholly to a single valley we 
should have no topographical test to distinguish it from valley drift. This 
does not apply to the osar-plains of Maine. | 

2. The material of the beds of ordinary streams in every part of the 
State I have visited has been carefully examined with a view to determining 
the amount of attrition to which the existing stream gravel has been sub- 
jected. Everywhere the testimony of the gravel of the osar-plains, when 
compared with that of the adjacent streams having the same slopes and size 
of drainage basin, is substantially the same. The average shape of the 
gravel of the osar-plains shows immensely more waterwear than the gravel 
of the existing streams. The proofs of this are abundant and overwhelm- 
ing. Only in the mountain regions where the slopes are 100 or more feet 
per mile do the stones in the beds of streams show rounded forms at all 
comparable to those of the glacial gravels. 

3. The quantity of the broad osar sand and gravel is usually much 
greater than the valley drift of the adjoining regions. 

4. Many of the osar terraces do not extend across the whole of the val- 
leys in which they are situated, and show no tendency to expand into a delta 
at a broad part of their valleys, but sometimes end at one or both sides in 
a well-defined bluff rising quite abruptly above the level of the adjacent 
land. At such places we must grant they were bordered by ice walls, or 
the alluvium would have spread obliquely outward across the valley. 


442 GLACIAL GRAVELS OF MAINE. 


While the sediments of broad osars are prevailingly finer than that 
of narrow osars, yet these plains show decided variations im coarseness 
of material in different parts of their courses, just as the osars do. Thus 
the great Portland system on a north slope in Rumford and Milton consists 
of fine gravel and a large amount of sand. Approaching the top of the 
divide at North Woodstock, we find gravel and cobbles, while on the south 
slope from North Wood- 
stock past Bryants Pond 
to North Paris it consists 
of pebbles, cobbles, bowl- 
derets, and many bowlders 2 to 4 feet in diameter, all very much waterworn. 

In many places the osar-plains have been much eroded by small 
streams and boiling springs. Invariably the erosion has been most rapid 
toward the sides of the plain, leaving a central uneroded ridge resembling 


Fic. 34._Diagrammatic section across osar-plain; Woodstock and Milton. 


an osar in external form. In some cases the central ridge is composed of 
much coarser material than the ground on each flank, but I have not been 
able to find sections satisfactorily showing the nature of the stratification of 
the central and lower parts of the ridges. At the tops of the ridges and in 
the plain at their sides the strata are nearly horizontal, or somewhat cross- 
bedded, dipping a little toward the south. 

Fig. 34 shows a section across the osar-plain in Rumford and Milton. 
The central ridge is here known as the ‘‘Whalesback,” and has about the 
same height as the uneroded terraces at 
the sides of the valley. 


Fig. 35 shows a section across the Fie. 35.—Diagrammatie section across osar-plain; valley 
valley of Bog Brook in Canton and a Renee 
Livermore. The broad osar has here been eroded by two brooks, one on 
each side of the central ridge, and they flow in opposite directions. The 
central ridge here rises several feet higher and the material is much coarser 
than the terraces of sand and gravel that are found on each side of the 
valley. 

There must be a reason why the central ridge invariably resists erosion 
better than the matter at its sides. In most cases the ridge is plainly com- 
posed of much coarser matter. I have found no sections showing that an 
ordinary narrow osar with arched cross section lies along the axis of the 
osar-plain, though this is probably the case where the central ridge rises 


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BROAD OSARS OR OSAR TERRACES. 443 


above the terraces. But the broad osar can easily be differentiated into 
the following tracts: (1) An axial belt of coarse composition and with the 
material very much waterworn. (2) Bordering terraces, .ometimes not so 
high as the central ridge, composed of finer materials and often not so much 
waterworn. 

These facts point to the followig interpretation: that first there was 
an ordinary narrow osar channel in which more or less coarse gravel 
accumulated, and that as the channel subsequently broadened the original 
osar was more or less washed away and incorporated with the growing 
marginal terraces. ‘These conclusions are strengthened by the fact that in 
several cases an osar expands for several miles into a broad osar and sub- 
sequently narrows again into the ordinary osar type of ridge. The broad 
osar or osar terrace is thus seen to differ in no essential character from the 
narrow osar except that it has advanced a stage farther in its development. 
The history of this development was in part as follows: 

First there was an ordinary narrow osar river. Whether this had 
begun to deposit gravels within its channel previous to the great enlarge- 
ment of the channel is to be determined in each case separately, for these 
rivers appear to have had different histories. We need not here inquire 
whether the narrow rivers flowed in subglacial vaults or in superficial can- 
yons open to the air. The flow of water increased, and so gradually that 
the ice at the sides of the origimal channel could be melted and eroded 
at a corresponding rate. I defer the question whether the enlargement 
took place retreatally. While the channels remained comparatively narrow 
only coarse matter could be dropped in them, and as the channel widened 
the central osar was more or less washed away and spread laterally into the 
sides of the broadening channel. The broader the channel the finer the 
sediments that were deposited in it, unless there was a corresponding increase 
in the supply of water. It is due to a gradual broadening, accompanied by 
rapid currents, that the central osar is not abruptly differentiated from the 
bordering terraces of finer sediments. 

Were the broad osar channels roofed with ice? Two facts can be 
named as especially bearing on this question. 

1. The rarity of till on or within the broad osars. 

In the northern part of Baldwin are a number of bowlders very little 
if in any degree polished by water, yet situated upon and within the sand 


444 GLACIAL GRAVELS OF MAINE. 


and fine gravel of a broad osar. They are exceptional, and the question of 
their origin is discussed elsewhere. 

In general we find in the broad osar terraces no unpolished stones or 
bowlders that can be regarded as till dropped from the roof of an ice arch, 
though near the borders of these plains the stones have received much less 
attrition from water rolling than have the stones of the osars or central 
parts of the broad osars. 

2. The great breadth of the terraces. 

If the broad osar channels were roofed with ice, the size of the ter- 
races demands ice arches of great lengths of span, numbers of them up to 
one-fourth of a mile, several one-half of a mile, and a few three-fourths of 
a mile. These would be very long spans for bridges of high-grade iron 
and steel. If the arches sagged and were supported on the gravels or on 
abutments of ice, we ought to find the terrace uneven on its surface, with 
kettleholes and reticulated ridges. The sizes of the subglacial channels 
would be so restricted, too, that only coarse sediment would be deposited 
all the way out from the central ridge to the margins. We now and then 
find reticulations and hummocky ridges in the midst of osar terraces that 
may have had such a history, but the broad osars proper are very level in 
cross section and contain such fine sediments that they must have been 
deposited in large channels where the flow of the water was moderate. 

The interpretation of these facts is further discussed below. 


FORMATION OF THE BROAD OSAR CHANNELS. 


Among the methods whereby the ordinary osar channel might become 
broadened, we may mention the following, premising that these channels 
had somewhat parallel sides: 

1. Subglacial channels were enlarged laterally and subglacially to the 
full breadth of the channel. ' 

This theory would require us to assume that the larger bowlders, at 
least over most of the State, were contained in the basal ice. For the broad 
osar is composed, as a rule, of rather fine material, and does not carry 
bowlders such as ought to have fallen from the roofs of so broad tunnels if 
the englacial bowlders were high in the ice. 

The difficulties of this hypothesis are very great if not imsuperable. 


FORMATION OF BROAD OSAR CHANNELS. 445 


The breadth of these broad channels (one-eighth of a mile to one-half mile 
or more) is such that it seems inadmissible to postulate ice arches of such 
dimensions without their roofs collapsing. Russell reports the roof of a 
stream of the Lucia glacier collapsing. This stream is about 150 feet wide. 
Now, although the subsidence of the roof in this case appears on the ice 
surface only so long as the roof is not very thick, it by no means follows that 
there is not also an inward flow of the roof and walls with increasing depth. 
But the roofs of the broad osar channels would be from ten to twenty times 
as broad as this stream of the Lucia glacier. To postulate self-supporting 
roofs is an enormous demand. I do not see even one feature of the gravels 
or any property of ice that warrants the assumption. Locally we can con- 
ceive of such arches floating on the slack water north of hills crossed by 
the osar rivers, but the broad osars are also found on southern slopes where 
there could be no slack water. 

; Perhaps the principal question involved in the problem is this: Where 
are we to find the supply of heat necessary to melt and enlarge such great 
channels? For I assume that melting is a greater cause of enlargement 
than erosion. The channels in which were deposited the broad osars, the 
osar bowlder clay, the narrow marine deltas, also the lake-like enlarge- 
ments in which were deposited the peculiar formation elsewhere named 
‘lacustrine massives,” are all a connected series of phenomena. Any com- 
plete theory must account not only for these very broad channels but also 
for the narrow ones. If we assume that the broad osar channels were 
formed subglacially, we may as well assume that lacustrine massives 5 to 
10 miles long and 1 to 2 miles wide were also formed subglacially. But if 
we assume that these very broad channels were subglacial, how are we to 
account for the narrowness of the osars proper? Ordinary subglacial 
streams depend for the heat with which they enlarge their tunnels chiefly 
on waters of superficial melting, slightly warmed before the plunge down 
the crevasses. This supply of heat is small and only moderately enlarges 
the tunnels. - This accounts for the narrowness of the earlier tunnels. We 


‘Nat. Geog. Mag., vol. 3, p. 107, May, 1891. “‘The course of the stream below the mouth of 
the tunnel may be traced for some distance by scarps in the ice above, formed by the settling of the 
roof. Some of these may be traced in the illustrations. When the roof of the tunnel collapses so 
completely as to obstruct the passage, a lake is formed above the tunnel, and when the obstruction 
is removed the streams draining the glacier are flooded.” 

This description refers to the tunnel by which the stream descends beneath the ice after having 
risen to the surface and flowed a mile and a half on the ice. 


446 GLACIAL GRAVELS OF MAINE. 


can assume that during the decay of the ice-sheet this enlargement went 
on at a somewhat uniform rate, so that at last they attained the dimensions 
of the broad osar channels. But if so, how can we, on the subglacial 
hypothesis, account for the discontinuous gravels, where the channels con- 
necting the successive lake-like enlargements were so narrow and the 
resulting velocity was so great that for long distances no sediment was 
deposited? Besides, wear of surface streams ought to enlarge the channels 
somewhat uniformly—that is, produce ordinary osar channels; but I see 
no method of wear by which these extraordinary local enlargements would 
be produced. 

On the other hand, if we postulate a body of water open to the sun- 
light, we at once find a sufficient local supply of energy to produce these 
local enlargements, in the heat absorbed directly from the sun by the water 
of the channel, pool, or lake. We are also saved from a self-destructive 
assumption of so great power of the ordimary superficial waters of the 
glacier—such as are exposed for only a short time to the sun and then 
plunge beneath the ice—in enlarging their channels, as would make it 
impossible to account for the narrow tunnels. 

On the subglacial hypothesis the broad osar channels originated as 
ordinary narrow osar rivers, the roofs of whose tunnels subsequently dis- 
appeared. Were these, then, superficial streams? In my earlier writings 
they were so interpreted, and formed one of the principal arguments for 
the belief that superficial streams were able to cut canyons down to the 
bottom of the ice and deposit stratified sediments within them resting on 
the till or rock. Professor Chamberlin suggests that they were neither 
subglacial nor superficial. It is probable the water that flowed in them was 
in other portions of the glacier a part of the subglacial drainage. They are 
in general equally consistent with either the subglacial or the superglacial 
hypothesis, and therefore must certainly be withdrawn as evidence of 
superglacial streams. On the subglacial hypothesis all tunnels at some 
time lost their roofs, but these are supposed to have lost theirs before osar 
deposition was completed. 

2. Another hypothesis would be about as follows: ” 

As the subglacial tunnels attained considerable breadth, and the ice 
became thin, sagging or collapse of the roofs became more rapid and the 
cross section of the tunnel became a more and more flattened arch. In 


FORMATION OF BROAD OSAR CHANNELS. 447 


process of time the middle of the arch might rest on the previously depos- 
ited osar, where there was one, but in any case there would often be more 
enlargement of the tunnel laterally than in height. Where the course of 
the glacial river was approximately parallel to the ice flow, the slow set- 
tling of the roof of the tunnel would continue to modify the same mass 
of ice in its progress for a term of years and cause a somewhat continuous 
depression of the surface. In this depression or valley surface waters 
would collect and melt more or less ice before reaching a crevasse. Many 
conditions, such as the extension of the névé line northward, might cause 
an increased supply of waters with flooding of the subglacial tunnels. 
Collapse of the roof or clogging of the channel would cause the water 
to rise into englacial or superficial channels, and the latter would follow 
the depression caused by the settling of the roof and often cause the forma- 
tion of temporary surface lakes. Where the waters rose im crevasses or 
went down again into them after passing an obstruction, deep pools would 
form if the overflow was long continued or often repeated. When one or 
more pools were formed or openings were made through the roofs, the 
heat of the sun would be absorbed in increasing amount by the subglacial 
waters, the separate pools would gradually become confluent in a contin- 
uous channel open above to the sun, and this channel would then rapidly 
broaden till it sometimes came to extend across a whole valley. Many of 
the conditions for oversupply of water as compared with tunnel capacity 
would depend on purely glacial conditions, such as rate of melting, rate 
of ice flow, ete. When the falling of a.single block of ice into a tunnel 
may have changed the course of a glacial river overflowing on the ice 
into a new valley in the ice surface, it will not be expected that we shall 
be able to trace all the accidents of broad-channel formation. North of 
hills crossed by the osar rivers this process was probably often, perhaps 
always, assisted by the pool of slack water there collected, and here the 
enlargement may have often proceeded as the extension of a fringing or 
marginal lake formed north of the hill. 

This hypothesis, postulating the change in the development of an 
osar system from a narrow to a broad osar and again to the narrow 
type, demands that we shall not regard the broadening of the channel as 
extending recessively northward. Rather it took place locally, leaving 
reaches of narrow osar in the course of the same system. We can admit a 


448 GLACIAL GRAVELS OF MAINE. 


considerable enlargement as taking place at the base of the crevasse where a 
superficial stream pours beneath the ice; but I do not see how we can admit 
local supplies of ordinary superficial waters in such quantities as would 
account for the disappearance of the roofs. The overflow theory postulates 
known processes, and seems to be sufficient for the work accomplished. 
Local stoppages of the tunnels here and there would cause the local disap- 
pearance of the roofs, with the consequent broadening of the channels. 

When we come to apply the hypothesis to the enlargement of the 
narrow marine delta channels and those of the border-clay channels that 
were beneath the sea, we find special difficulties. The ebb and flow of the 
tide and the temperature of the sea would introduce new elements into the 
analysis, but their quantitative significance is uncertain. 

Applying these principles to both the up and the down slopes of the 
land as we go south along the courses of the osar rivers, I have failed to 
find any constant relation between the land slopes and the enlargements of 
broad osar channels, at least such as would warrant the prediction of their 
occurrence at particular places or slopes. If there is such a rule it is that 
in most cases a broad osar extends for some distance north of the tops of 
hills crossed by the osars. On the steeper down slopes there may have 
been the same broad channels, but quite often no gravel was left for 1 to 3 
miles south of the hilltops, and we have only inferential evidence of the 
breadth of the channel. Also the alternation of broad-channel deposits 
having a horizontal surface in cross section with the area of reticulated 
ridges will require more detailed study before correlation of these deposits 
with topographical features can be asserted. Indeed, they may often have 
had no connection with the land surface and have depended on ice condi- 


tions alone. 
RETICULATED ESKERS OR KAMES. 


In external appearance these uneven and hummocky complexes, which 
show an endless variety of ridge and hollow, are perhaps the most remark- 
able of all the deposits left by the glacial rivers. They afford all grada- 
tions of complexity from the simple branching of a ridge into two ridges 
which soon come together again, up to the great plexus 3 or 4 miles broad, 
its surface covered with a jumble of heaps, mounds, cones, and ridges, 
inclosing all forms of hollows, funnels, hopperholes, kettleholes, basins, and 


MONOGRAPH XXXIV PL. XXXIV 


— 


U. S. GEOLOGICAL SURVEY 


PA AAT aw) 

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RETICULATED KAMES; FORTER. 


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Srey! 


RETICULATED ESKERS OR KAMBES. 449 


‘Roman theaters,” many of which are so deep as to inclose lakelets without 
visible outlets. 

Probably the phenomena of all the glaciated countries will have to be 
compared before we are able to explain these interesting formations in all 
their details. ¢ 

The most important facts concerning the reticulated ridges are the fol- 

lowing: : 
1. Their geographical distribution. The most remarkable of these 
plains are situated in southwestern Maine, where they are connected with 
the Conway-Ossipee kame plains of New Hampshire. Almost all the osars 
and other gravel systems here and there expand into a plexus of reticulated 
ridges, but they are not large except in the granitic areas. The granite 
outcrops of eastern Maine are much smaller than those of western Maine, 
and the general slope of the land is not so steep. For these and perhaps 
other reasons the reticulated eskers of that part of the State do not cover 
so broad areas. . 

2. Their relations to long gravel systems. The reticulated kames are 
not a distinct class of systems, but a peculiar form into which the longer 
gravel systems here and there expand. They were deposited by the same 
glacial rivers that left the osars and other types of gravels. 

3. Their relations to relief forms of the land. All the longer gravel 
systems at some part of their course pass from one basin of natural drain- 
age to another, and most of them do so repeatedly. In the interior of 
the State the areas of reticulated ridges into which the osars and broad 
osars expand are rather small. ‘They are situated variously with respect to 
the slopes of the land, being found on both up and down slopes and in 
level regions. ‘Thus going up and over the hills and across the valleys, the 
great river at last penetrated all the higher transverse ranges of hills along 
the low passes and came out into a region of broad valleys which soon 
merge into the sea-border plain, a rolling region extending 30 to 40 miles 
from the sea. In the hill country the gravels usually take the form of osars 
or osar terraces, but when they reach the broad valleys of gentler slope 
they expand into great plains or tracts of reticulated ridges. These are 
mostly situated between the contours of 230 and 500 feet. 


4. The forms of the ridges. In western Maine the ridges are usually 
MON XXXIV 29 


450 GLACIAL GRAVELS OF MAINE. 


rather narrow at the north end of the plexus, and have rather steep lateral 
slopes. Going southward we find the ridges on the average becoming 
higher and correspondingly massive till we arrive within a few miles of the 
contour of 230 feet. The ridges then grow broader as we still go south- 
ward, the lateral slopes more gentle, and the hollows shallower. In the 
more level country of eastern Maine there is an analogous but less-marked 
change of form. 

5. Their relations to marine deltas of glacial origin. All the deltas 
left by glacial streams in the sea, both the broad, fan-shaped deltas deposited 
in the open sea and the narrower ones left in bays or broad channels of the 
ice, end at the north in reticulated ridges inclosing kettleholes and other 
basins of various sizes and shapes. 

6. Their relations to lacustrine deltas of glacial origin. Numbers of 
deltas were deposited by glacial streams in lakes inclosed wholly or in part 
by ice. In the larger of these the deltas are more or less reticulated 
toward their northern extremities. 

7. Their relations to overwash or frontal deltas of glacial origin. In 
the interior of the State, as the ice retreated northward it often happened 
that the glacial streams poured out from the ice front into valleys sloping 
southward. ‘Their sedimeuts spread out and filled the valleys like the sedi- 
ments of Alpine glaciers. Their stones have been worn and rounded by the 
glacial streams more than they could have been worn by ordinary streams, 
and often they were carried farther by the glacial streams than by the river 
of the open valley beyond the ice front. Yet at the place of final deposition 
the water was in no way confined by ice and was practically an ordinary 
river. These overwash or fluviatile deltas of glacial streams sometimes show 
a rolling, uneven surface with shallow hollows, but no deep kettleholes or 
conspicuous reticulations, except in the valley of the Androscoggin River 
between Gorham, New Hampshire, and Gilead, Maine. The character of 
the alluvium of this valley is elsewhere described. 

8. The material of the reticulated eskers. In general, the kame mate- 
rial is coarser in the hilly regions and becomes finer southward. In the 
western part of the State the reticulated ridges contain multitudes of bowl- 
derets and bowlders, many of them much rounded, others with only a 
little polish, as if carved by sand and gravel without having traveled far. 


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FORMATION OF RIDGES OF AQUEOUS SEDIMENT. 451 


All over the State the reticulated ridges are usually rather coarse. In 
western Maine the ridges transverse to the general course of the glacial 
river are on the whole rather finer in material than the ridges parallel with 
the course of the river; but this rule is not universal. Indeed the reticu- 
lated kames seem to defy all rules. 

9. Their internal structure. Many of the reticulated ridges, especially 
near the north end of the plexus, have the steep slopes and roof-like top 
characteristic of the pellmell ridge. All the excavations in Maine which I 
have examined show more or less distinct stratification. No very distinct 
layers can be expected where the materials are very coarse, and the thick- 
ness of the beds formed by a single flood might be many feet. 


WAYS IN WHICH A RIDGE OF AQUEOUS SEDIMENT CAN BE FORMED. 


1. Subaerially, in the way in which streams carrying much sediment 
build up delta channels. Thus, the Mississippi River, the Po, etc., near 
their mouths are flowing on top of a ridge composed of their own sediments. 
This ridge is really composed of two ridges which form the banks of the 
stream, but when the amount of sediment is great the ridges coalesce at the 
bottom and the river flows in a depression on the top of a single broad 
ridge. They seldom rise very high before the stream abandons the old 
channel and makes for itself a new one at the side of the old, thus spread- 
ing out in the well-known fan shape. 

2. Wholly within channels of the ice, either subglacial or superficial, 
the subsequent melting of the ice leaving the sediments rising above the 
adjacent ground. 

3. At the sides of rapid streams where they enter comparatively still 
water. A good modern instance of this kind of ridge may be seen at 
Kingman (see p. 98). This is, in fact, only a subaqueous example of 
the same process as that by which a subaerial stream in its delta builds up 
two-sided channels. The rapid glacial streams, both subglacial and super- 
ficial, would form large ridges on each side of them as they entered the sea 
or a lake. This is well exemplified by the gravels near East Monmouth 
(see p. 189). 

4. When a small stream bearing much sediment entered a body of 
still water, the two ridges formed at the sides would soon coalesce at the 


452 GLACIAL GRAVELS OF MAINE. 


bottom, and then the stream might, under favorable circumstances, build 
up a single ridge having a shallow channel on its top, an exaggerated sub- 
aqueous form of the ridge built above the sea by rivers at their deltas. 
The buoyancy of the water would enable such a ridge to have much 
steeper slopes than if formed above the water. As a glacial stream under 
these conditions entered the sea or a lake it would naturally, as the flow 
became less rapid in autumn, fill up the channel or channels in which it 
had previously flowed, so as to leave the ridge with a broad flattish or 
uneven top, or sometimes even rounded. If such a ridge were beneath the 
sea, the subsequent action of the waves would round off the summit to the 
lenticular or rounded form. 

5. A ridge forms in the lee of an island, rock, mass of ice, or other 
obstruction situated in the midst of a sediment-bearing stream. Such a 
ridge has previously been described as forming in the Presumpscot River 
below a bridge pier. 

All the above cases are instances of the general property of running 
water to drop its sediments as its velocity decreases. The distance to which 
the glacial rivers could extend ridges after issuing from the mouths of their 
channels depended on the size and velocity of the rivers. At Litchfield 
Plain the different ridges become confluent and are lost in the sand plain 
within one-fourth of a mile, and at the small marine delta in Amherst the 
sand passes into clay within the same short distance. On the other hand, in 
the larger deltas it is 3 to 5 miles northward from where the ridges become 
confluent to where they plainly were deposited in ice channels. It is diffi- 
cult to determine the line between the ridges deposited in the sea in front 
of the ice and those within channels near the margin, if for no other reason 
than that the ice must have been retreating while the delta was forming 
and the one formation would follow and overlie the other in the retreat. 
If this retreat was for any great distance, the later sands ought to overlie 
the earlier gravel ridges deposited near the ice front of the earlier times. 
Thus far I have found no field evidence of such an order of deposition, 
and it is doubtful if we can admit more than 1 to 3 miles of retreat while 
the larger deltas were in process of formation. In addition to the retreat 
of the ice front, we have to consider also the possibility that the sea was at 
the same time rising or falling. 


U. S. GEOLOGICAL SURVEY MONOGRAPH XXXIV PL. XXXVI 


A. KETTLEHOLE IN MARINE DELTA; NEAR MONROE VILLAGE. 


B. LAKE BORDERED ON ALL SIDES BY TERRACES OF GLACIAL GRAVEL; HIRAM. 


The place where the lake is now situated was probably occupied by an island of ice when the gravel was deposited, 


Shrew 


RETICULATED ESKERS OR KAMES. 453 


FORMATION OF KETTLEHOLES AND OTHER BASINS INCLOSED BY RIDGES 
OR BY PLAINS OF AQUEOUS SEDIMENTS. 

I. Such hollows or basins may be formed above sea level. 

1. In the channels of glacial streams either above or beneath the ice. 
This could happen if the streams branched like rivers at their deltas and 
subsequently came together again, or became connected by cross channels, 
thus inclosing islands of ice or covering the ice to an unequal depth with 
sediment. 

2. In case glacial sediments are deposited on the ice and in process of 
the unequal melting part of the sediment slides one way and part another, 
or settles in channels of streams. 

3. In the process of delta formation where a number of streams are 
each building up its own ridge. These streams as they radiate outward 
will here and there meet or approach one another and their respective ridges 
will inclose basins. 

4. By unequal fluviatile erosion of previously deposited sediments, 
such as the deep pools in the beds of streams at the base of rapids or 
waterfalls. 

5. By subterranean waters in the form of boiling springs. As the 
waters boil upward’ they carry off the finer matters of the soil in suspen- 
sion, and even the matter contained in solution may in time come to have 
geological importance. In some cases small lake basins may have been 
formed in this way, such as those near Fryeburg and in the upper Kenne- 
bee Valley. 

6. By the unequal filling of previously existing channels. The half- 
moon lakes of the delta of the Mississippi River are instances of this class, 
and perhaps some of the small lakelets of the alluvial plain of the Kennebec 
River between the Forks and Embden have the same origin. 

7. By ice dams. Before ice gorges give way streams sometimes shoot 
out through them with sufficient velocity to erode deep holes in the valley 
alluvium. During the flood which accompanies the breaking of the dam, 
sediments are sometimes deposited over heaps of ice, and the subsequent 
melting of the ice blocks leaves a hollow where the thickest ice was. 

II. Such hollows or basins may be formed beneath relatively still water. 

1. By glacial streams flowing into a lake or the sea. Judging from 
the ridges formed below the dam at Kingman, each stream issuing from the 


454 GLACIAL GRAVELS OF MAINE. 


ice into the still water would form a ridge on each side of it, and these 
lateral ridges would be connected by a cross ridge at a distance from the 
mouth of the stream depending on the size and velocity of the stream, the 
depth of still water, the size of the transported stones, etc. This transverse 
ridge is due largely to the whirl of the water where the swift water enters 
the still water. If a number of parallel streams of different sizes entered a 
body of still water, the transverse ridges would be formed at different dis- 
tances from the mouths of the streams. The result would be the same if 
a stream abandoned its former channel for a new one. As the ice melted 
and the ice front receded, new transverse ridges would be formed from time 
to time. Perhaps it would describe the phenomena better to state that the 
two lateral ridges bend their courses so that they unite, rather than to use the 
term ‘‘cross ridge,” as if this ridge were distinct from the lateral ridges, for 
it is only a deflection of them, formed in a curve on the outside of the whirl 
where the swift water is checked and set to whirlme by the mutual action of 
the still and the rapid water. 

When small glacial streams build up each its own delta ridge beneath 
still water, the radiating ridges may approach one another and thus inclose 
basins. 

2. By glacial streams in ice channels beneath the level of compara- 
tively still water. This would more often happen in case of subglacial 
streams. The method would be substantially the same as when basins are 
formed above the sea. 

3. In the lee of a broad obstruction situated in the midst of a flowing 
stream. Bars of gravel extend from each side of the obstruction, which 
curve convergently so as to leave a crescentic basin between the coalescent 
bars and the obstruction. I have seen such basins in the lee of small islands 
in the salt-water fiords and inside ‘‘rivers” along the coast. In case of 
elacial rivers entering lakes or the sea, this may have been an important 
condition for the forming of basins. 

4, By the unequal filling of subaqueous henna The shifting bars of 
the Western rivers must often leave portions of partly filled channels as deep 
pools, which would become kettleholes or other-shaped basins if raised 
above water. The terraces of valley drift are in general very level on the 
top, showing that they were deposited under very different conditions from 
those of the reticulated ridges on the alluvial plain of the Androscoggin 


MONOGRAPH XXXIV PL. XXXVI 


U. S. GEOLOGICAL SURVEY 


A. BASIN CONTAINING LAKELET IN THE MIDST OF A BROAD GRAVEL PLAIN, NORTHERN PART OF WINDSOR 


B GRAVEL MESA; SOUTHERN PART OF CHINA 


The cirque contaning the trees was not eroded; the gravel was deposited in practically its present condition 


ORIGIN OF GLACIAL GRAVEL COMPLEX. 455 


River above Gilead or the channel of such a river as the Platte, if it could 
be drained dry. 

5. Where large quantities of sediment are being carried downward by 
a rapid stream, transverse bars naturally form across the stream, in which 
the grains or stones that are behind pass to the front, one after another, like 
the grains in a dune of blowing sand or in a ripple-mark. Bars of this 
kind, so far as I have observed them, are not large enough to be consid- 
ered the correlatives of the large transverse ridges so common among the 
plains of reticulated kames. 

The influence of tides in causing the formation of ridges and hollows 
by checking the glacial streams has not been formally included in this 
list, since it is doubtful how far tidal influence was felt by them. Yet the 
tides may in certain cases have had some effect of this kind. The tides 
would help to a horizontal stratification of the finer sediments. 

In 1878 I suggested in the American Naturalist’ that certain ridges 
that project like tongues from the side of the alluvial plain of the Andros- 
coggin near the line between New Hampshire and Maine were due to the 
overflow of the river in time of flood into a lateral valley containing a lake 
during high water. It is still a question whether there is not a particular 
size of sediment fragments which, with a proper depth and velocity of 
stream, will tend to form an uneven bed covered by shifting bars and hol- 
lows, while if the fragments become smaller than this the stream will fill 
up the inequalities of its own production and flow over a level plain. The 
drift of the upper Androscoggin Valley is perhaps the key to this problem, 
if one only knew how to use the key. 


ORIGIN OF THE GLACIAL GRAVEL COMPLEX AND ITS RELATION TO MARINE 
AND LACUSTRAL DELTAS.? 


PLEXUS SITUATED AT ONE END OF A MARINE GLACIAL DELTA. 


Here there is a gradual horizontal passage of sediments from coarse at 
one end of the delta to fine sand and finally clay, all having the same level 
as the adjacent beds. At the end where the coarser sediment is, the plain 


‘Note on the Androscoggin glacier, Am. Naturalist, vol. 14, pp. 299-302, 1880. 

>The theory that the kames were deposited in the sea was enunciated in a paper by Prof.N.S. 
Shaler, in Proc. Boston Soc. Nat. Hist., vol. 23, pp. 36-44, and to Professor Shaler.is due the credit 
of first publication. My own views were worked out independently by a study of the ridges formed 
below dams, as elsewhere described. 


456 GLACIAL GRAVELS OF MAINE. 


is always uneven and contains kettleholes and basins of various depths. 
Sometimes a few kettleholes or hollows in what would otherwise be a rather 
level plain are all the signs of reticulation that we find. Here the ridges 
are so broad and plain-like as to obscure their origin as reticulated ridges. 
Where the reticulated ridges are best developed there is a pretty regular 
gradation in the forms of the ridges. At the landward side of the delta, 
usually the north and northwest, the: gravel is coarse and the ridges are 
high and have rather steep lateral slopes. The basins are correspondingly 
deep, and the transverse ridges are well defined. As we go away from the 
place where the mouths of the glacial rivers were the ridges become 
broader, though still with arched cross section. Soon the ridges are so 
broad as to be plain-like, and so nearly coalesce that the kettleholes are 
only shallow hollows, and there is a gently undulating plain of fine gravel. 
When the area of sand is reached, the plain becomes nearly level on top 
and shows hardly a trace of separate ridges. The stratification is here 
nearly horizontal, and so continues into the region of clays, where all signs 
of the separate ridges are lost. The broad osars sometimes pass into marine 
deltas by only a few reticulations (as in New Gloucester; see pp. 227-228). 

1. The existence of glacial potholes and the phenomena of the non- 
continuous gravels prove that subglacial streams existed in the coastal 
region, and that they were concerned in osar formation, as has previously 
been pointed out. 

2. But glacial marine deltas occur in the course of the osars as a reg- 
ular part of their development, sometimes more than once in the course 
of a single river. They mark epochs in the history of the osar rivers, 
showing where the ice front stood at particular epochs. They are thus 
retreatal phenomena, not changing the character of the rivers in any way, 
but merely the conditions of sedimentation. If the discontinuous gravels 
were deposited by the subglacial rivers, so were the marine deltas. Here 
there can be no compromise between the rival subglacial and superglacial 
hypotheses. Superglacial streams must account for all the coastal phe- 
nomena, including the deltas, noncontinuity of deposition, decrease in 
quantity toward the south, the petering out of the streams near the northern 
’ or fiords of the coast, the lenticular shape of the 
gravel masses, the underlying terminal moraines, etc., or they must be 
ruled out of the coastal region altogether, except in the subsidiary form of 


ends of the ‘rivers’ 


ORIGIN OF GLACIAL GRAVEL COMPLEX. 457 


overflow channels where the subglacial streams found their tunnels closed 
and were forced for a time to rise into englacial or superglacial channels. 

3. The heaviest burden that the superglacial hypothesis has to bear is 
the basal character of almost all the kame and osar drift. By far the 
greater part of the glacial gravels is stratified and shows no sign of having 
been deposited on ice, where it would have to fall. as the ice melted. It 
has the appearance of having been deposited on the ground where we now 
find it, and this is the natural place for subglacial deposits. It remains to 
be proved that superglacial streams can cut canyons or enlarge lakes so 
deep that they penetrate to the bottoms of the ice, except near the ice 
margin, where crevasses are strongest. This reasoning, however, applies 
only to deposits within channels in the ice. Beyond the ice front the delta 
ridges of both kinds of streams would manifestly rest on the till or rock 
and can be accounted for by either hypothesis. 

4, Some of the marine deltas are very broad at their northern ends, as 
in the northern part of Alna, where one ends in a broad transverse bar or 
ridge showing no horizontal assortment of sediments from the center toward 
the ends. In other places there are two or more short ridges projecting 
here and there toward the north, as if several streams, not one, had con- 
tributed to the formation of the delta. But these deltas are a part of an 
osar system, and except in these places we have no signs of more than a 
single glacial river. All this is easily accounted for on the subglacial 
hypothesis, since those streams can force new channels when their old ones 
are blocked, or they can rise into englacial or superglacial channels. But 
how can a single superglacial stream, after cutting a channel down or nearly 
down to the bottom of the ice, wander into other channels parallel to the old 
one, all of them also cutting to the bottom of the ice, which was consider- 
ably below sea level and only a short distance back from the ice front? 
The supposed superficial streams would sometimes have to cut 100 or more 
feet beneath sea level, and yet abandon these channels for others, unless 
we suppose that there were more than one superficial stream tributary to 
the delta; but elsewhere in the course of the gravel system we have proof 
of only a single river. The broad osar channels, including the retreatal 
channels and lakes north of hills, the massive plains or mounds deposited 
in glacial lakes, also the osar border clay, all point to a rapid enlargement 
of a glacial-stream channel or a pool when once they became open to the 


458 GLACIAL GRAVELS OF MAINE. 


sunlight. This makes it all the more difficult to account for the wanderings 
of a single superglacial river when it has cut a channel to the bottom of 
the ice, or nearly so, and that, too, very near the ice front. The narrow 
marine delta could, perhaps, sometimes be accounted for on the superglacial 
hypothesis, for the melting would probably be most rapid near the mouth 
of the main river, thus prolonging a narrowly deltoid bay or channel back 
into the ice and open to the sea in front. Ice gorges might possibly bar a 
superficial channel so as to cause an overflow into a new channel, but it is 
difficult to suppose that a dam of loose blocks would last long enough to 
enable a new channel to be cut to the bottom of the ice. If we assume 
that the channel became blocked by the coarsest sediment where it entered 
the sea, what are we to do about the sediment at the distal end of the delta, 
which evidently went over this supposed bar on its way south? 

On the whole, the difficulties of the superglacial hypothesis are greatly 
increased by the breadth of the northern ends of some of the marine deltas 
and the certainty that they were enlarged, not by radiate transportation in 
the sea beyond the ice front, but by a single glacial river issuing from the 
ice by several mouths, the more distant being a half mile or more from each 
other. How far the flow of these different streams was simultaneous, and 
how far successive, is left an open question. 

Usually marine deltas are a part of the discontinuous portions of osars; 
hence often there are intervals to the north of them without gravels. Here 
we have the same problem of noncontinuity as in the case of the other dis- 
continuous deposits. Some of the deltas, perhaps, began as massive bars or 
mesas in gradually enlarging glacial lakes into which the sea subsequently 
advanced as the ice front retreated, after which time the deltas proper were 
deposited. 

5. Were all the reticulated ridges at the landward ends of the glacial 
marine deltas deposited in the sea? 

As above noted, there are sometimes gaps in the systems north of the 
deltas. In these cases I conceive that the rapidity of the streams was here 
sufficient to keep their channels free from sediment. These conditions 
probably prevailed all the way to the ice front, and in such cases all the 
reticulated ridges were formed in the sea. 

But where long ridges extend northward from the proximal anik of the 
deltas, especially complexes continuing up to considerable heights above 


ORIGIN OF GLACIAL GRAVEL COMPLEX. 459 


the highest level of the sea and for 20 miles or more, as happens in south- 
western Maine, the gravel was undoubtedly being deposited in stream chan- 
nels in the ice at a distance back from the front at the same time the deltas 
were forming. While the delta was forming the ice would be retreating, 
and the retreat of the ice would uncover the ice-channel ridges, to be at 
once covered by gravels poured out by the glacial streams which now 
flowed into the sea at some point northward. In these cases I infer that 
ice-channel and frontal ridges are both represented in this class of marine 
deltas. The case would be still more complicated if the delta began as a 
glacial lake or broad channel deposit. The history of each delta is to be 
deduced from the local conditions, and probably in the various delta com- 
plexes we have every variety and combination of ice-channel sedimenta- 
tion, with that which takes place in bodies of water in front of the ice. 
RETICULATED RIDGES AT THE PROXIMAL ENDS OF THE GLACIAL LACUSTRINE 
DELTAS. 

Elsewhere are described what appear to be lake deltas at East Brown- 
field, in North Shapleigh, in Unity and Thorndike, in Dixmont, in Newburg, 
and in other places. Two or three are possibly below the highest level of 
the sea and may be marine, or partly marine. All are north of hills, where 
fringing lakes would be formed during the retreat of the ice down the 
northern slopes. I see no points bearing on their origin other than those 
applying to the marine deltas. 


RETICULATED RIDGES AS A PART OF GLACIAL LACUSTRINE MASSIVES. 


These are the massive or solid mounds and mesas of coarse’ sedi- 
ments, showing little horizontal assortment, which I assume to haye been 
deposited in gradually enlarging lakes within the ice. They sometimes 
contain hollows or kettleholes and basins, inclosed by broad, flattish-topped 
ridges or plains.” Some of the basins may have formed where the gravel 
was deposited over masses of ice or around ice islands. If deposited on 
the ice, I infer that the gravel would lose its stratification during the melt- 
ing of the ice. More often probably the basins in this class of gravels are 
unfilled portions of the lake, left where broad reticulating ridges failed to 
coalesce completely. This sort of sedimentation would result from the 
stream pouring into the lake from different points, either simultaneously 
or 1m succession. 


460 GLACIAL GRAVELS OF MAINE. 


RETICULATED RIDGES WITHIN ICE CHANNELS. 


Near Dover South Mills the Moosehead Lake osar divides into two 
branches, each not more than 100 to 250 feet wide at the base. They 
continue a few rods apart for about a half mile southeastward, when they 
unite to form a single ridge which presently expands into a broad, almost 
delta-like plain of sand and gravel near The Notch. Both ridges have 
rather steep slopes on each side, and they inclose a long, narrow hollow or 
ravine. 

I have before described the three small gravel plains in the northeastern 
part of Monmouth. They are about one-fourth of a mile, or somewhat 
less, in diameter. Hach is crossed by a central ravine flanked by terraces 
about one-eighth of a mile wide. My interpretation is that here a rapid 
stream flowed into a small glacial lake, dropping its sediment on each side 
and leaving the ravine where its bed was. Can we apply this interpreta- 
tion to such a case as that at Dover South Mills? 

If a body of still water existed at each outer flank of tie two ridges, 
there ought to be a broad flanking terrace on each outer side; if swift 
streams, there ought to be two parallel ridges outside of the two existing 
ridges. The outer flanks of each ridge must, therefore, have been flanked 
by ice, and we are compelled to suppose that a single swift river flowed 
through the central hollow or ravine, dropping a ridge on each side, and 
its size and velocity were such for half a mile on a gentle up slope that it 
was able to keep its channel clear of sediment while building up ridges on 
each side from 10 to 30 feet in height. Now in Monmouth the central 
ravines, which I infer mark the beds of the streams, are not more than 20 
feet deep in any place, and generally are rather less than 10; their length 
is only half that of the ridge in Dover, and the beds consist of gravel; hence 
in the process of deposition it is evident that the streams built up a plain of 
sediment beneath them, though the finer sediment passed out obliquely into 
the bordering lake. In Dover the ridges are in places confluent at their 
bases, but at the deeper hollows the ravine goes down to the till, or nearly. 
I leave the interpretation an open question until other cases are examined. 

At the Whalesback, Aurora, we have two and sometimes three ridges 
extending for 3 miles or more, and nearly parallel. In places the hollows 
between the ridges are filled with gravel nearly to the top of the ridges; in 


RETICULATED RIDGES WITHIN ICE CHANNELS. 461 


other places they are so broad and deep that they contain lakelets and must 
reach very nearly to the till. If we suppose that the central parts were 
kept clear of sediment by swift streams, these transverse bars of gravel 
connecting the main ridges are still to be accounted for. 

In southwestern Maine we find in the complexes large steep-sided 
ridges extending for long distances (1 to 3 miles) without noticeable change 
in average size and without becoming confluent, except by occasional trans- 
verse bars or low ridges and many terraces. The contrast in structure 
between the ridges of the delta, which become broader and more confluent at 
their bases and show horizontal classification of sediments, and the ridges 
of the large plexus, which show little assortment of sediments but continue 
for miles of nearly uniform sizes and with steep lateral slopes, is very great 
indeed. The delta plexus is an intelligible formation; why should not all 
these ridges broaden toward the south and become finer in composition if 
they were all deposited in the sea or other large body of water? Think of 
the enormous rivers required to flow between two ridges 50 to 100 feet high 
and one-fourth of a mile apart and yet keep the space between them so 
clean of sediments that the deeper hollows are 100 feet deep, alternating 
with transverse bars rising almost to the tops of the lateral ridges; and all 
this, too, without the ridges broadening or the sediments becoming finer 
southward over distances as great as the breadth of the reticulated plexus 
of even the largest marine delta. The theory that the reticulated ridges 
were formed by unequal deposition in open bodies of water accounts well 
for the plexus at the proximal ends of marine or lacustral deltas, and for 
some of the reticulations in lakes or broad channels relatively small to 
the flow of the river, where there was no horizontal classification of sedi- 
ments, or only an imperfect one, but it breaks down in face of the larger 
complexes and those not connected with deltas, such, for instance, as those 
occurring in the course of the osars on northern slopes and at considerable 
distances from the sea. Here the reticulated ridges were often as plainly 
deposited between ice walls as were any of the osars. 

Let us now take the case of the most complex and best-developed 
plains of reticulated ridges to be found in the State—those lying west of 
the Saco River in southwestern Maine. They are situated in a region where 
the rocks are mostly granitic and the till is consequently abundant. The 
country is hilly, hence probably favorable to the englacial till getting up 


462 GLACIAL GRAVELS OF MAINE. 


into the ice to considerable distances. The region is crossed by two series 
of valleys nearly at right angles. The principal streams flow eastward 
along one series of valleys, and their lateral tributaries How north or south 
in the other series. The larger gravel series extend from north to south, 
and thus are constantly going up and down hills, crossing the east-and-west 
valleys, or following up the north-and-south valleys to a divide and then 
descending into another drainage basin. Many of the cols they cross are 
more than 200 feet higher than the land to the north. For 20 or 25 miles 
the channels of these glacial rivers would for about half their length be 
filled with slack water on the northern slopes and in the lower parts of the 
valleys. 


As we trace the gravels southward we find them occasionally taking 


the form of a broad two-sided ridge with arched cross section, but for most 
of the distance they have either the form of the broad osar terrace or that of 
the plexus of reticulated ridges. These different developments alternate with 
each other in the course of the same gravel series, proving that they were 
the work of a common river and are merely different types of sedimenta- 
tion. Toward the south the hills become lower and the valleys broader. 
Here the plains of reticulated ridges widen and become the prevailing type 
of gravels; yet here and there are small delta-plains m the midst of the 
kame complex or at their flanks, while here and there the gravel forms 
level plains—osar terraces. Often in this district the central ridge of the 
plexus is very massive, rising 50 to 100 feet above the smaller ridges that 
cover the plain at its flanks. The lateral slopes of the ridges are here 
rather steep and the kettleholes so deep that in the forest they are very 
dark and gloomy. Many of them are more than 100 feet deep. Still 
going southward, we find on the average the ridges becoming broader, 
lower, and more plain-like, while the kettleholes become shallow. Not 
far above the contour of 230 feet the ridges become confluent, as an 
undulating plain, which toward the south becomes more and more level 
and the material becomes finer until it ends in a sand plain which in turn 
passes into sedimentary clay. The belt of transition between the con- 
spicuously reticulated ridges and the plains of marine clay varies from a 
half mile up to 2 or 3 miles. In the narrower north-and-south valleys the 
gravels more often take the form of the osar terrace than the plexus of 


eee 


ORIGIN OF LARGER COMPLEXES. 463 


reticulated ridges, and when the latter is present the reticulations are not 
so complex as in broad valleys or on level plains. The problem of the 
reticulated kames is, then, closely related to that of the broad osar. In 
the one case a single channel became very much enlarged and a continuous 
plain of rather horizontally stratified gravel was deposited over the bottom 
of the whole broad channel. In the other case the sediment took the form 
of a series of two-sided ridges, more or less confluent by their bases or by 
cross ridges. And there are in a few cases transition forms between the 
two types, as of a terrace or plain having a wavy surface. Furthermore, 
the same glacial river could in different parts of its course deposit both 
these forms. We must infer, then, that no special amount of water, or of 
increase or decrease in quantity of flow, was needed. The process depended 
not upon the stream so much as upon the ice and the other conditions of 
sedimentation. ‘These conditions are so numerous that it can with some 
confidence be affirmed that the details of the process would vary in different 
localities. 
ORIGIN OF THE LARGER COMPLEXES. 

The general process by which the larger plains or complexes of reticu- 
lated ridges were formed appears to be about as follows: 

North of these plains are regions of steep average southward slope. 
The rapid streams GQnostly subglacial in southwestern Maine) brought down 
great quantities of sediment from the north. As they reached the more 
level country their velocity became less and the coarser sediment was 
dropped. In the case of the broad osar channel the deposit of sediment 
did not proceed faster than the lateral enlargement of the channel and no 
new channels were formed. A broad, rather level and continuous plain 
was deposited across the whole of this channel, which was often as broad as 
the plexus of reticulated kames adjacent. If the water could flow into and 
through this broad channel, producing a level plain, not an uneven plexus — 
of ridges, how can we admit that the reticulated ridges were deposited in a 
body of open water as broad as the osar channel? The osar-plain or ter- 
race, it seems to me, is the answer to our questions as to what would happen 
in a single. gradually enlarging broad channel—not a jumble of ridges, but 
a rather horizontally stratified plam. The evidence here distinctly favors 
the hypothesis that the ridges of the complexes under discussion are not 


464 GLACIAL GRAVELS OF MAINE. 


such as were formed at the sides of swift streams entering a body of rather 
still water, and where the hollows between the ridges represent portions of 
the channels in which the rivers flowed or unfilled parts of the surface 
which was then coyered by open water. Here the ridges were in greater 
part caused by the filling up of channels formed between ice walls, and the 
hollows and basins represent ice which separated the different channels or 
lay beneath the sediments as they were dropped. The following discussion 
assumes that these plains of steep-sided reticulated ridges, except as they 
pass into marine or lake deltas, were formed between ice walls in most 
cases. The gist of the problem lies in accounting for the formation of so 
many new longitudinal and transverse channels. Some cause must be 
adduced for the streams acting in this manner here at the reticulated kame 
tracts, while elsewhere they got along with only a single channel. 

All the field phenomena, as we have seen, favor the hypothesis that 
there were rapid streams and consequently great transportation from the 
regions lying north of the great complexes of reticulated eskers. So also 
all the causes of sedimentation combine to retard the streams and cause 
deposition at the areas of reticulated ridges. Many of them were in the 
region of backwater north of the hills. The slopes were less steep than 
farther north. The subglacial drainage had been extended north over the 
area in question, and many of the subglacial channels had come to be very 
large. During each fall and winter the existing channels would become 
more or less clogged with sediment brought down from the steeper slopes. 
A time would come when the stream would no longer be able each summer 
to sweep away the débris accumulated during the preceding cold season. 
At the time of the spring floods the water, under great pressure from 
behind, would collect in the tunnels. If it found transverse and longitudi- 
nal crevasses reaching deep down in the ice, it would follow them laterally, 
and thus in course of time a new subglacial channel would be formed par- 
allel to the old. Where the new subglacial outlets proved insufficient to 
carry off the waters, they would rise through crevasses and escape over 
the surface. The situation of many of the larger plains of reticulated 
kames is rather favorable to the formation of crevasses, and a large part of 
these overflow channels were probably subglacial. But when the summer 
floods came and found the old channels clogged the emergency was press- 


ORIGIN OF LARGER COMPLEXES. 465 


ing. The floods must find instant escape in some way, and the natural 
result would be a complicated system of surface channels. These supposed 
surface channels probably served for the escape of the waters only for a 
short time each year—during the time of highest floods—yet they would 
contain some sediment. Thus probably streams both above and beneath 
the ice contributed to the formation of such ridges as were formed in chan- 
nels between walls of ice. 

While it is true that the situation of the large complexes of western 
Maine is in general favorable to a free flow of ice and the production of 
crevasses, yet the reticulated ridges often do not expand to fill a whole val- 
ley, as they would if the ice were so shattered that the subglacial waters 
could freely pass along crevasses in any direction. They cross valleys 
and go over cols in a way impossible unless the ice at the sides of the 
system formed solid barriers. 

These considerations bear on the question whether the overflow chan- 
nels were all subglacial Admitting that the huge central ridges were 
deposited in subglacial tunnels, the question recurs whether so many addi- 
tional channels could be formed subglacially. The answer depends on the 
number and arrangement of the crevasses. If the ice was solid at the sides 
of a clogged subglacial channel, I see no physical process whereby the 
stream could form new subglacial outlets. The facts showing considerable 
solidity of the ice at the sides of the glacial rivers are many. These facts 
favor the hypothesis that a portion of the overflow channels were super- 
ficial. Probably the water would rise through crevasses onto the surface 
only after the ice had become rather thin. It has been noted before that 
the transverse ridges are sometimes composed of finer matter than the main 
longitudinal ridges. This is consistent with the hypothesis that the former 
were deposited in superficial channels, but the question can only be settled 
by examining their stratification. 

During the time of formation of the kames the ice must in many 
places have been in motion. Many of the plains have no transverse hills 
in front of them and the ice motion could continue up to the last. If at 
this time the ice had power to push forward subglacial sediments, the trans- 
verse ridges which had to bear from their sides the force of the sea, ought 


to be of great breadth and of gentle slopes, like the lenticular ridge of till. 
MON XXXIV——30 


466 GLACIAL GRAVELS OF MAINE. 


The point did not occur to me while in the field and was not specially 
studied, but I have no note of transverse ridges having a different con- 
tour from the longitudinal ridge adjacent. 

Moreover, we must assume that the ice front was retreating. When in 
the retreat the ice had receded to a given point, the streams at that point 
were ready to cease to be, as hitherto, glacial, and were about to become 
frontal. The matter poured out from the front of the ice would overlie 
the previously deposited sediments. In the case of a narrow subglacial 
channel changing to a broad osar channel, the retreat of the ice would im 
part be equivalent to the gradual and recessive melting of the roof of the 
vault, and then the subsequent lateral enlargement of the canyon thus 
formed. In this case there are two retreats to be considered—one of the 
ice over the channel and the other of the ice at the sides of the channel. 
When, as is true in many cases, there is a ridge of coarse matter in the 
midst of the osar-plain, we may consider it deposited in a subglacial chan- 
nel. There are many ways in which such a channel could change to a 
broad channel open to the air. Perhaps as plausible a theory as any is that 
often the roof melted recessively northward at the same rates. If so, the 
matter of the broad plain would be, with respect to the receding subglacial 
stream, frontal matter, and this would account well for its rather horizontal 
stratification and level surface. But though frontal with respect to the roof 
of the subglacial stream, it was contained between walls of ice in whole or 
in part, and hence was glacial with respect to the regions over which the ice 
had all melted. 

Now, as in the retreat of the ice as a whole the glacial streams had 
continued to pour out their sediments from the ice front over the previously 
deposited reticulated gravels, they would at once begin to fill up the kettle- 
holes and change the ridged to a level plain. The fact that the ridges over 
large areas still preserve their individuality proves that but little frontal mat- 
ter was deposited upon them. This in many cases can readily be accounted 
for, and when a good relief map is obtained perhaps all the cases can be 
explained. In the region of southwestern Maine under discussion the north- 
and-south series of gravels are connected by a number of east-and-west 
series. The latter probably date from the last part of the kame period, 
when the glacial water could escape eastward by subglacial or englacial 
channels or over the ice of the valleys more easily than over the hills to the 


ORIGIN OF LARGER COMPLEXES. 467 


south. Thus the main supply of water from the north would be cut off 
before the ice at the sides of the reticulated ridges melted, and in this 
region of short hills the supply of frontal or oyerwash matter was small 
and due to local action. But in the valley of the Saco River from Hiram 
to Steep Falls the sedimentary plain that borders the river presents in cer- 
tain places just such a structure as would result if reticulated ridges were 
subsequently overlain by much frontal matter, at the same time being more 
or less washed away and reclassified. The valley is inclosed by such high 
hills from Steep Falls northwestward that there was no late diversion of 
glacial waters out of the valley, while numerous glacial rivers have left 
gravels showing that they flowed into it. ‘These are true ice-channel gravels, 
not overwash, and the plain of the Saco is therefore an intermediate forma- 
tion between the frontal or overwash apron and the reticulated ridges, and 
contains both of those formations. 

One method of the formation of reticulated ridges has been observed 
by Professor Wright at the Muir glacier and by Professor Russell at the 
Malespina glacier—one form of the overflow gravels suggested above. A 
frontal or overwash sheet of gravel is first deposited over the thin marginal 
ice. During the subsequent melting, channels are cut in the ice beneath 
the gravel by streams, apparently of local origin, and the overlying gravel 
tumbles from both sides into the channel, where it is more or less water- 
washed and stratified. It is highly probable that ridges having a pellmell 
internal structure often originated in substantially this manner, and it is one 
of the means employed to produce the mounds and hollows of the moraines. 
The clogging of the mouths of subglacial tunnels would bring the streams 
to the surface of the terminal slope, like those of the Malaspina glacier, 
when they would deposit on the marginal ice a more or less ridged sheet 
of gravel, which would become a jumble of ridges, mounds, and hollows 
during the unequal melting of the subjacent ice. But while admitting this 
as one of the methods of the formation of reticulated ridges and kettle- 
holes not forming a part of the delta plexus, I regard it as subordinate in 
rank to sedimentation im connecting ice channels by the great osar rivers 
themselves, for most of these ridges are stratified and must have been 
formed basally, not on the ice. Where large ridges are composed of coarse 
material and are stratified, we can evoke only the largest and most rapid of 
glacial rivers, not local brooks undermining sheets of clay. 


468 GLACIAL GRAVELS OF MAINE. 


OSAR BORDER CLAY. 


This interesting deposit is so fully discussed im connection with the 
Anson-Madison system’ that little need here be added. The general 
conception which I have formed of it is as follows: 

First an osar was deposited in a narrow channel, just as the other 
ridges were. This channel was subsequently broadened by lateral melting 
and erosion of the ice so as to become one-eighth to one-fourth of a mile 
wide, and in some cases wider. If a large glacial river flowed in this broad 
channel, an osar terrace was formed within it. If the supply of water was 
small, its motion in so broad a channel was necessarily slow, and even the 
fine clay could be precipitated This clay is as truly a glacial sediment as 
the sand and gravel, yet the titles ‘‘“eskers” and “‘osars” have come to be 
applied to ridges of coarser matter, and hence I give a special name to the 
plain of clay that borders the central ridge. Structurally I can not dis- 
tinguish it from the plain of sand and gravel that borders the central ridge 
of the broad osar. The character of the sediments depended simply on the 
velocity of the stream that flowed in the broad channel. he evidence is 
conclusive that this border clay was contained in a channel inclosed wholly 
or in part by ice. This evidence is stated elsewhere and need not here be 
repeated. The border clay is found only in level regions below the eleva- 
tion of about 400 feet, and the slow velocity of the water may in several or 
most cases have been due to the sea backing into the channels. 

In several places below the highest sea level what appears to be border 
clay contains marine fossils. his is the case unless reaches of clay depos- 
ited in the open sea alternate with border clay in the course of the same 
system. But the border clay has in these cases been covered by more or 
less clay deposited in the open ocean after the melting of the ice at the sides 
of the broad ice channel. It will require a more detailed field examination 
than I have been able to give these deposits in order to determine what 
proportion of the clay was deposited in the open sea after the melting of 
the ice of the whole region, and what was left in the bottom of broad chan- 
nels and formed long fiords by which the sea penetrated for considerable 
distances, perhaps several or many miles, into the thin ice-sheet of late gla- 
cial time. It was in such broad channels that the narrow marine deltas were 


‘See p. 180; also Clinton system, East Vassalboro branch, p. 170. 


DELTAS IN FRONTAL GLACIAL LAKES. 469 


formed. JI have no proof of any such fiords extending into the ice that 
did not proceed from the broadening of the channel of a glacial river. Nor 
is it here assumed that they were at all times filled with salt water. They 
were perhaps more nearly estuarine, with brackish. water. 

The border clay is here and there strewn with nonpolished bowlders 
which have typical till shapes. They must either have been transported 
by floating ice or have dropped from glacier ice. In this case, as well as 
in that of similar bowlders in the marine clays, I prefer the interpretation 
of floating ice. I can not perceive any way of regarding these as proof of 
an advance of glacier ice after the deposition of the clays. They do not 
constitute a sprinkling of till, much less such a sheet as would be left if 
the ice readvanced over the clays, or if the border clay were formed sub- 
glacially. I see no admissible interpretation but that the osar terraces and 
the border clay were both laid down in channels open to the air. The 
angular bowlders overlying the border clays are found up to 400 feet. In 
part they must be due to floating ice of the sea, but there must have been 
ice floes or little bergs floating in these broad glacial channels, which, as 
they melted, dropped their burden upon the clay. Some of these bowlders 
are 8 or 10 feet in diameter. 

The narrow marine deltas, the broad osars, the border clay, the broad 
solid or plain-like massives, all unite with the lake deltas and the kames, 
eskers, and osars themselves to prove the gradual enlargement of the chan- 
nels and pools within the ice. Both subglacial and superficial streams 
could not only hold their own against the inflow of the ice tending to close 
the channels but could enlarge them. 

DELTAS DEPOSITED BY GLACIAL STREAMS IN FRONTAL GLACIAL 
LAKES. 

The best examples are situated in Dixmont and Unity and are described 
elsewhere.’ All are small, only 5 or possibly in one case 10 miles long. 
Regarding the frontal lakes, it is here only necessary to remark: (1) They 
mark stages in the retreat of the ice northward. (2) They collected between 
the ice front on the north and hills situated to the south. Thus on a small 
scale they were equivalent to the lakes that fringed the southern border of 
the ice-sheet in central New York and Ohio. (3) They differ in no essential 


1See pp. 141, 146. 


470 GLACIAL GRAVELS OF MAINE. ° 


respect from the dead water that occupied the glacial channels north of the 
hills, except that they were not confined within so narrow limits. (4) Thus 
far I have not been able to find fossils in their sediments. Maine is so far 
from the terminal moraines of southern New England that it will not be 
surprising if it shall be found that the ice front retreated northward faster 
than the land plants and terrestrial invertebrates could advance. More- 
over, these organisms had just been wholly driven out of New England, 
unless possibly on a few of the higher mountains and islands. West from 
Staten Island the plants could follow the retreating ice by the shortest lines, 
i. e., at right angles to the ice front. In New York and Pennsylvania it 
would be much easier for them to accompany the ice in its retreat than 
for them to travel obliquely after the ice northward and eastward all the 
way from New Jersey to Maine. Prof. B. K. Emerson has recently found 
fossils in sediments of late glacial or early postglacial age situated in 
central Massachusetts. It would require only a third as long for terrestrial 
plants and animals to travel to that place as to Maine, and probably the 
ice was all melted before they reached the latter place. If there was any 
retreat for these plants and animals from the ice in eastern British America 
it has not been reported. Reference is here of course not made to algze 
naturally inhabiting snow and ice. 


VALLEY DRIFT. 


VALLEY DRIFT OF PURELY FLUVIATILE ORIGIN. 


In a country of hills and rather level valleys, like most of Maine, the 
surface waters erode the uplands, carry their load down the steeper slopes 
of the hills, and then may or may not drop the coarser portion as they 
reach the more moderate slopes of the valleys. In Maine the hills are 
usually diversified by numerous small lateral valleys, sometimes due to 
inequalities in the distribution of the till, but more often to the accidents of 
preglacial weathering and erosion. Most of the surface waters of the 
uplands are thus soon converged into valleys and ravines. Erosion by 
surface waters must always have been most active in these smaller valleys. 

If the deep sheets of alluvium which cover the bottoms of the broader 
valleys are composed of material eroded from the uplands by surface 
waters after the melting of the ice, we ought now to find a system of 
rayines comparable in volume to the valley drift. The brooks that form 


VALLEY DRIFT OF FLUVIATILE ORIGIN. 471 


on the hillsides have eroded channels in the till, sometimes 10 to 20 
or even 30 feet deep, but in general they are small and their united 
volumes insignificant compared to the great sheets of valley drift. The 
surface of the land is such that there never could be a great diffused or 
general ablation, but the erosion must have been chiefly confined to the 
hillside ravines. . 

While, then, there must have been considerable erosion of the upland 
till since the disappearance of the ice, especially immediately after the 
melting, while the till was still unprotected by vegetation and the upper 
till somewhat unconsolidated, yet this furnished only a small part of the 
valley drift. 

The impossibility of thus accounting for the valley drift is still further 
emphasized by the relatively short time in which this supposed erosion of 
the uplands must have been accomplished. The upper stratum of the 
valley drift often extends beneath the sea level of that time as deltas 
deposited by the rivers in the sea. No matter what origin we assign to 
the valley drift, the great mass of the deposit must have been laid down 
between the time of the melting of the ice at the place of deposit and the 
retreat of the sea to its present level. The limited erosion by the sea dur- 
ing this time proves it to be geologically a very brief period. 

Furthermore, we must remember that the till resists erosion far better 
than the sedimentary drift. For a large part of postglacial time the 
streams have been able to erode and transport the sediments of the valleys 
more rapidly than the upland erosion. This is proved by the great size of 
the valleys of erosion which the streams have excavated alike m the marine 
clays, in the valley drift, and in the glacial sediments proper. Only here 
and there locally has deposition exceeded transportation in the lowland 
valleys. Any such relation of the comparative difficulty of erosion of the 
till and the sediments, or of land slopes to rainfall, as now exists, could 
plainly never have caused the great accumulation of alluvium in the 
valleys. When once the tenacious till was eroded, the streams would have 
been able to transport most of the loosened matter direct to the sea. Only 
the coarser matter would be left in the valleys, and a fine clay, like the 
lowest layer of the valley drift, would be impossible under the conditions 
assumed. ° 

Moreover, we must account for the coarse residual matter that would 


472 GLACIAL GRAVELS OF MAINE. 


be left on the uplands, if there had been so great an erosion of the till after 
it had become bare of ice that it furnished the material for such thick sheets 
of finer sediment. The till contains material of all sizes from bowlders 
down to rock flour. Any large erosion of the surface till, especially where 
it would largely be localized in the smaller upland ravines and valleys, 
ought to have left a mass of residual matter composed of the bowlders and 
larger stones. This ought now to be either in the ravines of the hills where 
it would be left when the finer matter was carried away, or to form alluvial 
cones in the larger valleys near the mouths of the steepér hillside brooks. 
In the mountains such cones are noticeable, but they at once show them- 
selves to be composed of different material from most of the valley drift, 
and they add very much to the difficulties of the hypothesis that the valley 
drift is derived from fluviatile erosion products. Conclusion: Unless locally 
in the mountains, there is no such body of residual coarse matter left on the 
hillsides, or as alluvial cones at the mouths of brooks, as testifies to any 
great erosion of the till since it was deposited by the ice, still less such a 
vast quantity as would be required by the fluviatile hypothesis. Indeed, 
the small sizes of the brook channels of the uplands is surprising. I 
have known near the base of Pikes Peak a channel one-fourth of a mile 
long eroded in a single storm to a larger size than many a large perennial 
brook in Maine has been able to erode in all the time since the melting of 
the ice. 

One class of fluviatile residual gravels here deserves further notice. 
The larger streams and rivers have not infrequently excavated canyons in 
the till or rock since the melting of the ice. This most often occurs in east- 
and-west valleys, where the ice often left deep morainal sheets or ridges 
across the valleys. Here rapids and waterfalls were formed. The rivers 
excavated a channel in the till barrier and carried the coarser matter down a 
short distance below the foot of the swift water, where it was left as terraces 
of valley drift. The stones are usually subangular, and are easily traceable 
in the midst of the original valley drift. Such a deposit at Kingman is 
elsewhere described (see p. 98). - Now if large rivers have left the residual 
matter from channels formed in the till, much more ought the brooks to 
show such proofs of any large erosion of the till. 

Another consideration is this: Most of the east-and-west valleys contain 
less valley drift than north-and-south valleys, and it is on the average of 


VALLEY DRIFT OF FLUVIATILE ORIGIN. 473 


finer composition. No reasons for greater fluviatile erosion in one class of 
valleys than in the other, other things being equal, have as yet suggested 
themselves. 

The quantity of the valley drift in valleys is very greatly dependent 
on the positions of the glacial rivers, and is to some extent independent of 
the drainage surface. 

While, then, we must assume a certain amount at rain wash and erosion 
of till by streams as having helped to bring down sediment that is now in the 
valleys, this process can account for only a small part of the valley drift. 

Was the valley drift deposited in the sea? If so, it might be under 
the following conditions: 

1. The valley drift was deposited, in part, by glacial streams pouring 
into the sea. It is plainly a different formation from the marine glacial 
delta as ordinarily developed. It is possible that in narrow valleys the 
structure would be modified by tidal wash and scour, yet I see no way to 
account for the total absence of the reticulated ridges formed at the land- 
ward ends of the deltas. 

2. We may attribute the alluvium to erosion by the sea waves. If so, 
the residual beach gravels left after so much of the finer matter was washed 
away ought to be recognized, and such are not found. Even in the most 
exposed coasts the till was not all washed away. Still less can we postulate 
in the interior valleys, which the rise of the sea would change into land- 
locked fiords, any such erosion as the valley drift calls for. 

3. Sheets of valley drift comparable in most. or all respects to the 
valley drift of the higher parts of Maine are found in the vicinity of the 
Green and the White mountains, and thence extend south through northern 
New England far above any admissible or alleged former level of the sea. 
Even if we admit that a part of the valley drift is marine, it is certain that 
the larger part was deposited above the sea. 

4. The valley drift was deposited in the sea by ordinary rivers. This, 
I think, is true for a portion of the valleys, but only below the former level 
of the sea, say 450 or possibly 500 feet in the interior valleys. This 
structure will be referred to hereafter, and the limits wherein found. 

I conclude, as the result of this discussion, that the valley drift extends 
above the former level of the sea. It is a subaerial formation, as a whole, 
though it locally passes into fluviatile deltas deposited by the ordinary 
rivers in the sea. 


474 GLACIAL: GRAVELS OF MAINE. 


VALLEY DRIFT OF SEMIGLACIAL ORIGIN. 


The evidence that the valley drift was derived from the drainage of 
the ice-sheet is as follows: 

1. The valley drift can not be due to the erosion of till after it has 
become bare of the ice, either by meteoric and fluviatile waters or by the 
sea. We have no other assignable origin than glacial. 

2. The shapes of the stones of the valley drift are im general those of 
the glacial gravels after they have been rolled several miles by the glacial 
streams. The stones are in most cases much more worn and rounded than 
those contained in the channels excavated in the till by existing streams, 
except on the steeper slopes of the mountains. The stones of the gravel of 
the valley drift are often as much worn as stream gravels known to date 
from Tertiary time, but this they can not be, since the stream gravels of 
preglacial age were removed by the ice or incorporated with the till. We 
have no machinery for the production of such great masses of rounded 
gravel, acting within valley-drift time, except glacial streams. 

3. We find in the valley drift here and there masses of coarse matter 
bearing no relation to the local land slopes. Now coarse matter collects 
near the ice where the subglacial streams emerge from the ice. The 
lingering of the ice front at a given place would cause local accumulation of 
coarse matter near that point. The occurrence within the valley drift of such 
a mode of assortment of sediments as does not depend on the slopes of 
the land requires us to postulate glacial conditions. An instance like this 
is found near North New Portland. (See p. 188.) 

4. The last-named argument would be strengthened if at the same 
time with the local coarseness of material it was found that the body of 
coarse matter formed a low bar or ridge across the valley and rose above 
the level of the valley drift both to the north and to the south of it. This 
is the condition at North and East New Portland. In various places lakes 
within the valley drift have probably been formed in this manner. 

5. The glacial origin of the valley drift would be confirmed if near 
the supposed overwash plain of sediment terminal moraines were found. 
Such occur at East New Portland, in the valley of the Androscoggin River, 
at the State line, and near the Katahdin Iron Works. 

6. In several cases an osar broadens southward and passes by degrees 


RELATIONS OF VALLEY DRIFT AND OTHER DEPOSITS. 475 


into a sheet of gravel extending across the valley from side to side and not 
distinguishable from other valley drift. To the south this does not take the 
form of an osar terrace (broad osar), but is true frontal matter, passing by 
degrees into fmer sediments and finally into marine clays. Here the glacial 
origin of the valley drift is unmistakable. 

7. That the valley drift is usually more abundant in north-and-south 
than in east-and-west valleys appears to be due wholly to the fact that this 
was the prevailing direction of the glacial streams. In other words, the 
law appears to be that where the elacial streams were most active there we 
find the most valley drift. This gives a distinctly glacial facies to the valley 
drift. The sizes of the drainage basins, especially of the smaller valleys, 
often bear no relations to the quantity of the drift. This points distinctly 
away from the fluviatile hypothesis and toward the glacial. 

Summary— These facts abundantly prove that overwash plains of glacial 
sediments formed in front of the ice, and that they are typical valley drift. 
If the glacial hypothesis thus accounts for that portion of the valley drift 
directly associated with moraines, osars, and other unmistakable glacial 
phenomena, we need no other hypothesis to account for those sediments 
that were deposited at longer distances from the ice front of that time, since 
the latter are what should be expected on that hypothesis. 


RELATIONS OF THE VALLEY DRIFT TO THE OTHER GLACIAL AND THE 
MARINE SEDIMENTS. 


Comparing the valley drift to the other glacial sediments, we find the 
following relations: 

origin —They all were at one time transported by glacial streams. 

Places of deposition—T])eposits within ice channels include all the eskers, 
kames, osars, and border clay of the varieties elsewhere described. 

Deposits poured out in front of the ice by the glacial streams include 
the following: The marine deltas with most of the marine clays and sands, 
deposits in frmging or marginal lakes, and overwash aprons or valley drift 
poured out on land sloping away from the ice front. 

I pause in passing, however, to note that erosion of the till by the 
sea waves contributed to the marine sands and clays; so, also, water wash 
from the till contributed to the valley drift. But in both cases the glacial 
sediments so greatly exceed in quantity the eroded till that practically we 
may speak of both deposits as of glacial origin. 


476 GLACIAL GRAVELS OF MAINE. 


HISTORICAL RELATIONS. 


In a preceding chapter the manner of the retreat of the ice has been dis- 
cussed and the lines of the front have been marked on the map (Pl. XX XT) 
as they are supposed to have been at various periods. The lines of retreat 
seem to indicate not only that the melting took place from above down- 
ward but that it was most rapid at the margin. They furnish no proof that 
any large bodies of stagnant ice were isolated from the main body by the 
melting of the ice to the north of it, unless the ice situated south of east- 
and-west glacial rivers be so considered. Thus, near Oxford there is proof 
that, at a time when a broad plain of sand was being deposited, it was kept 
from spreading into Thompson Pond by the presence of ice in the basin of 
that lake. The valley of the Little Androscoggin River may at this time have 
formed an arm of the sea from Oxtord or Norway to Auburn. (See p. 225.) 
In the Androscoggin Valley in Gilead and Shelburne, New Hampshire, also 
in the Kennebec Valley from Embden northward, and elsewhere, the valley 
drift often does not spread into lateral valleys. This suggests that these 
laterals were filled by ice at the time the central plains were being deposited. 
While thus there are indications that glacial channels often broadened till 
they covered all the valleys in which they were situated, and thus the purely 
glacial sediments deposited in channels back from the ice front passed by 
degrees into frontal bodies of overwash, the probability is that the retreat 
of the ice as a whole took place from the margin and the glacial stream 
channels were bordered by ice until the retreat of the general frontal line 
back to that place. 

1. In valleys containing osars the larger glacial rivers were already 
established, draining areas 5 to 10 or more miles in width. The same pro- 
cesses that collected the glacial gravels with so few visible ravines of erosion 
in the ground moraine or till sufficed to accumulate the material of the val- 
ley drift in the channels of the glacial streams. In all cases the smaller 
tributary subglacial streams seldom left gravels, except for short distances 
near the main osars. This indicates that their channels were small as com- 
pared to the flow of water. Most of their work, including tracts of erosion 
of the ground moraine, glacial potholes, ete., has been covered out of sight 
by the englacial till. In a word, we have in the glacial streams a machinery 
for diffused erosion without the ravines required by the hypothesis of till 
erosion by rains and streams after the melting of the ice. 


—— 


RELATIONS OF VALLEY DRiFT AND OTHER DEPOSITS. ATT 


The phenomena of delta or diverging branches of glacial rivers prove 
that from time to time these streams found their channels clogged or were 
for some other reason diverted to new channels. Admitting that these acci- 
dents were liable to happen at any time, still I can see no especial liability 
of their happening during the very last of the ice at a particular place 
except on account of the rising of a hill in front. Transverse hills crossed 
by glacial rivers might often force the streams to escape either east or west 
after the ice-sank to the tops of the hills. In continuous north-and-south 
valleys containing gravels deposited in ice channels the retreat would cause 
sediments to be carried beyond the ice front, where they would overlie or 
be mixed with the previously deposited ice-channel gravels. Cases of this 
sort of deposition are found in the valley of the Saco River for many miles 
above Steep Falls, in the upper Kennebec Valley, and elsewhere. 

Where the very latest conditions favored the formation of the broad 
osar, the channel might often continue to widen till it extended across a 
whole valley. The marginal part of the plain of sediments that would 
extend across the valley might be valley drift, and we should hardly be 
able to distinguish it from the osar terrace proper. But where we find the 
narrow osars or reticulated ridges we could not fail to distinguish them from 
a later deposit of overwash matter, which would necessarily border or 
overlie them. In general, it is astonishing to note how suddenly sedimen- 
tation ceases. Kettleholes and ridges of coarse matter are found with their 
shapes clearly defined. Often there has been but little postglacial erosion 
to fill up the bottoms of the kettleholes. We must, therefore, account not 
only for the valley drift, but also for its absence from long reaches of the 
osars and reticulated kames right on the lines of glacial rivers, where, on 
the glacial hypothesis of the valley drift, its presence would be expected. 

In many cases the relief forms of the land would naturally cause the 
flow of a glacial river to cease at a given place before the ice front had 
retreated to that point. Thus, where the ice flowed over transverse hills 
there would be local deflections of ice movement during the last days of 
the ice. This would make it mereasingly easy for the subglacial streams 
to find new channels east or west along the valley north of the transverse 
hills, at the same time that the lowering of the level of the ice would make 
it increasingly difficult to maintain the flow south over the tops of the hills. 
Often we can trace the new channels by transverse series of gravels. Thus, 


478 GLACIAL GRAVELS OF MAINE. 


in the hills of Oxford and northern York counties three great north-and- 
south osar series are connected every few miles by transverse lines of 
gravels, several of which follow the east-and-west valleys. But in general 
we must suppose that the latest channels of deflection were in use for too 
short a time to become enlarged sufficiently to permit within them the 
deposition of gravels. 

For various reasons, then, the waters of the longer osar rivers often 

did not form frontal or overwash gravels in front of the ice during the 
retreat. If they had continued to flow up to the last, the gravels previously 
deposited within channels in the ice ought to have been covered or flanked 
by matter poured out in front of the ice during the retreat. That this did 
not happen is best explained by supposing the streams to have been diverted 
to new channels at some time not long previous to the final melting of the 
ice at those places. Below the level of the sea it would facilitate imter- 
"pretation if we could assume that some of the rivers ceased to flow in 
consequence of the pressure of the rising sea, also if we could assume that 
toward the last the melting of the ice im the far interior valleys of the State 
was more rapid below sea level than above it. This would be equivalent 
to the formation of bays of the sea penetrating into the ice beyond the 
general frontal line, a condition that would facilitate interpretation at 
Oxford and elsewhere. Such an outline would not be inconsistent with 
the lines of frontal retreat as set forth elsewhere, but thus far I do not 
find direct proof of it, unless through the evidence furnished im some cases 
by the osar border clay. 

2. The absence of osars in north-and-south valleys proves that the 
channels of the glacial streams had not become sufficiently enlarged to per- 
mit deposition within them. The streams must have transported all their 
sediments to the ice front and poured them out as frontal overwash or valley 
drift. Where these streams were united into one main river we would find 
the coarsest matter arranged along the course of the stream, and the sedi- 
ments would grow finer on each side. The coarser mass would not have a 
definite border or arched cross section. Where there were several glacial 
streams there would be a corresponding number of coarser belts. Under 
some conditions these might form reticulations and inclose lake basins and 
kettleholes, like those in the valley of the Androscoggin River in Shelburne, 
New Hampshire. These would often be filled later by other drift, but 


eS ee ee 


ee 


RELATIONS OF VALLEY DRIFT AND OTHER DEPOSITS. 479 


might survive in very broad valleys. In some cases these reticulated ridges 
may have been deposited in ice channels near the front. 

Obviously the slopes of the land, the breadth of the valleys, the size of 
the streams, etc., would determine the development of the gravels after 
passing out of the ice. 

3. In numerous eases there are north-and-south valleys or passes lead- 
ing southward to low cols of transverse hills. In late glacial time they 
contained lobes of ice which were practically local glaciers. Here we not 
seldom find, a short distance north of the top of the col, a short esker and 
small terminal moraines. Ina number of such valleys there is considerable 
sediment along the northern slope for several miles. The most probable 
interpretation is that a fringing lake formed between the ice and the hill in 
front, and that the glacial streams continued to pour into this during several 
miles of ice retreat. 

4. Some valleys contain terminal moraines of considerable size. This 
implies that the ice front remained stationary, or nearly so, for a time. 
Such moraines are found in the valley of the Androscoggin near the 
line between Maine and New Hampshire, near Kast New Portland, and 
elsewhere. 

In such a case we ought to find a very deep overwash apron near 
where the ice stood or paused, and it might even form a dam across the 
valley and inclose a lake. From this point the sediments would become 
finer in composition down the valley, and might even pass into the marine 
clays. 

5. Some east-and-west valleys do not contain osar gravels. Near the 
end of glacial time the waters of these valleys could not escape southward 
over the hills bounding the valleys on the south, and the ice would be 
rather stagnant. ‘There is here no direct proof showing the courses by 
which the local waters escaped. Some of them would flow in subglacial 
channels, some might escape between the ice and the hill to the south, or 
superficially or englacially. It has already been remarked that such of the 
east-and-west valleys as contain no osar gravels, or were simply crossed 
by them, contain valley drift which is but little waterworn. This points to 
small local streams, mostly subglacial and transverse to the ice flow. Such 
directions would often cause the streams to transport sediments into arms 
of the sea or into distant north-and-south valleys. After the ice front had 


480 GLACIAL GRAVELS OF MAINE. 


retreated northward to the bottom of an east-and-west valley, all the sedi- 
ments derived from the drainage of the ice on the north side of the valley 
would be swept into the stream, which then would flow in the bottom of the 
valley substantially parallel with the ice front of that time. As the ice 
retreated northward up the hill more or less sediment would be poured out 
on the open hillside below the ice, whence much of it would be carried 
down the hill to the bottom of the valley. 

6. In some east-and-west valleys hillside eskers are found. These 
were deposited by glacial streams that flowed down the southern slopes of 
rather high hills and left their coarser sediments on the sides or near the 
bases of the hills. Sometimes here they are lost and the streams must 
have escaped superglacially or in channels too narrow to permit sedimen- 
tation. In other cases this class of gravels expand into deltas and finally 
merge into the alluvium of their valleys. Evidently this valley drift dif- 
fers in no essential from that not associated with the osar gravel, except that 
we can trace its glacial origin more directly. 


RELATION OF THE VALLEY DRIFT TO THE MARINE BEDS. 


We now approach a series of phenomena very difficult to interpret. 
In a paper read at the Boston meeting of the American Association for the | 
Advancement of Science, in 1880, I estimated the elevation of the sea in 
the interior of Maine at 300 to 350 feet. The highest fossils I had been 
able to find in the interior valleys were at 215 to 230 feet in Palmyra. I 
had also discovered certain high deltas, as that at Curtis, Leeds, that were 
from 300 to 350 feet in elevation. My estimate was based on the deltas, 
assuming that the higher marine beds were nonfossiliferous. Later, when I 
discovered (1885-86) that the elevation of the beaches along the outer 
coast-line did not exceed 200 to 230 feet, I became quite doubtful where to 
place the limit in the interior. It even seemed possible to interpret the: 
highest deltas as formed in lake-like bodies that toward the south opened on 
land bare of ice, while the basal clay of the valleys would on this hypothesis 
be a form of valley drift analogous to the loess. 

The observations of Baron De Geer, made in 1891, cover most of the 
area of the elevated marine beds. They make it evident, in a way that 
local observations could not do, that the apparent rise of the sea in late 
elacial time was due to a general subsidence of the glaciated area. From 


FORMER HEIGHT OF SEA. 481 


observations in Maine alone I have not felt justified in maintaining the subsi- 
dence on our coast and that in the St. Lawrence Valley as contemporaneous. 

Accepting the general conclusions of De Geer, I assume that the post- 
elacial elevation of the land in the interior of Maine has been about three 
times that of the coast. 


FORMER HEIGHT OF THE SEA. 


To determine the highest elevation of the sea in the valleys of the 
interior of the State, we have to depend on the following means: 

1. The elevation of fossils. Possibly the time may come when this 
method will be applicable, especially by means of microscopical examina- 
tions. Thus far I have found no macroscopical fossils in large areas of the 
marine clays, and do not find the absence of fossils in the glacial! marine 
sediments fatal to their being deposited in the sea. 

2. The elevation of raised beaches. On those portions of the coast 
region where the hills were exposed directly to the surf, with few or no 
protecting islands lying to seaward, we readily find such beaches. Even 
near the coast the presence of hills toward the south that would form 
islands has often so diminished the force of the waves that the beaches are 

inconspicuous and are traceable with difficulty. At the time the sea stood 
at its highest elevation the interior valleys contained landlocked bays or 
fiords of the sea. In the Sebasticook and Penobscot and others of the 
broader valleys it is possible that the waves had sufficient force to leave 
traceable beaches, though I have not traced them. But these places are 
not where the valley drift meets the marine beds. These two formations 
meet in the valleys where the crooked fiords were usually less than 5 miles 
in breadth and where we can not expect to find distinct beaches. 

3. The projection of lines of equal elevation. By projecting the eleva- 
tions of the highest raised beaches on the exposed coasts, selecting points 
at different distances from the outer coast line, we find the rate of differ- 
ential subsidence. Assuming this rate to have been the same over the 
interior as near the coast, we can then calculate the positions of the lines 
of equal elevation. Following this method, Baron De Geer calculates that 
the isobases, or lines of equal elevation, would take the following courses: 

* * * An isobase drawn through points which have been upheaved 300 feet 


passes probably from near Niagara Falls, by Albany, New York, and Augusta, Maine, 
MON XXXTV——31 


482 GLACIAL GRAVELS OF MAINE. 


to Moncton, New Brunswick, whence it turns backward, running northwesterly and 
northerly, crossing the St. Lawrence estuary about halfway between Cape Gaspe 
and the Saguenay. 

The 600-foot isobase is probably to be drawn from Georgian Bay past the outlet 
of Lake Ontario, through the southern part of the Adirondacks, and thence east- 
northeast nearly to Moosehead Lake. Here it makes an abrupt bend to the north 
and west, similar with the loop of the 300-foot isobase at Moncton, and runs first 
westward to some point not far from Three Rivers, and thence, funine again ingln 
eastward, it passes along the north shore of the St. Lawrence estuary.' 

Manifestly this method is not complete until the elevations of all the 
traceable beaches are accurately determined, and thereby the amount of 
local warping, if any. 

The position of the shore line in any of the mland valleys would, 
according to this method, lie where the profile of the valley, drawn in a 
plane perpendicular to the lines of equal elevation, intersects the hori- 
zontal line marking the old 
sea level. Thus in the dia- 


woomues.q Old SeaLevel. SOMILES. £ x 
i 
Fig. 36.—Diagram illustrating the method of finding the highest sealevelin oram the line acb repre- 
an interior valley. 
sents the profile of a valley 
supposed to be normal to the limes of equal elevation. At b and ¢ are 
raised beaches, and the profile is at these pomts depressed below the hori- 
zontal line distances proportional to the heights of the beaches at those points. 
This determines the position of the point a, which marks the former shore. 
4. The elevation of marine deltas. The deltas of the interior at 300 
to 350 feet are now interpreted by me as marine, but possibly this point 
may be disputed. They certainly do not bear such relations to the fossil- 
iferous clays as the deltas nearer the coast. But sheets of clay and sand 
are found extending from the deltas up to considerably higher elev: ations, and 
therefore under no conditions do the deltas mark the highest level of the 
sea. Indeed, it should be expected that deltas would be formed in front of 
the ice, often at a considerable depth beneath sea level. The higher deltas 
are more than 100 feet above the highest fossil thus far found. Marine fos- 
sils are found in Lewiston, Winthrop, Norridgewock, Skowhegan, Palmyra, 
Unity, and other interior towns. The highest deltas are found only a few 
miles beyond the fossils. Both together constitute valuable collateral evi- 
dence of the presence of the sea in the interior valleys, but do not give 
the extreme limit. 


‘Am. Geol., vol. 9, p. 248, April, 1892. 


ee eee 


FORMER HIGHT OF SEA. 483 


5. The deeper interior valleys now occupied by streams and rivers. 
The main valleys are often connected by cross or transverse valleys or low 
passes. Up to the highest level of the sea we should expect these trans- 
verse valleys to have been occupied by straits forming a complex system of 
reticulating channels surrounding numerous islands. A corresponding series 
of sands and clays would mark these old channels or straits. Up to the 
height of these transverse plains of fine sediments it is at least possible that 
the sea extended. Yet it is also possible that the floods of rivers might 
rise above the divides between neighboring valleys, and thus an overflow 
might take place from one to the other. It thus becomes necessary to dis- 
tinguish a possible form of valley drift from marine beds before it becomes 
certain whether the transverse plains of fine sediments mark the presence of 
the sea. 

6. The character and structure of the sediments. This constitutes 
another method of distinguishing between the valley drift and the marine 
beds. Into the main marine bays of the time when the sea stood at its 
highest level poured large rivers which to the north were fed by waters of 
the melting ice-sheet. Above sea level they were depositing valley drift; 
within the sea, fluviatile marine deltas. Estuarine deposits would form the 
transition between the two. The determination of the points of transition 
would be rendered difficult by the rise and fall of the tides, and especially 
by any general rise or fall of the sea level whereby at successive periods 
the fresh and salt waters met at different places. If we should find a great 
change in the coarseness of the sediments taking place within narrow 
vertical limits, proving considerable slowing of the waters at that point, 
and especially if this were observed in several valleys at the same relative 
position to the lines of highest elevation as determined by observation 
of the coast beaches, we should have probable proof that the streams of 
the land poured into the sea at those points. Thus far I have not been 
able to apply the method satisfactorily, in part owing to the rarity of 
known elevations in these valleys. Where the streams were large com- 
pared to the breadth of the valleys it is doubtful if this method can be 
applied with certainty. The broader and shorter valleys, off the lines 
of the glacial rivers, are the most promising cases for the application of 
the method. 

The following data give approximate elevations of the highest shore in 


484 GLACIAL GRAVELS OF MAINE. 


several of the valleys. The list could have been considerably extended if 
the elevations were known: 


Elevations of seashore in valleys of Maine. 


Character of deposit 
passing into marine 
fluviatile delta. 


Name of valley. Place of highest admissible seashore. See 
Marine valley drift. 
SACO ae ROE ere sae Standish, below Steep Falls - ---- ut Ese ores cer 200 to 250 
Dae are otek pee Sebago Lake-...--..--..--.. | 4. |bsessasece 250 to 260 
North Windham-----.----.-----= | Soy ale sSeeee 250-++ 
Little Androscoggin -.| South Paris - . Segre ee eee cope cosa ||soenc5 han: x 400 
Twentymile River. ...| Sumner and Buckfieid ------.-..-|..-.--.-.- x 8502 
Androscoggin .....--- Livermore Falls, or Jay .---..--.|.--------- x 375-4 
Sandy River..-.-.---. Farmington -..---...- ih SEIS NP x 440-- 
Carrabassett .....---. Newb ontlam die oer esses saree See eeieey x 450? 
Kennebec ..-.-.--.-.- Bingham or Moscow..-..-..------|.--------- x 450 to 500 


The Kennebec, because it occupies a deep depression and penetrates 
far north and west, is better situated than any other of the valleys for con- 
taining high-level marine beds. It presents many difficult questions of 
interpretation which it will require detailed study to solve. he sands and 
clays admitted as possibly marme in the above table have heretofore been 
interpreted by me as valley drift laid down at the sides of a broadening 
osar. The history of this interesting, because difficult, valley must largely 
be left an open question. 

It has been before stated that the upper or rarely fossiliferous marine 
clay passes up the valleys as the basal layer of what appears to be valley 
drift. Even if we grant the highest elevations given above for the sea, we 
do not reach the limits of the basal clay, which in places extends up to 600 
feet or more. 

Probably the most important feature of the valley drift is that the 
basal layer is of finer composition than the upper, at least until we reach 
the steep mountain valleys. Sometimes it is a fine gray clay, at other times 
a silt, but almost always it has a finer composition than the gravels and 
sands that overlie it. This condition extends considerably below the old 
sea level and is widely shown by beds undoubtedly marine. The valley 
of the Penobscot River west from Medway shows little of the basal clay, 


ee a ee ee 


—— es 


LOWER STRATUM OF VALLEY DRIFT. A85 


but there appear to be local reasons for the peculiar alluvial drift of this 
valley, such as its direction, its passing through so many lakes that would 
arrest its sediments, its large ravines or gorges of postglacial erosion both 
in rock and till, with terraces composed of the coarser eroded matter extend- 
ing for some miles below the gorges, ete. 


CAUSES OF THE RELATIVE FINENESS OF THE LOWER STRATA OF THE VALLEY 
DRIFT AND THE MARINE BEDS OF THE INTERIOR VALLEYS. 


The valley drift passes into the marine beds by not easily distinguish- 
able gradations. They are here treated together in order to avoid the 
necessity of absolute determination or distinction of one from the other in 


the field. 
THE LOWER STRATUM, COMPOSED OF CLAY, SILT, OR FINE SAND. 


1. We have already given proof that this sediment was chiefly of 
glacial origin. 

2. The average composition of the till is such that great quantities of 
fine glacial sediment demand the existence of great quantities of the coarser 
matter also, although it must be admitted that in some of the interior 
regions, as the upper Kennebec Valley, the local slates would cause the till 
to have a finer than average composition. 

The inference follows that at the time the finer basal clays and silts 
which cover the bottoms of the valleys were being deposited, there was 
also a body of coarser sediments being deposited higher up in the valleys, 
or in part, perhaps, in channels within the ice. The smaller glacial streams, 
perhaps, then carried little beyond the ice front except Gletschermilch and 
the finer débris. 

3. Fineness of sediment implies the presence either of the sea or of a 
lake, or, if above their level, a very gentle slope. Some of these basal fine 
sediments pass above any level of the sea that now appears at all admissi- 
ble. The interpretation is thus preferred that the land slopes were very 
gentle at the time the basal fine sediments were deposited. Such low 
gradients must have marked the time of deepest subsidence of the land, 
and I see no other assignable cause—remembering that the subsidence in 
northwestern Maine was three or more times that of the coast, or, rather, 
that the postglacial elevation has been such. 


486 GLACIAL GRAVELS OF MAINE. 


THE COARSER UPPER STRATUM. 


1. The fact that the till was only partially eroded from the outer islands 
proves that the retreat of the sea was geologically rapid, especially if, as is 
probable, the surf beat against the ice all the time of the retreat. to the sea 
margin and only once on the land situated beneath the sea at its highest 
level, and that during the time of elevation of the land. 

2. While we do not know the amount of early glacial subsidence, we 
do know approximately the amount of postglacial elevation. I assume that 
this elevation has been about three times as great in northwestern Maine as 
at the outer coast line. The moment this differential elevation began, the 
gradients of the valleys leading southward became steeper, and grew more 
and more so during all the time the land was rising (the apparent retreat of 
sea) to its present position. 

3. Marine glacial deltas are formed at the ice front. The presence of 
such deltas in the interior of the State within 100 feet or less below the 
highest admissible level of the sea in their respective localities, and that, 
too, at elevations of about 100 feet above the highest marine glacial deltas 
that lie nearest the coast, proves that the ice still covered all the northern 
part of the State at the time the sea had reached its highest elevation, or 
nearly. Indirectly they furnish proof that the greater subsidence to the 
north had at this time been already accomplished. 

4. The inference follows that at the time the sea reached its highest 
level (i. e., when the subsidence of the land was arrested) glacial sediments 
were still being poured down the valleys in front of the retreating ice. 
Above the sea of that time these glacial sediments formed valley drift; 
below that level, fluviatile marine deltas. During the differential elevation 
of the northern lands this delta would recede southward with the shore of 
the sea. The steeper gradients would now enable the coarser glacial sedi- 
ments to be transported to longer distances from the ice, where they would 
be deposited over the beds of finer sediments already spread over the 
bottoms of the valleys. Moreover, there would be more or less erosion of 
the coarse sediments previously deposited farther up the valleys than the 
basal clays extend, and the eroded matter would be transported nearer to 
the sea and often might reach it and help form a fluviatile delta where the 
rivers flowed into the sea. 


UPPER STRATUM OF VALLEY DRIFT. 487 


As elsewhere noted, these fluviatile deltas can be traced in all the 
larger valleys. The delta of the Androscoggin reaches to the sea, or 
nearly, as ought to be the case where a large stream continues to pour 
sediment into the sea during the whole time of the retreat. The delta of 
the Kennebec covered not only the basal clay of the valley with coarse 
gravel and cobbles from Bingham for many miles southward, but also all 
the fossiliferous clays from Norridgewock south to a breadth of several 
miles. From Madison south the delta consisted of sand; northward it 
became coarser. ‘The delta sand is not traceable south of Waterville. 
The fluviatile delta of the Penobscot is indistinct south of the mouth of 
the Piscataquis River. I have not been able to trace definitely the clays 
which naturally belong to a fluviatile delta of sand, but undoubtedly the 
finer sediments were swept out to sea and helped form the upper or 
sparingly fossiliferous clays. 

5. South of where the fluviatile deltas of the Kennebec and Penobscot 
rivers disappear as broad sheets there are low plains or lateral valleys which 
would be covered by sea water up to the time when the sea had nearly 
sunk to its present level. If these rivers continued to brmg down the same 
quantity of sediment as formerly, I do not see why the fluviatile deltas 
should not be prolonged all the way to the sea, or at least they should 
spread laterally into these broader bays of that time. 

Various reasons can be assigned for these deltas failing to be extended 
all the way to the sea. Thus, as the ice receded toward the north a larger 
proportion of the sediment might be dropped at a distance from the sea. 
The supply of glacial sediments would diminish as the ice melted. The 
flow of water may have diminished as the elevation advanced. As the 
gradients became steeper the sediment would be carried out farther to sea 
and would tend less to spread into the lateral bays. Parts of deltas may 
have disappeared by erosion. The net result was that the deltas were 
narrow, no longer extended back from the rivers, and are hardly dis- 
tinguishable from the flood plain. 

The existence of Merrymeeting Bay has a bearing on the history of 
both the Kennebec and Androscoggin rivers. Into this large lake-like body 
of water both these rivers flow. Both have formed delta flats near where 
they enter it. If there had been any such transportation of sediments 
when the sea stood, say, 30 feet above its present level, as took place 


488 GLACIAL GRAVELS OF MAINE. 


while the sea stood at high level, the two rivers combined would have filled 
up the bay, as I conceive. Yet the land slopes at this time must have been 
almost as steep as at present, and were much steeper than when the sea 
stood at its highest level. The conditions would be favorable to transporta- 
tion from up the valleys, yet the late deltas are comparatively small. The 
most reasonable interpretation is that the supply of sediment fell off greatly 
as soon as the ice had melted. 


SIZES OF THE VALLEY-DRIFT RIVERS. 


Professor Dana postulates in the Connecticut Valley a river large enough 
to fill all the space between the terraces—a condition inadmissible in Maine. 
The broad osars and the uneroded valley drift all pot to sedimentation by 
the rivers open to the air, as taking the form of rather level plains, not as 
high terraces bordering a deep central channel. 

The hypothesis that there was a greater elevation of the interior than 
of the coast region of Maine helps clarify some heretofore very doubtful 
points of interpretation. At elevations extending from 350 to 450 or 500 
feet are plains of valley sediments up to 5 miles in breadth, and in a few 
cases they are somewhat wider. If these great sheets are valley drift, they 
demand very large rivers. But if they are in large part marine beds, 1. e., 
fluviatile deltas formed offshore in bays or fiords, we do not need so large 
streams to account for them. From the sea margin back to the ice these 
rivers were dependent, like ordinary rivers, on the annual precipitation. 
Within the ice-covered area their waters were glacial. But the drainage 
systems of the ice-sheet did not conform to those of the land. Any attempted 
comparison of the sizes of the valley-drift rivers with the present rivers must 
take into account the amount of glacial waters that was diverted from one of 
the present valleys by glacial streams, or that was brought ito it. Such 
calculations are necessarily difficult. The valley drift is more abundant in 
valleys that once contained the larger glacial rivers—that is about all we 
know. 

Valley-drift time was relative. In each valley it lasted from the melt- 
ing of the ice until the supply of glacial water was all cut off. Whatever 
may have been the annual precipitation, the flow of the valley-drift rivers 
was not only that due to this precipitation, but also that due to the net 
melting or wastage of the ice-sheet. 


SIZES OF VALLEY-DRIFT RIVERS. z . 489 


Below Moscow and Bingham the sedimentary plain of the Kennebee 
is from 1 to 6 or 7 miles wide. The overflow stream from Bethel south- 
ward into Albany was a fourth of a mile wide or more. This was an over- 
flow of the Androscoggin River. Even if we admit the alluvium of the 
broader valleys to be fluviatile marine deltas, still we need streams capable 
of acting over great breadth and with velocity sufficient to transport gravel 
and cobbles. The breadth and character of the deposits demand large 
rivers, but I am not prepared to submit a quantitative comparison between 
them and those of to-day. It is probable that there was a greater rainfall 
then than now, if we correlate valley-drift time with a part of the career of 
lakes Bonneville and Lahontan. But we know neither the cause of the 
glacial epoch nor the cause of its termination. At present I leave open 
the question of the sizes of valley-drift rivers as compared with those of the 
present time. 


U. S. GEOLOGICAL SURVEY 


MONOGRAPH XXXIV PL. XXXVIII 


7 


ae . 
7 Momeni a \. 


« Round P. 


\ We, WIS IRL WE ORE 


eh) Wickerell 


\ 


S Little Welso, 


A.Hoen & Co, lith. Baltimore. 


MAP OF ANDROSCOGGIN COUNTY SHOWING LOCATION OF GLACIAL GRAVELS 


Scale 


ae 


2 19 MILES 


1893 


U. S. GEOLOGICAL SURVEY MONOGRAPH XXXIV PL. XXXIX 


| 
(PLANTATION | 


XV Qs ILMOT\ 
\ 
MONTICHYLL 0 


PLAN TATI | 


First Bel L, 


Second Lel L, 
GLENWOOD 


LANTATON : Dy Third Bet L. 


Ke 4p 


YARMOWTH 


A.Hoen & Co. Lith Baltimore. 


MAP OF AROOSTOOK COUNTY SHOWING LOCATION OF GLACIAL GRAVELS 
Scale 


10 IS MILES 
] 


1893 


U. S. GEOLOGICAL SURVEY MONOGRAPH XXXIV PL. XL 


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A. Page. 

Abbott, deposits in- 63, 124-125, 400. 401 

Acton, deposits in.....--.-----.--.-------------- 256, 262, 318 

Adirondack Mountains, ice flow in. ----------------- 417 
Agamenticus Mountain, features of ..----- ssesen seco 257 | 

Agassiz, Louis, cited.----...-..--------------------- 4,275 

Alaska, glacial conditions in..---..----------------- 273, 
280, 296-297, 300, 322, 355-358 | 

Albany, deposits in-...-------.----- 249-251, 252, 254, 258, 489 

Albion, deposits in-.--..------------------------ 165-169, 322 


Alegwanus River, deposits near ... 
Alexander, osar in -.---.---------- see 17 
Allen, J. A., cited -.--..- 20 55 


Alluvium, definition of - Ee 16 | 


Alna, age of deposits in. 393 
deltain=---- ~~~... - 457 

, deposits in... 168, 169 
Alps Mountains, glacial conditions in--.-.---.------ 300, 318 
Alton, deposits in --....-..----.----.---------------- 124 
AN HE, CEI, 0, Ssecono skasea canoes soesoodscossa550 452 
@SRORE) Wh. =o coos sosssoonsonooesSsesonssecescs 117-118, 369 
Amity, osar in-.....-----------+----.---------------- 80 
Andover, Mass., osar at -.---.----------- 217-218, 220, 358, 424 
Androscoggin County, deposits in-..-..--.-.--.----- 179, 
195-211, 213-215, 222, 224-228 

THAD OF soca senocasssostessccas o00 490 
Androscoggin glacier, moraines of - 274-275 
plate showing moraine of. --..- 274 
Androscoggin Lakes, deposits near S66 216 
Androscoggin Pond, osar near .--..----------------- 198 
Androscoggin River, age of deposits along----.-.---- 394 
Gol tin AMS ON Roo poo e soe eseaseseeeeosoncsase 487 
epositsyal on ges eeme een — eee ee 57, 

59, 63, 192-193, 209-210, 216-235, 323, 356, 381, 474, 478, 484 
potholes in 325 
ERAT, WAVER, OUCH eo seese Ss Seneca sseecoesensoboRess 1) 
Anson, deposits in ---.-.--.--.----.----- 179-181, 400, 401, 468 
Appleton, age of deposits in..-.------.-------------- 393 
GIGOOSMIS) 160 oa aeons cos oesonoceoscoscescacensss 148, 155, 156 
Argyle, deposits in..-..-.--.--..-------------------- 116 
Arkansas Valley, glacial conditions in. - -- 345-351, 356 
Aroostook County, deposits in..-.-.-.... 73-85, 93-94, 418 
WMD OF oscacocedcoacosgnacooemsogobdssocesenosasan 490 
Athens, deposits in-- soo UgAl 3783 
Auburn, deposits in..-...-.-- 225, 381, 476 
figures showing esker in...-....--.------------- 204, 205 
Augusta, age of deposits at...--....--.-.------------ 393 
deposits at....-.--....-....--------- 171, 172, 182, 183, 184 


Page 
Aurora, age of deposits in-....-..-...--..---.--.---- 393 
deltayitn <r -n)-eeeee sees ame ce nietesieeete 372, 374, 376, 391-392 
deposits in..-.-.. 88, 108, 114, 284, 318, 335, 430, 432, 460-461 
plate showing osarin -......--.....-----.-.--..- 414 
Aybol Stream, deposits along -..........----..--.--- 116 
Ayers Stream, osar along ..............--.......-.-- 115-116 
B. 
Bailey, J. W., cited 2 
Baileyville, osar in i7 
Baldwin, age of deposits at ....... Saas cos 394 
depositsinka.s-sseaee soe eee nee 246-248, 254, 334, 439 
plates showing osar in.....---......---------.--- 244, 246 
‘Bancrott, OSan Mealy na eee a- sec oe ceice mee eee eee ee 93-94 
Bangor, deposits near .....-...-...--..--+------------ 87, 124 
ispyet aes, CC PCM = orsecseses coon snbasooesseeones 73 
Baskahegan Lake, deposits near .......----..---.--- 93 
Baskahegan Stream, osaralong.......--...---------- 83 
Bathypotholesimeanene=mecsesee a= eerie eae esse eee 325 
Bauneg Beg, features of. - = 257, 262-263 
Beach gravel, character of..........--.-.------------ 41-53 
fossilsnmleeessee a= === 53-54 
relation of till to - 282 
Beaches, elevation of ----- 481 
figure showing ancient.--....--. 4 46 
occurrence of raised ...--..-.-....- 3 300 
Beddington, deposits in .......--.--.-----.---------- 392 
QSBIE TEN sos sco cosas sec oeesoonassoocesosesac laeese 100 
Belfast, deposits at-. 137, 138-139, 143-145, 318, 321, 328, 382, 354 
Belfast Bay, deposits near ..----..-..--- 187, 138, 144-145, 382 
Belgrade, age of deposits in ---.....---...--.-..----- 393 
GIETNOS TN ooo sondcons saencobosoesssarseesoasses 181-185 
Belmont, deposits near --.---.-...--.---------------- 144-145 
Belmore, James, aid by .----.---.-.------------------ 95 
Benton; de positsnn ame ness =e aaa eee 168 
Berry, J.S., aid by-. 198 
Berwick, osar in---- 262-263 
Bethel, deposits in --- 248, 249, 252, 356, 405, 489 
Bingham, delta in ---.-------------- se 487 
deposits near.---... - 484, 489 
Bitterroot Mountains, glaciers in ---. s 351 
Blackwater River, deposits near ....-..----.-.-.---- 74 
Blanchard, age of deposits in---.....---..--.--.----- 394 
(EOMMIIM ososacoesoesseserocesencS secacaocanss 124 
MOTs CD ACIS Me eter ale ale eee el eer 173 
TiC] ECHOING TN. oe emnoabeansdocesosooncoSsene 23, 266, 268 
Bog Brook, figure showing osar along...-....-....-- 442 


492 INDEX. 
Page. | Page. 
Bonny Eagle, deposits near ..--...-.--.------------- 255 | Coastal region, deposits of-....--.-.---.--.---------- 379-413 
Boothbay Harbor, beach gravel near .--..----..----- 51 | Codyville, age of deposits at.....--.-.--.-....-..... 393 
Bowlders, occurrence of.....-....--------------- 284, 333-337 enositsmeanieemiee ethene ee eee eee eee 77, 79, 83 
Bowdoin, figure showing esker in .-----...---.------ 383 | Colorado, glacial conditions in..--..--.......-..---.. 338-351 
OSAT AN eee ence ma ese aise esas eciee ieneen > 186-187 sedimentation in : 17-18 
Bowdoinham, deposits in 55, 171, 172-174 | Columbia, deposits in 5 88-90, 
Bramhall Hill, Portland, figure showing landslip at- 232 101, 110-112, 320, 388, 406, 425, 434, 487-439 
Brand OnuiVaiaio GO POSULS elles ee eee ls =e eee ae 27 (GMOS AO WEEUA 2 se sese2esassoeseesccoeaees 65 
Bridgton, osar in- . 244-248, 439 | Columbia Falls, deposits in-.-- 88-90, 94 
Brighton, esker in. --..---- 173 | Connecticut Valley, glacial river in - ~ 488 
Brooks, age of deposits in. 393 | Conway, N. H., ave of deposits near....-.-.--.---..- 394 
Ge POSTISahN poasgassadsusEbecbooSueEnepAeaeaacsone 138, 143 depositsinears-4-saecesbe ostesccceseaeeee aes 256, 263, 149 
Brownfield, deposits in...-.-..---.- 254, 256, 257, 258, 259-260 | Corinna, age of deposits in...............-- Bree aay 394 
plate showing osar in med, 254 MepositsHiny\ lessees ea clseaeeceeceecss 189-142, 423 
Brownville, condition of rock in ..-..-.....-.--.---- 7 | Corinth, figure showing deposits in...-..-.--.-.--.. 380 
deltain.......---.. SOE a UC Hot ontoacpacrdsenaccde 459 OS ATH DS top earios seach case aoe tne eeene esse eee 129, 131 
preglacial deposits in ..........-..-------. Ene, 28) (Cornish) deposits in yas= seem eee eaeae= ese eiaaaee 256, 257 
Brunswick, deposits at -..--.-..--.------- 55, 56, 193, 200, 203 | Cornville, age of deposits in......-..-...... ae Sere 394 
MOWNOES Bins sossosccoraceoopaadetsnoondcocecesece 325, GENT Sac caomascoaseacss -- 171, 400 
Buckfield, age of deposits at.-..---..--------------- 394 | Cove gravel, occurrence of. 41-53 
depositsyn seer oe eesae nee ieee ert sections of -----..----....-.. ---- 42,45 
iBuckinanypkaid bypass ee eee eeeeee nee “Crag and tail,’’ phenomena of - 31, 308, 352-353 
Bucksport, deposits in.-.. Crawiord "deposits ames. a) aoe nena en eeeesa eee 86-88 
plate showing osar in - Crevasses, formation of .--...-.---- 310-316, 323-324, 401-402 
Buckston; Ceposits mean sees aaa eens Croll james, cited aso. seer hess eee eee 306 
; Crooked River, deposits along ...-....-..--.-------- 249-253 
(Oh Crystal depositewnl= sens seen eee ce eeeseeeeeeee 96 
. rie Cumberland, deposits in .........--..---.------- 229-232, 234 
Calis, dejamiis Tear See MM EE PCIE 1 hater Canis oa Cumberland County, delta plains in ..-...-..... 374, 375, 387 
Ca ee ae YG Ae eis deposits in .....--2..---- 95, 189-195, 200-201, 215-248, 255 
Cambridge, deposits in -.- -- 148, ey wR Of 450 
Canaan, age of deposits in ...........-.---.--------- SRA e 
deposits in..---------- Testo oo) ee ah 
Canton, erosion near 66 " 
figure showing osar in ............-..-----.-.--- 442 ° 
SPO <aos5doosca9 has saoneeseanscss 206-210, 212, 381, 442 | Dana, J. D., cited... -. 8, 28, 54, 67, 68, 328, 329, 424, 488 
Cape Elizabeth, deposits near....--..--..-.-.-.----- 215-216 | Danforth, osars in 
Carmel, deposits in.--..---.-....-.---.---...--.- 132, 186, 380 imillltie 52 430 
figure showing osarin .........--..-...----..--. 183 | Darling, A.J., aid by--- 95 
section across osar in se 182 | Dead River, deposits along.-..-----.- panes WEES 
Carrabassett Valley, deposits in---...... 180, 356, 401, 405, 484 | Deblois, aze of deposits in.....-..---- es 393 
CanypPlantation; osannnpnes sees nent eee ae 75, 80 elfasiiny 2222-32522 tae aeeee eee eee eee ee 374, 381 
Carys Mills, osarin.-----.----.---..-..-----.-.---.- 74-15 depositsyinessseeee sees 101, 110-111, 114, 284, 406, 432 
(CHEM, OSHIP TM 5 o520 ssonencnnsoot os lose sacessseeossras 235-238 erosion near. 2. ~ sweets Soe ees eenee eee eeeeee 65 
plate showing deposits in .......-.....----.---.- 320 Dedham, depositsimence= eee tee eeaee eee eee 121 
Centerville, deposits in ------ 90,91 | Deering, age of deposits in.......----....------.---- 393 
Chaleur Bay, deposits near .-.......---..----------- 92 L130 Detaasicind ohn citedeere sarees ese sere a eee eee eee 3 
Chalmerst Rn, Cited) ease -nan emo ee a= eae 50, 70, 295, 418 | Deltas, deposition of ...........--.......-------- 321, 469-470 
Chamberlin, T. C., cited ---. 14, 266, 280, 284, 431, 446 elevation of 222ee See see stink eaeeeee eee eee 482 
letter of transmittal by.--.-..--.--.----- XL melation'siOL: seme Gaeeenet ees een eee eee teres 455-459 
Guotediae yen neat sere onemenen 359 | Denmark, deposits in -.....--- . 245, 246, 252 
Channels, enlargements of ......-.---. --- 317-319 | Dennys River, deposits near -- as 78 
TOMTANTY OOM Ole ccopaoseisoosgodse soovassssarsoacaecs 308-317 | Dennysville, age of deposits in.. 393 
Charleston, gravelin....-..--........-.......--..-.. 129, 131 OSAP My sac’ seems nntse i 59 
Charlotte, deposits in........---.-...5..-2------e--ee 73 | Detroit, deposits in... - 145, 380 
Cherryfield, erosion near ..----.--...-........-.-.--- 65 | plate showing osar in --...... 146 
Chestervallexos ape eres atest ete eit 196-200, 381 | Dexter, age of deposits in..-.-....-.-...--.---------- 394 
ChinaydepesitShineereseerereresstesises= eee aan ere 165-169 BUSOU) THY o-oo coos op ooo scoscooocacisse sescenea 139 
plate showing deposits in -.......-.------....--- 168 | Dixmont, age of deposits in .-.....---..-..-.--..---- 393 
plate showing mesa in -----------.---..-.-...... 454 GUST soa recae a5 se ssc anacesstansseosssoesteses 459, 469 
(QUEVIgS, WE IP AMG? soecioonssy = dneeeboasones se ssecae 173 TRANG) THN sceigciocinaseassagssessdteepeooecoeneso> 146-147 
Clay, character and deposition of .---. 54-58, 170, 180, 468-469 OSPIO MN Sodosscocs snodcdaeciosecseéeosbeness 140-142, 310, 423 
Clayae Nee veo eltannien eee nee see ee ee eer eee eners 401° | Dover, Me-, deltain- <=" 5 -- 2). - one-one see nee ee 435 
Clifton, delta in. - 391-392 osar in -- 406, 460 
deposits in .....-.- - 119-120 | Dover, N. H., deposits at. 263 
plate showing osar in - bac 120) Dresden) deposits sine seereeanne esses see eee 171 
Clinton, deposits at..........--. 168; 171, 172, 380; 382, 429,468 | Drift, character of.--.--- 22... -ceneecncccnsan- 14, 265, 470-489 


INDEX. 


Page 
Drift, definition of ----------.--.---.------.-----..-. 10, 16 
IMG) Mindn eps onsneecooscuneocoescoDaDoLtoncasnes 22-26 
SNOUT HOM OH «6 GosanSocoocUsQUessocdacendaeson 15 
transportation of..-..-..------------..---- 10-22, 431-432 
(See also Valley drift.) 
Drumlins, formation of..-...-...-..----------------- 280-282 
occurrence of....------.--- 32 
Durango, Colo., moraine near --. ---- 342-343 
Durham, deposits at ....------ 
plate showing deposits in - 
Dyer Plantation, osar in -.-..- 
Dyers River, deposits along..-...--..--..--.---..--- 164 
E. 
Eel River, deposits on..-..--.-..-.------------------ 70 
East Bowdoinham, deposits at ..--.-.---.------—--- 55 
East Branch of Penobscot River, osar near ...------ 105-106 
Hastbrook, deposits in....-------------------.------- 117 | 
East Brownfield, delta at-.-...-...---...------.----- 459 
East Lebanon, osar at........-.-.- Rate cts e ct cise ome 262-263 
Mastweimermore Osarwie sees ere eas e-em 196, 199 
East Machias, deposits at..-..-- . 85-86, 87, 400 
East Machias River, deposits near. - . 86, 87 
East Mancos River, moraines along 329 
East Monmouth, deposits near..-...-..--.- 379, 451 
East Newport, osar at Sp -- 139-140 
East New Portland, deposits near........-----.----. 356, 474 
MLOLAINES MOAT eee seaatee ese mies eee lee er eames 419,479 
East Troy, kames in --- 142 
East Vassalboro, deposits in --....-.--..--------.--- 468 
Edes Falls, deposits at ......-----........--........- 251 
Edinburg, deposits in .........-.......---.---------: 116 
MOMS OSMAN sae ee ee eae ere 79-80 
Effingham, N. H., deposits near......-------.-:------ 256 
Ellsworth, eskers near.--..-..-- = 121 
Embden, deposits in -.-. . 179-181, 476 
Emerson, B. K., cited -- ase 470 
Emmons, S. F., cited-.-- . 345, 348, | 
Enfield, drift in.....-- f 432 
CROP MEheseaacocescikbS chp senorosqe tens cSSoseasscen 107, 113 | 
plate showing osar near.............-.---.------ 108 | 
Englacial débris, quantity of.............---.--.---. 275-277 
Englacial streams, action of-.-.-.-.---.-.----.--.--- 296-297 
COREE § coasanSbeeddeneadseaeacoso0obno 297-301, 308-310 
Epping Corner, deposits near..-..--...--.--..------. 111, 112 
ID ROSNY, CE TEMINOM OE oo son6~secesemunosecasnesesosnoe 27 
TAREE Geb, Oinsassoccossansoomesecnsecos sao 35, 359-360 
features of .-...--.. . 361-869, 448-467 
Estes Park, glaciers in. -- ----- 330-351 
Etna, deposits in .-......- -135-136, 141 
Exeter Mills, deposits at.--..-.--..----..--..--.--.- 132, 427 
section across OS8ar at.--..---.--.---..---.-.----- 133 
é BE. 
Fairfield, deposits in ------.---.-.---.-..-.----.--.-- 171 
Falmouth, deposits in.--....-- = 229; 231, 232 
Farm Cove, gravels near -.... -- 92-93 
Farmington, deposits in-. - 362, 484 
Fayette, osar in - -- 196, 198 
Forest, till near --- 430 
Fossils, elevation of. 481 
occurrence of ......-.-.---- 53-54, 56, 286-291, 374, 379-352 
PEG TreL TN CUTTS C Y) OS US LN eyelet ete leaflet etal eat telat 117 
Franklin County, deposits in--.. 187-189, 196-200, 205-206, 210 
HIE) Os - naccogsocososaguedeesos9es5590 0900 26 950500 490 


493 


Page. 
Freeport, deposits in ......--.-..------ - 200-201, 369-370, 379 
Frontal retreat of ice, map showing .--.------------ 392 
CHIEOIS Ol oaconce dosnemo~ngangogmsdanances 390-394, 401-403 
Fryeburg, deposits in ..-.....----------- 252-253, 256, 258, 261 
Fuller, C. B., aid by 53 
WG! socsostosossoonesens ssoneree seesensesceceses 287 
G. 

| Gardiner, deposits at---....--..--..-------------- 55, 171, 172 
Gardner diohmyai di Dyan aeemeeeeae ose sise enema 95 
Gardners Lake, kame near .........-.---------.----- 85 
GarlandWdel taper sae setae eee teers eae 435 
GIG DO MI Tin  eacbostoncebomeconoaonbosases 126-128, 330, 430 
QROMOM Wi) coeacacomovoswsosecostessorsasesesenes 297 
Geer Gerard! decitede nace ae -imien-eie enn ciee =e 480-481 
GUN - ospccosomsusoccouRso sseascuDoooROSSesese 481-482 
Georges River, deposits along 147-148, 
154-157, 361, 384, 391, 430 
Georgetown Island, potholes on...---.-....--...---- 325 
Gilbert, G. K., cited ---.......-- -- 47, 400-401 
Gilead, deposits in .-.-.. - 356, 450, 476 
plate showing morainein..-..-.......--.----.--. 274 
| Glacial period, precipitation during..............-.- 292 
_ Glacial streams, action of -...-.------------- Berea 291-292 
EWA Mince onbscb as dcodbsondsuendenacauSuconeecans 292-294 
Glaciers, drift forms due to..-.........--.-.--..----- 25 
transportation of soil by--.--.--.--...---------- 20-21 

Glaciology of Maine, chronological list of publica- 

HONS Ol - so.o- Ssceseodsnseaootoossoccsenoescine 2-4 
Glenroy, Scotland, raised beaches at .-.-.------..--- 300 
Gloucester, deposits im .---.-.-----...-......-....... 214 
Goldan, Switzerland, landslide at. 10 
Gorham, Me., age of deposits'in. .-.....-..-.---..--. 393 

deposits in-----.-.---.-_.-- ---------- 237, 248, 244 
Gorham, N. H., deposits near-..-.--- 210, 216, 248, 356, 405, 450 
Grand (Schoodic) Lake, osars near mn 
Grand (St. Croix) Lake, bowlders near...-.---...-.-- 75, 335 

OR EYP TEBE = 226 Seton escotScoacoonsesocoosossccce 75-76 
Gray, age of deposits in--------.----- 3 393 

CEPOSTLSMO eee eee ece eee eee 227-230, 232, 234, 238 
Great Aletsch glacier, action of ......-.-..--.------- 300 
Greene, deposits in..-.-..---.--.-- ceceaocrioscons 197, 200, 201 
Greenbush, age of deposits in .......---------.---.- 393 

QGTDOSWIE Tl. scogesssemsoasesneesso5e 107, 114, 318, 320, 427 
Greenfield, age of deposits in----.--...-..-.---.----- 393 

elitarimses seats socials aiece veel emcee cere 374, 391 

deposits in - 107, 108, 114 
Greenland, glacial condition of. ---- oie 264, 

269-270, 273, 294-295, 308, 322, 439 
Green Mountains, direction of ice How in .....---.- 417 
Greenwood, deposits in.-..........-..-..------------ 233 
Guilford, deposits in.--............-..-.-------- 126, 400, 401 
H. 
Hague s Peak, glacier on.........--...-------------- 351 
Hallett glacier, character of --.-.-.-.......-....--.. 351 
Hallowell, deposits in 
laleTVbIA, (OL10,) GIL c= Gonnaeses casacHasasoosoesncesn 
Hammond, Ji H., aid by ------------ =. 2 263 
Hampden, deposits in----......--.-..-.- 122-125, 181, 184, 136 

figure showing deposits in.---.......---.-.----- 381 
Hancock, deposits in.-.--.-- Beau 120 
Hancock County, deposits in. 92, 117-122 

TAO OW coosoensesonsoce 6 490 
Harmony, age of deposits in --...-..-....---..-...-- 393, 


494 INDEX. 
Page. | IK. Page. 
Harmony, deposits in--....-..-.--.-...--.-- 148),159)171).1'73' |) Kames, definition of.--\.------ -.-2- 2s ene eee 35, 359 
Harpswell, deposits at .-------.-....-.--..-....----- 57 HCMC Obs soaceraessoesaceesedaozesassa 368-369, 448-467 
antfordeSkersiimie ee -- see = ee nina -o- =e 210-211 formation of 330-333 
Hartland clay meas see seine eee = neice eee 172 | Katahdin Iron Works, age of deposits at.-----..-.- 394 
(IG NO STS aI <5 58 ea Geancan on penBenean 173 deposits at 134-135, 419, 474 
GHOST ~ --2 5.555 os6aobunepaeusebessSSouss=es2 429 rock weathering ab. --—- ee enn 8 
osar in .... - 148,152, 156,173 | Katahdin osar, course of.- -. 104, 117, 284, 372, 374 
Teta, Se WW, GeO yobs seca sass eeseaseseseess 95 | features of .-.....--. -- 335, 381, 400, 430, 432 
Haynesville, osar in---- 81, 84 | plateshowinle ce aches eeee eee eae 108 
Hebron came saints ae = a eee eet 214 | Kenduskeag, deposits in 255 Ie ey ey 
plate showing esker in. -.----------------------- 214 | Kenduskeag Valley, figures showing deposits in---. 132 
Hermon, deposits in..---.---.----.-------------- 130-133, 427 | Kennebago Valley, age of deposits in---....-.-.--.- 394 
section across osar in.--.--.-----.-------.------ 133 | TREES TS ore pee enene Eos encaeessascotecnenses 253 
Hermon Pond, figure showing deposits at.--.-.----- 380 | Kennebasis River, deposits near .-..--.---.--.---. -- 91 
Tloree yy inl Me ces Sao ceHoccanac aso SoUoo esp esScreonse 430 | Kennebec Bay, section across moraine near ---..-..- 51 
Hiram, deposits in 54, 257, 259-260, 467 | Kennebec County, deposits in..-.-.--..---.-----.-- 165-174, 
plate showing deposits in ..----.--.-.----------- 258, 452 177-179, 181-187, 189-195 
Hitchcock, C. H., cited 2, 490 
3, 6, 32, 41, 50, 54, 63, 68, 242, 266-287, 295, 360 | Kennebec Valley, age of deposits in . - 394 
OOH oo seo oo sdenonsss osssnscess on oasossacours 74, 187 composition of till in...--.-------- 485 
Hitehcock, Edward, cited --- oF 424 deltaine-------=-= 487 
Hodgdon, osar in ---------------- 3 75 | GET IHMIGW seo rsomscsesesos cooSseresssosSteseoRS 56, 
Hogback Mountain, erosion near..----- ae 430 | 57, 63, 64, 171-179, 181, 185-186, 323, 400, 476-478, 484, 489 
figure showing eee 153 potholeshin<s.- 232 se22 -hscseeseeoscasease sees 327 
TNO nose sees nb ose ceo seceLcqsocescobeacSeaaeses 151 SOW BOWIE sss occosossansasdassesscsconeos 
O8ars Dear! 2s222t2ecsee ces ee eccezese cee a= 152-154, 157, 331 | Kettleholes, features of..---------..:---------.----- 
Hogback Mountain Pass, plate showing ------------ 152 form ation! ofe) seen 2 nee eee ee ee eee 
plate showing osar at -.-.---..-.-.--------.---.- 154 | Kettle :noraine, features of-.-.-...----...------------ 
Holden; depositsins-2- -* \ne soe ee ene 121-122 | Keystone, Colo., moraine near._--------------------- 
HiolmesEzelielwcihedee esse e ae aee ease sere e eee ee 3 | Kezar Brook, deposits along.......-..------------+- 
Holst, E., explorations of.-..-..--..-----.----.------ 269 Kibby Stream, age of deposits along..-- 
sHoulton;osarmesmrescer seers sae eee sae ae ee eee 73, 77, 80 horseback near 
Gili see eee ee sermane se NUL wat one wee ercte 430 | Kingman, deposits in. 
Howland, deposits in | 97-100, 102, 381, 425, 434, 437-439, 451, 458-454, 472 
Etunitin&tonyeeet Cied essa eae ae eae =e eens 3,233 | Kingsbury, esker near ae 173 
| Knox, erosion near..-.----- aA 66 
i | Knox County, deposits in-- - 147-148, 160-163 
MaAplO, 2-7 Woee cesta Sete ae cee en aera 490 
Ice, map showing frontal retreat of...--.------------ 392) Kossuth Oe posits Mea. === sere eee eee reasons 93 
retreatal phenomena of. .-..----.---------------- 390-394 
Icebergs, drift forms due to ----.--------------.----- 25 
transportation of soil by --.--------------------- Pail L. 
MGD lores, Grate HOSES alae aera ne a aaa ee : Lagrange, age of deposits in-------.-----.--.--.--.-- 393 
transportation of soil by ------ 
‘ ate eg GRERO MW = 325522 seosoncsasesocsoocossoessososs 123-124, 400 
Idaho, glacial conditions in-.---- Lak Sie ‘ , 
3 2 é ake Anburn, fossils near---.------.---.------------ 374 
Tnidhans Ride e, Mass: feauanes|of aes Lake Bonneville, Utah, beach gravel near -------.--. 47 
structure of 424 eanditionctad 489 
Interglacial period, possibility of. - 284-291 | Lake Lvanh ea 1 gla AMAR Tae SE ee line a 
= | Lake Ivanhoe, moraine near 2 349 
Trovathol, Collen Hepasnis ai Be Lake Lahontan, Nev., beach gravel near 4% 
Island Falls, deposits in-...-.-...---.------ -- 81, 84-85, 96 | iti % 4 2 SAMMES SEINE tat &) 
Isle au-Haut, beach vravel on ----.--..-------------- 48 | L Coon, 2 Magiehs CRED MMR Pa EGER ce IP = 
SODASES, (COULSCS) Ofer nee ee pene eaene at eee 481-482 Oe Roe OF OTHS Bi. , ue 
du | deposits in 2h -- 119-120 
5 | Landslips, transportation 10-11 
, drift forms due to ..---. -. 25-96 
JacksonwOclecitedieea ean ean eee nena 2, 6, 41, 54, 63,68 | La Plata Mountains, glacial conditions in - - - 338-340 
ACISSOUMES RCTSMN ees eee eee eleanor 138 | Las Animas Valley, glacial conditions in......-....-- 340-343 
CEA EYRE Oi) GIG OSS) Mae oe ore Sigg sees sas0 394 | Lead Mountain, deposits near----.--.......-....--.. 392 
(WSUS Tint, Sons Sos ceododess=soszsuesosose. 205, 210,484 | Leadbetter Falls, horseback at -............----.---. 187 
plate|showing esker in------ ---------- = so an: 214 | Leadville, Colo., deposits near -...--............. 345-346, 348 
Jefferson, deposits in.-...-.-.--.--.------.---------- 1 638—164:5| eebanon Osan see seeeeea eae n seeker te eee eee 262-263 
Jerusalem, deposits in ...--....-.-------.------.---- 187-188 | Leda clay, occurrence of ..-.-...--..---.-------.---- 55 
Jo Merry Lake, osar near.---.-.-------- THE |) bees We elie) soc ooo a assoneoen ea esoseseseoe odecomsd 56 
Jonesboro, age of deposits near -.-----...-..---.--.- SHB] ILCs NOSE ek ee oe ee eb eocoo sooedancos 99, 103-104 
deposits!ine esse ese eee 88-90, 91, 94, 112 plate showing deposits at - 104 
Jonesport, age of deposits near .--.-.--.------------ 393 | Leeds, age of deposits in - 394 
deposits in..---..-- ateh ts meee ese see ome 320, 382, 388 el tas in’. 752 sas aoe = se esaseaises tacos eeeene 480 


INDEX. 495 

Page. Page. 

heed § OSAr AM -semelonciseccmeoemeciacateaacs sense 196-200, 381 | Massives or osar mounds, features of ....-.-.--..--. 369-371 
Lenticular deposits, occurrence of....------------ 32;,382-386) || Mathew,\G. ., cited. ...-----2 5. =. ----nanewccwecn es oe val 
Levant, deposits in....-...-.--.~ ---- 131,132 | Matinicus Island, beach gravel in............- 47-48, 282-283 
Bectionlofosaniney epee esate eee ee ean 132 | Mattagordus Stream, osarnear.-..-.........----.... 99 
Lewiston, deposits near , 201-205, 209, 323 | Mattakeunk Stream, deposits along .-.............- 103 
POSSIUS|Abpenes ade ee als orlete eine ale eee 374,482 | Mattawamkeag River, deposits near .....-_. 82, 93, 98-99, 103 
Liberty, age of deposits in noise 393 deposits near branches of........-...-------.--- 81, 96 
depositsiin ees eee ne ee eee eaaeee eee oats 1535-158 osar crossing.------------ ... 437-439 

Dai Tye yO SANY CAT esas etal ote eee ete role 135,414 | Maxwell, D. F., aid by- - 95, 100 
Limington, age of deposits in ..--..--------.--.---.- 393 CiLedis Sc Ae ene ee See pea fs 73 
GEKOSAVN o- oSeasses Sooke 5 so 2sdoosneosesanone 254-255 | Mayfield, eskers in ...-....-.... a 173 

fie wes Ho wan Py Osama sesame see ae ean PEAS |) WAKE CE MY dy@ueal <4 escecganecencsscoces M 284 
Mincolny Osan ines see ase a ce eee ee 104, 107, 114,400 | Mechanic Falls, deposits at ................- _.. 213-214 
Lincoln County, deposits in........--..----- 163-164, 168-170 | Meddybemps, age of deposits in ..-...-.....-...---- 393 
WED OF s2scaconeessesaessoseraevsseossetorst sess 490 OS DEEN GA eae ee 78,79 
Lindahl, J., cited - 270 teMedtord idepositsnmyeesss= esse =eee eee eee 122-125, 131,134 
Linnevs, osar in -.--.- 80 | Medford Ferry, figure showing osar at.........-...- 123 
Litchfield, deposits in -..-.-.-------- 186 | Medomac Pond, deposits near 162, 163 
Litchfield Plain, date of deposition of se 393 Medomac River, deposits along .---..--. 361, 382, 388, 399, 409 
features! Otiscosaes- eee tose aoe 368-369, 452 | Meduxnikeag River, osar near ........-.....--.----- 75 
Little Androscoggin River, deposits along -.----- 63,476,484 | Medway, deposits in ...-...-....-..--.--.--. 105, 106, 115, 484 
TOMIOMWS Wo ocsoq5s6d5 sd 2dsanoaspbosrebsosbes000 327-328 | Menana Island, weathered rocks on..........-.----- 23 
Little River, deposits near .-----.....--.___..--..--- 92 | Mercer, deposits in.-..-- 184-185 
Livermore, age of deposits in -..-..-----.-----.----- 394 | Mesas, features of ..-......------- -.- 369-371 
GOSH NEW 22s eso sacar sa esssSooeacseseezese 66 | Messalonskee Pond, deposits near. - - 182-185, 184 
OSAT Ma seciae cis aw eee ceisek Sa eee 196, 199, 207, 208,442 Milford, age of deposits in ....... 393 
Livermore Falls, deposits near ..-..-....---..------- 484 | Milinoket Lake, deposits near ......-......- 116 
Lockes Mills, deposits near .-..-.-.....-.--.-----..- 233-234 | Milo, deposits at.--.-.--.-.....-..---------- is 135 
figure showing deposits at .-.. 12 | Milton, deposits in 435, 442 
figure showing stratification of sand at 12} figure showing) Osan in).-2-22--s-2- 4-68 s-acecee 442 
Lower Chiputneticook Lake, osar near --.-- 70 | Minot, deposits in 214, 381 
Lucia glacier, features of ...-..----.- 445 | Mississippi Valley, glacial conditions in ......_..--. 284, 288 
Iuyell, Charles, cited ..--..---..----.. 300 WU a a ose ace Re op kecoacesmeRoo sod bencaseeS 34 
Lynnfield, New Brunswick, deposits near -..-......- 71 | Molunkus Valley, osar in --...-2-....------------- 96-97, 437 
| Monhegan Island, beach gravel on .........--.---- 41-47, 281 

weathered rocks on. - 93 

M. Monmouth, deposits im -----02-2-2-0-2-02soeees 190-191, 

Machias, age of deposits in-..--.-.....------------.- 393 Doles! 193-194, 199, 377, 379, 407, 451, 460 
heachrrravel nearsees ce seue te see nema ewer ceeee 49,51 | GLHOSRO RN S292 ag ascnso SoC Sear Opt opasater acon 430 

de posttay ii sheets ee tee gated en wan 85-87, 400 | Monroe, age of deposits in - 5 393 
Machias Lakes, deposits near .--...-..-..------.---- 94,95 deposits in .-----..-..- --- 137, 138 
Machias Valley, age of deposits along -.-----..------ 393 plates showing delta in----.------..... --- 336, 452 
deposits in ew 83 | plate showing osarat.......-...:-..... 3 376 
Macwahoc, deposits in ........-....---+--.--- 7,102, 437-439 | Mont Eagle Plains, date of deposition of -..-.-..-..- 393 
iiadisonydeltapinsas esse eee eee nee =e ea eae 487 | deposits WTO B OE PRECIO SEPP C Se OCC rast eesos 94 
deposits in .-...- S my - 179-181, 400, 468 | Montville, deposits IN 2----- 2-2-2. 154-157, 322, 331, 430 
Malaspina glacier, features of-. 355-358, 420, 421-422, 467 OHO Gromer nese aeoecccacscsasaRcodqscDasesoRe 429 
Manchester, eskers in - --- - 183,186 | eID. of region near 151 
Manning, P. C., cited -_- 325 | section in -. ~~... -+.+. 2-22.22 2222222 22+-- 222-2 ee 152 
Mariaville, deposits in | 173 
WIRING Cle) MEH OP oaascecaescneescooneeescedosbens 58 | osar near.....---.--------------- 125-131, 132-133, 400, 460 
Marine deltas, classification of .........------------- 371-373 | Moose Pond, deposits near_.----.-. ...--.--.... 148, 171-172 
GLE WETLO LING fle Ee ee eae ct cy eh analy oak 482 | Mopang Lake, deposits near....--......-.---------.. 95 
TOATUTOS: OC ee eee eee one a et eae 371-376, 378 | Moraines, composition of - --- 270-284 
OLiGinlo tees aoe ema au 373-374, 375-376 detinition of------.- --- 20-21 
Marine deposits, character of....-..----------------- 41-58 features of ._- : 398 
MOLATONFOL TIL tO eee seers oc ec eee 282 | Morrill, deposits in. - 144-145 
WMamiontd @pos Itsy nese eee eee eee eee 85,88 | Morrison Pond, deposits near - 109,113 
Mirjelen-See, Switzerland, character of.......--..--. 300,313 | Moscow, deposits in .......-.--......-..------ - 484, 489 
GHSODMIED Oh conaccecoosecseeeoce 420 | Mount Desert Island, altitude of.-.........--- 6 408 
Marr, J. B., cited ..-.---.--..- af 270 beach gravels on.-.--.....-...----.------------- 48 
Marsh Stream, deposits along....-.---..-------- 138, 139, 143 height of ice sheet at---....---..--..---..------ 295 
Martin Stream, deposits along - - 140-142, 143, 207-208 | Mount Katahdin, altitude of...---.................. 40S 
Masardis River, deposits along.-.....---.-----.----- 362 height of iceisheet/at- ~~... --- 8-22. eee eee 295 
Masons Bay, deposits near .----...-....-.--------- 91, 94, 112 Osar near 104-117 
Massachusetts, glacial conditions in...-.-....-..... 358, 470 weathering near 267 


496 INDEX. 
Page. Page. 
Mount St. Elias, glacial conditions on......-.-.-.--- 355-358 | Orneville, age of deposits in-...-...............----- 393 
Mount Vernon, esker near ..-.-..-...--------------- 195 OS ATA joyce ee lelcetc oie lapse ote AOE ee SST SEE re eto 400 
Mousam River, deposits near........-.----- 256, 259, 262, 263 | Orono, deposits in -.....-.-----.----.--...----------- 124 
Muir glacier, features of..........-....---.-- 280, 355, 420, 467 | Osar-mounds, features of........-.--.--.-----..-..-- 369-371 
Munjoy Hill, Portland, deposits on ........-.-.----- 215, 283 | Osar terraces, features of. ---.-~-- <=. 2.22 - =o e anne 440-448 
FOSS Stones se ses ae eee ae eel cic tee meio ees 53-04) | (Osars) definitions of)--- = 2 - eee ee ee eee nee eeneei 35, 359 
section across 2 32 features of --.. --- 361-369, 376-448 
Muskingum Stream, deposits near. 154-155 formation of . -. -- 330-333, 423-425 
Munson, condition of rock in..---- 7 Stratification! of --2--)-esj-ee eee eee oe eee 423-425 
Musquash Stream, osar near..--...---.------------- 90-91 | Ossipee, N. H., kames near - E 449 
Otis, age of deposits in... : 393 
N. alten kis ts te. Sak Gale gas ete tee ees 391-392 
Naples, deposits at-......-- Ree acer eee aes 240-241 deposits in .-.-..-.---++------ +++ 2222s eee ee eee ee 119, 120 
Narraguagus River, deposits along... - 88,101, 110,114 | Otisfield, deposits in ....--...-...-.---.------------- 251 
Nevada, beach gravel in..-...--.--------------+----- 47 | Ouray, Colo., deposits near -..------.---...--...-.--- 344-345 
Newburg, delta in..--..- i 459 | Oxbow Township, deposits in ---.......-.-----...-.. 95 
deposits in....- 136-137, 167 Oxford, deposits at......- L AS SRSA osoSaeOSbe So tEec sc 226-227 
Newcastle, deposits in-....---------------.-.-------- 164 drift near 2 476 
DNewtiel dnd eposits ines = == se = =e aaa see ene 256 | Oxford County, deposits in-. 206-227, 233-234, 248-262, 318, 478 
plate showing osars in ...- 260 map Of .....+-2-2- 22-2222 222e 22 eee teers cree 490 
New Gloucester, age of deposits in .------.-.-.,.--- 393 
(OM hos seotSaastostaccensoocosns cateebases 227-228, 456 P. 
CEOS GY oceces eeesee ss Siete PEI eEh CUPS eer rentit oa Sp tise ac se shednaas bdooauesaocadocees 3, 41, 54 
New Hampshire, glacial Gerad aia TH Gecce oese2e7 ibe 210, Palermosdenositean 160-162, 167 
216, 248, 275, 356, 405, 449, 450, 476, 478 pee MUNG TOP MRSS Siduit ra ne. PARAS. M4 Un, 147 
SOW Haven, COM, mone Be oo aca re nt ye yar cel Palmyra fossilsuinie- os seensseser sae eeeer eee 172, 482 
New Tomericls, gear an sa 0 ie 2 Tenet Papoose Pond, deposits near --...-----.--.-..--- 250-252, 254 
Re ep eS es COT > 340-383 | Paris, deposits in ....----2+--.0--20-- 63, 215, 222-994, 449, 484 
Newport, deposits in ...-..- peoneaze - 139-141 OENOLS cine eae eee ieee ann ee Ne 307 
New Bortland, age of deposits in----. persosse a! 394 eee eri a eS Ee She AN ay 308 
sbi Viueyardsoietnene ill UME add acs) Wise, |evenenyarereline =! 2 i 
Roop Wane, glinereil aoadkisione ia Ppl ndoo 461 ada eatol:| Sein ROnG, Renee DaC is io sare cee ara Sica col 
i g ete Urbs) alee ee res | Parsonsfield, deposits in ..... - 256, 257, 
AMEE MTS EAI, GSH OSHS INEDE oscogsoaesacecezaase5 eb | plate showing deposits in... 332 
INicleatous Stream, deposits near ---...--.----.----.- 100 | Passadumkeag, osar in ....-..-..---- 107 
Niles, WH, ariel. eG Mn WAU TiS i RISE LRT AM AE 2a) Passadumkeag River, deposits along ------. 100 
Nevle boro; deposits ig Rae a ag aa eae NESS Passagassawawkeag Pond, deposits near... a6 143 
Nommdseyack, GUND HIS TN, Se Sei Sass onaotendaqecede 181-185 DAGEET GSBiiae ioe cra cc outer Cie eater ME 96, 99, 495 
u fossils in Ronen es er Sl aE a) art aa aaa ee 482 Peaked Mountain, eskers near...--.-.--..-.---.----- 119 
Nordenskjold, N. A. E., cited SB OCONEE SED eaasesose 269, 270 Peary sR cited ioe. 1s shel ue nate Me Ruineaer es 294, 316 
None Acton, plate showing kames near - 262 explovationalol: cece oh le eae ie eine 269 
North Auburn, age of deposits at 394 Pembroke, deposits in... 
Noni TAO ose Chui sseciaee aw Pennamaquan Lake, deposits near .....-----.--.---- 73 
A ae he 90 | Penobscot Bay, deposits near -... 92, 107, 113, 114, 133, 320, 382 
Nomi Mariaville, deposits in.. - 118-119 | plate showing osar near.....2..----+e-ceeceeee 130 
North Monmouth, erosion pear. Se ty Oe Boas SS Ms at Penobscot County, deposits in-..--..--..--.. 5 93, 
North New Portland, deposits near.......-...-- 188, 356, 474 95-104, 115-117, 119-138, 185-143, 145-147 
North Paris, deposits at.--.- po esos 2a zebeasog2eseers 442 map of p 490 
orn Senuibrent, aie OF Geipeosiis Oi aroppsasuesacsao ee Penobscot River, delta in valley of...-... 487 
INNO SISOS EEC, CFD OF GEEINISIES BU oo ucorasas eros os deposits along -..--- 103-106, 114, 117, 187, 323, 391, 400, 484 
ee Seles dele, pba Pe Wa ae he ate Fs an! deposits near West Branch of 116 
as ub Water{onds GOWNIENS HORE coesonasssasnsasocees Sa plate showing osar crossing.......--- at 106 
orth Wandlas, dejpastiie ee ees Aa ENV ES IE ae Penobscot Valley, beaches in-----..-.-.-..-........- 481 
North Woodstock, deposits at. .----..--. 219-221, 484, 439, 442 Pequawket Stream, deposits along.......---....---- 258-259 
Hee eg tacos ers arc st ace peeps arin meaner eo Perkins Plantation, deposits in--...-..-...-...--..- 171 
Norway, drift in---- = 476 TEP TARTS y aa eli cre kc eee pee ey 95 
i | WA oi iey ENGL yoceeshectebeosocasnccaseeneobcnes 95 
raised beaches m...------+-+--+s222+--2-2- 2020+ 300 PerrysNakh staid py seen te sees eee eeeee ee ye 397 
0 ery, SsandStone ane tine sesee same eee eee eee 6 
i Peru, deposits in 211-218, 381, 439 
Ohio, glacial conditigns in-.- Se 469 | Pikes Peak Range, glacial conditions in-.-...-...... 348-349 
Old Stream, deposits near ..........-... - 90-92,94 | Piscataquis County, deposits in 104-117, 
Old Stream Plains, date of deposition of. 2 393 122-126, 184-135, 171, 173 
Old Stream Valley, age of deposits in... 393 MAP Oe ees see cece eae cents sacene eee 490 
Oldtown, deposits in 124 | Piscataquis River, age of deposits along. - obbe 394 
Orient, osar near.-..- 75, 80 deposits along.-.---..-..-....-.... 63, 123-124, 135 
Orland, deposits in......-..------..... ---- 88, 92, 118, 121-122 figure showing osar near-..-..- 123 


INDEX. 497 

Page. Page. 

Pittsfield, deposits in 141, 148,427 | Sabattus, deposits at......-------------------------- 285 
EROSION BiconcsoedtosopeastissaosnatsensensscosSs5 429 | Saccarappa, deposits near......------....----------- 242 
figure showing osarin ........--.------.-------- 149 | Saco River, age of deposits along .----.------------- 394 
Pittston, deposits in.-....--...-.-..------.--------- 171 deposits along .. 252, 256-257, 258, 394, 461-462, 467, 477, 484 
Pleasant Lake, deposits near -..-.-.--..------------ 93 | Sagadahoc County, deposits in ...-..-.------ 171-174, 186-187 
Pleasant River, deposits along.... 94-95, 134-135, 227-228, 414 map of .-.....- 490 
Plymouth, kames in 145-146 | St. Albans, deposits in....-. - 148, 152 
OSH WH ssoossaescanocsssconsnosoosrs 140-142 | St. Croix Lake, deposits near. a: 80 
Poland, deposits in ..-----.-.---- 213-214, 226-227 | St. Croix River, deposits along and near... _.--- 71, 72, 73, 362 
Polaud Corner, age of deposits at... poaeoss 294 | St. George River, deposits along -..--.--..---------- 147-148, 
Porter, deposits in .....----.---.- 256, 257, 259 154-157, 361, 384, 391, 430 
plates showing deposits in...-..--.-.----..----- 448,450 | St. John River, deposits near.....---.-- Qoooosese 362, 417-418 
Portland deposits near..-....-.-.-----------.------ 215-235, | St. Lawrence River, glaciation of.-.....-.----------- 417-418 
242, 283, 323, 361, 380, 388, 434, 439, 442 | Salisbury, R. D., cited .......-.-.--.-----.----------- 266, 284 

figure showing landslip in 232 | Salmon River Valley, glacial conditions in ..--.----- 351-355 
SOREN IE ABRs Rea Mone boeracsobacooencncccsn 53-54, 286-291 TMP A -coscosonsd onsSaecsesoe Goce 352 
EEGHOU IN <s-oncgoscconsaecsasnoenco ee assoesecose 32 | Salmon Stream, deposits along .. 5 115 
Potholes, formation of --- 324-330 | Sam Ayers Stream, osar along -..-. - 115-116 
Pownal, deposits in-.---.-..---..----.---- 57, 59, 202-203, 227 | Sands, character and deposition of. - ee) 54=58) 
Precipitation during glacial time -.--..-..---------- 292 | Sangerville, deposits in ....-....-- - 126, 400 
Preglacial land surface, character of . . 265-269 | Sandy River, age of deposits along ---..------------ 394 
Prentiss, deposits in -.-.-..--..--.--- 99, 102, 126, 437-439 (le positis|al Gr py same alee ela aeeeal= e ee 484 
Presumpscot River, deposits along..---------------- 242,484 | San Miguel River Valley, deposits in-.--....-----.-- 343-344 
formation of ridge along ....--.-----.----------- 452 | Saxicava sand, occurrence of....-..-.---.--.-------- 55 
JEROTICCLy Ua he oot ceeocosoonemanooecesadoseaesoos 432 | Searboro, deposits in ...-...-.---.--------------- 233, 234, 237 
plate showing osar in ..-..----...--.-----------. 332 | Schoodic Lakes, deposits near. -.--..---------------- 88 
Schoodie (Kennebasis) River, deposits near -- Ze 91 

R. Schroeppel, N. Y., delta in.......----.-.---- on 401 

Ragged Island, beach gravel on........-....--..---- 47-48 | Scotland, raised beaches in 20 300 
Rainfall during glacial time.-..-.....-.-.-.--..----- 292 | Sea, former height of....-.-.-.---.-- -- 481-485 
Raised beaches, height of - : 481 | Sea level, determination of highest--. Stee! 482 
Raymond, osar at...----... - 236, 239 | Searsmont, deposits in. - . 147-148, 154-157, 391 
Readfield, age of deposits in. 393 | Searsport, deposits near ......-..-...--.--------+---- 137 
COPOSUS TM oo cen nme ne ee ee on nme 189-193 | Sea wall, section of..-....--.-------------------+---- A 43 
S@ctiON 1M .---- eee ee n e e en 32 | Sebago, deposits in.....-.....-.----------------- 244, 246-247 
Readyille, deposits near........----.---------------- 239 | Sebago Lake, deposits near.......-.........--+-. 63, 236-240, 
Rhone glacier, features of .-....--------------------- 297 241-243, 251, 253, 332, 484 
Richmond, deposits near .....--.---------------- 171, 173-174 plate showing osar near.....-......------------- 242 
Riggs Landing, potholes near -.--.------------------ 325-327 | Sebasticook River, deposits along... 156, 159, 168, 171-172, 481 
Ttio Grande Valley, glacial conditions in.....-...--. 343 | GHOST hjeccacecbncmconcdoresangdesescSoccousea6 429 
Rivers, character and course of glacial........-- 5-6, 317-324 | Sebec Lake, deposits near.-.---...-.---.---.-------- 135 
River terraces, character of -.---..---------- -. 61-63 | Seboois, deposits in ....-...------------- 381, 425, 434, 437-439 
origin of ......------..--+-+----+------- 67-68 | Seboois Lakes, deposits near ..-..----.-------------- 95-96 
Roach River, osar along ...- : 134 | Seboois River, age of deposits along .........-..---- 394 
Roarmg Fork, moraines along --- - 349-350 | deposits near---.--..------.---.- - 104-106, 116, 425 
tobin Hoods Cove, potholes on -. 326 | weathering in valley of.......--...--.--.-------- 267 
Rock Creek, moraines along ..----. - 350 | Sedimentation, causes of discontinuous. - -. 395-403 
Rockland, beach gravel near. -.. 48-49, 51 MALUT OO fre eee eee Seek saan fee 152118 
Caves at .-..---------------- ++ 2 eee ee eee ee eee SOSH Senzallldesweraidtbiy-esess eases sees nee eeeeee eases 116 
glacial scratches at.---...-----.----.------------ 268 | Shaler, N.S., cited.-.- 3, 4, 34, 41, 281, 455 
Rocks of Maine, kinds, condition, and mode of | Shapleiethy, Ghia tt so sscansosonsaescacccansccesaseses 459 
weathering of .....-- ..--.------------------ 6-10 | Sheepscot River, deposits along and near.......... 160, 166, 

Rocky Mountains, glacial conditions in-. 319, 338-355, 398, 405 | 168-169, 382 
Rome, deposits im -.---.------+-+0-2--20e 2s eee seen es: 184 | Shelburne, N. H., deposits in : 275, 356, 476, 478 
Royal River, deposits along......--..-...-.. 202, 214, 228, 237 | Sherman. osars in and near-....- ee Ce ae pee 974372439 
Rumford, deposits in -.-...-..--..-. 212, 218, 221-225, 435, 442 BOGE OTS ARs Oe eee eee SE EER eee, 437 
erosion near...------ 6Gh Sherman sPaultcitediesseeeeeeeeeeeeeeeee-te see eceeee 3 
Rumford Point, osar at - 248 | Shirley, deposits in..........------------------------ 125, 173 
Russell, I. C., cited 47, | Sidney, age of deposits in ....--- 393 
273, 296, 516, 317, 347, 355, 357, 397, 420, 467 | @EWOTUG 1 5 -seocesasscnaeee 182 

quoted 356-357, 445 | Silsby Plains, deposits on.........------------------ 381 
Russell Mountain, weathering on.-....-.-.-...-- 23, 266, 268 — description of ........- . 1€8-110, 114, 372, 376 
| Silverton, Colo., deposits at .....-.---..------------- 341-343 

S. | Sisladobsis Lake, deposits near - - 94-95 

Sabao Lake, deposits near-....-..-.-----------.-.---- 95 | Skowhegan, fossils in .--.----.-- ooo 482 
Sabattus, age of deposits at 393 | Smyrna, deposits in..... 77,80-81, 439 


MON XXXIV 


32 


498 INDEX. ; 


Page 
Soil-cap movement, transportation by....-.-.-.--.-- 10-11 
Solon\idepositseiny semen eee eee eee eee eects 63, 178 
OLOsioN Mears. siete esse ee etic eee eeece ee 64 
Somerset County, deposits in .-......-....-. 148-159, 171-189 
UNE) Ol 36 doetocseconanansesdcnecoacdansenacnoroDd 490 
Songo River, character of ........------------------- 251 
Soper Brook, deposits near......-.----.------------- 117 
South Acton, osar near-............c-.-.--=--------- 318 
South Albion, deposits at ...........-.-.-------- 165-167, 322 
South Bridgeton, deposits near......-..--..--------- 239 
South Lincoln, osar near ........-.-.------------ 107, 114, 400 
plate showing osar at.-..-.--.......-----.----.-- 106 


South Paris, age of deposits at-. 


deposits near..-.-...-----.-- 
South Park, glacial conditions in. . 
South TwinLake, deposits near.--....-..-...--....- 
INPENCOL TILA CLLOC a ejeee trate eee ieee eee ett 280 
Springtield, deposits near ...-. 90, 99, 102, 434, 437-439 
plate showing deposits in .-.........--..------.- 104 
SCOMON Git sconoatessoosockcncck Saousesecsrsegssos 437 
Springs, transportation of soil by-----------.------- 18-20 
Staceyville, deposits in............---...-----.----05 115 
Standish, age of deposits in 393 
depositshintera--ee-rteaseeces ee rceee ees 243-244, 484 
Stevenson, David, cited ........- 14 
Stockton, plate showing osar in. 130 
Stone, G. H., cited -...--. aoestootes 3,4 
Stratton Brook, horseback on -.......-- 188 
Streams, character of englacial ..-..-- 296-301 
character of glacial............-.....-----..--.. 291-294 
courses of subglacial ......... . 297-301, 305-310 
GiWEHO AW? coodacso=neqensseucsossslcecsescuccsos 23-24 
sedimentation by -..----- ---------+----+----0----- 15-18 
transportation by --.-~..---...------------------- 13-20 
Subglacial streams, causes of 305-308 
channels of 308-310 
direction of 297-301 


Subterranean streams, transpo-tation of soilby .-.. 18-20 


Sullivan, deposits in-.-............------------.----- 117 
Sumner, age of deposits in.-.....-....-..--..---.--- 394 


deposits in -- 213-214, 215, 381, 484 
Sunk-haze Stream, deposits along -.....-------.----- 108 
Sweden, deposits in ..-........---.-.------------ 246, 252, 300 
Switzerland, glacial lake in ..-......-..---.--.--.--- 300 

oth 
Taylor, H. R., aid by .-----.--... cosemecesescosenasss 88, 95 
Telluride, Colo., moraine near 344 
Temperature of ice-sheets .-..-- 302-304 
‘Terraces, features of.-.-.-.--.-- SAdsdascoesaeSnoSons 440-448 
Tertiary beds, absence of ....-....------------.----- 27-28 
Thomaston, gravels in .-....--------+.-------.------ 147-148 
Thorndike, age of deposits in.-------.---.------------ 393 

deposits ness. =e= ese 143, 149, 158, 435, 459 
Wal Ne haraCherO hee sees eee ee neal ae 29-30, 33-34 

composition of lower..----.------.-------------- 277-284 

composition of upper -..---..-..--.------------- 272-277 

Gis mal NOM OF peoso sods second scosersasceoseconss 31-33 

origin of ....-...- 270-272 
Tomah, deposits near 284, 320 
Tomah Stream, osars near 76-77, 83 
Topography of Maine, nature of..-.-..--...-------- 5-6 

relations of glacial rivers to ...--.-....--------- 321-323, 
Topsfield, deposits in 90-92, 94 
Torell, Q. M., cited. 269, 271 
Trescott, osar in ..--.-....- Dddaaotiddcdebeaasosontoo 79 


» 


Page. 

Troy; @OpOsits Ale een mie (oye seein ieeiae eee) ee. 141-144, 145-147 
Turner, age of deposits in 394 
deposits in..-.....--.-..----. 208 
Twentymile River, deposits along --.- 484 
Bwitchell DH aid Dy = ene eeeieeiae ieee rie 115 

Us 
Umbagog outlet, age of deposits near....-.-.....--- 394 


Uncompahgre River, glacial conditions in valley of. 344-345 
Underground streams, transportation of soilby.--. 18-20 


Uinionmideposits mea a-a- eet eases eee 384 
Union River, deltas in valley of.-... ...---. 372, 374, 391-392 

deposits along and near.-.....-.--.----- 108-110, 114, 118 
Unity, age of deposits in...-......-..-..-....-...... 393 


deltaline aoe ve cne eee ees Seer ae cate 435, 459, 469 
deposits in. -- 148, 149, 150, 158 
fossils in .....-... Soerebocaaatonccssessasasosubase 482 
Upham sWrarren: cited’. -sseceassaee eee 32, 43, 256, 284 
Upper Beddington, osar at.. 5 101 
(Ujiahybeachtoravel tines eee eee eee eee AT 
Wo 
Valley drift, character of ......-..-..-.. 58-63, 67-69, 475-489 
composition of 485-488 
definition of. - 16 
GLOSION-Of:- 1 ee eas uses eos eaten Cee et eee eee 63-67 
origin Ofes. ca Legee ties. tease nese eesee bss eet 470-475 
Vanceboro, osars in ..-....... 50 coo (MDE 7Ab 
Vassalboro, deposits in 169-170, 468 
Veazie, deposits in-.-...-... --- 124,125 
Virginia, weathering in..............-...-..---...-- 266 
Wis 
Wakefield, N. H., deposits near ........-....-.-.-- ie 256 
Waldo, age of deposits in ......-..-.-..-.-..--.----- 
deposits in'-----.------__-- 
Waldoboro, age of deposits at... 
deposits‘im=.-.----..-.---.- 162-163, 240, 269, 272-274, 283, 
290, 361, 375, 378, 382, 383-385, 387, 399, 409, 419 
plate showing moraine in ..---........-..---.--- 262 
Waldo County, deposits in..-....... 130-131, 185-139, 143-163 
TENOR sonsdoqscsssaesgsezassecee5o sondessoossese 490 
Warren, deposits in 162 
Washington, age of deposits in 393 
Washington County, deposits in ....-..--...... 70-104 
map of 490 
Waterboro, plate showing deposits in.---.-...-..... 382 
Waterford, deposits in.-...-.--....---.....-- -- 249-254 
Waterville, delta in..........- a 487 
deposits in ...-...-.---.--.-- 57, 171, 172 
figure showing deposits in .--........-.........- 379 
Wayne, deposits in ....--........-.......... 193-194, 198, 199 
GUOSHOO UN socnno core sescosesnstonsononesonsascos 13 
Weathering, examples and effects of. - 22-23, 265-269 
TASH Oi sncoesccenesoosacsborsor ccetqsenossete 8-9 
Webster, deposits in.....-...-..-.-.---..--.. 99, 186, 191, 437 
Wellington, deposits in -.............-...-..---..--- 171 
Wells, Walter, cited .............-.-..---... 3, 72, 78, 141, 292 
\W@W), OsRip soo nnconssoseeo sosssssscosousetos --- 262-263 
Wesley, deposits in ...--... Bee ostaceeees -- 88,90 
West Bowdoin, age of deposits at........-.-.-..---- 393 
plate showing deposits at --......-.-..-----.---. 186, 378 
West Branch of Penobscot River, deposits near..-. 106,116 
Westbrook, esker in--.----.-.- 235 
Westcott Stream, deposits near 138 


EE 


INDEX. 499 
Page. Page. 
West Cumberland, age of deposits at.........-..---- 393) | Winn; deposits in eee ccc een nem enen ees a= 103-104 
West Hampden, deposits near.-.-..- 130,136 | Winslow, deposits in............-.-.------..-------- 168-170 
West Lebanon, deposits in.....-...-. 263 | Winslows Mills, deposits near ..-..-. 163, 240, 272-274, 382, 399 
West Mariaville, massive near 118 plate showing moraine at - 262 
West Minot, kames near .....-...--.---------------- 214 | Wisconsin, moraines in ......---.-..---.------------ 398 
VSO, OSB Cee ne bosccoce Sosa 2eseceosbenpsaseoss 75, 82 WGEIIGMINR Tons aseoenncaossssesopSsense nase 266 
West Sumner, deposits near .-.-...-..--..---------- 213-214 | Winterport, deposits in ...............-.---.--.----- 130 
Whitefield, deposits in..-..............-.---.------- 168,169 | Winthrop, deposits in..-..-.-.....-..---.-..-------- 189, 193 
White Mountains, direction of ice flow in .--..-.--.-- 417 fossils in ......-.- 482 
LEG ISNG ETE Goes onicoosrocsaccsesaasoestonsscsaSs 10 | Wood, William, cited... 287 
Viti ens dol Dj Oni) scooceocotsnccascaeecensenessecs 292 | Woodstock, deposits in -........ 
Whitneyville, deposits in-. 90 GHUEHOM WA 5 ooagasnocHonnconds sosase sHocoonsonaDes 
Whittlesey, Charles, cited - 3 plate showing osar in 
Wilder, A. W., cited.......- 141 section across osar in 
Williamsburg, gravel near 134 | Wright, G. F., cited ............-.. 
Willimantic, gravel in..----....-----..---.---..----- 135 
WWiltonjeskers) ine ---ceces~ == =e === --- 205, 366 Ww. 
Wind, drift forms due to.....-.-----.--- -- 24-25 
transportation of soil by .---------.------------- 11-13 | Yarmouth, deposits in................--...--- 57, 203, 215, 230 
Windham, deposits in.........-..-..-..-----..-- 236-238, 484 | York County, Me., delta plains in ..-.. -- 374, 375, 387 
Windsor, age of deposits in -....-..--...--.-..------ 393 CepOSitSpManeeee see ee eee eet 255-263, 318, 478 
OPORIUS Neel eee ella . 164, 168-170 MAD Ob ssaes wg ae sence ae eae re oo ea ee ee ee 490 
plate showing deposits in ...........-----..----- 170,454 | York County, New Brunswick, deposits in......---. 70-71 


Sc 


ays a 
Serene 
Troon te § 


ADV EHRTISHMENT. 


[Monograph XXXIV.] 


The statute approved March 3, 1879, establishing the United States Geological Survey, contains 
the following provisions: 

“The publications of the Geological Survey shall consist of the annual report of operations, geo- 
logical and economic maps illustrating the resources and classification of the lands, and reports upon 
general and economic geology and paleontology. The annual report of operations of the Geological 
Survey shall accompany the annual report of the Secretary of the Interior. All special memoirs and 
reports of said Survey shall be issued in uniform quarto series if deemed necessary by the Director, but 
otherwisein ordinary octavos. Three thousand copies of each shall be published for scientific exchanges 
and for sale at the price of publication; and all literary and cartographic materials received in exchange 
shall be the property of the United States and form a part of the library of the organization: And the 
money resulting from the sale of such publications shall be covered into the Treasury of the United 
States.” 

Except in those cases in which an extra number of any special memoir or report has been sup- 
plied to the Survey by special resolution of Congress or has been ordered by the Secretary of the 
Interior, this office has no copies for gratuitous distribution. 


ANNUAL REPORTS. 


I. First Annual Report of the United States Geological Survey, by Clarence King. 1880. 8°. 79 
pp. 1map.—A preliminary report describing plan of organization and publications. 

II. Second Annual Report of the United States Geological Survey, 188081, by J. W. Powell. 
1882. 8°. lv, 588 pp. 62pl. 1 map. 

Ill. Third Annual Report of the United States Geological Survey, 1881~82, by J. W. Powell. 
1883. 8°. xvili,564 pp. 67 pl. and maps. 

IV. Fourth Annual Report of the United States Geological Survey, 1882~’83, by J. W. Powell. 
1884. 8°. xxxii,473 pp. 85 pl. and maps. 

VY. Fifth Annual Report of the United States Geological Survey, 1883-’84, by J. W. Powell. 
1885. 8°. xxxvi,469 pp. 58 pl. and maps. 

VI. Sixth Annual Report of the United States Geological Survey, 1884~85, by J. W. Powell. 
1885. 8°. xxix, 570 pp. 65 pl. and maps. 

VII. Seventh Annual Report of the United States Geological Survey, 1885~86, by J. W_ ! owell. 
1888. 8°. xx,656pp. 71 pl. and maps. 

VIII. Eighth Annual Report of the United States Geological Survey, 1886~87, by J. W. Powell. 
1889. 8°. 2pt. xix, 474, xii pp., 53 pl. and maps; 1 prel. leaf, 475-1063 pp., 54-76 pl. and maps. 

TX. Ninth Annual Report of the United States Geological Survey, 1887~88, by J. W. Powell. 
1889. 8°. xili,717 pp. 88 pl. and maps. 

X. Tenth Annual Report of the United States Geological Survey, 1888~89, by J. W. Powell. 
1890. 8°. 2pt. xv, 774 pp., 98 pl. and maps; viii, 123 pp. 

XI. Eleventh Annual Report of the United States Geological Survey, 1889-90, by J. W. Powell. 
1891. 8°. 2pt. xv, 757 pp., 66 pl. and maps; ix, 351 pp., 30 pl. and maps. 

XII. Twelfth Annual Report of the United States Geological Survey, 189091, by J. W. Powell. 
1891. 8°. 2 pt., xili, 675 pp., 53 pl.and maps; xviii, 576 pp., 146 pl. and maps. 

XIII. Thirteenth Annual Report of the United States Geological Survey, 1891~92, by J. W. 
Powell. 1893. 8°. 3 pt. vii, 240 pp., 2 maps; x, 372 pp., 105 pl. and maps; xi, 486 pp., 77 pl. and 
maps. 

: XIV. Fourteenth Annual Report of the United States Geological Survey, 189293, by J. W. 
Powell. 1893. 8°. 2pt. vi, 321 pp., 1 pl.; xx, 597 pp., 74 pl. and maps. 

XY. Fifteenth Annual Report of the United States Geological Survey, 1893-91, hy J. W. Powell. 
1895. 8°. xiv, 755 pp., 48 pl. and maps. 

XVI. Sixteenth Annual Report of the United States Geological Survey, 1894-95, Charles D. 
Walcott, Director. 1895. (Part I, 1896.) 8°. 4 pt. xxii, 910 pp., 117 pl. and maps; xix, 598 pp.. 43 
pl. and maps; xv, 646 pp., 23 pl.; xix, 735 pp., 6 pl. 

XVII. Seventeenth Annual Report of the United States Geological Survey, 1895~96, Charles 
D. Walcott, Director. 1896. 8°. 3 pt.in4 vol. xxii, 1076 pp., 67 pl. and maps; xxv, 864 pp., 113 pl. 
and maps; xxiii, 542 pp., 8 pl. and maps; iii, 543-1058 pp., 9-13 pl. 

XVIII. Highteenth Annual Report of the United States Geological Survey, 1896-97, Charles D. 
Walcott, Director. 1897. (Parts II and III, 1898.) 8°. 5pt.inGyol. 1-440 pp.,4 pl. and maps; i-y, 


I 


II ADVERTISEMENT. 


1-653 pp., 105 pl. and maps; i-v, 1-861 pp., 118 pl. and maps; i-x, 1-756 pp., 102 pl. and maps; i-xii 
1-642 pp., 1 pl.; 643-1400 pp.” ; Bee Dae ele 

XIX. Nineteenth Annual Report of the United States Geological Survey, 1897-98, Charles D. 
Walcott, Director. 1898. 8°. 6 pt. in 7 vol. 


MONOGRAPHS. 


I. Lake Bonneville, by Grove Karl Gilbert. 1890. 4°. xx,438 pp. S5lpl. 1lmap. Price $1.50. 

II. Tertiary History of the Grand Canon District, with Atlas by Clarence E. Dutton, Capt., U.S. A. 
1882. 4°. xiv, 264 pp. 42 pl. and atlas of 24 sheets folio. Price $10.00. 

III. Geology of the Comstock Lode and the Washoe District, with Atlas, by George F. Becker. 
1882. 4°. xy, 422 pp. Tpl. and atlas of 21 sheets folio. Price $11.00. 

IV. Comstock Mining and Miners, by Eliot Lord. 1883. 4°. xiv, 451 pp. 3pl. Price $1.50. 

V. The Copper-Bearing Rocks of Lake Superior, by Roland Duer Irving. 1883. 4°. xvi, 464 
pp. 151. 29pl. and maps. Price $1.85. 

VI. Contributions to the Knowledge of the Older Mesozoic Flora of Virginia, by William Morris 
Fontaine. 1883. 4°. xi, 144 pp. 541. 54 pl. Price $1.05. 

VII. Silver-Lead Deposits of Eureka, Nevada, by Joseph Story Curtis. 1884. 4°. xiii, 200 pp. 
16 pl. Price $1.20. 

VIII. Paleontology of the Eureka District, by Charles Doolittle Walcott. 1884. 4°. xili, 298 
pp. 241. 24 pl. Price $1.10. , 

IX. Brachiopoda and Lamellibranchiata of the Raritan Clays and Greensand Marls of New 
Jersey, by Robert P. Whitfield. 1885. 4°. xx,338pp. 35 pl. 1map. Price $1.15. 

X. Dinocerata. A Monograph of an Extinct Order of Gigantic Mammals, by Othniel Charles 
Marsh. 1886. 4°. xviii, 243 pp. 561. 56 pl. Price $2.70. 

XI. Geological History of Lake Lahontan, a Quaternary Lake of Northwestern Nevada, by 
Israel Cook Russell. 1885. 4°. xiv, 288 pp. 46 pl. and maps. Price $1.75. 

XII. Geology and Mining Industry of Leadville, Colorado, with Atlas, by Samuel Franklin 
Emmons. 1886. 4°. xxix, 770 pp. 45 pl. and atlas of 35 sheets folio. Price $8.40. ; 

XIII. Geology of the Quicksilver Deposits of the Pacific Slope, with Atlas, by George F. Becker. 
1888. 4°. xix, 486 pp. 7 pl. and atlas of 14 sheets folio. Price $2.00. 

XIV. Fossil Fishes and Fossil Plants of the Triassic Rocks of New Jersey and the Connecticut 
Valley, by John S. Newberry. 1888. 4°. xiv, 152pp. 26pl. Price $1.00. 

XV. The Potomac or Younger Mesozoic Flora, by William Morris Fontaine. 1889. 4°. xiv, 
377 pp. 180 pl. Text and plates bound separately. Price $2.50. 

XVI. The Paleozoic Fishes of North America, by John Strong Newberry. 1889. 4°. 340 pp. 
53 pl. Price $1.00. 

XVII. The Flora of the Dakota Group, a Posthumous Work, by Leo Lesquereux. Edited by 
F, H. Knowlton. 1891. 4°. 400 pp. 66pl. Price $1.10. 

XVIII. Gasteropoda and Cephalopoda of the Raritan Clays and Greensand Marls of New Jersey, 
by Robert P. Whitfield. 1891. 4°. 402pp. 50pl. Price $1.00. 

XIX. The Penokee Iron-Bearing Series of Northern Wisconsin and Michigan, by Roland D. 
Trying and C. R. Van Hise. 1892. 4°. xix, 534 pp. Price $1.70. 

XX. Geology of the Eureka District, Nevada, with an Atlas, by Arnold Hague. 1892. 4°. xvii, 
419 pp. 8pl. Price $5.25. 

XXI. The Tertiary Rhynchophorous Coleoptera of the United States, by Samuel Hubbard Seud- 
der. 1893. 4°. xi, 206pp. 12pl. Price 90 cents. 

XXII. A Manual of Topographic Methods, by Henry Gannett, Chief Topographer. 1893. 4°, 
xiv, 300 pp. 18 pl. Price $1.00. 

XXII. Geology of the Green Mountains in Massachusetts, by Raphael Pumpelly, T. Nelson Dale, 
and J. E. Wolff. 1894. 4°. xiv, 206pp. 23 pl. Price $1.30. 

XXIV. Mollusca and Crustacea of the Miocene Formations of New Jersey, by Robert Parr Whit- 
field. 1894. 4°. 193 pp. 24 pl. Price 90 cents. 

XXV. The Glacial Lake Agassiz, by Warren Upham. 1895, 4°. xxiv, 658 pp. 38pl. Price $1.70. 

XXVI. Flora of the Amboy Clays, by John Strong Newberry; a Pusthumous Work, edited by 
Arthur Hollick. 1895. 4°. 260 pp. 58pl. Price $1.00. 

XXVII. Geology of the Denver Basin in Colorado, by Samuel Franklin Emmons, Whitman Cross, 
and George Homans Eldridge. 1896. 4°. 556pp. 31pl. Price $1.50. 

XXVIII. The Marquette Iron-Bearing District of Michigan, with Atlas, by C. R. Van Hise and 
W. S. Bayley, including a Chapter on the Republic Trough, by H, L. Smyth. 1895. 4°. 608 pp. 35 
pl. and atlas of 39 sheets folio. Price $5.75. 

XXIX. Geology of Old Hampshire County, Massachusetts, comprising Franklin, Hampshire, and 
Hampden Counties, by Benjamin Kendall Emerson. 1898. 4°. xxi, 790 pp. 35pl._ Price $1.90. 

XXX. Fossil Medusx, by Charles Doolittle Walcott. 1898. 4°. ix,201pp. 47pl. Price $1.50. 

XXXI. Geology of the Aspen Mining District, Colorado, with Atlas, by Josiah Edward Spurr. 

1898. 4°. xxxy, 260 pp. 43 pl. and atlas of 30 sheets folio. Price $3.60. 

XXXII. Geology of the Yellowstone National Park, Part II, Descriptive Geology, Petrography, 
and Paleontology. by Arnold Hague, J. P. Iddings, W. Harvey Weed, Charles D. Walcott, G. H. Girty, 
T. W. Stanton, and F. H. Knowlton. 1899. 4°. xvii, 893 pp. 121 pl. Price——. 

XXXIII. Geology of the Narragansett Basin, by N. S. Shaler, J. B. Woodworth, and August F. 
Foerste. 1899. 4°. xx, 402 pp. 3lpl. Price 3 


ADVERTISEMENT. III 


XXXIV. The Glacial Gravels of Maine and their Associated Deposits, by George H. Stone. 1899. 
xili, 499 pp. 52 pl. Price : 

XXXV. The Later Extinet Floras of North America, by John Strong Newberry; edited by 
Arthur Hollick. 1898. 4°. xviii, 295 pp. 68 pl. Price $1.25. 
In preparation: 

XXXVI. The Crystal Falls Iron-Bearing District of Michigan, by J. Morgan Clements and 
Henry Lloyd Smyth; with a Chapter on the Sturgeon River Tongue, by William Shirley Bayley. 

XXXVII. Flora of the Lower Coal Measures of Missouri, by David White. 

XXXVIII. The Illinois Glacial Lobe, by Frank Leverett. 

—Flora of the Laramie and Allied Formations, by Frank Hall Knowlton. 


BULLETINS. 


1. On Hypersthene-Andesite and on Triclinie Pyroxene in Augitic Rocks, by Whitman Cross. 
with a Geological Sketch of Buffalo Peaks, Colorado, by S. F. Emmons. 1883. 8°. 42 pp. 2 pl, 
Price 10 cents. 

2. Gold and Silver Conversion Tables, giving the Coining Values of Troy Ounces of Fine Metal, 
etc., computed by Albert Williams, jr. 1883. 8°. 8pp. Price 5 cents. 

3. On the Fossil Faunas of the Upper Devonian, along the Meridian of 76° 30’, from Tompkins 
County, N. Y., to Bradford County, Pa., by Henry 8. Williams. 1884. 8°. 36 pp. Price 5 cents, 

4, On Mesozoic Fossils, by Charles A. White. 1884. 8°. 36pp. 9pl. Price 5 cents. 

5. A Dictionary of Altitudes in the United States, compiled by Henry Gannett. 1884. 8°. 325 
pp. Price 20 cents. : 

6. Elevations in the Dominion of Canada, by J. W.Spencer. 1884. 8°. 43 pp. Price 5 cents. 

7. Mapoteca Geologica Americana, A Catalogue of Geological Maps of America (North and 
South), 1752-1881, in Geographic and Chronologic Order, by Jules Marcou and John Belknap Marcou. 
1884. 8°. 184 pp. Price 10 cents. 

8. On Secondary Enlargements of Mineral Fragments in Certain Rocks, by R. D. Irving and 
C. R. Van Hise. 1884. 8°. 56pp. Gpl. Price 10 cents. 

9. A Report of Work done in the Washington Laboratory during the Fiscal Year 1883~84. EF. W. 
Clarke, Chief Chemist; T. M. Chatard, Assistant Chemist. 1884. 8°. 40pp. Price 5 cents. 

10. On the Cambrian Faunas of North America. Preliminary Studies, by Charles Doolittle 
Walcott. 1884. 8°. 74pp. 10pl. Price 5 cents. 

11. On the Quaternary and Recent Mollusca of the Great Basin; with Description of New 
Forms, by R. Ellsworth Call. Introduced by a Sketch of the Quaternary Lakes of the Great Basin, 
by G.K. Gilbert. 1884. 8°. 66pp. 6pl. Price 5 cents. 

12. A Crystallographic Study of the Thinolite of Lake Lahontan, by Edward S. Dana. 1884. 8°. 
34 pp. 3pl. Price 5 cents. 

13. Boundaries of the United States and of the Several States and Territories, with a Historical 
Sketch of the Territorial Changes, by Henry Gannett. 1885. 8°. 135 pp. Price 10 cents. 

14. The Electrical and Magnetic Properties of the Iron-Carburets, by Carl Barus and Vincent 
Strouhal. 1885. 8°. 238 pp. Price 15 cents. ; 

: 15. On the Mesozoic and Cenozoic Paleontology of California, by Charles A. White. 1885. 8°. 
33 pp. Price 5 cents. 

; 16. On the Higher Devonian Faunas of Ontario County, New York, by John M. Clarke. 1885. 8°. 

86 pp. 3pl. Priced cents. 

17. On the Development of Crystallization in the Igneous Rocks of Washoe, Nevada, with Notes 
on the Geology of the District, by Arnold Hague and Joseph P. Iddings. 1885. 8°. 44 pp. Price5 
cents. 

18. On Marine Eocene, Fresh-Water Miocene, and other Fossil Mollusca of Western North 
America, by Charles A. White. 1885. 8°. 26pp. 3pl. Price 5 cents. 

19. Notes on the Stratigraphy of California, by George F. Becker. 1885. 8°. 28pp. Priced cents. 

20. Contributions to the Mineralogy of the Rocky Mountains, by Whitman Cross and W. F. Hille- 
brand. 1885. 8°. 114 pp. 1pl. Price 10 cents. ‘ 

21. The Lignites of the Great Sioux Reservation; a Report on the Region between the Grand 
and Moreau Rivers, Dakota, by Bailey Willis. 1885. 8°. 16pp. 5 pl. Price 5 cents. 

22. On New Cretaceous Fossils from California, by Charles A. White. 1885. 8°. 25 pp. 5pl. 
Price 5 cents. ih 

23. Observations on the Junction between the Eastern Sandstone and the Keweenaw Series on 
Keweenaw Point, Lake Superior, by R. D. Irving and T. C. Chamberlin. 1885. 8°. 124 pp. 17 pl. 
Price 15 cents. 

24, List of Marine Mollusca, comprising the Quaternary Fossils and Recent Forms from American 
Localities between Cape Hatteras and Cape Roque, including the Bermudas, by William Healey Dall. 
1885. 8°. 336 pp. Price 25 cents. 

25. The Present Technical Condition of the Steel Industry of the United States, by Phineas 
Barnes. 1885. 8°. 85 pp. Price 10 cents. 

26. Copper Smelting, by Henry M. Howe. 1885. 8°. 107 pp. Price 10 cents. 

27. Report of Work done in the Division of Chemistry and Physics, mainly during the Fiscal Year 
1884-85. 1886. 8°. 80/pp. Price 10 cents. 

28. The Gabbros and Associated Hornblende Rocks occurring in the Neighborhood of Baltimore, 
Maryland, by George Huntington Williams. 1886. 8°. 78pp. 4£pl. Price 10 cents. 


IV ADVERTISEMENT. 


29. On the Fresh-Water Invertebrates of the North American Jurassic, by Charles A. White. 1886. 
8°. 41 pp. 4pl. Price 5 cents. 

30. Second Contribution to the Studies on the Cambrian Faunas of North America, by Charles 
Doolittle Walcott. 1886. 8°. 369pp. 33pl. Price 25 cents. 

31. Systematic Review of our Present Knowledge of Fossil Insects, including Myriapods and 
Avrachnids, by Samuel Hubbard Scudder. 1886. 8°. 128 pp. Price 15 cents. 

32. Lists and Analyses of the Mineral Springs of the United States; a Preliminary Study, by 
Albert C. Peale. 1886. 8°. 235 pp. Price 20 cents. 

33. Notes on the Geology of Northern California, by J.S. Diller. 1886. 8°. 23 pp. Price5 cents. 

34. On the Relation ofthe Laramie Molluscan Fauna to that of the Succeeding Fresh-Water Eocene 
and Other Groups, by Charles A. White. 1886. 8°. 54 pp. 5pl. Price 10 cents. 

35. Physical Properties of the Iron-Carburets, by Carl Barus and Vincent Strouhal. 1886. 8°. 
62 pp. Price 10 cents. 

36. Subsidence of Fine Solid Particlesin Liquids, by Carl Barus. 1886. 8°. 58pp. Price 10cents. 

37. Types of the Laramie Flora, by Lester F. Ward. 1887. 8°. 354pp. 57 pl. Price 25 cents. 

38. Peridotite of Elliott County, Kentucky, byJ.S. Diller. 1887. 8°. 31pp. 1pl. Price5cents. 

39. The Upper Beaches and Deltas of the Glacial Lake Agassiz, by Warren Upham. 1887. 89. 
84 pp. pl. Price 10 cents. 

40. Changes in River Courses in Washington Territory due to Glaciation, by Bailey Willis. 1887. 
8°. 10pp. 4 pl. Price 5 cents. 

41. On the Fossi” faunas of the Upper Devonian—the Genesee Section, New York, by Henry 8S. 
Williams. 1887. 8°. 121pp. 4pl. Price 15 cents. 

42. Reportof Work done in the Division of Chemistry and Physics, mainly during the Fiscal Year 
188586. F. W. Clarke, Chief Chemist. 1887. 8°. 152pp. 1pl. Price 15 cents. 

43. Tertiary and Cretaceous Strata of the Tuscaloosa, Tombighee, and Alabama Rivers, by Eugene 
A. Smith and Lawrence C. Johnson. 1887. 8°. 189 pp. 21pl. Price 15 cents. 

44. Bibliography of North American Geology for 1886, by Nelson H. Darton. 1887. 8°. 35 pp. 
Price 5 cents. 

45. The Present Condition of Knowledge of the Geology of Texas, by Robert T. Hill. 1887. 8°. 
94 pp. Price 10 cents. 

46. Nature and Origin of Deposits of Phosphate of Lime, by R. A. F. Penrose, jr., with an Intro- 
duction by N.S. Shaler. 1888. 8°. 143 pp. Price 15 cents. 

47. Analyses of Waters of the Yellowstone National Park, with an Account of the Methods of 
Analysis employed, by Frank Austin Gooch and James Edward Whitfield. 1888. 8°. 84pp. Price 
10 cents. 

48. On the Form and Position of the Sea Level, by Robert Simpson Woodward. 1888. 8°. 88 
pp. Price 10 cents. . 

. 49. Latitudes and Longitudes of Certain Points in Missouri, Kansas, and New Mexico, by Robert 
Simpson Woodward. 1889. 8°. 133 pp. Price 15 cents. 

50. Formulas and Tables to Facilitate the Construction and Use of Maps, by Robert Simpson 
Woodward. 1889. 8°. 124 pp. Price 15 cents. 

51. On Invertebrate Fossils from the Pacific Coast, by Charles Abiathar White. 1889. 8°. 102 
pp. 14pl. Price 15 cents. 

52. Subaérial Decay of Rocks and Origin of the Red Color of Certain Formations, by Israel 
Cook Russell. 1889. 8°. 65pp. 5pl. Price 10 cents. 

53. The Geology of Nantucket, by Nathaniel Southgate Shaler. 1889. 8°. 55 pp. 10pl. Price 
10 cents. 

54, On the Thermo-Electric Measurement of High Temperatures, by Carl Barus. 1889. 8°. 
313 pp.,inel.1 pl. 11pl. Price 25 cents. 

55. Report of Work done in the Division of Chemistry and Physics, mainly during the Fiscal 
Year 1886~87. Frank Wigglesworth Clarke, Chief Chemist. 1889. 8°. 96 pp. Price 10 cents. 

56. Fossil Wood and Lignite of the Potomac Formation, by Frank Hall Knowlton. 1889. 8°. 
72pp. Tpl. Price 10 cents. 

57. A Geological Reconnoissance in Southwestern Kansas, by Robert Hay. 1890. 8°. 49 pp. 
2pl. Price 5 cents. 

58. The Glacial Boundary in Western Pennsylvania, Ohio, Kentucky, Indiana, and Illinois, by 
George Frederick Wright, with an Introduction by Thomas Chrowder Chamberlin. 1890. 8°. 112 
pp.,inel.l pl. 8pl. Price 15 cents. 

59. The Gabbros and Associated Rocks in Delaware, by Frederick D. Chester. 1890. 8°. 45 
pp. ipl. Price 10 cents. ; 

60. Report of Work done in the Division of Chemistry and Physics, mainly during the Fiscal 
Year 188788. F. W. Clarke, Chief Chemist. 1890. 8°. 174 pp. Price 15 cents. 

61. Contributions to the Mineralogy of the Pacific Coast, by William Harlow Melville and Wal- 
demar Lindgren. 1890. 8°. 40 pp. 3pl. Price 5 cents. 

62. The Greenstone Schist Areas of the Menominee and Marquette Regions of Michigan, a Con- 
tribution to the Subject of Dynamic Metamorphism in Eruptive Rocks, by George Huntington Williams, 
with an Introduction by Roland Duer Irving. 1890. 8°. 241 pp. 16 pl. Price 30 cents. 

; 63. A Bibliography of Paleozoic Crustacea from 1698 to 1889, including a List of North-Amer- 
ican Species and a Systematic Arrangement of Genera, by Anthony W. Vogdes. 1890. 8°. 177 pp. 
Price 15 cents. 

64. A Report of Work done in the Division of Chemistry and Physics, mainly during the Fiscal 

Year 1888~89. F. W. Clarke, Chief Chemist. 1890. 8°. 60 pp. Price 10 cents. 


ADVERTISEMENT. = VW 


65. Stratigraphy of the Bituminous Coal Field of Pennsylvania, Ohio, and West Virginia, by 
Israel C. White. 1891. 8°. 212 pp. i11pl. Price 20 cents. 

66. On a Group of Voleanic Rocks from the Tewan Mountains, New Mexico, and on the Occur- 
rence of Primary Quartz in Certain Basalts, by Joseph Paxson Iddings. 1890. 8°. 34 pp. Price5 
cents. 

67. The Relations of the Traps of the Newark System in the New Jersey Region, by Nelson 
Horatio Darton. 1890. 8°. 82pp. Price 10 cents. 

68. Earthquakes in California in 1889, by James Edward Keeler. 1890. 8°. 25 pp. Price 5 
cents. 

69. A Classed and Annotated Biography of Fossil Insects, by Samuel Howard Scudder. 1890. 
8°. 101 pp. Price 15 cents. 

70. A Report on Astronomical Work of 1889 and 1890, by Robert Simpson Woodward. 1890. 8°. 
79 pp. Price 10 cents. 

71. Index to the Known Fossil Insects of the World, including Myriapods and Arachnids, by 
Samuel Hubbard Scudder. 1891. 8°. 744 pp. Price 50 cents. 

72. Altitudes between Lake Superior and the Rocky Mountains, by Warren Upham. 1891. 8°. 
229 pp. Price 20 cents. 

73. The Viscosity of Solids, by Carl Barus. 1891. 8°. xii, 189 pp. 6pl. Price 15 cents. 

74. The Minerals of North Carolina, by Frederick Augustus Genth. 1891. 8°. 119pp. Price 
15 cents. 

75. Record of North American Geology for 1887 to 1889, inclusive, by Nelson Horatio Darton. 
1891. 8°. 173 pp. Price 15 cents. 

76. A Dictionary of Altitudes in the United States (Second Edition), compiled by Henry Gannett, 
'Chief Topographer. 1891. 8°. 393 pp. Price 25 cents. 

77. The Texan Permian and its Mesozoic Types of Fossils, by Charles A. White. 1891. 8°. 51 
ipp. 4 pl. Price 10 cents. 

78. A Report of Work done in the Division of Chemistry and Physics, mainly during the Fiscal 
Year 1889-90. F. W. Clarke, Chief Chemist. 1891. 8°. 131 pp. Price 15 cents. 

. 79. A Late Volcanic Eruption in Northern California and its Peculiar Lava, by J. S. Diller. 

80. Correlation Papers—Devonian and Carboniferous, by Henry Shaler Williams. 1891. 8°. 
279 pp. Price 20 cents. 

81. Correlation Papers—Cambrian, by Charles Doolittle Walcott. 1891. 8°. 547 pp. 3 pl. 
Price 25 cents. 

82. Correlation Papers—Cretaceous, by Charles A. White. 1891. 8°. 273 pp. 3pl. Price 20 
cents. 

83. Correlation Papers—Hocene, by William Bullock Clark. 1891. 8°. 173 pp. 2pl. Price 
15 cents. 

84. Correlation Papers—Neocene, by W. H. Dall and G. D. Harris. 1892. 8°. 349 pp. 3 pl. 
Price 25 cents. 

85. Correlation Papers—The Newark System, by Israel Cook Russell. 1892. 8°. 344 pp. 13 pl. 
Price 25 cents. 

86. Correlation Papers—Archean and Algonkian, by C.R. Van Hise. 1892. 8°. 549 pp. 12 pl. 
Price 25 cents. 

87. A Synopsis of American Fossil. Brachiopoda, including Bibliography and Synonymy, by . 
Charles Schuchert. 1897. 8°. 464 pp. Price 30 cents. 

88. The Cretaceous Foraminifera of New Jersey, by Rufus Mather Bagg, Jr. 1898. 8°. 89 pp. 
6 pl. Price 10 cents. 

89. Some Lava Flows of the Western Slope of the Sierra Nevada, California, by F. Leslie 
Ransome. 1898. 8°. 74 pp. 11pl. Price 15 cents. 

90, A Report of Work done in the Division of Chemistry and Physics, mainly during the Fiscal 
Year 1890-91. F. W. Clarke, Chief Chemist. 1892. 8°. 77 pp. Price 10 cents. 

91. Record of North American Geology for 1890, by Nelson Horatio Darton. 1891. 8°. 88 pp. 
Price 10 cents. 

92. The Compressibility of Liquids, by Carl Barus. 1892. 8°. 96 pp. 29 pl. Price 10 cents. 

93. Some Insects of Special Interest from Florissant, Colorado, and Other Points in the Tertiaries 
of Colorado and Utah, by Samuel Hubbard Scudder. 1892. 8°. 35 pp. 3pl. Priced cents. 

94. The Mechanism of Solid Viscosity, by Carl Barus. 1892. 8°. 138 pp. Price 15 cents. 

95. Earthquakes in California in 1890 and 1891, by Edward Singleton Holden. 1892. 8°. 31 pp. 
Price 5 cents. 

96. The Volume Thermodynamics of Liquids, by Carl Barus. 1892. 8°. 100pp. Price 10 cents. 

97. The Mesozoic Echinodermata of the United States, by W.B. Clark. 1893. 8°. 207 pp. 50pl. 
Price 20 cents. ‘ 

98. Flora of the Outlying Carboniferous Basins of Southwestern Missouri, by David White. 
1893. 8. 139 pp. dpl. Price 15 cents. 

99. Record of North American Geology for 1891, by Nelson Horatio Darton. 1892. 8°. 73 pp. 
Price 10 cents. 

100. Bibliography and Index of the Publications of the U. 8. Geological Survey, 1879-1892, by 
Philip Creyeling Warman. 1893. 8°. 495 pp. Price 25 cents. 

101. Insect Fauna of the Rhode Island Coal Field, by Samuel Hubbard Sendder. 1893. 8°. 
27pp. 2pl. Price 5 cents. 

102. A Catalogue and Bibliography of North American Mesozoic Invertebrata, by Cornelius 
Breckinridge Boyle. 1892. 8°. 315 pp. Price 25 cents. 


VI - ADVERTISEMENT. 


103. High Temperature Work in Igneous Fusion and Ebullition, chiefly in Relation to Pressure, 
by Carl Barus, 1893. 8°. 57 pp. 9pl. Price 10 cents. 
104. Glaciation of the Yellowstone Valley north of the Park, by Walter Harvey Weed. 1893. 8°. 
4ipp. 4pl. Price 5 cents. 
105. The Laramie and the Oyerlying Livingstone Formation in aoa by Walter Harvey 
Weed, with Report on Flora, by Frank Hall Knowlton. 1893. 8°. 68 pp. 6pl. Price 10 cents. 
106. The Colorado Formation and its Invertebrate Fauna, by T. AW. Stanton. 1893. 8°. 288 
pp. 45 pl. Price 20 cents. 
107. The Trap Dikes of the Lake Champlain Region, by James Furman Kemp and Vernon 
Freeman Marsters. 1893. 8°. 62pp. 4 pl. Price 10 cents. 
108. A Geological Reconnoissance in Central Washington, hy Israel Cook Russell. 1893. 8°. . 
108-pp. 12 pl. Price.15 cents. 
109. The Eruptive and Sedimentary Rocks on Pigeon Point, Minnesota, and their Contact Phe- 
nomena, by William Shirley Bayley. 1893. 8°. 121 pp. 16pl. Price 15 cents. 
110. The Paleozoic Section in the Vicinity of Three Forks, Montana, by Albert Charles Peale, 
893. 8°. 56pp. 6 pl. Price 10 cents. 
111. Geology of the Big Stone Gap Coal Fields of Virginia and Kentucky, by Marius R. Camp- 
bell, 1893. 8°. 106pp. 6 ‘pl Price 15 cents. 
112. Earthquakes in California in 1892, by Charles D, Perrine. 1893. 8°. 57 pp. Price 10 cents. 
113. A Report of Work done in the Division of Chemistry during the Fiscal Years 1891-92 and 
1892-93. KF. W. Clarke, Chief Chemist. 1893. 8°. 115 pp. Price 15 cents. 
114. Earthquakes in California in 1893, by Charles D. Perrine. 1894. 8°. 23 pp. Price 5 cents. 
115. A Geographic Dictionary of Rhode Island, by Henry Gannett. 1894. 8°. 31pp. Price 
5 cents. 
116. A Geographic Dictionary of Massachusetts, by Henry Gannett. 1894. 8°. 126 pp. Price 
15 cents. 
117. A Geographie Dictionary of Connecticut, by Henry Gannett. 1894. 8°. 67 pp. Price 10 
cents. 
118. A Geographic Dictionary of New Jersey, by Henry Gannett. 1894. 8°. 131 pp. Price 15 
cents, 
119. A Geological Reconnoissance in Northwest Wyoming, by George Homans Eldridge. 1894. 
8°. 72 pp. Price 10 cents. 
120. The Devonian System of Hastern Pennyslvania and New York, by Charles 8. Prosser. 1894. 
-8°, 8lpp. 2pl. Price 10 cents. 
121. A Bibliography of North American Paleontology, by Charles Rollin Keyes. 1894. 8°. 251 
pp. Price 20 cents. 
122. Results of Primary Triangulation, by Henry Gannett, 1894. 8°. 412 pp. 17 pl. Price 
25 cents. 
123. A Dictionary of Geographic Positions, by Henry Gannett. 1895. 8°. 183 pp. lpl. Price 
15 cents. 
124, Revision of North American Fossil Cockroaches, by Samuel Hubbard Seudder. 1895. 8°. 
176 pp. 12 pl. Price 15 cents. 
125. The Constitution of the Silicates, by Frank Wigglesworth Clarke. 1895. 8°. 109 pp. 
Price 15 cents, 
126. A Mineralogical Lexicon of Franklin, Hampshire, and Hampden counties, Massachusetts, 
by Benjamin Kendall Emerson. 1895. 8°. 180 pp. 1pl. Price 15 cents. 
127. Catalogue and Index of Contributions to North American Geology, 1732-1891, by Nelson 
Horatio Darton. 1896, 8°. 1045 pp. Price 60 cents. 
128. The Bear River Formation and its Characteristic Fauna, by Charles A. White. 1895, 8°. 
108 pp. 11pl. Price 15 cents. 
129. Earthquakes in California in 1894, by Charles D. Perrine. 1895. 8°. 25pp. Price 5 cents. 
130. Bibliography and Index of North American Geology, Paleontology, Petrology, and Miner- 
alogy for 1892 and 1893, by Fred Boughton Weeks. 1896. 8°. 210 pp. Price 20 cents. 
131. Report of Progress of the Division of Hydrography for the Calendar Years 1893 and 1894, 
by Frederick Haynes Newell, Topographer in Charge. 1895. 8°. 126 pp. Price 15 cents. 
132. The Disseminated Lead Ores of Southeastern Missouri, by Arthur Winslow. 1896. 8°. 
3lpp. Price 5 cents. : 
133. Contributions to the Cretaceous Paleontology of the Pacific. Coast: The Fauna of the 
Knoxville Beds, by T. W. Stanton. 1895. 8°. 132pp. 20pl. Price 15 cents. 
134. The Cambrian Rocks of Pennsylvania, by Charles Doolittle Walcott. 1896. 8°. 43 pp. 
15 pl. Price 5 cents. 
135. Bibliography and Index of North American Geology, Paleontology, Petrology, and Miner- 
alogy for the Year 1894, by F. B. Weeks. 1896. 8°. 141 pp. Price 15 cents. 
136. Voleanic mGciee of South Mountain, Pennsylvania, by Florence Bascom. 1896. 8°. 124 pp. 
28 pl. Price 15 cents. 
137. The Geology of the Fort Riley Military Reservation and Vicinity, Kansas, by Robert Hay. 
1896. 8°. 35pp. 8pl. Price 5 cents. 
138. Artesian-Well Prospects in the Atlantic Coastal Plain Region, by N. H. Darton. 1896. 8°. 
228 pp. 19 pl. Price 20 cents. 
139. Geology of the Castle Mountain Mining District, Montana, by W. H. Weed and L. VY. Pirs- 
son. 1896. 8°. 164pp. 17pl. Price 15 cents. 
140. Report of Progress of the Division of Hydrography for the Calendar Year 1895, by Frederick 
Haynes Newell, Hydrographer i in Charge. 1896. 8°. 356 pp. Price 25 cents. 


1 


ADVERTISEMENT. VII 


141. The Eocene Deposits of the Middle Atlantic Slope in Delaware, Maryland, and Virginia, 
by William Bullock Clark. 1896. 8°. 167 pp. 40pl. Price 15 cents. 

142. A Brief Contribution to the Geology and Paleontology of Northwestern Louisiana, by 
T. Wayland Vaughan. 1896. 8°. 65 pp. 4 pl. Price 10 cents. 

143, A Bibliography of Clays and the Ceramic Arts, by John C. Branner. 1896. 8°. 114 pp. 
Price 15 cents. 

144. The Moraines of the Missouri Coteau and their Attendant Deposits, by James Edward Todd. 
1896. 8°. T1pp. 21pl. Price 10 cents. 

145. The Potomac Formation in Virginia, by W. M. Fontaine. 1896. 8°. 149pp. 2pl. Price 
15 cents. 

146. Bibliography and Index of North American Geology, Paleontology, Petrology, and Miner- 
alogy for the Year 1895, by F. B. Weeks. 1896. 8°. 130 pp. Price 15 cents. 

147. Earthquakes in California in 1895, by Charles D. Perrine, Assistant Astronomer in Charge 
of Earthquake Observations at the Lick Observatory. 1896. 8°. 23 pp. Price 5 cents. 

148. Analyses of Rocks, with a Chapter on Analytical Methods, Laboratory of the United States 
Geological Survey, 1880 to 1896, by F. W. Clarke and W.F. Hillebrand. 1897. 8°. 306 pp. Price 
20 cents. 

149. Bibliography and Index of North American Geology, Paleontology, Petrology, and Miner- 
alogy for the Year 1896, by Fred Boughton Weeks. 1897. 8°. 152 pp. Price 15 cents. 

150. The Educational Series of Rock Specimens collected and distributed by the United States 
Geological Survey, by Joseph Silas Diller. 1898. 8°. 398pp. 47pl. Price 25 cents. 

151. The Lower Cretaceous Grypheas of the Texas Region, by R. T. Hill and T. Wayland 
Vaughan. “1898. 8°. 139pp. 25 pl. Price 15 cents. i 

152. A Catalogue of the Cretaceous and Tertiary Plants of North America, by F. H. Knowlton. 
1898. 8°. 247 pp. Price 20 cents. 

153. A Bibliographic Index of North American Carboniferous Invertebrates, by Stuart Weller. 
1898. 8°. 653 pp. Price 35 cents. 

154. A Gazetteer of Kansas, hy Henry Gannett. 1898. 8°. 246 pp. G6pl. Price 20 cents. 

155. Earthquakes in California in 1896 and 1897, by Charles D. Perrine, Assistant Astronomer 
in Charge of Harthquake Observations at the Lick Observatory. 1898. 8°. 47 pp. Price 5 cents. 

156. Bibliography and Index of North American Geology, Paleontology, Petrology, and Miner- 
alogy for the Year 1897, by Fred Boughton Weeks. 1898. 8°. 130 pp. Price 15 cents. 

160. A Dictionary of Altitudes in the United States (Third Edition), compiled by Henry 
Gannett. 1899. 8°. 775 pp. Price 40 cents. 

- 161. Earthquakes in California in 1898, by Charles D. Perrine, Assistant Astronomer in Charge 
of Earthquake Observations at the Lick Observatory. 1899. 8°. 31pp. 1pl. Price 5 cents. 
In preparation: 

157. The Gneisses, Gabbro-Schists, and Associated Rocks of Southeastern Minnesota, by C. W. 
Hall. 

158. The Moraines of southeastern South Dakota and their Attendant Deposits, by J. E. Todd. 

159. The Geology of Hastern Berkshire County, Massachusetts, by B. K. Emerson. 


WATER-SUPPLY AND IRRIGATION PAPERS. 


By act of Congress approved June 11, 1896, the following provision was made: 

“Provided, That hereafter the reports of the Geolo:ical Survey in relation to the gauging of 
streams and to the methods of utilizing the water resources may be prin‘ed in octavo form, not to 
exceed one hundred pages in length and five thousand copies in number; one thousand copies of which 
shall be for the official use of the Geological Survey, one thousand five hundred copies shall he deliv- 
ered to the Senate, and two thousand five hundred copies shall be delivered to the House of Repre- 
sentatives, for distribution.” 

Under this law the following papers have been issued : 

1. Pumping Water for Irrigation, by Herbert M. Wilson. 1896. 8°. 57 pp. 9 pl. 

2, Irrigation near Phenix, Arizona, by Arthur P. Davis. 1897. 8°. 97 pp. 31 pl. 

3. Sewage Irrigation, by George W. Rafter. 1897. 8°. 100 pp. 4 pl. 

4. A Reconnoissance in Southeastern Washington, by Israel Cook Russell. 1897. 8°. 96pp. 7pl. 

5, Irrigation Practice on the Great Plains, by Elias Branson Cowgill. 1897. 8°. 39pp. 12 pl. 

6. Underground Waters of Southwestern Kansas, by Erasmus Haworth. 1897. 8°. 65pp. 12pl. 

7. Seepage Waters of Northern Utah, by Samuel Fortier. 1897. 8°. 50 pp. 3pl. 

8. Windmills for Irrigation, by Edward Charles Murphy. 1897. 8°. 49 pp. 8 pl. 

9. Irrigation near Greeley, Colorado, by David Boyd. 1897. 8°. 90 pp. 21 pl. 

10. Irrigation in Mesilla Valley, New Mexico, by F. C. Barker, 1898. 8°. 5lpp. 11 pl. 

11. River Heights for 1896, by Arthur P. Davis. i897. 8°. 100 pp. 

12. Water Resources of Southeastern Nebraska, by Nelson H. Darton. 1898. 8°. 55 pp. 21 pl. 

13. Irrigation Systems in Texas, by William Ferguson Hutson. 1898. 8°. 67 pp. 10 pl. 

14. New Tests of Certain Pumps and Water-Lifts used in Irrigation, by Ozni P. Hood. 1889. 8°. 
91 pp. ipl. 

E 15. Operations at River Stations, 1897, Part I. 1898. 8°. 100 pp. 

16. Operations at River Stations, 1897, Part II. 1898. 8°. 101-200 pp. 

17. Irrigation near Bakersfield, California, by C. E. Grunsky. 1898. 8°. 96pp. 16 pl. 

18. Irrigation near Fresno, California, by C. E. Grunsky. 1898. 8°. 94 pp. 14 pl. 

19. Invigation near Merced, California, by C. E. Grunsky. 1899. 8°. 59 pp. 11 pl. 

20. Experiments with Windmills, by T. O. Perry. 1899. 8°. 97 pp. 12 pl. 


VIIl ADVERTISEMENT 


21. Wells of Northern Indiana, by Frank Leverett. 1899. 8°. 82pp. 2>pl. 

22. Sewage Irrigation, Part Il, by George W. Raiter. 1899. 8°. 100 pp. 7 pl. 

23. Water-Right Problems of Bighorn Mountains, by Elwood Mead. 1899. 8°. 62p 7 pl. 

24. Water Resources jot the State of New York, Part I, by George W. Rafter. 1899. Soe 
99 pp. 13 pl. 

25. Water Resources “of the State of New York, Part II, by George W. Rafter. 1899. 8». 
101-200 pp. 12 pl. 

26. Wells of Southern Indiana (Continuation of No. 21), by Frank Leverett. 1899. 8°. 64 pp. 

27. Operations at River Stations, 1898, Part I. 1899. 8°. 100 pp. 

28. Operations at River Stations, 1898, Part I]. 1899. 8°. 101-200 pp. 


In preparation: 
29. Wells and Windmills in Nebraska, by Edwin H. Barbour. 
30. Water Resources of the Lower Peninsula of Michigan, by Alfred C. Lane. 


TOPOGRAPHIC MAP OF THE UNITED STATES. 


When, in 1882, the Geological Survey was directed by law'to make a geologic map of the United 
States there was in existence no suitable topographic map to serve as a base for the geologic map. 
The preparation of such a topographic map was therefore immediately begun. About one-fifth of the 
area of the country, excluding. Alaska, has now been thus mapped. The map is published in atlas 
sheets, each sheet representing a small quadrangular district, as explained under the next head- 
ing. The separate sheets are sold at 5 cents each when fewer than 100 copies.are purchased, but when 
they are ordered in lots of 100 or more copies, whether of the saine sheet or of different sheets, the 
price is 2 cents each. The mapped areas are widely scattered, nearly every State being represented. 
About 900 sheets have been engraved and printed ; they are tabulated by States in the Survey's 
“List of Publications,” a pamphlet which may be had on application. 

The map sheets represent a great variety of topographic features, aud with the aid of descriptive 
text they can be used to illustrate topographic forms. This has led to the projection of an educational 
series of topographic folios, for use wherever geography is taught in high schools, academies, and 
colleges. Of this series the first folio has been issued, viz: 

1. Physiographic types, by Henry Gannett, 1898, folio, consisting of the following sheets and 4 
pages of descriptive text: Fargo (N. Dak.-Minn. oy a region in youth; Charleston (W.Va.),a region in 
maturity; Caldwell (Kans.), aregion in old age; Palmyra (Va.), a rejuvenated region; Mount Shasta, 
(Cal.), a young voleanic mountain; Eagle (Wis. ), moraines; Sun Prairie (Wis.), drumlins; Donald- 
sonville (La.), river flood plains; Boothbay (Me.), a fiord coast; Atlantic City (N.J.), a barrier-beach 


coast. 
GEOLOGIC ATLAS OF THE UNITED STATES. 


The Geologic Atlas of the United States is the final form of publication of the topographic and 
geologic maps. ~ The atlas is issued in parts, progressively as the surveys are extended, and is designed 
ultimately to cover the entire country. 

Under the plan adopted the entire area of the country is divided into small rectangular districts 
(designated quadrangles), hounded by certain meridians and parallels. The unit of survey is also the 
unit of publication, and the maps and POSER EONS of each rectangular district are issued as a folio of 
the Geologic Atlas. 

Each folio contains topographic, geologic, economic, and structural maps, together with textual 
descriptions and explanations, and is designated by the name of a principal town or of a prominent 
natural feature within the district. 

Two forms of issue have been adopted, a ‘library edition” and a ‘“‘field edition.” In both the 
sheets are bound between heavy paper covers, but the library copies are permanently bound, while 
the sheets and covers of the field copies are only temporarily wired together. 

Under the law a copy of each folio is sent to certain public libraries and educational institu- 
tions. The remainder are sold at 25 cents each, except such as contain an unusual amount of matter, 
which are priced accordingly. Prepayment is obligatory. The folios ready for distribution are listed 
below. 


Area, in |Price, 
No. Name of sheet. State. Limiting meridians. Limiting parallels. | square in 

miiles. |cents. 

IL |) Ibias! 2 cossoacseeooeece | Montana 110°-111° 45°-46° 3, 354 25 

2| Ringgold ...... Knee. \ 859-85° 30! 342 30/-35° 93) | 95 

3 | Placerville....- California 120° 30/-1219 38° 30'-39° 932 29 

4 Kingston... -- | Tennessee 849 30/-85° 33° 30-367 969 25 

5 | Sacramento-... | California... 1219-1219 30/ 38° 30/-39° 932 25 

6 | Chattanooga | Pennessee -- 859-859 30! 359-359 30! 975 25 

7 | Pikes Peak (out of stock)..---- Colorado...- 105°-105° 30/ 38° 30/-39° 932 25 

8) S@WANCCase seem eee eens ene Tennessee - 85° 30/-86° 352-359 30! 975 25 

9 | Anthracite-Crested Butte ....- | Colorado: 106° 45/-1079 15° 38° 45/399 465 50 
Inginiaeesesee 

10 || Harpers Ferry..-..-....-..---. fives est Virginia -. 77° 30/-78° 399-399 30’ 925 25 
| Maryland. pocsece 


1016 pp. Price 60 cents. 


1886. 8°. 


Mineral Resources of the United States, 1885. 
Price 40 cents. 
Mineral Resources of the United States, 1886, by David T. Day. 


vii, 576 pp. 


60 cents. 


Mineral Resources of the United States, 1887, by David T. Day. 


50 cents. 


Mineral Resources of the United States, 1888, by David T. Day. 


50 cents. 


Mineral Resources of the United States, 1889 and 1890, by David T. Day. 


Price 50 cents. 


Mineral Resources of the United States, 1891, by David T. Day. 


50 cents. 


ADVERTISEMENT. IX 
Area, in ‘Price, 
No. Name of sheet. State. Limiting meridians. Limiting parallels. BavEEE | an 
mules. cents. 
11 | Jackson ........---- Soness00c59 California......- 120° 30/-121° 389-389 30/ 938 | 25 
Virginia -.- = | 
TP} |) DOR AID Soeeeao ceccmoascs SoS {Heat 0 3 | 82° 30/-83° 36° 30/-37° 957 | 25 
ennessee - -- | 
13 | Fredericksburg...------------- (yer vand PE } 772-772 30! 382-382 30/ 938 | 25 
THBie Staunton we. tee es cea eeeneeaee A Woet virginia. \ 792-792 30! 380-389 30/ 938) 25 
15 i Lassen Peak......-.----------- California. . at 1219-1229 40°-41° 3, 634 | 
iG} |) Tera Os ncencceenageesqooeas: Oa ee cae \ 83° 30/-84° 35° 30/-36° 925} 25 
17 | Marysville. - sle@aliformia.-- == 121° 30/-122° 399-39° 30/ 925 25 
18 | Smartsville -- .-| California. 121°-121° 30/ 399-399 30/ 925 25 
Alabama 
19 | Stevenson .......---..--.------ {Geonaia } 85° 30/-86° 34° 30/-35° 980 25 
\(Tennessee - 
20 | Cleveland......----------- --.--| Tennessee - 84° 30/859 35°-35° 30! 975 25 
21 | Pikeville -......--.-.---------- Tennessee 5 85°--85° 30/ 35° 30'-36° 969 | 25 
22 | McMinnville...-..-..---.------ | Tennessee .---- 85° 30/-86° 35° 30/-36° 969 25 
23 | Nomini vee 76° 30/770 389-380 30! 938 | 25 
24 | Three Forks.-..---.--------... Montana... = 1119-1129 459-469 3, 304 50 
25} |) LOWE sss seaceosc Tennessee ---.- 849-819 30/ 35° 30/-36° 969 25 
26 | Pocahontas (west virginia. |p 819-819 30/ 37-379 30/ 951 25 
27 | Morristown....-...----------- --| Tennessee 3°-83° 30! 362-369 30/ 963 25 
|( Virginia .. =e 
28 | Piedmont..........-...----..-. {dear land aeacoc0 \ 79°-79° 30’ 392-399 30/ 925 25 
5 West Virginia...) | 
Nevada City - 121° 00! 25//-121° 03/ 45/’ | 399 13/ 50/'-39° 17! 16” 11. 65 
29 | Nevada city... Grass Watley} California ...-.- fine Ol! 35//-121° 05! 04! | 39° 10! 22//-39° 13/ 50// 12. 09 \ 50 
Banner Hill - 120° 57! 05!/-121° 00’ 25’ | 39 13/ 50-399 17/ 16” 11. 65 
a F x Canaan bs 
ellowstone Na- }Canyon... aoe: ie Here 
30 |{* tional Park. Shoshone. Wyoming ...--- 1102-1119 440-450] 3,412| 75 
ake ....-] 

31 | Pyramid Feak -.......-.--- California ....-- 120°-120° 30/ 38° 30/-39° 932 25 
32 | Franklin este Pocngese \ 792-792 30! 382 30/-390 932| 25 
Saal etdenameyegascen bare Ba Ce ca Hee Bat West Virginia .. ‘a S 
33 | Briceville....-....--.-.------.- Tennessee .---.- 84°-84° 30/ 369-369 30/ 963 25, 
84 | Buckhannon........-.--- West Virginia -. 80°-80° 30! 38° 30/-399 932 25 
35 | Gadsden .....-..-.------- Afabama/......- 862-869 30/ 349-349 30/ 986 29 
Bo |) LM. sesso csedonusseoo Colorado...--.-- 104° 30/-105° 389-389 30/ 938 50 
87 | Downieville ...-....----- -| California....... 120° 30/-1219 39° 30/409 919 25 
38 | Butte Special..-.--..--.- 'Montana.......- 112° 29/ 30//-112° 36/ 42’ | 45° 59! 28//-46° 02/ 54// 22. 80 50 
39 | Truckee ..- 2 California. .-.--- 120°-120° 30’ 399-399 30/ 925 25 
40 | Wartburg .-.--...---.- Tennessee .....- 84° 30/-85° 369-369 30/ 963 25 
41) Sonora. 5... ---2---.0.- California ..-..- 120°-120° 30/ 37° 30/-389 944 25 
42 | Nueces ..-...----- -.--- PLOXAS sees = 100°-100° 30/ 29° 30/302 1, 035 25 
43 | Bidwell Bar -.----...-. California .....- 1219-1219 30/ 39° 30/-40° 918 25 
44 | Tazewell.......---.---- 2 (Weee vag seal 81° 30/829 379-379 30/ 950 25 
45 | Boise ----- eee -| Idaho ae 1169-116° 30’ 43° 30/-44° 864 | 25 
46 | Richmond ~ Kentucky --.--- 849-849 30/ 87° 30/-38° 944 20 
47 | London -| Kentucky -.-.-.-.- §49-84° 30/ 3792-3792 30/ 950 25 
48 | Tenmile District Special. -| Colorado. -.....--. ea 16! | 39° 22’ 30’-39° 30/ 30” 55 25 
49 | Roseburg.....-.----..- “|| Ore - 25505 123°-123° 30! 43°-43° 30! 871 25 
50) pHoly okesee sss ee een Ronee © \ 722 30/-73° 422-499 30/ 885 | 25 

z STATISTICAL PAPERS. 
Mineral Resources of the United States [1882], by Albert Williams, jr. 1883. 8°. xvii, 813 pp. 
wot J rJ ’ PL 
Price 50 cents. ; E 
Mineral Resources of the United States, 1883 and 1884, by Albert Williams, jr. 1885. 8°. xiv 
y J ? 


Division of Mining Statistics and Technology. 


1887. 8°. viii,813 pp. Price 
1888. 8°. vii, 832 pp. Price 
1890. 8°. vii, 652 pp. Price 

1892. 8°. viii, 671 pp. 

1893. 8°. vii, 630 pp. Price 


eeXe ADVERTISEMENT. 


Mineral Resources of the United States, 1892, by David T. Day. 1893. 8°. vii,850 pp. Price 
50 cents. 

Mineral Resources of the United States, 1893, by David T. Day. 1894. 8°. viii,810 pp. Price 
50 cents. 

On March 2, 1895, the following provision was included in an act of Congress: 

“Provided, That hereafter the report of the mineral resources of the United States shall be 
issued as a part of the report of the Director of the Geological Survey.” 

In compliance with this legislation the following reports have been published: : y 

Mineral Resources of the United States, 1894, David T. Day, Chief of Division. 1895. 8°. xv, 
646 pp., 23 pl.; xix, 735 pp., 6 pl. Being Parts III and IV of the Sixteenth Annual Report. © 

Mineral Resources of the United States, 1895, David T. Day, Chief of Division, 1896. 8°. 
xxiii, 542 pp., 8 pl. and maps; iii, 543-1058 pp., 9-13 pl. Being Part III (in 2 vols.) of the Seventeenth 
Annual Report. 

Mineral Resources of the United States, 1896, David Tf. Day, Chief of Division. 1897. 82. 
xii, 642 pp.,1pl.; 643-1400 pp. Being Part V (in 2 vols.) of the Nineteenth Annual Report. . 

Mineral Resources of the United States, 1897, David T. Day, Chief of Division. 1898. 8°. 
viii, 651 pp., 11 pl.; viii, 706 pp. Being Part VI (in 2 vols.) of the Nineteenth Annual Report. 


The money received from the sale of the Survey publications is deposited in the Treasury, and 
the Secretary of that Department declines to receive bank checks, drafts, or postage stamps; all remit- 
tances, therefore, must be by MONEY ORDER, made payable to the Director of the United States 
Geological Survey, or in CURRENCY—the exact amount. Correspondence relating to the publications 
of the Survey should be addressed to 

TxE DIRECTOR, 
UNITED STATES, GEOLOGICAL SURVEY, 
WASHINGTON, D. C., June, 1899. WASHINGTON, D. C. 


eries. 


Ss 


Author. 


Subject. 


[Take this leaf out and paste the separated titles upon three of your cata- 
logue cards. The first and second titles need no addition; over the third write 
that subject under which you would place the book in your library. ] 


LIBRARY CATALOGUE SLIPS. 


- United States. Department of the interior. (U.S. geological survey.) 


Department of the interior | — | Monographs | of the | United 
States geological survey | Volume XXXIV | [Seal of the depart- 
ment] | 


Washington | government printing office | 1899 

Second title: United States geological survey | Charles D. 
Walcott, director -| — | The | glacial gravels of Maine | and | 
their associated deposits | by | George H. Stone | [Vignette] | 

Washington | governinent printing office | 1899 

4°, xiii,499 pp. 52 pl. 


Stone (George H.) 

United States geological survey | Charles D. Walcott, di- 
rector | — | The | glacial gravels of Maine | and | their associated 
deposits | by | George H. Stone | [Vignette] | 

Washington | government printing office | 1899 

49, xiii,499 pp. 52 pl. 

[UNITED STATES. Department of the interior. (U. S. geological survey.) 
Monograph XXXIV.] 


United States geological survey | Charles D. Walcott, di- 
rector | — | The | glacial gravels of Maine | and | their associated 
deposits | by | George H. Stone | [Vignette] | 

Washington | government printing office | 1899 

4°, xiii,499 pp. 52 pl. 

[UNITED STATES. Department of the interior. (U. 8. geological survey. 
Monograph XXXIV.] : 


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