THE PATAGONIAN PAMPAS THIS BOOK AS” WHE (PROPER ie OF Frederic Brewster Conomis ORCHARD ST., - > = AMHERST, MASS Peclkinccs by Ce. Rav ; eae 14°74 Ske Grant lo, Ysedcr tu Memory of Remington Kellogg Dy Mammalogist sit . ie ae : Hey Las Paleontoldgist : is ayy AS. Sa). See es ee Pree a - if. ee i ied ou ae if Pe way Pi t re A ee - i . i Ve Ay oa eat ‘ a -' MAL if : aN la a : : ae ay Os Bate ete! Par on a eG ‘ toe 7 / at ae f ae ee a ‘ee ” oy e os a renee. ne ' vider th Some . ae: nd? Care: if} ys 5 Me Phe Ss ¥ , a ae a. wt ees i SPMRLD Bash” x rn M! av? ay a Oy ae ra ie 4 rj sha, ae it be % ‘ v, iL bis rf cf ‘ts ee: an a in Yr ¥ a ae ae A 2 ov) en ciel ae Soy Y Ce, - — oo Gi ale ati a arate Pt a ne ey, 7 \ ig i en ee Oe ni a? ne ee ON i , i a Sie } QF, . a > a a fiat Ce - pe 4 io te ht | oe ne ¥ ra AN ay “y a tA De Se ve : a ay. aA) ey f 7 of ; = I< \O 6a ‘ a : ai ) ae ul 7 =, mad ri i tn i m j - oy 4 ee Pel: pe athe a4 i’ Pane 7 a ; a Lis oy, 0 7 ‘ : oo) a f ‘s a. ey: rae 1 ¢ by i Ae Se Re — Dy a ov “a8 7 ~ 1A Sah a Vj “ : \ Deni La cm : ay a Ps my : * 7 7 ~ \ a a ae va en eee ft os ‘« aay an a , + sh ke! a i 'y » ay —~—e : ‘a pol j ’ ¥ Ye 4 eh , : ny Aaa 7 7 - : eee | f Cae p. rt ih nv 7 ea i mY , ¥ - ‘a i”) cone ‘am ra Ss ia Ae ° ae a By an if a >> cae 7 i. : ’ ad ; mire —_ : a oor 7 * : Nee nh se » yee ma) , ae ays Dy cae 4 ie ; } ® 3) se Pim hades + oti a 7 “4 a> i ; » Oke Woe, yl ay ee Oy see AA, ras : omy r a? ' 4 / ta Reo be ee Pi ‘a a ae yet . MOTO 2 at NY oe oe A ee ‘ ee ¢ Nha © 4 my P e ; Tare See! Sian L Aral Blince’ i ret fe vi A ; aoe _* i " oY as ae 7 ina ‘ rm) yy i 3 >: ‘i a Oe ‘a = me 1 avin A \- < me ( me e,* e Same gee 7 Te 7 ; Po o) yp * rt }: : IT ba . ey are x ee” ; i ) HY og , fi wa oh { |) Sl ’ Le ne a Sa ; c Dm” i dal oer ee val y Les pe % ewe OS Mae is eee ag Loup fe ' eo ire Lai “ae 7 By NA Bea ee rey ae aig > pom are ieee a ia yt y a ’ 4 J Ai ob Bal s% yee Dy J), oe 3 i i> ee 7 Oe ‘— x Fy ye Se — o> eet o Ve 6 as hl ; 7 : ry 4. SS > om - ; a so (i |i a ee. Se oe ‘sg Pues 7 7 ae 4) woe ao : arse ad z weer! - 7 a as oe oe As J Pena We. Le Fi : : a oe. : i: = eh ‘ ‘ Be aay L kG ae A a ne ls) Ss chy eae ai ai i= 1 iat i iol) Mh AGES ie ae) ae YT > Ae MARYLAND. GEOLOGICAL SURVEY PRINCE GEORGE'S COUNTY BALTIMORE THe Jowns Hopkins Press 1911 wae ; <2 > a_> a aie. sab? * 8. Aha! an %, Se) an a - : ys . : 4 oo” al li . J ot _ . 4 a y > = < ee dt | Aa ~ Care oy, aie y i aes ¥ ae hs ve ne yea a. = ’ oa 7 7 ne 2 ee ae ; oy = =a aie 7 7 eo a ae 2 a Me Ae. a ae - a > 7 Pe’ ae) 2 4? v€ * i r “as - oti) | 7 e 19 ae a a ar *. de 7?¢ ar _ - = : e.~ +4 Lae 95 'eoe Py fe > o 2S ty ye wri * = Poy & =e i ¢ :) al wee Se Sa en ue " . : be ‘ ree 2 <> “I Py J 1 7 ~*~ COMMISSION i AUSUEN La-CROTEERS, : : : PRESIDENT. GOVERNOR OF MARYLAND. WLAN BY CLAGGETT, COMPTROLLER OF MARYLAND. IRA REMSEN, : ; ; : EXEcurTIvE OFFICER. PRESIDENT OF THE JOHNS HOPKINS UNIVERSITY. RWS lENGH SPB: 2 : : : SECRETARY. PRESIDENT OF THE MARYLAND AGRICULTURAL COLLEGE. Briss 5 re et oe Ss y 1 ae ; heey : , iy (2 Ae, Orn) a aa ~, ie mn] hig r i ¥ my cng 5 a a oo it: . | fis ied Sey pia es rity Ph ie Wa a yA a RO ehh oft a} ep he. : wore 7 i" if ra rues a ed, j i aa a nt we ioe iW od - a re na o, Wes yi ne 7 air ae “ . ‘? (aoe a Bry oe? ia a et mi cae bay =) ret S Me : yas He vl ’ ~% ih ; r A 7 tty ‘ f Sie a aes. ees as Site Bar Un : mis a ris ( Ave * Bu ay eae i > tired : mul 4) sate Co is! ‘hie ie tae By a tik \ et Siren J De ae ‘j axe ae: \ es ape ay is vy “a ay ve: acta ; 7 ie : =) . iy ie Bete, vite ie errs be flrs aa Ae i a ak a - re a aes : ee aia To Oh t4 “ oN iy oe ae wy ayers? ey an Pa Ot iu Pa ty poe AP more A n z ca) cary, + ars : oan A A +5) tit be \ ‘ 4 an a, ae an as ra! an 7 ie ia eee ay a) 7 Uj " oe aa - Lon ca a yee io . : (uy) ile Ri as 7 ets 0 ae ae ts ; PAS Ct Aah tn i as as Tete oP) ih ie Cee al © ue tae a cad vie eS = 7, Bite: Ay Nb 7 is ME a re a ithe Bin. oa bi q eg ni igi Se au ae ey i, ob an " etn sea ue 74m Pay ale y » } : f ay | ays Mt ‘ sulk i. i ou Aen aa ae ns . ae ; meee aseg ah ra #1 —~ phi st SCIENTIFIC STAFF Wm. Buttock CuarxK, : : : Strate GEOLOGIST. SUPERINTENDENT OF THE ‘SURVEY. Epwarp B. MatrHews, : : ASSISTANT STATE GEOLOGIST. B. L. Miter, . : : ; : : GEOLOGIST. CORKS Swartz, : : : : , : GEOLOGIST. E. W. Berry, : ‘ : ; : : (GEOLOGIST. A. Bissins, . . 4 ; A : : (JEOLOGIST. Also with the codperation of several members ot the scientific bureaus of the National Government. LETTER OF TRANSMITTAL To His Excellency Austin L. CRorHErs, Governor of Maryland and President of the Geological Survey Commission. Sir:—I have the honor to present herewith a report on The Physi- cal Features of Prince George’s County. This volume is the sixth of a series of reports on the county resources, and is accompanied by large scale topographical, geological, and agricultural soil maps. The information contained in this volume will prove of both econom- ic and educational value to the residents of Prince George’s County as well as to those who may desire information regarding this section of the State. I am, Very respectfully, Wau. Buttock CLarK, State Geologist. JoHns Hopkins UNIVERSITY, BautTrmMoreE, March, 1911. ts CONTENTS PAGE SRT DYN GID, RR dees Oc OR an En BO Or a Oe Me OO icin. iia Soe aca 17 TUNFIMEO LD LOROUMI GIN Aye, Seen BCRlprais oe Eerie cee SOitts Sitar ico on Aaa ae 21 DEVELOPMENT OF KNOWLEDGE CONCERNING THE PHYSICAL FEATURES OF PRINCE GEORGE’S COUNTY, WITH BIBLIOG- RAPHY. By BENJAMIN L. MILLER.......------ 20s eee re rere cee 24 TINAO ISON? orobooocopdcapn Uc OOD dpeS HH os UDO oDoD OSC oomed Ss 5 yor 24 JARRING) ARIONPU aye padeasogcebooubedeounocUpe ooo ob c duo dood aba U Ook 24 Giemerail) C@iiari| wench, oosaarceoucopdeocdanots cosoodoom@h a dab boa 26 Historical Review of the Various Geologic Groups Fein I ne SE OE 27 The Crystalline Rocks of the Piedmont Plateaus siete eek ee a rai em OWiGlun © RETA GCOUSt sepia ole ioicke eietelle let eyre cole oes ereievier= Topeo (oso 28 Mle dlp per aCretaceOUS.ojcrccinc cle 2 oe eieryete ie nee Aa iege = apa iene > 29 TWINS, DOCG e.c Bo ea bic Dono. comin 0 diin Cmeingc nla e cya mick orc Cloiic 30 dnhavew ol BYG (eo oane Pan rae in tin PO sor nr ene re ie ranac ein cars Sci eke 31 The Pliocene (?) and Pleistocene. ........-.-- +s. eee reece ects 32 lediniitoyearey Wits oct he eR Cpe boo Doe actin Deo Oban Om ct Cenc titi ts 33 THE PHYSIOGRAPHY OF PRINCE GEORGE’S COUNTY. By BENJAMIN iby IMintilin ies a0 So neo nue bb owes od ooo On cidade mod Op Oop odn.ed o 6 Diao nk 69 MESPURODEOORY ore sre tie cic ile meters are rere erarake ine! shee eisteyris oe Shere eur ee saris 69 MOPOGRAPHICG. DESCRIPTION s. 4 ely ci sie keels) lose ele ere trie eo on oie) chance 70 Topopraphic Weatures.... 1. .2-cen esses cscs ce een te mene 3 MING) INNES oo ao obks SAO oe oo au amon On oo obeUDOO DOO UGcon Ope ooo 3 Te eePenyC Uc mee lenin peti wold cts crete exe eeceta cy Jaen to eye rotate ehh no cee) lames Sees ae 73 Spero! IRewhin Aah vcs o cunaoe Soman onus Soo DURUM PO udiorE ban Sa0C 3 WAKEonmeo IDbhine soos opoorcdopomeocunvmoanceCconemoguDcmocy Mopar 74 APN NOXE) Jee Nhtle 65 GA ae cose 60 Go bo Op Gl nh) a cilbic tino crdcleimro acim eG oi cai 7d The Drainage of Prince George’s County.......--+----+-++:; Pinyin 3) Stray IDileSioanc ob sogcs ooDnecdouted obONS Doma DO PUInUrAS Fool aD Cc 75 Mid water mOSCUALIGS ee os cia seks selec chaise token as eds) olemeyer score oie ne ne 76 TOM POLOMACE RULVGIe ites cient tee eee ee deve ee cn elctiol spicier p susunts, aicuses toler {0U Tats ayo IRIATEIRy ooo ccomoeuo sor yoooNnanbean Cec Gudoponay 6 bimL 18 AMONIeIRANDIsae ISUKRINONAT Gee 5 oecoavscousoudds pUeDoadae Ooh UCE Oma me OOS O 79 TWO MMALAYV ELLE. GLAGE sacs ata clos «eles ieee mir ve oie oa Oe sie esi cie Creede wis) % 28 7 TMi Shoumnokerdenael Qieke@c cu oodconeGosdcgecueconeodU DD oD oUoDS DEG OOIOE 80 aia AWaleoineoy SiiiKeio.06.05 200 codhavb00dn Moco ocip a SOU ROD OOIOe CO cobb Oe 81 Ting “syle GibEsocecccosc tacuospo eno de cus eg soon D da UUr om OGo OKC 2 MINGMIRCCOTIL IOLA GS. re eae i she ais cere = silo neo saeco woes Si lest e Sisie 82 THE GEOLOGY OF PRINCE GEORGE’S COUNTY. By BENJAMIN L. IMMEERIIR Ss S56 0 Boo oe ere bu 0 or Oe DGD CO Oe CIO CIRIO OIG Eel SIOID CeC inca 83 TROON op odna Sapncb ob oeHd 6000 50 0 ROOD Uc Chain CICLO cK: o 83 ‘Dean (ChoyasnoNarieiinin, IX 3 Bape b on en ooU mou eC b.Us Glib. Orbic cS OmimiDDIO Cm Oita. 84 CONTENTS PAGE @ranite i GMeissc. sisi ciclse wie, 400s bole exe elec ed oko epee Te ateeieltee eraeeiate oie ay ers 84 GaDUTO. ee sree cs he eek he a role 8 els eerie to etek IIe hore sieicr oie slereietors 85 Than Owe CRECTACKOUS HMORMATIONSs 1 -eeeieine cena eiieiereiae elaietel- 85 TEE POTOMAC “GROUB 6 sored oslo alors a 5) is rovecot hcueuere ohare eRe en a ateN Aue tera oito rots 85 Thew Patuxent Mormation: css dee Seis ee eis seketar = ites 85 Areal. DISthibwtiOns. <2... s ectee slsos tenor eee eee tat ee oh ono reieh tran otal = 86 Characterzot Materials: . 2. sco cere eee eat nee niet a 86 Paleontologic: ‘Characters. :)\..75 « se honole aiere 105 SHUT oye IWS OH GNSE whey peetcre Be aesculus tia Ocpar eter Baek cece ies tm tec citi canoer 105 ELE VELOCHNE | MOR MATION GS sain tsts cin cus 2 oust ele eievel sichelis sient s}icnelsiisra,s cus, ones. iel eleitelelts 106 SET Toes CHGS AIP HV AIKaWs GRO WIR A ca cyerre la chicyet a Ruoletete, emis Sm. cilvalensyebaiclielle.o ile cvereusiale) eransieh 106 HCMC alverte eH OLIVET OMe sicicre oes cretovereie to cine shawere siete © cushchste mis Sitneiecoveh ote 106 AT CUED ISTP MELO Ms sirteire hates tiaenetes tna eiciah sialion hoi es) eke eaaauer amelie elas 106 Charactenmohw MAtTeHIAlss aciiths.c epeatesere sets cee ele ye. a eased- 108 SUD GAVASTO MS frctrecsus syste ciel octet thos cietearveleusscveteus (erste were ale aielarar auehoue a © 112 MSM MaAtayetlersMOGMIAtTON t ere, cee cus te-slevch gcc aisles 5. esi 4 soe o iy sierehs ol sie) omens 112 Are alee DistribitiOmmcmmis cece acre te oe seer er. Gis cl cote cece ee eee 127 sedimentary Record of the Crystalline Rocks. ..........-..5296200. 127 Sedimentary Record of the Lower Cretaceous................ Huse eles Sedimentary Record of the Upper Cretaceous.................-..... 129 sedimentary Record: of the Hocenes:4-o55 s2 462) ee eee 131 Sedimentary, Record ofshemNllGcene sere eee 132 Sedimentary Record of the Lafayette Formation................... 1B Sedimentary Record of the, Pleistocene... 422) ..0 3a eee 133 THE MINERAL RESOURCES OF PRINCE GEORGE’S COUNTY. By BENJAMIN, Wa. MILLER. fis waco ae oe ii oe ee ee 137 LEN TRODUCTOR Ys: dois «jigs hs AE ae Dh patch chee eae ee NSH THR ANATURAY, JOEPOSITS... 2.4 :4\4 cw theless oe ae Ie 1kS37¢ AOS CVAY Ses cin avin, 150 THE SOILS OF PRINCE GEORGE’S COUNTY. By Jay A. BonsTEEL... 151 NTI AONCINOAY! 4 coe oben oa o be .on.6 oo an omord pele cicle Hib cue cl c.g BimioiAcle cocina oInD alisyil PIBEHE pS OIE UINGRES inrebal feat is cya psteCele ia tlainls G2 Fl o/h n me aay ersiel Ciclo na 152 ine (Crolllimesioin Stwachy IWoehie ano gotoc soso uuedosupdcccuooGr on coy ooK 152 Mine. INiOmmolltc Seyal.a> sa oomsoosconnn sooo TA de genes Se erry: 158 Tne WweRsijoneible, SEMiGlsoofnueccosueboodoorHamopooroodcgoo Goo ONb Dot 159 mae Wwrhnaleore. Sbinlasds oamacie 460008 oda om Sma mucome codon ditio bigin ido dion 161 AMS Siegen, (Chahiello eon eas ono mee od aoc eogooe Uo Domo docc ToC 162 Tne. Wewmeudohwonin, IMORWIS kao eGo os ony o RA amo Domo colon Peo bmamondaldc 164 aM lromehookionan, (Gianiellhia, Iboyhilng susan snap od oo pd ood cdo Oba oo oC 166 ane SEISSENBenS) Ibo. Ls os Gb d eco auld me aD en thocaan pinto d clo coli noo ao 167 Tne SAsenintas Seine IWeEWils 6 dcccomcesacbnachcodocbooce doduseueboc 167 pina INGO IL~RNIN, «4 doddee eats 0S 4 coe BobinG Geodcoocua anh sos UC 169 Mhen Susquehanna Clay. oo). se ce eer et cle rie ne ern Oe IAL The Susquehanna Clay Loam..........--..-. sere e teen eee nee il 7/83 Tavs, IDiwoua, WOlhees ode oes aqsb co och Hed cnn Gedo oma oma coud san oho 174 aia (Cereril WIG ILO INNS. goo cote h ae Moo ese poe aol poe mDocom onde moe G75) AN aVe. - INEBVGI Ohi so Sls dea Bo SSDS OS a clei baa Sito Maneater coor sitvOnaitaone icra choc iLY(#/ CIEE MAG RG UNIAN Auli ©) OID TT OINIS cfenatretienie lelfeiisiicliete) eye ells) allaiieria (ole ef'+) e\leiieus) 188 TMaa a AG aDT, COWNDDIEUONIS 4 6 oo aecooddocnceseads oe Gon oun odomG Joe Hloldo > OH [PASHAN he Sela oldks a iioio ck oa choitio Oiclote eicacie mecicaona ian el otctolelo ra caescuaicno arnt ow ANsua \WWinlNimenon Ge INGEN eIsO igo boo do ue ea ee o onuD Oooo be omomas ob loo G 204 THE HYDROGRAPHY OF PRINCE GEORGE’S COUNTY. By F. H. INGTNIDIIG. das wild eig Sacha Bin clam ono Ottig Graney Bent oronol cy oRORntCNOlG omic RO normaceOkOra Orsi 207 INTRODUCHORAS Sine saa dive bo od ocd oh oben Delo onic oie mae cmnreDeincrs oad reeIpiis Soo 207 THE PATUXENT RIVER DRAINAGE) BASIN. «<0: -2-s0-0500 ++ es es eee nese 207 Tins) IPynbbdcionn IRGAWEIe ele IDEWbbRES Goosen se ohesoooo GoodeouUG ease obE Oo auc 208 Wyegiad, Jieehaela wwe IYO, lGSh~etes oo oo mene ubmoo oo uo ees boon oO oOC 212 ANTHE CORY TRURHEIPD A 6 oa tsa aon Glo 64 eo000 0 bod Ou Uemomeapioe Hola omc coy bao to Diltes CONTENTS PAGE THE MAGNETIC DECLINATION IN PRINCE GEORGE’S COUNTY. PSG CAS BAUR) occ, a! i bool e oe, shale lehete pauls ACER TORR RRR RCIE RRR eae ietseeh 215 TNTRODWCRORY ) cia cs lars wie icicle) oo ets os sienevelo codeine te e) Cenneien nel Neen Me RRR iarcusitono-li-ik 215 WMIEBEDIAIN SLGDINE es clays sig-s aie ove, ones oie: euchensi easels) cle pete hele e Rica mai aieiereie pe Reteuetstclt- 215 DESCRIPTIONS OREO TATIONS < s « o: cic ere om ol onsiel) oo here ene Reiterates eet ame need men 216 THE FORESTS OF PRINCE GEORGE’S COUNTY. By F. W. BEstry.. 219 MNTRODW STORY: cies sac cnc0e ovese ale. < ctue ov ovchare laneus Perea ener netedete tehet saeteeweic neh Netreme eases 219 THEN DISTRIBUTION OF THE. HORESTS. . «Jeane once eerie 219 MER SHORES TW GE Y.PEG)s so sic. os nisl es silepa sie bete Rie Teela neue eee Nene aCe Eset Ronen newer: 221 MixedhibtardwOOd) “Lp Gi sda ais wc secrs cles e oil ree meen neta ne nc rent eee 221 1EATH ey Lah as) esl OA 01: eer ee eR ee eres eC out o\o 4 Go olmid bin.no ab Gob a4 o's 0 dic 221 ard wood-Pime. ‘TY Me seit oc: & aysisa els-2 6 ie Ra eo ee eae are ee 224 Tre SAND OR ALEMBER SD 1S) \VeATUIE ar carne eee reeeene ne see teen eae ie einen 225 Menrchantable Hardwoods... ccs 0 ctetacre ccc teens nee n eee cnet ated merece 225 Merchantable (Pine. o... ...4 ss 2 di 5 < bis aivieee crore tee esate otate ey ei anne geet 229 G@ullede bland WOOG i 2 os 3% sss aio s wale are ee eI ee een ae ore 229 Culled, Hardwood and! Merchantable (Pines ys ayer r een eee 229 Mand wood “Saplings... 56.5 sc ino sole er a eo aeons 231 Pine @SaAplings ois s. ¢ee ee ¥ Sse we de cqenel ne SOO OIIE, ene Se aR Ie ener 232 BISTVOR ONATIVE’ TREE SPECTES: = ...0. 0.5 says = 2 eie ee alee Ceteneh onto eon emo 233 Ak LMIPORTANT COMMERCIAL, TREES: . flee cles ae oe orci ie ere eee ene letenete 234 TTS OAs oie aite nee fasek Riera and seco \Sse (0: 33 215, 6 See ed ene Re eR OER eae 234 Yeon (QU eUst dh) (ne ee Pn ER es hema 0 boa 60 OO colo 201 235 Mies Vewow? Poplari.cs ss 2). 6 cjove.cid-srne fe. tae ere tetere arei eRGT ROU Ronee na 235 UD neat Sor e0 | Ove £3 0 ole rien Pity ri Sno ino uididoo vada do 6b 235 “bl aveven! 24215 en Cab 000 pee aera isrins Anatom odds cco Udo ouoo eke 236 AM oom bg ¢0) a a ne tee GG Gon en GhObcod C0 OGaOC 236 THe. SRE: MCCOMAS: wcke¥s a /co0.a/o castes: ti age ele AO eRe CIR cea nee neem 236 (PK SPRESENT! USED OF THE FORESTS: .c2-2 4 oe) eee eee een Cer reer ioente 236 15100) ¢ ee ne cre tr AML Gis on moO GoGo Aatboa a4 oO 36 COGEWOOG> 5.5.8 toed ace aid otra ek eee Oe ee eer 237 PA pWOOd! Soyo aie sis 1830. Conran, T. A. On the Geology and Organic Remains of a part of the Peninsula of Maryland. Jour. Acad. Nat. Sci., Phila., vol. vi, pt. 2, 1830, pp. 205-230, 2 plates. Deposits of Tertiary age about Piscataway and Fort Washington are described and correlated with the London clay, upper marine. Several new forms of fossils are described. On the basis of the fossils the Tertiary deposits of these two localities are declared to be older than the Tertiary of Calvert and St. Mary’s counties. Morron, Samuet G. Synopsis of the Organic Remains of the Fer- rugin on Sand Formation of the United States; with geological remarks. Amer. Jour. Sci., vol. xvii, pp. 274-295; vol. xviii, pp. 243-250, 1830. The writer describes fossils from the green-sand marls of New Jersey, from the Deep Cut of the Chesapeake and Delaware Canal, and from Mary- land. The author contends that the green sands are pre-Tertiary in age and should be correlated with the Lower Chalk of England. Eaton had claimed that these beds were of Tertiary age. 1832. Conrap, T. A. Fossil shells of the Tertiary Formations of North America illustrated by figures drawn on Stone from Nature. Vol. i, pts. 1 and 2, 28 pp. Phila., 1832. Republished by G. D. Harris, Washington, 1893. Cardita planicosta is reported from Middle Tertiary near Piscataway. The stratum containing the fossil is supposed to be the equivalent of the London clay and calcaire grossier. A gigantic Cucullaea and Ostrea compressirostia are reported in similar material at Fort Washington. 1833. Fincu, J. Travels in the United States of America and Canada. 8vo, 455 pp. London, 1833. The author speaks of the red sandstones at Bladensburg used for founda- tions and of the red soil exposed in ravines in the city of Washington. He describes the greensand mar] at Fort Washington together with its contained fossils——Pecten, Cardiwm, Arca, Ostrea, Ichthyosaurus, Crodiles, and Sharks. He says that the marl is used as manure. Lea, Isaac. Contributions to Geology. 8vo, 237 Phila., 1833. The Tertiary deposits of Claiborne, Alabama, are fully described and are correlated with the Fort Washington beds. pp-, 6 plates. MARYLAND GEOLOGICAL SURVEY 30 Conrap, T. A. Observations on the Tertiary and more recent for- mations of a portion of the Southern States. Jour. Acad. Nat. Sci., Phila., vol. vii, 1834, pp. 116-129. The author uses the term “Hocene” in describing the deposits at Fort Washington. He states that the Hocene strata extend to the southwest from Maryland, but considers the deposits of Maryland as younger than those of Claiborne, Ala., and probably to be correlated with the miocene of Europe. Ducatet, J. T., and Arexanper, J. H. Report on the Projected Survey of the State of Maryland, pursuant to a resolution of the Gen- eral Assembly. S8vo, 39 pp. Annapolis, 1834. Map. Several editions. Amer. Jour. Sci., vol. xxvii, 1835, pp. 1-39. Shell marl deposits are reported to occur at Indian Point, on the western branch of the Patuxent River, at “Upper Marlborough,” and at Fort Wash- ington. The deposits at the latter place are said to have no practical value. Copperas ore (iron pyrites) is said to occur at Oxen Creek and bog iron ore in the neighborhood of Queen Anne (Hardesty); while carbonate of iron ore is described from “Snowden’s mine bank, situated on the east side of the Washington Turnpike, near the twenty-first mile stone and about half a mile from the road. ‘The ore was formerly extracted from this bank in large quantities, as is evident from the excavation.” Hartan, Rictrarp. Critical Notices of Various Organic Remains Hitherto Discovered in North America. (Read May 21, 1834.) Trans. Geol. Soc. Pa., vol. I, pt. L. 1834, pp. 46-112. The author states that specimens of Hgnus callabus were “found in exca- vating for the Chesapeake and Ohio Canal near Georgetown, D. C., not far from the Potomac River.” (p. 61.) Morton, 8. G. Synopsis of the Organic Remains of the Creta- ceous Group of the United States. To which is added an appendix containing a tabular view of the tertiary fossils hitherto discovered in North America. 8vo, 88 pp. Phila., 1834. (Abst.) Amer.Jour. Sci., vol. xxvii, 1835, pp. 377-381. He states that the “Ferruginous Sand” is present at Fort Washington, where it contains erogyrd. THE PHYSICAL FEATURES OF PRINCE GEORGE'S COUNTY (Su) DP 1835. Conran, T. A. Observations on the Eocene Deposits of the United States. Fossil Shells of the Tertiary Formations of North America, vol. i, No. 3, pp. 29-36. Phila., 1835. Republish by G. D. Harris, Washington, 1893. Describes the distribution of the Eocene of the county mentioning its occurrence at Fort Washington, Piscataway and Upper Marlborough. The latter place the author believed was the northern limit of the Eocene. Conran, T. A. Observations on the Tertiary Strata of the Atlantic Coast. Amer. Jour. Sci., vol. xxviii, pp. 104-111, 280-282. He considers the miocene absent in this region, the Older Phiocene resting directly on the Hocene. The beds containing Perna mavillata are referred to the Older Phiocene, and the St. Mary’s river beds to the Medial Phiocene. Conran, T. A. Observations on a portion of the Atlantic Tertiary Region. Trans. Geol. Soc. Penn., vol. I, 1835, pp. 335-341, pl. 18. Deposits at Piscataway and Upper Marlborough are described. At the former locality the following new forms are described: Panopea elongata, modiola cretacea, and Turritella humerosa. Ducatet, J. T. and ALrexanper, J. H. Report on the New Map of Maryland, 1834. Annapolis, 1835(?%). 8vo, 59-+1 pp. Two maps and one folded table. Contains Engineer’s and Geologist’s reports, which were also issued separately. Md. House of Delegates, Dec. Sess., 1834. In the report of the engineer, Mr. Alexander, a very good account is given of the way in which Piscataway Creek is being filled up with silt. It is recommended that canals be dug along both sides of the stream to receive the wash from the hills and empty it into the Potomac rather than per- mitting it to fill up Piscataway Creek, an expedient perhaps, however, more costly than useful. In the geologist’s report the Eocene deposits at Fort Washington, Pisca- taway, and Upper Marlborough are described while the value of the shell marls of the region for economic purposes is discussed. He says that no Miocene has yet been recognized in the State. The physiography of the region is described and mention is made of the gravel cap at Fort Washing- ton, though it is not separated from the Hocene. The map contains many notes in regard to the geology of the region bordering the Potomac River. MARYLAND GEOLOGICAL SURVEY 39 Martin, Joseru. A Comprehensive Description of Virginia, and the District of Columbia. Richmond, 1835( 7). He describes the separation of the “Primitive” and “Alluvial” formations in the District. In the former gneiss abounds and is succeeded by “amphi- bolie” rock. Morton, 8. G. Additional Observations (to Synopsis). Svo, 4 pp. Phila., June, 1835. Gryphaea vomer is added to the Eocene forms obtained at Upper Marl- borough and Piscataway. 1836. Ducaret, J. T. and Arexanprr, J. H. Report on the New Map of Maryland, 1835. 8vo, 84 pp. Maps. Annapolis, 1836. Md. Pub. Doe., Dec. Sess., 1835. Engineer’s Report, pp. 1-34, Geologist’s Report, pp. 35-84. Both reports also published separately. In the engineer’s report a good description of Piscataway Creek is given and the changes which are taking place in it. A plan for a canal extending up the creek to the town of Piscataway is discussed. Dueatel reports the presence of a micaceous black sand in the deep ravines bordering the Mattaponi in the vicinity of Nottingham. It is said to form a part of the “ferruginous sand formation” which he believes to belong to the Secondary Analyses of micaceous black sand, green sand period (1-83) and shell marl (p. 82) are given. Fraruerstonuaucn, G. W. Report of a Geological Reconnais- ) fo) sance made in 1835 from the seat of government by way of Green Bay and the Wisconsin Territory on the Coteau du Prairie, ax elevated ridge dividing the Missouri from the St. Peters river. 169 pp., 4 pls., Washington, 1836. Describes the decomposed gneiss above Georgetown and along Rock Creek. He says that the gneiss underlies Washington and Georgetown dipping to the southeast. llshail Ducatet, J. T. and Atexanper, J. H. Report on the New Map of Maryland, 1836. 8vo, 104 pp., 5 maps. Annapolis, 1837. Md. House of Delegates, Dec. Sess., 1836. Geologist’s Report, pp. 1-60, Engineer’s Report, pp. 61-104. Dueatel describes shell and greensand depcsits of Eocene and Miocene age from many places in the county and discusses their economic value as fertilizers. He mentions the pink clay (Marlboro) occurring with green- sand north of Upper Marlborough. 40 THE PHYSICAL FEATURES OF PRINCE GEORGE'S COUNTY Ducatet, J. T. Outline of the Physical Geography of Maryland, embracing its prominent Geological Features. Trans. Md. Acad. Sci. and Lit., Vol. I, Pt. I, 1837, pp. 24-54, with map. A general description of the physiography and geology of the entire State is given with many details of local features. It is a general summary of information previously published in various places. Mention is made of the covering of boulders and coarse gravel near the inner edge of the Secondary (Cretaceous) rocks while farther out the sands and clays of the Secondary and Tertiary formations are uncovered. 1838. Conrap, T. A. Fossils of the Medial Tertiary of the United States. No. 1, 1838. [Description on cover 1839 & ’40.] 32 pp. Plates I-X VIL. Republished by William H. Dall, Washington, 1893. A general description of the distribution and characteristics of the Miocene of the Atlantic Coastal Plain is given. The Miocene is called the Medial Tertiary or Older Pliocene and the Eocene is called Lower Tertiary. The Medial Tertiary is said to overlie the Lower Tertiary at Upper Marlboro and is found to the south of a line drawn from Annapolis to Fort Washington. 1839. Conran, T. A. Notes on American Geology. Observations on Characteristic Fossils, and upon a fall of Temperature in different Geological Eypochs. Amer. Jour. Sci., vol. xxxv, 1839, pp. 237-251. “At Upper Marlborough and Piscataway, in Maryland, a deposit of the Eocene period occurs, composed of the detritus of green sand, a material originating in the cretaceous epoch. One fossil of the latter formation, (Gryphaea vomer, [ostrea lateralis, Wilson|) is not uncommon among the Eocene fossils. This is at the same time the lightest and most indestructible of the cretaceous shells, and therefore the one most likely to be carried unbroken with the detritus of the green sand.” 1842. Conran, T. A. Descriptions of New Tertiary Fossils. Second Bull. Proc. Nat. Inst. Prom. Sci., 1842, pp. 192-194, 2 pls. Pholadomya marylandica is described from Piscataway. MARYLAND GEOLOGICAL SURVEY 4] Conran, T. A. Observations on a portion of the Atlantic Tertiary Region, with a description of new species of organic remains. Second Bull. Proc. Nat. Inst. Prom. Sci., 1842, pp. 171-192. The deposits of the Eocene at Piscataway, Upper Marlboro, and Fort Washington are described and their characteristic fossils mentioned. They are correlated with the Bognor rocks of Great Britain and the Claiborne beds of Alabama. The Miocene and Eocene are said to not be connected by a single fossil common to both periods while three fornia found in the Upper Secondary are found in the Eocene. 18438. Dvucate, Juztivs T. Physical History of Maryland. Abstract Proc. Amer. Phil. Soe., vol. iii, 1843, pp. 157-158. “The Eastern Shore is shown to consist of something more than arid sand- hills and pestilential marshes; and the Western Shore not to depend exclu- sively upon the rich valleys of 'rederick and Hagerstown for its supplies.” 1844. B(attry), J. W. Account of some New Infusorial Forms discov- ered in the Fossil Infusoria from Petersburg, Va., and Piscataway, Md. Amer. Jour. Sci., vol. xlvi, 1844, pp. 137-141, pl. iii. Ten species are described and over 30 figures given. EnrENBERG, C. G. Ueber zwei neue Lager von Gebirgsmassen aus Infusorien als Meeres-Absatz in Nord Amerika und eine Ver- gleichung derselben mit dem organischen Kreide-Gebilden in Europa und Afrika. Bericht. k. p. akad. Wiss. Berlin, 1844, pp. 57-97. Reviewed Amer. Jour. Sci., vol. xlviii, 1845, pp. 201-204. Sixty-eight species of infusoria are enumerated from Piscataway including a great many new forms. Comparisons are made with the diatoms occurring at Richmond and Petersburg, Virginia, and in Europe and Africa. Rtocers, H. D. Address delivered at the Meeting of the Associa- tion of American Geologists and Naturalists. Amer. Jour. Sci., vol. xlvii, 1844, pp. 137-160, 247-278. The article consists of a resumé of the geological work done up to that time in the entire United States. Reference is made to Conrad’s work on the Eocene fossils found at Upper Marlborough and Bailey’s investigations on the infusoria near Piscataway. 49 THE PHYSICAL FEATURES OF PRINCE GEORGES COUNTY tocers, Wu. B. [Tertiary Infusorial Formation of Maryland. | Amer. Jour. Sci., 2nd ser., vol. xlvi, 1844, pp. 141-142. A short description of the geographical extent of the infusorial stratum is given. He places the deposits near the base of the “Meiocene.”’ Names of infusoria identified by Professor Bailey are given. 1845. Batrey, J. W. Notice of some New Localities of Infusoria, Ios- sil and Recent. Amer. Jour. Sci., vol. xlviii, 1845, pp. 321-343, pl. iv. Gives lists of forms found in EKocene marl of Fort Washington and in Miocene deposits near Piscataway. Casts of Polythalamia are reported from Fort Washington. 1846. Conrap, T. A. Observations on the Eocene Formation of the United States, with descriptions of species of shells, ete., occurring Im Lt Amer. Jour. Sci., 2nd ser., vol. i, 1846, pp. 209-221, 395-405, pls. i, ii, iii, iv. Following fcssils are described from Piscataway: Pholas petrosa, Phola- domya Marylandica, Panopaea intermedia, Crassatella alaeformis, and Crassatella palmula from Upper Marlborough. 1847. Conran, T. A. Observations on the Eocene Formation and deserip- tion of one hundred and five new fossils of that period from the vicinity of Vicksburg, Mississippi. With appendix. Proc. Acad. Nat. Sci. Phila., vol. iii, 1847, pp. 280-299. The writer regards the Hocene deposits of Prince George’s County as Lower Hocene and the Claiborne, Charleston, and Vicksburg beds as Upper Hocene. 1848. Conran, T. A. Observations on the Eocene Formation and deserip- tions of one hundred and five new fossils of that period from the vicinity of Vicksburg, Mississippi, with an appendix. [| Description of New Eocene Fossils in the cabinet of Lardner Vanuxem. | Jour. Acad. Nat. Sci. Phila., 2nd ser., vol. i, 1849, pp. 111-134, pls. 11-14. The Fort Washington, Piscataway, and Upper Marlborough Hocene deposits referred to the Lower Kocene are correlated with the Alabama deposits at Claiborne and St. Stephens because of the presence of Ostrea sellaeformis. Mention is made otf several Eocene species from this county. MARYLAND GEOLOGICAL SURVEY 43 1849. Bartry, J. W. New Localities of Infusoria in the Tertiary of Maryland. Amer. Jour. Sci., 2nd ser., vol. vii, 1849, p. 437. Piscataway is mentioned as the most northerly point where infusoria have been found in the Miocene. ODS. Desor, E. Post Pliocene of the Southern States and its relation to the Laurentian of the North and the Deposits of the Valley of the Mississippi. Amer. Jour. Sci., 2nd ser., vol. xiv, 1852, pp. 49-59. The boulders in the vicinity of Washington are said to have been brought to their present position by floating ice bergs carried by the Potomac river from beyond the Blue Ridge. A suggested correlation of the superficial deposits of Maryland with the Laurentian of Canada and the post-Pliocene of South Carolina is discussed. Fisurer, R. S. Gazetteer of the State of Maryland compiled from the returns of the Seventh Census of the United States. New York and Baltimore, 1852, 8vo, 122 pp. Contains numerous descriptions of the geography and geology of different portions of the State. The diatomaceous earth (called “siliceous clay”) bed at Piscataway is briefly described. Hiearns, James. The Second Report of James Higgins, M. D., State Agricultural Chemist, to the House of Delegates of Maryland. 8vo, 118 pp. Annapolis, 1852. Md. House of Delegates, Jan. Sess., 1852. S8vo, 126 pp. Large deposits of phosphate of iron are reported to occur on the farm of Mr. James Mulliken and it has also been noticed in several other places in that neighborhood. ‘When pure it contains about 28 per cent. of phosphoric acid. The average of six analyses of the above deposit, taken and made at different times, shows 16 per cent. of phosphoric acid.” The soils and marls of the county are discussed and many analyses given. Jounson, Atexanper S. Notice of some undescribed Infusorial Shells. Amer. Jour. Sci., 2nd ser., vol. xiii, 1852, p. 33. The infusoria Asterodiscus nonarius and Asterolampra septenaria from Piscataway are described. 44. THE PHYSICAL FEATURES OF PRINCE GEORGES COUNTY 1853. Marcou, Jutes. A Geological Map of the United States and the British Provinces of North America, with an explanatory text. (ete. ) 8vo. Boston, 1853. Shows the general distribution of the Coastal Plain strata. No Cretaceous represented on the Western Shore of Chesapeake Bay. 1855. Marcou, J. Resumé explicatif d’un carte géologique des Etats- Unis et des provinces anglaises de ’ Amérique. Bull. Soc. Geol. France, 2nd ser., tome xii, 1855, pp. 813-936. Colored geological map. Mention is made of the occurrence of Eocene at Fort Washington and brief statements concerning the Cretaceous and Tertiary deposits of the entire State. 1856. Batrey, J. W. On the Origin of Greensand, and its formation in the oceans of the present epoch. Amer. Jour. Sci., 2nd ser., vol. xxii, 1856, pp. 280-284. Proc. Bost. Soc. Nat. Hist., vol. v, pp. 364-368. Reference is made to the abundant casts of Polythalamia in the Eocene greensand of Fort Washington. Hnrensere, C. G. Zur Mikrogeologie. Two vols. and atlas, royal folio, 41 pls. Leipzig, 1854-56. Mention forms of protozoa from Fort Washington. 1859. Jounston, Curisropurr. Notes on Odontology. Amer. Jour. Dental Sci., Phila., n. s. vol. ix, No. 3, 1859, pp. 337-343. A description is given of Astrodon (afterwards called Astrodon jolurstoni) from Bladensburg. 1860. Tyson, Purure T. First Report of Philip T. Tyson, State Agri- cultural Chemist, to the House of Delegates of Maryland, January, MARYLAND GEOLOGICAL SURVEY 45 1860. 8vo, 145 pp. Maps. Appendix. Mineral Resources of Mary- land, 20 pp. Annapolis, 1860. The report is accompanied by a colored geological map which shows the distribution of the various formations. The Coastal Plain formations repre- sented are the Cretaceous, Tertiary, and Post Tertiary, while the iron-ore clays of the Cretaceous are separated from the other Cretaceous deposits. A brief description is given of each formation. The green sand and shell marl deposits are mentioned. The Cretaceous clays of the county are briefly described. The carbonate of iron ores of the Cretaceous are described and also deposits of iron pyrites near Oxon Creek. 1861. Jounston, Curisropuer. Upon a Diatomaceous Earth from Nottingham, Calvert Co., Maryland. Proc. Amer. Assoc. Adv. Sci., vol. xiv, 1860, pp. 159-161. The writer gives reasons for believing that the “Bermuda earth’ must have come from Nottingham. A brief description of the deposit is given. ‘Tyson is quoted as being unable to decide whether the bed belongs to the Upper Eocene or the Lower Miocene. Norman, Grorer. On some Undeseribed Species of Diatomaceae. (Read Nov. 14, 1860.) Trans. Micros. Soc., London, n. s. vol. ix, 1861, pp. 5-9. Describes and figures Aulacodiscus sollitianus (n. sp.) from Nottingham, Md. 1862. Tyson, Puitire T. Second Report of Philip T. Tyson, State Agri- cultural Chemist, to the House of Delegates of Maryland, January, 1862. 8vo, 92 pp. Annapolis, 1862. Among the mineral resources described are the following from this county: Carbonate of iron ores supposed to belong to the odlitic period, a large de- posit of iron pyrites at Oxen Creek, five miles south of Washington, clays, and tripoli near Nottingham. 1864. Conrap, T. A. Notes on Shells, with description of new fossil Genera and Species. Proc. Acad. Nat. Sci., Phila., vol. xvi, 1864, pp. 211-214. Dosiniopsis meekii is reported from a locality six miles east of Washing- ton where it is said to occur “abundantly in a dark grey quartzose sand.” It is said to characterize the oldest portion of the American Eocene which has yet been observed. p. 213. 46 THE PHYSICAL FEATURES OF PRINCE GEORGE'S COUNTY Conrap, T. A. Observations on the Eocene Lignite Formation of the United States. Proc. Acad. Nat. Sci., Phila. vol. xvii, 1865, pp. 70-73. (Abst). Amer. Jour. Sci., 2d ser., vol. xi, 1865, pp. 265-268. The lignitic beds now included in the Magothy formation are considered to constitute the basal beds of the Eocene, and are correlated with the London clay of Europe. ‘‘They reveal a singular state of the globe at the commencement of the Tertiary period, presenting a vast level region covered by a dense forest, in which palms and oaks grew side by side, interspersed with lakes and rivers, and long shallow bays of salt water penetrating to the interior of the continents. This state of the globe was exhibited in Hurope and America at the same time.” p. 268. Conran, T. A. Catalogue of the Eocene and Oligocene Testaeca of the United States. Amer. Jour. Conch., vol. i, 1865, pp. 1-35. Several species of Eocene fossils from Upper Marlboro and Piscataway Creek are included in the lists. Leipy, Josrepn. Cretaceous Reptiles of the United States. Smith. Contrib. to Knowledge, No. 192, vol. xiv, 1865, 185 pp., 20 pls. Teeth of Astrodon johnstoni found in an iron ore bed near Bladensburg, are described and figured. 1866. Conrap, T. A. Check List of the Invertebrate Fossils of North America (Eocene and Oligocene). Smith. Misc. Coll., vol. vii, 1866, 41 pp. Lists of all Eocene and Ohjocene fossils known at that time are given but without exact locality references. The Eocene deposits near Washington, at Piscataway, and at Upper Marlboro are referred to the Lower Hocene. TSG Hicerns, James. A Suecinct Exposition of the Industrial Re- sources and Agricultural Advantages of the State of Maryland, 8vo, 1097 niet: Md. House of Delegates, Jan. Sess.,-1867. [DD.] Md. Sen. Doc., Jan. Sess., 1867. [U.] Contains a description of the soils and physiographic features of each of the counties of the State. MARYLAND GEOLOGICAL SURVEY 47 1868. Corr, E. D. (On the discovery of the fresh-water origin of cer- tain deposits of sand and clays in west New Jersey. ) Proc. Acad. Nat. Sci., Phila., vol. xx, 1868, pp. 157-158. A brief concise description of the distribution and character of the de- posits, now designated the Potomac Group, is given and Tyson is quoted as believing that they are of Jurassic rather than Cretaceous. “The whole formation indicates the existence of an extended body of fresh water, having a direction and outline similar to that in which were deposited the red sand- stones and shales of the Triassic belt, which extends parallel to its north- west margin throughout the States in which it occurs.” (p. 157.) 1875. Jounston, Curistorier. About the Rediscovery of the “Ber- muda Tripolh” near Nottingham, on the Patuxent, Prince George's County, Md. Proc. Boston Soc. Nat. Hist., vol. xvii, 1875, pp. 127-129. The writer describes the circumstances connected with the discovery that the so-called “Bermuda tripoli” never came from Bermuda, but from the vicinity of Nottingham, Prince George’s county. Suriivant, J. [Letter to Professor Christopher Johnston on Ber- muda Tripoli in Maryland. | Proc. Boston Soc. Nat. Hist., vol. xvii, 1875, pp. 422-423. The writer expresses his belief that the so-called “Bermuda Tripoli” did not come from Bermuda or Bermuda Hundreds, Virginia, but from Notting- ham, Md. isn Fonrainn, W. M. Notes on the Mesozoic of Virginia. Amer. Jour. Sci., 3d ser., vol. xvii, 1879, pp. 25-39, 151-157, 229-239. Brief descriptions are given of the iron ore clays of the Potomac group in the belt extending from Washington to Baltimore. He speaks of the Potsdam and Azoic boulders about Washington and between there and Baltimore which he thinks were brought down during the Jurassic by icebergs and glaciers. 48 THE PHYSICAL FEATURES OF PRINCE GEORGE'S COUNTY 1880. Herpriy, Aneuto. On the Stratigraphical Evidence Afforded Ly the Tertiary Fossils of the Peninsula of Maryland. Proc. Acad. Nat. Sci., Phila., vol. xxxii, 1880, pp. 20-33. After a careful examination of the fossils found along the Patuxent, Chop- tank and St. Mary’s rivers and the Calvert Cliffs, the author proposes the separation of the Miocene into the Older and Newer periods. The beds at Fair Haven are typical Older Miocene and the St. Mary’s lower Patuxent, and Choptank river beds belong to the Newer Miocene. 1881. Heirpin, Anceto. Note on the Approximate Position of the Eocene Deposits of Maryland. Proc. Acad. Nat. Sci., Phila., vol. xxxiii, 1881, pp. 444-447. The Eocene of Maryland, consisting of “the Piscataway sands below, and the Marlborough rock above” is supposed to represent “a horizon nearly equal to that of the Thanet sands of England and the Bracheux sands of the Paris basin, or of the British Bognor rock (= London Clay)” are also correlated with the Alabama deposits. They are supposed to be equivalent to the beds “near the base of the ‘Buhrstone’ or possibly even lower.” (p. 447.) 1882. Heriprin, Anceio. On the relative ages and classification of the Post-Eocene Tertiary Deposits of the Atlantic Slope. Proc. Acad. Nat. Sci., Phila., vol. xxxiv, 1882, pp. 150-186. (Abst.) Amer. Jour. Sci., 3d ser., vol. xxiv, 1882, pp. 228-229. Amer. Nat., vol. xvii, 1883, p. 308. From a comparison of faunas the Eocene deposits of Maryland are cor- related with the Eo-Ligniter of Alabama, and the Miocene beds of the State are grouped in a division called the Marylandian which is supposed to be older than any other Miocene beds of this country, with the possible exception of the basal Miocene beds of Virginia which may be contemporaneous. 1885. Smock, J. C. The Useful Minerals of the United States. Min. Resources of the U. 8., 1882. Washington, 1883, pp. 690-693. The following minerals are reported from this county: Limonite from Snowden’s Bank, Greensand and shell marls, Lignite in clay, Pyrite from Oxen Creck, Siderite, Tripolite from near Nottingham. MARYLAND GEOLOGICAL SURVEY 49 Unter, P. R. Geology of the Surface Features of the Baltimore Area. Johns Hopkins Univ. Cire. No. 21, vol. 11, 1883, pp. 52-53. (Abst) Science, vol. 1, 1883, pp. 75-76, 277. The hard resistant sandstones that outcrop near Collington (Collingwood as given in the article) are referred to the Wealden and are said to represent the remnants of a widespread deposit. The conditions that prevailed during the Jurassic, Cretaceous, and Pleistocene periods are briefly described. Witsur, F. A. Marls. Mineral Resources U. 8., 1882, Wash- ington, 1883, p. 522. Greensand marls of Cretaceous age are said to occur in Kent, Cecil and Prince George’s counties. 1884. Hertprin, Ancrto. The Tertiary Geology of the Eastern and Southern United States. Jour. Phila. Acad. Nat. Sci., vol. ix, pt. i, pp. 115-154, map, 1884. The distribution of the Tertiary strata of the State is given approximately. The Eocene is correlated with the base of the Buhrstone or the Eo-lignitic of Alabama and with the London Clay. The Miocene of the State is divided into two formations, the older or Marylandian which is regarded ag possibly Oligocene in age, and the newer or Virginian. The former is exposed in Anne Arundel, Calvert, and Charles counties and the latter at Easton, on the Choptank River, and in St. Mary’s County. Hettprin, Anceto. Contributions to the Tertiary Geology and Paleontology of the United States. 4to 117 pp., 1 map. Phila., 1884. Contains a number of articles all but one of which were previously pub- lished in the Proceedings or Journal of the Phila. Academy of Natural Sciences. Some of these articles are listed on preceding pages. Merrity, Gro. P. Preliminary note on the Crystalline Schists of the District of Columbia. Proc. U. S. Nat. Mus., vol. vi, 1884, pp. 159-161. (Abst.) Science., vol. ii, 1883, pp. 829-830. A brief description of some of the erystullus rocks near Washington. Merrity, Gro. P. (Notes on the Building Stones of Washington, D. C.) Tenth Census, vol. x. Washington, 1884. p. 857-361. Some brief statements descriptive of the local building stones are made though the greater portion of the article consists of a discussion of the building stones used in the building operations of Washington, most of which are brought from a distance. 50 THE PHYSICAL FEATURES OF PRINCE GEORGES COUNTY 1885. Cuester, Frepertck D. The Gravels of the Southern Delaware Peninsula. Amer. Jour. Sci., 3d ser., vol. xxix, 1885, pp. 36-44. The high level gravels about Washington are said to be contemporaneous with the high level or Bryn Mawr gravels of Delaware and southeastern Pennsylvania which are questionably referred to the Cretaceous. McGrn, W J. The Geology of the District. The Evening Star, Washington July 11, 1885. In the article the author states that “but three essentially distinct forma- tions occur within the District of Columbia. These are: (1) the Washington gneiss, which includes the gneisses, mica schists, amphibolites (massive green stones) and related crystalline rocks so well exposed along the Potomac above Georgetown; (2) the Potomac formation, comprising the laminated clays, sands and gravels spread over the highest lands of the District, and (3) the Columbia formation, made up of the brick clays, sands and gravels prevailing throughout the bluff-bound amphitheatre in which Washington is located.” The Potomac formation is said to be of Lower Cretaceous age and to have been deposited in shallow water near the shore when the ocean stood 600 feet above its present level. The Columbia formation is said to be “apparently a delta deposit laid down in the broad estuary of the Potomac that existed when the waters of the ocean rose more than 100 feet above present tide level.” The various terraces about Washington are als» described. Roxsinson, T. The Strata Exposed in the East Shaft of the Water Works Extension. Abst. Bull. Phil. Soe., Washington, vol. vii, 1885, pp. 69-71. The section shows a thickness of about 144 feet of Columbia and Potomac deposits representing 23 different strata. The Piedmont crystallines were penetrated to the depth of 43 feet. Spencer, J. W. Occurrence of Boulders of Decomposition at Washington, D. C., and elsewhere. Amer. Nat., vol. xix, 1885, pp. 163-165. Briefly describes decomposition boulders of gneiss along the Potomac River near Georgetown. MARYLAND GEOLOGICAL SURVEY Eyal 1886. a | Benton, Epwarp R. Notes on the samples of iron ore collected in Maryland. Tenth Census. vol. xv, Mining Industries of the U. S. Washington, 1886, pp. 245-260. Several sections of the strata exposed in iron mines near Beltsville, Branch- ville, and Muirkirk are given, together with analyses of the ores. McGer, W J. Geological Formations Underlying Washington and Vicinity. Rep’t Health Officer of the District of Columbia for the year ending June 30, 1885, pp. 19-21, 23-25. Abst. Amer. Jour. Sci., 3d ser., vol. xxxi, 1886, pp. 473-4. Speaks of the Columbia formation about Washington appearing “to repre- sent a subaqueous delta of the Potomac river, formed when the sea rose far above its present level and fashioned the marine terraces exhibited in the bluffs. Its absence above sea level east of the Eastern Branch may be attributed to a dislocation trending parallel to the Appalachians and the Atlantic coast.”” The Potomac formation is also briefly described. Prate, A. C. Lists and Analyses of the Mineral Springs of the United States. Bull. U. S. Geol. Survey, No. 32, 1886, pp. 51-53. The saline and chalybeate Spa Springs at Bladensburg are included in the list of Maryland springs. Pumre try, R. Geological and Geographical Distribution of the Tron Ores of the United States. Tenth Census, vol. xv, Mining Industries of the U. S. Washington, 1886, pp. 3-36. Brief reference is made (p. 16) to the Potomac iron ores between Balti- more and Washington. 1887. McGer, W J. Ovibos eavifrons from the Loess of Iowa. Amer. Jour. Sci., 3d ser., vol. xxxiv, 1887, pp. 217-220. “During the earlier epoch of Quaternary cold, the middle Atlantic slope was submerged to a depth of over three hundred feet, and its rivers built deltas at their embouchures into the expanded Atlantic along the inland margin of the Coastal Plain of today.” The ice-borne boulders brought down by the Susquehanna at that time are said to have been fifty times as large as those carried at the present time and those brought by the Patapsco and Potomac twenty times the size of those of today. 52 THE PHYSICAL FEATURES OF PRINCE GEORGES COUNTY Wuire, I. C. Rounded Boulders at High Altitudes along some Appalachian Rivers. Amer. Jour. Sci., 3d ser., vol. xxxiv, 1887, pp. 374-381. “Submergence, with re-elevation in comparatively recent times, will then give a sufficient explanation for the existence of the elevated bowlder deposits in the vicinity of Washington, D. C., Richmond, Philadelphia, and possibly as far west as Cumberland.” 1888. Crark, Wn. B. On three Geological Excursions made during the months of October and November, 1887, into the southern counties of Maryland. Johns Hopkins Univ. Cire., No. 63, vol. vii, 1888, pp. 65-67. The following fossils are reported from the Hocene at Fort Washington: Cucullaea gigantea, Conrad; Crassatella, sp.; Cytherea, sp.; Cytherea (Dosini- opsis) Meekii, Conrad; Jurritella Mortons, Conrad; Sharks teeth at Upper Marlboro a green and yellow variegated marl containing casts or fragments of several genera of mollusca is said to be well exposed. Kwnowtton, F. H. The Fossil Lignites of the Potomac Formation. Proc. Amer. Assoc. Adv. Sci., vol. xxxvii, 1888, pp. 206-208. The characteristics and mode of occurrence of the lignitized and silicified plant remains of the Potomac formation are briefly described. Marsu, O. C. Notice of a New Genus of Sauropoda and other new Dinosaurs from the Potomac Formation. Amer. Jour. Sci., 3d ser., vol. xxxv, 1888, pp. 89-94, figs. 1-9. The remains of three new species of herbivorous and two new species of carnivorous dinosaurs obtained from the Potomac strata of Prince George’s county are described and figured. The author states that the fossils are “apparently of Upper Jurassic age, but quite distinct from any hitherto discovered in this country.” McGrxr, W J. The Geology of the Head of Chesapeake Bay. 7th An. Report U. S. Geol. Surv. Washington, 1888, pp. 537-646. Abst. Amer. Geol., vol. i, 1887, pp. 113-115. Contains a general discussion of the Potomac and Columbia deposits. Eyidence is given to prove recent displacements in the vicinity of the “fall line.’ At Washington the total displacement is from 75 to 100 feet. MARYLAND GEOLOGICAL SURVEY 53 McGur, W J. Three Formations of the Middle Atlantic Slope. Amer. Jour. Sci., 3d ser., vol. xxxv, 1888, pp. 120-143, 328-331, 367-388, 448- 466, plate ii. The three formations discussed are the Potomac (now divided into four formations), the Appomattox (Lafayette) and the Columbia (now divided into three formations.) These are described in far greater detail than had ever been done before and the conclusions reached vary but little from the views held at the present time. McGee, W J. The Columbia Formation. Proc. Amer. Assoc. Adv. Sci., vol. xxxvi, 1888, pp. 221-222. The Columbia formation overlying unconformably the Cretaceous and Tertiary deposits of the Atlantic Coastal Plain is said to consist of series of deltas and terraced littoral deposits. It is said to pass under the terminal moraine to the northward. The Columbia materials are supposed to have been laid down during a period of glaciation long preceding the glacial epoch during which time the terminal moraine was formed. Marcov, Jutes. American Geological Classification and Nomen- clature. 75 pp. Cambridge, Mass., 1888. The writer mentions a specimen of Eycad found in association with pieces of petrified wood and broken bones “on the farm of Dr. Jenkins, one mile south of the Baltimore and Washington railroad, sixteen miles from Wash- ington, Prince George’s county, Maryland.’ He correlates the deposit in which the specimens were found with the Purbeck formation of England. Unter, P. R. The Albirupean Formation and its nearest relatives in Maryland. Proc. Amer. Phil. Soc., vol. xxv, 1888, pp. 42-53. Discussion by H. Carvill Lewis and A. Heilprin (pp. 53-54.) In this article the writer proposed the name of ‘“‘Baltimorean” for the basal Potomac deposits and “Albirupean” for the sands that overlie the basal beds and which are firmly indurated in several places in the State. One of the places where the sandstone is described is in ‘the vicinity of the fork of the Great Patuxent river, in Prince George’s county.” The pre-Tertiary deposits of the Coastal Plain are said to consist of the two formations named above and the marine greensands. In the discussion Professors Lewis and Heilprin disagreed with Dr. Uhler as they claimed he had included some Paleozoic quartzites with the mesozoic sandstones in the albirupean formation. Unter, P. R. Observations on the Eocene Tertiary and its Cre- taceous Associations in the State of Maryland. Trans. Md. Acad. Sci., vol. i, 1888, pp. 11-32. Many details concerning the distribution, lithologic characteristics, and fossil content of the Eocene and Cretaceous deposits of this county are given. 54 THE PHYSICAL FEATURES OF PRINCE GEORGES COUNTY Warp, Lester F. Evidence of Fossil Plants as to the Age of the Potomac Formation. Amer. Jour. Sci., 3d ser., vol. xxxvi, 1888, pp. 119-131. From an examination of the fossil plants of the Potomac formation the author states that “the Potomac flora, viewed in all its bearings, cannot be said positively to negative the reference of the formation to the Jurassic upon the evidence of the plants alone.” 1889. 3ryvAn, O. N. The Cretaceous Formation of Southwestern Mary- land. Amer. Nat., vol. xxiii, 1889, pp. 713-714. The Hocene and Cretaceous deposits in the vicinity of Fort Washington and Piscataway are briefly described and are said to be underlain by a lower formation which is thought to be of Jurassic age. Crarx, Wn. B. Discovery of Fossil-Bearing Cretaceous Strata in Anne Arundel and Prince George Counties, Maryland. Johns Hopkins Univ. Cire., No. 69, vol. viii, 1889, pp. 20-21. Fossiliferous Cretaceous strata are reported to occur in tributaries of the Patuxent River due east of Collington and at Fort Washington. Lists of fossils found at these places are given. This is the first mention of fossilif- erous Cretaceous strata west of Chesapeake Bay. The beds are said to lie nearly horizontal. Fontaine, W. M. Potomac or Younger Mesozoie Flora. Monograph U. S. Geol. Surv., vol. 15, Washington, 1889, 377 pp., 180 pls. Contains a description of the Potomac deposits and the plant remains found in them. Many of the fossils were obtained in Prince George’s county at Fort Washington, Beltsville and Contee and in the District of Columbia. Knowrron, F. H. Fossil Wood and Lignites of the Potomac Formation. (Read before Amer. Assoc. Adv. Sci., 1888.) Amer. Geol., vol. iii, 1889, pp. 99-106. A brief description is given of the Potomac formation. Good exposures containing lignite and silicified wood are said to occur at Fort Washington, in the cities of Baltimore and Washington and at several points in Virginia. Detailed descriptions of the silicified wood and lignite are given. Know.ton, F. H. Fossil Wood and Lignite of the Potomac For- mation. Bull. U. S. Geol. Surv. No. 56, Washington, 1889. Contains a brief discussion of the distribution of the Potomac deposits and a detailed description of some species of fossil wood found in them. Or e MARYLAND GEOLOGICAL SURVEY Marsun, O. C. Geologic and Paleontologic Investigations in Mary- land. 9th An. Rep’t. U. S. Geol. Surv., 1887-88, Washington, 1889, pp. 114-115. The statement is made that on the evidence obtained from fossils the Potomac formation has been “proved conclusively” to be “of Upper Jurassic age’ and that it “contains a rich and varied fauna.” McGrr, W J. The Geological Antecedents of Man in the Potomac Valley. Amer. Anth., vol. ii, 1889, pp. 227-234. The conditions prevailing during the times that the Potomac and Columbia deposits were being formed are described. Unter, P. R. Additions to Observations on the Cretaceous anil Eocene Formations of Maryland. Trans. Md. Acad. Sci., vol. i, 1889, pp. 45-72. This paper contains many descriptions of Cretaceous and Eocene strata in this county together with a general description of these formations as repre- sented in the entire State. A list is given of all Eocene fossils recognized up to that time. Warp, Lester F. The Geographical Distribution of Fossil Plants. 8th An. Rept. U. S. Geol. Surv., 1886-87, Washington, 1889, pt. ii, pp. 663- 960, maps. Several localities where fossil plants have been obtained from Potomac strata are mentioned. Beltsville is especially mentioned as where both fossil plants and remains of dincsaurs were found in an old iron mine. 1890. Crarx, Wn. B. Third Annual Geological Expedition into South- ern Maryland and Virginia. Johns Hopkins Univ. Cir. No. 81, vol. ix, 1890, pp. 69-71. Contains a description of the Fort Washington bluff. Parrerson, Harry J. Report of the Chemist. 2nd An. Rept. Md. Agri. Exper. Sta., College Park, 1890, pp. 67-94. The different kinds of marls occurring in Maryland are described and analyses of many are given including two samples of marls from Upper Marlboro and two from Piscataway Creek. 5G THE PHYSICAL FEATURES OF PRINCE GEORGES COUNTY Unter, P. R. Notes and Illustrations to Observations on the Cretaceous and Eocene Formations of Maryland. Trans. Md. Acad. Sci., vol, i, pp. 97-104. The Fort Washington bluff and the Eocene and Miocene exposures at Upper Marlboro are described. The Cretaceous strata at the former locality are correlated with the lower and middle marl! beds of New Jersey. 1891. CrarKx, Wo. B. Correlation Papers — Eocene. Bull. U. S. Geol. Surv., No. 83, Washington, 1891, 173 pp. 2 maps. (Abst.) Johns Hopkins Univ. Cir. No. 108, vol. xii, 1893, p. 50. Contains a discussion of all the literature concerning the Eocene of the United States published up to that time. The distribution and characteristics of the Maryland Eocene deposits are briefly described. Crarx, Wa. B. Report on the Scientific Expedition into Southern Maryland. (Geology, W. B. Clark; Agriculture, Milton Whitney ; Archaeology, W. H. Holmes.) Johns Hopkins Univ. Cir. No. 89, vol. x, 1891, pp. 105-109. Contains a description of the Fort Washington bluff and also short descrip- tions of the distribution and lithologic characteristics of the Mesozoic and Cenozoic formations of the Coastal Plain. Darron, N. H. Mesozoic and Cenozoic Formations of Eastern Virginia and Maryland. Bull. Geol. Soe. Amer., vol. ii, 1891, pp. 431-450, map sections. (Abst.) Amer. Geol., vol. vii, 1891, p. 185. (Abst.) Amer. Nat., vol. xxv, 1891, p. 658. Contains a description of the Potomac, Severn (Marine Cretaceous), Pamunkey (Eocene), Chesapeake (Miocene), and Appomattox (Lafayette) formations as known at that time. Linpenxout, A. Notes on the submarine channel of the Hudson River and other evidences of Postglacial Subsidence of the Middle Atlantic Coast Region. Amer. Jour. Sci. 8rd ser., vol. xli, 1891, pp. 489-499, pl. xviii. Some statements are made concerning the submerged channel of the Potomac River. McGerrz, W J. The Lafayette Formation. 12 An. Rept. U. S. Geol. Surv., part i, 1890-91. Washington, 1891, pp. 347-521. The general characteristics of the entire Coastal Plain and of each of the formations composing it are discussed at length. Cr =| MARYLAND GEOLOGICAL SURVEY McGzez, W J, Witttas, G. H., Wituts, Bartzy, and Darron, N. H. Geology of Washington and Vicinity. In Guide to Wash- ington and its Scientific Institutions. Compte rendu, International Congress of Geologists, 1891. House Misc. Doc., 53rd Cong., 2nd sess. vol. xiii, No. 107, pp. 219-251. Contains descriptions of physiographic and geologic features in the vicinity of Washington and a general description of the entire Coastal Plain. Patrerson, Harry J. Report of the Chemist. 3rd An. Rep. Md. Agri. Exper. Sta., College Park, 1891, pp. 118-129. The analyses of eight samples of marls from Seat Pleasant are given. Wuirr, C. A. Correlation papers. Cretaceous. Bull. U. S. Geol. Surv. No. 82, 1891, 273 pp., 3 pl.’ House Misc. Doc., 52nd Cong., 1st sess., vol. xx, No. 25. Contains brief descriptions of the distribution and characteristics of the marine and non-marine Cretaceous strata of the State. Wootman, Lewis. Artesian wells and water-bearing horizons of Southern New Jersey (with a “note on the extension southward of diatomaceous clays, and the oceurrence there of flowing artesian wells.” ) New Jersey Geol. Surv., Rep’t. State Geologist for 1890, Trenton, 1891, pp. 269-276. The diatomaceous earth bed outcropping in the vicinity of Nottingham is mentioned. It is said to contain the diatom Heliopelta. This bed is thought to extend continuously from New Jersey to North Carolina. 1892. Crark, Wm. B. The Surface Configurations of Maryland. Monthly Rept. Md. State Weather Service, vol. ii, 1892, pp. 85-89. General summary of the physical features of the State. Dati, W. H., and Harris, G. D. Correlation Papers—Neocene. Bull. U. S. Geol. Surv. No. 84, 1892, 349 pp., 3 maps, 43 figures. House Mise. Doc., 52nd Cong., Ist sess., vol. xliii, No. 337. Contains a full discussion of all the literature of the Miocene and Pliocene of the United States published up to that time. Tentative correlations are made. Parrerson, H. J. Report of the Chemist. 4th An. Rep. Md. Agri. Exper. Sta., 1891, Annapolis, 1892, pp. 297-346. Analyses are given of Eocene marls from Upper Marlboro, Seat Pleasant, and T. B. and of a Cretaceous marl sample from Seat Pleasant. 53 THE PHYSICAL FEATURES OF PRINCE GEORGES COUNTY Scrarr, J. Tuomas. The Natural Resources and Advantages of Maryland, being a complete description of all the counties of the State and the City of Baltimore. Annapolis, 1892. Contains a general geographic description of Prince George’s county with brief statements of the mineral products. Unter, P. R. Albirupean Studies. Trans. Md. Acad. Sci., vol. i, 1890-92, pp. 185-202. The Albirupean and Potomac formations are described in detail and many references made to localities in this county. Much of Uhler’s Albirupean formation is now referred to the Magothy, particularly the lignitic black clays while parts are included in the Potomac group. Wittirams, G. H., and Crarx, Wm. B. Report on short excursions made by the Geological Department of the University during the Autumn of 1891. Johns Hopkins Univ. Cir. No. 95, vol. xi, 1892, pp. 37-39. The section of Potomac, Marine Cretaceous, Eocene, and Pleistocene strata exposed at Fort Washington is briefly described. 1893. Crark, W. B. Physical Features [of Maryland]. Maryland, its Resources, Industries, and Institutions. Baltimore, 1893, pp. 11-54. Contains short descriptions of the topography, climate, water supply, and water power of the different portions of the State. Darton, N. H. The Magothy Formation of Northeastern Mary- jand. Amer. Jour. Sci., 3d ser., vol. xiv, 1893, pp. 407-419, map. The Magothy formation is differentiated from other Cretaceous strata with which the deposits had previously been included. The distribution and characteristics of the formation are discussed and many local details described. A map showing the distribution of the formation is given. Hirt, Roserr T. Clay Materials of the United States. Mineral Resources United States, 1891. Washington, 1893. Brief mention is made of the Columbian and Potomae clays of the county and of the District of Columbia. Keyser, W. Iron. Maryland, its Resources, Industries and Insti- tutions, pp. 100-112. Baltimore, 1893. An historical discussion of the iron industry in Maryland. MARYLAND! GEOLOGICAL SURVEY 59 Witney, Mrnron. Description of the Principal Soil Formations of the State [Maryland]. Maryland, its Resources, Industries and Tnstitutions. Baltimore, 1893, pp. 181-211. Contains descriptions of the soils of the State, their distribution, origin, and adaptabilities. Wuirney, Mrrron. The Soils of Maryland. Md. Agri. Exper. Sta. Bull. No. 21, College Park, 1893, 58 pp., map. The principal soils of the State are described and their adaptability to different kinds of crops discussed. A map is given showing their general distribution. WriuuraMs, G. H. Mines and Minerals of Maryland. Maryland, its Resources, Industries and Institutions, Baltimore, 1893, pp. 89-153. Reference is made to the Eocene greensand marls of the county. WitiiaMs, G. H., and Crarx, W. B. Geology of Maryland. Maryland, its Resources, Industries and Institutions, Baltimore, 1893, pp. 55-89. The different geological formations recognized at that time are briefly described. Several important Eocene and Cretaceous fossiliferous localities in this county are mentioned. 1894. Darton, N. H. Outline of Cenozoic History of a Portion of the Middle Atlantic Slope. Jour. Geol., vol. ii, 1894, pp. 568-587. A description of the formations of the Atlantic Coastal Plain and a resumé of the geological history of the region. Darron, N. H. Artesian Well Prospects in Eastern Virgini:, Maryland, and Delaware. Trans. Amer. Inst. Min. Eng., vol. xxiv, 1894, pp. 372-397, pls. i-ii. Contains a general description of the Atlantic Coastal Plain formations with records of some of the important artesian wells of Eastern Maryland and Virginia with a discussion of artesian water conditions in those areas. Record of a 384-foot well at Bowie is given. Harris, G. D. On the Geological Position of the Eocene Deposits of Maryland and Virginia. Amer. Jour. Sci., 3rd ser., vol. xlvii, 1894, pp. 301-304, figs. 1-3. The writer correlates the Eocene of Virginia and Maryland with the Bell’3 Landing substage of Alabama. 60 THE PHYSICAL FEATURES OF PRINCE GEORGES COUNTY Maryitanp Stare Werarner Servicer. The Climatology and Physical Features of Maryland. lst Bien. Rep. Maryland State Weather Service for years 1892-1893. Baltimore, 1894. A general discussion of the geology, topography, soils and climate of the State. Newe tt, F. H. Results of Stream Measurement. 14th An. Rep. U. S. G. S., 1892-1893, part ii, pp. 89-155. Gives data concerning the Potomac River near Washington. Warp, L. F. Fossil Cycadean Trunks of North America, with a Revision of the Genus Cycadeoidea Buckland. Proc. Biol. Soc., Washington, vol. ix, pp, 75-88. The species of cycads found in the Potomac deposits of Maryland are included in the list of forms given. Warp, L. F. Recent Discoveries of Cycadean Trunks in the Potomac Formation of Maryland. Bull. Torry Bot. Club, vol. xxi, 1894, pp. 291-299. A short account is given of the cycad remains found in the Potomac deposits of Maryland and the manner in which a collection of them has been brought together. The region about Muirkirk has furnished more specimens than any other locality in the Atlantic Coastal Plain. 1895. Anonymous. Vert. Fauna of Potomac Formation in Maryland. Science, N. S., vol. i, 1895, pp. 362. Notice of a collection of reptilian remains from the vicinity of Muirkirk made by A. Bibbins. ; Bissrys, Artuur. Notes on the Paleontology of the Potomae Formations. Johns Hopkins Univ. Circ., vol. xv, 1895, pp. 17-20. The author describes the occurrence of cycads and other plant remains in the Potomac deposits of Maryland. The Contee and Muirkirk localities are described in detail. Crark, W. B. Cretaceous Deposits of the Northern Half of the Atlantic Coastal Plain. Bull. Geol. Soe. America, vol. vi, 1895, pp. 479-482. The Matawan and Navesink formations are said to occur in Prince George’s county. MARYLAND GEOLOGICAL SURVEY 61 Crark, Witt1am B. Descriptions of the Geological Excursions made during the Spring of 1895. Johns Hopkins Univ. Cire., vol. xv, 1895, pp. 1-2. Brief descriptions of all the Coastal Plain formations are given while the strata exposed in the bluffs at Fort Foote and Fort Washington are mentioned. Crarx, Wn. B. Contributions to the Eocene Fauna of the Middle Atlantic Slope. Johns Hopkins Univ. Cire., vol. xv, 1895, pp. 3-6. The author makes the following statement: “I am, therefore, strongly of the opinion, upon both geological and paleontological grounds, that the Eocene deposits of the Middle Atlantic slope represent the greater portion of the Eocene series of the Gulf, its highest members alone excepted.” Many localities in Maryland and Virginia are given where Eocene fossils have been obtained and many new species are described. Merritt, Grorer P. Disintegration of the Granitic Rocks of 2 5 the District of Columbia. Bull. Geol. Soc. America, vol. vi, 1895, pp. 321-332, pls. 16. Describes the weathering of foliated micaceous granite in the northwestern portion of the District of Columbia. Merritt, G. P. The Formation of Sandstone Concretions. Proc. U. S. National Museum, vol. xvii, 1895, pp. 87-88, pl. The writer describes some concretions from the Potomac deposits. Warp, Lester F. The Potomac Formation. 15th An. Rep. U. S. G. S., Washington, 1895, pp. 307-397, 3 pls., 5 figs. General description of the Potomac deposits as known at that time. Mary- land details of the strata in this county are given. 1896. Crark, W. B. The Eocene Deposits of the Middle Atlantic Slope in Delaware, Maryland, and Virginia. Bull. U. S. G. S. No. 141, 167 pp., 40 pl. An exhaustive study of the Eocene in which the stratigraphy and paleon- tology of the deposits are discussed in detail. 62 THE PHYSICAL FEATURES OF PRINCE GEORGE'S COUNTY Crark, W. B. The Potomac River Section of the Middle Atlantie Coast Eocene. Amer. Jour. Sc., 4th ser., vol. i, 1896, pp. 365-374. Sections along the Potomac River are given and the characteristics of the Maryland and Virginia Eocene deposits described. The writer states that “the Middle Atlantic Slope Eocene represents in a broad way all or the major vart of the Lignitic, Buhrstone and Claiborne of Smith . . . and perhaps even more.” Darron, N. H. Artesian Well Prospects in the Atlantic Coastal Plain Region. Bull: 138, U. S:'G. S:, 232 pp:, 19) pls: Contains a brief description of the Coastal Plain formations of the State with a discussion of their water-bearing powers. Records are given of a 150-foot well at Agricultural College, of a 384-foot well at Bowie, and a 14814- foot well near Laurel, and a 222-foot weil at Marlboro. Fontrarye, W. M. Potomac Formation in Virginia. Bull. U. S. G. S., 145, 149 pp., 2 pls. Brief descriptions of the Potomac deposits of Maryland given. ‘Two series of strata are said to occur in Maryland. From a study of the flora the Potomac is said to be of Middle or Lower Neocomian age. Marcou, Jutres. The Jura in the United States. Science, n. s., vol. iv, 1896, pp. 945-947. Agrees with Marsh that the Potomac deposits belong to the Upper Jurassic. Marsu, O. C. The Jurassic Formation on the Atlantie Coast. Science, n. s., vel. iv, pp. 805-816. The author maintains the Jurassic age of the Potomac deposits. Marsu, O. C. The Dinosaus of North America. 16th An. Rep. U.S. G. S., part i, pp. 195-413, 84 pls., 66 figs. Dinosaurian remains from the Potomac deposits of Prince George’s county are described and figured. Warp, Lester F. Some Analogies in the Lower Cretaceous of Europe and America. 16th An. Rep. U.S. G. S., part i, pp. 463-542, pls. 97-107. From a comparison of the floras the writer correlates the Potomac strata with the Wealden of England. (=p) Co MARYLAND GEOLOGICAL SURVEY Warp, L. F. Age of the Island Series. Science, n. s., vol. iv, pp. 757-760. The author brings forward additional evidence to prove that the Potomac deposits belong to the Lower Cretaceous. Sie Crarx, W. B. Outline of the Present Knowledge of the Physical Features of Maryland, Embracing an Account of the Physiography, Geology, and Mineral Resources. Md. Geol. Survey, vol. i, 1897, pp. 141-228, pls. 6-13. Contains a description of all the geologic formations of the State recognized at that time. Criarx, W. B., with R. M. Baee, and G. B. SuHarruckx. Upper Cretaceous Formations of New Jersey, Delaware and Maryland. Bull. Geol. Soc. of America, vol. viii, 1897, pp. 315-358, pls. 40-50. Contains a full description of each of the Marine Cretaceous formations of the Northern Atlantic Coastal Plain. Crark, W. B., and Brasins, Arruur. The Stratigraphy of the Potomac Group in Maryland. Jour. Geol., vol. v, 1897, pp. 479-506. Contains a general description of the Potomac deposits of the State which are divided for the first time into four formations, viz: Patuxent, Arundel, Patapsco and Raritan. 1898. Baee, R. M., Jr. The Tertiary and Pleistocene Foraminifera of the Middle Atlantic Slope. Amer. Pal. Bull., vol. ii, No. 10, Ithaca, 1898, 54 pp., 3 pls. The following forms are described from the Eocene deposits at Upper Marlboro: Yextularia sagittula, Nodosaria consobrina var. emaciata and Nodosaria communis and Vaginulina legumen from Sunnyside. Baae, Rurus Marurr. The Occurrence of Cretaceous Fossils in the Eocene of Maryland. Amer. Geol., vol. 22, 1898, pp. 370-375. Specimens of Terebratula harlain “were found in the Eocene marl of Prince George’s county in a bank by the roadside on western branch of the Patuxent River about three miles west of Leeland. . . . The greensand at this cut- ting in the road is very fossiliferous and carries the common lower Eocene fauna, Ostrea compressirostra say, Cucullaea giganter Conrad, Cytherea orata Regers, and several others.” 64 THE PHYSICAL FEATURES OF PRINCE GEORGES COUNTY McGrr, W J. Geographic Development of the District of Columbia. National Geog. Mag., vol. ix, 1898, pp. 317-3238. The geography and geology of the region about Washington are described and the conditions that prevailed during the formation of the Columbia deposits discussed. 1899. Appr, CLEVELAND, Jr. General Report of the Physiography of Maryland. Maryland Weather Service, vol. i, Baltimore, 1899, pp. 41-216, pls. 3-19, figs. 1-20. Contains a full description of the physiographic features of the State. 1900. Asser, CLEVELAND, Jr. The Physiographic Features of Maryland. Bull. Amer. Bus. Geog., vol. i, pp. 151-157, 242-248, 342-355, 2 figs., 1900. A concise statement of the important physical features of each of the three physiographic provinces of the State. McGee, W J. Occurrence of the Pensauken ( 7) Formation. Abstract Am. Ass. Adv. Se. Proc., vol. lvix, p. 187. In a deep cutting on Sixteenth street, Washington, there is an exposure that seems to reveal two unconformable gravel formations overlying the Potomac strata. The lower is provisionally correlated with the Pensauken of New Jersey while the upper is said to be undoubted Earlier Columbia. 1901. Crarxk, W. B. and G. C. Martin. The Eocene Deposits of Mary- land. Md. Geol. Surv., Eocene, Balto., 1901, pp. 21-92, 14 pls. Describes the general stratigraphic relations, distribution, characters. origin of the materials, and the stratigraphic and paleontologic character- istics of the Eocene strata. Crark, W. B. With collabo ators. Systematic Paleontology. EKocene. . Md. Geol. Surv., Eocene, Balto., 1901, pp. 95-215, pls. 10-64. Contains descriptions and figures of all Eocene fossils known to occur within the State. MARYLAND GEOLOGICAL SURVEY 65 Darton, N. H., and ArrHur Keitru. Washington Folio, Dis- trict of Columbia, Maryland and Virginia. U. S. G. S., Geol. Atlas, folio 70, Washington, 1901, 4to, 7 pp., 5 maps. A complete description of the geology of the Washington region including the greater portion of Prince George’s county. Suarruck, Grorcre Burspank. The Pleistocene Problem of the North Atlantie Coastal Plain. Johns Hopkins Univ. Cire., vol. xx, 1901, pp. 69-75. Amer. Geologist, vol. —, 1901, pp. —. The views of McGee, Darton, and Salisbury concerning the Pleistocene deposits are summarized and compared with the writer’s views. The wave- built terrace deposits are referred to four different formations, the Talbot, Wicomico, Sunderland, and Lafayette, the first three of which constitute the Columbia group. These formations are said to be separated by erosional unconformities. 1902. BonstEEL, Jay A., and Party. Soil Survey of Prince George's County, Maryland. Field Operations of the Bur. of Soils, 1901, pp. 173-210, fig. 6, pls. 21-25, Washington, 1902. Contains a brief resumé of the geology of the county and a description of each of the types of soil recognized in the county. Cuark, W. B. and Brssins, A. Geology of the Potomac Group in the Middle Atlantic Slope. Bull. Geol. Soe. Amer., vol. xiii, 1902, pp. 187-214, pls. xxii-xxviii. Contains a full discussion of the Potomac deposits with a map showing the distribution of the four formations in Maryland. Darton, Netson Horatio. Preliminary List of Deep Borings in the United States. Part I, Alabama-Montana. U.S. Geol. Surv., Water-Supply and Irrigation Paper No. 57, 60 pp., Wash- ington, 1902. Contains data in regard to some deep wells in the District of Columbia. Ries, Heryrrcn. Report on the Clays of Maryland. Md. Geol. Surv., vol. iv, 1902, pp. 203-505, pls. xix-lxix. Contains a complete description of the clay deposits and clay industries of the State with many detailed descriptions of the clays of Prince George’s county. 66 THE PHYSICAL FEATURES OF PRINCE GEORGES COUNTY Vaueuan, T. Wayztanp. In Addition to the Coral Fauna of the Aquia Eocene Formation of Maryland. Washington Biol. Soc. Proc., vol. 15, pp. 205-206, 1902. Paracyathus marylandicus Vaughan and Haimesiastraea conferta Vaughan are reported from the Eocene deposits at Upper Marlboro. The latter form had not previously been known to occur north of Alabama and the author considers its occurrence as important in that it furnishes additional evidence for correlating the Aquia of Maryland and Virginia with the Gregg’s or Bell’s Landing horizon of Alabama. 1903. ABBE, CLEVELAND, Jr. Die Fall-Linie de stidéstlichen Vereinig- ten Staaten. Sonder-Abdruck aus den “Vierteljahrsheften fiir den geographischen Unterricht” (Herausgegeben von Prof. Dr. Heid- erich), Wien HOlzel. ii, Jahrg, 4, pp. 204-210, 2 pls., 1908. The “Fall-line”’ separating the Piedmont Plateau and the Atlantic Coastal Plain is described in considerable detail. Ries, Heryrticu. The Clays of the United States East of Mis- sissippl River. U. S. Geol. Surv., Prof. Paper No. 11, pp. 1384-149, 1903. Describes the clay bearing formations of the county and gives analyses and physical characteristics of the most important clays. 1904. Casr, E. C., Eastman, C. R., Martin, G. C., Utricu, HE. O. Basser, R. 8., Guenn, L. C., Crazx, W. B., Vauenan, T. W., Baae, R. M., Jz., Hotticx, ArrHur, and Boyer, C.S. Systematic Paleontology of the Miocene Deposits of Maryland. Md. Geol. Surv., Miocene, pp. 1-508, pls. 10-135, Balto., 1904. Contains descriptions and illustrations of all Miocene fossils recognized in Maryland up to that time. Many forms from this county are included. CrarKk, Witiram Buritock; SuHatrtucK, Georce Burpanx; and Day, Witttam Heatry. The Miocene Deposits of Maryland. Md. Geol. Surv., Miocene, pp. xxiii-clv, pls. 1-9, Balto., 1904. Contains a full account of the Miocene strata of the State. MARYLAND GEOLOGICAL SURVEY 67 Cuark, Witt1am Buttock. The Matawan Formation of Mary- land, Delaware, and New Jersey, and its relation to overlying and underlying formations. Amer. Jour. Sci., 4th ser., vol. 18, pp. 435-440, 1904. Johns Hopkins Univ. Cire., 1904, No. 7, pp. 28-35. The Matawan formation as it occurs throughout New Jersey, Delaware and Maryland is discussed as well as the Magothy and Monmouth formations with which it is in contact. A table giving the approximate correlation of the Atlantic Coast Cretaceous formations and their European equivalents is also given. 1905. Darron, Netson H., and Futter, Myron L. Underground Waters of Eastern United States. U. S. Geol. Surv., Water-Supply and Irrigation Paper No. 114, pp. 114-126, 3 pls., Washington, 1905. Contains a brief description of the geology of the Coastal Plain of Mary- land, particularly with reference to the artesian water-bearing horizons. Brief data concerning several deep wells and mineral springs from this county are given. Warp, Lester F., with the collaboration of Fonrarnr, WILLIAM M., Brssrns, Arruur, and Wievanp, G. R. Status of the Mesozoic Floras of the United States. Second Paper. Wasa Geol. sunve, Mon... vol. xlviliz btu. lext, 616 pps Pt. ih Plates; 119 pls., Washington, 1905. Contains general and detailed descriptions of the Potomac deposits and the plant remains found in them. Many localities in Prince George’s are men- tioned. A table of correlation showing the relationships of the Maryland and Virginia members of the group is included. 1906. Suatrtruck, Grorak Burspanx. The Pliocene and Pleistocene Deposits of Maryland. Md. Geol. Surv., Pliocene and Pleistocene, pp. 21-137, plates, Baltimore, 1906. Contains a full description of the surficial deposits of the State with many local details. 68 THE PHYSICAL FEATURES OF PRINCE GEORGES COUNTY Berry, Epwarp W. Contributions to the Mesozoic Flora of the Atlantic Coastal Plain—lI. Bulletin Torrey Bot. Club, vol. xxxiii, pp. 163-182, pl. 7-9. Describes Fossil Plants from the Magothy formation of New Jersey, Dela- ware and Maryland including one species from Prince George’s county. Wietann, G. R. American Fossil Cyeads. Carnegie Inst., Washington, Pub. No. 34, 4 to 296 pp., 138 figs, 50 pls., 1906. The cycads found in the Potomac beds of Maryland are mentioned while the structure, growth, and relationships of cycads are discussed in great detail. 1907. SuattTuck, Grorce Bursanx, Mirier, Bensamin. LeRoy, and Bresins, ArrHuR. Patuxent Folio, Maryland—District of Colum- bia. U. S. Geol. Surv., Geol. Atlas of U. S., folio No. 152, Washington, 1907, 4to., 12 pp., 3 maps. Contains a description of each of the formations outcropping in the area which embraces a large portion of Prince George’s county and shows their distribution on the accompanying map. 1908. Crark, Wm Buxiiock. Results of a recent investigation of the coastal plain formations in the area between Massachusetts and North Carolina. Bull. Geol. Soc. Amer., vol. xx, 1908, pp. 646-654. 1910. Berry, Epwarp W. Contributions to the Mesozoic Flora of the Atlantic coastal plain —IV. Maryland. Bulletin Torrey Bot. Club, vol. xxxvii, 1910, pp. 19-29, pl. viil. THE PHYSIOGRAPHY OF PRINCE GEORGE'S COUNTY BY BENJAMIN L. MILLER In TRODUCTORY. Maryland is divisible into three grand physiographic provinces, each with certain distinguishing characteristics. These provinces are, beginning with the most easterly, the Coastal Plain, the Pied- mont Plateau, and the Appalachian Region. These three provinces form bands of somewhat varying width that extend in a northeast-southwest direction, roughly parallel to the shore line, from New England to the Gulf of Mexico. All three are typically represented in Maryland. Garrett, Allegany and Wash- ington counties form a part of the Appalachian Region; Frederick, Carroll, Montgomery, Howard, and the northern and northwestern portions of Baltimore, Harford and Cecil counties lie within the Piedmont Plateau; while the remaining portion of the State consti- tutes a part of the Coastal Plain province. The elevations, the characteristics of the streams, and the lithologic character and structure of the rocks serve as criteria for the separa- tion of these three provinces. In some places, however, there is such a gradation from one to the other that some difficulty is encountered in drawing the exact boundary line. Passing from the coast west- ward, the country rises at first gradually until the eastern border of the Piedmont Plateau is reached, then more rapidly to the Blue Ridge which marks the western boundary of the Piedmont Plateau, and finally in the Appalachian Region the summits of the Appala- chian Mountains are reached in the western portion of the State. The streams of the three provinces are essentially different. The estuaries of the Coastal Plain, occupying broad open valleys form a 70 THE PHYSIOGRAPHY OF PRINCE GEORGE S$ COUNTY striking contrast to the swift streams of the other two provinces which flow in steep rock-walled gorges; while the superimposed, meandering streams of the Piedmont Plateau are markedly unlike the Appalachian streams which flow in structural valleys. But probably the greatest distinction between the three provinces is due to the character of the rocks. The unconsolidated sediments of the Coastal Plain, dipping gently toward the ocean, are sharply sepa- rated from the contorted metamorphosed igneous intruded strata of the Piedmont Plateau, while these in turn can be readily differenti- ated from the unmetamorphosed Appalachian Region limestones and sandstones which have been thrown into broad, open folds, forming longitudinal ridges and valleys with a northeast-southwest trend. Prince George’s County lies almost entirely within the eastern province and is known as a Coastal Plain county, although its ex- treme western portion forms a part of the Piedmont Plateau. TopocraPpHuic [)ESCRIPTION. As previously stated, Prince George’s County contains portions of two great physiographic provinces which have characteristic topo- graphic features. The topography of the Piedmont Plateau in this county, however, is not characteristic of the general topography of the province for the reason that it has been greatly modified by the Coastal Plain deposits overlying it. It is represented only in the uplands west and northwest of Washington and in small areas along the western border of the county between Washington and Laurel. Within the area under discussion the northwest portion of the Dis- triet of Columbia shows the best examples of Piedmont Plateau topography. Here occur many hills, irregular in outline with rounded flat-topped summits separated from each other by steep, precipitous valleys. Those hills without coverings of Coastal Plain sediments are seldom flat-topped but instead slope gradually in all directions for a short distance from the highest point, and then very rapidly to the streams occupying the narrow gorge-like valleys. In the Coastal Plain portion of the county the flat-topped stream divides separated by broad open valleys afford a striking contrast to the topography of the Piedmont Plateau. The broad tidal estuaries MARYLAND GEOLOGICAL SURVEY -! — that extend inland to the eastern border of the Piedmont Plateau are the most prominent characteristics of the Coastal Plain of Maryland. On the eastern side of Chesapeake Bay these streams are occupied by tide-water almost to their heads while the tributary streams are also very little above tide, consequently stream erosion has accomplished very little work and the country is in the main extremely flat. On the western shore different conditions prevail as here the larger streams are estuaries up as far as the ‘“Fall-line,” but the heads of the tributaries lie a few hundred feet above tide and hence they have been able to do considerable erosion. For this reason the topography of the western shore Coastal Plain is much more diversified than that of the Eastern Shore, Prince George’s County exhibiting a topog- raphy of the western-shore type. The elevations in Prince George’s County range from the level of tide-water in the estuaries to slightly more than 420 feet above sea level. The highest point is a small hill near the Montgomery County line a short distance southwest of Laurel. At Tenley(town) in the District of Columbia a hill rises to the height of 400 feet. Both of these hills are found in the Piedmont Plateau province, although the capping of the hills is Pleistocene sand and gravel. From the Pied- mont Plateau border the stream divides slope gently to the southeast, where they have an average elevation of about 140 feet. If the stream valleys were filled up the result would be a gently sloping country with an average of about 7 feet per mile, a grade so low as to be practically unnoticeable, thus causing the region to appear as a flat monotonous plain. It is in this very gently sloping country that the Potomae and Patuxent rivers and their tributary streams have cut their drainage channels and have by so doing developed a somewhat diversified topography. The ease with which different strata or formations are worn away by erosion is usually the most important factor in the determination of the topographical configuration of any region. It is this which is mainly responsible for the direction of the streams and for the rela- tive elevations, especially in a region which has not been subjected to orogenic movements and where, as a result, the strata are approxi- mately horizontal. “I bo THE PITYSIOGRAPHY OF PRINCE GEORGE'S COUNTY In the Piedmont Plateau the topography is mainly due to these facts and almost invariably the broader valleys have been developed in limestone regions while the ridges are composed of less easily eroded rocks. In the Coastal Plain where the strata are almost entirely composed of unconsolidated sediments there is in general little difference in the rate at which erosion proceeds. However, it can be seen in several places that the Potomac strata are generally easily eroded because of the large amount of sand present. As a result of the difference in the ease of erosion of the Potomae strata a strike valley occupied by Anacostia River and its tributaries has been produced in this region. The valley is carved out of Potomac sands and clays and is confined between the crystalline rocks of the Piedmont Plateau on the west and the younger formations of the Upper Cretaceous and Tertiary on the east. Contrary to what might be expected the eastern wall of this valley is even steeper than the western. This is especially noticeable in the southeastern portion of the District of Columbia. The most prominent feature in connection with this difference in ease of erosion has been its effect upon the direction of the streams in the area in which the Potomac strata form the surface formations. A glance at the map will show that the escarpment between the Lower and Upper Cretaceous rocks has served as an efficient divide between two sets of secondary streams. In only one instance in this county does a secondary stream flowing mainly through the area of the later formations drain any Potomac area. The Western Branch is the sole exception as it has cut through the escarpment just west of Wood- moor. The larger volume of water carried by the Western Branch has aided this stream in pushing its head backward into the Potomac area. It is also probable that the ease with which the Potomac material is eroded is responsible for the change in direction of the Potomac River where it emerges from the crystalline rocks. This stream traverses the Piedmont Plateau in a general southeasterly course regardless of the character of the country rock, but as soon as it strikes the Potomae strata it changes its course suddenly and flows southward in a direction almost parallel to the strike. This direc- MARYLAND GEOLOGICAL SURVEY. PRINCE GEORGE'S COUNTY, PLATE I. Fic. 1.—vVIEw ALONG PAINT BRANCH, SHOWING THE ROCKY CHANNEL CHARACTERISTIC OF PIEDMONT STREAMS, i Re a y a Fic. 2.—vIEW OF PATUXENT RIVER AT PRIEST BRIDGE, SIIOWING THE LOW MUDDY VEGETATION- COVERED BANKS CHARACTERISTIC OF COASTAL PLAIN STREAMS. i MARYLAND GEOLOGICAL SURVEY —~I os tion it maintains beyond the limits of the area under discussion, though it does finally resume its southeastern course, cutting across the Tertiary strata to Chesapeake Bay. TOPOGRAPHIC FEATURES. Prince George’s County as a whole exhibits five general topo- graphic features, which are usually very distinct. These vary greatly in the amount of surface that they occupy, but the most noticeable distinction is that they lie at different elevations. Tide Marshes.—The first of these topographic features to be described consists of the tide marshes found in the valleys of most of the larger estuaries, particularly of Patuxent and Anacostia rivers and Piscataway Creek. These extend over a number of square miles and lie at a level so low that the tides frequently submerge them in part. The small streams that empty into many of the estuaries meander through these marshes, which are rapidly encroaching on them. These marshes are filled with a growth of sedges and other marsh plants, which aid in filling up the depressions by serving as obstructions to retain the mud carried in by streams and by furnish- ing a perennial accumulation of vegetable débris. Lafayette Plain.—The Lafayette plain is the highest of the plains developed within the Coastal Plain province. It has a considerable extent in this county southeast of Anacostia, forming the divide between the valley of Patuxent River on the east and the basin of Potomac River on the west. Throughout this region the margin of the Lafayette plain has been extensively removed by stream action, but the central portions have been practically undisturbed. Sunderland Plain.—The Sunderland plain lies at a higher eleva- tion than the Wicomico and extends from about 100 feet to about 200 feet above sea level. It is usually separated from the Wicomico plain by an escarpment, and in most places another escarpment marks its contact with the next plain above. The escarpment separating the Wicomico from the Sunderland plain is one of the most striking and constant topographic features in the Coastal Plain of Maryland. T4 THE PHYSIOGRAPHY OF PRINCE GEORGE S$ COUNTY It occupies the highest portions of the divide between Chesapeake Bay and Patuxent River and also is well developed along the western side of Patuxent Valley as far north as the mouth of Western Branch. In the valleys of Mattawoman, Piscataway and Henson creeks and Anacostia River the Sunderland plain, though present, is represented only by remnants. The surface of this plain reaches an altitude of about 180 feet at Charlotte Hall, a short distance beyond the southern boundary of Prince George’s County, and of 200 feet near Anacostia. It has suffered more stream erosion than the Talbot and Wicomico plains, which lie at lower levels. Wicomico Plain.—The Wicomico plain lies at a higher level than the Talbot, from which it is in many places separated by an escarp- ment varying in height from a few feet to 10 or 12 feet. At some places this escarpment is absent, so that there seems to be a gradual passage from the Talbot plain to the Wicomico. It is present, how- ever, at so many different places that there is little difficulty in deter- mining the line of separation between the two plains. The base of the escarpment hes at an elevation of about 40 feet. From that height the Wicomico plain extends upward to an elevation of about 100 feet, where it is in turn separated from the next higher plain by an escarpment. The Wicomico plain is older than the Talbot and has suffered more erosion. The streams which cross it have cut deeper valleys than those in the Talbot plain and have widened their basins to such an extent as to destroy, in great measure, the original continuity of its level surface. Enough of this surface remains, however, to indicate the presence of the plain and to permit its identification. The escarpment which separates this plain from the Sunderland plain below is well defined in the region about Anacostia, where it attains a height of about 50 feet. Near Aquasco, and just beyond the southern border of the county in the vicinity of Charlotte Hall, the escarpment is present, but here it does not exceed 20 feet in height. Throughout the rest of the County it seems never to have existed or to have been destroyed or so greatly modified by erosion that its determination is rendered uncertain. The surface of this plain ranges in elevation from about 200 feet in the southeastern =I Or MARYLAND GEOLOGICAL SURVEY portion of the county to about 300 feet in the hills southeast of Washington. Talbot Plain.—The Talbot plain borders the tide marshes and ex- tends from sea level to an altitude of about 45 feet. It is present throughout the county along the larger streams. In the valley of the Patuxent River this plain is characteristically developed. Here it extends in an almost continuous belt from the southern margin of the county to Hills Bridge, growing gradually narrower as it ascends the streams and broken only by the shallow valleys of small streams which cut across it in their course to Patuxent River. North of Hills Bridge and on the western branch of ,the Patuxent, the Talbot plain is present only in scattered remnants. In the western portion of the county this plain is well developed in the lower valleys of Piscataway and Henson creeks, and occurs in an unbroken flat ex- tending up the valley of Anacostia River as far as College Park. The Talbot plain has been dissected by stream action less than any of the other plains described below. THE DRAINAGE OF PRINCE GEORGE'S COUNTY. The drainage of Prince George’s County is comparatively simple, as a result of the simple structure of the Coastal Plan formations and the contiguity of the region to Chesapeake Bay. While prac- tically all portions of the County are naturally drained there are numerous small areas in which there is little surface drainage. Such areas are most common on the wide stream divides near Brandywine. Numerous small upland swamps from which the surface water es- capes only through percolation or evaporation occur in this vicinity. In the northwestern portion of the county where the stream divides are very narrow the only undrained regions are the tide-water marshes already described. Stream Divides.—In the examination of the stream divides of Prince George’s County two peculiarities attract attention. The first is their relative widths and the second their asymmetrical develop- ment. In the southern portion of the County where the Lafayette 76 THE PHYSIOGRAPHY OF PRINCE GEORGE'S COUNTY plain is so well developed the flat-topped divides are in several instances as much as two miles in width, while in the northern por- tion they are seldom more than one-half mile wide. The difference is due to the relative ease with which the different strata are eroded as the geologic map shows the narrow divides in the Potomac strata and the wide ones in the regions where the Tertiary formations out- crop. The asymmetry of the drainage is shown in the greater length of the secondary streams flowing into the Potomac as compared with the Patuxent tributaries. In Charles and St. Mary’s counties the streams on the Patuxtent River slope are very short and numerous as compared with the fewer, longer, and larger tributaries on the Potomac side, and in Calvert County the Chesapeake drainage slope receives the small streams while the Patuxent River the large ones. Thus the westerly-flowing streams seem to have been able to advance their headwaters faster than the ones flowing in the opposite direc- tion. In Prince George’s County the same conditions prevail, though in a much less exaggerated form. However, the sinuous divide between the Patuxent and Potomae drainage basins is readily seen to le adjacent to the Patuxent River. This asymmetry would be more marked were it not for the Western Branch, which extends its head so far from the parent stream. At the present time because of the tributaries of the Patuxent being shorter and more direct than those of the Potomac, erosion is more vigorous in the former basin than the latter, with the result that the divide is being pushed rapidly toward the Potomac River. Tide-water Hstuaries—The lower courses of almost all the larger streams emptying into Chesapeake Bay have been converted into estuaries through a submergence which has permitted tide water to pass up the former valleys of the streams. In the early development of the country these estuaries were of great value, as they are nav- igable for many miles from their mouths and thus afford means for ready transport of the produce of the region to market. Even the advent of railroads has not rendered them valueless and much grain and fruit are now shipped to market on steamers and small sailing vessels which traverse these estuaries. Chesapeake Bay and its tributary estuaries also furnish good fishing grounds, and during MARYLAND GEOLOGICAL SURVEY tuk: certain seasons they are frequented by wild waterfowl in such num- bers that they have long been known to sportsmen as among the finest hunting grounds in the country. The water in the estuaries is fresh or very slightly brackish, and ebbs and flows with the tide. There is seldom any distinct current to be noticed and such as is seen is due to the incoming or outgoing tide and appears to be nearly as strong when moving upstream as when moving in the opposite direction. The Potomac River.—The Potomac River is the most important stream to be mentioned in connection with the drainage of Prince George’s County. It forms about half of the western boundary of the County and receives, through its numerous tributaries the drain- age of about two-thirds of the area. The Potomac is an estuary up as far as Georgetown and is navigable almost to the head of tide water. Steamboats carrying freight and passengers ply between Washington and Chesapeake Bay ports, particularly Norfolk and Baltimore, though the modern high-draft war and ocean-going ves- sels cannot reach the city, and thus the Navy Yard at Washington ceases to fulfil the expectations of the founders of the capital. The estuary of the Potomac is from one-half to one mile in width along the borders of the County and gradually increases in width to about 13 miles at its mouth. The current is very slight and with the rising tide the water flows upstream. Almost the only rocks pres- ent are oceasional loose boulders which have been washed out of the Pleistocene deposits along the shores or have been transported from the Piedmont Plateau by floating ice. The banks are usually low though occasional bluffs of considerable height border the river. In this region the bluff on which Fort Washington stands is the highest and rises with very steep slopes over 100 feet above the water. At Georgetown the crystalline rocks pass beneath the water and this marks the head of tide water. Westward the stream gradient is much steeper, the river is narrower, the current is rapid, the bed of the stream is filled with boulders or ledges of rock, and the enclos- ing walls are of hard rock rising, in many places, almost perpen- dicularly from the water’s edge. THE PHYSIOGRAPHY OF PRINCE GEORGE'S COUNTY =| (0/8) The Potomac River receives many tributaries which drain por- tions of the county. Anacostia River, Oxon Run, Broad and Piscataway creeks, all of which are estuaries in their lower portions, are the most important. The heads of their estuaries are all being gradually filled by the materials brought down by their headwaters and by the accumulation of vegetable débris of marsh grasses which thrive in the shallow waters. Since the settlement of the region all of these streams have shown an appreciable amount of shoaling and navigation is now restricted to a very short distance from their junctions with the Potomac River. At present Anacostia River is not navigable above the bridge between the Navy Yard and Ana- costia, while Piscataway Creek is navigable as far up as Farmington Landing and that only at high tide. The Patuxent River.—The Patuxent River forms the boundary of Prince George’s County on the east and northeast sides. In most respects this stream is very much like the Potomac. Like it, it descends from the Piedmont Plateau as a rather swift-flowing stream in a rocky channel and quickly changes its character to a sluggish stream with banks of mud so soon as it enters the Coastal Plain. This change takes place at Laurel, where the crystalline rocks of the Piedmont Plateau disappear beneath the covering of uncon- solidated sediments. In the Patuxent River tide water does not extend up to the inner margin of the Coastal Plain as in the Potomac. The channel of that portion of Patuxent River bordering Prince George’s County is about 16 feet deep in the southern portion and shallows gradually to Leon, which is the head of steamboat naviga- tion. The river is bordered by marshy areas in many places through which the stream meanders in broad, open loops. Of the tributaries of the Patuxent River the Western Branch is the only one of any considerable importance. This stream drains a large area in the northern part of the County. Mataponi, Rock, Black Swamp, and Swanson creeks drain most of the southeastern portion of the County. MARYLAND GEOLOGICAL SURVEY 79 TOPOGRAPHIC HISTORY. The history of the development of the topography as it exists today is not complicated. The topographic features were formed at sev- eral different periods, during all of which the conditions must have been very similar. The physiographic record is merely the history of the development of the four plains already described as occupying different levels, and of the present drainage channels. The plains of Prince George’s County are primarily plains of deposition which, since their formation, have been more or less modified by the agencies of erosion. Their deposition and subsequent elevation to the heights SUNDERLAND ESS Fic. 1.—-Diagram showing ideal arrangement of the various terrace forma- tions in the Maryland Coastal Plain. at which they are now found indicate merely successive periods of depression and uplift. The drainage channels have throughout most of their courses undergone many changes; periods of cutting have been followed by periods of filling, and the present valleys and basins are the results of these opposing forces. The Lafayette Stage.-—Within the borders of the County there are evidences of frequent changes during Cretaceous and early Tertiary time which resulted in the deposition of a succession of formations composed of heterogeneous materials. ‘These changes, however, were to only a very slight extent influential in producing the present topography, so that in beginning the discussion of the physiographic history of the region they may be omitted. Toward the close of the Tertiary, however, a change in conditions occurred which is clearly shown in the existing topography. A layer of gravels, sands, and clays was spread over the entire Coastal Plain and along the borders of the Piedmont Plateau during the Lafayette submergence. These deposits, which, as already stated, must have been laid down on a SOQ THE PHYSIOGRAPHY OF PRINCE GEORGES COUNTY rather irregular surface, formed a thin mantle of materials, ranging from 25 to 50 feet in thickness. When the uphft which terminated Lafayette deposition occurred, a very even, gently sloping plain extending from the Piedmont Plateau to the ocean, bordered the continent. Across this plain, which was composed of coarse, uncon- solidated materials, streams rising in the Piedmont gradually extended their courses, while new ones confined to the Coastal Plain were also developed. At this time the shore line seems to have been farther east than now, and the present submerged channels of the continental shelf were probably then eroded. The Coastal Plain portions of Delaware River, with its extension Delaware Bay; Chesapeake Bay, which is the continuation of Susquehanna River ; and Potomac, Patuxent, Rappahannock, James, and other rivers date from this post-Lafayette uplift. The attitude of the subse- quent deposits makes this evident, for the Sunderland, Wicomico, Talbot, and Recent terrace formations all slope toward these various waterways. The Lafayette formation was cut through by the streams, and valleys were opened in the older deposits. Several of these valleys became many miles wide before the corrasive power of the streams was checked by the Sunderland submergence. The Sunderland Stage.—As the Coastal Plain was depressed, in early Pleistocene time, the ocean waters gradually extended up the river valleys and over the lower lying portions of the stream divides. The waves worked on the Lafayette-covered divides and removed the mantle of loose materials, which were either deposited farther out in the ocean or dropped in the estuaries formed by the drowning of the lower courses of the streams. Sea cliffs produced on points exposed to wave action were gradually pushed back as long as the sea continued to advance. ‘These cliffs are now represented by the escarpment separating the Sunderland from the Lafayette. The materials which the waves gathered from the shore, together with other materials brought in by the streams, were spread out in the estuaries and constitute the Sunderland formation. The tendency of the work done was to destroy all irregularities produced during the post-Lafayette erosion interval. In many places old stream courses were undoubtedly obliterated, but the MARYLAND GEOLOGICAL SURVEY. PRINCE GEORGE'S COUNTY, PLATE II. Fic. 1.—VIEW SHOWING INDURATED LEDGES OF THE PATUXENT FORMATION, W STREET, NEAR TWELITH STREET, WASHINGTON, D. C. Fic. 2.—vIEW SHOWING FLOODED IRON MINE IN THE ARUNDEL FORMATION NEAR MUIRKIRK. id =>, i - > Dats os - rare te. | Ge _ Ne > 7 7 Te MARYLAND GEOLOGICAL SURVEY Bult ( channels of the larger streams, although probably in some places entirely filled, were in the main left lower than the surrounding regions. Thus in the uplift following Sunderland deposition the larger streams reoccupied pragtically the same channels they had carved out in the preceding erosion period. They at once began to clear their channels and to widen their valleys, so that when the next submergence occurred the streams were eroding, as before, in Tertiary and Cretaceous materials. On the divides also the Sunder- land was gradually undermined and worn back. The Wicomico Stage-—When the Coastal Plain had been above water for a considerable time after the close of Sunderland deposi- tion a gradual submergence again occurred, so that the ocean waters once more encroached on the land. This submergence seems to have been about equal in amount throughout a large portion of the dis- trict, showing that the downward movement was without deforma- tion. The sea did not advance upon the land as far as it did during the previous submergence. At many places along the shore the waves cut cliffs into the deposits that had been laid down during the preceding epoch of deposition. Throughout many portions of the Coastal Plain at the present time these old sea cliffs are still preserved as escarpments, ranging from 10 to 15 feet in height. Where the waves were not sufficiently strong to enable them to cut cliffs it is somewhat difficult to locate the old shore line. During this time a large portion of Prince George’s County was submerged. The Sunderland deposits were largely destroyed by the advancing waves and redeposited over the floor of the Wicomico sea, although those portions which lay above 90 to 100 feet were for the most part preserved. Although the Wicomico submergence permitted the silting up of the submerged stream channels, yet the deposits were not thick enough to fill them entirely. Accordingly, in the uphft following Wicomico deposition the large streams reoccupied their former channels, with perhaps only slight changes. New streams were also developed and the Wicomico plain was more or less dissected along the water courses, the divides being at the same time gradually nar- rowed. This erosion period was interrupted by the Talbot sub- 82 THE PHYSIOGRAPHY OF PRINCE GEORGE'S COUNTY mergence, which carried part of the land beneath the sea and again drowned the lower courses of the streams. The Talbot Stage-—The Talbot deposition did not take place over so extensive an area as was covered by that of the Wicomico. It was confined to the old valleys and to the low stream divides, where the advancing waves destroyed the Wicomico deposits. The sea cliffs were pushed back as long as the waves advanced, and now stand as an escarpment that marks the boundaries of the Talbot sea and estuaries. This is the Talbot-Wicomico escarpment, previously described. At some places in the old stream channels the deposits were so thick that the streams in the succeeding period of elevation and erosion found it easier to excavate new courses than to follow the old ones. Generally, however, the streams reoccupied their former channels and renewed the corrasive work which had been interrupted by the Talbot submergence. As a result of this erosion the Talbot plain is now in many places rather uneven, yet it is more regular than the remnants of the Lafayette, Sunderland, and Wicomico plains, which have been subjected to denudation for a much longer period. The Recent Stage.—The land probably did not long remain stationary with respect to sea level before another downward move- ment began. This last subsidence is probably still in progress. Before it began the Patuxent and Potomac rivers, instead of being estuaries, were undoubtedly streams of varying importance lying above tide and emptying into a diminished Chesapeake Bay. Whether this movement will continue much longer can not, of course, be determined, but with respect to Delaware River there is sufficient evidence to show that it has been in progress within very recent time and undoubtedly still continues. Many square miles that had been land before this subsidence commenced are now beneath the waters of Chesapeake Bay and its estuaries, and are receiving deposits of mud and sand from the adjoining land. WHE GEOLOGY OF PRINCE GEORGE'S COUNTY BENJAMIN L. MILLER InrropucTORY. The geologic formations represented in Prince George’s County range in age from Archean to Recent. Deposition, however, has not been continuous and many gaps occur, that between the Archean and Cretaceous covering a very long interval of time. None of the larger geologic divisions since Jurassic time are entirely unrepresented. Periods when there was deposition over part or the whole of the region were separated by other periods of greater or less duration in which the entire region was above water and erosion was active. The deposits of all the periods except the Archean and Pleistocene are similar in many respects. With a general northeast-southwest strike and southeast dip, each formation disappears by passing under the next later one. In general also the shore line during each successive submergence evidently lay a short distance southeast of the position System. Series. Group. Formation. ( Talbot. Quaternary ..... | Pleistocene ......... Columbia ......)4 Wicomico. | {| Sunderland. | ( Pliocene (?) LN Me ne cA RS ab: Ge hyo) a Bs Lafayette. Tertiary ........ i MGIC ESE: Biniciocivee comes Chesapeake . ve ; canes ( Nanjemoy. ( Aquia. ( Monmouth. agate | Matawan. ‘ ee OHEIBCZOUS. ceallaoncosossochooc Magotlv: Cretaceous ...... 14 Hantian. | | ( Patapsco. | [Lower Cretaceous.... EQuomaecn esse: 4 Arundel. | | Patuxent. eT ees Tea ote erence 1S Silene eVell| seiereicis, pels. Suetsre? Dias Granite gneiss. | [BIOGEN GME e.g css crcvess a Pamunkey ..... IAT GHEAN. 2) of... secs 84 THE GEOLOGY OF PRINCE GEORGE $ COUNTY it occupied during the previous submergence. There are a few ex- ceptions to this, however, that will be noted in the descriptions which follow. The traveler passing from northwest to southeast crosses the outerops of the formations in the order of their deposition. The general sequence is shown in the accompanying table. THe Crystatiting Rocks. The exposures of crystalline rocks within the mits of Prince George’s County are confined to the deeper valleys along the northern border of the county. Elsewhere the erystallines are completely covered by the unconsolidated deposits of the Coastal Plain. Of the different varieties of rock developed in the contiguous portions of the Piedmont, only the granite gneiss and gabbro are exposed within the confines of the county. Granite gneiss, diorite, serpentine, eneisses, and schists are exposed within the District of Columbia and in near-by portions of Montgomery and Howard counties. The oldest rock of the region is the Baltimore gneiss, or Carolina eneiss, as it was earlier named by Keith in his description of the rocks of Washington and vicinity. According to Keith— “The formation is composed of alternating layers of gneiss and schist of a prevailing gray color, dark bluish gray where fresh, and greenish or yellowish gray where weathered. Individual bands vary from a few inches up to several feet in thickness, with an average of perhaps less than a foot . The original nature of the gneiss, whether igneous or sedimentary, is quite unknown.” GRANITE GNEISS. The granite gneiss is the first of three classes of granite which intruded the Baltimore gneiss and one of the two crystalline types found within the limits of the county. Like the gneiss, it is almost always gray in color, and the minerals have been arranged in approxi- mately parallel lines as a result of the metamorphism which the original granite suffered. There is, however, no true banding, as in the Baltimore gneiss, and the degree of schistosity varies from place to place. The black patches found in the granite gneiss are usually regarded as inclusions of Baltimore gneiss torn from the latter by the former at the time of intrusion. Outside the county, within the District and elsewhere, are other granites and diorites which might be confused with the latter, al- MARYLAND GEOLOGICAL SURVEY. PRINCE GEORGE'S COUNTY, PLATE III. Ee ES Es) pe Be] CENTIMETERS] VIEW SHOWING SILicirirp Cycap TruNK, Cycadeoidea marylandica (Fontaine), Cap. and Solms., FROM THE PATUXENT FORMATION OF PRINCE GEORGE'S COUNTY. oe Or MARYLAND GEOLOGICAL SURVEY though the granites are less schistose and the diorites show horn- blende more abundant than mica. GABBRO. Gabbro is the second type of crystalline rocks found within the county. It is exposed in the valley of the Patuxent near Laurel and has been quarried to some extent on the Howard County side, just above the Laurel bridge. When fresh and unmetamorphosed it is a dense bluish to greenish black rock of granular texture and extreme toughness. When metamorphosed it loses its granular tex- ture, becomes more and more platy through the development of fibrous hornblende and chlorite. When the gabbro weathers it forms rounded boulders with dark rusty surfaces, well known as “nigger heads.” he distribution of this type is usually marked by deep red and brown clay soils, which, though somewhat heavy, are strong and fertile. The crystalline rocks, as a complex unit, extend southeastward beneath the Coastal Plain, and serve as the basement on which rest the gravels, sands and clays which occupy practically all of the sur- face of the county. Tue Lower Cretaceous ForMATIONS. THE POTOMAC GROUP. The Potomac group of the Coastal Plain consists of highly colored gravels, sands, and clays which outcrop along a sinuous line from Pennsylvania to Richmond, passing near the cities of Philadelphia, Wilmington, Baltimore and Washington. The Potomac deposits are of great value because of the excellent brick clays which they contain. All three of the formations which are now recognized as composing this group are represented within Prince George’s County. The Patuxent Formation. The Patuxent formation received its name from Patuxent River, in the basin of which the deposits of this horizon were first recognized as an independent formation and systematically studied. Careful work showed that the deposits formerly included in the Potomac 86 THE GEOLOGY OF PRINCE GEORGE'S COUNTY formation were readily separable into distinct formations on the basis of unconformities and fossil content. Areal Distribution.—The area of outcrop of the Patuxent forma- tion extends from the mouth of Piscataway Creek up the west shore of the Potomac River to and beyond Anacostia River which, with its tributary, Indian Creek, constitutes for the most part the eastern boundary of the formation. It underlies the greater portion of the City of Washington and extends as almost continuous outcropping beds to Laurel. Character of Materials —The materials composing the Patuxent formation are extremely variable, although prevailingly arenaceous. Buff and light-colored sands, both fine and coarse, predominate, while beds and lenses of clays and gravels occur less commonly. The sandy strata, which usually contain considerable amounts of kaolinized feldspar and are therefore an arkose, were called by Rogers ‘“felds- pathic sandstone.” The sands are in many places cross-bedded, and with the gravels are here and there indurated by oxide of iron to form ferruginous sandstones. The sands contain small and large lenses of clay, which are commonly light in color, though locally they are highly colored by iron compounds. The following section exposed in the northwestern part of Wash- ington, is characteristic of the formation: Section in northwestern part of Washington, D. C. SUNDERLAND: Feet. VOC OBIS, F..c. coorarey roe focrster stole ehe an a ele Gerster cua aeRO Oren eneneRS 2 Stratinedseravelss sands: sand. claiySi scr ace rteieteenenels 2a PATUXENT: Coarse white arkosic pebbly sand, slightly lignitic; small pellets of white clay, and a lens of light greenish- drap sandy clay 5 feet in thickness. The strata show both horizontal and cross bedding. Amount exposed... 15 40 Paleontologic Character.—The organic remains of the Patuxent formation are neither plentiful nor varied. No animal remains have thus far been found in deposits of this age within Prince George’s County, but a teleost fish has been reported from beds of apparently the same age on James River in Virginia. Plant remains are equally rare and consist chiefly of the lgnitized and silicified trunks of oe io 2) ~~! MARYLAND GEOLOGICAL SURVEY conifers and cyeads. During the excavating for the new reservoir in Washington a silicified trunk 50 feet in length and several feet in diameter was found in beds belonging to the Patuxent formation. Another similar trunk about 4 feet in diameter was found in the vicinity of the Maryland Agricultural College. Strike, Dip and Thickness.—The strike of the Patuxent forma- tion in this county is almost due north and south along the Poto- mae River, but at Washington it changes to a northeast-southwest direction. The dip of the Patuxent, as well as of the overlying beds of the Potomac group in Maryland, ranges in direction from east-southeast in its more southerly exposures to south-southeast farther north. The normal dip of the basal beds of the formation reaches about 60 feet to the mile. In the vicinity of the ‘‘Fall line,” which is toward the landward margin of the Patuxent outcrop, the dip of the basal beds is considerably greater than this. Southeast of Washington it ranges from 50 to 75 feet, but near the “Fall line” it amounts to about 90 feet to the mile. The observed thickness ranges from a few feet to 340 feet, increas- ing toward the east. On the basis of well data the estimated maxi- mum thickness is about 500 feet. Stratigraphic Relations.—The Patuxent formation overlies the eranite-gneiss, of Archean age, and is overlain unconformably by the Arundel formation. In many places where the Arundel has been removed by erosion the Patuxent is overlain unconformably by clays, sands, and gravels belonging to the Columbia group. The Arundel Formation. The Arundel formation received its name from Anne Arundel County, where the deposits of this age are typically developed and well exposed. Areal Distribution.—The outcrops of the Arundel formation within Prince George’s County are confined entirely to its north- western portion between Washington and Laurel, but it is believed to underlie the greater portion of the county south and east of Anacostia 88 THE GEOLOGY OF PRINCE GEORGE'S COUNTY River. In its wider distribution the formation occupies a compara- tively narrow, irregular and much interrupted belt extending from Washington to Bush River, near the head of Chesapeake Bay. There are also outliers of less importance to the north and south of the general outerop. At Capitol Hill, Washington, a well boring, after passing through about 50 feet of Recent and Pleistocene materials, penetrated 131 feet of exceedingly tough drab and highly colored lignitie clays which apparently belong to the Arundel formation. Beneath these clays the boring passed into the Patuxent sands and gravels. Clays probably belonging to the Arundel formation were encountered in an excavation for a deep sewer in the vicinity of Anacostia bridge. Character of Materials—The materials composing the Arundel formation are diverse in lithologic character. They comprise large and small lenses of drab and iron-stained clays which in many places contain concretions, flakes or ledges of earthy iron carbonate and cellular limonite. Iron pyrite and gypsum occur Jess commonly. The clays may be either laminated, carrying more or less sand, or massive, with surfaces exhibiting slickensides. Logs of lignite, usually deposited in a horizontal position and greatly compressed, are found embedded within the formation. These logs are in places massed in well-detined beds of such thickness and extent as to be of local use to the miners for fuel. Occasionally large stumps are dis- covered standing buried in the position in which they grew, with the roots and trunks fossilized by iron carbonate and iron sulphide. Seeds of plants are found near some of these beds. Locally the clay is charged with comminuted lignite, when it is termed “charcoal clay” or “charcoal ore.” Here and there this “charcoal clay” con- tains fossil bones. Near Muirkirk, Hatcher obtained from it dinosaurian and other organic remains. Where the Arundel forma- tion has been exposed to the atmosphere the carbonate ores have at some places changed to the hydrous oxides of iron to a considerable depth. Where this has occurred, clays which were originally drab colored have become red or variegated. Along the western margin of the formation the materials become arenaceous and locally consist of lenses of sand. IV. PLATE NCE GEORGE'S COUNTY, PRI MARYLAND GEOLOGICAL SURVEY. ‘AZIS IWNOLVN SY4— (qT AoIe) “YSIVL snwau $nj9090LNIIq ‘KLNNOD S,ADIOUH AONTYG JO YAVSONIG SNOAOVIAND LSANOWWOD AHL dO NOLLVYOLSAY MARYLAND GEOLOGICAL SURVEY a) The section exposed at the Muirkirk iron mine, where the best dinosaurian remains thus far obtained from this formation were found, is as follows: Section at iron mine, Muirkirk, Mad. RECENT: Feet. Surface wash, consisting of loam and gravel........... 10 PATAPSCO: Sands and gravel, indurated in places by iron oxide and containing silicified trunks of conifers and cycads.... 10 Massive and stratified, mottled and variegated clays and sandy clays with redeposited nodules of iron carbon- ate and some limonite, pebbly at base, flanking the SHDLOMENAS NG” MINN NSPS So Sin gcucocan commoa tun dado > UDO COOCC 5 to 15 ARUNDEL: Massive blue clay with flakes and nodules of iron car- bonate and containing bones and teeth of dinosaurs RUMI LS Cee areca ecco tic he ecbate St alar shouoeti's 4, sc ahenetti anesthe: Brakes 20 to 40 Highly lignitic lens of clay (‘‘charcoal ore”’)........... 2 Tough blue clay containing iron carbonate............. 15 PATUXENT: Winite sands aAnrount exposed Tt wraps around the lower the heading “Topographic features.’ margin of the Wicomico terrace, from which it is separated in most places by a low escarpment. From the base of the Wicomico-Talbot scarp, Which is at an elevation of 40 to 45 feet, the surface of the Talbot formation slopes gently toward the surrounding waters. This surface has chiefly, if not entirely, the initial slope which was im- parted to it during its period of deposition. Usually this terrace is terminated by a low scarp cut by the waves of Chesapeake Bay or its estuaries, but locally it slopes gently to the water’s edge. The Talbot formation has suffered less erosion than either the Sunderland or the Wicomico. It has been elevated above the water for so short a time that such streams as have found their way across its surface have not been able to change materially its original level character. Paleontologic Character.—In the Maryland portion of the Coastal Plain there are a number of localities at which fossil remains of either plants or animals or both oceur in the Talbot deposits. The only specimen of animal remains found in the Talbot deposits of Prince George’s County consist of a bone of a mammoth determined by J. W. Gidley as the right humerus. It was found about 244 miles 126 THE GEOLOGY OF PRINCE GEORGE'S COUNTY northwest of Upper Marlboro at the road crossing of Cabin Branch near the Western Branch of the Patuxent River. It is now pre- served in the museum of Georgetown University. Near Cornfield Harbor, at the mouth of Potomac River, the formation has yielded a great number of mollusean shells representing a varied fauna of marine and brackish-water origin. Practically all the plants and animals are forms which still exist in this or other regions. Thickness.—The thickness of the Talbot formation is extremely variable, ranging from a few feet to 40 feet or more. The uneven- | ness of the surface upon which it was deposited has in part caused this variability. The proximity of certain regions to the mouths of streams during the Talbot submergence also accounts for the in- creased thickness of the formation in such areas. Stratigraphic Relations—The Talbot rests unconformably, in different portions of the region, upon various older formations belong- ing to the Cretaceous or Tertiary systems. It may in places rest upon deposits of Lafayette, Sunderland, or Wicomico age, although no positive evidence has yet been found to indicate such relations to the older Pleistocene formations. The deposits occupy a nearly horizontal position, having only a slight slope toward Chesapeake Bay and its estuaries. Tut Recent Deposits. In addition to the four terraces already discussed, a fifth is now being formed by the waters of the rivers and the waves of the estu- aries. This terrace is everywhere present along the water’s edge, extending from a few feet above tide to a few feet below. It is the youngest and topographically the lowest of the series. Normally it lies beneath and wraps about the margin of the Talbot terrace, from which it is separated by a low scarp that as a rule does not exceed 15 to 20 feet in height. Where the Talbot formation is absent, the Recent terrace may be found at the base of either of the other three terraces. In such places, however, the scarp which separates them is higher in proportion as the upper terrace is older. Peat, clay, MARYLAND GEOLOGICAL SURVEY Uy —l sand, and gravel make up the formation and these materials are de- posited in deltas, flood plains, beaches, bogs, dunes, bars, spits, and wave-built terraces. INTERPRETATION OF THE GEOLOGICAL RECORD. Almost all the formations which occur within Prince George’s County have a much more extensive development in the regions be- yond its borders. If study were confined to the area of this county alone many of the conclusions drawn from such investigations might be unsatisfactory and erroneous. The geologic history of the county, which is here outlined, has been based on work done not only in this area but also throughout the North Atlantic Coastal Plain from Raritan Bay to Potomae River and in certain localities in Virginia and the Carolinas. A study of the geologic history of the county shows that it has been long and complicated. This is indicated by the many different kinds of strata represented and by the relations which they bear to one another. There are deposits that were formed in fresh or brack- ish water; others that show evidence of their deposition in marine waters, some in water of shallow depth, others in deep water; while breaks in the conformity of the different strata indicate that from the time of the formation of the earliest beds down to the present day the region has undergone many elevations and subsidences. SEDIMENTARY RECORD OF THE CRYSTALLINE ROCKS. In this section rocks older than the Cretaceous are present only in the Piedmont Plateau. It is exceedingly difficult to interpret the past history of the Piedmont region for the reason that the whole area has been subjected to many great changes which have essentially modified the original materials; yet the studies of Williams, Keith, Mathews, Bascom, and others have revealed many facts concerning the original condition of the rocks now occupying this region. Nearly all the rocks of the Piedmont are metamorphic in character. Many of these rocks were originally sedimentary deposits, but in the processes of metamorphism have now lost nearly all traces of their 128 THE GEOLOGY OF PRINCE GEORGE'S COUNTY original character. Consequently it is scarcely possible to explain the conditions under which they were originally deposited. Yet it may be said that a large portion of the area which the Piedmont metamorphic rocks now occupy was under water at one time, or per- haps many times, and received in some places deposits of sand and mud carried in by streams, while in other places beds of limestone were formed. It is not known how long this sedimentation continued or how many breaks took place between successive periods of depo- sition. It has been thought by most recent workers in the Piedmont region that the rocks there include not only representatives of the Archean, to which most of the earlier geologists referred them, but of the Cambrian and Ordovician as well. These old rocks have been broken through in many different places by sheets and dikes of igneous material. Thus the Piedmont metamorphics comprise repre- sentatives of both igneous and sedimentary rocks. The structure of these rocks when first formed was undoubtedly much more simple than at present, but they have been repeatedly subjected to various processes of metamorphism by which the beds have been folded and erumpled and the original mineral composition has been greatly changed. There is no evidence to show a submergence of this area during the latter part of the Paleozoic era nor during the Triassic period. It probably remained as a land mass during most of this time, fur- nishing terrigenous materials to the Paleozoic sea to the west and to the Atlantic Ocean far to the east. It is of course possible that it may have been depressed beneath the ocean waters and covered with sediments many times, but, if so, later erosion has removed such de- posits from the crystalline surface. SEDIMENTARY RECORD OF THE LOWER CRETACEOUS. The earliest of the known unconsolidated deposits lying upon the floor of crystalline rocks belong to the Patuxent formation of the Potomac group. It indicates a submergence of the Coastal Plain in this region of sufficient extent to cover the whole area with shallow water. The cross-bedded sands and gravels furnish evidence of shift- MARYLAND GEOLOGICAL SURVEY 129 ing currents, as do also the abrupt changes in the character of the materials, both horizontally and vertically. The presence of numer- ous land plants in the clays shows the proximity of the land. The deposition of the Patuxent formation was ended by an uplift or warping in which many of the stream valleys were occupied for a portion of their courses by bogs and swamps of the Arundel formation. In these marshes there was an extensive development of plant life and in them also were deposited iron ores that are now of considerable value. After an uplift and interval of erosion the land was again depressed beneath sea level. Physical conditions similar to those which had prevailed during Patuxent time existed during this period of submergence, in which the Patapsco formation was laid down. Dicotyledonous plants, which are very rare and primitive in structure in the Patuxent deposits, are abundant in the Patapsco and belong to higher types. This seems to indicate that a long time intervened between the two periods of deposition, during which the land flora of the region materially changed. After the deposition of the Patapsco formation the region again became land through an upward movement which drained all the previously exist- ing estuaries and marshes. Erosion at once became active and the Patapsco surface was dissected. SEDIMENTARY RECORD OF THE UPPER CRETACEOUS. A downward land movement again submerged the greater portion of the region, leaving only a very narrow strip of Patapsco deposits above water. The Raritan formation was next deposited, under con- ditions very similar to those which had existed during the previous submergence. Raritan deposition was terminated by an uplift which again converted the entire region into land. The widespread development of shallow-water deposits, everywhere cross-bedded and extremely variable in lthologic character, and the presence throughout these deposits of land plants furnish some evi- dence that sedimentation took place not in open ocean waters but in brackish or fresh-water estuaries and marshes that were indirectly connected with the ocean, which may have at times locally 130 THE GEOLOGY OF PRINCE GEORGE'S COUNTY broken into the area. Some land barrier to the east of the present shore line probably existed and produced these conditions, but its position and extent can not be determined. The period during which the Magothy deposits were formed was one of transition from the estuarine or fresh-water conditions of Patapsco and Raritan time to the marine conditions under which the Matawan and Monmouth were laid down. The great variability in the lithologie character of the materials, the coarseness of the sands and gravels, and the cross-bedding all suggest conditions similar to those of the preceding periods. On the other hand, the local pockets of glauconitic sand and the presence of marine invertebrates sug- gest the marine conditions of the late Cretaceous. The probability is that over most of the area where Magothy deposits are now present Potomac conditions prevailed during the greater part of the period and in some places perhaps during the whole of it, but that ocea- sionally, through the breaking down of the land barriers which had kept out the ocean, there were incursions of sea water, bringing in marine forms of life. At the close of Magothy time the region was uplifted and a period of erosion was inaugurated. During this erosion interval compar- atively small amounts of material were removed. In some places it is impossible to establish definitely any stratigraphic break between the Magothy and the Matawan. This may be because the erosion interval was comparatively short or because the elevation of the land above the water was so slight that it did not permit the streams to cut channels in the recently formed deposits. Not until late Cretaceous time did a downward movement occur of sufficient extent to permit the ocean waters to transgress widely over this region. During the Matawan and Monmouth epochs prob- ably all of the county was beneath the ocean. The streams from the low-lying land evidently carried into the ocean at this time only small amounts of fine sand and mud, which afforded conditions favorable to the production of glauconite and permitted the accumu- lation of the greensand beds that are so characteristic of the Upper Cretaceous deposits along the Atlantic Coast. During this time very slight changes took place along the continental border, although MARYLAND GEOLOGICAL SURVEY HS elevation was probably proceeding slowly, as the Matawan and Mon- mouth formations are found outcropping farther and farther to the southeast. After the deposition of the Monmouth formation land movements again caused the shore line to retreat eastward, but to what point is not definitely known. Farther north, in New Jersey, deposition still continued in some places, for the Rancocas formation, which overlies the Monmouth formation and is not recognizable in the Maryland area, is there overlain by another and later deposit of Cretaceous age, the Manasquan formation. SEDIMENTARY RECORD OF THE EOCENE. At the close of the Cretaceous period the recently deposited sedi- ments were uplifted to form a land mass and sedimentation was suc- ceeded by erosion. In early Tertiary time a depression carried most of the region again beneath the waters of the ocean and the Kocene deposits were formed. The great amount of glauconite present in these formations indicates that the adjacent land mass must have been low and flat, so that the streams carried only small amounts of terrigenous material. The water in which this was dropped was doubtless only a few hundred fathoms deep, as glau- conite is not produced at great depths. The land-derived materials at the beginning of the Eocene consisted of small, well-rounded peb- bles which were deposited in several places in the region; but later the materials carried consisted of fine sand or clay. Many forms of animal life existed in these waters and their remains now com- pose layers of marl several feet in thickness. Studies of the fossils found in the Eocene deposits indicate that there were many changes in the fauna during this time. These changes were probably influenced to a greater or less extent by varia- tions in physical environment, yet the character of the deposits them- selves gives little evidence of such changes. Instead it seems that the conditions under which the Eocene deposits were produced were remarkably uniform, considering the great length of time which elapsed from the beginning to the close of the period. 132 , THE GEOLOGY OF PRINCE GEORGE'S COUNTY SEDIMENTARY RECORD OF THE MIOCENE. Hocene sedimentation was brought to a close by an uplift by which the shore line was carried far to the east and probably all of the present State of Maryland became land. This was followed by a resubmergence and another cycle was commenced. The deposits of the Miocene were laid down upon the land surface which had just been depressed beneath the water. Sluggish streams brought in fine sand and mud, which the waves and ocean currents spread over the sea bottom. Near the beginning of Miocene submergence, certain portions of the sea bottom received little or no materials from the land, and the water in those places was well suited as a habitat for diatoms. These must have lived in the waters in countless millions, and as they died their silicious shells fell to the bottom and produced the beds of diatomaceous or infusorial earth which are so common in the lower part of the Calvert formation. Many Protozoa as well as Mollusca lived in the same waters and their remains are plentifully distrib- uted throughout the deposits. During the Miocene epoch the condi- tions seem to have been favorable for animal life, as may be inferred from the great deposits of shell marl which were then formed. After the deposition of the Calvert formation the region was again raised and subjected to erosion for a short period, and then sank once more beneath the sea. The Choptank formation was laid down contemporaneously with the advancing ocean. This formation lies uncontormably upon the Calvert, and farther north transgresses it. In neighboring regions to the south of this county a third Miocene formation, the St. Mary’s, was deposited conformably upon the Chop- tank at a later period. SEDIMENTARY RECORD OF THE LAFAYETTE FORMATION. At the close of the Miocene the entire region was uplifted to form land. Streams at once began to carve valleys on the featureless sur- face. These conditions continued until the country was reduced approximately to a base-level, so that the weathered products of the Piedmont were not carried off by the sluggish streams. Then a sub- MARYLAND GEOLOGICAL SURVEY 133 sidence occurred which again brought the region under water. Coincident with the subsidence there seems to have been a slight ele- vation and tilting of the region west of the shore line. The heads of the streams were given renewed force, enabling them to carry down and spread over this region large quantities of gravel and sand, de- rived from the Piedmont and Paleozoic formations to the west. The evidence for the source of the material is found in many dif- ferent pebbles whose origin can be traced by their lithologie charac- ter or the fossils they contain. In the vicinity of Washington many of the gravel deposits contain fossils of Devonian and Carboniferous age brought from regions beyond the Blue Ridge. These fossils show that Potomac River had extended its drainage basin westward to those regions. During the submergence beneath the Lafayette sea, conditions were not uniform over the entire area, as gravel deposits were forming in some places at the same time that the clay beds were being deposited in others adjoining. Yet on the whole sedi- mentation was remarkably uniform throughout the area, considering the circumstances under which it took place. Over the former land surface a fairly persistent capping of gravel was deposited. But land movements were again taking place slowly. The velocity of the streams was checked so that gravel could no longer be carried down except in occasional freshets. Fine sand and loam were laid down over the gravel which had been previously deposited. This loam, which is so extensively developed over a large portion of Prince George’s County, marks the last period of Lafayette sedimentation. It marks also the last time that the entire region was submerged beneath the ocean waters. SEDIMENTARY RECORD OF THE PLEISTOCENE, At the close of the Pliocene epoch the region was raised again and extensively eroded, and was then lowered and received the de- posits which constitute the first member of the Columbia group. The Sunderland, Wicomico, and Talbot formations, which make up this group, are exposed as a series of terraces lying one above the other throughout the North Atlantic Coastal Plain from Raritan 134 THE GEOLOGY OF PRINCE GEORGE'S COUNTY Bay to Potomac River, as well as in Virginia and probably still farther south. The key to the solution of the relations existing be- tween the surficial deposits of Maryland lies almost exclusively in a correct correlation of these terraces. Much light may be thrown on this problem by a careful study of the Recent terrace now form- ing along the shores of the Atlantic Ocean and Chesapeake Bay and its tributaries. A discussion of this terrace is given below. After the close of the post-Lafayette erosion period the Coastal Plain was gradually lowered and the Sunderland sea advanced over the sinking region. The waves of this sea cut a scarp against the existing headlands of Lafayette and older rocks. This scarp was prominent in some places and obscure in others, but may be readily recognized in certain localities. As fast as the waves supplied the material, the shore and bottom currents swept it out to deeper water and deposited it so that the basal member of the Sunderland forma- tion, a mixture of clay, sand, and gravel, represents the work of shore currents along the advancing margin of the Sunderland sea; whereas the upper member, consisting of clay and loam, was depos- ited by quieter currents in deeper water after the shore line had advanced some distance westward and only the finer material found its way very far out. Ice-borne boulders are also scattered through the formation at all horizons. After the deposition of the Sunderland formation, the country was again elevated above ocean level and erosion began to tear away the Sunderland terrace. This elevation, however, was not of long dura- tion and the country eventually sank below the waves again. At this time the Wicomico sea repeated the work which had been done by the Sunderland sea except that it deposited its materials at a lower level and cut its scarp in the Sunderland formation. At this time also there was a contribution of ice-borne boulders which were depos- ited promiscuously over the bottom of the Wicomico sea. These are now found at many places embedded in the finer material of the Wicomico formation. At the close of Wicomico time the country was again elevated and eroded, and then lowered to receive the deposits of the Talbot sea. The geologic activities of Talbot time were a repetition of those car- MARYLAND GEOLOGICAL SURVEY 155) ried on during Sunderland and Wicomico time. The Talbot sea cut its scarp in the Wicomico formation, or in some places removed the Wicomico completely and cut into the Sunderland or still older deposits. Deposits were made on its terrace, a flat bench at the base of this escarpment. | Ice-borne boulders are also extremely com- mon in the Talbot formation, showing that blocks of ice charged with detritus from the land drifted out and deposited their load over the bottom of the Talbot sea. Embedded in the Talbot formation at many places there are lenses of drab-colored clay with plant remains. The stratigraphic rela- tions of the lenses of clay occurring in the Coastal Plain show that they are invariably unconformable with the underlying formation and apparently so with the overlying sand and loams belonging to the Talbot. This relationship was very puzzling until it appeared that the apparent unconformity with the Talbot, although in a sense real, does not, however, represent an appreciable lapse of time and that, consequently, the clay lenses are actually a part of that forma- tion. In brief, the clays carrying plant remains are regarded as lagoon deposits made in ponded stream channels and gradually buried beneath the advancing beach of the Talbot sea. The clays carrying marine and brackish-water organisms are believed to have been at first off-shore deposits made in moderately deep water, and later brackish-water deposits, formed behind a barrier beach and gradually buried by the advance of that beach toward the land. The last event in the geologic history of the region was a down- ward movement, which is still in progress. It is this which has produced the estuaries and tide-water marshes that form conspicuous features of the existing topography. At the present time the waves of the Atlantic Ocean and Chesapeake Bay are at work tearing away the land along their margins and depositing it on a subaqueous plat- form or terrace. This terrace is everywhere present in a more or less perfect state of development, and may be observed not only along the exposed shores, but also on passing up the estuaries to their heads. The materials which compose it are varied, depending both on the detritus directly surrendered by the land to the sea and on the cur- rents which sweep along the shore. On an unbroken coast the mate- 136 THE GEOLOGY OF PRINCE GEORGE'S COUNTY rial has a local character, while in the vicinity of a river mouth the terraces are composed of debris contributed from the entire river basin. Besides building a terrace, the waves of the ocean and bay are cutting a sea cliff along their coast line, the height of the cliff depend- ing not so much on the force of the breakers as on the relief of the land against which the waves beat. A low coast line yields a low sea cliff and a high coast line the reverse, and the one passes into the other as often and as abruptly as the topography changes, so that along the shore of Chesapeake Bay, high cliffs and low depressions occur in succession. In addition to these features, bars, spits, and other shore forma- tions of this character are being produced. If the present coast line were elevated slightly, the subaqueous platform which is now in process of building would appear as a well-defined terrace of variable width, with a surface either flat or gently sloping toward the water. This surface would everywhere fringe the shores of the ocean and bay, as well as those of the estuaries. The sea cliff would at first be sharp and easily distinguished, but with the lapse of time the less conspicuous portions would gradually yield to the leveling influences of erosion and might finally disappear altogether. Erosion would also destroy, in large measure, the continuity of the terrace, but as long as portions of it remained intact, the old surface could be recon- structed and the history of its origin determined. THE MINERAL RESOURCES OF PRINCE GEORGE'S COUNTY By BENJAMIN L. MILLER. INTRODUCTORY. The mineral resources of Prince George’s County are neither extensive nor especially valuable, but the county contains some deposits that are of considerable economic importance, although they have not hitherto been very largely worked. Among the most impor- tant are clays, sands, gravels, building stone, glauconitic and shell marls, diatomaceous earth, and iron ore. In addition the soils con- tribute much to the value of the region, which is primarily an agri- cultural one, and abundant supplies of water, readily obtainable in almost every portion of the county, form a further part of its mineral wealth. Tue NaruraL Deposits. THE CLAYS. Next to the soils the clays constitute the most valuable economic deposits of Prince George’s County. As already stated in the dis- cussion of the stratigraphy of the region, several of the formations contain considerable quantities of clay. These argillaceous beds are rather generally distributed throughout the county, but, so far as known, have in recent years been worked only in the vicinity of Washington. In colonial days bricks were made at a number of points throughout the region. The clays are found in each series of deposits represented in the region. For convenience they may be 138 THE MINERAL RESOURCES OF PRINCE GEORGE'S COUNTY discussed under the headings Cretaceous, Eocene and Miocene, and Lafayette and Pleistocene clays. Cretaceous Clays.—The clays of the Potomac group are the most valuable within the region under consideration. Each formation of the group contains deposits of clay that are suitable for a variety of uses. Some clays from the Patuxent have been employed for the manufacture of common brick, fire brick, and terra cotta; the Arun- del contains clays adapted to the manufacture of common brick, terra cotta, sewer pipes, and pottery; the Patapsco with its great variety of clays furnishes material suitable for the manufacture of common brick, fire brick, and other refractory ware, sewer pipes, and pottery; and the somewhat less argillaceous Raritan formation contains clays adapted to the manufacture of common brick, terra eotta, and fire brick. Eocene and Miocene Clays.—Although argillaceous beds occur very commonly in the Eocene and Miocene strata of the county, they are generally too sandy to be of much economic importance. Considerable lime, derived from the numerous fossil shells which are either generally distributed throughout the sandy clay or concen- trated in definite shell beds within the formations, also render these clays of less value. They are, however, very accessible, being exposed in the cliffs along the Patuxent River and in the valleys of tributary streams, and if a way of utilizing them should be discovered, they could be obtained in great quantities at little expense. The pink clay at the base of the Nanjemoy formation, known as the Marlboro clay, is the most valuable deposit of this group. It is about 25 feet thick and is exposed at many places in the stream valleys between Upper Marlboro and Piscataway. The clay is fairly plastic and no doubt could be used for making pressed brick, but is not plastic enough and is, besides, rather too sandy for pottery. Lafayette and Pleistocene Clays——As already stated, the Lafay- ette, Sunderland, Wicomico, and Talbot formations are generally composed of coarse materials at the base of the deposits, with a rather persistent loam cap which marks the last stage of deposition during each particular submergence. This surficial loam, which is very a_i MARYLAND GEOLOGICAL SURVEY 139 similar in all four formations, has been extensively used for the manufacture. of brick at many places in Virginia, the District of Columbia, Maryland, and southeastern Pennsylvania. It is gener- ally not more than 3 or 4 feet in thickness, yet, because of its posi- tion, many beds no more than 1 or 2 feet thick can be worked with profit. The loam is widely distributed throughout the county and, though not quite coextensive with the formations of which it forms a part, it is present in almost every locality where the Lafayette and Pleistocene formations occupy flat divides that have not suffered much erosion since their deposition. In general the surface loam is adapted only to the manufacture of the common varieties of brick and tile, but in some places it is suitable for making a fair quality of paving brick. In this region the surface loam from the Talbot and Wicomico formations has been utilized at several different times for the manufacture of brick in the eastern part of Washington, near Anacostia River. THE SANDS. Inasmuch as the arenaceous phase predominates in almost every Coastal Plain formation represented in the region, Prince George’s County contains an unlimited supply of sand. The sand of the Pleis- tocene and Lafayette formations is used locally for building purposes, but as it is so readily obtainable in all parts of the region no large pits have been opened. In some places the quartz sands of the Miocene seem to be pure enough for glass making, suggesting the Miocene glass sands so extensively exploited in southern New Jersey, although they have never been used in that way in this region. Careful chemical analy- ses and physical tests, which have not been made, would be required to determine their usefulness in this industry. The Magothy sands in the vicinity of Anacostia have long been worked and at present the most extensive sand pits of the region are opened in deposits of this age a short distance south of Anacostia. The sand is used for building and filtering purposes. In certain 140 THE MINERAL RESOURCES OF PRINCE GEORGES COUNTY places the Potomac deposits contain molding sand of fair grade, but it has not been used to any great extent. Locally the Lafayette and Pleistocene sands are rich in ferrugi- nous matter, which in some places cements the grains together, form- ing a ferruginous sandstone. Sands of this character possess a dis- tinct value for road-making purposes, as they pack readily and make a firm road bed. Where the material can be easily obtained in large quantities, good roads can be very economically constructed with it THE GRAVELS. The Pleistocene, Lafayette, and Potomac formations contain numerous beds of gravel widely distributed throughout the region. Those of the Pleistocene and Lafayette deposits are generally rich in iron, which acts as a cementing agent, thus rendering them of considerable value as-road metal. There are numerous gravel pits in the eastern part of the District of Columbia in deposits belonging to the Sunderland and Lafayette formations, and elsewhere in the vicinity of Washington there are smaller pits in deposits of Wicom- ico and Talbot age. THE BUILDING STONE. Prince George’s County contains few beds of building stone of much importance, yet in places materials occurring within the region have been used locally. The granite-gneiss is the best building stone of the region and furnishes good material for foundations and other rough work. It is schistose and consequently can not be obtained in large masses, but for that reason can be very easily quarried. Some of the more massive beds furnish stones suitable for building, and in places, where the beds are thinner and more micaceous, flagstones can be obtained. Although the Coastal Plain formations of the region are composed almost entirely of unconsolidated materials, yet locally indurated beds are not uncommon. In the absence of any better stone these indurated ledges furnish considerable material for the construction of foundations and walls. The best stone of this class is the firmly MARYLAND GEOLOGICAL SURVEY 141 cemented white sandstone occurring in the Raritan formation about 1 mile north of Collington. The shell beds of the Aquia in the vicinity of Upper Marlboro are so firmly consolidated that they furnish building stone, which though of poor grade is nevertheless suitable for rough work. The gravel bands of the Lafayette and Pleistocene are, in many places, so firmly cemented by iron oxide as to form pebble conglomerates of considerable strength. THE MARLS. Glauconite Marls.—The Eocene and Upper Cretaceous formations of the county are rich in deposits of glauconitic marls, which are of value as fertilizers. From New Jersey to North Carolina such deposits have been worked spasmodically since the early part of the last century, when their value was first determined, yet their impor- tance in enriching the soil has never been generally recognized. They consist of quartz sand with an admixture of many grains of glau- conite, a soft green mineral which is essentially a hydrous silicate of iron and potassium. On account of the glauconite, the marls are green in color and are commonly known as “‘greensand marls.” They are rich in calcium carbonate derived from the shells which are abundant in the deposits, and chemical analyses usually show the presence of small amounts of mineral phosphates. The marls thus contain three important plant foods—potash, lime, and phosphates. Altogether these constitute only a small percentage of the entire content of the deposits, yet wherever the marls can be obtained at low cost, they furnish economical means for increasing soil fertility. Where the glauconite marls have been used it is claimed that their beneficial effects is much more lasting than that obtained by means of artificial fertilizers. Within the county many Eocene and Upper Cretaceous beds rich in glauconite outcrop along the sides of the stream valleys, extending in a belt diagonally across the county from the Patuxent River to Mattawoman Creek. Shell Marls. tions also possess valuable fertilizing properties for soils deficient in The shell marls of the Miocene and Eocene forma- lime. In some places the shells are mixed with so much sand that 142 THE MINERAL RESOURCES OF PRINCE GEORGES COUNTY the lime forms only a small part of the deposit, but in others the amount of lime exceeds 90 per cent. Experiments show that better results have been obtained by the use of shell marl than by that of burned stone lime. The marl acts both chemically and physically and has a beneficial effect on both clayey and sandy soils. So far as known, the shell marls of this region have not been utilized, although they are well developed in many localities in the southern part of the county. THE DIATOMACEOUS EARTH. The principal workings of diatomaceous earth are at Lyons Creek, on the Anne Arundel side of the Patuxent River, although a bed of the material occurring at the base of the Calvert formation extends entirely across the southeastern portion of the county. Diatomaceous earth, on account of its porosity and compactness, is used in water filters and as an absorbent in the manufacture of dynamite. It is reduced readily to a fine powder and makes an excellent base for polishing compounds, while its nonconductivity of heat makes it a valuable ingredient in packing for steam boilers and pipes and in the manufacture of sates, the latter being the principal use to which it is put. It has been thought that this earth might be of use in certain branches of pottery manufacture which require refractory materials that have no color when burned. Heinrich Ries tested a sample of diatomaceous earth from Lyons Creek at cone 27 in the Deville furnace and found that the material fused to a drop of brownish glass. Its nonrefractory character is thus clearly demon- strated. THE IRON ORE. The Arundel formation in Maryland has long been known as the important iron-bearing member of the Potomac group and many mines have been worked in this formation in Prince George’s, Anne Arundel and Baltimore counties. In colonial times these mines were of the greatest importance and many of the cannon used in the Revo- lution were made from Potomac iron ores. In recent years, how- MARYLAND GEOLOGICAL SURVEY 1438 ever, these mines have decreased in importance, as most of them have been unable to compete with the Lake Superior ores and at the present time the only furnace using these ores is located at Muirkirk in the northern part of the county. The numerous immense pits now filled with water that can be seen in this region furnish evidence of the large quantity of ore that has been removed though the present opera- tions are rather small. The Muirkirk furnace has been in almost continuous use since 1847, and during that time has produced a great quantity of high- grade pig iron. After having been closed three years it was re- opened in May, 1909, and is now producing about 400 tons of pig iron per month from about 1,200 tons of ore. The ore is primarily an iron carbonate ore, though much of it has been altered to limonite or hematite near the surface. The oxidized ore is commonly called brown ore, while the carbonate ore is called white ore. The various stages of alteration can be readily seen in many specimens that have a shell of limonite or hematite with a central core of siderite. In other cases the alteration has affected the whole mass and no iron carbonate remains. The ore occurs in the form of flattened irregular nodules arranged in rather definite layers in compact plastic clay. In certain cases the nodules are in close contact and there is a persistent band of iron ore, but in other places considerable clay occurs between the ore masses. In most mines there are several layers of the iron ore separated by beds of clay of varying thickness. The ore layers are seldom more than 12 to 14 inches thick. Where the ore is mainly iron carbonate the color of the clay is generally buff to drab, but where the ore has been oxidized the clay is colored red and yellow. Considerable lignite is contained in the clays associated with the ore and, in places, the ore itself contains pieces of lignite. Such ore is usually discarded because of the iron pyrite which it is apt to con- tain. It is well known that lignite acts as a precipitating agent of iron sulphide carried in solution and it is not uncommon to find pieces of lignite coated with iron pyrite. The Arundel iron ore does not contain as high a percentage of iron as many of the iron ores used in this country, the average ore 144 THE MINERAL RESOURCES OF PRINCE GEORGES COUNTY running from 40% to 45% of metallic iron. Phosphorus and sulphur are unusually low, while manganese and silica are high. In one place a deposit of manganese ore has been found associated with the iron ore. The ore is mined in a very primitive manner, all the labor being done by hand, and the ore hauled direct to the furnace. The usual method of working is by open pits, but in some cases the ore is removed through slope tunnels and shallow shafts, where the cover- ing of barren clay is too thick to be profitably removed. In the tun- nels and shafts very little timbering is required. Practically no capital is necessary for this kind of mining and most of the men engaged in the operations are lessees who pay a royalty of about 35 cents per ton to the owner of the land. In most places the operators are able to make fair.wages, but no extensive mining can be done under these conditions. When the overburden becomes great the mine is abandoned and new openings made, so that it is not advisable to represent the working mines on the map. It is sufficient to say that they are all within a few miles of Muirkirk and Contee. At the furnace the ore is first roasted in order to eliminate any sulphur and also to convert the carbonate ore to the form of oxides. The pig iron produced at Muirkirk has long been known for its tensile strength, and for this reason commands a higher price than any other pig iron manufactured in this country. There is a ready market for the product, which is used exclusively in the manufacture of special articles in which great strength is required. It has been used extensively by the United States government in the manufac- ture of cannon and is also in demand for car wheels, cylinders and various special kinds of steel. The claim is made by the proprietors of the furnace that their product is the strongest pig iron produced in the United States. The slag has been used as road metal in the vicinity of Muirkirk, and at the present time is being shipped else- where for this purpose. THE PETROLEUM AND NATURAL GAS. Rumors have been circulated at various times of the discovery of petroleum and natural gas at several different places within the MARYLAND GEOLOGICAL SURVEY 145 county. Although many of these rumors have been without founda- tion, small amounts of oil and gas have been observed in some places during the sinking of wells and in the vicinity of streams where there is seepage from porous beds. The gases generated by decaying vegetation have been mistaken in certain cases for natural gas, and the iridescent film of limonite that often appears on the surface of stagnant water in swamps and bogs has been supposed to be petroleum. Borings have been made about 2 miles west of Annapolis in Anne Arundel County and about 1 mile south of Meadows in the search for oil and gas, but only traces were found. The Meadows well was sunk to a depth of 1511 feet, in all probability nearly to the erystal- line rocks, thus practically proving the absence in that place of any considerable amounts of either of these materials. It is not prob- able that either petroleum or natural gas in paying quantities will be found within the limits of the county. Tue WatTER RESOURCES. The water supply of Prince George’s County is found in the streams and wells of the district. Many of the streams have been used at various times to furnish power for small mills, but little use has been made of them as sources of water supply. Washington obtains its water supply at a point some distance beyond the western boundary of the county. Laurel draws its supply of water from a small tributary of the Patuxent River. With the exception of the residents of these two cities the inhabitants of the region derive their water supply from springs and wells. The wells are divided into two classes—shallow dug wells and deeper bored wells, the deeper usually furnishing artesian water. SPRINGS. The gently sloping strata, the alternation of porous and imper- vious beds, and the great amount of dissection by streams which the region has undergone, all contribute to the formation of springs along the valley slopes. From these springs many of the inhabitants obtain 146 THE MINERAL RESOURCES OF PRINCE GEORGE'S COUNTY their entire supply of water, which is usually of excellent character. The spring water, as also that in wells, is in places highly charged with mineral matter, particularly iron, sulphur, and salt, and some such waters have been placed on the market. The most important mineral springs of the county from which waters have been sold are the Bladensburg Spa at Bladensburg and the Algonquin Springs at Oxon. SHALLOW WELLS. Nearly all the water supply of the county is derived from shallow wells, varying in depth from 15 to 35 feet. The water is contained in the rather coarse sand or gravel bed so commonly forming the basal stratum of the Pleistocene and Lafayette deposits. So gen- erally is this the case that the depth of the shallow wells is usually a very good indication of the thickness of the surficial deposits. The surface water very readily penetrates the rather coarse surface materials until it reaches the less permeable underlying sedimentary or crystalline rocks. While some of it continues its downward course into these harder rocks a great deal flows along on their upper sur- face until it finds its way gradually into the streams. Hence wells sunk to this level are practically assured of a supply of water which, while seldom large in flow, is in seasons of average rainfall capable of furnishing sufficient water for ordinary purposes. Such shallow wells are necessarily dependent almost entirely on the amount of water which percolates through the Columbia and Lafayette deposits after rain storms, and are thus apt to be affected by droughts. After periods of heavy rainfall the water may rise in the wells within a few feet of the surface and then is very roily. At other times the wells may become dry, yet this does not often occur because of the fairly equable distribution of rainfall during the year. The supply is less variable over the broad divides or on level ground, where water is always nearer the surface, than in the regions of narrow stream divides, where the water finds an easy exit to the streams. In some places on the narrow divides in proximity to the major streams, it is necessary to sink wells to the depth of 100 feet or more in order to obtain a permanent supply of water. MARYLAND GEOLOGICAL SURVEY 147 Most of the water of the shallow wells is obtained at the base of the Lafayette or Sunderland deposits, as each of these formations covers large areas in which the streams have not yet cut through to the underlying deposits. There are also a number of shallow wells in the Patuxent River valley that derive their water supply from the base of the Talbot formation. The water of the shallow wells usually contains so little mineral matter in solution that it is known as soft water. In many wells, no doubt, it does contain organic matter, yet there is little evidence to show that the water on this account is unfit for drinking purposes. ARTESIAN WELLS. Since water is so readily procured at shallow depths in almost all sections of the county and few establishments in the region require a large supply, there have not been many attempts to obtain artesian water. The area in which wells may be driven with the expectation of discovering a pressure sufficient to force the water to the surface is restricted to land lying 20 feet or less above tide. In areas above this altitude pump wells can probably be had from the water-bearing strata enumerated in the succeeding paragraphs, the water rising under artesian pressure above the point where it enters the well, but not overflowing. The somewhat meager data obtained in this and adjoining regions indicate the occurrence of water at the horizons described in the following paragraphs: Waters of the Crystalline Rocks.—The waters contained in the crystalline rocks of the Piedmont Plateau are not of especial impor- tance in this region, since these rocks occur at or near the surface in a very small area. In the vicinity of Washington some wells obtain water from these rocks, but to the northwest of this county they yield an important water supply. In general water occurs at less definite horizons in the erystalline rocks than in the Coastal Plain deposits, and it is consequently much more difficult to predict the depth to which wells must be sunk to obtain a good supply. Beneath the unconsolidated sedimentary deposits of Prince George’s County crystalline rocks similar to those exposed at the 148 THE MINERAL RESOURCES OF PRINCE GEORGES COUNTY surface in the northwestern portion of the county undoubtedly occur. This underlying consolidated rock mass is frequently spoken of as “bed rock.” In general the crystalline rocks are less permeable than the overlying deposits and consequently check the downward passage of the percolating soil water, which tends to flow along on their surface or to collect in depressions. The surface of these old rocks dips rather uniformly to the southeast at an average rate of more than 100 feet to the mile. Along this crystalline floor much water flows to lower levels, and it therefore marks a good water horizon. Several artesian wells in the Coastal Plain derive an unfail- ing supply of pure water from this level. In Washington and the near vicinity water is obtained at this horizon in several wells, of which those at St. Elizabeth’s Asylum are the largest. Five of the six artesian wells that supply the water system of Hyattsville prob- ably obtain water at this horizon, which is reached at a depth of 250 feet. Though the water will overflow, the yield is increased by pump- ing. These five wells, together with another less than half as deep, are all pumped together and yield 130 gallons a minute. Throughout the greater portion of the county this crystalline floor can never be very important as a water horizon because of its great depth. It was not reached in a 1511-foot boring about 1 mile south of Meadows, and it is probable that it lies as much as 2000 feet below tide over a large portion of the county. Waters of the Lower Cretaceous Formations——The Potomac deposits contain many beds of coarse material that constitute good water-bearing strata. Some of these sand and gravel beds lie be- tween impervious deposits and thus furnish the requisite conditions for flowing artesian wells. Within the District of Columbia the beds belonging to the Potomac group are the principal water-bearing formations. The water does not seem to come from any one horizon of wide distribution, as is shown by the varying depths at which it is reached and by the failure to obtain any water in these beds at cer- tain places. Wells that were unsuccessful in finding a satisfactory supply of water were the 360-foot well at the ice works and the 133- foot well at the Mount Vernon apartment house. On the other hand, at Hyattsville and in the vicinity there are several wells with small MARYLAND GEOLOGICAL SURVEY 149 flow that derive their supply of water from Potomac strata at depths between 100 and 112 feet. At Bladensburg flowing wells with capacities ranging from 1 to 15 gallons a minute have been obtained at depths between 73 and 100 feet; at the plant of the National Capital Brewing Company there is a 103-foot well that yields from 100 to 130 gallons a minute; at Langdon a flow of 40 gallons a minute was obtained at a depth of 140 feet; at the Reform School water was encountered at a depth of 270 feet; and near Chesapeake Junction a well which formerly flowed but now has to be pumped obtains its supply of water at a depth of 350 feet. In adjoining regions the Potomac strata have yielded an abundant supply of water. At Annapolis, on the grounds of the United States Naval Academy, a well sunk to the depth of 601 feet penetrated eight water-bearing strata within the Potomac beds, from three of which water flowed out at the surface, 8 feet above tide. At the lowest horizon, between 587 and 601 feet, a flow of water of 75 gallons a minute is obtained. The water contains iron, but is of excellent quality when filtered. Waters of the Upper Cretaceous Formations.—The sandy strata of the Raritan and Magothy formations are in many places water-bear- ing. The water is apt to be strongly impregnated with iron, and locally with sulphur; consequently it is less desirable than that obtained from the Potomac deposits. At Upper Marlboro several flowing wells with an average depth of about 225 feet obtain a good supply of water from the Magothy. In some of the wells the amount of mineral matter in solution renders the water somewhat undesirable for drinking purposes, while in others the mineral matter seems to be present only in very small amounts. The Naval Academy well at Annapolis obtained flowing water from the Magothy at a depth between 180 and 220 feet, but as the supply was not sufficient the well was sunk deeper. In New Jersey considerable artesian water has been obtained from the greensand deposits of the Upper Cretaceous. In Prince George’s County no artesian wells are known in which the supply of water is obtained from the Matawan or Monmouth deposits. These are in general more porous than those of the Magothy or Potomac forma- 150 THE MINERAL RESOURCES OF PRINCE GEORGES COUNTY tions and contain fewer clay bands, so that the water passes more readily to lower levels. Waters of the Eocene Formations.—The character of the Eocene beds is in the main similar to that of the Upper Cretaceous. More clay members are present, however, and consequently conditions for flowing wells are more favorable. The water is almost everywhere heavily charged with iron, and sulphur is also present in places. In this county no flowing wells obtain their supply of water from Eocene strata, but in the adjoining counties, particularly along the Bay shore of Anne Arundel County, many flowing wells obtain moderate flows of fairly good water from horizons within both the Aquia and Nanjemoy formations. Waters of the Miocene Formations.—In the southern counties of the State, particularly in Calvert and St. Mary’s, important water- bearing strata of Miocene age have been found to yield an abundant supply of excellent artesian water. Within Prince George’s County, however, the Miocene strata lie so high that there is little head to the water contained in them, and flowing wells do not occur. Some shallow wells in the southern portion of the county probably derive their water supply from Calvert strata that in St. Mary’s County yield artesian water eke oOles OF PRINCE GEORGES COUNTY BY JAY A. BONSTERE: INTRODUCTORY. The relationship existing between the geology and the soils of any given area constitutes an important phase of the agricultural investi- gation of the region. ‘The influence exerted by the geology on the soils is of great importance in the theoretical consideration of the origin of the soils and of practical importance in determining the area, the characteristics, and the resources of each particular soil type. All of the geological formations of the world have been divided and sub-divided into formations and groups of formations in accord- ance with their sequence of deposition, as indicated by their relative positions with regard to one another and in accordance with the stage of development of fossil life forms that have been buried in the different layers. Since the basis of geological classification is one of age and of place relationships, while the fundamental] principle of soil classi- fication depends upon differences of soil texture, a given geological formation may give rise to two or more soil types. On the other hand, since the mineral composition and rock texture of different geological formations may closely resemble each other though their ages differ, so a single soil formation may be derived from two or more geological formations. Physiographic relations to stream drainage and to climate are also considered in the classification of the soils. Prince George’s County lies almost wholly within the Coastal Plain region of the State, though its extreme northern boundary slightly overlaps upon the Piedmont Plateau. Only a single soil type, the Cecil mica loam, is derived from the crystalline rocks of 152 THE SOILS OF PRINCE GEORGES COUNTY the latter region; all the other soils of the county are derived from the unconsolidated sediments belonging to the Mesozoic and Ceno- zoic portions of the geological column. Tuer Sor Types. The area of the several soil types occurring in Prince George’s County are given in the following table: AREAS OF DIFFERENT SOILS. Soil Acres | Per Cent. Peonardtowneloamene ee ereereen oe haere sere 45,770 14.9 Sisto ive Me Mmin ee) ah ellsac 4. oc +b ceoer Sete ne sss sc ogae 41,470 | 13.5 \yvannokere SeiGls saan ogacsds Se Pieets: Gish ee Nee 37,420 | 22 Wiest Alia Sal creci. cowtete seas ssl os ene ote 36,190 | TS IN IEE VGVON io. 3 HI EOI os GN oe RE eo earch 30,870 | 10.0 NomOlk gHiivels ooocadaoco- Eye waive iavan:. skere Rieter | 23,630 | Hath pOUime tonsa chy el OAM sreroarecti ister. oe. cicero | 23,260 | 7 6 Stisq ue Mamma, Clayen i. sje ante: Peirce se ee : 22,360 | 7.0 Susquehanna, clay, loam. 62 oct ere sis 055)-)s cme eae 16,850 5.5 INO TOD sel AINE fF cay eyo ayaa Meta accuses, «ces ado 9,660 Boll Sassairass! OAs shied alee eee rae eile ost Aemeee 9,090 3.0 Sassairasisandy loamiss.c:. sees os eos os bee Mae er 4,830 1.6 Leonardtown gravelly loam. ............... | 3,710 Moe ASE OMIM LE Nearetes feis ches 052, ch aco toro E NS cere! 6,38 ee me | 1,450 0.5 Cecilkimi cad Oar. oh.4 ale tabne ee tactic ce ee 600 0.2 gre aes en ee "207460 6 eee THE COLLINGTON SANDY LOAM. The Collington sandy loam comprises an area of nearly 36 square miles lying entirely within the “Forest of Prince George.” The MARYLAND GEOLOGICAL SURVEY 153 surface is gently rolling or nearly flat and lies at an elevation of from 80 to 160 feet above sea level. The original forest growth has been removed over this soil area, and with a very few exceptions the land is under a high state of cultivation. The usual staple crops of corn, wheat, and tobacco are cultivated upon this soil type. Wheat produces about 10 bushels and corn from 25 to 55 bushels per acre, while the tobacco raised is of good quality, yielding from 700 to over 1,000 pounds per acre. The Collington sand is derived through the natural process of weathering from the Aquia formation of the Eocene period. The material constituting this formation consists of the mineral glau- conite, a complex silicate of the bases potassium, calcium, mag- nesium, and ferrous iron, containing also some phosphoric acid. It is mixed with medium to coarse grained quartz sand. This mate- rial still remains unconsolidated, except for a narrow band of silice- ous rock only a few feet in thickness, which has very little influence upon the soil of the region. The Collington sandy loam as a soil type has been directly derived from the outcroppings of this greensand. Upon exposure to the weather the dark-green glauconitic material is affected chemically by the action of rain water and the impurities which it carries in solu- tion. The quartz grains contained in the greensand are only slightly dissolved during the chemical reactions which follow. On the other hand the glauconite, which is a very complex and unstable silicate, is altered in its chemical composition. Salts of potassium, magnesium, calcium, and iron are formed, and these, being soluble to different degrees, are unequally leached away by the circulation of the soil waters. The iron salts, in particular, frequently accumulate in the form of pipes, tubes, and irregular concretions of hydrated carbonate of iron, binding together grains of quartz sand. These pipes are fre- quently filled with unweathered or partly weathered glauconite. Glauconite, as is the case with the greater number of minerals, 1s a salt, but a very complex one, containing, as stated above, potassium, ferrous iron, calcium, and magnesium as bases, the bivalent elements replacing each other in somewhat indeterminate quantities. The 154 THE SOILS OF PRINCE GEORGES COUNTY complex silicic acid is very weak as compared with the bases. Although the mineral itself, perhaps, does not possess a large solu- bility, in as far as it is soluble at all it will be dissociated and greatly hydrolized.* The result will be the formation of large quantities of hydrates of potassium, calcium, and magnesium, which will in turn be converted to the corresponding carbonates, or, more probably, hydrogen carbonates, better known as bicarbonates, through the absorption of and combination with the carbon dioxide contained in considerable quantities in the atmosphere of all soils. The ferrous iron will also be largely converted into the hydrate by the hydrolytic action of the water. But it will be further acted upon by both the oxygen and carbon dioxide in the soil atmosphere, so that the final product which it yields will be a more or less highly carbonated ferric hydrate, and it is this material which forms the cement of the pipes described above. As the analyses show, this glauconitic material is unusually rich in potassium. Analyses are given in the following table of a greensand marl obtained from an outerop of the fresh material near Upper Marlboro, in Maryland, as well as of two soils and three subsoils. The method of analysis chosen was the official one of the Association of Official Agricultural Chemists—that is, the digestion in concentrated hydro- chloric acid of specific gravity 1.115. This method was selected principally because it would enable the results obtained on these samples to be compared with those of other agricultural chemists, and probably it furnishes as clear an idea as any other method would of the agricultural values of the samples. It may be said in general that the results of this chemical exami- nation show the chief value of the greensand marls of Maryland to be due to the potash they contain, and which they slowly release as they dissolve and break down in the process of weathering. To a much less extent probably are they of value for their content of lime and phosphoric acid. In this latter respect they do not compare favorably with the similar marl deposits of New Jersey and some other regions, which, while valuable for the potash they contain, are more so on account of the very large content of phosphoric acid and ~1For a general discussion of this subject the reader is referred to Bull. 17, Division of Soils, U. S. Department of Agriculture, 1901. MARYLAND GEOLOGICAL SURVEY Abs 5) soluble lime. It is probable that the New Jersey greensand marls would on the average have a phosphoric acid content fifty times as great as the corresponding marls from Maryland. It is, therefore, very questionable whether many of the greensand marls of Mary- land can have any important economic future as a fertilizer when compared with other products now on the market. CHEMICAL ANALYSES OF GREENSAND AND CoLLINGTON SANDY LOAM, 6034.* 5454.+ | 5455.4 5456.§ 5459.° | 5460.°° Constituent. | Per cent.|Per cent. Per cent. Per cent. Per cent. Per cent. —_ : a : Patel (1K (O))s0cbo te vapeenne 2.565 | 0 858 | 0.888 | 0.440 | 0.910 | 0.576 | | | | Soda (Na,O) ...------------ BO 980 718 | 2.401)" ) 2285 .692 | Litt (OHO))oc onssccvcadsoues dO) ee en £0) | plone eeek) . 155 -210 | Magnesia (MgO)..--.+---+-+: | 740 136 396 74) .185 336 : | i Manganese oxide (MnQ)....- oso zeie ate | 037 EOSON rcistetecerele 035 037 Troma(Hen),)scje cee Hace 16.306 | 9.488| 4.011] 9.067 | 3.632] 6.248 | PMlnrmimai(C Als Og) '- 224+ sone 130 | 4.011| 2.448] 4.097| 2.856) 4.742 Phosphoric acid (P,0;) .---- 065 .088 | .054 .104 | .053 076 Sulphurie acid (SO,)......-- (O12 emis? | e116 | 2006s) tp | 056 | Imsolubles -.. ...- Hy eB OMI THESES) ooo pau I Siacas 4. Mall epetonerabarttay| pate agate ate see WICKER poco ao eeeasoseneaces DAS el oretne. een pertiae Ie foresee arte ate inion ons io Volatile organic matter......- WSs) so woe coulonceocss \ieaiaes oo ti |e 2 En ects *Greensand deposit, Upper Marlboro, Md. is ~~ §Subsoil of 5455, 7 to 36 inches. +Subsoil, 8 to 36 inches, Oak Grove, Md. °Soil, 0 to 9 inches, Mullikin, Md. tSoil, 0 to 7 inches, Mullikin, Md. °°Subsoil of 5459, 9 to 36 inches. An inspection of the table will show that the soils and subsoils derived from glauconitic material are rich in potassium, as compared with agricultural soils in general, although a proportionally large amount of this element disappears in the weathering process during soil formation. On the other hand, neither the lime nor phosphoric acid content of these soils is materially different from that of the original material and both are lower than is considered desirable for good soils. The indications of this examination are that these soils 156 THE SOILS OF PRINCE GEORGES COUNTY are lacking in lime, phosphoric acid, and humus, and efforts to improve them in these respects are desirable. In the field the results of the chemical processes of weathering are shown by nearly every soil boring taken within the area of the Col- lington sandy loam. The surface soil, which has a depth varying from 9 to 20 inches under different conditions of cultivation, con- sists of a loose, loamy, brown sand, usually containing considerable coarse sand and small amounts of intermediate grades of soil par- ticles down to silt and clay. The loamy nature differs from that of ordinary soils in the fact that the rather coarse materials are bound together by much finer materials, which are sticky rather than plastic. Even this fine material when dry crumbles easily to the touch into a powdery brown mass. The immediate subsoil differs from the soil in texture and composition. The glauconite is passing through intermediate stages of weathering, and has been sufficiently transformed to constitute a sticky, claylike mass, in which dark- green specks of glauconite can still be distinguished. The partly weathered glauconite includes a considerable percentage of quartz sand within its mass. The hydration of the iron salts produces a yellowish or greenish-yellow color in the subsoil. Usually at a depth of 30 to 40 inches the greensand can be found in almost its original state of purity. It has been much less attacked by the processes of weathering than either the soil or the immediate subsoil. It still maintains a considerable supply of potash, phosphoric acid and lime—three plant foods commonly purchased at considerable expense in the form of commercial fertilizers. The presence of this plant food underneath the soil is manifested by the general productivity of the entire area of the Collington sandy loam. In the Prince George’s area this greensand marl, which occurs along the numerous stream cuttings and natural cliffs, has only been used to a slight extent as a source of fertilizer. In one case, it is said, its copious application over an already sandy soil produced a crop of wheat averaging 25 bushels per acre, and its effect was noticed in several succeeding crops. In other areas, both in the United States and foreign countries, the greensand marl has long been utilized as an inexpensive though effective medium for restoring impoverished MARYLAND GEOLOGICAL SURVEY 157 soils. Its application upon heavy loam or clay lands should be par- ticularly beneficial, since the sandy nature of this marl would improve the texture of the soil while its chemical elements supplied essential plant foods. The Collington sandy loam is justly recognized as a good soil for general farming operations, but its adaptability to special crops is only partly realized. Tt is an area excellently adapted to market gardening and medium and late truck crops. It produces fruits of excellent quality and its special adaptation to the production of nursery stock is already utilized. It should also furnish excellent crops for canning factory purposes. The present system of general farming practiced on this soil type should give place to a much more specialized type of agriculture, accompanied by a decrease in the average size of the land holdings and by much greater profits per acre. The following table gives mechanical analyses of typical samples of soils and subsoils of Collington sandy loam: MECHANICAL ANALYSES OF COLLINGTON SANDY LOAM. ay g 1D 4 ° ; coal 5 st flee Sg aie ) A S pared A o Sell scales B is 2 | o eg! SS. late eg eens he Soe a : ai ee = | = itv erin ti sey |r bs g os No. Locality. Description. 2 Ss 3 z : ; 5 | Big | 3 | 9 5 | eos 3 a & 25 euisiey| = | 24 a o 5 i a oS | = 5 Bd me | = a : =r =, mH ra o > = | \[nee z s | 3 Bs 5 = | a | 9 oO S) | m - mn | 0 = {P-et/P.ct.|P.ct.|P. ct. (Pict. Bet Eau P. ct. 5457/14 miles SW. ofMedium, loosel.70| Tr. 4.5210.3459. 1810.10 7.22 5.10 Woodmoor, Md. green sand, 0 to | | | | 11 inches. | 4, 24/83 .94111 .14/36.52) 8.08 5459/Mullikin, Md... Fine, mealy sand, 4.78)0.001.10 | 0 to 9 inches. | | 5451 Oakgrove, Md... Loose, fine greenish 1.92} Tr. 1.94 9.0450.1216.76 9.5410.74 | sand,0to7 inches. 545514 miles SE. of Fine glauconite4.420.002.38 6.1654.6416.96 4.2210.96 _ Mullikin, Md... sand,0to7 inches. | 5458 Subsoil of 5457.. Medium glauconite 1.86) Tr. 6.8616.44/48.50 5.38 8.4012.26 | sand, sticky, 11 to | | 36 inches. | | 5460 Subsoil of 5459.. Fine to me dium2.300.00 Tr. 5.18/383.6217.1020.7020.68 | sand,9 to 36 inches, | | | | : - Glauconite sand, 2.92/0.002.84 6.7646.22)14.72 6.7819.92 I streky.. 7 to 36 | | | | | 5452\Subsoil of 5451 inches. | | Heavy sand, rather 2.820.002.44 5.1450.2613.52 4.9221.16 sticky, 7 to 36 inches. 5456Subsoil of 5455 158 THE NORFOLK SAND. THE SOILS OF PRINCE GEORGE'S COUNTY The Norfolk sand occupies a total area of 23,630 acres in Prince flat-topped terraces along the larger stream courses, and caps the highest hills in the northern cen- George’s County. tral portion of the county. It covers low-lying, It is derived from various sandy strata found in the Coastal Plain portion of Maryland, either by the direct weathering of the outcrops or by stream erosion, transportation, and redeposition in other localitie Ss. The accompanying analyses exhibit the sandy nature of this soil: MECHANICAL ANALYSES OF NORFOLK SAND. lez |: ge |x ge |s eae | |os c g x ° ) ioe en eI oO ~ |e 2 eo ° us | uo a} 3 co, No Locality. Description. |v ste [ie | ie od == -| Sea |} = ag | % 2 & z a | S a |= & | do 3 S cS) |S =I Ls o 2 [2 ° o iS) = P.ct. P.ct.P.ct. P.ct. P. ct. 5487 2 miles NW. of Coarse sand, truck0.010.800.00 7.5634.78 Priest Bridge. soil, 0 to9 inches., | | | | | | 5485 2 miles NE. of Medium fine yel- .01 1.902 .1011.78)24.54 | Bowie. | low sand, 0 to 10 | | inches. 54894 mile N. of Brown sand, 0to 7 .013.009.08 23 .62/19.50 Hyattsville. inches. | | | | 5488 Subsoil of 5487. Coarse yellow sand, -010.60)0.00 7.5642.64 | 9to40 inches. | | mea: | : eater | 5486 Subsoil of 5485. eee sand, 10) -011.90, Tr. | 8.98/22.56 30 inches. | | | | | | | | 5490 Subsoil of 5489. Loamy red sand, 7 -032.568.5022.6413.16 | to 36 inches. The uncleared areas of | growths of pitch pine and several varieties of oak. of the area occupied by this soil type is cleared and utilized in gen- eral farming or truck growing. O:1 to mm. 0.05 mm. Fine sand, 0.25 to 0.1 Very fine sand, Pact. 37.86 ° Sia o > oS (op) (Jw) rss oz. 12 13.76| 7 . 32 16 31.50 18.56) Or —s e2) Silt, 0.05 to 0.005 mm. Pict: 13. 40 0.005 to 0.0001 Clay, 32) 60 Norfolk sand are oceupied by forest A large portion MARYLAND GEOLOGICAL SURVEY 159 The terrace areas are flat-topped or only gently inclined, while those areas derived from the outcrop of older strata are rolling or gently inclined. The soil consists of a medium to coarse orange or yellow sand, having a depth of about 10 inches. It is underlain by a coarse sandy subsoil which usually becomes loamy at a depth of about 3 feet. The loose, open character of this soil prevents it from maintaining a large water supply, and thus precludes the successful production of such crops as require a long growing season. This soil is especially adapted to the production of early truck crops, which can be forced to an early maturity and prepared for a profitable market. This soil is largely utilized for trucking and mar- ket gardening along the Atlantic seaboard. Early strawberries, mel- ons, potatoes, and sweet potatoes can all be raised with profit, while small crops of high-grade tobacco can also be produced. The soil requires careful treatment under highly specialized condi- tions of farm practice. It requires the incorporation of large amounts of organic matter in order to produce the best results. The plowing under of leguminous crops and the addition of stable manure improve the texture of the soil. THE WESTPHALIA SAND. The Westphalia sand occupies the gently sloping valley walls and the low, rolling hilly areas of eastern Prince George’s County. The type is derived from the weathering of the surface outcrops of several sandy geological formations. Small areas of Westphalia sand near Buena Vista are derived from the loamy micaceous sands of the Matawan, but the greater number of the areas are derived from the clayey, somewhat glauconitic sands of the Nanjemoy formation. In the southwestern part of the county the sandier upper portions of the Calvert also give rise to Westphalia sand areas. These lie as low hills along the slope to the Patuxent River, and the soil type here attains its greatest agricultural value. The natural forest growth of this soil includes oak, sycamore, tulip, and chestnut. No large forest areas exist, but scattered clumps of trees abound. 160 THE SOILS OF PRINCE GEORGES COUNTY The soil consists of a fine sand or slightly loamy sand, yellow in color and friable and powdery when dry, but slightly sticky and easily compacted when wet. It is underlain at a depth of 9 to 16 inches by a loamy, fine-grained sand, slightly more cohesive and sticky. This is sometimes succeeded by loose gray sand, but not universally. The accompanying table shows the texture of this type: MECHANICAL ANALYSES OF WESTPHALIA SAND. | | | wa le | g |x = £ a PS sé |e Steed z | ea le | A es toe id EIS : > lo s z | De Meee ies piece hs 2 |S go jag] & ° oo Ye) es S } | g = || Pu} < oa 2 = | | u = | nl °S le |b Les 5 g So > No. | alate areas na pF 5 c | o | =I No. Locality. Description. Fac Pe S 3 z 3 ‘ F a S 98 | eel ca| oe eee eae eee | ooF| 2B] g 3 a | 5 | Oe) ey eri : (ag als | el) es 7c 2 Ds ray Pe jy Es) Eo eles Gi iS ® =I = | Se | .S) = & - mn o | | aay (ee Rae | | lP.ct. P.ct.|P.ct.| P.ct. | P.ct.| P.ct. | P.ct.| P.ct.| P.ct. | cs z - a n a1 Kp > 6 5475/1 mile S. offVery fine, mealy0.01|2.440.00 Tr. | 0.7014.4256.04/17.00 8.29 Marlboro. yellow sand 0 to | | | | 10 inches. 5477/2 miles N. of|Fine, mealy brown- .01/2.52 Tr. | 1.50) 1.9417. 22'44.40123.20) 9.21 Marlboro. ish sand, 0 to 10 | | inches. | | 5479/2 miles S. of|Fine, mealy yellow) .01/3.14 .00 .00 2.8224.9834.7419.80153.49 Aquasco. sand, 0 to 12 | inches. .1865.50)20.22 5.13 =] 5476)Subsoil of 5475)Very fine mealy .01/1.92 .00 .00 Tr. | sand, 10 to 30 | inches. ~J bo bo Or 5480 Subsoil of 5479 Fine, sticky sand, .01|2.86 .00 00 1.1410.08 48.7225. 6010.67 12 to 56 Inches. | | | 5478 Subsoil of 5477 Fine to sticky sand, .01/2.14 Tr. 2.22 2.5622.2341.38/15.3214.63 10 to 30 inches. | | The Westphalia sand is finer-grained, less porous, and less friable than the Norfolk sand. It is well adapted to the production of the Maryland type of export tobacco, especially where its surface is level or only gently sloping. On the steeper slopes it is liable to be washed destructively. It is also a good producer of Irish potatoes and corn. MARYLAND GEOLOGICAL SURVEY 161 Though somewhat loamy, its water-holding capacity is not sufficient to constitute it a desirable grass or grain soil. These crops are culti- vated in the regular crop rotation, but without securing profitable yields. Peaches, small fruits, strawberries, and melons could be raised to advantage on this soil type, and its physical properties fit it for the production of these and later truck crops. It could not com- pete with the Norfolk sand in the production of early truck. The smaller areas of Westphalia sand, especially those lying on the steeper slopes, are not well adapted to agricultural purposes. The removal of the surface soil is so rapid that underlying material is not prepared for crop production by weathering with enough rapidity to maintain annual crops. Such areas should become orchard lands or should be reforested. THE WINDSOR SAND. This type of soil, which is found in many other localities along the Atlantic Coast, occupies an area of about 58 square miles, chiefly in the upland area of central and southern Prince George’s County. Tt is usually found along the gently sloping valleys of streams or where the headwaters of two drainage systems approach each other. The surface is thus gently sloping or more steeply inclined, with the change of circumstances of stream erosion. This soil in its natural condition is the one most preferred by the pitch pine, and the extensive forests of this tree found on the Windsor sand have led to its being called ‘‘pine barrens” in some localities. This name is misleading, for although unsuited to the production of grain and grass crops, the Windsor sand constitutes a type of soil adapted to early truck crops, to fine early peaches, and, under favor- able climatic conditions, to fine grades of tobacco. The Windsor sand consists of a medium to coarse sandy soil that contains about 10 per cent of fine gravel. The soil is loose and friable and very unretentive of moisture. It reaches to the depth of about 8 or 10 inches and is underlain by a coarse sandy subsoil, which dif- fers from the soil chiefly in its smaller content of organic matter. The depth of the subsoil depends largely upon the location of the area. The higher-lying, flatter areas have the deeper and sandier sub- 162 THE SOILS OF PRINCE GEORGES COUNTY soils, and are more typically developed. The areas along the stream slopes, being subject to wash from above and also themselves arising from local soil creep and migration, are more irregular in texture and are usually of a less depth. The Windsor sand also occurs along the Patuxent River and some of the other larger streams as a low-lying flat-topped stream terrace. The soil texture is the same as that of the upland areas, and the vege- tation and crop value are closely similar, but the position near tide level gives an advantage to the areas in two ways. In the first place, the products of the area are nearer to water transportation. In the second place, many of the areas are so situated that whenever it becomes desirable the waters of upland streams can be turned upon them for irrigation purposes. The Windsor sand produces a good grade of tobacco in several regions where it occurs, but it is uncertain, from the fact that its loose, porous character makes it particularly hard to manage during a protracted drought. The same difficulty is encountered in the pro- duction of truck crops. For this reason an intensive system of culti- vation is required, including the incorporation of considerable amounts of organic matter with the soil to form a spongy, moisture- holding mass, as well as to furnish needed plant foods. When, in addition, it is possible to irrigate, and the value of crops produced is sufficient to warrant it, the water supply can be controlled and a crop produced every year instead of once in two or three years. As yet the conditions are not such as would warrant so expensive a treatment in the Prince George’s areas, but many of them can be irrigated when it becomes desirable to do so. The texture of this soil and subsoil is shown by the accompanying table. THE SUSQUEHANNA GRAVEL. Scattered areas and long, narrow bands of distinctly stony or gravelly soil have been indicated as a special type. The different areas are usually found along steeply inclined slopes or near stream divides. In both cases active stream erosion has removed the surface MARYLAND GEOLOGICAL SURVEY 163 covering, consisting of other soils, and the heavy gravel bands which underlie several of the upland soil types are thus exposed. The natural timber growth of these gravelly areas consists of chest- nut, pine, and oak, while the cultivated crops are usually the same as those found on better soils. Where a single narrow gravel band crosses a cultivated field no difference is made in the adaptation of MECHANICAL ANALYSES OF WINDSOR SAND. [Fine earth.] ae la | gh salir iS n= So 5 S| é =) & = sais 5 s q = os a) o — a = TS = «i I 1S ° ° : = =| eee =I } > ~~ i) ex) > ny eta E > = S ao 2 | ° 12 = S = = ~ 35 : ats | é =) BS las a Be aS . Oy bey le S | ; Peps eo WEE t ee logis Pee es No. Locality. Description. ees ° as =| Slee ey Phen! ate} AGics) || oe E es -— | im hoa a 4) 980 a 3 Zi =) ai Ne) > na Hat lI n | = xO S = oom Ea i S S | g =6 = 2 o iS | i=, 2525 > ea th = F ler = =i = b= = is So 2 ae) 3 = a | @ & = Snes 7) | O ids oO | = & - a o rz 5 | Pict Prct:evet. Pict. ||P. cts i>. ct. peacta /Pactaeets 55113 miles NE. of Coarse sand, 0 to 90.01/0.72)11.92/40.36)21.50/11.38) 2.86, 7.483.09 Bowie. inches. | 55091 mile S. ofCoarse sand and! .01) .94 9.1823.36/19.10/17.42) 7.3615.284.: Queen Anne.| gravel, 0 to 8 | | | inches. | | | | 5512 Subsoil of 5511. Coarse sand and) .01j1.1211.3635.38)21.9013.36 4.82 7.683.65 | gravel, 9 to 24! | | | | | inches. | | 1 ~I 5510 Subsoil of 5509. Coarse sand and) .011.54) 9.3024.76/21.42115.18 5.06114.687. ‘ | | gravel, 8 to 30 | | inches. | | crop to this exceptionally gravelly condition, although the yield of the crop is invariably much less than upon the other soil. Where the larger areas are found, the Susquehanna gravel if cleared should be reforested, not only because of its small value as farm land, but also to prevent further washing and destruction of adjoining areas of more valuable soil. The Susquehanna gravel consists of 30 to 60 per cent. of coarse gravel mixed with sand and loam. It is underlain by various sub- soils, usually loamy or sandy. In addition to presenting great diffi- culties in the way of cultivation, it is unsuited both by texture and attitude to the production of ordinary farm crops. Similar soils in ~~ 164 THE SOILS OF PRINCE GEORGES COUNTY other regions have proved valuable for the production of grapes, but reforestation is recommended for the majority of the areas found in Prince George’s County. THE LEONARDTOWN LOAM. The Leonardtown loam comprises a total area of about 70 square miles. It les entirely within the upland portion of the county, occu- pying the highest levels in the southern part of the county and cover- ing the gentle slopes along the border of the Piedmont Plateau. In the southern part of the county the surface of this soil type is flat or only gently rolling, while in the northern part it occurs somewhat less typically developed as a rolling or sloping surface. In all cases this soil type is bordered by areas of stony or gravelly soil. In other por- tions of the Coastal Plain this soil was originally occupied by exten- sive forests of white oak. When this timber is removed the areas occupied by the Leonardtown loam usually grow up to piteh pine unless cultivated. A considerable portion of this soil type in the southern part of Prince George’s County is still covered by white- oak forest, but in the northern part of the county it is almost entirely under cultivation. The soil itself consists of a yellow silty loam having an average depth of about 10 inches. It is underlain by a heavier yellow loam, which usually grades into a mottled loam at a depth of from 28 to 32 inches. At this depth the subsoil becomes brittle and crumbly, and a close examination shows that it consists of thin layers or lenses of clayey loam, which are separated from one another by thin seams or pockets of sand. Where the entire thickness of the soil formation does not exceed 5 or 6 feet the subsoil may also contain some fine gravel. Along the borders of this soil type the sand and gravel become more prominent as the soil becomes thinner, and the Leonard- town loam grades off into more stony or gravelly types. The entire area of the Leonardtown loam is underlain at varying depths by a bed of coarse gravel mingled with sand, which reaches the surface along the margins of stream valleys. This gravel and sand give rise to another type of soil, elsewhere described, and also play an impor- tant part in the natural underdrainage of the Leonardtown loam. MARYLAND GEOLOGICAL SURVEY 165 The mechanical analyses of this soil are shown in the accompany- ing table. The Leonardtown loam constitutes one of the heaviest types of soil cultivated in Prince George’s County. It is silty rather than clayey MECHANICAL ANALYSES OF LEONARDTOWN LOAM. 1| | 1D | PA s | | a a Ty 2 S S 3) a | g : So SI leer Ss) } sg i=) lo =] ° aa 19 eS 4 S es Nee ellie £ =) S 19 ro) a9 lag| & | 10 : S | ag ® Q } © ° le} | x ° | wa | om ° a is) Ss Bs) 2 , | as iar ov & 4 ~-giog | £8 = No. Locality. | Description. 12 S$ cS) : Ls) ) 3 ° 10 i | pa sites | € ae | .4 12 re 38 | as =I | wm a BE¢Clan s a € 2% 19 2 | co Ae i - | \ & oO =) | eee 2s si Pm 8 Beas a | ol a L q = ° eee |e | Ble le |e | a le a Ao] ete al a > =| bal — Gs) ° a Sec ll) KS) S ot ica =] =I in ie) o i) = ca - nm o a | : a = we = i 5 P.ct.|P.ct.|P.ct.| P. ct.| P. ct.| P. ct.| P. ct.| P. ct.| P. ct. 5467\24 miles NW.) Yellow silty loam, 0.01/2.78/0.96 10.92 9.08 5.86] 3.0451 .0016.69 of Muirkirk. 0 to 11 inches. | 5471|\Fort Foote....(Loam, 0 to 12 013.30 .00| Tr. | 1.32] 3.58)12.86)61.44/17.47 inches. | | | 54651 mile S. of Yellow loam, 0 to 0112.76) .00| Tr. | 4.16)12.70)15.28/43.36/21.35 Bryant’s | 7 inches. | | Point. | 54691 mile SE. of Yellow silty loam, .01 Oxon. 0 to 9 inches. | | bo 21.93 8.30, .00 1.04 1.18) 4.42) 4.56 61.7. 9.30) 5.9610.4240.4219.99 | 5468Subsoil of 5467, Heavy mottled, .01)2.98) Tr. 11.58 | | loam, 11 to 36) | | | | _ inches. | | | | 3.16/11 .98/41.5826.19 ~J ad ran es 5466Subsoil of 5465 Mottled loam, 7) .012 50) .00 Tr. | | to 24 inches. | | | | | | | | 5472Subsoil of 5471 Heavy loam, 12 .01/3.22} .00 pa 1.04 3.46 4. 7856.38 28.: | | | | to 86 inches, | 5470Subsoil of 5469 Mottled loam, 9) - » 12.06 00! Tr. | 1.58 4.64) 6.1653.9830.00 | | to 36 inches. | | | | | | in its texture, while the subsoil, on account of its composition and peculiar lenticular structure, offers a resistance to the circulation of water comparable to that of a heavy clay soil. This type of soil is capable of retaining a considerable supply of moisture during the entire growing season. It is, therefore, adapted to the production of grass, wheat, and corn where general farming is practiced, and to cabbage, cucumbers, and late strawberries in the trucking areas. Oo ~I 166 THE SOILS OF PRINCE GEORGE'S COUNTY This soil is only producing to its full capacity in the northern part of the county, where, through the use of green manures and lime, from 15 to 18 bushels of wheat per acre are frequently raised upon it. Elsewhere this soil type is generally lacking in organic matter. The Leonardtown loam should furnish an excellent soil upon which to introduce stock raising and dairying at points where market gar- dening can not be undertaken. THE LEONARDTOWN GRAVELLY LOAM. The Leonardtown gravelly loam occupies an area of about 6 square miles, occurring chiefly along the Montgomery County line. The surface is usually gently sloping and well drained, and this soil type is cultivated over the greater part of its area. The original plant growth on the Leonardtown gravelly loam has been quite generally removed, but the areas now in forest show a second growth of oak and pine in about equal quantities. This soil is farmed to corn, wheat, and grass. It is more typically a corn soil than a wheat or grass soil, though these crops are produced to a fair advantage in the regular rotation. The soil consists of a gravelly loam, containing from 15 to 30 per cent of fine and medium gravel mingled with some sand and larger amounts of fine material. The soil usually extends to a depth of 9 inches, and is underlain by a more compact yellow loam, which also contains considerable amounts of sand and gravel. At a depth of about 30 inches the subsoil is underlain by a bed of gravel and sand usually several feet in thickness. The soil thus constituted forms an intermediate grade between the heavy, grain-producing soils and the light tobacco and truck soils. It is thus adapted to a variety of crops. At present it is used for gen- eral farming. In addition to the corn, wheat, and grass now raised, the Leonardtown gravelly loam is capable of producing good crops of tomatoes, peas, sugar corn, and similar crops in demand for canning purposes. It requires careful farming and a more general use of stable and green manure to secure the best results from this type of soil. MARYLAND GEOLOGICAL SURVEY aM THE SASSAFRAS LOAM. The Sassafras loam covers an area of about 14 square miles. It is found in flat-topped terraces along the Potomae and Patuxent rivers and their major tributaries. It is distinctly a terrace formation, occurring here and elsewhere in Maryland as one of the stages of the Columbia group of Pleistocene age. It is essentially flat-topped or gently sloping, and the different areas are often widely separated from one another by areas of soil derived from underlying and older geological formations. The Sassafras loam terraces are underlain at a depth of from 4 to 5 feet by a considerable layer of medium-sized gravel, which generally reaches the surface along their frontal slopes in the shape of Susquehanna gravel. The Sassafras loam is occupied by areas of cleared and well-culti- vated fields, suited to general farming and the raising of wheat, corn, and grass in greater quantities than the general average of the county. This soil is found in several areas within the Coastal Plain of Maryland, and it has been proved to be of great agricultural value in all these regions. Besides the common crops already mentioned peaches, pears, asparagus, late melons, late strawberries, tomatoes, and cucumbers are adapted to this soil. The soil itself consists of a brown or deep-yellow loam, having an average depth of about 9 inches. It is uniformly underlain by a heavy yellow loam subsoil from 3 to 10 feet thick, which in turn rests upon an underlying gravel bed. The soil is capable of maintaining a good supply of moisture, and unless exposed to exceptional conditions of rain wash it is easily maintained in a good condition of produc- tivity. It forms one of the most desirable types of soils for general farming operations, but does not produce tobacco or early truck erops to advantage. The accompanying analyses show the texture of this soil to differ little from the Leonardtown loam, but in the field they appear quite different: THE SASSAFRAS SANDY LOAM. The Sassafras sandy loam is developed over considerable areas along the second bottoms of the main river courses at an elevation of 168 THE SOILS OF PRINCE GEORGE'S COUNTY from 60 to 90 feet above tide. The greater part of the area of this soil type found in Prince George’s County occurs in such a position, but several small areas occur in the low uplands of the northern central part of the county at an elevation of about 180 feet. In both eases the surface of the formation is nearly level and so situated as MECHANICAL ANALYSES OF SASSAFRAS LOAM. | —_ ‘ 7 Ss | . | a3 | 2 |) liom Rees g | = | | oO = =| . i=) | Me Ile So | = | ge eS co 1 = | i So prone E s = S 199 Bis ee \iati || ie S S | eo Pes = ° = 12 | og Ses | Boles] a = Se Se ee ° ola Tie script a eal f- a -g |/og|a g No. Locality. Description. Z = ° s S = Ee ° ioe | ag| ~ | 3 | Be) 28 | ao) Oe i aee| a os Z = | a2 » | > ge | me 2 el Sor pom lies = > | = = a = & | s | a | 5 5 Et a) |e ee 2 o st £ oI = Se || a) = i= > N a) | | | l |Prct.|P ct.|Pet.| Pict.P. ct: (b> Ct. | bach. etellancie 5491% mile S. ofSilty loam, 0 to 120.012.48 Tr. 3.08 3.64 9.7621.5050.40) 8.33 Queen Anne.) inches. | | | : ihe Piscataway. | 8 inches. | | | | | | | | | 54953 miles S. of Brown loam, 0 to .012.920.52 1.18 1.6812.66 7.94/61.88/10.91 549324 miles N. of Yellow loam, 0 to, .013.44 .00 1.36 2.74 8.46 6.38165.12111.53 | Bowie. | 12 inches. | | | | | leper | | | 5494 Subsoil of 5493. Heavy yellow loam, .012.74 .00 1.46 3.8412.36 9.7852.0817.97 | 12 to36 inches. | | | | 5496 Subsoil of 5495. Yellow loam, 8 to) .013.16 .3 .00| .64) 8.10)14.56)49. 72/21 .83 36 inches. | | | | 5492 Subsoil of 5491. Heavy yellowloam, .014.06 .00 3.16 2.70 4.62 7.8850.9826.33 | 12 to 36 inches. | | | | to be well drained and in good condition for agricultural purposes. Almost the entire area of the Sassafras sandy loam is under cultiva- tion to general farm crops. Corn, wheat, and grass—particularly clover—produce well upon this soil. Good crops of Irish potatoes and medium. crops of tobacco can be raised upon it. This soil type owes its origin to the deposition of sedimentary materials in late Pleistocene time. The soil itself consists of a brown sandy loam of medium to fine-grained texture. It is easy to cultivate, and responds well to careful treatment. It has an average depth of about 10 inches. The soil proper is underlain by a slightly MARYLAND GEOLOGICAL SURVEY 169 sandy or rather heavy yellow loam, usually more than 5 feet, in depth. While not so retentive of moisture as heavier types of soil, the Sassa- fras sandy loam is easily cultivated and its manipulation is perhaps better understood than that of the heavier soils. It is capable of producing a wider range of crops than it now supports. Green peas, sugar corn, and peaches are cultivated with success upon this soil in MECHANICAL ANALYSES OF SASSAFRAS SANDY LOAM. ae |e Bost tee mc ol elbs | oar ° t= < =| 1S oq |o . a S = aS ! Ta = = Yen] ° ° | 3 A | a Ore =| e ~ ~ = le) o | no Bu =I — Ls =) Gch | ° i 19 -3 } is | EN eS se ee bs) oS + | | aaa BE 2 en real oremli sls g No. | Locality. Description. Sa |e | 3g a Ea 5 D v6 S| 19 8 B 2 =| g a FI % | = or Ney || = ooh) 25) = aR ae S S Foetal] Zz = | 2 = EES| & = Bh dl te ¢ = as | oO = cal fo) o = o Sy) ee n J oS oD = > n 12) | P.ct.|P.ct.|P.ct.) P. ct.| P. ct.| P.ct.| P.ct.| P. ct.| P. ct. a = 4 P SA, aya wae y tev Peli ne 549923 miles NE. of Brown sandy loam,, 0.23.56/4.3813.02, 9.96|11.10| 6.9624.76/17.08 Hyattsville. 0 to 8 inches. | | | | | | | | | | 5497\1 mile SW. ofFine sandy loam,| .13.10)....|.....| 2.76|14.30/13. 42/43. 90124. 27 Collington. 0 to 9 inches. | | 2a fal meee ae Pal meaaistecal | Pe tealos wanlrawre 5500Subsoil of 5499. Micaceous yellow .23.84/6.7012.98 9.56) 9.42) 6.1627.7223.38 loam, 8 to 30 | | | | inches. | | 5498 Subsoil of 5497. Heavy yellow loam, .14.32)... ..... | 1.60|13.66| 4.88/48. 74126.61 9 to 36 inches. | | other localities. The texture of its soil and subsoil is exhibited by the accompanying analyses. THE NORFOLK LOAM, The Norfolk loam occupies about 15 square miles, chiefly in the “Forest of Prince George.” It occurs upon the uplands along the western and main branches of the Patuxtent River. The surface of the soil is rolling or hilly. It rarely descends below an altitude of 100 feet, and only in a few cases rises above 160 feet. Almost the entire area of the Norfolk loam has been under cultiva- tion since the early settlement of the county. The original forest was long ago removed and little second growth has been allowed to spring up. The fact that this part of the county is referred to as the “Forest of Prince George” would indicate that it was originally heavily timbered. 170 THE SOILS OF PRINCE GEORGI’S COUNTY The Norfolk loam consists of a very fine sandy loam soil, having a depth of from 12 to 20 inches. The subsoil consists of a reddish, sticky loam, commonly considered a clay throughout the region. This is underlain in turn by a fine, mealy gray sand at a depth that varies from 32 inches to 5 or 6 feet from the surface. The rolling character of the area occupied by this soil type gives rise to considerable variation in the texture of soil within single fields. Upon level or slightly inclined hilltops the sandy soil attains its greatest thickness and the gray sand, which constitutes the deepest subsoil, rarely reaches within 40 inches of the surface. Where the country is more rolling the surface sandy loam is thinner, and on the steeper slopes the sticky subsoil is barely covered by a thin layer of sandy loam. Frequently the gray sand reaches the surface lower down the slope and becomes stained to a light yellow color upon exposure to the atmosphere. The small streams which have their headwaters in this area are con- tinually transporting small amounts of the sand and sandy loam down their courses. This material, together with the outcroppings of gray and yellow sand along the hill slopes, has been mapped as a separate soil type. The Norfolk loam constitutes one of the soil types best adapted to the production of the Maryland pipe-smoking tobacco. For two hundred years this tobacco has been exported from southern Maryland, and the Norfolk loam, in Prince George’s County and adjoining areas, has produced the best grades of this tobacco from the beginning to the present time. From 750 to 900 pounds of tobacco are produced to the acre. Under weather conditions favorable to the maturing and curing of the crop a bright “colory” leaf is produced, which is noted in the foreign market for its free-burning qualities. The tobacco crop matures in about eighty or ninety days from the time it is transplanted into the field. It is eut, removed to the barn, and cured by natural processes without the intervention of artificial heat. The value of the crop is therefore dependent upon the weather conditions not only during its growth, but also throughout the long process of curing and preparation for market. A more uniform erade of tobacco has been produced by a few growers through the use of open fires in the tobacco barns. A few attempts have also been made at flue curing, but no definite results have yet been reached. MARYLAND GEOLOGICAL SURVEY ILL Corn, wheat, and grass are also produced upon the Norfolk loam. Wheat yields from 7 to 15 bushels, corn from 20 to 35 bushels, and hay from three-fourths of a ton to 11% tons per acre. Some difficulty has been experienced in recent years in the production of clover. Cattle and sheep raising are carried on to some extent, but the un- certainty of the grass crop and the lack of practical experience in dairying have largely prevented the introduction of these desirable MECHANICAL ANALYSES OF NORFOLK LOAM. : | i a hee fae eis |g |2 | @|s oa | 8 F et fe’ = E |S eS eee eee ole eS. PS ils “aS jag! & Nei | : S| | a) 2 ° : 19 -¢ Ah es | | g bo 4 a OF i 5 iS 2 Silene cality | Descripti a SFl og Te ee Be hese leas Slee No. | Locality. escription. Sees! & 3 Eg =a eis Ss | 25 | mw mi Eel an = We 2 lea oe oth 25) 2 See Sie eallen Sesja | z =| eee =e li Gl i) te yy |} eS) | > ee i [aes = co} oO | x a = | ¢g +S x | ° a es ° = road o = n |O ei) ts) = iS - n | 2) pee et Ee J ———————EEEe a a P.ct. P.ct. P.ct.| P. ct.) P. ct.) P.ct.| P.ct.| P.ct. P. ct. 54812 miles NE. of Fine sandy loam,0.01 B-10)-- 0.44 0.4616.6025.5045.08 7.35 Leeland. _ 0 to 10 inches. | | | | 54832 miles N. ofFine sandy loam,| .012.08)....)..... 1.1830. 74/41 .82)13.22/10.41 Upper Marl- 0 to 8 inches. | | | boro. | | 5484 Subsoil of 5483./Fine to medium] .01/1.84)..../ ....] 1.12)387.64)40.28/12.48) 6.17 | sand, 8 to 36 | | | | | inches. | | | | | | a yeas S 482 Subsoil of 5481. lHeav y yellow loam,| .01/2.46)....|....- Tr. |12.18|28.94)34. 7220.25 | 10 to 32 inches. | industries. The Norfolk loam, though exhibiting some differences in character over small areas, presents a constant type of soil adapted to the production of Maryland tobacco, and gives fair returns in general farming operations. The soil and subsoil in this area are of a somewhat finer-grained texture than elsewhere in southern Maryland. THE SUSQUEHANNA CLAY. The Susquehanna clay covers more than 55 square miles of ter- ritory, lying along the main railroad lines connecting Washington and Baltimore. The greater part of the area remains uncultivated, 172 THE SOILS OF PRINCE GEORGES COUNTY and is widely known on account of the vivid red and purple coloring of the subsoil. The peculiar properties of this subsoil have formed the subject of extended chemical and physical research. This soil type occupies steep valley walls, irregular hills, and stream bottoms alike. It is usually deeply gullied by small stream courses, and frequently bears no vegetation whatever. Where the natural processes of weath- ering have produced a shallow soil, a sparse and scattering growth of oak and pine is found. The scanty soil covering in this area consists of 4 to 5 inches of a yellow clay loam. It is underlain by a stiff, plastic mottled clay, which is red, gray, or purple in color. This clay has been used exten- sively for the manufacture of brick, sewer pipe, and drain tile. The very properties which adapt it for this purpose make it unsuitable for cultivation. The numerous mechanical analyses that have been made of this soil show that it differs but slightly in texture from the rich and fertile clays found in the limestone areas.’ It seems probable that the structure of this soil plays a more impor- tant part in the determination of its character than is the case with most soils. The fine particles which make up the greater percent- age seem to be so evenly distributed that whatever moisture pene- trates it is distributed evenly through a great number of very minute pores. The circulation of soil moisture is thus impeded, and while a large supply of water is maintained, it is so immovably held as to be of little use to growing crops. The Susquehanna clay, where it is exposed at the surface with no covering of any other material, produces very little vegetation of any value. The scattered timber found upon this type is cut for railroad ties or for the production of charcoal. The few cultivated areas found upon the Susquehanna clay are not successfully farmed. In every known case where crops are produced to advantage within the Susquehanna area the immediate soil is formed by Pleistocene or other extraneous material that covers the clay to a depth of 8 or 10 inches. Even when so covered the successful production of crops depends upon careful and skillful farm management. Certain por- 'Texture of Some Important Soil Formations, Bulletin 5, Division of Soils U. S. Department of Agriculture, 1896. (oN) MARYLAND GEOLOGICAL SURVEY 1 tions of the area fall within another soil type (Susquehanna clay loam), and these portions are distinguished from the Susquehanna clay by marked features of origin and soil texture. That some remedy for the unproductive conditions of the Susque- hanna clay can be devised is firmly believed. The present structure of the soil and subsoil must be changed by the application of sub- stances which will tend to flocculate the soil particles. In this man- ner the circulation of the soil moisture and the soil atmosphere should be facilitated and the stores of plant food, which have been shown by chemical analysis to exist in this soil, should be made available. Lime is one of the substances that produces such a floc- culating effect upon puddled soils, and it not only improves the soil texture, but also aids in the chemical reactions necessary to make available the reserve supplies of plant food. It also acts directly as a plant food itself. Lime has already been used upon a soil formed by a surface layer of about 8 inches of Pleistocene loam over- lying the Susquehanna clay subsoil. In this case good clover and fair grain crops have been produced. While the conditions differ from those pertaining to the most marked type of Susquehanna clay, the beneficial results would seem to indicate that the experiment of lim- ing should be thoroughly tried upon that type. The transformation of the semibarren areas of Susquehanna clay to a productive soil is a result greatly to be desired, and thorough experimentation along scientific lines may yet accomplish it. The accompanying table shows the texture of typical samples of Susquehanna clay. THE SUSQUEHANNA CLAY LOAM. Throughout the region occupied by the clays of the Potomac group there are found areas which, owing to the presence of lenses of sand or to the partial covering of Pleistocene material, do not fall within the limits of the Susquehanna clay. These areas, approximat- ing an area of 26 square miles in Prince George’s County, are irreg- wlarly scattered through the western part of the county. They are found on hilltops, on slopes, and in the valleys alike, and are fre- quently cleared, though considerable areas still support a forest growth of oak and pine. 174+ THE SOILS OF PRINCE GEORGES COUNTY The surface covering of the Susquehanna clay loam consists of about 10 inches of sand or sandy loam, though its depth may be some- what less, but the distinguishing feature of this soil type is the heavy mottled clay subsoil, which is identical with the Susquehanna clay. The surface covering of sandy loam, however, furnishes an easily tilled seed bed which is of sufficient depth to germinate seeds and nourish the young plants. The heavy clay subsoil, covered by this loose-textured soil, serves as a reservoir for maintaining a good mois: MECHANICAL ANALYSES OF SUSQUEHANNA CLAY. [Fine earth. ] =| fs sc | 0 ° 5 Iss | 8 iam Pace Pian || el |S EI c BS | oy E S | \ Tax cs = re ° Ss | . 4 | least Ere Se S Sa tlie lg2 |eg| 5 ete ake a4 | S | eee oes |S | - |O6 |S 8 ees [ores No. | Locality. Description. B 2s) | © 3 gH|°8 |g o |G 0. | ocality eseriptior 44 |< & = EE i: ne = 2 8 a lagi a EI i E ted fy |) SS gel Sea ee ele 5 e SS 25s 5 Bs £ | = o | b | be eRe 8 |e Ga eee oe elon eas. lh eos na | P.ct./P.ct.P.ct. P: ct. P. et.|P: ct.| P. ct./ P. et.| Pacts | xno! a ‘ab Va ° = ") Ke Fae = 9«¢ « 5903% mile N. of/Yellow silty loam,0.011.700.00) 0.00 5.5624.7814.1043.28) 9.93 . . | Ardwick. 0 to 6 inches. | | 5001/1 mile N, ofjClay, gravel, and | Agricultural] iron crust forest -01/4. 709.38/12..90 5.36 8.56) 7.4216.1655.71 / | College. land, 0to4 inches. | | 5504/Subsoil of 5503.|Mottled clay, 6 to | 36 inches. -013.260.00) 2.20) 1.98) 8.70) 5.4242.7836.55 Mottled clay, 4 to | | | | 5502’Subsoil of 5501.' 30 inches. .01'4.90'1. 20! 2.62) 2.1611.6819.1621.12'36.55 ture supply, and its imperviousness aids in the retention of plant foods, which would be leached readily from the soil alone. As a result this modification of the Susquehanna clay, by the interven- tion of other materials to form the soil, gives rise to a type adapted to general farming, and especially to grain and grass crops. This type of soil requires very careful farming. Lime is used to good advantage, and with its use some excellent clover crops have been produced. The accompanying table gives the mechanical analyses of soils and subsoils of this type of soil: THE ELKTON CLAY. The Elkton clay occurs locally in several small areas adjacent to stream courses in the northern portion of the county. Its surface is low lying, usually flat, and rather poorly drained. MARYLAND GEOLOGICAL SURVEY ae The soil consists of a brown or gray silty loam having an average depth of about 9 inches. It grades down into a heavy yellow loam which is underlain at about 28 inches by a mottled yellow and gray clay loam. On account of its low-lying position this soil is apt to be wet and difficult to cultivate. For the same reason the circulation of the soil moisture and the soil atmosphere is impeded. In its natural state this soil is occupied by the sweet gum and wil- low oak. When cleared it affords good grazing, and is capable of pro- MECHANICAL ANALYSES OF SUSQUEHANNA CLAY LOAM. bist | g 10 = ° | ae ad se |g Be hard lke a et f |S ee} i) = = So Sal | = i=) ood} a a 1 } fo} 2 A a Sip5 = oS ~ ~ fan) 10 oO no ae = 5 = eGo | SAS eee 19 et oe Nite | ‘=| ta coal o i J Oo + So oe 4 s spe Seto og No. Locality. Description. ay |= i a || = 2 a | ® S | Fesoctien |) sures = 3 AG FS oie a 2 20S | Be s % = | 2° } 3s | — roe a | eg | Res Saas Bas] a S R 5 i} oc EE S| & Bea ee (ies Comes alas —_— = OS] = oS [= | ~ ~_ lotes fo) ra BH a) od = | @ fot oN) n ©) ido} o = eS = n | Oo —r | a 7 con See focal r P.ct./P.ct.|P.ct.| P. ct.| P.ct. Peer eset Pects|/Pacte | = cd | 20 Fe 550524 miles NW.\Yellow loam, 0 toj/0.013.52) Tr.| 2.10 3.62) 7.96/12.6857.14/12.29 of Piscata- 9 inches, | | | way. | | | le | React eran eee! = 9007/14 miles S. of/Brown loam, 0 to} .016.18)0.98) 2.80) 4.16 8.82) 3.9643.34/29.17 Agricultural 6 inches. | | | College. | | . ~n~ « eo! ¢ 26 > Ie € ae 5906 Subsoil of 5505. Mottled clay, 9 to .013.72....| Tr. | 2.62 5.06 5.9055. 2626.31 40 inches. ducing excellent crops of wheat and grass. The small areas of this soil occurring in Prince George’s County can be made to produce from 25 to 35 bushels of wheat or 2 tons of hay per acre by proper underdrainage and intelligent cultivation. The texture of representative samples is shown in the accom- panying table. THE CECIL MICA LOAM. The Cecil mica loam is a residual soil, occupying an area less than 1 square mile in extent in the extreme northern portion of Prince George’s County and considerable areas in the District of Columbia. It is found along the steeper stream courses where overlying sedi- 176 THE SOILS OF PRINCE GEORGES COUNTY mentary materials have been removed by erosion. The surface of this soil type is rolling or deeply sloping, and it usually descends to rocky, uncultivated areas along the streams. This soil has been derived from underlying crystalline rocks through the mechanical and chemical processes of weathering. The circulation of atmos- pherie water charged with various chemicals has broken down the minerals of which the rock was composed. The action of frost and MECHANICAL ANALYSES OF ELKTON CLAY. | | tt ' = 1D - ° : rc a) = = nN : ~ | ‘=I i) vo = | 5 o H lag | 8 a Se | epee iet=l ibe Sa ae Bs 19> ° 2} : | = = ibe = . a) + So 10 ° i 3) ais5 = i=) | So laa |ee| & ° 19 10 re S Nees Roe |e SR Sen |: a eepee Il a ies co t& — -< occ a : No. | Locality. Description. ie eo) © = ° FSI eS a oS || SS a Ls} S S ‘ Re ur thie oe ee ete Sa ai ors a | oe No. Locality. Description. KS) 25 S co re a S Ne) = | or < | cuts Ue} Oo g Sal Se s or] 2 —) Me all IS] oS a = OS Ne) 2 oe oa 3 a Sea XS ooh 2a] a E a | Sil S83] a = cA 5 | z | See S a ray cs] ® b = be a= Am] oO oe] = i=} nl n= os | ie zm il 5 o = ® =| s | nN S) ids} 6) = ica > n 1S) | cs a aie cn q | ej ; | P.ct.|P.ct.|P.ct.| P. ct. | P.ct.| P.ct.| P. ct.| P. ct.| P. ct. 54492 miles north-Micaceous brown0.01/4.24'4.5415.0412.36 26.5210. 28)17.60,10.67 westof Laurel loam, 0 to 12 | | | | inches. | | | | | 5450\Subsoil of 5449. Micaceous reddish (014.504.7211. 2410.56 25.08 7.24119.02)18.43 loam, 12 to 40 | | | | inches. | | | | THE MEADOW. All soils in this area are classed as Meadow whose chief charac- teristics are a level, low-lying position and a poorly drained or semi- marshy condition. Nearly all of the areas thus mapped are at times subject to overflow by flood waters, and over most of them an inter- mittent deposition of gravel, sand, and silt takes place at such times. The meadows are largely forested by water birch, sycamore, sweet eum, and willow oak, interspersed with a rank vegetation of running vines and coarse grass. They are usually uncultivated, and are used only to furnish grazing during the drier portions of the year. alg THE SOILS OF PRINCE GEORGE'S COUNTY oa) Over these areas the process of soil formation is still in progress, and the meadow areas constitute incomplete stream terraces which are not yet adapted to cultivation. Some portions of the meadow area mapped in Prince George’s County could be transformed into agricultural lands by underdrainage or by inexpensive diking. Filled Material.—This represents that part of the city of Wash- ington where the surface has been elevated by bringing in material from other parts. On the islands bordering the Potomac the material has been pumped from the river and allowed to settle in still water. This is either a rich dark loam or sandy loam. It is almost entirely above flood level and is capable of producing large crops. Some of the trial gardens of the Department of Agriculture are located on this material. Over Capitol Hill, in the northwest section of the city, and through Mt. Pleasant and the Soldiers’ Home regions large areas have been graded down from 2 to 20 feet, but of this no account has been taken and the original types are shown on the map. Tur AGRICULTURAL CONDITIONS. At the present time the land holdings of Prince George’s County vary in size from 100 or 200 acres up to 1,000 acres or more in a single tract. The larger farms are worked under a tenant system, the tenants making payment either in cash or in farm products, under varying conditions of contract. Near the boundary of the District of Columbia many of the larger farms have been subdivided into small parcels and sold to persons desirous of engaging in market gardening. Upon these smaller tracts are produced radishes, let- tuce, tomatoes, cucumbers, melons, green peas, sugar corn, and berries, which are transported to Washington by team and there either sold from market stalls or peddled from house to house. Upon these market-garden farms an intensive system of cultivation has been practiced in order to produce a steady supply of the various crops in season. The labor upon these small tracts is largely per- formed by the owner, the members of his family, and a few hired hands. Large amounts of lime, gas lime, and stable manure are MARYLAND GEOLOGICAL SURVEY alge) obtained from the city to maintain the fertility of the market-gar- den farms. The trucking industry, which is carried on to some extent in north- ern Prince George’s County, differs from market gardening in that larger tracts are cultivated under a single management and larger areas of single crops are produced, to be sold on commission in the various markets. The chief trucking crops of the county are green peas, strawberries, and sugar corn. To these should be added early Irish potatoes and sweet potatoes, which are also produced in con- nection with the general farming crops. The trucking and market-gardening areas are confined to the northern and northwestern portions of the county. Tobacco, while not confined to any particular locality, is most successfully produced ? which extends in the area known as the “Forest of Prince George,’ from Bowie southward along the Patuxent to the extreme limits of the county. Of the general farm crops corn ranks next to tobacco in importance. Wheat is the only other grain produced extensively, though considerable areas of rye are sown, largely for the pasturage furnished, the grain entering as an incidental profit. The raising of cattle and sheep is being reintroduced into the county, although attended by some practical difficulties. Upon those farms where tobacco is raised lime is little used, since its application injures the burning quality of the leaf. Commercial fertilizers, however, have been used in large quantities for many years to increase the production of tobacco and the grain crops. They have been considered a complete fertilizer in many cases, and too little attention has been paid to the restoration of organic matter to the soil. Recently leguminous crops in the form of cowpeas and crimson clover have been introduced and the system of agriculture improved through this means. The production of good forage crops can only be resumed by a more generous use of lime and the legu- minous green manures. The cowpea seems better adapted to this end than any other leguminous crop. The restoration of the soils to conditions favoring grazing must necessarily be slow. Many of the farmers of the region recognize the desirability of raising more stock 1s0 TEES SOLS) Oh Palin Gis GEORGE'S COUNTY and are seeking to enlarge their facilities by raising redtop and other erasses. Among the soils of the county the Cecil mica loam is notable as the only residual soil. It occurs in many other areas along the Atlantic coast, and is usually cultivated to corn, wheat, grass, tomatoes, and orchard fruits. Under favorable conditions of season it is capable of producing 15 to 25 bushels of wheat, 45 to 60 bushels of corn, and 1 or 2 tons of hay per acre. It is not a heavy soil and therefore, while quickly responsive to applications of commercial fertilizers or stable manure, it requires frequent applications of fer- tilizer and careful farming to maintain the yields quoted. The Elkton clay is a strong productive soil when properly drained, and with careful management is capable of producing 30 bushels of wheat or 2 tons of hay per acre. Liming and underdrain- age are the chief requirements of this soil type. The Leonardtown gravelly loam is better adapted to the production of peaches, pears, and other orchard fruits than to general farming. Its texture, location, and drainage fit it for the fruits named. The yield of wheat ranges from 15 to 18 bushels per acre; of corn, from 30 to 35 bushels. The Sassafras sandy loam is one of the most valuable of Coastal Plain soils. In addition to its good texture it contains large stores of plant food, is well drained and possesses a level, easily tilled surface and usually an advantageous location with regard to transportation facilities. Its full capabilities as a general crop soil have not been reached in Prince George’s County. With proper fertilization, including the use of stable manure and of green crops plowed under, the Sassafras sandy loam should produce 25 bushels of wheat, 50 to 60 bushels of corn, and 2 tons of hay per acre. It is also well adapted to the production of tomatoes, green peas, sugar corn, broom corn, cabbages, and cucumbers. It is not a typical early truck soil, but is capable of yielding good results when devoted to market gar- dening. The Sassafras loam is found in many localities in the Atlantic Coastal Plain. It is uniformly a medium to heavy loam, capable of a high development as a general farming soil. In southwestern New MARYLAND GEOLOGICAL SURVEY 181 Jersey large areas of this soil produce 30 to 35 bushels of wheat, 45 to 60 bushels of corn, 8 to 9 tons of tomatoes, and 2 tons of hay per acre. It is the soil most preferred for stock raising and dairying, and possesses an average value of $50 to $65 per acre. On the Kast- ern Shore of Maryland extensive tracts of Sassafras loam are devoted to peach and pear orchards, while tomatoes, sugar corn, and green peas are raised for canning. The type there is valued at $35 to $60 per acre. In southern Maryland, including Prince George’s County, a much smaller range of crops is cultivated on this type, though the climatic, soil, and market conditions are nearly identical in the three regions. The type is valued at only $12 to $25 per acre on the aver- age in the county. It is thus seen that the opportunities for improve- ment in agricultural methods, for the introduction of new crops, for the development of new industries, and for the profitable investment of capital are many and great. The Leonardtown loam constitutes the nearest approach among Maryland Coastal Plain soils to the heavy wheat and grass producing soils of limestone regions. In spite of its level surface and _ its advantages of drainage this type has been allowed to grow up to pine and oak forest to a considerable extent since the civil war. It is not adapted to the production of tobacco, and its capabilities in other directions have remained unknown or unappreciated. This soil type needs extensive applications of lime and green manures to make it highly productive. It should produce good crops of wheat, corn, and grass, and form the basis of dairying or stock-raising activities. It is the most extensive of the soil types in the county, and it can be bought for $1.50 to $5 per acre in the unimproved state or for $5 to $10 per acre improved, within a few miles of the District of Colum- bia line. Experiments in other areas have shown that proper man- agement will make this soil produce from 15 to 20 bushels of wheat, from 35 to 50 bushels of corn, and from 1 ton to 11% tons of hay per acre. ‘The only means employed to secure these yields have been the application of lime and stable manure. The Norfolk sand is a typical Atlantic Coast truck soil. It is a mealy, porous, warm sand, well drained and easily cultivated. In regions where trucking forms an important part of agriculture this 182 THE SOILS OF PRINCE GEORGES COUNTY soil is sought out as best adapted to the production of watermelons, canteloupes, sweet potatoes, early Irish potatoes, strawberries, early tomatoes, early peas, peppers, eggplant, rhubarb, and even for cab- bage and cauliflower, though the latter crops produce better yields on a heavier soil. The Norfolk sand in Prince George’s County is well situated with regard to the markets of Baltimore, Washington, Pitts- burg, and Philadelphia. Its climatic surroundings are favorable and the prices of land low. It should serve as the basis for a strong development of the truck industry in that county. In texture the Westphalia sand is considerably finer grained than the Norfolk sand. On the other hand, it is not so distinctly loamy as the Sassafras sandy loam. It furnishes a type not so well adapted to the production of the early truck crops as to the raising of Irish pota- toes, peaches, small fruits, and tomatoes. It is too sandy and porous to produce good yields of grain or grass, even when well fertilized. The more level, sheltered portions of this type in Prince George’s County produce a fair yield of tobacco, while the steeper slopes are almost barren of any crop. The Westphalia sand is deficient in organic matter, and its texture and fertility can be considerably im- proved by the use of green and stable manure. The Windsor sand is the loosest, most incoherent soil of the area. It does not retain sufficient moisture to mature the grain crops to advantage, but is well adapted to small fruits, such as raspberries and currants. Peach orchards located on this type are noted for their long life and for the size and beauty of the fruit produced. The Susquehanna gravel exists only in narrow bands and small isolated areas. It is totally unfitted for most agricultural purposes and should remain in forest wherever possible. Grapes are raised on soils of similar texture in other regions, and the possibility of their culture on Susquehanna gravel should be experimentally determined. The Norfolk loam has long occupied a commanding position in the production of the Maryland type of smoking tobacco. The hilltops throughout the “Forest of Prince George” are capped by this soil type, and the yield of tobacco and the prices commanded have been uniformly good in this region. In other areas of the type the same conditions hold. This type is commonly fertilized by the use of the MARYLAND GEOLOGICAL SURVEY 188 commercial products, though lately cowpeas have been employed in conjunction with the manufactured fertilizers. It is a fundamental principle with the tobacco growers that the application of lime on fields where the crop is to be raised injures the burning quality for which the tobacco is esteemed. In consequence, where tobacco is to form part of the crop rotation the other crops of the rotation suffer for lack of lime for the sake of the one year’s growth ot tobacco. The soils of this region all require lime for the production of grain and grass, and the present rotation, based on tobacco, does not permit the Norfolk loam to produce other crops to its best ability. The Collington sandy loam is a peculiar soil derived from the decomposition in place of a greensand stratum. The resulting soil is a medium sandy loam underlain by a sticky, heavy sandy loam. The physical texture of this soil gives a warm seed bed, producing quick germination, and a good subsoil reservoir to maintain a water supply during the period of growth, while its chemical composition insures a good supply of potash salts, one of the most expensive plant foods when purchased as a fertilizer. The complete commercial fertilizer is not required on this soil so much as an application of phosphate rock, coupled with the production of cowpeas to supply nitrogen. These should be plowed under, in order to furnish addi- tional organic matter. This soil type produces good crops of wheat, corn, tobacco, and grass, and is also adapted to Irish potatoes and fruit. In its sandier portions it raises good truck crops. The Susquehanna clay constitutes one of the most intractable soils of the region. It is a sticky, plastic mass, difficult to cultivate, liable to excessive baking in dry times, and comparatively unproductive over a greater part of its area. Little has so far been accomplished toward the solution of the agricultural problem it presents. The extensive use of lime corrects its textural faults to some extent, and good crops of wheat and clover have been produced under this treat- ment. The Susquehanna clay loam possesses a loose sandy or loamy soil capable of cultivation and of forming a natural mulch over the dense clay of the subsoil. As a consequence it forms a fair seed bed and yields medium crops of grain and grass. 154 THE SOILS OF PRINCE GEORGE'S COUNTY The great variety of soils found in the county, the moderate climate and general healthfulness of the greater part of the county, its accessibility by rail and by water, all favor a greater specializa- tion of agriculture and increased profits from the cultivation of the soil. The location of Prince George’s County is such that the further extension of the suburban residence section may be reasonably expected. Market gardening will also cause the further subdivision of the larger tracts of land, particularly those located near the District line. The area used in trucking operations is also increasing and should ultimately occupy the entire extent of the sandier types of soil. The canning industry should be introduced, for the climatic conditions and the great diversity of soil would permit of a con- tinual succession of canning crops during the usual growing season. de THE CLIMATE OF PRINCE GEORGE'S COUNTY By e WILLIAM H. ALEXANDER. INTRODUCTORY. The principal object for which the Maryland State Weather Ser- vice was organized is to study thoroughly the climatic features ot the different sections of Maryland, to ascertain as far as possible the effect of each of the controlling factors, and to publish the meteor- ological data available in sufficient detail to enable students to inves- tigate the numerous problems of climate as related to hygiene, agriculture, and the mechanical arts, the solution of which is impor- tant for the welfare of the people. Pursuant to this plan, a General Sketch of the Climate of Maryland, by Mr. F. J. Walz, was pub- lished in Volume I of the Maryland Weather Service Reports, and a full account of the Weather and Climate of Baltimore, by Dr. Oliver L. Fassig, appeared in Volume IT. Chapters have also been pub- lished on the climate of five counties in the State, namely Allegany, Calvert, Cecil, Garrett, and St. Mary’s, and it is intended ultimately to cover every county in the State. Collected into one volume, these county reports will form an invaluable summary of meteorological information for the student. THE FACTORS CONTROLLING CLIMATE.! The climate of any region depends primarily upon the following chief factors: Latitude; the physiographic features of the region, especially its position with reference to mountains or large bodies of water; to a 1The author has employed in his introductory paragraphs the general state- ments used by Mr. C. F. von Herrmann in earlier reports of the Survey. 186 THE CLIMATE OF PRINCE GEORGES COUNTY minor degree on its topography, the slope of the surface, whether valley or mountain top, the nature of the soil and soil covering, and lastly, on the position of the region with reference to the prevailing path of storms. | The sun’s power is greatest when the rays strike the earth’s surface vertically, and the highest temperatures might be expected to occur in regions where the sun is overhead at noon, which can take place only within the tropics. The inclination of the earth axis 231 degrees from the perpendicular to the plane of its orbit profoundly modifies this simple deduction by causing a variation in the length of the day as the pole is approached. During the summer of the northern hemisphere the length of the day increases rapidly from the equator toward the pole, and the increased duration of sunshine compensates largely for the greater inclination of the sun’s rays. Maryland, lying between the parallels of 38° and 40° north Latitude, at the time of the summer solstice, June 21, has a day of nearly 15 hours’ duration, and the soil and air are able to accumulate a large store of heat during the long summer day. The long winter nights which favor the loss of heat by outward radiation give a sharp con- trast to the different seasons which is quite absent in polar or tropical latitudes. The factors which control climate act together in so intricate a manner that it is difficult to ascertain precisely what effect latitude itself to the exclusion of other causes may have upon the climate of a region. The position of a country with reference to mountain chains or to large bodies of water has a profound effect on climate. Over any level plain, even in tropical regions, the temperature decreases in free air about 1° Fahrenheit for every 300 feet increase of elevation. Mountains thrust themselves up into this region of colder air and thus lower the temperature of their surroundings. Again, moun- tains have a strong influence on rainfall by facilitating the ascent of moist air, currents flowing up their slopes, and so causing con- densation and precipitation by dynamic cooling. On the other hand large masses of water have a conserving influence, lessening extremes of temperature, and their action is so powerful as to determine the difference between what is called continental and marine climates. =~] MARYLAND GEOLOGICAL SURVEY 18 The valleys in a mountain region have greater extremes of temper- ature than the mountain tops, being usually warmer during the day and in summer, and colder at night and during winter, because the cold air flows down the slopes and accumulates in the depressions. The effect of the nature of the soil and soil covering is also important. The mean temperature of the soil is always higher than that of the air above it. There are great differences, however, in the amount of heat which different soils return to the air. In rocks the temperature is higher at all depths and at all times of the year than in the overlying air, consequently rocky soils give up more heat to the air than other kinds. In sandy land the upper layers only are warmer than air, while moist lands or bogs are colder because much of their heat is lost in causing evaporation. A covering of vegetation lowers the temperature of the soil, and changes in temper- ature over grass and forests are less than over bare soils. Incidentally forests conserve the rainfall, returning it slowly to the streams and diminishing the evil effects of drought. The position of a place with reference to the prevailing path of storms determines the frequency of rainy days, the cloudiness, the winds, and all the variable phenomena called weather, which are non-periodic¢ in occurrence. THE PHYSIOGRAPHIC FEATURES OF PRINCE GEORGE'S COUNTY. In order to correctly interpret the climate of Prince George’s County it is essential to have some knowledge of its physiographic features, but as complete details will be found in other portions of this volume, it will only be necessary to give here a brief recapiiu- lation of the main facts. Geologists divide the region east of the Appalachian chain into two well-known physiographic provinces: the Piedmont Plateau, and Coastal Plain. In Maryland the Coastal Plain includes all that portion of the State lying east of a line extending from southwest to northeast through Washington, Baltimore, and Wilmington, Del., or about one-half the area of the State. The Coastal Plain is divided into two portions by Chesapeake Bay, the higher western division 188 THE CLIMATE OF PRINCE GEORGE'S COUNTY being known as Southern Maryland. It includes St. Mary’s, Ca!- vert, Charles, and Anne Arundel counties, and all but the extreme western margin of Prince George’s County. The characteristics of the Coastal Plain, important from a climatic standpoint, are its low, level lands, composed mostly of unconsoli- dated sands and clays, and the deep indentation of the region by Chesapeake Bay, its rivers and tributaries. The elevation of the land is considerably higher in the western peninsula than in eastern Maryland, frequently exceeding 100 feet even along its eastern mar- gin, and reaching 280 feet farther west near Washington. Elevation does not, however, enter as an important climatie factor in determining the weather of the county and hence marked climatic differences are not to be expected. The causes that determine the prevailing weather in this area are to be found in general rather than local conditions and depend very largely upon the geographical position of the county with reference to the paths usually followed by the great storm areas as they move across the country. As these matters have been fully elaborated in Volume I of the Maryland State Weather Service further discussion in this connection will not be necessary. MerrroroLoeicaL Dara AVAILABLE FOR PRINCE GrorGE’s County. The discussion of the climate of Prince George’s County and the District of Columbia is greatly facilitated by the fact that there are such a large number of stations from which reports have been secured. Furthermore, these records, notably those from Washing- ton, are especially valuable not only because they extend back over a longer period of time than the majority of available climatological records but also by reason of the fact that they were made by experts using the very best known instruments exposed in the most approved scientific manner. Practically all the meteorological observations made at the foi- lowing stations were made under the auspices of some organization or institution. It may be well to state briefly the more essential points in each system concerned as the instrumental equipment and hours of observation are uniform for each. MARYLAND GEOLOGICAL SURVEY 189 The observations made under the direction of the Surgeon-Gen- eral’s Office of the Army Medical Department are, as a rule, made at 7 a. m., 2 p. m. and 9 p. m., and include the reading of the barometer, the thermometer, hygrometer, raingage, force and direc- tion of the wind and the state of the weather. Fic. 2—Map showing stations from which meteorological data are discussed. The observations made under the direction of the Smithsonian Institution are also made at 7 a. m., 2 p. m. and 9 p. m., and include the same phenomena as the preceding observations except there are no readings of the barometer. 190 THE CLIMATE OF PRINCE GEORGES COUNTY The U. S. Weather Bureau observations at the regular stations are made at 8 a. m. and 8 p. m., 75th meridian time, and include the readings of the barometer, thermometers (exposed, maximum and minimum), raingage, velocity and direction of the wind and the state of the weather. At voluntary, or codperative stations, the Smithsonian system was continued until 1888 and then for a few years the observations were made at 8 a. m. and 8 p.m. Later the exposed thermometers were replaced by maximum and minimum thermometers which are read but once each day, usually late in the afternoon. In the Maryland State Weather Service each station is equipped with a maximum and minimum thermometer and a raingage which are read once each day, the observer also noting direction of wind and state of weather. In the tables which follow the monthly and the annual extremes are printed in heavy type instead of repeating them as a separate item. Letters appearing in the tables indicate the number of days missing from the original record for that month. Thus a, one day; b, two days, ete. TABLE I. METEOROLOGICAL STATIONS, PRINCE GEORGE'S County, Mp. . Latitude. | Longitude. | Elevation. phan 6% Station. | RGTTEL West. | (Feet.) Observers. a = = Bladensburg......) 38° 57’ 76° 58” 105 ~~ / Benj. O. Lowdnes. | Role | : William F. Wallis Jheltenham...... ) Bile gay 6: 514 230 et hears e Cheltenham ) 3 44 76°5 3 SRimbaverisern te be a thes acs | = Dr. C. M. Jones Yollege Park. ...) 38°55’ 6°57 «| 170 ee : oles eles ‘i Wg hae shared Prof. H. J. Patterson = i ‘Dr. Jno. W. Bayne For ae Bhi | o OF 150 (ee Oe EO. ga ay | (U.S. Post Surgeon) Fort; Washingtom:| 38°42/° 1) 77° 27° 9) 100 ~—|U. S. Post Surgeon. Waurel) Aces eres 39° 167 16° 52/7 150 iDr. T. M. Baldwin. Nottingham...... 389497 76° 437 25 Dr. Richard Brooke. A. P. Dalrymple. Upper Marlboro... — 38° 48” 169 45055) Ie J. Benson Perrie. oe : = EN Nags | U.S. Weather Bureau Washing } 3o204e oe SC 2 |U. ; i shington, D.C. 38° 54 Kg 3 | 11 and others. MARYLAND GEOLOGICAL SURVEY 191 The foregoing table shows the stations from which meteorological data are included in the present discussion. TEMPERATURE CONDITIONS. The average temperature conditions for Prince George's County are given in the following tables. The average for the year is about 54 degrees and the range in the monthly mean temperatures is about 42 degrees. January, as a rule, is the coldest and July the warmest month of the year. The extreme maximum temperature (the highest ever recorded at any station in the county) as shown in the following tables is 105 degrees, recorded at College Park in July, 1898, and the extreme minimum temper- ature is 18 degrees, recorded at Laurel in February, 1899, indicating an extreme range for the county of 125 degrees. It will be of interest to compare these temperatures with similar data for Garrett, the coldest county in Maryland: Annual Warmest Coldest County Mean Month Month CULT GUE Myers alec cls lene volelesisue eis 47.0° 68.0° in July 24.0° in February. Prince! (Georgers: eos wis sis cole 54.5° 76.8° in July 33.3° in January. Garrett County is much colder chiefly on account of its far greater elevation above sea level. The average date of the last killing frost in the Spring is April 7 for Washington, April 16 for Cheltenham, and April 20 for Laurel. The latest date recorded for a killing frost is May 11, 1906. The average date of the earliest killing frost in the Fall is October 22 for Washington, October 21 for Cheltenham, and October 18 for Laurel. The earliest dates recorded for a killing frost are October 2 for Washington, October 9 for Cheltenham, and October 1 for Laurel. PRECIPITATION. As Mr. Von Herrmann correctly points out, precipitation is an extremely variable element of climate, and very great differences may be found at stations not widely separated; no corrections can be 192 TIE CLIMATE OF PRINCE GEORGE'S COUNTY applied to short records of rainfall, the averages for the various stations in the county are given in the accompanying tables. Prince George’s County receives about 42 inches of rain per annum. While this amount is slightly less than that for most other counties farther north, it is not the lowest value in Maryland, which appears to obtain in Allegany County, where the annual rainfall is approximately 84 inches per annum. As in all other counties of Maryland the precipitation is quite uniformly distributed through- out the year. . The records at Washington covering 90 years show an annual rainfall of 43.5 inches. The greatest average occurs in July with 4.65 inches, or more than 10 per cent. of the annual total; and the least occurs in November with 2.71 inches, or about 6 per cent. of the annual amount. One of the most significant things revealed by an inspection of the precipitation tables is the remarkably even distribution of the precipitation through the year. It is also interesting to note that during the entire period covered by these records—back to 1824— there is not a single month when no precipitation was recorded. On the average, precipitation to the amount of .01 of an inch or more occurs on 10 days out of each month. The fall is now and then excessive, but as a general thing it is moderate. There is probably no very material difference in the fall in the eastern as compared with the western portion of the county, but the records seem to indicate a slightly greater fall in the Patuxent valley than in that of the Potomac. Snow occurs every year, although in some years the amount is very small, amounting to between 15 and 20 inches. Thunderstorms, not infrequently accompanied by hail, occur, especially during the summer months, being most frequent in May and August. The prevailing winds of winter are from the north- west and of summer from a southerly direction. The humidity of the air is not excessive, being probably less than 70 per cent. for the year. The percentage is highest, as a rule, in September and lowest in April and May. The percentage of sunshine and cloudiness dur- ing the year is about equal, the former possibly exceeding the latter by a small margin. MARYLAND GEOLOGICAL SURVEY 193 TABLE II. MONTHLY AND ANNUAL MEAN TEMPERATURES AT BLADENSBURG.* a | : | | 3 | | Ee Moan | os 2 | eS 2 Ey if re : pear Cem ine lien boa ie ale) a Bl Sele 5 ic = = 5.5 se Ti o) Zi a) < 35.5 | 27.2 | 40.2 | 55.5 | 63.6 | 10.3 | 75.8 | 73.4 | 67.8 | 54.1 | 45.4 | 85.1 | 53.6 21.7 | 26.2 | 38.0 | 52.9 | 69.3] 74.6 | 78.3 | 70.8 | 64.7 |...... aed B628 lane. 8. 20.4 | 41.2 | 37.9 | 44.4] 61.7] 71.7 | 75.5 | 72.6 | 67.2 | 56.8 | 43.5 | 34.1 | 52.3 | 37.1 | 27.8 | 39.7 | 51.9 | 60.5 | 75.0 | 77.4 | 73.2 | 64.1 | 56.4 | 97.6 | 37.6 | 53.2 .| 34.6 | 36.6 | 46.6 | 50.8 | 63.4 | 69.9 | 74.1 | 72.9 | 65.6 | 50.6 | 47.0 | 33.7 | 53.8 - og eds Fea | 51.1 |... ..| 70.9 | 76.6 | 77.0 | 63.5 | 53.8 | 43.7 | 31.6 |...... 99.0 | 37.3 | 43.6 | 54.6 | 59.6 | 74.6 | 71.3 | 74.6 | 63.6 | 53.7 | 40.3 | 33.9 | 53.1 33.0) |93:0 | 38.5 | 48.4 | 60.8.) 67.2 | 75.4 |; ....]) 1.1 B76 [ower lace cise | 87.1 | 36.2 | 39.0 | 50.3 | 65.1 | 70.6 | 78.8 | 78.0 | 62.6 | 53.7 46.8 | 83.9 | 53.5 .| 88.8 | 87.3 | 39.9 | 51.6 | 67.1 | 71.3 | 75.5 | 79.6 | 65.4 | 54.0 | 44.0 | 37.7 | 64.9 SDell | GEE) |b Choe} |) deydedé a) CIE Y) yileiols} |) He tI B30) | isco 6AolleosonelGoudalsdooadlononor | 32.2 | 38.7 | 40.8 | 51.7 | 62.6 | 72.0 | 75.9 | 74.5 | 64.9 | 545 43.5 | 34.0 | 53.1 *The station at Bladensburg was among the first established by the Smithsonian Institution. It was opened in December, 1854, and continued in operation until August, 1865, giving a record of about 11 years. Mr. Benjamin O, Lowndes was the observer during the entire period, TABLE III. MONTHLY AND ANNUAL PRECIPITATION AT BLADENSBURG IN INCHES. lise: | | +3 | ~ je ite bod rake le-lee | : if | | & En = 5 > iS) 5 Year. Boece | a ia) | as a alk eles 3 5 | cs | St | eae ceil el) Rome Or le ee Ns SOR SNEIES DEGRA Su ec "|eceees[eaees+| B24] 2.29 | 6-48 | 2-41 | 1-69) 1-96 | 2-20 |.-...- NB iccc doses. sancwies Ieee ors WO lesa alli O19 Le jistererer's | 5.11 | 5.18 | 3.92 | 6.90 |) ded 2543) |. 0c~ Ge ASiilcreyeterere SOB cerm relents ater \cadccdlloganacidoosod| tote || ee eater e th Paciay eV lord Cry lesan aa 1859.. 42950 2291 to.oe 4-60 leaeat | See | 1.16) 1.6% |G. 750) 2295) | dabbles cclacice TSGO Roney cis osillcton calles « Secllne-nteee 2.88 | 6.78 | 3.27 | 2.69 | 3.65 | 3.26 | 3.55 | 8.05 | 2.56 |...... 10 ta op nolneirocmeeen Graton | 2.15 | 2.04 | 6.82 | 2.07 | 2.65 | 4.41 | 4.12 | 8.01 | 2.68 | 1.88 | 0.70 |...... 1A OS e5 eae aore PAOM KOU EeeA Oi deol Maroon Oso) | C410 [ieee | screreccie 2.60 | 2.85 |. ae TSS a eae 2.93 | 6.04 | 4.31 | 5.27 | 3.22 | 3.03 16.60 |.....|... .. 3.76 | 2.45 | 4.04 |...... TET Woda dtonR Groton ae (cece aereenes Boones Ol aonaO-99) S38 1 On74 lec... alert allisen tial lappeea Comaoe SG: Ra Gocmee borin earl 1.32 | 4.08 | 1.90 | 2.97 M92) 2568 tl OVQBal errec } 5 aes E13 a a | 3 Se hei alles | 3 | 35 ° o | 4 5 ey = < = 5 5 | < | 2 Ss Z A | a = eee | Se oe 5 a 3 a, os s peal rurSham| | meotar 1h ch | fe f)2(/2/2/2/3/2 a|5 2 8) < 1901 IU oe acts af aoe 84 | 97 | 100 | 90 | 93 | 8 | 72 | 66 | 100 i “eh iyo tsl lS ceroael Poecantel otocda loan as 39 48 64 ff 42 | 30 V7 0) } enters 1902 ) Max 51 60 78 89 90 97 99 | 92 OZ SOM a aaiG 60 99 Rye dase ) Min 6 | —2 7 28 36 42 55 45 41 | 26 23 12 | —2 1903 (ee 59 | 73 | 75 | 91 | 93 | 90 | 98 | 93 | 87 | 88 | 7B | 52 | 98 es Oaoek Min 10 3 21 | 25 36 46 | 47 51 39 32 15 uf 3 1904 { Max 63 PA \\ Fl | 80 90 93 | 93 93 92 87 66 64 93 ie een 0 |}—2 |} 19 26 4] 47 | 58 52 35 2t | 23 f | —2 1905 | Max 63 49 80 87 7 94 94 89 88 86 72 58 94 Bg te Min.. —6 0 13 | 25 38 47 59 | 5] 40 29 13 1 —6 1906 { Max 72 64 61 | 87 91 93 90 | 92 91 77 7 69 | 93 aay Min 9 6 14 74a) 29 54 53 | 62 50 29 26° | 10 a6 1907 { Max, 74 56 al 83 84 90 92 | 90 89 82 64 «666 92 eeu Min 9 0 20 | 22 36 45 52) 91 B4 188 29 23 | 16 0 | | } | 1908 ne 63 | 64 | 80 | & | 89 | 92 | 98 | 93 | 8 | 86 | 72 | 70 | 98 aes Min..| 10 NOB | ay eee ey Ge sc) | ea) BYE I bby | ae 4 1909 (Maxs.| 64.) O71 | 94 | 8% | 90. | 498° 1) G8, | 98.4) "Si evo: 78 sl eeaeaeege Oe ( Min 10 76 Zl |, 22 34 49 49 51 | 38 | 26 24 6 6 = —— = Average No. days | with Max. 90° or ADOVEIeE oetoe ne Ee 20 0) Oty) Weal 1 4 8 2) il 0 0 0 | 16.2 Average No. days | | with Min. 32° or | DelO Wr he eee eee 25 23 14 | 5 0.3 | 0 0 07 0 3 14 24 1105.3 Aver. daily range | of temperature. 17.3 | 16.9 | 19.4 | 21.8 | 22.0 | 20.8 | 19.7 18.3 | 21.1 | 21.8 | 20.3 | 17.4 | 19.5 TABLE VI. MONTHLY AND ANNUAL PRECIPITATION AT CHELYTENHAM IN INCHES. | | | 2 : | me eel eres ha) gk |e ear. g = sy a = e 5 = | 3 He Stent S 5 ed ) 2) Qo =] 5 = = < = mr iar) < L o A = < SORE soe [PRUs S GSS Sal eos Bee S671 osu: 94 96 93 cS Se CS eS Gee itrnts Cee ee Bae S24, -Sopiseeee) 49) 46 te 22 OT) 625.) Tae ae: UB965.2 se. . [3 Re! eres T2241) *94)) -S4alesdon| 9S} 97 | <920 77 | 7G G5) 97 Pex iris 5 ae Ree 7 26 |. 38} 49 59! 49 37 26 +24 Ginnie. Se ASO7- 15h. 5 jf Max) 64] 58/| 80| 87] 82] 90| 92) 91, 95] 90) 67)| 621] 95 UMineat) 0!) 14) 22) 26) 37.) 45} 55 | 55135) 32) 221 10 0 1S98: 4. oe fMax. 60] 61{| 72 | 80] 92/| 99) 10; 98 | 100; 85. 67)! 67! 104 | Min. 14 2Ve20 23) sei ae 52-1] G04 52) 35 | 27) (97 2 HS99 8 oc eee f Max. 56! 60 74 88 | 94] 101 | 97 98 | 95! 79 7 67 | 101 | Min 4 18} 19} 25] 39| 48}-53| 54) 37 29 | 21 5| 18 LGOO =). eer J Max.) 65/| 70; 68; 83] 95; 93) 103 | 102 100} 90/ 80) 64/ 103 | Min S133 3| 24] 33| 49 274) 152) SO! er SO) | 22 eae 3 HOt eee fMaxt 649755 | 771 88; 89] 99] 103) 92) 91 | 841 721) 661 103 \ Min 7 0 7| 30| 37) 43} 63) 551 37] 26) 14 3 0 O02 = ate fax a 50) 57 | wi | 91 | 93) (98) 101 | 92) 92'| 82) 7 58 101 | Min 8 Py ais (27 | 35) eee) fo2 |) -88-1) 39") 96°] 22 5 5 1OOSE eee {Max 57) 71| 73 | 91} 95] 87} 96) 97| 90| 85) 75! 49] 97 | Min. 10 Se 20) 125 | Sateen ok | -52°1' S84 97 | TT 9 5 TOMAR A tree J Max 62] 62] 72; 83) 94] 97] 95| 95| 95] 89] 67; 58] 97 | Min} —7 7 | 16!) -27 |) $8)) *50:') 56] 50:1) 35} 28! 20) 22 7 OC serra > Br] {Max.| 63| 51| 83 83| 90| 95| 96| 92) 89| 89; 69! 60| 96 | Min 4 L) 38 | 28) 4551749160! 50! 38 | 32) 16.) 15 1 i aay hk J Max. 71} 64/ 63) 89| 96] 94| 91! 93! 92] 80; 69! 68! 96 | Min 8 9| 15) 27) 271 54) 56| 6O|] 49) 25} 20) 12 8 Lee ao ee Max. 76/ 55, 90 85] 87! 90 92 91 + 91) 80} 66 67 92 Min 5 Of} 15) 225 32)) 42) 50} 52) 39} 25) 21) 12 0 190Se a. *. Max 60) 66 S83 | 87; 91 | 97]100| 99) 87] 90! 71 71 100 | Min 5 $] 19'| 241] 30] 46) 58} 50) 39] 30 9 9 8 TS0G Re oo. Max: 62.) 70 |... .- 88} 93| 95 97 97 86 80) 78 65 97 - “ | Min Gay AIS 19' 291 44. 47 47) C35 o ues 5 5 200 THE CLIMATE OF PRINCE GEORGES COUNTY TABLE XVI. MONTHLY AND ANNUAL PRECIPITATION AT LAUREL. | | | | | if | . o | | S Year. g 3 x | = a) Ses lear Baral eest|), (ee ares = C7) co | 5 3 is] ans) o | oO [S| (i cea hel sey | eS | AS te < | | | ] | ROS ele teterers iekedel crete (tlerereralish everest svereusys | 5.46 | 3.42 | 4.66 | 2.90 | 1.60 | 2.70 | 2.30 | 1.55 | L40)|2 0 ses SOG) seers hetero Heer Alles 8 2.60 | 1.380 | 3.20 | 3.15 | 7.89 | 3.76 | 3.93 | 0.65 | 2:60) | 20:20)l eres VSO Fis ei wis tee soles 2.05 | 5.51 | 3.08 | 3.29 | 6.62 | 2.40 | 6.70 | 2.33 | 1.55 | 4.54 | 5.15 | 3.75 | 45.97 PS9S nila sao crtaate 6 3.30 | 0.92 | 2.64 | 2.07 | 4.70 | 0.65 | 1.72 | 7.20 | 0.78 | 3.65 | 2.97 | 4.14 | 84.84 VB99 5 dordveuc svete eteletel aici 1 3.13 | 4.61 | 5.29 | 2.08 | 3.16 | 3.03 | 4.72 | 5.46 | 5.49 | 5.30 | 1.42 | 1.72 | 45.41 GOO eee See mray Wet sPanereke 1.67] 6.12 | 3.51 | 2.01 | 2.67 | 8.28 | 3.90 | 0.86 | 5.23 | 2.73 | 2.75 | 2.51 | 42.23 ao) Oe ee timo erp | 3.02 | 6.62 | 3.50 | 6.18 | 4.05 | 3.17 | 7.49 | 4.36 | 2.98 | 1.83 | 3.98 | 8.48 49.11 TOO DE Goy eee ee ham ee! | 3.15 | 6.41 | 3.71 | 3.11 | 1.88] 4.11 | 2.89 | 3.70 11.42 | 6.83 |3.70| 5.59 | 65.60 ICR canoaoebesacoonel cond ane | 5.50 4.82 | 2.62 | 6.41 | 5.30 7.04 0.74 | 4.35 | 9.88 | 2.33 ' 50.36 QO 4 ee Sh cds Ae rereee 220) ee aa 3.03 | 2.57 | 2.05 | 6.39 | 4.84 | 1.40 | 4.75 | 3.00 | PABYs\aritel| |S agaac UGO5 Sos Bectsmyerer « esoves | 4.00 | 2.55 | 3.02 | 4.52 | 4.71 | 4.88 | 7.28 | 8.37 | 2.67 | 2.36 | 1.67 | 5.83 | 51.87 GOOG Pe eetheseee eee | 3.59 | 2.23 | 5.50 | 3.35 | 2.72 | 5.59 15.78 |11.20 | 0.88 | 5.22 | 1.98 | 3.68 | 51.59 MOOTA Saree cclaoeeeek. 3.28 | 2.43 | 3.05 | 3.10 | 3.63 | 5.30 | 3.01 | 2.42 | 5.90 | 2.12 6.61/| 3.95) 43.80 NGOS awn ee eee: Srpska eerste Meee ml OP Cees OM hess rete lle] Oi Ge alla All. Soin aieliqc mio clae cc clack o 1909................ 3.50 | 3.82 6.73 | 2.38 | 5.07 | 5.41 | 1.69 | 1.21 | 3.385 | 1.15 | 0.98 | 4.47 | 38.66 | i) ASVerag@ertrsiietscts « 3.18 | 3.61 | 3.80 | 3.16 | 3.56 | 4.31 | 4.72 | 4.35 | 3.74 | 3.17 | 2.69 | 3.69 46.30 Average No. of days. | | Max. No. of rainy | (OR Resta eens Sn Caer | 14 11 iB} 9 12 14; 13 18 13 12) 10 1 Least No. of rainy | | | sys aay er cictcces Se 3) 1 6 3 Average Mo. Snowfall. 5.0) 8.0) 4.0) 0.2 with .01 in. or more.) 7 || 8 | 6 8 8; 10 9 6) dal 6 | 8 90 2 ou ow ise oe on ob TABLE XVII. TEMPERATURE AND PRECIPITATION AT UPPER MARLBORO.* 2 = : | | | g “Gr 5 Aa lie gs |. S | e+ She: || aes a ver | 3/6 )2/81/ 8/8/32) 21/3/21 8] 2 | a = | oe jet eee soa < i | | ; | | F(a | Mean Mon- (1893.|..--- et bee ee 61.8 | 73.0 | 77.4 | 73.9 | 65.5 | 56.0 | 42.0 | 37.4|...... thly and } 1894_| 7.8 | 33.1 | 48.2 | 52.7 | 66.2 | 73.1|..... VENOM MOST eae BS O74 35 ay oe Ann’) Tem- + 1895,| 30.6 | 24.5 | 41.3 | 52.8 | 62.1 | 74.0 | 72.0 | 76.0 | 71.0 | 50.8 | 45.9 | 37.2 | 53.2 PEM AVOK Io ILI laspodlod mors |) StsH0) la>nescllancocloacculoodcdoconsjsoceaglssoes scosciibaoa: boca Migs oe ial dota een 90| 97/ 99] 91| 89| 82) 68| 68| 99 EB , { 1893... | Mee [ees ane eee be 384 g52 |" 55.) 55.) 180i 26 | only eee Ee | i804 Mas) 571/62 ese eee i! Usama eee |) FOS MOSES 69 | 59) 101 ee “"* 1 Min.| 14] 18| 16] 28) 40| 45)..... ee Oa inl Pe Lp 65 eae Be |) 1805 Max. 62| 65| 73] 88| 96/100) 96| 97] 96| 75| 78| 67 | 100 ae 9° T nein | 8 | 722) 30.) 39 52)! Si) (504428) S2beoon ais aaa eae | | 225 cetee } Max 59 | 60 FON. «|<. al tyeete ine allie evel sts, 05) Sys cack eee Ata eee Pp tees pe Min 30 if 1 Ya) een Paar enc crcl ea arSTed ls careench iG > Ome Sem adit ona Base: Potale Minin (1S050 sence tne ee ee] 1.44 | 1.57 | 2.54 | 3.80 | 1.42 | 5.45 4.42|..... ahoee CELy eal Gecrlaes a Sets |.3.45)//40487 sou eer P2Ez Leila ee 1563-03274. reswes Ann’l Pre- | 1895. 5.43 1.10 3.50 5.32 4.19 5.83 3.72 | 1.09 | 1.28 | 2.42 | 1.00 | 2.36 | 37.24 | | cipitation .. (1896. 1.80 | 6.8 | 6.29 |....- ooo aoe jesees poo \ieresgre ooo oe oe oe *This station was established under the auspices of the Maryland State Weather Service in May, 1893, and was discontinued in March. 1896. Mr. J. Benson Perrie was the ohserver. The record is both short and fragmentary—two very serious defects from a meteorological point of view. a MARYLAND GEOLOGICAL SURVEY 201 TABLE XVIII. MONTHLY AND ANNUAL MEAN TEMPERATURDS ALT WASHINGION.* | | | ; | | | = | tan : | 4 | | | E Year. Pes eect Wee ye een Wee. tee) So eH SI ay a Gel eS a S ; ae || ey Ss [=| Pil s|a/aje/S |<) [3 |e aA | 4 EM) a5 auece pacoe wall Sel) Caloyielee Syn) 56.5 | 62.4 71.5 | 78.1 15.3 | 67.0 | 51-2 | 42.1 34.2 | 54.6 PA ee oa econ Bove HOD 25.6 38.9) 40.0 49.2 63.5 "3.5 | 71.9 | 7%.7 | 70.1 | 55.2 | 41.7 33.7 | 53.4 é 41.1 | 35.0 | 47.2 | 61.1 | 67.3 | 72.4 77.8 | 76.8 | 68.8 | 58.8 | 39.9 37.7 56.6 39.5 | 35.0 | 42.8 | 54.3 | 64.0 | 72.8 | 77.3 74.6 | 67.6 56.1 | 481 39.7 | 55.6 35.1 | 38.9 | 48.7 56.0 64.3 75.6 | 78.6 | 75.4 67.1 59.8 | 44.4 35.8 56.6 35.4 | 41.1 | 48.8 | 53.0 72.7 75.7 76.8 | 15.8 | 71.9 58.3 | 45.6 | 36.0 67.6 29.9 | 42.4 47.2 69.6 65.5 73.6 79.2 78.0 69.8 58.0 | 44.7 | 41.3 57.4 39.1 | 45.2 | 48.0 | 49.6 | 63.1 | 77.8 | 76.8 | 77.7 | 67.9 54.2 | 48.3 | 39.9 57.3 .2 | 28.9 | 41.5 | 56.0 64.2 74.0 | 73.8 | 74.6 64.8 53 6 | 43.4 | 43.9 54.2 .5 | 38.5 | 46.2 | 55.9 | 64.5 72.7 80.4 77.6 68.9 58.3 | 62.3 | 37.0 56.7 -5 | 29.1 | 46.6 | 54.7 | 62.6 | 73.1 74.3 | 74.4 | 67.0 | 55.6 | 41.9 | 25.1 52.6 gana dee |aec ces l near leeeweslnces ae}ecce nolenso science |e ear or .3 | 33.2 | 46.7 | 57.6 | 67.4 11.3 | 75 9 | 76.5 | 71.2 | 55.0 50.0 | 39.2 56.8 .9 | 37.1 | 41.8 | 56.6 | 63.4 71.4 16.3 | 73.1 66.8 | 53.8 eae 39.5 55.2 “6 | 36.3 | 40.0 | 57.2 | 67.4 | 74.4 14.9 | 73.5 64.5 55.6 | 40.0 | 44.1 55.4 “6 | 33.6 44.3 | 52.8 | 66.3 75.9 | 76.5 76.0 69.8 58.6 48.9 | 34.6 | 55.8 "1 | 37.0 | 46.4 | 10.9 68.1 74.1 | 80.5 "3.6 | 67.4 | 57.5 | 45.1 | 32.4 | 55.6 "826.8 41.4 55.3 | 63.5 70.4 | 78.3 74.5 | 69.7 3.5 | 48.1 | 36.8 64.4 3 26.8 35.2 | 54.3 61.3 | 73.6 78.4 72.2 | 67.0 | 54.4 | 48.8 | 31.5 61.7 5 41.8 38.8 44.9 60.6 70.8 74.0 | 13.2 | 67.4 | 54.2 | 42.1 34.8 52.0 “8 | 30.8 | 41.7 | 53.0 | 60.2 | 75.6 | 77.6 | 14.3 | 66.1 | 58.0 [oak 39.6 54.8 ‘0. 39.2 49.4 | 51.8 | 64.2 70.6 75.4 73.8 66.8 51.3 | 47.9 | 33.5 | 55.0 5.0 | 35.8 | 41.2 | 50.4 | 63.9 | 67.8 73.0 74.4 68.3 58.6 | 44.4 | 36.3 54.1 "9 | 35.2 | 37.7 | 48.6 64.1 69.4 | 75.0 77.0 64.0 | 53.8 46.6 | 35.3 | 53.6 ‘4 35.9 39.6 50.2 66.4 70.9 17.2 | 17.4 | 65.2 | 58.9 44.7 | 35.1 | 54.2 "8 | 32.7 | 48.0 | 53.0 | 63.7 | 75.1 | 75.8 | 73.4 72.8 | 54.7 | 45.4 | 87.7 55.0 "3 35.0 42.4 56.4 61.0 73.8 | 78.0 70.2 68.7 57.3 | 47.1 | 33.3 | 54.4 “4 39.0 | 37.8 | 4.8 | 68.7 | 70.6 | 75.2 | 13.1 | 67.8 55.9 | 47.3 | 31.8 | 43.0 29.3 27.2 | 42.9 | 48.5 | 60.8 "1.0 | 79.6 | 74.7 | 66.7 | 52.4 | 44.2 | 31.0 | 52.4 ‘| 38.1 | 38.4 | 39.9 | 52.5 | 59.7 | 71.2 75.1 | 75.3 | 67.2 | 49.6 | 88.9 | 37.1 53.6 39.3 | 34.6 | 38.9 | 52.6 | 63.2 | 73.7 18.1 75.9 | 68.5 | 57.7 | 44.8 | 34.0 55.1 2.6 35.9 | 48.0 58.2 63.9 | 73.2 74.0 | 76.8 | 62.3 | 58.1 | 42-3 | 32.1 54.8 31.7 33.7 | 35.4 | 56.0 67.4 | 75.4 81.1 79.0 | 69.0 | 55.5 | 42.5 30.3 64.8 - 80.9 | 84.8 | 41.8 | 53.1 | 63 6 | 5.1 | 79.8 | 74.8 | 68.0 | 54.9 | 40 8 40.5 54.8 .| 40.3 | 87.2 | 44.5 | 47.6 | 63.8 17.5 | 18.9 71.6 | 70.1 | 55.9 44.6 | 39.2 | 55.9 99.5 | 28.8 39.1 48.0 63.6 72.9 17.0 71.9 64.6 | 53.6 | 41.0 | 36.8 52.2 . 40.8 | 36.7 | 39.4 | 51.4 64.5 75.8 | 81.4 75.5 | 65.2 | 50.9 | 45.2 | 26.5 54.4 99.4 | 39.4 | 41.0 | 52.9 | 61.9 | 73.9 | 77.8 76.3 66.9 58.6 46.2 41.8 | 55.5 33.5 39.8 | 49.4 58.3 | 62.5 | 69.1 | 80.2 75.0 68.9 57.0 | 45.4 , 33.3 | 56.0 -| 30.8 | 31.6 | 43.5 | 51.8 | 65.3 | 72.9 | 78.6 73.9 | 64.4 62.0 | 45.6 | 41.1 55.1 41.9 | 40.8 | 41.8 | 55.5 | 70.5 73.4 16.7 74.9 | 67.9 54.9 40.2 | 29.0 | 65.6 27.6 | 32.8 | 40.1 | 50.3 | 67.0 | 70.7 17.4 | 16.5 | 77.0 | 62.9 | 47.5 | 41.7 | 56.0 33.2 40.4 | 44.1 50.8 59.2 | 73.8 76.0 73.9 69.1 60.9 | 42.9 | 84.1 | 54.9 99.6 37.5 | 37.6 50.9 | 63.6 74.4 76.8 | 72.1 | 65.1 | 56.9 | 47 2 | 36.9 54.1 59.4 40.9 42.2 50.9 64.4 72.5 74.2 74.2 71.7 59.6 | 44.7 | 36.0 65.1 2.9 | 26.9 | 34.5 | 53.1 62.3 71.1 | 77.8 73.4 | 66.1 | 54.7 | 45.3 | 37.5 53.0 28.9 | 32.1 | 42.0 65.5 62-1 | 69.9 73.9 | 73-1 | 69.3 57.6 | 46.1 | 30.7 53.4 2.9 | 38.9 38.5) 51.6 67.9 72.1 80.5 73.2 65.0 55.4 44.9 | 37-2 | 64.8 99.2! 85.7| 87-4 | 52.9 | 62.7 | 78.0 | 73.6 | 75.8 64.8 52.6 47.4! 87.5 | 53 6 _*The data in the above table were furnished by the Central Office of the United States Weather Bureau. The observations were made under the auspices of several institu- tions. Prior to the establishment of the Weather Bureau in 1870, records were kept by the Smithsonian Institution, the United States Naval Observatory, the Surgeon-General’s Office, U. S. A., and by various private parties. As it is neither practicable nor desir- able to publish all these records in this report, only the data compiled by the Central Office will be used, as these are no doubt as reliable and homogeneous as it is possible to secure. The mean temperatures and the average precipitation given above are those for the United States Weather Bureau record only, and not for the entire series. 202 THE CLIMATE OF PRINCE GEORGES COUNTY TABLE XVIII—Continued. a : 3 = oO = o S 2 : = ~ a 2) ma ma ap + b at Sie | SE Ie WS Me eee es | comical 5 = = < a 5 5 < A) ro) Z =) < NSS Qieeisiscietetets srerore'e cine 39.2 | 31.1 | 43.4 | 54.4 | 64.6 | 70.8 75.8 | 72.4 | 65.6 | 52.5 | 46.2 | 45.6 | 65.1 WS 90 apvete einer © cies! sis 43 8 | 43.4 | 41.4 | 53.6 | 63.8 | 74.8 | 75.0 | 73.6 | 67.8 | 56.4 | 48.0 | 34.2 | 56.3 lS eagencpopnoom onda 7.4 | 41.4 | 38.6 | 55.4 | 61.4 | 71.6 | 72.0 | 74.5 | 70.3 | 54.4 | 44.0 | 43.2 | 5o.4 TSO eee ee ccucieineccres 31.6 | 87.0 | 37.7 | 51.4 | 63.8 | 76.6 | 75.8 | 76.2 | 66.1 | 55.4 | 43.7 | 38.2 | 54.0 UBOS Bens cteloyotescivictens 24.6 | 35.1 | 41.1 | 53.8 | 61.6 | 72.5 | 77.0 74.6 | 66.0 | 56.5 | 43.6 | 38.3 | 53.7 ROL ereretoessvareeiciclstomcrerers 37.8 | 35 2 | 48.5 | 53.2 | 65.9 | 73.6 | 77.9 | 74.0] 71.4 | 57.9 | 44.0 | 37.4 | 56.4 1895.. 31.6 | 26.2 | 41.8 | 53.8 | 62.6 | 74.6 72.8 | 77.2 | 72.4) 62.1) 46.4 | 38.8 | 54.2 IWR AS ABoomoncoCcoS 33.3 | 36.7 | 38.5 | 56 6 | 68.8 | 71.3 76.7 | 75.8 | 67.8 | 54.0 | 50.6 | 35.6 | 53.5 TBO Tiesto taicscte ever levareei= 31.0 | 36.6 | 46.0 | 52.9 | 62.4 | 69.6 | 76.9 73.4 | 68.2 58.0 | 46.0 | 38.1)! 54.9 SGM cse ceieisle) rarcioterete 36.6 | 35 0 | 48.8 | 50.9 | 64.4 | 73.4 78.8 | 76.9 | 71.0 | 57.8 | 44.0] 35.6 | 56.1 BOO ae: deweretewinccos els 33.4 | 27.4 | 42.2 54 0 | 64.4 | 74.3 76.6 | 74.8 | 65.8 58.5 | 45.3 | 36.2 54.4 POO Seicrctaleraterettietevers'ateis 35.2 | 383.7 | 388.8 | 54.2] 64.4 | 72.2 78.7 | 79.6 | 73.6 61.6 | 49.2 | 36.5 | 56.5 YN eta Popeodagaccud 34.4 | 29.8 | 45.0 | 50.6 | 62.5 | 72.4 79.8 | 76.0 | 67.4 55.6 | 40.6 | 84.8 | 54.1 1902.. --+-| 31.8 | 29.8 | 46 7 | 52.9 | 65.4 | 71.8 | 77.0 | 72.6 | 68.8 | 57.6 | 51.3 | 34.4 | 54.8 1908. 33.4 | 37.4 | 50.0 | 54.0 | 64.4 | 67.0 | 76.0 | 71.8 | 67.2 | 56.8 | 41.6 | 32.2 | 54.3 1904. 27.5 | 28.4 | 42.2 | 49.7 | 65.0} 71.0 | 74.4 | 72.3 | 67.4 541} 43.1 | 30.9 | 52.2 POM aelete tes ca Wisreinis tiers 29.8 | 26.4 | 45.0 | 54.0 | 65.2 | 71.8 | 76.4 | 73.6 | 68.2 | 56.9 | 44.4 | 37.5 | 54.1 1906. . «| 40.0 | 34.0 | 87.6 | 55.5 | 64.4 | 72.8 | 75.2 | 76.4 | 72.9 | 56.9 | 47.8 | 37.0 | 55.9 1907.. | 387.2 | 80.2 | 48 8 | 48.4 | 59.2 | 65.9 | 75.8 | 72.4 | 69.4 | 52.0 | 44.5 | 88.1 | 53.5 AGUS ieweeee cn oe 34.2 | 30.8 | 47.4 | 56.4 | 65.3 | 71.8 | 78.0 | 73.2 | 66.6 | 58.2 | 46.0 | 87.0) 55.4 IPOS Se eae esse racce 36.0 | 43.0 | 42.1 | 54.4 | 64.4 | 78.4 | 74.7 | 78.0 | 66.3 | 53.1 | 50.8 | 31.8 | 55.2 IM alaerctavewie arciearciees Sea) Riera 42.4 | 52.8 | 64.0 | 72.5 76.8 | 74.3 | 68.2 | 56.3 | 45.3 pee 4 54.8 | Extreme Mavxi- | mum Tempera- | GUT sees] FO. |) 78) | 193198) } 96 | 102 ah 103 sO 1040!) noe eh ero male Extreme Mini- mum Tempera- | | GureKaeee aoraeae —14 |-15 | 4 | 22 | 83 | 48°) 52 | 49 | 36 | 2b 12 1S eeal TABLE XIX. MONTHLY AND ANNUAL PRECIPITATION AT’ WASHINGTON IN INCHES. fs c | 8 = 2 , Ie esr linear No ae Year. ep [eae tate Clie ee |) ta eel oe) eel iol o a —_ oe | Q © ro] ee all tea Ae) | SS) allies }4|a)o} aja] i | | | | | | UB Q4 oe An crctesctpicreierraa| lOO) nen 65 | 1.98 4.30 | 1.58 | 4.26 | 2.45 | 2.43 | 2.62 | 1.23 | 1.24 | 2.76 | 29.00 UB ZG Gs nota s date Seleeerhe © 1.62 | 2.27 | 3.83 ae 2.37 | 2.66 | 1.87 | 1.35 | 0.45 | 1.68 | 0.24 | 2.76 | 24.45 US26 hiss diese wueyes os 0.60 | 2.01 | 1.68 | 0.45 | 0.80] 1.87 | 2.66 | 2.37 | 1.60 | 1.08 | 2.05 1.62'| 18.79 NORA (isn, Se oe Sa OT 0248) 12.85} ss MeO le2eost |i eee | eve geen cette: T0202. 54a eels eee TS 28 Nee ak te Be ee 1.88 | 3.24 | 3.33 | 4.06 | 3.24 | 1.59 | 1.91 | 1.39 | 1.37 | 1 04 | 0.05 | 0.45 | 23.55 VS 29s ctehe sacle arson cere 6.20 | 2.00 | 2.74 | 3.12 | 2.49 | 1.79 | 7.84 | 5.23 | 3.12 | 1.78 | 3.81 | 2.97 | 43.09 USSG rari erc cae cceee eet a lastnve te fle srk ead eee Jievcvera m]-- a205..5 [opeteceie | hairs, allecetekevallapeleh eal okevenehell ecrereie | eeierets 47.27 DSB Vis hs. 2 aie tasevare eels a [© wisi se aa lol Scmpoy oped eet a cbse | RMR kets tae i ee | | 31.80 EC Tore ete aera eo ceo nc Dee Mee g eeimer || lal DORE a 3.08 | 0.92 | 8.29 3.96 | 3.41 | 1.70 | 35.10 LS SO 2 Hank as Woe SR eee 4.74 | 2.68 0.94 | 2.66 | 3.67 | 3.96 | 3.95 | 6.03 | 1.86 | 1.58 | 4.98 | 1.27 | 38.33 ESS OC chins ayoaes oroudeeeer [3.05}| 2.60 1.90 | 3.92 | 2.06 | 2.66 | 5.16 | 3.10 | 2.13 | 4.70 | 1.70 3.50 [36.47] SA deeds eee oe 6.90 | 1.79 | 5.66 | 4.72 | 2.73 | 2.09 | 3.50 | 4.70 | 1.81 | 3.98 | 2.24 | 4.99 | 45.11 PRED eee! one: 1273/3189) 17511484 | 6.96) Se00 ee serene | emt eee eee | eee es S26 tees tae nee lle OG seloupoeee| 5.68 | 5.02 | 3.47 | 5.44 | 0.26 | 3.36 | 6.57 1.57 | 41.61 18470. coe ce eee ee} 200 | 5222!) 22181 0.82) 1.30 | 2.62 1 St03 1 227914 279i Greta ee bi Dea walspese SAB os see, crt hiserscls oe 1.87 | 1.04 | 1.64 | 0.89 | 2.64 | 2.53 | 5.26 | 1.44 | 1.20} 2,32 | 1.27] 1.14 | 23.24 1852.. 2.45 | 2.87 | 2.53 | 3.90 | 1.13 | 3.76 | 4.13 | 8.77 | 0.85 1.49 | 5.03 | 3.59 | 41.50 WB OSh nae cn aie eee 1.19 | 2.48 | 2.48 | 3.90 | 3.99 | 1.84 | 3.37 | 3.69 | 3.76 | 3.86 | 1.64 | 1.23 | 33.43 1804 eos ee ata 3.75 | 4.95 | 1.69 | 5.23 | 2.55 | 1.57 | 1.68 | 0.63 | 3.20} 1.91 | 3.59 | 0:82 | 31.57 USB Oe tate cases ere 1.69 | 1.53 | 1.51 | 1.04 | 1.34 | 5.51 | 4.15 | 2.42 | 3.13 | 3.38 | 1.06 | 2.98 | 29.74 USSG pacts. heniegae Go oe 3.79 | 0.60 | 1.63 | 2.54 | 3.94 | 5.94 | 3.58 | 3.71 | 1.85 | 1.80 | 2.01 | 2.25 | 33.64 LSS eis is de wade | 1.34 | 0.52 | 1.39 | 2.33 | 5.60 | 5.98 | 4.31 | 9.13 | 1.80 | 2.04 | 1.35 | 5.64 | 41.43 WS58% cma2 wise eset en | 1.89 | 1.31 | 0.95 | 3.77 | 6.90} 1.58 | 4.54 | 4.03 | 2.74 | 2.52 | 3.83 | 5.52 | 39.58 ae ca BY. SURVE a MARYLAND GEOLOGICAL TABLE XI X—Continued. | Ae HOMHDOWDADAINDOONDHORAMMODHOHRHNMAINOHHIOMNONDANOKHNtHHNOMIM 1O WAG ty He lect Aa ies “Tenuu OOO Sd UES 03 00 O22 S209 Bs 1 1 PUD © 00.00 Cs Be 2 00 1 Pk © OB ID OO PS OO CN IO ES Os 1 1) OO CODD | 19) | vies CM al i Vi AM DROW Ar OMONOGHHEADNDAGOIAADNNARHANCOHHHARHHHROMOONHHSS |) SE Son ae G HOD HOD HOD HA AID HHO OAM AOHAHOOMOHHAHAHHAOMHOHOGAHMMMHMHHHHHHOONSEMH bil has as a DHOWD-ORRODENDODRAHONHOANDOONGHHROHOANRNHOMNONDADAAMAMOMG |1o ont a2 oO Ne 00d. BOON) SD OD SSF HOD) HID ED.D V9 EOD CS v4 C19 00 Bs CO) Sh 019. Fa S00. COC >11C19 GD CAE CO ED CNICD OD CDCUICCOCD | et 19) rt HAROM MINA MMINONAONMAMOHHHONANAHAMANOENAANHAOMMANM NAN HOOD 0 Reais z SSOMOOHAROONMDNOADNMOMOWINMANNDDMEMANRDONOHHATNMOOOMMOOD | C> 20 © we AON BS e212 ODN N29 00S O02 00 58 OA RH OD ra SH 69100 00 02 © Bs HH 10D C0 A NINO VCO AC) HOO VOC 1.00 | aici tall teal AMHNHMOAR HHA HAMANDAMMAHANHHMMNRNOONMHHANMMAANMONHHHOO!N Den we TA IODANAAAOLGSHRAROMAMODRODAAAMMNMROANRHNHHHtHHHOHOHRODNORHATHA la 29 at oO S IO GEO es SR ae ESD NIGN S00 16 ES 1CO | 3D OO IE CVD EES, CES SON GSH FA CNCLD dsr 1CYD DLC CO eft Op De Ht OCOD IS Be} Cee tS Ir. AMMO HHAQSAKRHAHAHSSHASISOANONRHAAMHABASCHHHOMANNHOOSHANBAHS | os) Coe oe z, | SAROHHHOSCOCDOOAHDHADDMOONAHMHDANAWDANMDHMHDHOHHHOdTHHOMNHA |o AO tH © POG | AVM MSAQARNVOCH AAO? AAROHAOYAIANAHHAAM AGI AQHACOARAIQOAOY | 19) “os Date wy | WHA ANMOAMIANAMNMORAHQANAMARHONAMOMHMMMAAMHOOCHHNOINOK SD | SS Oe ‘ AHMOOODODODNHAOMANMASRHOOMRHOHOMHHRODNNOOMMORMAMARHNSs+Gn lo CD 1oN A in “ONY | SEEN OH Od IO O10 By 0 ae a Bs 00101900 SH HH 09 6) OND ODOT ONO COIS Crt O0 I ahs FON fh SS eee al ola) APH AAAHAATIONRNONAHADEMAHMAHOANMOINHONAATANMDOMAGDAHASMdisa | + Se) oe NMHODOADON HHONSOHONOHOONOMANBARMHOHHHOOMDOOMNNRYROMONRO [19 MO NN AN Arne 1D 1D OF HOD CD ID YONA AS IIAM MOLI OM ANODE -ATAAVWOMAINOM MOON RIDA AD AOIDNG | © Seq aS int gs | ANDO RARRABNAHOCHAMIODMARHHRMANMDHHMODHAHHIONORIONICOSHON |] + he} oe ik | MANHHOOMHHOHDHOMROAAMONNMMNDOMANHAHOHHHOOMOMOOCOCaNOOMAN 00, TO +t 7H OO OUT L | By AViOO SOO OD reac) 09 vg tC) OS BS OHS D'S) OD CURD Dns 1D WFD 2 O19 PS 2 W'S) KO 19 00. 619.019 0 CDH = CO CH 00100. 00 | rt SHES sien sh Doe HAM HHO MOM MHHANRANANHFOOMMNNDSMONMONHNHRHANHANSQH HM 6dtiodam | ce ae i. 1D 00 DIOH MADCON MNOMHNHNASOKhHONOCOCOAMNSORSMHARHMAOROMAHIMNHNOMOR | ~ QP m0 A A “ABI RN ONQDPADRAMANSHAEADOCOAAHYHON SHOMH HECHSOASSWHOHHANONAHOAN | | es oe CID ODA OD HOMDIDH HOMO AAAIAIAMAONDACANHAGDCMIHOHMIACSCHATAMAA CHIDO oF | Onli * DQM OAM MOHMOOCHHRIOAMRARHDNORMOBHHOAMHAHARHORAOHHHADRWDOMHOD [10) OO mm es oS ady MVD Esc o> Se DONIC ISS Bs HC NSEC 1019 (V9) 00 94S ISS SCN 8 OO IO2 ICUS CNIS 6 AED Gr CNICN IO COI CORD CO) | CN ute less th Cl | HOHIDNOMDMOAMAMDAHHMIANHOANANTHANMHOAAHMMOHMNARHONHANMOHAA | eet es A SHODMDOOD-HDHDANMOONDAHONOKNHAMNAMMOMDHOMNDROONHPRHOMNAHTAGMNO | 19 +o Ot NN ee ole Te KOPP CE CeM err te CAO TNS ETE A TC SONS SMe SOIC Se ORS ATTA Ie Te eto) St SIG IANS Leo) ate nied Wal Ce) DOA HIDIDIDOP ND OID OD OO ACD IDO HAINOM OE HOMHHMDINHONDANHHONAMINMOHAAH | oo Ce wees 7 | _ a ——— a a -- ———— ——- —- — —___ -_____ —— — _— —_——_ - —_ —__—__—_ | rj | ONAHAHROAMNMOCHOAMNMHANOOHHRADHADHMANDHOMDHNHORRHROANNMHHOHHONM | A) er ee ee QOL | STHAAPPWRADRANQOARONOWANHHHOSSVOMHAHAHONOMMHORAOCHRMOBAMAT | +) eo So 4 RE DAAANSAHIAHNTDOHHANMAARHHONMOHHMOONHHMOHHADOCHOMOHOHAAAAHN | oo] oy eS 2 SAMDONMDDHOMOOMNMAONDNKN MAHON RBODHAMNAHHOHNRDAANANHONOnHOH!] KN] SN aN AN oo be ‘uBy’ YB 2D HH OVO 09 41D CO OY ES 08 09. 60 SS 18D rd SD HO 09 2 © UD 4 0G 00 A HNO ID I OI. TCO AO 1D rig Hog | 9 SIN os PE ee he HAM OO HATO AHHANACM HAO HMO AION MIOHIONAHHOMANAHARMHAAMHAMOAON | PS Sy 2 = aes Sap Nan NL oa ae Free ia eS ELROE CATER SIG aa MGSO TTT SEE es I = Sa : a= aS ae ee cts RB Aoi vat Tyce ET te ois Pe, Ci a Se Oe le Ae aa de ee oot ss oe «oS ita of en o Wa fees SpeeC cee aac We sue ae Noha sta Su lors ralans Mos fou Sat lig hie ion cues ere.<. Mo: laitlig's) histy aimee me AANA Weite coriecn oo Pokeastaveu "ys, Go aatci st eae Me eam: aon aE Be Slee = Sirota acs Peete Medie Sgt Sno evar tarot My fumiictn Ceaeta Mec “ens Wet e aie fee) fh a pea Gee Sap oo goe o 26 i caaieaets 22 oat oan gitea Cie PRE Ci ceh, Oee eed oe nee Lr ein en ecirr big ee i eM eae tae oe ate « Oe 280 2a eee Ongey On ioe I MaCcierSSMi: ci OY. Sat Dace At teva ze agate at a siebeas MMe Nake MCE a) Vir vey RAMA opis Ta ee sree ap Ur whe, Sioa ume an eS ahaa 2 QR lg | dre. 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St) “88 80)! 80" GieeneD Ming atte scaectas 15| 10| 2v| 42| 45| 56] 61/ 62] 73| 34| 28]. 2 isp) MO 69| 64) 79] 83| 87/ 90| 93| 90) 93) 75) 65) 7 Miniceneecauccceeee 23| 14| 24] 40| 47| 70] 60) 61) 45/ 36) 20| 15 me Max 73 | 70 |...5..| 8 81) 88) 93) 98 | 90| %3| 63 Minit. . cayactornseceves 15i| V2 Gatos 29| 48| 44| 69/ 68| 60| 29/ 27| 18 is) MAX 65| 67 | 65) 67| 88 90 90 | 90 88| 67| 65| 68 UIMitri Ss sce sbac ween io! 8| 30! 35! 48! 72) ofl ev) 47] 43] 33] 2 MARYLAND GEOLOGICAL SURVEY 205 NOTES ON THE WEATHER. 1753—October : Frost on 29th. Snow on 30th. Thunderstorm on 4th. November : Snow on 14th and 23d. December : Snow on 17th, 22d and 28th. 1754—January : Snow on 2d, 6th and 24th. March: Thunderstorm on 5th, 21st, 22d, 24th and 28th. April: Frost a ad 12th, 13th and 28th. Snow on 20th. Thunderstorm on 26th. May: Thunderstorms on 12th, 13th, 14th, 15th, 16th, 21st, 24th, 25th, 26th, 27th and 28th. June : Thunderstorms on 2d, 3d, 4th, 6th, 19th, 23d, 27th, 30th. July : Thunderstorms on 10th, 12th, 15th, 16th, 17th, 18th, 19th, 20th, 22d, 23d and 30th. August : Thunderstorms on 13th, 14th, 15th, 17th, 18th and 20th. September: Winds for the most part easterly, and very rainy. October : Winds easterly, and much rain in the beginning; latter end fair. November : Winds variable. Snow and rain, ae December : Much rain. 1755—January : Much rain. Snow on first day. February : Much snow. March : Much rain. April: On the 16th it snowed as hard as ever I knew. Cleared up at 2 P.M. All dissolved before night. Not one shower of rain this month. Wind easterly till the 14th, afterwards mostly westward. May : Extremely dry; seldom any clouds; no rain. Every vegetable almost burnt up; strawberry leaves, green plantain and others so crisp as to crumble. In this month many cattle died for want of food. June: Seasonable weather, July : Very dry. August: Very dry. September: Very dry. October : Seasonable weather toward the end of the month. This was the driest Summer and autumn ever remembered. Many springs dried up that ran brisk before. My spring, a remarkably good one, ran very low and the water was unpleasant, November : On the 18th I felt three shocks of an earthquake about eight minutes before 4 o’clock in the morning. The first was severest. It shook the house very much and waked me. The second was less, and the third least of all. They succeeded each other at about the one minute distance, and were felt all over the continent December : On the 16th there was a brisk southerly wind. The mercury about noon at 71°, at 4 P.M., at 69°. At5 P.M. o’clock the wind came from the northwest, blew excessively hard, and did great damage in the country. A prodigious quantity of rain fell. It cleared up at 6 o'clock, but the wind continued blowing hard al] night. At 8 o'clock the mercury was at 43°, at 7 o’clock next morning at 26°, at 9 o’clock at 24.5°, and following morning, viz., the 18th, the mereury was at 15°. 1756—March : No record, being hindered by business. April : Seasonable weather. May : Seasonable weather. June : Plenty of rain. The season much colder than usual. Mercury standing frequently between 60° and 70°. On the 22d, in the morning, a black cloud came from the northward, soon overspread the hemisphere and threatened much wind and rain, but soon blew over without much wind or rain. The sun shone clear, and the weather calm, till toward noon, when clouds collected toward the north and northwest. About 3 P. M. there was the most threatening appearance I ever beheld, the clouds in some places of 2 deep green, in others of a sooty black. At 45 minutes past 8 it began to rain and blow. attended with remarkably severe thunder, but as the thunder stopped the clock I cannot say how long it lasted, but suppose near half an hour, in which time the most rain fell I ever saw. The wind did incredible damage in several parts of the country. In St. Mary’s county, it_is saia, 200 houses were blown down and many people killed. In every county in Maryland much damage was done by this gust, whicn was the most general ever remembered. It was all over New York, the Jerseys, Pennsylvania, Maryland and Virginia, and did much damage everywhere. How much further it extended, either northward or southward, I have not heard, 206 THE CLIMATE OF PRINCE GEORGE'S COUNTY July: August: September: October : 1757—January : February : March: April: May: June: onaliyes August : September : October : November : December : Seasonable weather, and the most plentiful appearance of corn and tobacco I ever saw. The wheat was got in last month. It is supposed there will be the most of any year since the settlement of the country. Very dry. This is the hottest and driest summer ever known in Maryland. There are great crops of corn and tobacco made, but, through the extreme dryness of the weather, the latter crops of neither will come to perfection. Many springs are dried up that were ever current before. The weather seasonable. Many sudden alterations as to heat and cold have been in this month, but the most remarkable I have ever observed was the last day of this month, when the mercury was up to 65°, and the next day, February 1, when it was down to 28°, about the same hour in the day. It rained almost every day this month. A vast deal of rain fell this month. The wettest and coldest April within man’s memory, Seasonable and healthy. An uncommon wet month. The hard rains beat off the flour, or farina fecundans, of the wheat, so that very little of that grain was made this year. Much rain. Much rain and thick foggy weather, Very wet. Very wet. On the 10th of this month there was as severe a gust of thunder and lightning as is common in July or August. Several horses, cattle, ete., were killed in different parts. There were the most luminous coruscations I ever saw, the whole hemisphere, as it were, in a blaze. ; Very variable weather. Many high winds and much rain. THE HYDROGRAPHY OF PRINCE. GEORGE'S COUNTY By ev PAO NEW Ei InrroDUCTORY. Prince George’s County, situated between two tidal rivers, Patux- ent on the east and Potomae on the west, 1s ‘dvained by small tribu- taries of these two rivers. With the exception of the important power development on Patuxent River at Laurel on the northeast boundary of the county, there is no water power of any considerable value in the county, although several small powers on the tributaries are used at grist mills. The tide in Patuxent River, which has a mean range of 1.5 feet at Nottingham in the southern part of the county, flows to the “Fall-line” at Laurel. On Potomac River along the west boundary of the county the mean range of tide is about 3 feet. The soil is generally sandy. The surtace is rolling and hilly and is in farm lands with small forest areas. There is no irrigation. Ture Paruxent River DRratNnaGE BAsIN. This river has its headwaters in Howard and Montgomery coun- ties, and pursues a southeasterly and then a southerly course, form- ing the boundary line between the counties of Howard, Anne Arundel and Calvert on its left, and Montgomery, Prince George’s, Charles and St. Mary’s on its right, and empties into Chesapeake Bay 18 or 20 miles above the mouth of the Potomac. Its length, measured on a straight line, is 80 miles and its drainage area is about 960 square miles. It is navigable 40 or 50 miles from its mouth and crosses the “Fall-line” near Laurel. Its basin includes a hilly anc rolling country with no lakes, and soil of sand and clay with some limestone in parts. The flow of the stream is very variable; the bed 208 THE HYDROGRAPHY OF PRINCE GEORGE'S COUNTY is often rock, sometimes overlaid with a thin layer of gravel, and the fall is quite rapid. There are several important power develop- ments, notably at Laurel and Guilford. At Laurel a total of about 260 horse-power is used, which can generally be obtained during only 9 months, or less, of the year. Of these, 60 horse-power are used in the Avondale Flour Mill and the remainder in the Laurel Cotton Factory. THE PATUXENT RIVER AT LAUREL. This station, which was established August 3, 1896, on the bridge on the main cross street of the town of Laurel, Md., was discontinued August 10, 1898. The initial point for soundings was the end of iron truss on the upstream side of the bridge. A wire gage with metal weight was attached to the lower side of the bridge, the scale being a 14-foot board spaced to tenths of a foot with small nails, and fastened to the floor timber of the bridge. The bench mark is a copper bolt set in a large capstone of the retaining wall on the lower side of the bridge abutment on the left bank of the stream. It is 21.22 feet above zero of gage height. The drainage area is 137 square miles. The flow of water past this station at low stages of the river is confined to certain hours of the day, on account of the influence of the dam at the large cotton mill situated about 1 mile up the stream from the station. In the following table are the results of the several current meter measurements of the quantity of water flowing past this station in cubic feet per second at various stages of the river. Each of these measurements has been plotted as a point on cross-section paper, using gage height and discharge as coordinates and a smooth curve, called the rating curve, has been drawn in such a position as to average in a general way the inconsistencies and inaccuracies ot these points. The rating curve shows the probable discharge of the river at any gage height, and from it has been made the rating table which follows the table of discharge measurements. The record of daily gage height shows the fluctuations of the river from day to day, and when applied to the rating table enables one to estimate the daily discharge of the river. The estimates of daily discharge MARYLAND GEOLOGICAL SURVEY 209 have not been published, but from them the table of monthly dis- charge has been prepared. In this last named table are the esti- mated maximum, minimum, and mean flow of the river in eubic feet per second for each month over which the record extends. Two quantities shown in this table may require explanation. In the column marked ‘“Second-feet per Sq. Mile” are the estimated mean run-off from each square mile in the basin for each month, assuming that every small portion of the drainage area yields its proportionate part of the total flow. This quantity is obtained by dividing the mean discharge in second-feet by the area of the drainage basin. In the column marked “Depth in Inches” is given the depth of water in inches which would result if the total quantity discharged by the river in the mouth were spread out over the whole drainage basin. In Figure 3 is shown graphically the variation in the dis- charge of the river during the period over which the record extends. LIST OF DISCHARGE MEASUREMENTS OF PATUXENT RIVER, AT LAUREL. No. Date. Hydrographer. Gage Height. Discharge, 1896. Feet. Sec. Feet. LP SCD eels verre ewetcweyecetto ane letra leney alist Gs geal sectors esac) oe 4.60 161 DE mINOVAm Oo DrosGunierd ss sclercieiee « 1S 1G Seals tere teteevee.< 0 > 4.40 123 1897. eee HIG Dew lel vevewarotatereneceusiterersi nate salve BE. (5 enn, 65.6. q.ocno mo ot 5.40 184 APE HLG Dy ieye doch cols crete lsiielo erator seeked ING IE NOG IIEEG oma. ood 8.50 612 aie” BNE OS 6 eae eicece cine O Nout Rene Mec 1D, (Gy JEU 6 goncoci oo 4.40 155 (@;. AVG fe As ety Sloencto Cue con miO oon BL (Gh WM Gp ose aoc ae 8.70 734 Co. oUUIR aleian Sip cine oc as Gieceoenc.Ol Gi ee Matthess 3... - T.85 539 Si) Ciel pare esa iniama ceomorcra orc Bee G eaters acieens ois crs 13.70 6144 ORES CPD batd Tents orator ails: ci tcyalleheteusn sere lemeits 1D}, Gls 124 hes otro Ocrero 4.10 a3 1898. id, . UES ieee heuer aoe earacto cee Paul & Matthes........ 5.80 259 GING yet OP Satie sit yee clsne is auracehe BE Ga aes «snore soot 4.90 OT ESTIMATED MONTHLY DISCHARGE OF PATUXENT RIVER AT LAUREL, FOR 1898. [DRAINAGE AREA 137 SQUARE MILES. ] Discharge in second-feet. Run- off. soe. a Second: | -¢ ets | feet per | Depth in bea Minimum. Mean. square TWiGhant ; ¢ 1 | 1898. | | JETDETAY Sone coos pbatcsbeugcededooucoor 34) 94 185 1.35 1.56 February 3's. -1'6 HORS CORD RCEE DEI aEe 23 110 161 1.18 1.23 March. . 347 90 130 0 9 1.09 April.... Be ecinicsiovels =1aus 162 94 Mi 0.85 0 94 WE AVcoqenbes padp dooonocegoee OC oF 630 78 17 1.29 1.49 AWG) Gaoneeeoues ooadunds. Gdeogguonougc 272 59 91 0 66 0.73 ditlhyo" see. 255 | 6 50 0.36 0.41 CEASE lO ken e eeye dreisiccle. sender If eeleDSGaees ie 256 272 *1.99 *2.29 | *Estimated for whole month . 210 THE TYDROGRAPHY OF PRINCE GEORGE'S COUNTY DAILY GAGE HEIGHT OF PATUXENT RIVER AT LAUREL, _ FOR 1896. Day. Jan. | Feb. Mar. Apr.) May 2 = a June July| Aug.Sept.) Oct. Nov. Dec. DAILY GAGE HEIGHT OF PATUXENT RIVER Day. Jan. | Feb. Mar. | Apr. FOR 1897. He SUSU SUS OD DH VOTO Os DI VOUT ON OH AID OOH POON we S (a)Gage down. 2 COT OLN a HR OT OT OT OT OUT OU OT “reponeccre Saiki 1 A TOOTS ROTO HOU RT CE OT 5 o> or cs ao (=) ORR RR ROR RR RR RR OTR RR OLOT HE 80 l ] | May June July POMONA UAW EOTR EER ROTOR ORR RO CO CO o i= 3.30 5 UD CO OTH Ol me mR TOTO TO Bech cee ce Ce Dr tOicecneiO or i=) CO Hm OD HR oo 9 69 ¢ Oe OHI HAOMAWS OS St AT LAUREL, Aug. Sept. | Oct. |Nov. Ste UC St at CCE SS St a OO SS St CC Sal aa oc ae) nw: on Ss BH _o ts) LPP EPROP EIRP PRR OPP EPRER R R Rm OTOT PPR OCR OUR RRR ORO CEPR RR OOOO RRR RR g e = S wore Sororg PPP PE EOPR ERP PROP RP RP ROE ROR RP ROO ~) Ry 3.60! 4.55 10.55 6.30) 35] ROUT RRR RR ROR ROR OUR IR OUR OFoTOUe me OT = He OU HE HR OL DT OT DT OU OT He OT OD OO OT OT OL OT OUST BO He a cakebo th Mate eehle eee, whee bus Maik eitemioguataemielglelse” (a Meir es veh. mii oll stam MARYLAND GEOLOGICAL SURVEY AVAL DAILY GAGE HEIGHT OF PATUXENT RIVER AT LAUREL, FOR 1898. | | | Day. Jan. Feb. Mar.) Apr. May |June July Aug. Sept. Oct. Nov.| Dec. | | | | l | 4.90) 4.65) 5.00, 4. 0 4.85| 4.55) 4.85] 4. Ee 5.30| 4.70| 4.60) 4. i 5.00| 5.05 4.70) 4.48 : 3. 5.00) 4.70) 4.80) 4. 3.90) . 3.§ 5.10) 4.45) 4.60) 4. 3 6 5.15| 4.45| 4.60) 5. .35| 3. 5.40) 4.55) 4.60) 5. 4. 3. 4.90, 4.60 4.45) 5. 4.35, 3. 4.75 4.55 4.40, 4.95] 4.35, 3. 4.75) 4.55, 4.60) 7.25) 4. 3.8 4.60, 4.55) 4.50) 7. Ah) 229 4.68| 4.40) 4.55) 5. 4.20) 3. 4.65) 4.55, 4.45) 5. 6. 2. 4.65) 4.50) 4.75) 4. 4. 3. 4.65, 4.60 4.70) 4. 4. 3. 4.50] 4.70, 4.35] 8.40) 4.25) 3. 4.50) 4.58} 4.45) 6. 4.30, 3. 5. 53h 4.45| 4.50 4.85) 4.40 E(u ooanlloodso lpn o0 oljoo coonljanocc a 5.80| 4.25) 4.50) 4.80 4.20) BuO oc cccclecescrlecsrce|- s+: ecleceres 250 6.45) 4.10 4.45 470) 4.10) B.T5).. 0256) oslee=-==foocen, [ovine es 3 5.75] 4.45 4.50) 4.55) 4.10) BS. 75)... cfeeceecfen ee s[ereees Bas 5.00, 4.35) 4.30) 4.80 3.95] B.40)....e-[ecceecferesesler- 2s] 6. 4.90 4.55 4.40, 4.70) 3.95) ETB cial Weieterets eters seus lerelinvece/s A. 4.85) 5.70 4.80, 4.50) 3.85) SUB capstell eters usta! lstslatele’o||vieloles sik iececeelars 5. 4.75) 4.50) 4.45) 4.50 By BK Us\ecoddd|oononcltocooua|) domnc RAE 4.65) 4.35) 4.385, 4.50) 3 90) -B-B5ice eee foewen [oc cess|eeemasiec secs BD. 4.85 4.55) 4.45 4.45) 4.1B] F.7D ccc clecee cele se ee] cer ecloeeree 4.85) ..0..| 4.65) 4.65 4.30) 4.10) B.QB.. 20. [ew eeecfoseees S11 uigacionstonuD coun Odug ono | 2S ina Geos | 6.68) 4.55 4.55] 3.90) 3.05 ....--]eeeeeefeceeectoceres sa stave 31 [ea Sherrer 5 BDI. tse es 4.451.026. SUBD acc emia neler farsi Scmisleseieae (a) Repair of. bridge. Gage torn out and station discontinued. ESTIMATED MONTHLY DISCHARGE OF PATUXENT RIVER AT LAUREL, FOR 1896-7. o> [DRAINAGE AREA 157 SQUARE MILES. J Discharge in second-feet. Run-off. iat | Becona: | s S F nae : | feet per epth in Maximum. Minimum. Mean. square Waheed: E es 7 ” 2 Se * inch. 1896. | pre Saye a PANG USteee eccemians ss" os) 2 160 | 30 iy 4 0.87 0.98 September...---..+sss:e seers res 203 30 98 0.72 0.80 OCHODEL. cece sce se cn ecce ree tee eee een 165 | 45 98 0.72 0.83 November 247 | 40 | 129 0.94 1.04 December... +-++-:++ ++ 181 | 50 | 140 1.02 1.18 JAMUATY. +2. cece cece sees cee e eee: ve ceee 184 49 | 120 0.88 1.01 February . 2,418 | 140 | 400 2.92 3.04 March.......-- 233 | 110 162 1.18 1.36 April....-+-+:- 329 | 63 | 148 1.08 1.20 IMLAY cnicinis cwisislsieicle evs = aie 1,180 | 90 203 1.48 ily Aphis odo0 ueoddged Cope deDauae be 73 49 | 113 0.82 0.91 DULY. 22s acc ceise ces cece cess 9 50 4,274 | 39 | 320 2.34 2.7 AUGUSE.. cee cece eres crete eee ee 575 | 82 | 145 1.06 1.22 September.... ...0. ceeeees cece cerns 261 25 86 0.63 0.70 WMETO DET eee emeciscisericriiee« (ie) sicle 151 7 92 0.67 0.77 November..:--seesees ee ceeeececeeee 2,035 102 251 1.83 2.04 DeCEMDVEL.--2 20+ vere cesses cee tees 704 98 199 1.45 1.67 WWE Vea iaas: cwete Sear meet “ald 4,274 jie Goan oat 1.36 18.33 intl ee eee BERR ERR MWIEEOLEELEL AAMOAIOUAAMECCUAMAAAOUGRAERAOORLUED EST SE Tae a ain eae a SUMS CREP ONKPTMERSEERUSHEEECZCCORAN Fic. 3.—Diagram showing eee of Patuxent River at Laurel, 1896-1898. From 20th Annual Report of U. 8. Geological Survey, Part IV, page 116. WESTERN BRANCH OF PATUXENT RIVER. This stream les wholly within the boundaries of Prince George’s County, and drains an area of 108 square miles. Its headwaters he to the northeast of the District of Columbia in the northern part of the county; thence the stream flows southeasterly receiving Colling- ton Branch from the east and Charles Branch from the west and empties into Patuxent River near the middle of the eastern boundary of the county. It drains a hilly and sandy country. Below West- phalia the banks are low and subject to overflow. No water power has been reported on the stream and no discharge measurements have been made. MARYLAND GEOLOGICAL SURVEY 2138 ANACOSTIA RIVER. This river has its headwaters in the northern part of Prince George’s and in Montgomery counties, flows southerly and south- westerly and empties into the Potomac River at Washington. Tide runs to Bladensburg. At the District line it drains an area of 147 square miles. Its basin is hilly, generally sandy and in farming lands. The most important tributaries are Indian Creek from the north, Paint and Northwest branches from the northwest, and Beaverdam branch from the east. Several water powers have been developed on these tributaries. No measurements of flow have been made. Other less important streams of Prince George’s County are tabu- lated below with their drainage areas: Stream. Drainage Area. Locality. Henson Creek..... 24 sq. mi. Tidal Estuary. Mattawoman Creek. 47 ie West boundary of Prince George’s county. Piscataway Creek.. 60 i Tidal Estuary. SWENSON So @o5e5c6 24 ‘- Tidal Estuary. THE MAGNETIC DECLINATION IN PRINCE GEORGES COUNTY By e L. A. BAUER. INTRODUCTORY. Values of the magnetic declination of the’ needle, or of the “varia- tion of the compass,” as observed by the Maryland Geological Survey, the United States Coast and Geodetic Survey, and the Carnegie Tnstitution of Washington at various points within the county are given in the following -table: For a general description of the methods and instruments used, reference must be made to the “First Report upon Magnetic Work in Maryland” (Md. Geol. Survey, vol. 1, pt. v, LSOW slang Second Report (Md. Geol. Survey, vol. v, pt. 1, 1905), the various values collected were reduced to January 1, 1900; they are now given also for January 1, 1905 and 1910, and some additional values have been added. The First Report contains an historical account of the phenomena of the compass needle and discusses fully the difficulties encountered by the surveyor on account of the many fluctuations to which the compass needle is subject. T’o these Reports the reader is referred for any additional details. Meripian LINE. At the request of the State Geologist, the Superintendent of the Coast and Geodetic Survey detailed Mr. J. B. Baylor in 1900 te establish a surveyor’s meridian line at the county seat, Upper Mari boro. As the grounds around the court-house were not suitable for ihe purpose, the line was placed on the grounds of the Acadenty. The line was marked by two stone posts, each bearing a brass cap lettered U. S. C. & G. S.; the south stone is 75 feet from the front 216 THE MAGNETIC DECLINATION IN PRINCE GEORGES COUNTY MAGNETIC DECLINATIONS IN PRINCE GEORGE’S COUNTY. ; Magnetic Declination. | s Dat (West.) Lati-| © -= ACOs) | oe eee eS te Stations. | tude Be yee anak Observer. * 15° served. Value eguced te ope sf | a5 served.) 1900.0 | 1905.0 | 1910.0 | Cheltenbam, Mag- | | netic Observt’y. 38 44.0) 76 50.5) 1902.0 | 5 05.4 5 00 ) | ! | 03.0] 08.2 | | 04.0] 11.6 | 05.0 GY 5 16 | | Catoleabare | | Observers,C. &6.8, | | 07.0 23.8 | | 08.0} 28.2 | | | | 09.0] 34.1 | | | | | | | 10.0) 39.0. | 539 | Upper Marlboro, Court House....- 38 49.0] 76 45.2 1896.7 (459.0 5 09 5 26 5 60 |L. A. Bauer, Md.G. 8. Upper Marlboro, Meridian Line.. 38 49.0] 76 45.2 1900.5 /5 05.8) 5 03 5 19 5 42 |) Upper _ Marlboro, | + Observers, C. &G.S. Court House,.... 38 49.0) 76 45.2 1903.3 |5 27.6 | 5 16 | 5 33 5 58 | J Mean. .... | 509 | 526 | 5 50 | Hil dtemegst toe 38 53.9] 76 62.8 1868.8/ 251.1 447 | 505 530 Observers, C. & G.S. Bowler. ania: 39 00.3] 76 46.8 1908.8 / 603.1, 528 | 546 | 611 |} OC, Stewart, EXPLANATIONS, The date of observation is given in years and tenths of; January 1, 1900, would accordingly be expressed by 1900.0 and similarly with regard to January 1, 1905, or 1916.0. door of the Academy building and 58 feet from the fence on the street, and the north stone is on the same grounds, on the edge of the bluff. DESCRIPTION OF STATIONS. Cheltenham, 1902-09.—At the Magnetic Observatory of the United States Coast and Geodetic Survey, on the grounds of the House of Reformation. Upper Marlboro, 1896 and 1903.—In the southeast corner of the court-house grounds, down in the hollow; 15.9 feet west of maple MARYLAND GEOLOGICAL SURVEY Sale tree and 88 feet from southeast corner of court-house; marked by a hickory tent peg driven almost flush with the ground. The mark used in 1903 was the west end of the ridge of a small frame shack about 350 yards distant, bearing 62° 36.6 east of true south. Soil, sandy. Upper Marlboro, 1900.—The South meridian stone is in the Academy grounds 75 feet from the front door of the Academy build- ing and 58 feet from the fence on the street. The North meridian stone is also in the grounds of the Academy, on the edge of the blu. From the South stone the cupola of the Southern Maryland Bank bears 42° 58’ east of true south. The following table is reproduced from p. 483 of the First Report, without change, except that it has been extended to 1910. CHANGE IN MAGNETIC DECLINATION AT UPPER MARLBORO FROM 1700 To 1910. Year Needle | Year | Needle Year Needle | Year Needle Jan. 1. pointed. Jan. 1. pointed. dithatg ie pointed. Jan. 1. pointed. | ate | o- ive |istfa' ¥ 1700 517 W 1750 | 2 26 Ww 1800 0 34 W 1850 Dewi 05 5 07 W 5 OU] 2 OT W 05 0 33 W 55 229 W 10 4 54 W 60 151 W 10 035 W || 60 | 249 W 15 4 39 W 65 135 W 15 0 389 W 65 3 08 W 20 421 W A elo: | 20 0 45 W vi 3 29 W 25 4 03 W 7 | 106 W 25 0 55 W 7 347 W 30 345 W 80 | 055 W 30 1 07 W 80 4 06 W 35 325 W 85 0 45 W 35 120 W 85 | 423 W 40 3.05 W 90 039 W 40 137 W 90 | 440 W 45 245 W 95 0 36 W 45 | 1583 W 95 455 W 1750 2 26 W 1800 0 34 W 1850 211 W 1900 5 09 W 05 5 27 W | 10 5 52 W The declination is west over the county and is increasing now « the average annual rate of 5 minutes. Hill, 1868.—In the vicinity of the Coast Survey triangulation station of 1850. Bowie, 1908.—In an old field in the northern part of town, 350 yards (320 meters) north of the railroad station, 150 feet (39.5 meters) south of Episcopal church, 45 feet (15.7 meters) west of the path leading to Episcopal church, and 27 paces east of smail willow tree on the edge of a shallow gully. The station is about in line with water tank tower and cross on Episcopal church, and is 918 THE MAGNETIC DECLINATION IN PRINCE GEORGES COUNTY marked by an oak stake 3 by 4 by 24 inches (7.6 by 10.2 by 61 em.) set almost flush with the ground. The following true bearings were determined : Cross of Episcopal church (mark) 5° 06.8 west of north. Water tank tower 2 47.2 west of south. With the aid of the figures in the preceding table the surveyor can readily ascertain the amount of change of the needle between any two dates. For practical purposes, it will suffice to regard the change thus derived as the same over the county. It should be emphasized, however, that when applying the quantities thus found in the re-run- ning of old lines, the surveyor should not forget that the table cannot attempt to give the correction to be allowed on account of the error of the compass used in the original survey. To reduce an observation of the magnetic declination to the mean value for the day of 24 hours, apply the quantities given in the table below with the sign as affixed: Month. |. | 7 | 8 | 9 | 10 | 11 Noon} 1 | 2 | 8 | 4 6 | A.M | | | | | Pp. M | =| = =| — 4 | 7 4 | 4 7 | 4 | 4 | 4 4 7 7 4 AEA MUEW Ag c000 codace —0.1 +0.2 +1.0) +2.1 +2.4) +1.2, —1.1) —2.5) —2.6, —2.1) —1.3) —0.2 +0.2 Februarys.ecss.0.- | +0.8) +0.7) +1.5] +1.9| +1.4) —0.1) —1.5, —2.1) —2.5] —2.0} —1.2) —0.8) —0.4 Marci emesccnsto | +1.2) +2.0) +3.0) +2.8) +1.6) —0.6| —2.5) —3.4) —3.7) —3.3) —2.3, —1.2) —0.5 ADVil...eeee-ee ees | $2.5) $3.1] 43.4] +2.6) +0.8) —2.1) —4.0, —4.1] —4.2} —3.6] —2.3) —1.2) —0.2 yer a eceseeee sees | +3.0 +3.8) +3.9 +2.6 40.1) —2.4) —4.0 —5.0, —4.5| —3.6) —2.3, -0.9 +0.1 June.. veeeeee| $2.9 +4.4] +4 4) +3.3) +1.1] —2.0) —3.6) —4.5] — 4.5] —3.8) —2.6| —1.2) —0.2 July ....... ..eee.] $3.1] +4.6) +4.9) +3.9] +1.8) —1.2] —-3.4) 4.4] —4.7) —4.2] —2.8] —1.3| —0.3 MISUSE. oocns 15% | +2.9 +4.9 +5.4] +3.7) +0.4) —2.8, 4.7 —5.1] —4.9) 3.7) —1.9 —0.6 +0.3 September ....... | +1.8 +2.8 +3.4) +2.5) +0.3) —2.7) —4.4| —4.6 —4.2, —4.0} —1.4.—03 0.1 October. .i.0sss 2 | 40.5) +1.6 +3.1) +2.8 +1.4, 1.0 —2.7 —3.3, —3.4) —2.4) -1.3 —0.4 —0.4 November....... «| +0.5| +1.2) +1.7/ 41.8) +1.1) —0.5) —2.0, —2.7| — 2.6 —1.8) —1.0| —0.2) +0.2 December.......-. | +0.2, +0.3 +0.8) +1.8 +1.8) —0.0, —1.6 —2.4) —2.3) —1.8] —1.1) 0.3 +u.1 ANGLE. The angle between the true meridian line and the cupola of the Southern Maryland Bank is, at the south meridian stone: 49> 58 “i of SS: The latitude of the Court House may be taken to be 38° 497.0 and the longtitude 76° 45.2 W. of Greenwich or 15° E. of Wasit- ington. ‘To obtain true local mean time, or solar time, subtract from Eastern or Standard time,’ 7 minutes. inet FORBolS: Ob PRINCE GEORGE'S COUNTY BY EF. W. BESLEY. Inrropuctory. The following report of “The Forests of Prince George County” is the first contribution of the kind made by the newly created State Board of Forestry, under whose auspices all of the State forest work is now conducted. The report and accompanying forest map, show- ing the location and character of all forest areas, is the result of a field survey made in the summer of 1907. The woodlands, which comprise 127,200 acres, or 41 per cent. of the total land area, consist principally of small tracts scattered ‘rather uniformly through the County. In value of product, the forest interests are exceeded only by those of agriculture and hence constitute one of the main sources of natural wealth. Their value is further enhanced by the excellent transportation facilities, and their nearness to good markets. With the serious shortage of timber that is certain to follow the general exhaustion of the main timber supplies throughout the country, and the consequent high prices to be expected, the forest resources of this section are sure to contribute in a large measure to the future prosperity of the County. Tur DisrrisuTion or THE Forests. In the early history of the county the forests constituted, by far, the larger part of the land area. Owing to the demand for tillable land the forests were rapidly reduced, until practically all of the arable land was cleared for the growing of crops. Naturally, along the Patuxent River, (where the tide of immigration first set in) the 220 THE FORESTS OF PRINCE GEORGE'S COUNTY ereatest inroads were made into the forested area, until this section, known in the early settlement days as the “‘Forests of Prince George,” has now the smallest percentage of forest land of any part of the County. For the last twenty years there has been little change. The land that was cleared prior to that time is being cultivated, and the chances are, that there will be little change in the woodland area for a long time to come. In the western part of the County the eenditions are quite different. The soils of this section are more diversified and on the whole, less adaptable to the growing of agri- cultural crops. There are large areas of poorly drained land, also sterile sand and clay soils where pine and the oaks will thrive. Most of this land was brought under cultivation prior to 1860, for the growing of tobacco and corn. Under these exacting crops, however, much of the soil became exhausted and was allowed to grow up in brush. The change in industrial conditions following the Civil War also contributed largely to the increase in the forest areas. In the western section of the County at least, much more land has reverted to forest during the past forty years than has been cleared. The character and composition of the forest has also changed. At first there was very little pine, and there is very little now, where land has not been allowed to grow up as in the eastern part; but distrib- uted all over the western and southern sections where land has reverted to forest, there is a large representation of pine. As a rule the land that grew oaks, poplar, and hardwoods generally was of better quality than that in which pine was found, and hence it was the hardwood land that was first cleared. As soon as any of this land was allowed to go uncultivated it was seeded in a few years by the light winged seed from the neighboring pine trees, and thus added to the increasing pine areas. In many of these young pine stands the old corn rows can still be distinguished. It is estimated that 5,000 acres of old fields have grown up to pine during the past 12 years. In the meantime other changes have followed. Because of the increasing demand for saw material, railroad ties, poles, piling, ete., and improvement in transportation facilities, the hardwoods early invited exploitation. Consequently the hardwood stands have been repeatedly culled, leaving numerous open places in the forest S COUNTY, PLATE LORGE 1 1 C J} tLINCE PI SURVEY. OLOGICAL MARYLAND GE ESTVILLE. > \ FOL AR NE LEST, FOr ITARDWOOD MIXED VIEW SHOWING elle Fr 30RO. {LI AR MAI NE CLASS, SLE CHANTAI OF MEI FOREST OAK MIXED STIOWING VIEW by pean MARYLAND GEOLOGICAL SURVEY Az which have been seeded by the scrub pine. Hence in many of the open hardwood stands are found scattering pine trees of good size, eiving rise to mixed forests of pine and hardwoods. Tue Forrest Types. At first the forests were almost universally of the mixed hardwood type, but under the process of natural agricultural development, there has been evolved two other types, namely, the pure pine type and the hardwood-pine type. The present condition of the forests can, therefore, be more con- veniently treated under these three type classes. MIXED HARDWOOD TYPE. This type comprises 72 per cent. of the total woodland area, or 91,224 acres. The main features are the great variety of tree species represented, and the wide range of soils on which they occur. The composition of the type varies widely with the moisture condi- tions and consequently two sub-types may be distinguished—the upland and the swamp. The Upland Sub-type is found on well-drained soils and consti- tutes much the larger percentage of the mixed hardwoods. There is also a larger representation of valuable species in this class than is found in the swamp-type. On the other hand, the better soils of the swamp (unless very wet) produce a thriftier growth of timber; and the greater freedom from fires, insures a sounder grade of wood. Representative stands in the two sub-types are shown in the accom- panying tables. PURE PINE TYPE. Pure pine stands are found in the northern, southeastern and south- western sections of the County. The two pines represented are the scrub pine and the pitch pine. The pitch pine occurs occasionally on sandy soils along the edges of swamps, but never in sufficient num- bers to constitute a stand; hence as a commercial tree it may be dis- COUNTY E'S | ST CG" wee eee Dimon ooo | whe see ee ste) Were eee ee sees 8000 soli oo ob oO oO Ce er) a olisnet|| ese da pie Co | eralshe cee Jee eeee horoto nn | wereiekers odo ye eae 4 | GG | 0g: Gs" Jesse eoee Rie rsa I= aysitcnone G } | BiB: | Rave sf anal GGG | 69'S | SEF | JAS) | 0S’°s | S4°§ | 6a'9 | 0E°8 Reo ceefeeeees] ego | eee eoee-| eee ele ween [sire ey a Bln ae gue ala =) %°T | 00'T | 1 es og" 0g 0g" | G2'T T | 00°T zw | SLT 00'S 0G'% gL" we CG “Gop alaCae 0S" oS” GG" Zz we aG Go" | $6" Go" ree Go" og" GL- Grell 00°T G 0S 1 cog 69°61 6S Fe 86) GB FE | $3 | 0g" | aera! sae | 93° iG” 00° GG” | 0G" 00'T OG I 0c I I v ce) oO —_ = lees “| @pe ‘| oe: Gi OGG 00°G 0g TI GG to] GE oO) OSNG T] GZ°GT} 0S°8 OO Ooo oe ee enw elvis) scene os) sis 9 = eee eee ee ena ‘0, eile) ee) 80) .e po goo Om oro Oo sae sae eevee vies sine “quod 10g “" [BIOL “66 “CG “FG 256 mo “SI ll “OT Cl Stal | ould /avpep | ATIOH Wd | otdey, ould poy qniog yooog 10) HBO jnuy4sey ynuyseqo AIOYOI poo -BO( BO MOVIE ‘9198 OSBIOAR UB UO SpOOMPAe_, Pax Jo sdAZ pueyd—y vy} Jo uoryIsodwoo T ATd VL oY} SUIMOYS 9[CRL soqouy UStH qyseolg 10}0UIBI(, 2 Vv 99 SURVEY MARYLAND GEOLOGICAL | Peete sl | | | 89° 89° Se) Ocul CGT MOL wee Nae. eGHaGn elves .80n0 | FS 6 ¢cO'OL SG'IT | 26°06 | cO°'t] | °° FeO 4d GZ'OL | OO°FI | G4°FT | 00 ZT | 94°08 | Gags | FIRIOL 1 A 00° 1 00°'T | 00°E | 00°S | Sas | OS's | 0O'F | 00°F | 00°24 ———S= —=— ee Rae Ve tate cel| ie rcarrote swainel| (agen tsieneMe| | aus telpeis cares 50 o.t'a.o Gaalln oa 9.5 aol olor o-caoco ol loorostnty oc ol [Olic.o%o 0 ooo ee ne . elle) citedate hell |veliapetienaietial se! |iajleceie}teiielieiie)|/alie/1e: > |») la/< wie Shige) eve, || |isietiens: = heels OOO) SG Z| Oe wat eecal art, aloes “epee: Pei ea testes) @ze Be aces ee aye eee (Oc | ap: Bue, s cuss Reon iavatitvet [tenses +) Qe: Cz" acon ceecet ‘| o¢ she | ‘| eg: OG: frttt ete] az: Gz°1 | es" | o2°T oc: OD On eee eele Oe Oe Seseenere. iets ee | si otis Spiele: 6) 16;|/at offs] e\.s!\0)\)| 0c° og: 00° T | GL" WG Gach Cz Sarkey-galltk- . SCI A SHOWIN( 1.—VIEW EG CREEK BRANCH, Ss STATION, POPE’ ANDYWINE > ve > ae SHIPMENT, BI > v Fic, 2.—VIEW SHOWING PULPWOOD FOI R. AND W. B. P., MARYLAND GEOLOGICAL SURVEY 220 12 per cent. of the stand, and consists of individual trees scattered here and there. It appears that the pine, in most cases, started in openings made by excessive cuttings in the hardwood stand, and with suitable soil conditions and plenty of light and growing space, it has been able to hold its own. When the present stand is cut, the pine will probably not appear as any considerable part of the succeeding stand because of the greater reproductive power, and more persistent growth of the hardwoods. In general, the hardwood-pine type may, therefore, be regarded as only a temporary one. The representation of species by diameter classes for the type is shown in an average acre stand in Table I. Tur Sranp or TimBer anv Its Vauue. For the purpose of securing an estimate of the standing timber in the county, as well as the composition and character of the present growing stock, the woodlands were mapped and classified in six dif- ferent classes, namely, merchantable hardwoods, merchantable pine, culled hardwoods, hardwood saplings, and pine saplings. ‘The area, stand, and value of saw timber, and pine cordwood for each district, is given in Table V. ; MERCHANTABLE HARDWOOD. It is shown, by the table, that the merchantable hardwood class constitutes but 4 per cent. of the wooded area, but in value of stand, it ranks second. The bulk of it is found in the districts of the eastern section where the soil is of better quality (see map). The merchant- able hardwoods have an estimated stumpage value of $4 per thou- sand board feet, which is higher than for any other class. The higher rate is due to the fact that the timber has been less severely culled and is therefore, of better quality; and also because of the heavier stand the logging expenses are less per thousand feet. The repre- sentation of species, by diameter classes for the average acre is indi- vated in Table VI. It will be observed, from the table above, that while inferior species, such as dogwood and ironwood, constitute a large per cent. of the stand in point of numbers they are of little commercial impor- tance because they seldom grow above the size of underbrush. The COUNTY 3 THE FORESTS OF PRINCE GEORGES a1OTIBIAS | oO -oD qsV 19°S ete ve ONO CHO OW ODd OOD en ee seve] coe [essen efi ee ees i [Lo octttts tee Soe oe ee ee copie Sale oy Eee Ie © eres © iw ol Se a SEES reeee | Qe ieee ee elee ees Siar 3 gq: mew feeeea ci senses] gee [eee eesfee eee] veeeee) gp. ay alle tee toe veeeeel Qge eee ees feeee cele veel ge [eee efeeeees SHE bye zz aie See Oe 68° | 68° wen 19° eee] Bg Core | opr tees] agg eee eG ie CEG Cee SS RO ee) WGA) CO'7 69 G 866 £0°S | 88°6 00°9L Ssh lela see ges a5 ge 6) aac! oie «lene s|.c'|\. 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ARS eRe ane |ary ae wees res" 009ST i0Fc9 I8Z |Lg9e 9696 96h IF OG |FOFET 998E |GL COOL AT WeysutyjoNy eae Fears © has | falas ceite;| Meh ediwte:04]| label at-si/at alll [attasettel (ei lets rei 208 Oo c. ole oAyi SCaF eG 1G80 etelelis)eitshs||\eiee eel e'tel| ll dul'elin jlo exete 100 \) IQ1G [°° * TTT O10qpae yy 14 IGLZT |G 99 |PLST (288 9€66 [SIF 62 {LOOT [0Z0¢ S606 |IF ILSST OZEIL jOSGST IIS {LOFT ae | aking fe a eR SANGSUBPE TE] 6 G9OLLT |FFI@ SSCS |FOLTS [G08 Joes |OL [SFOS |SESTI$ LFF [FE FEsr |BEzETs [COL8E [es [298% SOOT $aes TBO | TT Olftasuey, \ | ] = | = | b eae] Blogs| 2 | es | ee [28 [oBlues) & | ws | oF logs & | ws | oF lees & | us | oF le¥> Ge Sea nC REO Simmer |e aoe lod) © a=; os (Zot g aS Go |woz g ae a soln Ors se 1 Cal oe m fetened ee Cues eer ieia ioe 6 |e lgog| © Be etayer a epereiie te @ |e isog) = PaSlebe ena | oe) eel et | weal all lb 2 | wi ie2e| > | Se | 6. [ees] > | wee [Ses] > asf a Seles et Oe ee Ge |S5\See! ¢ Be Bo lacs! o ac Cui) ae e 5 cheat e oleae eel S0\0 8 | ae los| Sel va vege eee) else (eel eal aes el eel eeeleumene. lamer tei eth | Gee a cuen o Se We eerie er i hall asi eae ee ee | ese JOL.148TC 5e Beles eae cee ees ee ae eee [ce al a es 21° | ge ssul[deg | ssurjdeg SouIq 91qB SpoOMp1IB A | ould SpOOM ouIq |poOmMpieyy) -JUBYDIO| PuB SpooOMpaBH po[[Nny pol[ng | a QByUByOAI | -plvy xl QeyuByo1a py | ‘S}POLISIp AGC PoSuviIe pOoOMpj0d suTd pue J9qUII} MBS JO pus ‘A WTEaViL COUNTY a) ’ ’ PRINCE GEORGE OF FORESTS THE o 2) oO fon ’ ¥e° SP: 16'I | 96° |"" 83° Sr" GF" 96° oe SP" eeee | 8h'S | 06° T Rein co G e| eee | sills 2 + ai) all oio.cee ee eee wid) ee s)/\suee 0:0) © eee OOO on seas rece] ge cree elees eee! gee prunes] aoe | Th: SF | 6I'I 6LL | Ze atdeyy | uns pey | HORT bella I~) @) 6)\6!0) «| »)|\ 0) 0 © 0) ©» 42 0 © ee ee ele ee oe sees een ele eee sae Lisauereiei|\nislelele alae isste | | | vores] gps Beeler 8 [2° | 8h° | SF oth SP [Uae SSE ra ore seeeel ag: | Tp: 88'6 | 6I'T Ze | SF" Je ceoes op acca ye Wale eee se «| (2° see eee Gobo: COR Ios OSes aoa ie aS eines We IL” ‘elt pod G 06°T | FL°G be 9876 4 RO Ov 66 OL 96°S FG" 1 Sr" | G6" 06° I | SF" ce | 6L'T SP WA 99a eGieal | FL'G SV I 99° 1 rel dod) [62 | 21 6 [L°06 | MOTIOA ‘(sjojd ofdues [{T) a108 ‘e198 9UO UO JoJOWMIVIP Ul JaAO puBw SeyOUL Z Sefseds Jo UoTe}UeSeIdeI SUIMOYS 9IqQR], ‘SSVIO GOOMGUVH AIWVINVHOUWIN— "TA WIAVL ZF JO ssv1ldAV 6G && Ze" OL ae oG ve ee teeetlasecete [iv em een el oceee oe anoul| ao eneweslteveiteuenstatetes! ees ; ee | | | SF BARS calle Ae geet ea ate LE? | #3" I Neyaenetestcsiaigell arses ats ae Beet | Vee si ssial as ore SrA Coen, ea ae AERA iz renee Ik: Resi ioral eee QF" De Oc sale eoerlece acl ee . . . © oll.e © evle%e se. | C5" | OF° | ; Sia! sees! Wee | aileirelis) ike inet|\eiio) wiuelis ei coave srohoie 9 | £Z" lee a e| auelese tt ies JES les ee . eleeee srk | we 96" Bee bers Pe ee es ee as = a ee De BR ey tecres i: | #e° Site PR Mcrae tae Sear nee Set || he aie ea nies Mee ya : 06°L | Fa" Senne One| Glob. ROleae —o| tes #G GG : ae EL? 8628 98 | 96 9 | 08'S GO 6L Cte sone ve PS" feesoee +z" eau : | a Goo nis a" OOCU mE a" ses PG" We tz" Sera. FZ sc, eho agens Sh° C6" G6" 6L'L SPT ae GOS 99° T 88S Z9°S (are 18:8 -ys0UO | ALO | |--"4ue9 eq * L9JUUBIP ur 1aA0 pue ‘ul OL Pe=qua) «dary + TRIOT, +890 lke gr on rye 92 ee 2 inh. * | toma Bees “a0 OES & Fetes neeegy ofa alesse Oy beeen ese ngy ac HT dcieieas ciesey nt Bue \FevedisKeleesiexscae [fiekerctohsherancG) rt Sree arr armciOcy gy | G | ee eese ope | soqouy STH WsvoIg | qoJOUIRI] MARYLAND GEOLOGICAT, SURVEY. PRINCE GEORGE’S COUNTY, PLATE XII. Fig. 1.—vIEW SHOWING METHOD OF HAULING PILES, NEAR SURRATTSVILLE. Fic. 2—vIEW SHOWING YELLOW POPLAR LOGS FOR EXPORT, MULLIKIN STATION, POPE'S CREEK BRANCH, P., B. AND W. R. R. MARYLAND GEOLOGICAL SURVEY 229 stand of saw timber 10” and over in diameter as shown in the lower line of the table is made up principally of white oak, red gum, pin oak, yellow poplar, black oak, hickory, chestnut, and beech. The average stand is 3,642 board feet per acre, and the area covered by this class is 4,552 acres, giving a total stand of 16,580,022 board feet. This represents very nearly the amount of timber that is immediately available, and indicates where the stand is sufficiently heavy to warrant logging operations. MERCHANTABLE PINE. The merchantable pine class, constitutes 13 per cent. of the wooded area, and exceeds that of the merchantable hardwoods over twofold. Most of it is found in the northern and southern districts, with but little in the central part of the county. The three leading centers for merchantable pine are Lanham, Piscataway and Cedarville. The average stand per acre including all trees 4 inches and over in diam- eter as merchantable, is 13.52 cords. The total stand of merchant- able pine on the 16,799 acres of the class, is therefore, 227,134 cords. This valued at 60 cents per cord, standing, gives a stumpage value of $136,280. The pine with its associated species in this type is shown in Table ITT. CULLED HARDWOOD. This class of stand represents the mixed hardwood forests that have been culled severely until there is little left in the way of saw timber. The average stand per acre for the 70,868 acres of the class is 1,104 feet, board measure, giving a total stand of 86,188,000 board feet. The stumpage value of the stand at $2.50 per M. is $215,470. The culled hardwoods are more evenly distributed over the county than any other class and exceed in area all the other five classes combined, representing 61 per cent. of the total forest area. The composition of an average acre of the stand is shown in the accompanying table. CULLED HARDWOOD AND MERCHANTABLE PINE. This type of forest constitutes 10 per cent. of the forested area. a al . 5 a . . The stand per acre is 416 board feet of saw timber, and 3.94 cords COUNTY x B a x G PRINCE GEOR FORESTS OF THE G6 Mian MeO Oy Se ey Pee OO Gre eGre0s TOG mL One eee) SG"r | | | Lo°T (6h°8 GE'F 69°6 GSS [81 81°96," **9UeD, 10d SV ine 097 OG) Geedie ss POST 6s | MZOeELSs (GP OL orig hk SS iSise Geo Seo Pa0) GbGrGs60 ba9se) Inescl| sestono | puew ‘ul Of 8G" (0&° Sh 8G" |249° FL" [82° G8" (OS TITS" 116E° 11G0° 203 ses ZrO'S 66'S [&6'F \08°F 6L°¢ FL \66"L [G0 8 |86°8 |99°6 96°04|" * *FUID Jog | | FZ OT TEL" LFS“ G09" G68 SFO SOE E20" GL8°S9T "9126" 2E9 SSL 6Z8" LIFS ZL OF 9LE9" STIZs °ZS|L0 BES" OS 1S" S06 TSILG ZEFG TS °° 12300 = oe | eae o. . oss o. eEelsice | Bai renecta) eeslenewes ith oi oO OOo O PR ee OC PRB EI SoH . ar . wee ree ce tyge [eeeefeeesfecee] ceefeeecdees so] Sno oe pons SNlato.cublloksoilincor cle cpa veeleseeslyge feces feeees . see . ote oe oe ae -CL° srleee wee elenes Pomolo orm olka c ollero to colon oO 198° pote tel ea cage 2G e),p rer ens | eee ele ae Op easy ce ITS" | ai fene Oech Or) ett oe ()ee 163° iGe* Scent eastern IH F(a | a ailecto — 1's Soll alle alleges Ao val 6" 10° cy coe ecloe ee slage Ail : (03 0 0 oie OS0D sae ences eral eaeaa tee ee ID Fal (Gc Je ee elses elecees aa gO aiedenel|teere | 26 olf cole aoe Dafne tr mse Desc cont st (@C)itie |e eiazel as Gian, leva P ize Isc: PLT 10° OL’ G61 glee "20° OG Gh a lie alte 0s (25 GG) 2ealSO. CheanGO Co SGs— Ics ie OGean GSalenGoull G6" T ISO°T |FO°TL |F8'S | ZOE iG Gh Gr. Le) eGe Cie re 0SeaZOo ee ber NTH Crt OeGalerm el GO do iGcrcure ler leCO Vue ems a 2G a lt! ~ q “7 "|" GL" 8h" Sh 6G" |" " OL” 16a" SS | °° Sh GO TOS Tee 1 OST |I8°T \68"s |e" ($¢°S [8@°S 66'S 06° T 9S" OL°9 | °° ie GT" |?" "166° 120° |" °° 198" |= "120° 164° 108" 166° Sh OS" |G" TirZT ISZ° 6S |60°T (96°T \6°T \09°S |G9°S |ZF'S [66 @ 96°8 | “G SP GL” |S" | * "| G9" | Sh OS TEL 166° |6Z° (BE°TIGO' Tie" 29° \29°E |GL°S IZ6°S (09'S 6E'°F \28°S |42°¢ FES S46 | °° Go" jsG° | 1G9 =|" 08° 1G9° | -° Gr LOS LO cies" [09° 168° ace" I I68°s |€9°S PLZT 00° 8° 96°9 99 T c'6 STZ PS Ell CS IG" I&h" ea" 166" ITS TSO" 2S"ci9s" TO LOL” I¢¢" Sich ISE"Sl' "Ish" I88°% IGG" T S'S 198°6 [S88 ise"¢ Isc’ COMIGGi OL Gt GG eG wa| Q | io} | || er) Aue | z ee a oF WelBe|oe| & ie ee od | Staats ee | eu | Cp |iOe ieee oe | oe of 2 ee OS saa SL SEW Dy | plat || yey |] || te Ee |8a|/2E! oie | o Onell st BS | 22 )8o0 | © |) co |] 2] ge] #5 o poa| &= | {ouy iB ee | ar |e Bel eO| © log | Re] Fels ee || lar | oe | AR | we) we) pe | ro a ah to), | ne AS | YSIH ISBOIT ry Sale 8 2|a Beulser| a 5 2 } | ele > © | 1I}JOUIVIG a | Sl ea | ee | | We | | ct | ‘(sjojd e[dwues Ge) saloe ge, Jo oSvisaAy ‘aioe ouo UO JoJEWTRIP UI 1eAO puv SseyoUT Z setoeds Jo Uor}e}USaIdat SUIMOYS JGR, “SSVIO GOOMCGYVEH daTTN) TIA WTaViL MARYLAND GEOLOGICAL SURVEY YQ 23 of pine wood, with a combined stumpage value of $2.40 per acre. Large tracts of this class of timber are found in Bowie, Vansville, Bladensburg, and Piscataway Districts. sentation of species by diameter classes on an average acre. TABLE VIII. Tabular summary of standing timber and its value. Area | wood | Cont. | District _ Of. landin | of | District, District, | Wood- Acres Acres | land 2 a Sas Vansville I.... 23,083} 12,492) 54 Bladensburg II.. 8,806 4,481] 51 Marlboro III...| 15,360, 4,134) 27 Nottingham IV.| 24,678) 7,272) 29 Piscataway V...| 31,149) 17,127) 68 Spaulding’s VI... 14,605 6,199 42 | Queen Anne Vil. 29,581 6,723} 23 | Aquasco VIII...| 19,866 9,448 48 Surratt?s IX....| 17,683) 8,329} 47 Wanirelm@Nes ee ee: Ce 2,982) 38 Brandywine XI. 28,595) 16,833) 59 Oxon XII...... 12,122] 3,736 31 Kent XII... .... 21,645, 7,389; 34 | Bowie XIV..... 24,742} 13,9871 57 | Melwood XV... 19,571 3,986) 20 Hyattsville XVI.| 7,501) 2,082! 28 otaleaeees 306,872 127,200 41 Total Stand Stumpage Value | Table IV shows the repre- es Pine | | Value Total imber, Cord- Saw | Pine M bd. | wood | Timber | Cord- fits Cords | | wood 5,845 46,820 $14,565 $26,481) $41,046 2,444! 29, 886) 5,902 Se 18,846 5,265 O| 14,673 0} 14,673 10,106| 4,326) 31,063} 2,596, 33,659 13,052 56,851, 34,594 31,809 66,403 4,397 3.198) 10,868; 1,449) 12,317 9,864, 416] 30,236 200 30,436 7,883] 22,892) 20,096) 13,656, 33,752 6,341 14,952 16,297, 8,971] 25,268 2,034 3,509} 5,135] 1,912 7,047 13,368 20,321 38 nud 12,005, 45,719 3,688 2,803} 9,220 1,682 10,902 6,180 26,128) 16,589 15,054) 31,648 9,675) 41,596) 25,506 21,770 47,276 5,180 = 1,528) 15,365) 914; 16,279 2,522; 6,907| 8,121 4,085] 12,157 107,838275,128 $291,944 $155,478 $447,422 | HARDWOOD SAPLINGS. This class of hardwoods represents the young growth under 4+ inches in diameter and, therefore, contains no merchantable mate- 232 THE FORESTS OF PRINCE GEORGE'S COUNTY rial. Where hardwood saplings occur, it is an indication that close cutting has been practiced, especially in the cutting of cordwood, resulting in a young sprout growth. The total area of this kind of growth is 8,604 acres, or 7 per cent. of the total forest area. PINE SAPLINGS. Young stands of scrub pine, in which the average diameter of the trees is under 4 inches, are designated as pine saplings. This class comprises 6,975 acres, or 5 per cent. of the total woodland area. The area of pine saplings in each district is a fair indication of the amount of land formerly cultivated, but which has reverted to wood- land within the past fifteen years. The stand and value of saw timber and pine cordwood is arranged by districts in the accompanying tabular summary. The accompanying table shows a total stand of 107,842,000 feet, board measure, of saw timber in the county, having a stumpage value of $291,944. This includes all trees 10 inches and over in diameter measured at breast height (or 44% feet from the ground), and is equivalent to a diameter of 12 inches and over on the stump. The total stand of pine cordwood is 275,128 cords, representing a stumpage value of $155,478. This includes all pine trees 4 inches and over in diameter breast height (41% feet from the ground) or about 5 inches and over on the stump. The pine found in the county is almost exclusively the scrub pine which seldom attains the size of saw timber, and hence practically its entire use is for cord or pulp wood. The stand is therefore expressed in cords. ‘The value of the stand if based on stumpage prices rather than on the market prices of the delivered product, because the latter varies so with local con- ditions of labor, transportation, nearness to shipping points, mar- kets, ete. Under prevailing prices, however, it is estimated that the total available supply of saw timber would represent a value of $1,295,000 delivered at the nearest shipping point, and that of pine cordwood would amount to $850,000, making a total of $2,100,000 as the value of the present merchantable stand, cut and delivered. The timber that would go into poles, piling, and railroad ties is not separated from the saw timber in the estimation of the stand, MARYLAND GEOLOGICAL bo ey) Co SURVEY because the amount so used represents a relatively small part of the output. List or Native TREE SPECIES. CONIVERS. Common Name, Botanical Name, i, Soa) 12h oho oso bas cdocoodadeaoS Pinus virginiana (Mill.). oD. Pare. IPM oooucousoebo sooo oO a0 Pinus rigida (Mill.). @ Slave? IP. srowovoatonovndocG Pinus echinata (Mill.). A TRevsl (Cre, cocpontsagecsoopamonUT Juniperus virginiana (Linné). HARDWOODS. Common Name. Botanical Name. i. TEORONUNe oooboneheoee Fado Od adc Juglans cinerea (Linné). (&, inileyelie Wralhnititeccoag ave agccocgouns Juglans nigra (Linné). Te [BbtMerhole Inli(el Colon og nooas omodo0 6 Hicoria minima (Marsh) Britton. Re Wloyelidaotiin JebiGigomyso ons cuoduoe ods Hicoria alba (Linné) Britton. O) IBicribie Ilya esoohacgcsusumnGUE Hicoria glabra (Mill.) Britton. IO), Wows \WWAUNON Yo 65o6coccocooadao0o00 Salix alba (Linné). i, Ilaelke wWwyrilloniooescsssooundoaooDGc Salix nigra (Marsh). 12, IbATEe wal ANS NG ogesgssoudceo0° Populus grandidentata (Michx.). TSR: Reem ISb ol Ov Sie cemoreicen co cine omic co Betula nigra (Linné). id, Siyyeee, Bel .sacoanaccsncdcopebonce Betula lenta (Linné). i), JB lbeY JSeeYellhe dels on coo oono doco OT Carpinus caroliniana (Walt.). (R, TEV ecto cts 6 SOE oO EIA Ose comico © Fagus atropunicea (Marsh) Sudw. 7, Clnoowenin SaccsoonossccGogugcocc Castanea pumila (Linné) Mill. nf SOM COUN S GINUCe che. cys, oe aileue 1a ei sitelloxelle 'e) eslonoionetonra Castanea dentata (Marsh) Borkh. 10, Wane Onilke. Segopeoceuee up apeco coo Quercus alba (Linné). OD): Itosit, ORNs o 5 7 Oe Oe Oro crane coc Quercus minor (Marsh) Sargent. Pil, Onwaeeurgy Oplkoesoeaeempa cds somoobdc Quercus lyrata (Walt.). PR (Clnasinuiy Ono eaeiencomia cia ciocecn oo Quercus prinus (Linné). Mer, Shimano Wylautwey CRY a eo ons domeoon Quercus platanoides (lam.) Sudw. DAR COW O Ake sme. cisco acokicketorete. scale atate Quercus michaucii (Nutt.). PAR lRvetel “OVN So o Scie ORI 6/0. cer Quercus rubra (Linné). OAR, iselep, (OI oo hemo ed oo eating be Quercus coccinea (Muench). Off, MEEK ol Se (OP to: ctorato a eeces, ateretie Caeyo Old Quercus velutina (Lam.). ZRSES Pp als hee Oa keene. steers tone cites: ast oucllors ven Quercus digitata (Marsh) Sudw. OO NEP im | Oalkacraess id crete sea sev stale etopdine! ersten Quercus palustris (Muench). atl), iBilevolke dievolk (RIK. = ogepoupacdnodaac Quercus marilandica (Muench). Bile STS LOY (Oa Kecrretene, siepeusscisysicters «ten ebebeuete Quercus imbricaria (Michx.). SOMONVGINO Ws Oalkedercncvacsizcs cve.s: « Ss) Fa, i.) =} i=] = ior co ie 4 ta ches stats eehctane ene Ss Viburnum prunifolium (Linné). Tue Important ComMMERCIAL TREES. The Oak.—Of the fourteen species of oak found in the county only white, red, black, and pin oak are of much importance. Of these, white oak is more common as well as being of much greater value. It oceurs on all soils, and is frequently found in almost pure stands. Large trees are in demand for saw timber, the best of which go into bridge plank, car stuff and wagon stock; smaller trees are cut into railroad ties. Red oak saw timber from large, sound, straight-grained trees makes excellent furniture wood and is substituted to some extent for white oak. Only occasional trees are found, however, that are of suft- ciently good quality to produce valuable timber. Since it is a much bo (Se) Cur MARYLAND GEOLOGICAL SURVEY faster growing tree than the white oak, and is one of the valuable woods, it is a species to encourage in the forest. Black Oak is usually found on the upland soils where it makes a slow growth and does not produce as good lumber as the white oak, or red oak (though it is often classed as red oak on the market). Its principal use is local, and most of it goes into framing material and rough lumber. Pin oak is a swamp tree, and in such localities it should be encour- aged as it maintains a rapid rate of growth and makes straight, clean poles, and clear logs, when properly managed. Its principal use is for sawed lumber and for piling. On the lumber market it passes for red oak. The Chestnut.—The chestnut is a rapid growing tree that fur- nishes desirable wood, useful for many purposes. ‘Tall straight trees up to 20 inches in diameter are in demand for telephone and telegraph poles. Large trees, as a rule, suffer from “wind shake” and do not produce first class material. When sound, however, such trees are cut into dimension stuff, boards, or sawed railroad ties. The smaller trees are largely used for hewed railroad ties, and for fence posts. In growing timber for quicker returns, the chestnut is the most val- uable species in the county. It is, therefore, a good tree to encourage on the farmer’s woodlot. The Yellow Poplar.—This is one of the most valuable timber trees and is found scattered sparingly through the forest, particularly in the deep, moist, well-drained soils. It is a rapid grower, similar in this respect to the chestnut, and attains a large size. Large trees bring good prices for saw timber, and smaller ones are largely utilized for pulpwood. Yellow poplar will not come in under the shade of other trees, and consequently it is being gradually crowded out of the forest. It is one of the best native species for commercial planting on good soils. The Scrub Pine.—Of the four pines that are found in the county, the scrub pine is the only one of wide distribution. It quickly comes in old fields wherever there are seed trees in the vicinity, and for this reason it serves a valuable purpose in producing a crop of wood 236 THE FORESTS OF PRINCE GEORGE'S COUNTY on land that might otherwise be unproductive. The tree does not ordinarily attain the size of saw timber, but it has a wide use for cordwood, and much of it now goes into wood pulp. The Red Gum.—This species is found in the swampy locations, particularly along the Patuxent River, where it often occurs in pure stands. Until recent years red gum had little value, but now it is used largely for veneer in the manufacture of berry and peach baskets, and is also used for wood pulp. For veneer trees over ten inches in diameter are required, while for pulpwood, smaller mate- rial is merchantable. The Hickory.—ickory is abundant in the upland forests, but it has a limited commercial use. The best butt cuts are used for wheelwright stock, but there is not much shipped out of the county. It is a slow growing tree and under prevailing forest conditions is not likely to increase in importance in the future stands of timber. The Red Cedar.—The red cedar seldom attains normal develop- ment in the forest in competition with other trees because of its slow growth and intolerance of shade. It is, however, an important tree in old fields, and along fence rows, where it finds ideal conditions of growth. The wood of the red cedar exceeds all other native woods of the county in durability and is hence extensively used for fence posts. Its greatest competitors for such use are locust and chestnut, which are much more rapid growers, but owing to their lability to insect attacks and fungus diseases from which the cedar is apparently immune, it easily maintains its supremacy. Tur Present Use or THE FORESTS. LUMBER. The lumber production of the county for 1907 was about 4,000,000 feet, board measure. About 75 per cent. of the output was used locally. Nearly all of the original stands have been lumbered, and what is left is being cut by small mills, of which there are about fifteen now in operation. The present annual cut is about equal to the vearly growth of the forest, and can be maintained for an indef- MARYLAND GEOLOGICAL SURVEY. PRINCE GEORGE’S COUNTY, PLATE XITI. : E F % 5 ; 1 \ / ; dpi ‘ \ : [ t Fic. 1.—VIEW SHOWING YOUNG FOREST, RECENTLY BURNED OVER, NEAR SPRINGFIELD. SURRATTSVILLE. WASTE IN LOGGING, NEAR Fic. 2.—vVIEW SHOWING CULLED FOREST AND 9347 MARYLAND GEOLOGICAL SURVEY _ 237 inite time; or greatly increased, under conservative methods of lum- bering and of forest management. Oak is the principal species cut, and of this, white oak constitutes much the larger share. Good quality of white oak brings $18 per M. at the mill. The poorer grades sell for about $15 per M. White oak car stuff of first quality brings $28 per M. delivered at the railroad. Most of the white oak is cut into bridge plank and framing material. Some of the best of it goes into lumber for freight cars, and some into wagon stock, which is exported. Yellow poplar is eut for weather boarding, and for general uses. The price of the better grade is about $16 to $18 per M. at the mill. All of the oaks and most of the other species are eut into rough lumber and used locally for building pur- poses. The price at the mill ranges from $9 to $15 per M., depend- ing on quality and accessibility. CORDWOOD. The annual eut of cordwood for shipment out of the county is about 1,400 cords, of which 1,000 cords is pine, and 400 cords ?s hardwood, principally oak. Pine is worth $2.50 to $3.00 per cord delivered on cars at the railroad, while hardwood is worth $3 to $4 per cord. Practically all of the cordwood exported goes either to Washington or to Baltimore. PULP WOOD. Serub pine, yellow poplar and red gum, are the only species cut for pulpwood. In 1907 about 3,000 long cords of scrub pine and 500 cords of yellow poplar and red gum were shipped. The price of stumpage depends upon the distance from the shipping point and the species. The stumpage price of poplar and red gum is higher than that for scrub pine. The items making up the average cost of pulpwood, f. 0. b. cars, where the hauling distance to shipping point does not exceed three miles is about as follows: Yellow Poplar or Serub Pine. Red Gum. SUUMMMP ACR ake co s.ctisis s,00 w cde e cusseimtenevedeten a! shexe « $0.60 $1.00 Cutting. peeling and jpilimge yee eee ee} - IL Wares) USTED LIaEl Ss ieee ee eee een corer ciclo 1c. 0 Cane 1.85 1.50 OAC? MM GALS)... <5 5.5 ener tmetert ce << 20 .20 ANG] Sie Ars a. cee rr $3.90 $4.50 238 THE FORESTS OF PRINCE GEORGE'S COUNTY Under the foregoing prices the pulpwood shipped in 1907 had a value of $15,500 delivered at the nearest shipping point. RAILROAD TIES. The cutting of railroad ties has been an important business in the county for many years. Most of the tie material has been taken out, however, and now the production is limited. The principal species used are white oak and chestnut, with a small per cent. of mixed oaks, including the black, red and spanish. First class white oak ties bring 70c. on the railroad; second class white oak 50c.; first class mixed oaks and chestnut bring about 40c. No reliable figures could be obtained for the tie production for 1907, but it is estimated at 15,000, of which 7,000 were No. 1 white oak and the balance No. 2’s, mixed oaks, and chestnut. POLES. The only species cut to any extent for telephone and telegraph poles is the chestnut, and the available supply of that timber is about exhausted. Poles 8” in diameter at the top end and 35 feet long bring about $5 each along the right of way of pole lines under con- struction. Poles 20 to 25 feet long for local telephone lines bring about $2.00 to $3.50 each delivered. PILES. Heretofore few piles have been shipped from the county, but under the present demand shipments are likely to increase. Oak is used almost exclusively, but only a small part is white oak, which is in greater demand for other purposes. Pin oak is the favorite oak for piling, since it meets the requirements of length and free- dom from short crooks better than any other. The current prices for mixed oaks, f. 0. b. cars, are as follows: UBT Ue Ie ta conte carte Ae Papas Se cyan Sis 9 cents per linear foot. 6027 OL TECE see issih ee sisi to 11 cents per linear foot. WO: Feet and’ Overs. cece es Ae eee 12 cents per linear fcot. MARYLAND GEOLOGICAL SURVEY 239 The specifications call for a diameter of 6” at the top end and one of 14” inside bark at 2 feet from the butt end. FENCING MATERIAL. Chestnut, red cedar and locust supply nearly all of the fencing material used in the county. With the growing scarcity of chestnut poles for rails, wire is coming into more general use. Large quan- tities of cedar, locust and chestnut posts are used every year on the farms and a small quantity, mostly red cedar, was shipped out dur- ing the past year. EXPORT WOODS. For many years timber buyers have been buying choice trees of the valuable species for the foreign export trade. The very best specimens of large walnut, poplar, hickory, white oak and ash go into this trade, which amounts to a considerable item. The prices (f. o. b.) at Baltimore, with dimensions required, are given below. All logs are measured in the round by Doyle’s Log Rule: Black Walnut.—F$35 to $100 per 1,000 feet, B. M. in lengths of 10 feet and up, and of a minimum diameter of 14 inches. Same to be hewed on four sides to show a little black wood. Hickory.—$35 per M. in lengths 10 feet and up, and 10 inches and over in diameter. Same shipped with bark on. Poplar.—$27 per M. in lengths 12 feet and up, and 24 inches and up in diameter. Same hewed on four sides. Oak.—$25 per M. in lengths 12 feet and longer, and 24 inches and up in diameter. Round, with bark on. Ash.—$25 per M. in lengths 10 feet and longer, and 10 inches and up in diameter. Round, with bark on. An estimate of the total annual wood and timber cut of the county, based on the most reliable data obtainable, indicates an equivalent of 20,000,000 board feet if firewood be included. TRANSPORTATION FACILITIES. Since wood is a bulky product, its market price is determined, in a large measure, by its accessibility to shipping points and the freight charges to the markets. The county has exceptionally good 240 THE FORESTS OF PRINCE GEORGE'S COUNTY transportation facilities and good nearby markets. ‘There are two trunk lines of railroad, and three shorter lines traversing the county, in addition to two electric lines. It has also good water transporta- tion on the southwestern and southeastern boundaries, thus bring- ing all sections within easy reach of the markets. There are several good wagon roads and others will be greatly improved under the new system of State roads. Most of the roads, however, are poor in the winter season when much of the wood and timber hauling is done. Freight rates by rail from Upper Marlboro, the county seat, to Baltimore are 80c. per ton by the carload for both cordwood and lumber. This is equivalent to about $1.20 per cord for pine, $1.60 per cord for oak, and for oak lumber about $2.20 per thousand feet B. M. The rates to Washington are about the same. DrstTRUCTIVE INFLUENCES. The main causes responsible for the present poor condition of the forests are fires, browsing of animals and destructive methods of cutting. FIRES. Forest fires in the county for the year 1907 burned over 900 acres of woodland and caused an estimated loss of $3,600 in fences and timber burned. The loss resulting in the decreased producing power of the forest is not included; with this added the amount would be many times greater than reported. During the previous year the estimated loss was five times as great. The fire damage has been ereatest over the northern and western sections of the county, where it alone has, during the past twenty years, cut down the producing capacity of the forests at least one-third. The effects of fire are: (a) the burning of the leaves and litter on the ground which are needed to conserve the moisture, protect the seed, and to fertilize the soil; (b) the destruction of the seed, and young seedlings that have already started, and which are so essential for the renewal of the forest; (c) the burning of the cambium, or living wood of young trees, on the side most exposed to the fire, caus- MARYLAND GEOLOGICAL SURVEY QA ing the bark to peel off, thus exposing the wood to decay. The tree becomes stunted, decay enters the wood and gradually works its way up into the trunk, rendering the tree practically worthless; (d) a severe fire in the brush, left by logging operations, often kills all the trees that remain, entailing a total loss of growing stock. Cause of fires—The principal causes of fire are railroad locomo- tives, careless burning of brush, hunters, and careless smokers. Nearly all fires could be prevented with reasonable care. Under the State Forest Laws,’ any individual or corporation maliciously, or carelessly, causing a fire that injures another’s lands is hable to fine or imprisonment, or both. Since this law was enacted in 1906 forest fires have been much less frequent. By cooperating with the State Forest Wardens in suppressing fires and in bringing offenders against the law to account, the fire-damage may be greatly reduced. Preventive Measures——Where there are small woodlots, sur- rounded by cultivated land, the danger from fire is slight, but in the case of larger tracts, especially where they are traversed by or border upon public highways, or railroads, there is considerable danger. Most fires occur during two seasons of the year, either in the late autumn after the leaves fall, or in the early spring shortly before the new leaves appear. The best preventive measures are to keep the dead brush cleared up, particularly along the sides of the wagon ‘roads, or railroads. Where a railroad traverses the woods, or passes along the edge of it, a fire line may be cleared along the sides of the track wide enough to catch all sparks and hot cinders that are thrown out by the locomotives. This line may be easily and cheaply con- structed by burning the leaves and litter, rather than to attempt to rake the space clear of inflammable material. Wagon roads and wide paths through the woods often serve as effective barriers to the spread of fire if they are kept clear of leaves and dry brush. GRAZING. It is a common practice throughout the county to inclose the wood- lot with a fence, and to use it for pasture. This is a bad policy for 1A copy may be had on application to the State Forester, Baltimore, Md. QA42 THE FORESTS OF PRINCE GEORGES COUNTY the reason that if the wood is thick enough (fully stocked) there will not be sufficient light for grass to grow, hence little feed for cattle. On the other hand if the wood is open enough to permit grass to grow, it is usually because the young trees have been killed out by the browsing of cattle, hence poorly stocked and producing little growth. If the wood is to be thickened up by young growth to produce a full yield, cattle must be excluded to give the seedlings a chance to start. In other words, it is out of the question to expect the woodlot to furnish pasturage and at the same time grow a full crop of timber. The killing of young growth is not the only damage. DESTRUCTIVE METHODS OF CUTTING. Owing to the former low prices of standing timber it was not profit- able to cut any but the best trees and hence, for 50 years or more, there has been a repeated culling of the forest. At first the best of the walnut, cherry, and poplar that was most accessible was cut, then, as timber prices advanced, and logging appliances were improved, new areas were invaded and the best of the white oak was gotten out. Later the same tracts were given over to logging opera- tions in which all good timber was cut out by portable mills. With the advent of tie cutters and buyers of telephone and telegraph poles even the smaller oaks and chestnuts have been culled from most of the stands. With the constant cutting of the valuable species the forest has largely changed from one in which the desirable kinds of trees formed the principal stand to one in which such trees have been supplanted largely by inferior ones. In other words the cut- ting was for immediate returns and little or no attempt was made to suppress the undesirable species and to encourage the desirable ones in the future growth. Cheap timber led to extravagant waste, so that after logging operations were over, the ground was strewn with big tree tops and brush so that the fires, which usually followed such operations, were so intense as to complete the destruction of the stand. Oo MARYLAND GEOLOGICAL SURVEY 24 Forrest MANAGEMENT. The need of more conservative management for the woodlands of the county is emphasized by a statement of the following facts: 1. The present woodland area is not producing one half the rev- enue, as regards quantity and quality of produce, that it is capable of doing under judicious management. 2. A good market is certain for forest produce of nearly all kinds. Prices have nearly doubled in the past ten years. 3. The climatic and soil conditions are favorable for the growth of timber. When the forest is properly protected the natural growth is rapid. 4. The species native in the county, and already established in the forest, are mostly of the valuable kinds. Proper management will insure a greater representation of such species in the present stand and therefore greatly increase the final returns. 5. There are many small areas, either growing up to worthless brush, or exhausted farm land where agricultural crops bring but small returns, which would bring profitable returns if planted to forest trees. Valuable species for the purpose are chestnut, red oak, pin oak, yellow poplar and locust. The object of forest management is to secure on a given area the highest forest returns in the shortest time at the least expense. The plan of procedure will differ with the type of forest to be managed and its present condition. Under past abuse, due largely to eco- nomic conditions rather than careless methods, the forests have been reduced to a much depleted condition. ‘To restore them to a high state of productiveness, which is the business of forestry, will require careful, systematic treatment. In applying forest management the two main types—mixed hardwoods and pure pine—will require very different treatment. MIXED HARDWOODs. In mixed hardwood stands, where the forest contains a oreat variety of tree species differing in relative value, the main object should be to weed out the undesirable kinds, and to encourage the best trees of the merchantable species. In the case of the farmer’s 244 THE FORESTS OF PRINCE GEORGES COUNTY woodlot, where a relatively small area is required to produce a con- tinuous supply of fuel, fencing and building material, the selection system of management is the most practical. Under this method the farmer ‘‘selects” and removes, from time to time, such trees as he may require for immediate needs. The success of the system will depend upon the selection of the trees for cutting and the measures taken to secure a good reproduction of desirable species. The main principles involved are: (1) Cut trees as soon after they reach maturity, or as soon thereafter as they can be used to advantage, in order to give needed room for young growth that is required to restore the forest. (2) When cutting for fire wood, stakes, ete., cut out the dead wood, the crooked and undesirable trees, to give every advantage to the young, thrifty trees of the desirable species that are intended for the permanent stand. (3) Be careful not to create large openings where no reproduction has started. Where there is a fully stocked young stand to work with, it is usually not a difficult matter to mould it into a forest of excellent form. Whenever the trees of the desirable species are being too severely crowded by inferior ones, the latter should be cut out. This combined thinning and improvement cutting should be repeated every few years until the stand attains its height growth, when the trees left will be allowed to remain until maturity. Where the forest has been abused by excessive and injudicious cutting, and perhaps injured repeatedly by fire, the first considera- tion should be to get the stand as fully stocked as possible. This may often be accomplished by natural seeding, if the woodland is protected from fire; and cattle, sheep and hogs are excluded. Where the present stand consists of only scattering trees of undesirable species, and where there is not a sufficient number of seed trees of the desirable kind to seed the land, it will probably be the best plan to cut the woods clean and plant with the kinds of trees it is desired to grow. In the case of a woodlot where clear cutting of the whole area would entirely cut the supply of wood for the farm, the area may be cut off a few acres at a time, the operations extending over a number of years, so as to have a rotation of timber crops. MARYLAND GEOLOGICAL SURVEY 945 PURE PINE STANDS. The best system of management for pine land is to cut clean. Where the land is to be devoted to another crop of pine, it 1s gen- erally best to cut the pine off in strips along the east side of the woods. The strip should not exceed 150 feet in width. After the first strip is eut, 2 or 3 years should elapse before the next one is eut, so as to allow ample time for the recently cut-over strip to be fully seeded from the standing trees on the windward side. By cut- ting succeeding strips, and giving sufficient time for each to become seeded from the adjoining woods, a new stand will be established after each cutting without expense. Where fields have grown up in dense young pine stands, and where small sized firewood can be used, it will often pay to cut out the dead trees and those that are being killed out slowly by larger overtopping trees. This will insure a more rapid growth and a better development of the trees in the stand. Since there is so little market for small wood, it will generally not be advisable to thin the stand, since it is likely to cost more than is warranted by the slight increase in final returns. The market prices for cordwood and pulpwood are good, and will undoubtedly advance as more accessible supplies become exhausted. Even with present prices there is much of the sandy land now being cultivated with small profit, that would yield better returns if allowed to grow up in pine. A thick stand of pine at 20 years of age will cut nearly 20 cords per acre, and will increase in growth about 1 cord per acre each year up to 35 years, when maturity is reached. With cordwood stumpage at 60c. per cord, the gross return will be $12 per acre at the end of 20 years, or $18 at the end of 30 years. INDEX A Abbe, Cleveland, Jr., 64, 66. Agricultural conditions, discussed, 178. Alexander, John H., 26. Alexander, Wm. H., 17, 185. Anacostia river, 215. Analyses of Cecil Mica Loam, 177. of Collington Sandy Loam, 157. of Elkton Clay, 176. of Leonardtown Loam, 165. of Norfolk Loam, 171. of Norfolk Sand, 158. of Sassafras Loam, 168. of Sassafras Sandy Loam, 169. of Susquehanna Loam, 174. of Susquehanna Clay Loam, 175. of Westphalia Sand, 160. of Windsor Sand, 163. Aquia formation, 100. areal distribution of, 101. character of materials of, 101. paleontologie character of, 102. strike, dip and thickness of, 102. stratigraphic relations of, 102. subdivisions of, 102. Areal distribution of Aquia formation, 101. of Arundel formation, S87. of Calvert formation, 106. of Choptank formation, 110. of Lafayette formation, 112. of Magothy formation, 94. of Matawan formation, 97. of Monmouth formation, 99. of Nanjemoy formation, 103. of Patapsco formation, 90. of Patuxent formation, 86. of Raritan formation, 91, of Sunderland formation, 118. of Talbot formation, 124. of Wicomico formation, 121. Artesian wells, 147. Arundel formation, 87. areal distribution of, 87. character of materials of, 8S. paleontologie character of, 89. strike, dip and thickness of, $9. stratigraphic relations of, 89. B Bags. R.M:, Jr, 6s. Bailey, J. W., 44. Bauer: je As, US) ila. Berry, BH. W., 7, 68. Besley, F. W., 18. Bibbins, A., 7, 60, 67, 68. Bladensburg, precipitation at, 195. temperatures at, 1938. Bonsteel, Jay A., 17, 151. Brooke, Richard, 204. Bryan, O. N., 54. Bowie, magnetic station at, 217. Building-stone, discussed, 140. Cc Calvert formation, 106. areal distribution of, 106. character of materials of, 106. paleontologic character of, 107. stratigraphie relations of, 108. strike, dip and thickness of, 107. sub-divisions of, 108. Cecil Mica Loam, 175. mechanical analyses of, 177. Character of materials of Aquia forma- tion, 101. of Arundel formation, 88. of Calvert formation, 106. ot Choptank formation, 110. of Lafayette formation, 113. of Magothy formation, 94. of Matawan formation, 97. of Monmouth formation, 99. of Nanjemoy formation, 104. of Patapsco formation, 90. of Patuxent formation, 86. of Raritan formation, 92. of Sunderland formation, 119. of Talbot formation, 124. of Wicomico formation, 122. Cheltenham, temperatures at, 193, 194. precipitation at, 194. magnetic staticn at, 216. Chesapeake Group, 106. origin of materials of, 80. Chestnut, 235. Choptank formation, 110. areal distribution of, 110. character of materials of, 110. paleontologic character of, LEO: stratigraphic relations of, 111. strike, dip and thickness of, 111. sub-divisions of, 112. Claggett, Wm. B., 5. Clark, Wm. Bullock, 7, 9, 27, 52, fa) 56. Due GO, Gla G2aGom G4, (Go. 67, 68. 245 Clays, discussed, 1387. Climate, discussed, 185. College Park, precipitation at, 196. temperatures at, 195. Collington Sandy Loam, 152. chemical analyses of, 155. mechanical analyses of, 157. Columbia Group, 116. Conrad; TL A, 31;°36, 37, 38, 40: 41, 42, 45, 46. Contents, 11. Cordwood, 237. Cretaceous clays, 138. Crothers, Austin L., 5, 9. Crystalline rocks, discussed, 84. sedimentary record of, 127. waters of, 147. Cultural treatment of forests, 243. D Dally Wee Hi to7, 66: Dartons Noe, 56.58), 59) «625, 60. Desor, E., 43. Diatomaceous earth, discussed, 142. Ducatels I. ul 6s 9, 40.041. Dug wells, discussed, 146. |= Elkton clay, 174. mechanical analyses of, 176. Eocene, discussed, 100. sedimentary record of, 151. Eocene water-horizon, 150. Estuaries, 76. Export woods, 239. = Fairhaven diatomaceous earth, 108, Fence timber, 239. Finch, John, 35, 36. Nisher, R. S., 43. Fcentaine, W. M., 54, 67. Forests, discussed, 219. use of, 256. Forest fires, 240. Forest management, 245. Forest types, 221. Forest trees, 235. Fort Foote, precipitation at, 197. temperatures at, 197. Fort Washington, precipitation at, 198. temperatures at, 198. G Gabbro, discussed, 85. Geological Record, interpretation of, 127. INDEX. Geological Survey Commission, 5. Geology, discussed, 83. Glauccnite marls, 141. Granite-Gneiss, discussed, 84, Gravels, discussed, 140. Grazing, 241. H Harlan, R., 37. Harris, -G. D2, 59: Hayden, H. H., 35. Heilprin, Angelo, 48, 49. Hickory, 236. Higgins, James, 43, 46. Historical Review, 24. Hydrography, discussed, 207. Illustrations, List of, 15. Infusorial earth, 142. Interpretation of Geologic record, 127. Introduction, 21. Iron ore, discussed, 142. K Keith, A., 65. Keyser, W., 58. L Lafayette formation, 112. age of, 112. areal distribution of, 112. character of materials of, 115. paleontologie character of, 115. physiographic expression of, 114. sedimentary record of, 98. stratigraphic relations of, 115. thickness of, 115. Lafayette plain, 73. Lafayette stage, 79. Laurel, precipitation at, 200. Patuxent river at. 208. temperatures at, 199. Leidy, Jos., 46. Leonardtown Loam, 164. mechanica] analyses of, 165. Leonardtown gravelly loam, 166. Lower Cretaceous, discussed, 85. sedimentary record of, 128. water in, 148. M Maclure, William, 26, 34. Magnetic declination, discussed, 215. Magothy formation, 95. areal distribution of, 94. eae - . i i i i i ee i > “lag ~4 Ax eee ae < I 4 =i 9 A a = a he A