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“ducation Department Bulletin” ts 


Published fortnightly by the University of the State of New York 


Entered as second-class matter June 24, 1908, at the Post Office at Albany, N. Y., 
under the act of July 16, 1894 


-No. 492’ ; ALB AUN YaCN Sv APRIL I, IQII 


New York State Museum 


Join M. CLarKE, Director 


Museum Bulletin 148 


GEOLOGY OF THE POUGHKEEPSIE QUADRANGLE 


BY 
B U OF 
AMERIC THNOLOGCY, 


{911 


FSi 


C. E. GORDON 


PAGE PAGE 
WMGATICHON OS... sce cl ete eee 5 | The Wappinger creek belt....... 48 
Location and other general features | The Fishkill limestone........... 70 

of the quadrangle.........4..4. 6 | The “Hudson River” slate group 82 
pee Rees ey i Preglacial history of the drainage 96 
ae RR eT cee: Gizemlt ecology Wy. 2 ae beet GOR ae 

EES Seen “+ 9] Retreat of the ice sheet.......... 100 
Stratigraphical table....... eee tr | Postglacial erosion.............. 104 
The Precambric gneisses......... tr | Lhe present depression.......... 105 
SeREauoniGui. basic eruptive Other drainage features and adjust- 

and associated metamorphic ‘7 ae SE SBS mie OE SB rc actcre - : 
ig ee Seas A NT aay Ca ea Bi AADC: LOTS Fh ol erate no yele ii ate:*! > 
The basal quartzite (Poughquag) 39 Economic geology Bi Gp Serre Cs aren 106 
The Wappinger (Barnegate) lime- EA ESOS ray: AF. Pics? sea ee ele Soe 110 
Sii@itey Bhs a0 Sa: Het BO ae ene oe eitsy Wil Lis (6/S> AE Re ge AR NB nee 117 


114348 
ALBANY 
UNIVERSITY OF THE STATE OF NEW YORK 


IQI1 
M248r-N 10-1500 


STATE OF NEW YORK 
EDUCATION DEPARTMENT 


Regents of the University 


With years when terms expire . 


1913 Wuiretaw Rei M.A. LL.D. D.C.L. Chancellor New York. 
1917 St Crain McKet.way M.A. LL.D. Vice Chancellor Brooklyn 


1919 Danie, Beacw Ph.D. LL.D. - - - — — Watkins 
1914 Puiny T. SExToN LL.B. LL.D. — - - -— -— Palmyra 
1912 T. GuitForD SmitH M.A. C.E. LL.D. - - = Buffalo 
1915 ALBERT VANDER VEER M.D. M.A. Ph.D. LL.D. Albany 
1922 CHESTER S. Lorp M.A. LL.D. - - -— —- —- New York 
1918 Wiit1am Nottincuam M.A. Ph.D. LL.D. - - Syracuse 
1920 Eucene A, Puitpin LL.B. LL.D. - = = = New York 
1916 Lucian L. SHEDDEN LL.B. LL.D. - - - — Plattsburg 
1921 Francis M. CARPENTER - —- — -— — — -— Mount Kisco 
1923 ABRAM I.’ Erkus LL.B. = -=- = -— = = New Wonk 


Commissioner of Education 


ANDREW S. DRAPER LL.B. LL.D. 


Assistant Commissioners 
Avucustus S. Downine M.A. Pd.D. LL.D. First Assistant 
CuHarves F. WHEELOCK B.S. LL.D. Second Assistant 
Tuomas E. Frnecan M.A. Pd.D. Third Assistant 


Director of State Library of 


JAMES I. WYER, Jr, M.L.S. 


Director of Science and State Museum 


Joun M. Crarke Ph.D. D.Sc. LL.D. 


Chiefs of Divisions 

Administration, GEorGE M. Witzy M.A. 
Attendance, James D. SULLIVAN 

Educational Extension, WILLIAM R. Eastman M.A M.LS. 
Examinations, HarLAN H. Horner B.A. 
. Inspections, Frank H. Woop M.A. 

Law, FRANK B. GILBERT B.A. 

School Libraries, CoarLes E. Fitcu L.H.D. 
Statistics, Hiram C. CasE 

Visual Instruction, ALFRED W. AsRAmMs Ph.B, 
Vocational Schools, ARTHUR D. Dean B.S. 


New York State Education Department 


Science Division, November 5, 1910 


Hon. Andrew S. Draper LL.D. 
Commissioner of Education 

Dear sir: I beg to transmit to you herewith a manuscript en- 
titled The Geology of the Poughkeepsie Quadrangle, accompanied 
by a geological map which has been prepared under my direction 
by Professor Clarence E. Gordon. The work has been executed 
with circumspection and accuracy and I recommend the publication 
of the matter transmitted, in the form of a bulletin of this Division. 

Respectfully 
JouHN M. CLARKE 


Director 
STATE OF NEW YORK 


EDUCATION DEPARTMENT 


COMMISSIONER'S ROOM 


Approved for publication this 7th day of November 1910 


Commissioner of Education 


Education Department Bulletin 


Published fortnightly by the University of the State of New York 


Entered as second-class matter June 24, 1008, at the Post Office at Albany, N. Y., under the 
act of July 16, 1894 


No. 492 ALBANY, N. Y. APRIL 1, 1911 


New York State Museum 


Joun M. Crarxe, Director 
Museum Bulletin 148 


GEOLOGY OF THE POUGHKEEPSIE QUADRANGLE 


BY 


CLARENCE E. GORDON 


INTRODUCTION 


The preparation of this paper was begun at the suggestion of 
Professor J. F. Kemp. The field work was carried on at intervals 
during the summers of 1906-7-8-9. During the intervening win- 
ters the extensive literature dealing with the geology of eastern 
New York State, western New England and the areas of similar 
rocks at the south was read with care. 

A preliminary map of the quadrangle was prepared by a sum- — 
mer school party of Columbia University at work for a week under 
the direction of Professor Kemp, Professor A. W. Grabau and Dr 
C. P. Berkey. This was of great assistance in the field. € 

The writer owes much to Professor Kemp for kindly criticism. 
Dr Charles P. Berkey has offered important suggestions. Par- 
ticular thanks are due Professor John M. Clarke for a generous 
interest which has made some of the field work easier of execution. 


6 NEW YORK STATE MUSEUM 


LOCATION AND OTHER GENERAL FEATURES OF 
THE QUADRANGLE 


The Poughkeepsie quadrangle lies in the Hudson river valley 
about midway between New York city and Albany. It falls 
between parallels 41° 30’ and 41° 45’ north latitude and meridians 
73° 45’ and 74° oo’ east longtitude, and is therefore 17.5 miles 
long by about 13.2 miles wide. It embraces an area of about 230 
square miles. The Hudson river crosses the quadrangle from 
north to south near the western boundary. ‘The river is slightly 
deflected to the west at New Hamburg and forms the quadrangle 
boundary at the southwest corner. 

The larger portion of the area lies east of the Hudson in the 
southwestern part of Dutchess county. At the very southeast 
corner is a triangular bit of the township of Kent in Putnam 
county. West of the river is a strip of Ulster county and a block 
from the northeastern portion of Orange county. * 

Poughkeepsie, the county seat, is a city of about 25,000 inhabit- 
ants. Wappinger Falls on Wappinger creek, Matteawan on Fish- 
kill creek and Fishkill Landing on the Hudson, opposite New- 
burgh, are important villages. Wappinger Falls and Matteawan 
are manufacturing towns and each owes its size and importance 
to the stream on which it -is located. East of the Hudson the 
region is chiefly a farming country and is well adapted to tillage, 
grazing and fruit growing. West of the river the topography, 
soil and drainage are peculiarly adapted to the growing of fruit, 
for which the proximity of the river affords excellent climatic 
conditions. 

Dutchess county was settled very early in the history of the 
State. The country is attractive. It is easy to imagine that im- 
migrants voyaging up the Hudson through the inhospitable region 
of the Highlands would have been attracted by the stretches of 
open eountry which lay north of the rugged mountains. 

The quadrangle is easy of access. Boats plying between New 
York and Albany stop at Newburgh and Poughkeepsie. The New 
York Central and West Shore lines, connecting with Albany and 
the West, follow the banks of the Hudson. The former joins with 
the Newburgh, Dutchess and Connecticut division of the Central 
New England at Dutchess Junction and Fishkill Landing, and at 
Poughkeepsie with the main line division of that road. At Pough- 
keepsie it also crosses the Highland division of the New York, 


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Fig. 1 Sketch map ee location of Poughkeepsie quadrangle 


GEOLOGY O& THE POUGHKEEPSIE QUADRANGLE 7 


New Haven and Hartford. Ferries cross between Fishkill Land- 
ing and Newburgh and between Poughkeepsie and Highland on the 
West Shore Railroad. 


MORO GRE TIN 


East of the Hudson the topography is chiefly that of a rolling 
upland of moderate elevation, which is due in part to the nature 
and structure of the underlying rock formations as affected by 
erosion, and in part to the mantle of glacial deposits. 

Along the southern margin of the quadrangle are several rugged 
spurs of the Highlands. These are bold, often precipitous, and 
usually wooded. They are known as the Fishkill mountains, receiv- 
ing their name from old Fishkill township, of which they are a part. 
These mountains are made up chiefly of Precambric gneisses and 
are flanked by and faulted with the Paleozoics of the valley. 

The westernmost Highland spur is the northern extension of 
Breakneck mountain ridge and the part within this quadrangle is 
known as Bald hill (see plate 1). It has a maximum elevation of 
1540 feet. The Mount Honness spur next east has an elevation 
of 840 feet at its northern extremity, Mount Honness proper, but 
reaches a height of 1300 feet near the quadrangle boundary (see 
plate 2). A short spur east of Honness, with an elevation of 
885 feet, separates it from Shenandoah mountain, which has a 
maximum height of 1115 feet. East of Shenandoah mountain the 
Highland mass attains an elevation of 1232 feet at “ Looking Rock,” 
which is at the summit of the steep northwestern slope. This 
spot is widely known because of its fine view. 

North of the Fishkill mountains the rocks within the quadrangle 
are principally shales, slates, grits, phyllites and limestones. The 
more metamorphic character of these strata as they are followed 
eastward from the Hudson finds expression in the higher elevation 
of the slate and graywacke in the northeastern part of the area. 
Here the hills in places reach a height between 700 and 800 feet. 
West of the Hudson the average elevation in the slates and grits is 
greater than on the east of the river, often attaining 400 to 600 
feet. “Illinois mountain,” the northern extremity of Marlbor- 
ough mountain, is 1105 feet high. 

In contrast to the heights is the gorge of the Hudson, which 
borings have shown reaches a depth near Storm King of over 
Feo feet. 


8 NEW YORK STATE MUSEUM 


DRAINAGE 


The Hudson river is the dominating factor in the drainage of | 
this area. The principal tributaries of the master river within 
this quadrangle come in from the east. The most important are 
Wappinger and Fishkill creeks; of lesser importance are Casper 
and Fallkill creeks. 

Wappinger creek has its source near Pine Plains, some 16 or 17 
miles northeast of Pleasant Valley, on the southwest of a narrow 
divide that separates its headwaters from the valley of Shekomeko 
creek. It has a general southwest course along a narrow limestone 
belt, and finally enters the Hudson at New Hamburg. At present it 
bears away somewhat from the limestone along its lower reaches 
and flows across the slates, over which it cascades gently in several 
places. At Wappinger Falls it makes a descent of about 60 feet 
over the slates, and from this village to the Hudson, a distance of 
about two miles, it occupies a drowned valley. It receives a few 
small tributaries within the quadrangle, the largest of which drains 
the slates southeast of Wappinger Falls and empties into the main 
stream below the village. 

Wappinger. creek furnishes power at Pleasant Valley, near Titus- 
ville, and at Wappinger Falls, and formerly was utilized at 
Rochdale. 

Fishkill creek is a somewhat larger stream and has a greater 
watershed. It also drains a large part of the area just to the east, 
where the main stream has its source on the western slope of 
Chestnut ridge, a high mass of schist separating the Clove and 
Dover-Pawling valleys. East of the quadrangle it receives an ~ 
important tributary with its source in Whaley pond. Sylvan lake 
sends a small tributary into this stream near the eastern edge of 
the quadrangle. 

Several good-sized brooks join the main stream from the north. 
Of these Whortlekill creek is a small brook which enters the quad- 
rangle just east of Arthursburg, about a mile from its source. It 
joins the Fishkill about a mile south of Hopewell Junction. Jack- 
son and Sprout creeks are larger. The former drains the western 
slope of the ridge between Lagrangeville and the Clove valley, 
while the headwaters of Sprout creek extend to the narrow ridge 
northeast of Verbank, whose eastern slopes drain into the Dover- 
Pawling valley. Sprout and Jackson creeks join north of Fishkill 
Plains and the stream formed by their union flows into. Fishkill 
creek, two miles north of Brinckerhoff. 


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GEOLOGY OF THE POUGHKEEPSIE QUADRANGLE 9 


Several brooks which drain the northern slopes of the Fishkill 
mountains and the valleys between them join Fishkill creek from 
the south. Of these, the largest are those leaving the Highlands 
through Shenandoah hollow and the valley of East Fishkill Hook, 
and “Clove creek” south of Fishkill Village. Fishkill creek fur- 
nishes power at Hopewell, Brinckerhoff and Matteawan. 

Casper creek rises near the northern boundary and flows south- 
west in a rather wide valley to the Hudson which it joins two and 
one-half miles north of New Hamburg. 

Fallkill creek drains a large area to the north. It flows in a 
general southwest course to Poughkeepsie where it turns on itself, 
and, making a large loop, flows north for one-half of a mile and 
then west to join the Hudson. 

Several brooks, but none of any size, drain the slopes on the west 
of the Hudson. 

There are no natural lakes or ponds of conspicuous size within 
the quadrangle. Those of any consequence apparently date from 
the time of the retreat of the ice sheet from this region. 


GENERAL GEOLOGY 


The Fishkill mountains belong to the Highlands province of Pre- 
cambric rocks. These have their greatest development in Putnam 
county just to the’ south. The spurs that have been mentioned 
‘are the northern terminations of ridges of gneisses which have a 
general northeast-southwest trend. Above Peekskill these gneisses 
are continued across the Hudson into New Jersey. Eastward they 
extend into Connecticut. 

The summits of the Fishkill mountains, with those of neighbor- 
ing ones at the south, present a fairly even sky line which may be 
followed northeastward along the crests of the ridges of the younger 
rocks. This general uniformity of level is believed by many to 
mark a former peneplain in this region toward the close of Cretacic 
time (see plate 3). 

North of the Fishkill mountains are the younger rocks of the area. 
In general, these do not now tend to climb far up the flanks of the 
older masses. In most cases the two are faulted against each other 
and the rocks of the mountains reach close to their bases. In a few 
places the younger strata extend up a moderate distance on the older 
rocks and are disturbed relatively little. 

These younger strata rest unconformably upon the Precambric. 
They are the southwestward representatives of the rocks of western 
Massachusetts and Vermont and are now known to include strata 


1K@) NEW YORK STATE MUSEUM 


which range in time from the base of the Paleozoic to the upper part 
of the Ordovicic period. Northeastward these rocks extend into 
Massachusetts and Vermont and southwestward into New Jersey, 
Pennsylvania and beyond. 

Within the quadrangle they are of considerably lower average — 
elevation than the gneisses of the mountains. This reduced eleva- 
tion is believed to represent the erosion that has taken place in 
these rocks below the Cretacic level after the peneplain had been 
elevated at the close of Cretacic time. 

So far as now known, these younger strata have no later rocks 
older than the Quaternary overlying them within the limits of the 
quadrangle. 


PREVIOUS GEOLOGIC WORK 


Because of the extensive geographic development of these rocks 
and their difficult geology there has appeared, during the last fifty 
years or more, a large body of literature dealing with them through- 
out their length and breadth. The work has been carried on under 
the auspices of State and federal surveys and by private enterprise. 
Work within this quadrangle was undertaken early in the history 
of serious geological investigation in this country. 

In 1843 W. W. Mather submitted his quarto report on the Geology 
of the First District of the State of New ‘York UhisWdealk 
with southeastern New York and was the first important contribu- q 
tion bearing on the geology of this area. With the exception, per- 
haps, of an excursion by Sir William Logan and James Hall in 1864, 
which resulted in the assignment of the younger rocks of this and 
neighboring areas to Logan’s Quebec Group, and which introduced 
much confusion at the time, no other important contribution was 
made until 1878. 
' In that year T. Nelson Dale discovered fossils in the slates at 
Poughkeepsie. The fossils were assigned by Hall to the “ Hudson 
River Group.’ ‘The find attracted the attention of Professor J. D. 
Dana to the strata of southern Dutchess county. This eminent 
geologist, what the time was working at the difficult stratigraphy 
of western Massachusetts and the neighboring portion of New 
York State, now traced the limestones from the north to the Hud- 
son river, discovered fossils in them at Pleasant Valley, and dis- 
cussed their general geologic significance. 

Apparently through the influence and encouragement of Dana, 
_ Professor W. B. Dwight began his fruitful investigations in the 
Wappinger limestones of Dutchess county. Professor Dwight’s 
papers were published at intervals from 1879 to 1900. His investi- 


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GEOLOGY OF THE POUGHKEEPSIE QUADRANGLE If 


gations greatly extended our knowledge regarding the age of the 
Wappinger limestones, particularly those of the Wappinger creek 
belt. 

In 1886 J. C. Smock, as a part of a preliminary report on the Pre- 
cambric rocks of the Highlands east of the Hudson, discussed the 
gneisses of the Fishkill mountains. But notwithstanding these con- 
tributions, the areal geology has not been mapped in detail up to 
the present time. 


_STRATIGRAPHICAL TABLE 


SEDIMENTARY 


PERIODS ERUPTIVES 
Formations Terranes 
Alluvium Recent 
Quaternary Terraces 
Kames Glacial 
Drumlins 
(Unconformity) 
“Hudson River’’ slates, 2 
grits and phyllites Utica? 
Trenton 
Ordovicic Wappinger limestones and| Trenton 
dolomites, in part (Disconformity) 
Beekmantown 
—__—$§$§_————| Hortontown hornblende 
(Disconformity ?) rock 
Cambric Wappinger limestones and| Potsdam 
dolomites, in part Slay 
Georgian 
Poughquag quartzite Georgian 
(Unconformity) 
5 Gneisses of the Fishkill : Shenandoah granite 
Precambric mountains and inliers of| ‘‘ Grenville ”’ Bald Hill granite gneiss 
these rocks 


TEE PRECAMBRIC GNEISSES 


DISTRIBUTION 

Within the Fishkill mountains the boundary of these rocks, as 
shown by the map, follows closely the lower contour lines of the 

spurs. 
_ The Glenham belt is an inlier of these rocks. It has the same 
trend as the ridges of the gneisses in the Highlands and extends as 
a harrow strip from a point just north of the carpet mill at Glenham 
northeastward to “ Vly mountain.”? 


1 The hill marked Fly mountain on the map is just southeast of what, 
in this vicinity, is called Vly mountain, corrupted to Fly mountain. The 
swamp just south of the eminence doubtless suggested the name (Vly- 
swamp). 


I2 NEW YORK STATE MUSEUM 


South of the Glenham belt, in the town of Matteawan, are two 
smaller inliers of the gneisses connecting the Glenham belt with — 
the Highlands. 

Between the rocks of the Highlands and those composing the 
masses of inliers there are some differences which help to throw 
light on the history of both. There are also marked resemblances 
which apparently serve to clinch their relationship. 


PROBLEM OF THE GNEISSES 


The study of the gneisses speedily develops very puzzling prob- 
lems, which in all cases may not admit of satisfactory solution. In 
some way these rocks must express the several successive changes 
which they have experienced. A complex history is suggested, but 
all its events are not easy to trace. 


PROMINENT STRUCTURAL FEATURES 


The most impressive feature of the gneisses is the northeast- 
southwest alignment of the ridges which constitute their outcrop. 
Between the ridges are parallel longitudinal valleys. From the 
published descriptions, these features, with some exceptions, seem 
to hold for the entire Highlands and to extend southward into West- 
chester county. 

The gneisses are uniformly banded or foliated throughout their 
entire breadth from west to east, and the strike of the foliations 
in general follows the trend of the ridges. In a few places only 
does the foliation approximate schistosity in any degree. 

Over most of the area there is an easily distinguishable arrange- 
ment in parallel stratalike masses which also follow the topo- 
graphic features. These do not show an orderly repetition, though 
masses of very similar mineralogy are irregularly repeated. Occa- 
sionally more massive types occur, but these, too, seem to follow the 
structural features just mentioned. The prevailing dip of the folia- 
tion planes to the southeast imparts a strongly isoclinal character. 

The ridges clearly date from Postcambric time. It seems rea- 
sonable to infer that the other structural features just outlined 
have a common origin and belong to an earlier epoch. 

There is much evidence of extensive faulting which is developed 
chiefly, or at least most prominently, along the strike. Such faulting 
might easily account for the lack of orderly repetition of character- 
istic rock types. Most of this faulting belongs to the disturbance 


GEOLOGY OF THE POUGHKEEPSIE QUADRANGLE 13 


that produced the ridges. The gneisses clearly show the effects of 
repeated orogenic disturbances. 

In some places it is clear, from the position and structure of the 
overlying younger rocks, that most of the features of the gneisses 
date from Precambric time. Where the relationship of the basal 
quartzite to the underlying gneiss is most plainly seen, as in the West 
Fishkill Hook,’ the latter stands at a high angle with a uniformly 
northeast-southwest strike, while the quartzite dips at a low angle 
with varying strike. In other places the discordance between the 
dips and strikes is plainly discernible. The quartzite has been folded 
relatively little in many places, and never within this quadrangle to 
the extent shown by the gneisses. Faulting, instead of extreme 
folding, occurred in connection with Postcambric movements within 
the gneisses. 

The early crystalline condition of the gneisses would have favored 
faulting and shearing and would have prevented much later folding 
within them. It is certain that the isoclinal character is of Pre- 
cambric age. 

It seems possible, therefore, in a large way, to apportion the 
structural features of these gneisses as seen in the field among 
orogenic movements of Precambric and later time. It is quite 
uncertain how many different disturbances may have occurred in 
Precambric time and whether all the later structural features are 
of similar age. 

The lines of foliation, as seen in outcrops, are usually rectilinear. 
When wavy, they are only slightly so. This latter feature seemed 
most noticeable on Shenandoah mountain. Crinkling is rare. Two 
or three instances of it were noted in the Glenham belt. Jointing 
is common and frequently gives the appearance of thick exfoliation. 

Faults are divisible into two kinds, reversed and normal. It seems 
_most likely that the normal faults followed the compression that 
produced the thrusts and are therefore of the nature of adjust- 
ments. All the faults that have been noted appear to belong to the 
great mountain building process of Ordovicic time which elevated 
the Paleozoics of the Green mountain belt. This is indicated by the 
relations which exist between the younger and older rocks and by 
the fact that the fault lines of the mountains are projected north- 


1 The recesses east and west of the short spur that separates Mount 
Honness from Shetiandoah mountain are respectively known as_ East 
and West Fishkill Hook. 


I4 NEW YORK STATE MUSEUM 


ward into the younger strata, where they show features that leave 
their age unmistakable. 3 

Doubtless in some cases what now appear to be reversed faults of 
moderate displacement within the gneisses, or along contacts, are 
truncated thrusts of large size. This inference is borne out by the 
presence of large thrusts in the Paleozoics at the north. 

It would appear that not only did distinct normal fault breaks 
occur as the result of adjustments following the elevation of the 
Green mountains, but that normal slips occurred along the planes 
of the earlier thrusts. 

This feature is best shown in the relations now existing between 
Bald hill and the Mount Honness spur, and in similar ones between 
Shenandoah mountain and the mass of gneiss at the east of it. In 
these two instances the Paleozoics have clearly been dropped back 
between the gneiss spurs with a large throw on the west, marked 
in one case by the scarp on the east of Bald hill, and in the other by 
that on the east of Shenandoah mountain. 

The two spurs in each case tended to act as a single block. The 
normal fault intersects the thrust at an acute angle forming a tri- 
angular valley narrowing southward. Some backward movement 
along the thrust plane must have accompanied the slump. Dimin- 
ishing tension faulting eastward is marked by small scarps on the 
vest of the Honness spur but is not noticeable on the eastern gneiss 
mass. 

The Hook spur shows these features imperfectly developed. 


PETROGRAPHY 


General. The gneisses show much similarity in their mineralogy. 
Distinctive characters are furnished by the structure, the preponder- 
ance of some minerals, or the degree of alteration in the rock. A 
few composite types may thus be defined. It will be convenient 
to describe these first, while the variations in many instances may 
best be indicated in discussing their outcrops. The thin sections 
may be reviewed as a whole later. Possible ancient surface altera- 
tions must always be carried in mind. 

Bald hill granite gneiss. This rock is prominently developed 
within and south of the quadrangle. There is great uniformity in 
its general color, mineralogy and texture. It shows a few variations, 
but as a whole is remarkably homogeneous. In outcrops it is com- 
monly drab colored and granitelike in appearance. The thin sec- 


GEOLOGY OF THE POUGHKEEPSIE QUADRANGLE 15 


tion of the usual variety shows quartz in large and small anhedrons. 
Orthoclase and plagioclase are abundant, with the former slightly 
in excess. There is 
some microcline and 
hornblende is plentiful. 
Irregular grains of 
magnetite are frequent. 
There are a few scat- 
tered zircons. 

In some instances, 
even where the hand 
specimen appears rather 
massive, the thin seec- 
tion shows a stringer- 
like arrangement of the 
hornblende (see figure 
2) he smagnente 1s 
often hydrated, giving 


Fig. 2 Bald hill granite gneiss. Actual size 3 mm. Q, "a 
quartz; O, orthoclase; P, plagioclase; H, hornblende; surface EXPOSUTES a 


black, magnetite rusty color. 

The principal variation is a rock of coarser texture, with the 
mineralogy of a diorite. It shows hornblende, abundant plagioclase 
and a very little quartz (see figure 3). 

In one case where the 
rock was extremely 
fresh the magnetite 
formed a perfect pseu- 
domorph after the am- 
phibole and was abund- 
ant in the section, while 
the hornblende was 
greatly bleached. 

There is utter lack of 
evidence to show that 
the rock has undergone 
a complete change from 
an earlier condition. It 
would seem that, so far 


auc Tack! Was (UStibeeW Unis 4 Dickie vanation of the Bald Bill gneiss. Actual 
: : size 3mm. P, plagioclase; H, hornblende; Q, quartz 
discussed as to miner- 


alogy and texture, we are dealing with primary features. On the 


whole, the sections indicate a rock of plutonic habit which took on a 
gneissic character and underwent certain other changes at the time 


16 NEW YORK STATE MUSEUM 


of its formation. The gneissic character is best regarded as primary, © 
justifying the use of the term gneissoid granite to qualify the name 
granite gneiss. 

The restlessness of the magma at the time the minerals were 
forming seems to find expression in the stringerlike arrangement 
of the hornblendes and in parallelly arranged pellets of quartz occur- 
ring in the feldspars, which do not appear to be secondary and of 
later introduction. These features, with the rounded character and 
smaller size of some of the grains and the absence of micropegma- 
titic intergrowth, point to conditions hampering crystal formation. 

The thin sections also show certain dynamic effects of later date, 
in common with all the gneisses of these mountains, in the form of 
strain phenomena of different kinds. There are one or two instances 
of comparative freedom from such in which the quartz always gives 
sharp, decisive extinction and in which prominent cracks and bent 
lamellae are absent. 

Hornblende gneisses. The outcrops of these rocks are much 
alike and the thin sections which have been examined agree very 
closely. Exposures are dark in color. The essential minerals are 
chiefly plagioclase and hornblende, with some quartz and a little 
orthoclase. Magnetite is rather common as irregularly-shaped par- 

ticles, or as dustings. 

Zircons are occasional. 

Some sections show 

biotite in addition to 

hornblende, but the for- 
mer is decidedly subor- 
dinate and usually has 
every appearance of 
being secondary. It ap- 
parently belongs to that 
period of metamorph- 
ism which more usually 
‘ found expression in 

Strain phenomena of 

different kinds but 

which sometimes re- 


Uf 
7) 


ig. Sketch of a hornblende gneiss. Actual size 3 mm. : 3 
bee eee P, plagioclase; H, hornblende; black, mag- sulted in new minerals 


netite among the “ primary” 
ones, especially in those cases where the rock had previously been 
exposed to unusual alteration. The feldspars also frequently show 
evidence of former decay. The indurated and general compact 


GEOLOGY OF THE POUGHKEEPSIE QUADRANGLE 17 


condition indicates that the alteration is an ancient character. Fig- 
ute 4 gives a sketch of a thin section of typical hornblende gneiss. 


La 


f AAR 
* Qs 
5 SON 


Fig. 5 Sketch ofa micaceous gneiss. [| siz 
Q, quartz; O, orthoclase; P, plagioclase; B, biotite 


Actual size 3 mm. 


Micaceous gneisses. 
These may be passed 
Ovetm, biietlyw ay Except 
that biotite plays the 
role of hornblende, they 
are very similar in their 
mineralogy. In some 
cases magnetite is asso- 
ciated with a mineral 
whose identity is lost or 
obscured. The thin sec- 
tions often suggest that 
the prominent biotite is 
secondary and in these 
cases the outlines of an- 
other mineral, possibly 
hornblende, may be 
faintly traced. In these 


instances it is possible that the biotitic gneiss was first a hornblende 
rock and that it was subjected to more than usual alteration before 


recrystallization. 

Microcline is rather 
abundant.  Biotite oc- 
curs abundantly as a 
“primary ’’ mineral in- 
dependent of horn- 
blende. Sometimes 
these gneisses show 
much quartz and are 
finegrained, strongly 
suggesting altered sedi- 
ments. 

Shenandoah moun- 
tain granite. A coarse, 
white granite made up 
almost entirely of 
quartz and feldspar was 
noted on Shenandoah 


Fig. 6 Shenandoah mountain granite. Actual size 3 mm. 
Q, quartz; O. orthoclase; P, plagioclase; M, microcline; 


mountain at the summit of the steep northwestern slope, along the 


toad from the East Hook to Hortontown. 


It is very massive 19 


18 NEW YORK STATE MUSEUM 


appearance in the ledge and hand specimen. The thin section 
shows quartz, orthoclase, microcline and plagioclase. A few small 
and scattered flakes of muscovite, which is probably a primary min- 
eral, are present. Microcline is abundant. There is a tendency to 
microperthitic intergrowth of plagioclase and orthoclase. It has 
the earmarks of a plutonic rock and bears little evidence of 
eneissoid structure, so that if it is of Precambric age it must be 
thought of as having escaped any pronounced foliation. This seems 
remarkable, considering the prominence of foliation in the gneissic 
series. The effects of dynamic metamorphism are chiefly in the 
form of strain shadows in the quartzes. 

Glenham gneiss. The prevailing and characteristic surface rock 
of the Glenham belt is a granitic gneiss. It appears to be an altered 
derivative of other gneisses which are entirely similar to those of 
the Highlands, and which are exposed in places within the belt. 
The surface gneiss is 
foliated in certain por- 
tions, while in others it 
is massive. There are 
minor variations in tex- 
ture and in mineralogy 
which depend upon both 
an ancient and a more 
recent alteration. These 
varieties grade into one 
another. The gneiss is 
usually red from dis- 
seminated iron stains 
and over much of the 
belt is deeply chlorit- 
ized. 


Fig. 7 Glenham gneiss. Actual size 3 mm. QO, quartz; z 2, se 
M, microcline; P, plagioclase; CB, chlorite after biotite, The thin section 
Cea ee aay shows abundant quartz 


with orthoclase, microcline, plagioclase, and biotite altered to chlor- 
ite. Magnetite is abundant and zircons are occasional. 

Occasionally the rock consists of feldspar and quartz with very 
little or no mica. 


OUTCROP OF THE FISHKILL MOUNTAIN GNEISSES 


Matteawan. Gmneisses which can be readily traced into those of 
the Fishkill mountains outcrop. near their base in the eastern part 


- a = Ww 
a gg TS me 
eee ee rams, fF 
ee 


My 
ey 
5 
i 
7 
- 
; ; 
4 
5 
5 
i 
i 
i 
- 
me 
j 
t 
‘ 
Fr ‘ : 
Ne 


——————— T eee 
ee 
== 
— 


iw 
GNEISS @VARTZ- LIME- SLATE — 
ITE = - STONE 


i 


My 
| 


i 


mee oe ee eee 
errs” er 


GEOLOGY OF THE POUGHKEEPSIE QUADRANGLE 19 


of the town of Matteawan. The discussion of these may be fol- 
lowed by reference to the map of Matteawan (figure 8). 

The most western outcrop which has been noted is at the corner 
of Vail avenue and Washington street. The gneiss at this spot 
is very similar to that which composes the two inliers shown on 
the map at the northwest. Another outcrop occurs at the junction 
of Prospect and Mountain streets. A line drawn between these 
two outcrops marks the western boundary of the gneisses of the 
mountains, so far as they can be followed by actual outcrops. East 
of Washington street along Prospect, Union, Robinson and Alice 
thoroughfares and along Green, Park, Duncan and Goodrich side 
streets, outcrops are numerous. North of Mountain street the 
gneisses pass beneath the drift. A quarter of a mile to the north- 
east they are exposed again in the gorge of Mount Beacon brook. 
The reddish and greenish colors, characteristic of the Glenham belt 
and the inliers farther west, and frequent epidotic gneiss, were noted 
among the surface exposures of the gneisses just described. Other- 
wise these exposures are similar to the rocks in the Mount Beacon 
brook section. 

Mount Beacon brook section. Above and for a short distance 
below the bridge on Mountain street, near the foot of the mountain 
road, the brook has cut an interesting section in the gneisses. Just 
above the bridge the foliation and “ bedding ” planes strike n. 54° e. 
and dip about 75° s. e. Below the bridge the strike varies be- 
tween this angle and 69° e. of north. The rocks in this section 
show an isoclinal arrangement in “ beds” with high dip to the south- 
east. 

Below the bridge, the lowest portion of the section involves some 
forty feet of dark hornblendic gneiss. This rock is banded, though 
in places for the width of several inches it is massive. When water- 
moni, such suriaces present a spangled appearance. This 
“stratum ” is abruptly succeeded by a lighter colored one of much 
less uniformity of appearance. It is made up of imperfect alter- 
nations of granitic, quartzitic and composite “beds,” which vary 

~in thickness from the width of an inch or less to two feet. Some 
“beds” show light and darker bands. Others are uniformly light 
colored, often with little or no trace of a ferromagnesian constitu- 
ent. This “ stratum’ continues up stream for a hundred feet or 
more and passes beneath the bridge. It is succeeded by the Bald 
hill gneiss with varieties that strongly resemble the rocks of the 
Glenham belt and the Matteawan inliers in texture and mineralogy. 


20 NEW YORK STATE MUSEUM 


In the upper portion of the gorge above the bridge the north wall 
for some distance is a rusty, pinkish rock of fine grain and rather 
massive appearance. It resembles certain phases of the basal quartz- 
ite which have been noted outside the quadrangle, particularly the 
outcrops in the brook crossed by the mountain road a mile south of 
Dutchess Junction. This rock is jointed, and rests upon the gran- 
itic derivative of the Bald hill gneiss. 

Bald hill. The rock composing this spur of the Highlands was 
carefully examined along its base while tracing the quartzite, and 
also in two sections across its summit from west to east. One of 
these sections was made across the northern portion of the spur 
along an old wood road leading from the lane southeast of the 
Maddock farm near Glenham station. The other was taken partly 
along the road ascending Mount Beacon, then bearing to the left 
past the Graham place through “ Hell Hollow ” to the Cold Spring 
road. The rocks in the quarries near Mount Beacon reservoir, and 
in the excavations made for the new house at the summit of Beacon 
during the summer of 1908, as well as the section along the road 
‘descending from the reservoir to Matteawan, were studied. Com- 
parisons were made with the outcrops along the base of the ridge 
to the quarry at Storm King station and in the railroad cuts from 
Storm King to Cold Spring. An examination of other parts of the 
ridge of which Bald hill is the northern extremity, was necessary 
in order to form a clear idea of the character of the gneiss. 

Along the northwestern slope of the spur the gneiss is mainly a 
medium-grained, laminated hornblende rock with some micaceous 
variations. Along the basal portion of this slope the gneiss is usually 
rusty from included iron stains. Higher up it is commonly a drab 
or gray rock. The laminated character is more noticeable and the 
laminations are finer along the basal portion of the northwestern 
slope. Throughout most of the mountain the gneiss is rather 
coarsely or indistinctly foliated and in places is quite massive and 
granitic in appearance. 

The characteristic rock of Bald hill, as just described, is identical 
in texture and mineralogy with the rock in the quarry at Storm 
King station and with the prevailing type in the railroad cuts be- 
tween Storm King and Cold Spring. It is the chief variety in the 
quarries at Mount Beacon reservoir. 

At the excavations for the new mountain house on Beacon, the 
drab-colored granitic gneiss passed into a variety composed of ~ 
white feldspar and hornblende. In the hollow between Beacon 


Oe 


GEOLOGY OF THE POUGHKEEPSIE QUADRANGLE 21 


and Bald hills, along the road descending from the reservoir, the 
granitic hornblende rock is often very dark in color, which cor- 
responds with a greater freshness in the rock. 

The presence of cccasional micaceous variations has been noted. 
They are apparently confined to the more finely laminated portions 
of the gneiss and there is reason for thinking that the mica is 
secondary. The thin sections show abundant disseminated mag- 
netite which has become hydrated in many places, giving surface 
exposures a rusty color. 

The hemogeneous character of the Bald hill granite gneiss is 
noteworthy. In areal extent, it covers about eleven square miles 
east of the Hudson. The general igneous character of the rock is 
very impressive. The varieties that have been described would 
appear to be explainable as normal variations from a common 
magma. 

This rock is certainly of Precambric age. By its form and 
isolation it does not appear to have the character of a basal mem- 
ber. I have been unable to discover any other type which could 
reasonably be referred to this gneiss. If a basal formation, it 
should be of more frequent occurrence in these greatly eroded rocks. 
It therefore does not appear to be older than the other gneisses. 
All evidence of a possible unconformity would have been com- 
pletely obliterated. 

If contemporaneous with the other gneisses, on the assumption 
that they are sedimentary and that it is igneous and having the 
character of a sill, it should then occur also in other places to the 
east. It might be a laccolith, in which case it might have furnished 
the initial bulge at the time of folding. The more strongly banded 
character of the gneiss along the margin and the somewhat massive 
central portions might permit the interpretation of anticlinal 
structure. 

The pronounced alignment which this granite has with the other 
gneisses favors the view that it was thrust up into the gneisses at 
the time of their folding. All possible exomorphic and endomorphic 
effects would have been neutralized by the agencies of regional 
metamorphism. 

In addition to its other characters, the thickness of this formation 
is opposed to the idea that it is of sedimentary origin. 

The Mount Honness spur. A short distance east of the Cold 
Spring road in the hollow between this spur and Bald hill the rock 
resembles the Bald hill gneiss. In some places it is granitelike, 


22 NEW YORK STATE MUSEUM 


coarse-grained and only slightly foliated, looking like an altered de- 
rivative of the gneisses. The fault that borders Bald hill on the 
east may be within the Bald hill gneiss for a distance. 

North along the road toward Fishkill Village the rock becomes 
more foliated. A thin section of this variety shows some biotite in 
addition to hornblende, but the former is decidedly subordinate 
and is apparently secondary. 

Two mountain roads over this spur from the Cold Spring road 
to West Fishkill Hook give fair sections. There are also numer- 
ous outcrops in the fields to the north and south. Surface exposures 
are confusing both as to structure and petrographic characters. In 
some places the gneiss apparently dips to the northwest at low angles, 
but where the foliation planes may be detected, they dip to the 
southeast at high angles. The rock often has a granular and hybrid 
character that seems best interpreted as the condition resulting 
from the induration of a partially disintegrated rock which is pri- 
marily a very ancient character. The apparent northwest dip is 
accordingly best explained as a sort of exfoliation between the basal 
eneiss and the altered surface derivative. 

On the whole, the section is across a series of “strata’’ showing 
tendency to definite alignment with each other and to variety of 
composition. In the main the rocks of this spur may be classified 
as micaceous and hornblendic gneisses forming rather thick 


’ 


“ strata,’ which usually exhibit uniformity in mineralogy for some 
distance across the strike. 

The road from Brinckerhoff to Johnsville crosses this spur north 
of Mount Honness proper. Fine exposures have been made in the 
dark colored hornblende gneisses along the road in the process of 
constructing the new State road, and in the quarries just south of 
Arvis Haight’s, from which stone was removed. These sections 
show thick masses of the hornblende gneiss. Lighter colored 
gneisses have been noted interstratified with the hornblende 
varieties. 

In connection with the question of the origin of the hybrid char- 
acter of the gneiss along the northwestern slope of this spur it is 
interesting to note that the slope is gentle. Although it now lies 
in a faulted position against the limestone, the basal quartzite may 
have reposed on the gneiss along this slope subsequent to the eleva- 
tion which brought the gneiss against the limestone. | 

More distinct “ passage beds ”’ overlying the inclined gneiss occur 
just beyond the point where the two mountain roads cross on the 
crest of the ridge. Between the eastern fork of the roads thus 


J 


GEOLOGY OF THE POUGHKEEPSIE QUADRANGLE 23 


formed, west of the barn of Irving Knapp, thick masses, resem- 
bling both the gneisses and the quartzite in their mineralogy, dip to 
the north at a moderate angle. Farther along the road to the east 
of the house, ledges more closely resembling the quartzite were 
found. The woods and thick covering of drift, however, greatly 
obscure everything to and for a short distance beyond the west 
road into the mountains. South of the Carey farm, between the 
brook and the road, the quartzite was found grading downward 
into a hybrid rock. 

The Hook district. South of the quartzite slope, back of the 
farm of Garrett Smith, the thick woods obscure the succession in 
the gneisses and good outcrops are scattered. The outcrops in the 
field southwest of Alonzo Smith’s house (see plate 4) on the east 
road into the mountains and in the neighboring woods, are micaceous 
gneisses. Within the small space of the outcrop shown in the plate 
the gneiss passes from a rather coarse rock with quartz stringers 
through one with finer laminations into a purplish rock with still 
finer laminations. 

A comparison of the thin sections of these varieties shows a 
similarity as to essential “primary” minerals with biotite as the 
ferromagnesian constituent. The feldspar is chiefly plagioclase. 
Ouarkarts abuimecamt 
The degree of alteration 
of the primary minerals 
varies much. It is severe 
both in the feldspars 
and the biotite, but 
shows itself chiefly in 
taht eeliartatetraa ee eran tllare 
coarser gneiss the biotite 
is only slightly altered, 
while in the finely lami- 
nated purplish rock it is 
represented by masses 
of magnetite anda great 
abundance of finely 
granular material, prob- 
ably sericite, with only 
occasional traces of the boundaries of the original mineral (see figure 
9). The second variety mentioned shows a gradation between the 


Fig.9 Altered micaceous gneiss from the Hook district. 
Actual size 3 mm. Q, quartz; P, plagioclase; black, 
magnetite from biotite , 


24 NEW YORK STATE MUSEUM 


other two. The purplish color of the darker rock is plainly due to 
the abundant magnetite. 

Though apparently greatly decomposed, these rocks are firm 
and compact in the hand specimen. The magnetite is not altered 
into hematite or limonite. The conditions suggest that the altera- 
tion of these rocks dates back to an epoch preceding the deposition 
of the basal quartzite, which, as the proximity of this formation 
shows, formerly covered the gneisses, probably until glacial time. 

East of the east road into the mountains the quartzite has been 
dropped by a fault. It extends farther to the south than on the 
west of the road, partly on this account and partly because of a 
syncline at this point. No peculiar variations were noted in cross- 
ing the Hook spur to East Fishkill Hook. The southward exten- 
sion of the quartzite leaves comparatively few outcrops outside the 
thickly-wooded area of the spur. 

Shenandoah mountain.t Above the drift-covered slope of the 
quartzite, along the northwestern slope of the mountain, dark, 
micaceous gneisses were noted in conspicuous ledges. Along the 
road from the East Hook to Hortontown, these were succeeded near 
the summit of the mountain by a light granite interbedded with the 
gneisses and estimated to be from forty to sixty feet thick. I have 
called this the Shenandoah mountain granite. With the exception 
of one or two quartzitic members, the usual succession of the 
gneisses is crossed in going from the granite “stratum” across the 
mountain to Hortontown. On the whole, the micaceous types 
seemed more abundant. Outcrops are numerous along the road and 
in the fields on each side. 

The age of the granite can not be affirmed. It appears to have 
the strike of the adjacent gneisses; but it did not prove possible to 
trace it more than a few hundred feet. The quartzite formation, or 
its possible equivalent, was not found resting on the granite, so that 
its age could not be definitely assigned by showing an unconformity. 
If thrust up into the gneisses at the time of their folding, it has 
escaped foliation. It probably belongs to the Precambric series. If 
so, the absence of foliation indicates that Postcambric movements 
did not contribute to the characteristic foliation of the gneisses. 

The eastern gneiss mass. The rocks along the northwestern 
base of the eastern gneiss mass in some cases sttggest a continuation 
of those of Shenandoah mountain. 


1The spur next east is locally known as Shenandoah mountain, from 
the hamlet of that name at its northern termination. The Shenandoah 
of the map is East Fishkill Hook. 


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GEOLOGY OF THE POUGHKEEPSIE QUADRANGLE 25 


At Fowler’s kaolin mine, east of Shenandoah, a rock was found 


; beneath the kaolin deposits that was almost identical with the Shen- 
andoah mountain granite, though coarser in texture. The decom- 


posed rock, from which the kaolin was derived, is usually coarse, 


: showing quartz chunks the size of a walnut in a mass of altered 
_ feldspar. Probably the kaolin is the product of the disintegration 
: of a pegmatitic granite. The clay beds are apparently not very 
_ extensive, although their exact extent is obscured by glacial deposits 
_ along the slope. If the kaolin is thought of as the decomposition 
_ product of an arkosic, conglomeratic quartzite, it is difficult to 


account for the granitoid texture of certain specimens examined 


and the perfect résemblance which they have to the Shenandoah 


mountain granite. The quartz chunks are not rounded as one 


_ would expect in a conglomerate. A careful search failed to reveal 


the quartzite in the neighborhood. 
The structural features suggest that certain gneisses of this 


mass probably are faulted portions of the Shenandoah spur. Their 


resemblance might, of course, be explained as due to repetition. 
At Hortontown, near the quadrangle boundary, there were noted 


_ certain gneisses which had an almost unmistakable sedimentary ap- 


pearance. Though firmly crystalline, the quartzes frequently show 
a granular character on the fresh surface of the hand specimen, and 
the thin interlocking and dovetailing light and dark bands and fine 
texture indicate an impure sediment. There is nothing about such 
varieties that points to an altered igneous rock. 

The gneisses of the eastern mass were examined in their outcrops 
along the base of the northwestern slope, along the mountain roads 


and to some extent along the wooded summit. It did not prove 


possible to assemble them into an orderly series. They present 
irregular repetitions of hornblendic and micaceous gneisses with 


some few minor variations. The micaceous gneisses were the more 


— 


abundant. 

No decidedly massive types were noted. The thin sections are not 
conclusive as to the early condition of these gneisses, although in 
many cases they hint at altered sediments or ancient derivatives. 


THE GNEISS INLIERS 


The Glenham belt. The southern extremity of this belt 1s a few 
yards northwest of the dam at Groveville. Above the dam it forms 
the west wall of the gorge of Fishkill creek as far as Glenham. 
Northeastward it may be followed distinctly as a narrow belt as 


26 NEW YORK STATE MUSEUM 


far as Vly mountain. North of this hill it disappears against the 
, slates. The belt is bounded by the slates on the west throughout 
its entire length. Vly mountain is cut off from the main mass by 
a transverse fault which has offset the main belt to the west by its 
own breadth. This fault is occupied by a large swamp, to which the 
eminence probably owes its name. The mountain is bounded on 
the east by the slates and on the south by the Fishkill limestones. 
The latter border the main portion of the belt on the east to its 
southern extremity. The southern end of the strip is faulted against 
the slates. 

Mather called this mass a ‘ 


‘ 


granite rock ” in his description’ and in 


his section the “ Matteawan granite” (see plate 12, loc. cit.). He 
separated it from the gneiss of Bald hill, but apparently regarded 
it as a part of the Highlands. 

i. Emmons? cited this rock as an example of the uplift of in- 
ferior rocks into the newer ones. He described the relations at Glen- 
ham. His section is given herewith. 


Fig. 10 a, slate; b, granite (of Glenham belt); c, limestone; e, Fishkill mountain. (After Emmons) 


(Hall and Logan, in 1864, called it an ‘altered sandstone,” J) Di 
Dana, in 1870,* referred to it as “ bastard granite’ and described it 
as one of the “stratified deposits as is shown by its conformable 
position and by its taking the color of the slate near its junction.” 
The Highlands were the source. 

Smock in 1886° expressed doubts of its being stratified. He 
placed it with the Highlands, though the prevailing types of rock 
were unlike the characteristic varieties of the Fishkill mountains. 

In the southern portion of the Glenham belt the prevailing rock 
is a massive variety of the granitic gneiss. This is exposed for 
some depth in the railroad cut west of Glenham station. It is of 
dark green color and shows scarcely any tendency to foliation. 
South of this cut and for some distance to the north, surface out- 
crops are almost always of this type of rock, though varying in 


1 Geology of the First District, 1843, p. 437. 

2 Agriculture of New York, Part IV, 1846, p. 103. 

% Amer. Jour. Sci., Ser. 2, 39:07. 

“Amer. Jour. Sci., Ser. 3, 27 :386. 

* Thirty-ninth Ann. Rep’t N. Y. State Museum, p. 176. 


GEOLOGY OF THE POUGHKEEPSIE QUADRANGLE Be 


the degree of chloritization of the mica. It is without evidence of 
bedding. This rock grades in places at the south into a laminated 
finer-grained variety which is common in the gorge of the creek 
below the railroad bridge at Glenham. At the north this type is 
more abundant, outcropping frequently between the road from Fish- 
kill Village to Wappinger Falls and Vly mountain. 

Vly mountain is composed of this variety. It grades into the 
coarser rock and, like the latter, is usually chloritized, though the 
red color of the iron usually predominates. The laminations strike 
between n. 12° e. and n. 15° e. As was noted in the petrographic 
description of this gneiss, it occasionally passes into a rock com- 
posed only of feldspar and quartz. 

The varieties so far described make up the surface rock of the 
Glenham belt and are the ones which have been emphasized by 
most observers. 

The road from Fishkill Village to Wappinger Falls crosses the 

Glenham belt diagonally about midway of its length. Several shal- 
low cuts have been made in the gneisses along the road. Beginning 
at the first cut on the south, the section is through about one hun- 
dred feet of a coarse, granitic hybrid rock. This is followed by 
hornblende gneiss and at the top of the hill the latter is succeeded 
_by a banded, slightly crinkled gneiss with pinkish red and dark green 
laminae. A hundred yards beyond to the north of this rock on the 
west side of the road is a massive, coarse granitoid gneiss with 
quartz, light colored feldspar and biotite as the chief minerals. The 
joints in this rock are filled or faced with epidote. Beyond this is 
a fine-grained pinkish rock carrying epidote in many places and 
very similar in essential mineralogy to that described in the Mount 
Beacon brook section as composing the wall of the gorge above the 
bridge. Beyond this the cut is for some distance through medium- 
grained hornblende gneiss exposed on both sides of the road. The 
last section, on the east side of the road, is mainly through this 
hornblende rock which shows slight variations and fairly distinct 
“bedding,” with a southeast dip. 
_ These gneisses of the Glenham belt show no distinct types, except 
as described above for the surface exposures. On the other hand, 
the hornblende and other gneisses show marked resemblance to the 
mountain rocks. Roughly correcting the section for the gradient, 
the bearing of the road and the angle of dip, which seems a little 
smaller than that of the mountain gneisses, the thickness of the 
gneissoid types is similar to those observed in the gneisses of the 
spurs. 


28 NEW YORK STATE MUSEUM 


The Matteawan inliers. The coarse granitic rock so character- 
istic of the southern portion of the Glenham belt forms a small 
inlier farther south in Matteawan. It begins in “ Rock Hollow,” 
just west of the intersection of Washington avenue and the road 
that connects the latter with Liberty street, and extends south across 
Rock Hollow road (Walnut street) to Anderson street, and then 
as a narrower strip to Grove street. (See map of Matteawan, 
fig. 8.) The rock here is not quite so deeply chloritized as in the 
Glenham belt. 

Another mass of similar rock, about 700 feet long by 400 feet 
wide, lies to the south of this and forms the conspicuous knoll on 
which the Matteawan schoolhouse stands. The principal outcrops 
are between Spring, East and Falconer streets. This mass almost 
certainly connects with the gneisses in the eastern part of the town, 
but cutcrops are concealed along Mill, Louisa and Washington streets 
and Mountain avenue between this mass and the westernmost out- 
crop of the gneisses at the east. Limestone may overlie the gneiss in 
this interval. The latter outcrops between Woodall and Henderson 
streets, and presumably has or had an eastward extension from here. 

The first inlier described above is succeeded at the south by the 

basal quartzite which forms a knoll between Anderson, Walnut and 
Grove streets, and is separated from the Precambric on the north and 
west by Anderson street. The contact could not be found; it may 
be faulted. The quartzite is overlain by the limestone on the east 
and south and on the west for a distance of 75 feet north of Grove 
street. A small mass of slate has been faulted in between the lime- 
stone and the spur of the Precambric on the west of Anderson 
street, near the house of Mrs C. E. Phillips. 
_ At the northern end of the Glenham belt on the sone side of 
Vly mountain, north of the road at its base, a small knoll of quartzite, 
overlain by limestone, has been faulted with the gneiss of the moun- 
tain. It is separated from the main mass of foliated, reddish gran- 
itic gneiss by a narrow gully. 

As noted above, a coarse granitic rock of a mineralogy quite 
similar to that of the coarse granitic variety of the Glenham belt and 
the inliers at the south, occurs ‘in places in the bed of Mount 
Beacon brook above the bridge. It occurs in outcrops among the 
gneisses in the eastern part of the town and was noted on Prospect 
street, 50 feet north of its junction with Walcott avenue and at the 
corner of Vail avenue and Washington street. 

The mineral epidote is of frequent occurrence in the Glenham belt 
and in places among the gneisses in the eastern part of the town of 


GEOLOGY OF THE POUGHKEEPSIE QUADRANGLE 29 


iMiatteawan, and the rock which carries it in these different localities 
his often of very similar mineralogy and appearance in other 
respects. 

Interpretation. The Matteawan inliers connect the Glenham belt 
with the Highlands in a very satisfactory way. Other field relations 
which are cited above, show that the rocks composing these inliers 
care of Precambric age. The banded gneisses seen in the section 
‘on the Wappinger Falls road across the Glenham belt, bear strong 
‘resemblance to many of the gneisses outcropping in the town of 
“Matteawan along the base of the mountain. The hornblende gneiss 
‘in places is identical with those occurring on the road from Brincker- 
hoff to Johnsville across the Honness spur. When the dip may be 
observed in the gneisses along the Wappinger Falls road, it is prac- 

tically the same as that of the Highlands rocks. The essential 
identity as to the age and fundamental likeness in mineralogy and 
‘relations of these inliers with the Highlands is almost certain. 
_ The character shown by the rocks which make up so much of 
‘these inlying masses, and upon which most observers have dwelt, 
apparently admits of ready interpretation. 
_ During the time the early Paleozoic sediments of this region were 
being laid down the sea was progressively transgressing upon and 
overlappi g the old land mass from which its sediments were de- 
rived. This old land mass would doubtless have become decayed 
“for moderate depths beneath the surface, or at least would have 
“suffered some changes in the minerals composing the rock. Where 
“subaerial disintegration actually took place, its products may have 
‘remained undisturbed in favorable places, and it is possible to 
“imagine cnat they were finally covered by the advancing waters 
without having been much sorted. In other cases they would have 
been washed away, leaving only the firmer rock, which probably, 
rever, had undergone some mineralogical changes, such as the 
‘alteration of its ferromagnesian mineral. In other instances the 
disintegrated rock would have undergone partial sorting. In other 
cases it would have been completely sorted and a pure sandstone 
formed. In some places the advance of the sea would have been 
rapid enough to leave most of the material unsorted and only a 
superficial layer of partially sorted stuff. All would probably 
have been covered finally by a thoroughly worked over quartzitic 
sand that deepened offshore as the sea advanced. 
In the process of time burial in itself would have brought some 
changes in the subjacent altered gneisses; but the principal ones 
would have been effected by the same processes that changed the 


30 NEW YORK STATE MUSEUM 


basal sandstone to a quartzite and metamorphosed the overlying 
limestone and slate. The partly disintegrated upper portions of the 
gneisses would have been thoroughly indurated into a compact rock 
and probably partially recrystallized. The less altered gneiss would 
also have been changed, although not necessarily in such a way 
as to form entirely new minerals. Chlorite would now appear 
in a firm rock as a pseudomorph after biotite, or hornblende, and 
the old iron oxids would have been preserved as magnetite or hema- 
tite. In places where alteration had not taken place, the practically 
unchanged gneiss would be preserved. 

It is possible in this manner to account for the peculiar rock types 
of the Glenham belt and for the occurrence of such features as a 
coarse granitic “stratum” resting on upturned gneisses and fol- 
lowed by a somewhat foliated, finer-grained, quartzitic rock as shown 
in the gorge of Mount Beacon brook; or for the occurrence of such 
extensive surface developments of rock as the chief varieties of the 
Glenham belt, which so certainly rest upon and grade into the in- 
clined gneisses. Conditions would have been very favorable for the 
interaction of feldspars and ferromagnesians, which now find ex- 
pression in the abundant and widely distributed epidote that clearly 
belongs to an ancient period of alteration. 

A relatively large proportion of the ancient altered gneisses has 
been preserved in the Glenham belt. The section along the Wap- 
pinger Falls road, with its assemblage of altered and unaltered types, 
seems intelligible from this explanation. 

At places, as at Vly mountain, and near “ Rock Hollow ” in Mat- 
teawan, fragments of the quartzite have been preserved and these 
apparently grade into the underlying rock with which they are both 
unconformable and coextensive. 

These principles of subaerial decay have been applied in the 
foregoing discussion to certain altered gneisses and hybrid rocks 
occurring in many places among the Fishkill mountains. They serve 
to account for an evident ancient alteration in these recks and for 
the occurrence of certain types that are intermediate in character 
between the quartzite and the underlying gneiss: 


SUMMARY OF THE MICROSCOPIC CHARACTERS OF THE GNEISSES 


A microscopic examination has been made of about twenty-five 
sections of the gneisses of the Fishkill mountains, selected from 
types which were believed to show the principal variations in the 
gneissic series from west to east. A half dozen were also selected 
from the Glenham belt. 


GEOLOGY OF THE POUGHKEEPSIE QUADRANGLE 31 


These sections, except perhaps, those of the Bald hill granite 
gneiss and the Shenandoah mountain granite, do not afford any 
convincing evidence of the original character of the gneisses. They 
give some support to the inference made as to their alteration and 
afford some ideas of the age of different characters in the rocks. 
In instances, they bear out the character as seen in the hand speci- 
men and in the outcrop. In other cases, on account of the coarse- 
ness of the rock, they entirely fail to show the megascopic structural 
features. 

There are no striking variations in the kinds of “ primary ”’ min- 
erals present, except in the ferromagnesian, although the propor- 
tions vary. Quartz is usually present, frequently in large anhed- 
rons only, but oftener both as large and smaller ones. Sometimes 
it is absent from the section or quite insignificant. Plagioclase is 
universal, often with orthoclase, but occasionally alone in types 
with much ferromagnesian content and little or no quartz. Ortho- 
clase is occasionally in apparent excess of plagioclase and micro- 
‘cline is frequent. Biotite often appears alone as a primary constitu- 
ent, being clearly of the same age as the other essential minerals. 
-Hornblende often occurs alone in the same relationships. Buotite 
sometimes occurs with hornblende, but then often suggests a sec- 
ondary character from its distribution and subordinate amount. 

Magnetite is abundant and is evidently secondary. It occurs 
chiefly in irregular grains in bunches or as dust masses in or near the 
ferromagnesians, or scattered about the section within the feldspars 
and along fractures. It is occasionally pseudomorphic after the 
ferromagnesian. ‘The latter are plainly very ferruginous in char- 
acter. Zircons are numerous and widely distributed. Titanite ap- 
parently occurs as leucoxene about the magnetite at times. Chlorite 
is abundant, often replacing all or most of the ferromagnesians in 
the section, but this mineral is associated with the gneisses which, 
in the hand specimen, betray an ancient alteration. Muscovite or 
“sericite occur only as secondary minerals in the feldspar, except 
possibly in the Shenandoah mountain granite. 

_ The textural features present some variations, but they do not 
as a rule help much in deciding the question of whether the rock 
is sedimentary or igneous in origin. Very often the arrangement 
is very similar to that in plutonic rocks of the granitic or dioritic 
types and the modifications shown might readily be explained as 
due to conditions imposed on a magma. Other gneisses, either from 
a more granular character or from the abundance of the ferro- 
Magnesian mineral, suggest altered sedimentary types. But these 


sh 


32 NEW YORK STATE MUSEUM | 
’ 
features are plainly far from decisive. On the whole, the sections 
are less satisfactory than the field outcrops; but so far as they 
go they sustain the uncertainty of the field examination. ; 

If these gneisses are mainly altered sediments they have been sl 
thoroughly crystallized that they now often closely resemble igneous 
types. The hornblendes in their relation to the feldspars sometimes’ 
indicate a formation in the usual order of crystallization from a 
magma. If mainly of igneous origin, these gneisses were greatly 
squeezed in their formation and would now be more properly desig- 
nated gneissoid eruptives than eruptive gneisses. In either case the 
primary minerals (that is, those plainly belonging to the last change 
that affected the whole rock) and their essential arrangement are of 
contemporaneous origin. 

So far as examined, the sections are entirely free of the minerals 
usually found in areas of profound dynamic metamorphism. It is, 
of course, impossible to tell how many complete metasomatic or other 
changes these rocks may have undergone, but there appear to be no 
traces of any antecedent generations of minerals. 

The sections sustain the belief that the primary features of the 
gneisses, as a whole, are of very ancient character and of Precam- 
bric age. They show, on the other hand, many evidences of subse- 
quent metamorphism. 

This later metamorphism is shown in the sections in several ways, 
but chiefly as pressure effects. In almost all cases the quartz crystals 
show pronounced strain phenomena, such as strain shadows and 
wavy extinction, and are often cracked. The plagioclases almost 
always show pinched-out, bent or broken lamellae. Fractures and 
long cracks are common. In places where the gneiss evidently had 
undergone an early alteration, the rock was indurated and occasion- 
ally new minerals formed. Some molecular movement is indicated 
by chloritic fillings, disseminated magnetite and secondary quartz 
injected into the feldspars. Some biotite very clearly belongs to this 
later metamorphism. 

Some of the sections from the Bald hill gneiss and those in the 
bed of Mount Beacon brook show fewer appazent strain effects — 
than those from the spurs farther east, which may be interpreted 
as the expression within these rocks of a somewhat lesser degree 
of metamorphism at the west. The conclusion that the primary 
egneissic characters were changed very little in Postcambric time 
seems inevitable. As the field relations show the gneisses had reached 
practically their present crystalline condition and gneissic structure 


GEOLOGY OF THE POUGHKEEPSIE QUADRANGLE 33 


in Precambric time. Because of their early crystalline condition, 
these gneisses would have undergone fewer changes and a relatively 
lesser degree of metamorphism than the sediments which overlay 
them, during the mountain building process of Ordovicic time. Such 
changes as they underwent from this cause should, however, show 
some correspondence with those in the younger rocks, as is perhaps 
afforded in the apparent lesser degree of metamorphism at the west. 
This difference is not, however, noticeable in the field unless the more 
clearly “ bedded ” strata in the bed of Mount Beacon brook and the 
more clearly definable nature of the altered Precambric gneisses of 
the Glenham belt are indications of it. 

An examination of the thin sections of the gneissoid types from 
the Glenham belt entirely supports the assertion that these rocks are 
members of the Highlands gneiss series. In mineralogy, texture and 
metamorphic characters they are entirely similar. The thin sections 
of the more characteristic types of this belt afford the clue to their 
interpretation and seem to show their original nature. They also 
carry characteristic strain effects. 


FAULTS IN THE GNEISSES 


During the Green mountain uplift the Precambric gneisses appar- 
ently buckled somewhat, but seem to have yielded chiefly by break- 
ing. These faults greatly complicate the problem of the configura- 
tion of the Precambric land mass while the quartzite was being laid 
down. 

Beginning at the west, the first fault is that shown by the Glenham 
belt. A reversed or thrust fault has thrown the gneisses against the 
slates on the west and south. Evidently the slates were folded and 
overturned and then overridden by the older rocks. The strati- 
graphic displacement necessary to elevate the Precambric into con- 
tact with the slates must have been an extensive one. Apparently 
at Vly mountain the upthrust was greater, resulting in the elevation 
of the mountain mass above the main portion of the belt and caus- 
ing the transverse break between the two. That Vly mountain 
is not mainly an erosional feature is indicated by its relationships. 
It forms an isolated block which is faulted against the slates on the 
west, north and east. The transverse fault on the south involved 
the limestones which were bought against the slates on the east 
of them. The gneiss and limestone form the upthrow as a result 
of reversed faulting, both resting against the slate. The gneiss 
apparently also moved with reference to the limestone. Pro- 


34 ; NEW YORK STATE MUSEUM 


jected southward, the fault on the east of Vly mountain falls in line’ 
with the scarp on the east of Bald hill (see plate 5). 

The gneiss inliers in Matteawan, south of the Glenham belt, are 
also clearly faulted against the slates on the west. A long swamp 
borders the northern one of these on the west, while on the north 
it is in faulted contact with the slates. . 

The relationship existing between the limestone and the gneiss 
all along the eastern margin of the Glenham belt and the smaller 
masses at the south, is far from plain. Although relatively small, 
there is probably some stratigraphic displacement, in places at least. 

The Bald hill mass shows a still greater vertical displacement. 
As now uncovered, the break is partly within the gneiss itself and 
partly along a contact with the limestone, and probably in some 
places with the quartzite. The slope of the gneiss is always very 
steep and often precipitous. A moderate slope at the base, in 
places, may be interpreted as that of the quartzite or the surface 
from which it has been removed in late geological time. This kind 
of slope usually changes abruptly to a sharp angle with the vertical 
in ascending the mountain. The abundant talus at the bases of 
these scarps is misleading and gives the appearance of a much 
gentler slope than they really possess. The complementary result of 
recession of the summits by weathering is also confusing. 

Apparently the overthrust which elevated the Bald hill mass 
involved a larger area of the gneiss. It seems reasonable to explain 
the faulted contact of the gneiss of the Mount Honness spur and 
the Fishkill limestone on the northwest of it as primarily due to 
this thrust. Later or simultaneous tension faulting dropped the 
limestone east of Bald hill into its present position. A number of 
scarp faces at different elevations along the northwestern slope of 
the Honness spur in line with the strike of the gneisses, and visible 
even in the season of foliage, mark tension strike faulting of dimin- 
ishing intensity eastward from the great normal fault on the east 
of Bald hill. 

The eastern face of Honness is marked by a rather conspicuous 
normal fault scarp which diminishes and dies away to the south- 
ward (see plate 6). The throw here was not so great as on the 
east of Bald hill. 

Along the west side of the east road from West Fishkill Hook into 
the mountains, is a drop fault of small displacement. It is marked 
first by a cliff of the quartzite, but higher up the mountain it is in 
the gneisses. 


ITTY preg Jo ysvo ey} uo drvos ynviy 


GEOLOGY OF THE POUGHKEEPSIE QUADRANGLE 35 


y 
wa) 


On the east of the Hook spur another fault of moderate dis- 
placement has dropped the quartzite and limestone into the East 
ae 

The northwestern slope of Shenandoah mountain is very steep 
fom the point where it cuts the southern boundary of the quad- 
Bncte nearly to Shenandoah. The quartzite has a northwest dip 
‘Of approximately 50°. The gneiss in places shows precipitous 
Tedges, though these are not very high. The angle of slope changes 
abruptly from quartzite to gneiss. The steep dip of the quartzite 
shows considerable disturbance before the break occurred. 
_ East of Shenandoah mountain is a clearly defined normal fault 
‘scarp along which the younger rocks were dropped. ‘Their erosion 
thas formed Shenandoah hollow. 
_ Along the northwestern slope of the eastern gneiss mass are very 
steep and precipitous scarps, sharper even than those of Bald hill. 
he drift-covered talus slopes at their bases are not to be confused 
ith the quartzite. It is probable, however, that in places the 
‘quartzite was involved in the upthrow and was brought against the 


on producing the Green mountain elevation. ‘The tendency 
‘was to produce a system of flexures like those in the younger rocks 
at the north. The gneisses buckled relatively little but, unable to 
resist the great pressure, were broken and thrust up into the younger 
tocks. Tension faulting within the expanded arc accompanied 
or followed the upward thrusting. 

: The faulting in the gneisses is clearly subsequent to the de- 
Position of the quartzite. The only disturbance capable of produc- 
ing these effects would appear to have belonged to the close of 
Ordovicic time. 

; These faults would certainly have greatly disturbed any orderly 
Bence which the gneisses may have had. 

4 | 
K SUMMARY AND CONCLUSIONS 

_ The relatively brief treatment of the gneisses of this quadrangle 
given above results from the impossibility of assembling them 
into an orderly sequence. The thickly-wooded character of the 
country, the presence of faults and the difficulties introduced by 
ancient subaerial alteration, greatly hinder their study and make a 
Satisfactory map practically impossible. 

9 


al 


36 NEW YORK STATE MUSEUM 


The origin of the gneisses is very obscure. In some respects they 
appear to be largely igneous in character. In many places their 
sedimentary origin seems almost certain. It is entirely possible 
that the two kinds occur together in a parallel and roughly alternate 
arrangement, but faulting makes it impossible to decide this point 
in the face of the other difficulties present. The thickness is too 
great to permit the interpretation of a monoclinal series. 

It seems entirely justifiable to attribute the apparent igneous 
character to profound metamorphism. It is plain that if the 
gneisses represent a sedimentary series in any part, the strata must 
have been jammed into close folds and overturned. If folding 
was accompanied by the injection of igneous rocks along the axes 
of the anticlines, the accompanying alteration would have been very 
severe and both sedimentary and igneous types would have come 
strongly to resemble each other. There would probably be no dis- 
tinguishable exomorphic and endomorphic effects to aid in separat- 
ing the two. 

The gneisses below the bridge in the Mount Beacon brook section 
show a “ bedded” character more clearly than at any other place. 

The general absence of crumpling and crinkling in the gneisses is 
noteworthy in considering the possibility of their sedimentary origin. 

Interbedded limestones, if such could be found, were thought 
of as likely to afford the most convincing evidence of a sedimentary | 
series in these gneisses. Dr C. P. Berkey has discovered such lime- 
stones in the Highlands farther south’ and in the Fordham gneiss of 
New York city.2 The possibility that the basic rock and bastite 
ledges at Hortontown, described in the following pages, might be 
altered calcareous and magnesian sediments of Precambric age 
was considered, but the field relations do not easily permit this 
interpretation. 

Taken as a whole, the gneisses in this quadrangle present sufficient 
diversity to be considered, at least in part, as an altered sedimen- 
tary series. 


NAME AND CORRELATION 


Dr C. P. Berkey® has correlated the basal member of the Man- 
hattan series with the basal gneisses of the Highlands and has 


1Structural and Stratigraphic Features of the Basal Gneisses of the 
Highlands. N. Y. State Mus. Bul. 107, 1907. 

2 Science. n. s., 37 :036. 

8 Structural and Stratigraphic Features of the Basal Gneisses of the 
Highlands. N. Y. State Mus. Bul. 107, 1907, p. 361. 


PLISIP YOOFT JSOAA\ PY} WoT; Uoos sv ‘ssouUOTF] JUNOT FO JsVo 9Yy} UO divos yNeYy 


Q 231PTO 


GEOLOGY OF THE POUGHKEEPSIE QUADRANGLE 37 


called the whole the Fordham gneiss. This he correlates with the 
Grenville of Canada and the Adirondacks. 


SHE HORTONTOWN BASIC ERUPTIVE AND 
ASSOCIATED METAMORPHIC ROCKS 


General relations. In the orchard by the house and near the 
‘barn on the farm of Albert Lawrence at Hortontown, are several 
outcrops of a massive, compact, greenish rock. One or two ledges 
‘are of moderate size, but most of the outcrops are small and incon- 
‘spicuous. This rock is traceable only a short way fo the north or 
south by actual outcrops, but in the fields and stone walls south of 
‘the orchard there are numerous boulders of this rock. The actual 
ledges disappear beneath the hill to the southwest of the orchard. 
At the summit of this hill, in a west by southwest direction from 
‘the house, and about 200 or 300 yards away, are numerous ledges 
of a rusty, blackish rock, which may be followed to the southwest 
for a short distance and then are lost. Just to the west of these 
‘outcrops, on both sides of the road and in the road itself, are numer- 
ous outcrops of quartzite with southeast dip and a strike east of 
north. A conspicuous ledge of this quartzite borders the west side 
of the road. West of this is a gully about 50 or 75 feet in width 
which at the west is bounded by a perpendicular cliff of the 
gneisses. The relationships just described are indicated on the 
accompanying sketch map (see figure II). 

It was not possible to determine the configuration of the mass 
to which the greenish rock belongs. The east-west distance be- 
tween outcrops was estimated at 50 feet, but there is reason for 
thinking that the rock has a greater extent. 

Petrography and general description. The greenish rock is very 
tough. It shows variations from a greenish black rock, streaked 
with lighter green, through a mottled variety to a lighter, greener 
rock with a tendency to fibrous structure. 

_ The rock may be cut with a knife. Some varieties, when pol- 
ished, give a rich, dark, glossy finish. When powdered and tested 
by the magnet it reveals large quantities of magnetite to which the 
darker hues are due. Weathered surfaces show freckles of black 
and greenish yellow, caused by the bleaching of the microscopic 
crystals among the magnetite grains. The thin section in transmitted 
light shows innumerable dustings and irregular grains of magne- 
tite, while the rest of the section is yellowish white. With crossed 


38 NEW YORK STATE MUSEUM 


$ 


nicols the latter appears as a network of spindles, flakes and needles 
of bastite. There seems to be no trace of an antecedent mineral 
(see figure 12). . 7 
The ledges of them 
black rock are prevail- 
ingly rusty. Excavation 
has been made at one 
place to a depth of two 
or three feet, apparently 
in a search for ore. 
These ledges are in- 
conspicuous, and, when 
surrounded and over- 
grown by grass, are 
readily missed, except 
in systematic search.’ 
The hand _ specimen 
shows avery coarse tex- 


ture. The rock is made 
Fig. 12 Bastite rock at Hortontown. Actualsize 3 mm. ; : 
Showing a network of bastite needles and spindles with up chiefly of massive 


apy at Wars ih hornbiende. There are 
patches of finer texture in which magnetite is abundant. Small 
pyrite grains are frequent. In some places the hand specimen 
shows a relatively porous mass of rounded grains as though some 
mineral had been dissolved away. The rock has a high specific 
gravity and in almost all cases is rusty in color. The thin section 
shows large, irregular pleochroic brown and green hornblendes, with 
some pyroxene. Magnetite inclusions are numerous and this min- 
eral also occurs abundantly along numerous cracks, sometimes in 
association with serpentine borders or fillings. 

The ledges of the quartzite are more numerous and more ex- 
tensive than those of either of the other rocks. Its apparent width 
is about 75 or 100 feet. It is thin-bedded and steeply inclined. It 
is very similar to the basal quartzite as seen at certain places and 
appears to belong to that formation. It may be followed distinctly 
for several hundred feet. 

At the north and south these types give way to the characteristic 
gneisses of the mountains. 

The exact field relations of these rocks are very obscure. No 
contacts could be found. Seemingly the only clue to their age and 
relationships is to be obtained from the structural features and the 
associations. 


—aas 


| 
| 


SS SSS 
OR IE 


aA 

vv NEY, 

| I bey WV Os 
BASTITE QUARTZ BASIC GNEISS 


ROCK ITE E RU PTIVE 


Fig. 11 Sketch map to show the general relationships at Hortontown. Scale 
approximately 200 feet to the inch. 


GEOLOGY OF THE POUGHKEEPSIE QUADRANGLE 39 


Interpretation. The possibility suggested itself that some of 
these rocks might be members of the basal gneiss series. The 
quartzite, however, is almost certainly Paleozoic in age. The black 
hornblende rock has the characters of a basic eruptive. The green 
serpentine variety gives little idea of its original character, but it is 
apparently not an altered pyroxenic rock. 

The southwestward continuation of the reversed fault along the 
northwestern slope of the eastern gneiss mass would apparently 
intersect the fault on the east of Shenandoah mountain in this 
neighborhood. The latter scarp is only a short distance west of the 
quartzite. This intersection would have been a most favorable point 
for an igneous intrusion. Some of the basal Paleozoics were evi- 
dently caught at this intersection and intruded by the hornblende 
rock. The quartzite offered little for the eruptive to act upon. The 
bastite rock very probably represents an impure ferruginous dolo- 
mite. From what is known of bastite, it is commonly, at least, the 
alteration product of orthorhombic pyroxene; but the present rock 
gives no indication of the former presence of any antecedent min- - 
eral. There seems to be no grave objection to the inference that 
the passage was direct.* 

This is the only occurrence within the quadrangle that permits 
the interpretation that an eruptive has penetrated and altered the 
overlying Paleozoics. 


was Ves OUNwI Zl iE (POUGHOUAG) 


Distribution and general structural features. This formation, 
which has frequently been mentioned in connection with the 
gneisses, in this quadrangle occurs only in proximity to the Pre- 
-cambric rocks. 

In the town of Matteawan the quartzite forms a small inlier as 
described above, in connection with the first small inlier of gneiss 
south of the Glenham belt (see page 28). Outcrops were also seen 
just north of Howland avenue in the open field at the foot of the 
Mount Beacon incline. The only other outcrops which have been 
noted in this vicinity occur farther north along the base of Bald 
hill on the Maddock estate.2 About 300 yards south of the house 
and well up in the woods, about 200 or 300 feet east of the private 


1 Professor B. K. Emerson assisted the writer in the identification oi 
the mineral bastite. 

* The presence of the quartzite at this point was discovered by a com- 
panion, Mr W. R. Clarke, 


40 NEW YORK STATE MUSEUM 


drive, are two or three good-sized ledges. Farther up the hill on 
Mountain street at the point where it forks, going east, is an outcrop 
of the quartzite. This was first interpreted as a boulder, but the 
proximity of this rock in place farther down the hill suggests that 
it is a small ledge which has been preserved. These outcrops are 
the only ones which were noted in this town, after a careful search, 
which were referable to the quartzite as typically developed in this 
quadrangle. 

As has been discussed above, there is strong reason for thinking 
that certain phases of the gneiss owe their peculiar character to 
the subaerial decay and partial sorting which took place during the 
epoch of the transgression of the sea in which the quartzite was 
laid down, and are therefore of the same general age. 

At Vly mountain a small patch of the quartzite has been pre- 
served just north of the road on the south side of the mountain at 
the summit of the hill as the road descends into the swamp, going 
west. 

A careful search was made along the northwestern base of Bald 
hill from the Maddock farm to the northeastern end of the spur. 
The topography between the more precipitous portion of the hill and 
Fishkill creek often suggests the presence of the quartzite. Out- 
crops are few and the gentler basal portions of the slope are usually 
drift-covered. The foliated Bald hill gneiss outcrops in places north 
of the Maddock residence between it and the farmhouse at the north- 
east. Outcrops are absent at the base of the gneiss to the northeast 
of this farm, nearly to the end of the spur. The ledges of gneiss often 
rise precipitously from the edge of the gentler portion of the slope 
and the bases of the scarps are hidden by abundant talus which, in 
many cases, doubtless forms the gentler slopes. Near the extremity 
of the spur, due south from Fishkill Village, a ledge of the quartzite 
was discovered in the woods near the edge of the gneiss. The gneiss 
extends to the north of this ledge. 

The Bald hill thrust carried the quartzite with it in places before 
the rupture occurred and in these places a characteristic quartzite 
slope has been preserved. Only a few scattered ledges now mark 
the former presence of this formation in the eastern part of the 
town of Matteawan. The small ledge near the extremity of the spur 
seemingly belongs with the upthrow block and probably rests by 
thrust against the limestone. It is a question whether the precipitous 
ledges of the gneiss northeast of the Maddock farmhouse rest 
against the quartzite or the limestone. 


GEOLOGY OF THE POUGHKEEPSIE QUADRANGLE Al 


The map represents the quartzite slope, with the break to the 
southeast of it passing into the limestone southwest of the Maddock 
farmhouse. Northeast of that point it shows the gneiss against the 
limestone for a distance as indicating the tendency of the thrust, 
and then against the quartzite, with a probable break between the 
quartzite and the limestone. 

There are no traces of the quartzite south of Fishkill Village in 
the valley of Clove creek, nor along the northwestern base of the 
Honness spur. Along the northwestern base of Mount Honness 
proper the gneiss is only 50 or 100 feet from the limestone, from 
' which it rises in bold ledges. The quartzite may once have covered 
a portion of the northwestern slope of this spur. 

East of Honness, about one-third of a mile south of Johnsville, 
the compact quartzite with some conglomerate outcrops for a short 
distance in the woods at the base of the scarp, but is soon lost 
beneath the kames which rest against the cliff. South of these 
kames on the farm of Irving Knapp, as mentioned above, a large 
mass of rock with northerly dip forms conspicuous ledges in the 
east fork of the mountain roads. It resembles both the quartzite and 
the gneiss and probably represents a transition from one to the 
other. The quartzite outcrops along the road east of Knapp’s, in one 
or two places, but is mostly concealed by drift west of the west road 
from the Hook into the mountains. It was found in the bed of the 
brook just west of John Ireland’s house and about 300 yards south 
of the Thomas Carey farm on the roadside just above the brook. 
Some conglomerate occurs at this point. Eastward from the Carey 
farm, on the farms of Garrett Smith and Ward Ladue, it forms 
large conspicuous ledges and extends to a point one-fourth of a 
mile south of Garrett Smith’s and terminates with an abrupt talus 
slope in the woods. The unconformity between the quartzite and 
gneiss is plainly shown just south of Alonzo Smith’s (see plate 4). 
East of the east road into the mountains, the quartzite extends a 
little farther south before the gneisses are reached. The southern 
boundary swings round northwest of the McCarthy place and then 
east through the woods across the Hook spur to the fault on the 
east of this. At this point the quartzite was dropped by a fault and 
is now concealed by surface deposits nearly to the quadrangle 
boundary. Just north of the road on the west side of the brook 
it appears in large ledges. Low ledges of limestone outcrop in the 
meadow just east of the brook. 

Near the quadrangle boundary a small brook, which comes down 
from Shenandoah mountain, has cut through the surface deposits. 


42 NEW YORK STATE MUSEUM 


The quartzite was found exposed well up the slope in the bed of this 
brook dipping 50° to the northwest with a strike of n. 49° e. 
following closely the strike of the ridge. For a mile and a half to 
the northeastward this formation forms a clear topographic feature, 
though concealed by drift. Farther on it outcrops frequently and 
in large ledges along the south side of the road from the East Hook 
to Shenandoah. It crosses the road less than one-fourth of a mile 
west of that hamlet and is succeeded by the gneisses. There are 
numerous outcrops of the quartzite just north of Shenandoah. It 
is probably cut off at the east by the fault that borders the mountain 
on the east. 

The quartzite is absent along the eastern base of Shenandoah 
- mountain until one reaches the mass associated with the basic 
eruptive at Hortontown (see page 39). 

Along the northwestern slope of the eastern gneiss mass the 
topography from the schoolhouse near Hortontown to Fowler’s 
kaolin mine suggests the presence of this formation. The quartzite 
was not found and the lower portion of the slope is covered with 
drift which contains frequent large quartzite boulders. The kaolin 
rock at Fowler’s mine may represent the quartzite. It seems likely 
that the gneiss rests against the limestone southeast of Shenandoah, 
and that the quartzite has since been eroded. South of the junction 
of the Hortontown and Mountain roads, gneiss is the outcropping 
rock in the valley of the brook as far as Hortontown. 

Along the slope of the eastern mountain mass, northeast of the 
kaolin beds and the ore deposits, everything is beneath the drift for 
a long distance at the base of the mountain. The gentle slope which 
is present is probably due to talus. No outcrops of the quartzite 
were found. South and southeast of Charles E. Bailey’s the lime- 
stone is only a short distance from the precipitous gneiss. Just 
north of the road at the base of the mountain scarp, east of Bailey’s, 
a wide swamp extends northeastward. Three-fourths of a mile east 
of the point where this road turns southward into the mountains 
the quartzite was found in good-sized ledges within the edge of the 
woods. 

The conditions along this slope resemble those described for Bald 
hill. ‘There was a tendency for the quartzite to fold somewhat 
before the rupture occurred, and the slope of the hill marks the 
slope of the quartzite as seen southeast of Shenandoah. Toward 
the northeast the rupture occurred earlier, so that the gneiss now 
stands in precipitous ledges against the limestone. Farther on, east 


GEOLOGY OF THE POUGHKEEPSIE QUADRANGLE 43 


of Bailey’s, the quartzite was brought against the limestone marking 
a diminishing tendency in the thrust to the east. As shown on the 
_map portions of the quartzite are yet preserved near the quadrangle 
boundary. Where the quartzite could not be found the gneiss is 
represented as resting against the limestone; but in some cases, as 
discussed above, the quartzite may have once been present. 

The wide swamp east of Bailey’s marks the northeastward con- 
tinuation of the great thrust fault along the limestone-quartzite 
contact. é 

Petrography and general description: This formation has 
great uniformity of appearance and general character throughout 
the area. Its principal variations may be stated very briefly. The 
predominating variety is a compact, granular quartz-rock of medium 
grain. This grades into a fine conglomerate at the base in a few 
places and in others at the top into finer-grained quartzitic shales. 
The predominating variety is either white or pinkish in color. 
Feldspathic varieties are rare. 

Within the quadrangle there does not appear to be any apprecia- 
bie difference in metamorphism in this formation from west to 
east. At the type locality at Poughquag there is indication of a 
gneissoid character. Within this quadrangle the quartzite appar- 
ently never was involved violently enough to induce this structure. 

The thin-bedded varieties, often with shaly character, were noted 
at the northern end of the Hook spur south of the Hupfel estate, 
in the steep bed of the brook in the East Hook near the quadrangle 
boundary, north of Shenandoah and at Hortontown. Conglomeratic 
phases were seen southwest of Johnsville near Honness mountain, 
south of the Thomas Carey farm in the West Hook and north of 
the McCarthy place to the east of Ward Ladue’s. 

Strikes and dips in this formation vary greatly. In Matteawan 
good observations could not be made in the thick quartzite south of 
Anderson street nor at the foot of the Mount Beacon incline. Read- 
ings taken just south of the Maddock residence gave a strike of 
mse and a “dip of 54° n. w. Ihe gneiss, only 30 
feet away, dipped 50° to the southeast. Observations at the 
quartzite ledge at the extremity of the Bald hill spur gave a strike 
Mid A2. ec. and) a dip of 48° to the northwest. A. reading 
taken on the east of Honness gave a strike of n. 42° e. and a 
dip of 35° southeast. South of the Carey farm in the West 
Hook the dip is 15° to the northeast. On the farms of Garrett Smith 
and Ward Ladue, west of the fault, the dip is to the north- 


4A NEW YORK STATE MUSEUM 


west. East of the fault it is to the northeast. As the boundary 
swings round the western slope of the Hook spur, the dip changes 
from northeast to north and northwest, and at the northern end 
of the spur from northwest to north. On Shenandoah mountain 
in the East Hook, near the quadrangle boundary, the strike is 
n. 49° e. and the dip 50° n. w. This general strike and dip 
holds to Shenandoah. North of Shenandoah the dip changes to 
north. The quartzite disappears at the east under a mass of kames. 
Readings made a mile east of Bailey’s gave a strike of s. 70° e. 
and a dip of about 18° n. e. 

The quartzite thus follows the folds of the gneisses and, although 
eroded and disturbed by faulting, tends to fringe the spurs and 
hollows along the northern margin of the Highlands. 

The conformable series at West Fishkill Hook. East of the 
normal fault that extends along the east road into the mountains, 
the basal quartzite is overlain by bluish-gray limestones having 
the same dip as the quartzite. The nearest approach to actual con- 
tact is in Ward Ladue’s orchard, a few feet north of Jones’s barn. 
The pinkish ledges of granular quartz rock are only a few feet 
away from the limestone and the two are seen to be in strict con- 
formity. The limestone, which is greatly broken up into large blocks, 
can be followed to the south and east. In both directions it is suc- 
ceeded by the quartzite. The limestone swings round the north- 
western slope of the Hook spur and appears in numerous ledges 
in the fields southeast of W. L. Ladue’s barns. Here it is con- 
formably overlain by gray calcareous shales. At the eastern side 
of the pasture, south of the orchard on W. L. Ladue’s farm, the 
shales dip to the northwest and north. A little farther west, in the 
center of the field, the interbedded shales and shaly limestones have 
buckled into a low anticline. 


wer 
WENGE 

; CENT: a7, 

Precambric Le RRS 


Fig. 13 Generalized section to show the conformable series of the Lower Cambric in the West 
Hook district. Distance approximately one-third of a mile 


Fossils from the quartzite and overlying limestone. With the 
exception of a few worm borings found in the quartzite along the 
west road from the West Hook into the mountains in the summer 


GEOLOGY OF THE POUGHKEEPSIE QUADRANGLE 45 


of 1906 (see figure 14), fossils had not been discovered in this 
formation up to the summer of 1909. 

In August of that year the writer 
discovered in the yard of Ward Ladue 
at the West Hook a fossiliferous slab 
Of compact quartzite, about three 
feet square, and plainly derived from 
a bed about five inches thick. Both 
surfaces were covered with fossils, 
chiefly brachiopods and the cephalic 
borders and spines of trilobites. Some 
of the latter were from one and one- 
half to two inches long. 


Pisa awaS TrOmlyia ime-Sraimed. — icc sworn borings in Lower 
gray quartzite bed and was very compact CS es 
and resistant. The fresh surface showed numerous rusty markings. 

This discovery led to persistent search for the fossiliferous rock 
in place. 

Directly south from Ward Ladue’s house a gorge in the quartz- 
ite apparently marks the beginning of the normal fault displacement 
that extends southward just to the west of the public road. The 
western wall of this gorge is composed of thickly bedded compact 
quartzite. The eastern wall shows thianer rusty layers interbedded 
with the compact rock. The fact that only a hundred feet or so to the 
eastward the quartzite is overlain by the limestone, together with the 
evidence of faulting, were taken to indicate that the rocks in the 
eastern wall are younger than those on the western or upthrow side. 
With this assumption as a basis, and in the belief that the rusty 
layers interbedded in the superficial portion of the quartzite should 
yield fossils, if such were present, the eastern wall was given a very 
careful examination. No fossils could be found between Ladue’s 
and the point where the gorge intersects the road. Although the 
dip of the quartzite is very gentle along here, the thickness crossed 
is considerable. 

The gorge was then traced southward from the road. A rich 
assemblage of fossils was discovered in the eastern wall about 250 
yards southeast of Herman Adam’s house. The ledge occurs just 
beneath an old stone wall that separates the gully from an old 
orchard. The fossil traces were first discovered in the compact 
rock similar to that seen in the slab in Ladue’s yard, and showing 
the same rusty markings on the fresh surface. This rock overlies 


40 NEW YORK STATE MUSEUM 


some thinner, rusty, decomposed layers in which fragments of 
trilobites and brachiopods are very abundant. ‘The trilobite 
fragments are smaller than those displayed on the slab described 
above, but in other respects are quite similar. They were identified 
as fragments of Olenellus, probably thompsoni. The 
brachiopods bear a strong resemblance to Obolella. Two speci- 
mens of the rusty quartzite crowded with fossils are shown in 
figure I5. 


Fig. 15 Fossiliferous Lower Cambrie quartzite 


In the summer of 10908 the* opercula of El ysoiiiaimere aire 
micans were discovered in the limestone overlying the compact 
quartzite in Ladue’s orchard at an estimated distance of 20 feet 
above the latter. After a careful search another operculum was 
found at a slightly higher level in the first ledge east of the lower 
barn on Jones’s farm. 

Age and correlation. These fossils prove the quartzite to be 
of Lower Cambric age. The similar relations which it has to the 
underlying gneiss indicate that it is the equivalent of the basal 
quartzite at Poughquag. The latter was described and named by 
Prof. J. D. Danat as the Poughquag quartzite. 


1 Amer. Jour. Sci., Ser. 3, 1872, 3 :250-56. 


GEOLOGY OF THE POUGHKEEPSIE QUADRANGLE 47 


Summary and conclusions. The relationships among the 

quartzite, limestone and calcareous shale described above are ex- 
hibited nowhere else in this quadrangie. 
- The field relations of the gneisses and the quartzite indicate that 
the older rocks have been thrust up into the younger series and 
that in general their present relative position must be regarded as 
very different from that which obtained when the Cambric sea over- 
lapped the older land. It is plain that the quartzite was involved 
in the thrust movement and, although never violently folded, was 
yet greatly disturbed by folding in certain places. In many instances 
the quartzite was moved bodily with the gneisses, so that where it 
is now present, or was apparently present up to a comparatively 
recent epoch, it is not contiguous with the limestones of its own 
epoch, but with later ones on which it has been thrust. 

A not unreasonable restoration of the Precambric floor, which 
is thus assumed to have been fractured and elevated, would allow 
a considerable extension of the thick quartzite formation south- 
ward from its present northern position. The actual evidence for 
such a former extent consists in the faulted mass at Hortontown, 
which, since the thrust movement was northwestward, could hardly 
have had an original position farther northwest, but which might 
readily have come from the southeast, and in occasional ledges 
observed in the woods during a reconnoissance south from West 
Fishkill Hook across the quadrangle boundary. The character of 
the slope of the quartzite where least disturbed, as in West Fishkill 
Hook, its thickness: and the rather steep southern termination at 
certain places, indicate a former southward extension. 

The varying strike and dip of this formation is best interpreted 
as the result of disturbance subsequent to its deposition, rather than 
to original initial slope. 

In attempting to explain the present valley position of the 
younger rocks along the northern border of the Highlands, instead 
of assuming that they were deposited in valleys, we are offered 
the alternative explanation of down-faulting, and subsequent partial 
- or entire erosion in which the ice sheet may have played an import- 
ant part. 

The Precambric masses may have stood as isiands in the early 
Paleozoic sea, but the present relationships do not require such an 
interpretation. 

The disturbance of the quartzite has given it such inclination that 
it might be regarded as of different geological age at different 
‘altitudes. Of this there is no evidence. 


48 NEW YORK STATE MUSEUM 


THE WAPPINGER (BARNEGATE) LIMESTONE 


This formation appears within the quadrangle in two main belts” 
with some smaller faulted masses lying between them. The west- 
ernmost main belt is the Barnegate limestone of Mather,’ but now 
commonly referred to as the Wappinger creek or New Hamburg 
belt. It is followed by Wappinger creek from the latter’s source 
near Pine Plains to the Hudson river, and its eastern contact with 
the overlying “ Hudson River” formation crosses the river at New 
Hamburg. The eastern belt is known as the Fishkill limestone, 
as it lies chiefly in the town of old Fishkill. 


THE WAPPINGER CREEK BELT 


This belt enters the quadrangle from the north at Pleasant Valley 
and continues in a southeast by south course to New Hamburg. 
It reappears west of the Hudson and continues in the same direc- 
tion beyond the western boundary. East of the Hudson it is broken 
up into a central strip, with a large rectangular strip on the west 
of this along its southern half and separated from it by a narrow 
band of the slates, and several smaller masses lying to the east of 
the central strip along its middle portion. 


THE WESTERN STRIP 


Boundaries. ‘This strip is clearly faulted against the slates at 
the north. The fault line runs in a southeast-northwest direction 
across the Poughkeepsie driving park. The western contact is 
marked at many places by swamps or scarps which indicate that 
the western margin is also a faulted one. The presence of a fault 
along here receives confirmation from the apparent age of the lime- 
stone in contact with, or in proximity to, the slates. The western 
boundary begins just southeast of the junction of Hooker avenue 
and the road that runs southward from it on the west of the driving 
park and passes across the northwestern part of the Ruppert farm 
and just west of the old Hinckley house, and then may be traced 
by swampy ground or a low scarp to the schoolhouse at the corner 
of the Spackenkill and Poughkeepsie roads; thence under drift to 
the first road leading to the river. The limestone outcrops on the 
north side of this road in low-lying ledges and in more conspicuous 
ones south of it in proximity to the slates. From here the contact is 


1 Geology of the First District, 1843, p. 410. 
2This fault was described by Professor W. B. Dwight. See Amer. 
Jour. Sci. Feb. 1886, 31:125-37, with map. 


GEOLOGY OF THE POUGHKEEPSIE QUADRANGLE 49 


indistinctly followed to the river, where the limestone terminates in 
a bluff. The northern portion of its eastern boundary is concealed 
by drift, but farther south to the east of the road that runs south- 
ward on the east of the driving park the limestone forms a con- 
spicuous feature for several hundred yards along the eastern edge 
of R. J. Kimlin’s farm. Southwest from here it apparently follows 
Casper creek to the Hudson river. The slates which come in 
between it and the central strip form conspicuous ledges both north 
and south of the Spackenkill road and were noted southwest of the 
Poughkeepsie-Wappinger Falls road, on the east side of the road to 
New Hamburg, and also near the Hudson river. The lower 
reaches of Casper creek, west of the Poughkeepsie road, are choked 
with kame deposits. 

Terranes present. The Potsdam and Trenton horizons have 
been recognized in the strata composing this western strip of 
limestone. 

The Potsdam. Fossils belonging to this horizon have been 
discovered in a few places. The first were reported by Professor 
W. B. Dwight" from the northern portion of the strip. Just south 
of the Poughkeepsie driving park, and to the west of the new pri- 
vate road which runs south from the park to the Ruppert farm- 
house, are a number of low-lying ledges. They have yielded: 
MetiMcaihe pis pinnitormis, L. minima; L. acumi- 
miso molella, (lineculelia) prima, Obolella 

_ resembling “nana, Platyceras, Ptychoparia (Cono- 
cephalites) n. sp. Dicellocephalus, Ptychaspis, Stromato- 
cerium, encrinal columns.” A few months later Professor Dwight 
reported other Potsdam fossils from a locality about a mile 
southeast by south on the Spackenkill road, about one-half mile 
east of the Ruppert farmhouse, at the point where the private 
road to the Varick farm leaves the main road. In addition to 
Lingulepis pinniformis and allied species found at the 
first locality, he identified Ptychoparia saratogensis 
Walcott, and P. calcifera Walcott. These fossils may be 
seen in the museum of the Vassar Brothers’ Institute at Poughkeep- 
sie. Another ledge yielding L. pinnifcormis was found by 
Professor Dwight near the eastern margin of the belt about one-half 
mile southeast of the first locality described.* This ledge is just east 


1 Amer. Jour. Sci. Feb. 1886, 31:125-37. See also Trans. Vassar Bros. 
Tnst., 4:130-41. 

2 Trans. Vassar Bros. Inst., v. 4, pt. 2, p. 206-14. 

3 Amer. Jour. Sci., July, 1887, 34 :28-32. 


50 NEW YORK STATE MUSEUM 


of the little house north of Mr R. J. Kimlin’s barn. The ledge 
carrying Solenopora compacta found by Professor Dwight — 
is only a short distance to the southeast. ; 

In the summer of 1908 a new Potsdam locality was discovered — 
by the writer. The beds yielding fossils were found in the quarry 
on the Ruppert farm about 200 yards north of the Spackenkill road. 
The rock was being removed for lime and blasting operations greatly — 
facilitated the search for fossils. These are scattered and usually 
fragmentary. They are embedded in compact, resistant limestone — 
which made the search difficult. A half dozen good specimens of — 
Lingulepis pinniformis were found, besides numerous © 
fragments; also a head of Ptychoparia sp. A photograph of 
the quarry is shown in plate 7. Fossils seemed most abundant in 
the middle layers. Figure 16 shows two of the best preserved speci- 
mens of L. pinniformis. 


Fig. 16 Two specimens of Lin gulepis pinniformis from the arenaceous Upper Cambric * 
‘ limestone beds at Ruppert’s quarry 


The rock in the floor of this quarry showed many peculiar mark- 
ings of concentric rings from three-fourths to one inch in diameter. 
These were sectioned and examined by Professor John M. Clarke. 
A part of a letter from Dr Clarke referring to these structures is 
given below. 

“T have had the specimen you sent to me cut and polished in the 
hope of bringing out some structure from the concentric masses 
therein. The result is not very satisfactory, except as indicating 
what seems to be an inorganic origin, though I would not be willing 
to say that the masses were not spongoid like Streptochaetus. The 
successive laminae might indicate such a structure, but the intimate 
composition of the skeleton has been so altered by granulation as 
to seem to leave possibility of organic structure pretty hazy; yet I 
am inclined to believe that the rock carries organic remains, as 


‘ds ersedoyo4}q pue Sitwioyruurd eyn Sui‘, PoplatA oavy stoke] s[pprur ay, ‘SoM oY} OF Ayyysis dip 
spoq aseyy, ‘osdsayxysnog JO Jsvoyynos Wet sjioddny ye Arienbd oy} UL Spoq o1iquie) Joddy) [ejuOzZTIOY 4sowye oY} SUIMOYS 


GEOLOGY OF THE POUGHKEEPSIE QUADRANGLE 51 


indicated by apparent fragments of shells seen on polished surfaces 
and in section. I return these specimens to you for your ex- 
amination. I notice that one side of the rock specimen exposes 
something that suggests a head of Conocephalus or other primitive 
trilobite.” 

Figure 17 is a photomicro- 
graph of a section of this rock 
and shows what appears to bea 
fragment of a tiny shell. The 
microscope failed to bring out 
any structure in the concentric 
masses. 

In addition to the suggestive 
marking referred to by Doctor 
Clarke as possibly representing 
a trilobite cephalon, the writer 


noted another strongly suggest- 
ing a Hyolithes. 

The rock layers in the floor of the quarry are about ten or twelve 
feet below the layers yielding L. pinniformis and the whole 
are conformable. 

The Trenton. This horizon; as mentioned above, was reported 
by Professor Dwight from the eastern margin of the belt on the 
farm of R. J. Kimlin and was recognized by the presence of 
molenopora compacta. No other localities have been 
described. 

Petrographic characters and further description. The Potsdam 
rock in the locality first reported by Professor Dwight was described 
as varying from a tough compact limestone through fissile, shaly 
argillaceous types and arenaceous and oolitic limestones, into quartz- 
itic varieties which were sometimes brecciated. All were calcareous. 
These may be verified for the most part. The calcareous quartzite 
is often friable from the loss of the carbonate and rusty from iron 
discoloration. It frequently carries shell-like depressions or molds. 
Along the western margin of this strip large quantities of sand 
are dug and shipped away for molding purposes. In appearance, 
it strongly suggests the rusty quartzitic phase of the Potsdam of 
this western strip. As favorable a place as any for observing this 
sand is on the farm of Mr Toel on the Camelot road north of 
Casper creek. 

A section beginning at the eastern margin of the belt, just south- 
east of R. J. Kimlin’s farm, and running west along the Spackenkill 


Fig. 17 Showing a thin section of the lime- 
stone in the floor of Ruppert’s quarry 


52 NEW YORK STATE MUSEUM 


road to the Poughkeepsie road, and then continued to the river 
along the road to the molding sand dock a mile and a half north of 
Camelot,’ and thence along or just east of the track to Camelot 
station gives all the principal varieties of rock that have been met 
with north of Stoneco quarry. 

Beginning at the east, south of Kimlin’s farm, at the top of the 
hill on the Spackenkill road, the rock in the ledges is of a light 
steel-blue color and of medium grain (letter A in the section, fig. 18). 


/ 5 PoTSDAN ty 
R’s qu CSHALY 
CHERTY paconice ¢ ARRY) LIMcsToNE 


Fig. 18 Section along the Spackenkill road 


It often carries on fresh surfaces markings of calcite, shaped like 
the segments of various curves, and blackened depressions and pits 
which have no particular or definite form. Just north of the junc- 
tion of the two roads at this point on the east side of the road that 
passes Kimlin’s house a brecciated conglomerate was noted re- 
sembling the Trenton as seen elsewhere in the quadrangle and carry- 
ing masses that resembled Solenopora compacta. 

The next cut west on the Spackenkill road shows many chertlile 
masses and scroll effects of silicious material that have weathered 
out. North of here in the fields of Mr Mulkemus and in the neigh- 
boring woods the ledges carrying this variety of rock are very 
numerous and may be traced some distance east and west (let- 
tered) By ite? 18): 

This rock gives place, near and at the junction with the Varick 
road, to dull gray ledges of arenaceous limestone which has a coarse 
sandpaperlike appearance on weathered surfaces. One-fourth mile 
beyond this, rock outcrops on the north side of the road and lies 
quite flat (lettered C, fig. 18). Whe rock at Ruppenticmanaenes 
one-fourth mile farther west (lettered D, fig. 18), in general 
character is almost identical with that of the two previous outcrops. 
The rock in the quarry varies in color from black to gray. The beds 
average thicker at the base and grow thinner toward the top. There 
are a few shaly layers. The strike of the quarry rock is about 
n. 75° e. and the dip about 10° northwest. 

At the corner of the Spackenkill and Poughkeepsie oe im- 
pure limestone outcrops on the east side of the latter road with 


1Camelot station is at the point marked Stoneco on the map. The 
name Stoneco is usually applied to the Clinton Point Stone Company’s 
quarry, a mile below Camelot station. 


GEOLOGY OF THE POUGHKEEPSIE QUADRANGLE 53 


a strike of n. 23° e. anda dip of 70° s.e. This may belong with the 
slate formation and may therefore be on the downthrow side (let- 
fered F, fig. 18). 

Ledges of rock similar to that in Ruppert’s quarry occur to the 
southeast along the western margin of the belt, to the north and 
south of the first road leading to the river, and west of the road 
leading from this toward Camelot station. East of Camelot sta- 
tion, about 100 feet up the hill, on the south side of the New 
Hamburg road, ledges of rock identical with that in Ruppert’s 
quarry strike approximately east and west and dip about 12° to 
the south. 

The first road leading to the river, south of the Spackenkill road, 
leaves the Poughkeepsie road (old Albany turnpike) one-fourth 
mile south of the schoolhouse. The river road gives off two 
branches, the shorter, lower one going to the dock of the White- 
head Sand Company and the other to Camelot station. 

On the east side of the lower road, just north of the red house, 
coarse conglomerate, familiar in Trenton localities within this quad- 
rangle, outcrops in one or two large ledges. This rock, in a brec- 
ciated condition, was also noted farther south along the upper road 
where this runs parallel with the railway track, about one-fourth 
mile north of Camelot station. 

Along the middle portion of this western strip the topography 
generally indicates a very gently sloping almost flat substratum of 
rock, and the extraordinary width of the belt is plainly due to the 
nearly horizontal position of the underlying strata for long distances. 

The varieties of rock described by Professor Dwight would 
seem to be accounted for mainly as outcrops across the dip of several 
beds showing variations of texture and composition, and partly to 
the different effects of weathering on these, as well as to possible 
frictional brecciation. 

The portion of the section 
which may be seen at Stoneco 
in the quarry of the Clinton 
Point Stone Company is be- 
tween one-fourth and one- _£ 
third of the breadth of the 
strip from its eastern margin 
and displays a thick mass of dolomitic limestone dipping gently to 
the west (see plate 8). For the most part it is thick-bedded. There 
are some thinner layers near the top and in the middle. Some beds 
carry numerous chertlike masses and in this particular, as well as in 


Fig. 19 Section at Stoneco quarry 


54 NEW YORK STATE MUSEUM 


general character, the rock strongly resembles the variety described 
above along the Spackenkill road on the farm of Mr Mulkemus 
near the eastern margin of the belt. No fossils were found in the 
beds of this quarry and hence no definite idea of its age could be 
obtained. 

Just east of Camelot station, as described above, arenaceous lime- 
stone identical with that in Ruppert’s quarry, dips to the south at 
an angle of 12°. This suggests a southward pitch and a superior 
position for the strata in the Stoneco quarry, a mile to the south 
of Camelot. 

The stratigraphic position and estimated thickness of the Stoneco 
beds agree with those of the cherty rocks along the Spackenkill 
road to the northeast. Presumably these strata once entirely 
covered the Upper Cambric (Potsdam) along the central and 
western portions of the strip and have been preserved at the south 
on account of the pitch of the series. 

Structural features. It is not possible to tell with absolute 
certainty what the exact relationships are among the different strata 
composing the series of this western strip. Presumably the Upper 
Cambric beds are followed conformably by those which apparently 
have a superior stratigraphic position. But in these latter strata 
it is necessary to recognize a probable interval of erosion as is in- 
dicated by relationships which can be determined with more exact- 
ness within the central strip and which is shown by the presence 
of a conglomeratic layer, even in this western belt. As will be 
discussed farther on this conglomerate, though possessing peculiar 
features, marks a change in fauna as well as in the lithic character 
of the rock and must be taken as marking a definite hiatus. 

The present almost horizontal position of the Upper Cambric 
and overlying beds theoretically admits of two explanations. It 
either represents a close overturned, recumbent fold, or else a 
reversed fault accompanied by westward thrusting, which was pre- 
ceded by only relatively little folding. 

These rocks show no indications of extensive slickensiding, of 
compression of layers, or of flow structures such as would be ex- 
pected in violently folded strata. There is evidence of some brec- 
ciation and slipping in the rock along the eastern margin, but this 
is not severe. There is extensive fracturing which is, however, 
readily explained by the hypothesis of reversed faulting and thrust- 
ing. 

The field relations point to an upward movement of older strata 
into overlying younger ones similar to that already described for 


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Q 231810 


are 
. eds 
2 


GEOLOGY OF THE POUGHKEEPSIE QUADRANGLE 55 


the gneisses. Along the western margin of the strip the compres- 
sion brought the Upper Cambric beds against the slates, which were 
first folded and overturned and then overridden. At the quarry 
at Stoneco and below Marlboro station across the river the west- 
ward dipping younger strata show a diminution in the upward thrust 
toward the southwest which may be associated with an earlier re- 
lease that elevated the Glenham belt. 

As already indicated, the conglomerate appears in places along 
the western margin of the strip. It is best interpreted as belonging 
with the downthrow block and is to be associated with the slate 
rather than with the limestone. It is likely that there was a strong 
horizontal component in the thrust that carried the older beds over 
the slates to the west of this strip. 

The conglomerate alcng the eastern margin would appear to 
occupy a normal position, but the fact that it is brecciated is note- 
worthy. The presence of ledges yielding Lingulepis pinni- 
formis, as described above (see page 49), along the eastern 
margin in the near neighborhood of the Trenton, seems best ex- 
plained as an instance of faulting. The Potsdam beds seem clearly 
to have been overlain by younger strata, as is now the case at 
Stoneco quarry. It does not seem possible from the relationships 
exhibited elsewhere that the overlying strata were eroded so as to 
expose the Potsdam before the deposition of the Trenton. 

Apparently the 
limestone on the west 
of the Hudson is es- x 
sentially the continu- SE 
ation of this western ~~ 
strip, but presumably 


Fig. 20 Section at Danskammer 


‘the beds are younger even than those of the quarry at Stoneco. 


Some of them resemble the beds of the central strip, as shown at 
the New Hamburg 
tunnel. On the west 
of the Hudson, near 
the = iivers. edge. at 
Danskammer, the 
limestone dips to the 
southeast at an angle 
Ct lO. wi longs tae 
western margin, as 
shown just below Marlboro station, the dip is to the northwest. 
The limestones rest by overthrust on the slates at the west. 


Fig. 21 Section below Marlboro station 


56 NEW YORK STATE MUSEUM 


Metamorphism and alteration. Brecciation has been noted 
along both margins of the strip. Fracturing has been extensive, pro- 
ducing many small cracks that have been healed by calcite. The 
broken surfaces of the rock along the eastern margin of the strip 
show by the smooth, distorted blackened depressions that there has 
been some movement in the rock. The alteration is least where the 
beds are flattest. The principal changes then are due to granulation 
which usually has been sufficient to conceal or destroy organic 
remains. 

Summary. Presumably the Upper Cambric beds are followed 
in this strip by the Beekmantown (Calciferous), as is the case in 
the central strip; but fossils belonging to this horizon have not yet 
been discovered. This terrane may be represented by all or part of 
the dolomitic strata shown in the Stoneco quarry and their apparent 
equivalents to the north.t 

Locally about Saratoga a very fossiliferous limestone lens appears 
in the basal portion of the dolomite formation.? 

The trilobites discovered by Professor Dwight on the Spackenkill 
road, as mentioned on page 49, were like those discovered by Mr 
Walcott at Saratoga.® 

No fossils have been reported from the limestone on the western 
bank of the Hudson within this quadrangle. In 1879 R. P. Whit- 
field* reported Maclurea magna from these  limestonesman 
Newburgh and in 1880 W. B. Dwight’? found an assemblage of 
Trenton fossils in that city. 


1The description of the cherty, dolomitic limestone at the Stoneco 
quarry and overlying the Potsdam beds along the Spackenkill road was 
written in October 1909. At the meeting of the Geological Society at 
Cambridge, Mass., the following December, Professors Ulrich and Cush- 
ing described a dolomite in the Mohawk valley which “is found to con- 
sist of two distinct formations, the lower a dolomite formation of Ozarkic 
age, the upper a limestone of Lower Beekmantown age with a distinct 
unconformity between the two.” The Beekmantown was described as 
thinning to the west, so that west of Little Falls the Lowville rests on 
the Ozarkic. The unconformity may be followed into the Champlain 
valley, reappears in the St Lawrence region “and is believed to mark 
the line of division between the two formations everywhere in northern 
New York.” 

2Preliminary list of papers. G. S. A., 22d winter meeting at Boston- 
Cambridge, December 19009. 

3 See Thirty-second Ann. Rept. N. Y. State Mus.; also U. S. G. S. Bul. 30, 
p. 21, and Science, 1884, 3 :136-37. 

4 Amer. Jour. Sci., Ser. 3, 18 :227: 

5 Amer. Jour. Sci., Ser. 3, 19 :50-54. 


GEOLOGY OF THE POUGHKEEPSIE QUADRANGLE 57 


THE CENTRAL STRIP 


Boundaries. This strip enters the quadrangle from the north 
at Pleasant Valley. Its eastern margin forms the western bank of 
Wappinger creek north of the covered bridge at Pleasant Valley 
and southward follows the creek closely as far as Rochdale. At 
this place the limestone is in contact with the slate at the dam and 
on the island just below it. South of Rochdale the limestone fol- 
lows the creek for one-half mile and then bears slightly to the west. 
It apparently ends just north of the terrace one-fourth of a mile 
east of Tompkins’s house (see plate 17) on the Pleasant Valley road. 
This terrace fringes an old meander of the creek and extends around 
to the south side where the limestone appears again just south of 
the road that skirts its edge. East of the portion of this road run- 
ning north and south, just west of Frank De Garmo’s house, are 
numerous outcrops of the slates, but these disappear at the terrace 
slope and no outcrops appear in the deep westward embayment 
formed by the old meander. 

This embayment is regarded as lying in a zone of transverse 
faulting. It seems probable that the slates were dropped down in 
here. At any rate, either on this account or because of faulting, a 
weakness was produced which the base-leveling forces caught and 
finally left as a gap in the ridge of limestone. It seems probable 
from the dimensions of certain faulted limestone blocks a short dis- 
tance to the eastward that they belong in or near this gap. The 
slate has been dropped between the faulted masses and the dis- 
membered main strip. 

South of the break in the central strip its eastern margin follows 
the road until the latter turns eastward and then extends as a con- 
spicuous wooded scarp in a north and south line to a point about 
one-third of a mile south of Frank De Garmo’s house. At this 
point the limestone sends a sharp angular spur eastward for about 
200 yards, as shown on the map. The strike of the slates just west 
of De Garmo’s house, projected southward, would bring them sharply 
against the limestone in the included angle of this spur, showing a 
transverse fault between the slates and the spur and indicating that 
the eastern marginal scarp south of De Garmo’s is a faulted one. 

Limestone outcrops at the apex of this spur, whence it may be 
traced by continuous outcrop along the margin of the slate to and 
across the railroad track and highway west of Manchester Bridge. 
South of here the eastern margin follows the eastern base of an 
immense drumlin and south of this distinctly to the Poughkeepsie- 


58 NEW YORK STATE MUSEUM 


New Hackensack road; then across this and for a short distance 
to the south. The margin is then apparently broken by a spur in 
a manner similar to that just described, although this time the break 
appears to be along an extensive fault line. The slates which out- 
crop south of the Poughkeepsie-New Hackensack road and west of 
the cross road that leads from it to the Spackenkill road, lie in the 
included angle of this spur. 

The contact is then easily followed southward by the steep mar- 
ginal scarp in the limestone, from the.point where the cross road just 
mentioned makes its turn, to and across the Spackenkill road, and 
east of the old Boardman farm. The gully which, as shown on the 
map, cuts across this central strip west of the northern termination 
of the narrow faulted strip lying on the east, may represent a fault. 

South of the Spackenkill road slates outcrop in numerous places 
between the main strip and the narrow faulted mass just east and 
south through the swamp to the southern end of the small strip, 
leaving no doubt but that, at the surface, the two limestone masses 
are separated by a narrow band of the slates. The eastern contact 
is then very readily followed through the fields to Channingville 
and then less distinctly under the drift between the creek and the 
New Hamburg road to the bank of Wappinger creek near its junc- 
tion with the Hudson. 

The western margin of the central strip could be determined with 
much more exactness in certain places than in others. At the north 
the surface deposits conceal it for the most part, but swamps and 
other topographical features and occasional outcrops enable one to 
follow it approximately, and in a few places distinctly, until it 
crosses the Pleasant Valley road just west of Rochdale. The lime- 
stone then forms a distinct scarp east of the road to the break just 
southeast of Tompkins’s house. South of this the margin is distinct 
to the railroad, but across this it is soon lost under the drift com- 
posing the large drumlin at this point. The limestone reappears 
on the south side of this hill and again a little farther south as a 
scarp which crosses the Poughkeepsie-New Hackensack road. 
South of this road the margin is readily followed, often with the 
limestone and slate in close proximity, to the Poughkeepsie-Wap- 
pinger Falls road which, going south, ascends the western scarp of 
the limestone. South along the New Hamburg road the contact 
is clearly for a distance on the east side of the road as the slate was 
noted in the latter. But along here the kame deposits effectually 
conceal the exact relationships between the limestone and slate. At 
the northern end of. the New Hamburg tunnel the limestone rests 


GEOLOGY OF THE POUGHKEEPSIE QUADRANGLE 59 


by overthrust upon the slate (see plate 9) and occasionally the 
limestone outcrops along the slope to the northeast for a short 
distance. 

Terranes present. The Potsdam, Beekmantown (Calciferous- 
Rochdale group) and Trenton horizons have been identified along 
this central strip within the quadrangle. 

The Potsdam. This horizon was first noted in this strip just 
a little north of the quadrangle boundary half way between Pleasant 
Valley and Salt Point. At Pleasant Valley Lingulepis pin- 
niformis was reported along or near the western margin of the 
strip to the northwest of the village in rather characteristic argil- 
laceous limestone, and also from some hills to the north of the vil- 
lage between the old Poughkeepsie and Eastern Railroad bed and 
Wappinger creek.? At the latter place the beds carrying L. pinni- 
formis also had small brachiopods, apparently Orthis and Tri- 
plecia, as well as minute gastropods, fragments of trilobites and 
Ophileta compacta. These beds were mixed with Calci- 
ferous and Trenton strata carrying other fossils characteristic of 
these limestones in this region. The Potsdam was identified near 
Rochdale, just west of the Poughkeepsie-Pleasant Valley road. The 
beds exposed in the quarry just northwest of Alson De Garmo’s 
house, from which stone was removed for the State road, are pos- 
sibly of Upper Cambric age. A search for fossils in this quarry 
was unrewarded. In a note to his paper on the discovery of Pots- 
dam fossils in Poughkeepsie, south of the driving park, as described 
for the western strip, Professor Dwight* mentioned the discovery 
of a fragment of brachiopod shell which he believed to be that of 
Seinsulepis pinniformis in.a rock very similar to that 
at the locality south of the driving park. He described this new 
locality as about one-half of a mile south of the Boardman mansion 
on the Spackenkill road, but it is uncertain from his description at 
just what point the fossil was found. 
~The Beekmantown (Calciferous-Rochdale group). In Jan- 
uary 1880, Professor Dwight* reported the discovery of a rich 
assemblage of fossils of Pretrenton age at Rochdale, a small fac- 
tory hamlet four miles northeast of Poughkeepsie. 


1W. B. Dwight. Amer. Jour. Sci. July, 1881, 34:27-32. 

2(W. B. Dwight) J. M. Clarke. Guide to the Fossiliferous Rocks of 
New York State. N. Y. State Mus. Handbook 15, p. 9-10. 

3 Amer. Jour. Sci., Feb. 1886, 31 :136. 

4 Amer. Jour. Sci. January, 1880, 19:50 et seq. 


60 NEW YORK STATE MUSEUM 


The following named fossils were enumerated as the most im- 
portant: 

“Ophileta complanata (possibly Ophileta com- 
pacta), ©. levata, O. sordida (Qlaceltieawer. 
dida), Orthoceras primigenium.” @Othem names 
were noted but not identified. A network of “ fucoidal fronds ” 
might be Bythotrephis antiquata. The fossils of the 
neighboring Trenton at the east were absent from this rock and it 
was believed to lie beneath the Trenton, both strata having an east- 
ward dip. It was called the Calciferous.* 

In October 1880, Dwight? found at the Rochdale locality another 
remarkable assemblage: “ great numbers of Orthocerata and other 
fossils, many of which are not reported as occurring in New York 
State.” In lithology this rock was identical with that previously 
assigned to the Calciferous. Orthocerata were abundant and dis- 
coidal gastropods very plentiful. In addition to its own peculiar 
fossils, it contained the “ fucoids ” and other types of the adjacent 
Calciferous. Dwight hesitated to announce the exact stratigraphical 
position of this new fossil assemblage. The wealth of cephalopods 
separated it very sharply from any other known terrane in the 
United States below the Black River-Trenton, to which it was in- 
ferior. In its numerous orthoceratite cephalopods it resembled the 
Quebec group of Canada. 

In 1882 Diwght* reported tracing the ‘Calciferous in this strip to 
a point five miles below Poughkeepsie. In addition to the above- 
named “ Calciferous ” fossils he announced in this paper: A large 
Holopea and smaller ones not identified, many Pleurotomaria re- 
sembling Canadian forms, a minute Ophileta n. sp., a Mur- 
chisonia resembling gracilis of the Trenton, one or two orthides, 
many undeterminable fragments of Bathyurus, Chaetetes ly- 
coperdon var. ramosa, not hitherto reported below the Tren- 
ton, 25 to 30 species of Orthocerata, all apparently new in the 
United States, two species of Lituites and a Cyrtoceras. In 1884+ 
a number of these fossils were described with figures; trilobite frag- 
ments were provisionally assigned to the genus Bathyurus (B. 


1 The ledges at the summit of the hill north of Alson DeGarmo’s house 
on the Pleasant Valley road belong, in part at least, to Dwight’s Calci- 
ferous locality. 

2 Amer. Jour. Sci., Ser. 3, 21:78. 

3 Proc. Amer. Assoc. Adv. Sci. (Montreal meeting), v. 31. Abstract Aug. 
1882, p. 3-6. 

4Amer. Jour. Sci., Ser. 3, April, 1884, 27 :249-50. 


GEOLOGY OF THE POUGHKEEPSIE QUADRANGLE 61 


taurifronsand B.crotalifrons). New cephalopod species 
mene described as Cyr-toceras vassarina, C. ? dacty- 
aoc. microscopicum, Orthoceras apissi- 
meme, ©. henrietta, Oncoceras vassiforme. 

In 1900 Dwight! designated the main Calciferous strata as the 
Cyrtoceras vassarina beds and called attention to the great 
persistence for a distance of nearly thirty miles in the Wappinger 
limestone, of a layer which contains a fauna quite different from 
that of the main beds. It lacked cephalopods entirely. There were 
no important fossils in common in the two beds except two or three 
always present in the Calciferous. In some respects it resembled 

the Fort Cassin of Vermont, but differed in the extreme scarcity of 
cephalopods. The presence of Lingulepis pinniformis 
suggested a low horizon in the Calciferous. What Dwight has called 
a low horizon in the Calciferous may be Upper Cambric discon- 
formably overlain by Beekmantown. 

The Trenton. Fossils belonging to this horizon were the first 
to be discovered in the Dutchess county limestone und were hrst 
reported from the area within this quadrangle. 

Mather referred only in a footnote to their having been found in 
a quarry south of Pleasant Valley by Professor Briggs. His assign- 
ment of the age of this formation was based on fossils found in 
the beds of limestone within the slate formation a mile or so north 
of Barnegate. 

In 1879 Professor Dwight? found the following Trenton fossils 
@eexocudaic: Leptacna (Plectambomites ) sericea, 
Mcihis tricenaria, Receptaculites sp. - A week after 
the discovery Dwight and Dana visited this locality. The following 
mesilse were found: L. (P) sericea, Kscharaporarecta, 

tilodictya acuta, the caudal shield of a trilobite probably 
Pera pimis vettstus, Orthis trieemaria, O; pec- 
Zomciia, ©. £esttidinarfria, an Mndoceras, an Orthoceras, 
specimens of Chaetetes, and encrinal columns.? On this same excur- 
sion the quarry south of Pleasant Valley, mentioned: by Mather, 

‘was visited. A fossil assemblage very like that at Rochdale was 
at once discovered. Subsequent examination of this collection 
showed Strophomena alternata fragments. inte 
Chaetetes was named by Dwight C. tenuissima. 


1 Bul. Geol. Soc. ‘Amer., v. 12, 1900, abstract. 
2 Amer. Jour. Sci., May, 1879, 17 :380. 
3 Amer. Jour. Sci., May, 1879, 17:390. See also p. 381. 


62 NEW YORK STATE MUSEUM 


In 1880 Professor Dwight! added to the above from the Roch- 
dale locality: a number of cyathophylloid corals, among them 
Petraia corniculum, a head of Echinoemenmmuaee 
anatiformis, and the caudal shield of a trilobite identified as 
Itlare nus aiciaass sic auudeay The C.. tenuiSisi ime 
identified as in part at least, Stromatopora compacta 
Billings (Chaetetes compacta Dawson). This fossil is 
now recognized as Solenopora compacta. 

The Trenton also occurs at Pleasant Valley in the railroad cut 
just east of the Central New England station on the old Pough- 
keepsie and Eastern road. The Trenton beds here have yielded 
Tetradium cellulosum and great numbers of entomostraca 
and fragments of small trilobites.2 The characteristic Trenton con- 
glomerate carrying Solenopora compacta occurs at the 
northeast end of the cut. The Trenton apparently has an extension 
eastward in the village. The conglomerate carrying fossils was 
noted by the writer at the hose house. 

It is quite probable that other Trenton localities in later years 
were noted by Professor Dwight which were never published. 

Petrography and further description. Beds from this strip, 
which have been referred to the Potsdam, vary from argillaceous to 
arenaceous limestones with occasional shaly layers. It is not pos- 
sible to say much about the extent of the Potsdam along this strip 
to the south. It may occur at many places for which, however, there 
is at present no paleontologic evidence. The structural features 
suggest that it is probably confined to the northern and central por- 
tions of the strip and that the beds at the south are probably younger. 
The shaly limestones in the quarry west of the tunnel at New 
Hamburg have been thought to be of Potsdam age on stratigraphic 
grounds. . 

The Beekmantown (Calciferous) of this strip is best studied at 
its type locality at Rochdale. It is often, if not characteristically, 
arenaceous and varies in color from a bluish gray to a gray with 
lighter chamois-colored layers which weather very white. The two 
are interstratified, though the writer’s observations indicate that the 
bluish beds are usually near the eastern margin and therefore in 
the upper layers. The bluish beds carry grayish wavy markings and 
are very tough and splintery, breaking with conchoidal fracture. 


1 Amer. Jour. Sci., v. 19, January 1880. 
2(W B. Dwight) J. M. Clarke. Guide to the Fossiliferous Rocks of 
New York State. N. Y. State Museum Handbook 15. 


GEOLOGY OF THE POUGHKEEPSIE QUADRANGLE 63 


The lower portion of the Calciferous shows many thick, grayish 
layers in places. 

Apparently the Beekmantown has a wide distribution in this 
strip. It forms the main mass of the high hill northwest of the 
Trenton in the cut at Pleasant Valley and may be traced rather 
satisfactorily as a lithic unit to Rochdale, where it is seen to have a 
great thickness, estimated at from 1000 to 1200 feet. Dwight 
claimed to have traced it definitely to a point five miles below 
Poughkeepsie (see above). The beds resting on the slates at the 
New Hamburg tunnel are probably of Beekmantown age. 

At Rochdale the Beekmantown in places passes through a heavy 
conglomerate into the Trenton which rests upon it. Just a little way 
south of a ledge of this conglomerate on the property of Henry Titus, 
along the road, are fine exposures of the bluish-gray beds. These give 
place at the west to the gray and dove-colored beds which compose 
most of the hill between Rochdale and the Pleasant Valley turnpike. 

The bluish-gray beds were noted farther south near the eastern 
margin just north of the break in this strip. Taking the apparent 
thickness at Rochdale as a guide, the beds intervening between these 
biue beds and the scarp just east of Tompkins’s house are probably 
all Beekmantown. South of here the lithology does not convey 
very much, though indicating on the whole the southward continu- 
ation of the lower portion of the Beekmantown as shown at Roch- 
dale. 

Within this strip farther south, about one-fourth mile north of 
the Spackenkill road, along an old wood road, or cow path, are 
probable beds of the Beekmantown within a few rods of coarse 
Trenton conglomerate apparently carrying Solenopora com- 
pacta. The road from the orchard on the north side of the 
Spackenkill road, opposite the old Boardman farm, leads to these 
outcrops. This locality is seemingly not so far south as Professor 
Dwight claimed to have traced the Beekmantown; but the writer 
has not been able to add anything definite to the age of this belt to 
the south of this point. 

The Trenton, within this strip, is usually a dark blue rather 
crystalline rock of quite different appearance from the Beekman- 
town. Its lower portion is conglomeratic and carries colonies of 
the coral S. compacta which, without careful examination, 
might be taken for pebbles. This coral, or a conglomerate appear- 
ance, is often the only means for identifying this member of the 
limestone formation. The Trenton is also somewhat finely con- 
glomeratic at times. The conglomerate was noted at Pleasant 


64 NEW YORK STATE MUSEUM 


Valley, at Rochdale and north of the Spackenkill road. The 
Trenton also is probably present in places not yet discovered along 
the eastern margin of this strip. At Rochdale the dark blue Trenton 
beds have a thickness apparently between 60 and 100 feet and form 
a conspicuous stratum. 

Strikes and dips within this strip show much uniformity. In the 
Poughkeepsie and Eastern Railroad cut at Pleasant Valley the Tren- 
ton beds show a strike about n. 37° e. and a southeast dip. In the 
quarry on the Pleasant Valley road to the west of Rochdale the sup- 
posedly Potsdam beds strike n. 42° e. and dip 60° to the southeast ; 
at Rochdale in the road near the mill site, the strike is n. 40° e. and 
the dip 55° southeast; at the conglomerate ledge on the Titus place 
approximately n. 43° e. and 58° s.e.; at the eastern margin east 
of Tompkins’s n. 28° e. and 35° southeast; north of the Spacken- 
kill road in the woods near the old barn n. 53° e. and 42° s.e.; at 
the New Hamburg tunnel about n. 60° e. and 30° s.e. 

Structural features. The presence of an erosion interval 
between the Trenton beds and the Beekmantown is conclusively 
shown by the relationships at Rochdale. The Beekmantown is 
separated from the Trenton by a heavy conglomeratic layer, and the 
fauna and lithologic character of the two strata are markedly dif- 
ferent. The general uniformity of dip shows a “ deceptive uncon- 
formity’’ or “disconformity.”+ From the apparent thickness of 
the Beekmantown at Rochdale, it would seem that this formation 
was not extensively eroded here. 

The limestones of this central strip rest against the slates on the 
west by overthrust. This is best shown at the north end of the 
New Hamburg tunnel (see plate 9). The occurrences of the 
Potsdam along this western margin is also evidence of it. Fre- 
quent slips along and across the strike within the limestone are 
probably present. 

The slates along the eastern margin of the strip may be at places 
in conformable relationship with the limestone. In other cases such 
is almost certainly not the case. 

Metamorphism and alteration. The strata composing this 
strip are all visibly altered. Fossils have usually been greatly 
obscured. The Beekmantown shows the metamorphism most. 
Fossils in it are recognized or identified usually with difficulty 
although they sometimes weather out with distinctness. The Tren- 
ton beds are usually somewhat crystalline, but fossils are preserved 
in them in better condition than in the Beekmantown. , _ 


1 Professor A. W. Grabau. Science, n. s., 22:534. 


jeuuny Sinqure py MON I9Y4} FO pus UIOYILOU IY} Je SoJRIS IY} UO JSNAYJIOAO SOUOJSIWIT 


GEOLOGY OF THE POUGHKEEPSIE QUADRANGLE 65 


Summary and conclusion. The absence of the Trenton con- 

glomerate at places along the eastern margin of the central strip 
‘might be interpreted as the result of faulting and, in any event, is 
probably due in part, at least, to faulting. 
_ The presence of Tetradium cellulosum in the Pough- 
‘keepsie and Eastern Railroad cut at Pleasant Valley is noteworthy. 
Professor Clarke’ has indicated that elsewhere this fossil is charac- 
teristic of the Lowville. The Trenton conglomerate at this locality 
is apparently a few feet above the beds carrying this fossil. This 
would seem to indicate that the Lowville might have been deposited 
here. Doctor Ruedemann? has discussed the Trenton, as descrbed 
by Dwight, as probably not lower than Midtrenton in age. 

The examination of this strip leaves one in great doubt as to how 
‘to represent its structure. It is certainly very different from Pro- 
fessor Dana’s early representation as a simple fold.* It is best inter- 
preted as belonging to the same thrust that pushed the western 
‘strip on the slates, but as the map shows the limestone broke both 
along and across the strike and at the south was pushed farther 
west, apparently feeling the influence of the Highlands mass. 


“MISCELLANEOUS FAULTED BLOCKS OF THE WAPPINGER CREEK BELT 


Several smaller limestone masses, each of which can be reason- 
ably shown to be a detached and separate block, forming an inlier 
in the slates, are scattered to the east of the central strip along its 
middle portion. The mantle of the surface deposits at times 
greatly obscures their exact relationships to the slates, but as a rule 
the field relations leave scarcely any doubt of their inlying character. 
‘In most, if not all cases, these relations point to faulting, both 
‘along and across the strike between the limestone masses and the 
‘slates which surround them. 
_ These blocks will be described separately and will be designated 
by numbers from north to south. The occurrence of these faulted 
blocks of limestone to the east of the central strip seems to be 
directly due to the thrust which carried the limestone of this belt 
over the slates. They have been left, stranded as it were, behind 
the main mass. 


1 Guide to the Fossiliferous Rocks of New York State. N. Y. State Mus. 
Handbook 15, p. 9. 

2Hudson River Beds near Albany and their Taxonomic Equivalents. 
N. Y. State Mus. Bul. 42, 1901, p. 501. 

SAmer. Jour. Sci., May, 1879. 17 :382. 


66 NEW YORK STATE MUSEUM 


Faulted block number 1. This block of limestone, which is 
the most northerly of these masses, lies about a mile north of Man- : 
chester Bridge on the farms of A. W. Sleight and George Byer. 
Its apparent northern boundary is along a northwest-southeast line 
that crosses the Sleight farm just north of the barn and inter- 
sects the roads to Pleasant Valley and to Overlook. About 75 
yards south of the Overlook road, where this makes its first turn in 
ascending the hill, the visible northeastern boundary of the lime- 
stone is marked by a ledge. Its eastern boundary extends south 
from here for about one-fourth of a mile. At the southeast the 
limestone is represented by impure shaly limestone. At a point 
just north of the wall between the Byer farm and Hart’s orchard, 
tue slate outcrops and continues to outcrop to the south for a mile 
or more. ‘The slates are in close proximity to the limestone in 
many places along the eastern border. Just south of the sheep pen 
they form a scarp between which and the limestone the farm road 
descends. The road is, however, apparently on the limestone. The 
limestone outcrops just south of the farm road at the base of the 
hill and continues as a steep scarp just within the woods northward 
from this point for several hundred yards and then turns west and 
crosses the road and ends in a large ledge 50 feet west of the road. 
North from here it is finally lost under drift, but is readily fol- 
lowed along the road toward Sleight’s house. There are no out- 
crops of any kind between Byer’s house and barns, which stand on 
a knoll of limestone, and the steep scarp 200 yards east of the road. 
Ledges of limestone probably determined the terrace slope just 
west of Sleight’s house. Drift conceals outcrops north of Sleight’s 
barns. Quartzitic rock of the slate formation outcrops between the 
Pleasant Valley and Overlook roads 100 feet north of the latter. 
Between here and the outcrop of limestone marking the northeast 
corner of the block there are no outcrops. Presumably the lime- 
stone, in part at least, underlies the flat terrace level just east of 
Byer’s house. 

On the eastern margin of this block, partly on the property of 
A. W. Sleight and partly on that of George Byer, is an old quarry, 
which many years ago furnished stone for the abutments of the 
bridge at Manchester. The fact that this is a rich fossil locality 
appears up to this time to have escaped attention. 

There are two varieties of rock in the quarry. The one which was 
quarried chiefly and which makes up most of the quarry is a dark 
blue rock which varies in texture from a fine calcareous con- 


A portion of the wall in A. W. Sleight’s quarry. In the foreground Trenton con- 
glomerate withS olenoporacompacta resting on probable “ Calciferous ” 
which is exposed in the upper half of the picture. The two are disconformable, 
but have the same dip to the southeast 


GEOLOGY OF THE POUGHKEEPSIE QUADRANGLE 67 


elomerate, shown at the south end and in the central part of the 
quarry, to a dense fine-grained mud rock at the northern part. The 
‘bedding surfaces are distinct, and good-sized blocks, frequently a 
foot or more in thickness, have been removed. The rock has been 
weakened by blasting. It still breaks with difficulty into thin irregu- 
Jar pieces that are often crowded with fossils and their fragments. 
The removal of the mud rock at the south end of the quarry has 
exposed the basal conglomeratic portion which contains abundant 
crinoid stems, colonies of Solenopora compacta and some 
‘brachiopods. The quarry faces east. The beds of limestone strike 
on. 40° e. and dip 42° s.e. At the top of the quarry, under the bank 
and at the summit of the ridge the rock changes to a chamois or 
gray color but retains the same strike and dip. 

_ About seven or eight feet in thickness have been preserved of the 
finer-textured blue mud rock at the north end of the quarry. 
Fossils are distributed through it, but could be removed in numbers 
only from the surface layers. The rock has yielded: 


to} 


Memaraticlia testudinaria 2 20....5.-..08.- ERATE Ee Ae a 
Seeeomenaraitcimate 67... Se uy Sa ek. ies I 
Es Tipvens, U0 ae ee a aera ae aT 3 
'Streptelasma Sper (cesemi Dit om pat Vlad) haere se chs. ote oe Bae 2 
REPS MyCO MERC OINN aye haces. ead ee eee ee es ee 3 
Ceraurus Plemnexantmemuse (probably). Aas: crak fee e' x 
_ Platynotus trentonensis (prcbably) ......... PARE SE ote eure a aN I 
RPMRMIII CHS SOMATA. el. tee ae gfe) e ated se a Sa ale ASHE 2h: 6 
SE ees (puOpably elf! Meee es Wil. ek 
Miilaents crassicauda (probably) ...........0....000.000000- I 
Mueercod undetermined ol... S22). aah. ae eee ee ee I 


At the western base of the ridge, somewhat to the southwest of 
‘this quarry, and now completely hidden by thick underbrush within 
the edge of the woods, is another and older quarry from which it 
“appears the rock was removed and burned for lime a good many 
years ago. Solenopora compacta was noted here. 

The width of the dark blue limestone stratum on the east is prob- 
ably less than a score of feet. A small diagonal fault crosses the 
4 limestone just west of the road that ascends to the sheep pens. 
; The blue rock of the quarry is the same as that at Pleasant Valley 
and Rochdale. The chamois-colored or gray rock is assumed to be 
the Beekmantown (as qualified above). : 


3 
4 


68 NEW YORK STATE MUSEUM 


The presence of the Trenton along the western scarp, as marked 
by S. compacta, accompanied as it is by a scarp, suggests 
that it probably is faulted in here. 

Faulted block number 2. Whether this block is distinct from 
number 1 might be a matter of interpretation. ‘The house and 
barns of George Byer are built on the summit of the western scarp 
of this block which, west of the house, descends abruptly to the 
level of the present flood plain of the creek. The northern margin 
ends 100 yards north of the barn. The most eastern outcrop at the 
north is separated from the ledge, marking the visible western 
margin of block number 1 by a shallow gully. The two may unite 
below the surface. At the south the limestone is lost under the 
terrace, but it is assumed to continue south for a distance. The 
slates do not outcrop between its western scarp and Wappinger 
creek, but as the slates extend well up in this space in the bed of 
Wappinger creek and west of it they almost certainly underlie the 
interval where outcrops are concealed. The block is regarded as a 
dismembered part of the central strip. The slates have been 
dropped down between the latter and these two blocks at the east. 

Faulted block number 3. The evidence for the presence of the 
limestone at this point consists of two small detached ledges appar- 
ently in place, and a scarplike topography. The lew hill shown on 
the map at this place was approached through the fields south of 
Manchester Bridge station. The northern slope of the hill is made 
up of drift, but along the wooded western slope a careful examina- 
‘tion disclosed a small ledge of conglomeratic rock with a strike of 
n. 5° w. and a dip of 32° e. The base of the slope is marked 
by aswamp. A few hundred feet to the southeast is another ledge- 
like mass of the limestone with nearly the same strike. North near 
the railroad and east and west outside the cover of the drift and in 
the fields at the south are low-lying ledges of slate. 

Faulted block number 4. The visible northern termination of 
this block is on the farm of Mr Rothenburg at Titusville. The 
limestone forms a conspicuous ledge just southeast of the barn. Its 
eastern margin may be followed southward as a low scarp across 
the road where the limestone abruptly disappears under the low- 
land along Wappinger creek. In places along the eastern margin, 
and well shown in two ledges just southeast of Rothenburg’s house, 
the apparent dip is about 55° w. and the strike about n. 44° e. and the 
rock appears somewhat thin-bedded. The western margin is indis- 
tinct. The limestone outcrops just under the road bank, where the 
road turns east, and rests against the slates in the bed of the brook. 


GEOLOGY OF THE POUGHKEEPSIE QUADRANGLE 69 


On the north side of the road near the turn is an old quarry. No 
fossils were found, but the quarry rock resembles the dark blue 
mud rock of the Trenton. 

Faulted block number 5. Between this block and number 4 
is an interval of lowland forming the present flood plain of Wap- 
pinger creek. This interval is probably underlain by the slate which 
was dropped down in here and which, in connection with faulting, 
produced a line of weakness which the base-leveling forces early 
reduced and which has been perpetuated by the present stream. 
Outcrops are concealed in the flood plain interval except near the 
southwest corner of block number 4. At this point there is a large 
patch of slate that has been planed down and which disappears 
under the alluvium at the southeast. 

The rather steep slope on the southwest side of this interval is 
taken as representing the northern margin of block number 5. The 
eastern and western margins are approximately those shown on the 
map, while the southern margin appears to be along the great fault 
line at this point. Surface deposits conceal the northern margin, 
but outcrops are occasional to the north of the Poughkeepsie-New 
Hackensack road, and almost continuous along it from east to west. 
The western margin is easily followed along the crossroad to the 
Spackenkill road until the limestone is cut off by the fault. No 
fossils were found in this patch of limestone and the lithology did 
not help in making any provisional correlation with other localities. 

Faulted block number 6. This small strip lies south of the 
Spackenkill road and is a little over a mile long and less than one- 
fourth of a mile wide. It is separated from the main central strip 
Dy a narrow band of the slates which form conspicuous ledges for 
a few hundred yards south of the Spackenkill road and are trace- 
able along the edge of the swamp through the woods to the southern 
termination. At the south the limestone disappears abruptly 
beneath the slates just north of the old barn and probably is faulted 
here. At the north it also gives place to the slates north of the 
Spackenkill road and is certainly faulted here. The limestone of 
this strip forms-a conspicuous ridge throughout its length. No 
fossils were found although a careful search was made, particu- 
larly near the southern extremity. 

_ Faulted block number 7. This block lies farthest east of all. 
The boundaries are best indicated by the map. The entire strip has 
a northeast-southwest bearing which closely follows the general 
strike of the limestone. It is about one and one-fourth miles long 
and one-fourth of a mile wide. At the north it disappears beneath 


7O NEW YORK STATE MUSEUM 


the low ground along the railroad and gives way at the north to 
slates, although some distance intervenes between outcrops. The 
northern margin is plainly a faulted one and lies along the very 
prominent but narrow valley that forms the route of the Central 
New England Railroad track almost the entire distance from Hope- 
well Junction to Manchester Bridge. That this represents a line of 
faulting is reasonably certain. As a topographic feature it may be 
followed across country for miles. It is often swampy, frequently 
for long distances, and this feature was probably still more prom- 
inent before the railroad bed was put in. It does not have the 
appearance of having been a prominent line of drainage, but rather 
a more extensive illustration of the topographic effect of base-level- 
ing forces operating along a continuous line of weakness such as a 
great fault would produce. There are other conspicuous illustra- 
tions of the same kind, both within the slates and limestones of this 
quadrangle. 

The southern margin is obscured by a great mass of drift, but the 
limestone is almost certainly cut by a fault on the southwest. 

A mile and a half north of New Hackensack a crossroad con- 
nects the New Hackensack road with another running for some 
distance parallel with the railroad track. The northwestern margin 
may be followed from this road northeastward to the railroad track, 
outcrops appearing between the latter and the road just south of it 
Along this margin the limestone shows a low scarp tor some dis- 
tance. The eastern margin is also easily followed as a scarp trom 
the crossroad where the limestone appears in contact with the 
hlack, splintery slates northeastward to the railroad. Outcrops 
occur along the public road at the north. Everything is concealec 
south of the crossroad at the south. 

The limestone of this block is of a very dark bluish-gray color 
It often shows veinlets and nests of calcite. Fresh surfaces show 
darker and more crystalline bunches in a rock of dark gray color 
The rock is more crystalline than other members of the Wappinget 
creek belt. In lithology, it often has a strong resemblance t& 
varieties met with in the Fishkill limestone, notably southeast o 
Hopewell. No fossils were found. The average strike is abou 
n. 60° e. and the dip 40° s.e. The block forms a distinct topo 
eraphic feature. 


THE: FISHKILL LIMESTONE 


The belt of which this limestone is a part may be traced witl 
some interruptions from Millerton in the northeastern corner 0 
Dutchess county nearly to the Hudson river. The portion witht 


(deut 99S) IUOJSOLMI] [[IYYShY Poyyney oy} Ur A[[Va IVepNsuvt41} IY} SI adLI[IA 94} FO YON ‘UorTUNL [JomodoT] 
JO ISU][IA oY} St oinjord oY} oO JoJUID 9y} IV9N ‘psleMyYy OU suryoo] ‘uotjouN[ [Jjemodoy] fo YANOs , [IY AouUOg ,, WOT MoIA VY 


woe oe 


GEOLOGY OF THE POUGHKEEPSIE QUADRANGLE WA 


- this quadrangle occurs as a great fault-bounded block north of the 
Fishkill mountains. Northeastward it may be followed up the 
Clove valley, east of which it passes under the mass of schist com- 
_ posing Chestnut ridge and reappears in the Dover-Pawling valley. 
The overlying slate formation has been removed from. this 
. faulted limestone mass within this quadrangle, which makes it con- 
_ yenient to discuss the mass as a unit. 
_ Boundaries. The northern boundary enters the quadrangle 
Rico the town of Beekman and extends southwestward along the 
old roadbed of the Clove branch of the Newburgh, Dutchess and 
' Connecticut Railroad to a point about one mile east of old Hopewell, 
where it intersects a northwest-southeast fault and turns with a 
sharp angle to the northwest. The actual contact of limestone and 
t slate usually can not be seen, but the field relations and obvious fault 
features approximately determine the course of the boundary. 
Somewhere south of Arthursburg, the actual point being concealed, 
~the boundary again turns abruptly, this time to the southwest, as 
= on the map, and follows the valley of the Whortlekill to a 
"point just west of Hopewell Junction, and then turns to the north- 
west to follow the fault previously referred to, along the raliroad. 
- Three- fourths of a mile west of here a ledge of shaly limestone 
“t “marks the northwest limit of the limestone along this fault line. 
: “The slates extend down into the included angles of these fault lines, 
: as shown on the map. Southwest from the ledge of shaly limestone 
just mentioned the boundary is easily followed across the fields, 
often with a clear scarp or other distinct topographic feature, and 
with slate and limestone frequently in close proximity, to the fault 
Bhat bounds Vly mountain on the east; then north along this 
“fault, with the slates again in the included angle, to Vly mountain, 
which is bounded by the limestone on the south. Southwest of Vly 
“mountain the limestone bounds the Glenham belt to the carpet muiil 
-at Glenham. South of here it is faulted against the slates for half 
a mile, then rests against the gneiss of the northernmost inlier in 
the town of Matteawan, then on the quartzite patch just south of 
, this, and again on the gneiss. 
: Its southern margin has been described sufficiently in connection 
4 with the gneisses and the quartzite. 
_  Terranes present. The fossil localities so far discovered in 
_ this limestone are limited in number and in distribution. The Lower 
~Cambric (Georgian), Beekmantown and ‘Trenton have been 
definitely identified. In the systematic and extensive examination 
of outcrops in cuts and weathered surfaces, suggestive markings 


“¢ 
=o, 
. 
ny 
a 
5 


Sh wc 


cs 


72 NEW YORK STATE MUSEUM 


have been noted and collected at several places. Increasing meta- 
morphism to the eastward has destroyed or otherwise effaced traces 
of organic remains, besides making very difficult any provisional 
correlation on the basis of lithological resemblance. Folding, fault- 
ing and erosion have added great confusion. 

The Lower Cambric (Georgian). Strata belonging to this 
horizon have been described under the heading, “ The conformable 
series of West Fishkill Hook (see page 44). The reasons for 
their pieservation here are not quite clear, but evidently the condi- 
tions are peculiar. As previously discussed, it seems probable that 
the Lower Cambric limestone is, as a rule, not in association with 
the quartzite of that epoch which more probably rests against 
younger strata at most places. The patches of limestone resting 
upon the quartzite at Vly mountain and in Matteawan may be of 
the same age. Some peculiar, very thinly-bedded metamorphosed 
strata, which were noted standing on end in the swampy areas east 
of Mount Honness, may represent the shaly member of the Lower 
Cambric series and these Lower Cambric rocks may have an exten- 
sion to the north from here in certain rock types that will be 
described beyond. 

The Beekmantown. Fossils belonging to this horizon were 
found along the western margin of the Fishkill limestone. They 
were first noted north of the road from Fishkill Village to Glenham 
on the farm of Albert Haight, in the second field west of Haight’s 
house, about 300 or 400 yards from the public road. The rock 
carrying the fossils is of a light gray or steel-gray color and is 
interbedded with other rock which weathers to a soiled gray. The 
weathered surface of the former shows many spiral coils. The 
fresh surface reveals a much altered rock. No traces of the whorls, 
so plainly visible on the weathered rock, can be seen on the freshly- 
broken surface; but the latter is often dotted or splotched with 
numerous orange or pollen-yellow markings. 

In this field there are two conspicuous ledges of the fossiliferous 
stratum besides many outcrops of other ledges, for the most part 
‘soil-covered. In the northwest corner of the next field to the north 
on Haight’s farm is another ledge of the light gray rock covered 
with the coiled markings. This stratum was traced by scattered 
outcrops carrying the coils along and within the edge of the woods 
and thick brush for a mile to the northeast, to within about half a 
mile of the road from Fishkill Village to Glenham, and then was 
lost. Beyond this road it has not been noted, unless it may be 


Plate 12 


Fossiliferous ledges on the farm of Albert Haight, between Fishkill Village 
and Glenham. The surface marked by the hammer is covered with the whorls 
of Ophileta compacta, some of which are visible in the plate 


‘ 


GEOLOGY OF THE POUGHKEEPSIE QUADRANGLE 73 


represented by a somewhat banded bluish rock without visible 
fossils which was found on the very edge of the limestone about 
four miles to the northeast at Swartoutville, a hamlet two and one- 
half miles north .of Brinckerhoff. On the Haight farm the fossil- 
iferous limestone is well exposed in the fields, but in the brush it is 
followed with great difficulty. This rock, or that with which it is 
interbedded, is overlain by a calcareous conglomerate in certain 
places. 

The fossiliferous limestone is very dense and compact. It is 
quite impossible to remove the coils from the smooth surface. A 
hard blow with the sledge simply chips the rock into small pieces 
with conchoidal fracture. The chisel makes no impression. 

The coils are most distinct when at right angles, or nearly so, to 
the axis of the whorls. They then show as fine spiral lines, 
resembling a fine loosely-coiled watch spring, which have weathered 
out very sharply into bas-reliefs. When in the plane of the axis, or 
at a small angle with it, the lines are thick and patchy. The fine 

coils vary in diameter from one and one-half inches to three-fourths 


ee 


‘Fig. 22 Whorls of a discoidal gastropod identified as Ophileta compacta Salter, from the 
M ledge shown in plate 12 
of an inch. The medium-sized are most abundant. They bear the 
Closest resemblance to the discoidal gastropod Ophileta 
compacta Salter, as described for the Calciferous of the 
_ Quebec group’ (see plate 12). 


1 Canadian Organic Remains, 1859. Decade 1, p. 16, plate 3. 


74 NEW YORK STATE MUSEUM 


The smaller coils resemble the Maclurea sordida and 
Ophileta levata of the Calciferous of New once ee 
form, which very closely resembles the Oplirl@tagieamin 
planata as figured by Hall,? was noted. 

The fossiliferous rock at Haight’s farm lies just east of the Glen- 
ham gneiss belt with outcrops of the latter not more than 150 or 
200 feet away. The strike of the limestone varies from n. 15° w. 
to ns. and the dip from 35° to 40° e. The strike is such as to 
carry the limestone diagonally across the gneiss belt. The distance 
separating the gneiss is too short to allow a very great thickness of 
older beds to come between the two. South of the fossiliferous 
ledges in the quarry used by the State road contractors on the farm 
of Mr Wilsey, are thick-bedded arenaceous limestones with a strike 
of n. 35° e. and a dip of 51° s.e. These are probably older beds. 

East of the ledges of Beekmantown outcropping along the Glen- 
ham belt, this horizon has not been definitely identified. In the 
town of Old Hopewell, just east of Fishkill creek, is a prominent 
hill which has some beds strongly suggesting the blue beds inter- 
stratified with the gray ones in the main strip of the Wappinger 
creek belt at Rochdale and two or three miles south of that hamlet. 
The two rocks look very like each other and the resemblance is 
strengthened by the presence of the peculiar seaweed-like markings 
which have been described. The rock at Hopewell is more meta- 
morphosed. Along the track of the Highland division of the New 
York, New Haven & Hartford Railroad, in the cut three-fourths 
of a mile east of the railroad bridge crossing the creek east of Hope- 
well Junction, these blue layers form the upper portion of a gentle, 
northward-pitching anticlinal fold (see plate 13). A distinct fault 
is seen just east of here crossing the track and, when traced north- 
‘ward, this is seen to be in line with the recess shown on the map just 
south of the point where the creek turns northward in making its 
detour around the hill. East of this northward bend the creek has 
cut a gorge in the limestone, having been deflected southward by a 
great mass of glacial deposits that flanks the limestone: knoll north 
of Gregory’s mill. On the weathered surface of this knoll a fossil, 
which looked like a cephalopod, was found. 

This rock resembles the blue layer just described. It often shows 
a banded character which recalls the banded marbles or crystalline 
limestones seen in the quarry two miles southwest of Millerton. 


1 Palaeontology of New York. 1:10-11, plate 3. 
2 loc. cit., p. 11, plate 3. 


GEOLOGY OF THE POUGHKEEPSIE QUADRANGLE WS 


Presumably the beds with which the bluish beds are interstratified 
belong with them and the-Beekmantown may be fairly well repre- 
sented. Elsewhere it has not proved possible to make any corre- 
lation even of a provisional character with this horizon. 

The Trenton. The presence of this horizon within the Fish- 
_ kill limestone was first indicated on the basis of fossils by Professor 
J. D. Dana.t. He described the white fine-grained and gray lime- 
stones north and east of Shenandoah and announced the discovery 
in the gray rock “one-third of a mile north of Shenandoah Cor- 
mets Ot large shells of a Strophomena like S. alternata, 
distinct in form though disguised by pressure and slight alteration, 
indicating for the beds a Trenton age.” He also noted suggestive 
forms and markings between Hopewell and Fishkill,? but nothing 
of distinctive value was obtained. . 

This horizon, as known from the Wappinger belt, was definitely 
identified by the writer along the western margin of this limestone 
‘in close association with the beds carrying Ophileta com = 
pacta. Inthe second field northwest of the barn on the farm of 
Albert Haight, on the road from Fishkill Village to Glenham, a 
ledge of coarse conglomerate lies just south of the ledge showing 
mie ©. compacta. A few yards east of-the latter ledge a 
finer conglomerate carrying Solenopora compacta was 
discovered. The latter is almost covered with soil and this rock 1s 
exposed in only a few places. The conglomerate was also followed 
along the edge of the wood in a series of low-lying knolls for some 
distance. About half a mile northeast of these ledges, about 350 
yards northeast of the Southard house, and the same distance north 
_ of the public road, near the edge of the woods, at the point where 
an old wood road leaves the woods, the light grayish-colored rock 
passes into a thin layer of fine conglomerate of the same color and 
then abruptly into a dark blue fine-grained conglomerate. The ledge 
showing this transition is in place, but is very narrow and lies nearly 
flat, dipping at a very slight angle to the southeast. A hundred feet 
northeast of this ledge, beyond a stone wall, the coarse conglomerate 
outcrops. What appeared to be brecciated conglomerate was noted 
in one or two ledges farther north. 

There is thus a narrow, but well defined, strip of the Trenton 
conglomerate along the western margin of this limestone. Its for- 
mer eastward extension is wholly problematical. 


Amer Jour Sct Ser. 3) Dee 1880. 20:452. 
Amer. Jour. Ser. . Ser. 3. May, 1870. 173383. 


76 NEW YORK STATE MUSEUM 


At Swartoutville, a little hamlet about half way between Brincker- 
hoff and Hopewell Junction, on the farm of Irving Hitchcock, a 
calcareous conglomerate, with the pebbles squeezed into bands, out- 
crops in places between the bluish-gray limestone, referred to above 
as possibly representing the Beekmantown, and the calcareous shales 
with interbedded limestone layers, the iatter lying on the west along 
the margin of the limestone. In other places the shales with their 
interbedded limestones grade downward into a fine conglomerate 
with what looked like S. compacta and other fossils. 

During the spring of 1909 a number of new cuts were made in 
the limestones along the road from Johnsville to Stormville in the 
process of constructing the State road. In one of these, about two 
miles east of Johnsville, a fairly distinct impression was found. 
This may be a fossil. The general form is apparently preserved, 
but the details are obliterated. Other blackened and much more 
distorted impressions were noted. These impressions, together with 
other markings, such as bunches of calcite crystals, mark the rock 
as probably fossiliferous. 

Some peculiar lithic variations within the Fishkill limestone. 
Northeast of Johnsville, on the farms of Messrs Gildersleeve and 
Taylor, are frequent outcrops of a coarse silicious limestone, which 
was not noted elsewhere in this limestone belt. It somewhat 
resembles the basal quartzite at times. It is always calcareous, 
effervescing readily with cold dilute acid, but leaving a prominent 
residue cf quartz. It is interbedded with other limestones, which in 
their lithological characters recall the chamois-colored beds in the 
Beekmantown of the Wappinger creek belt. The silicious rock 
just referred to outcrops along the road south of Bonney hill north 
of Taylor’s house, while Bonney hill seems to be largely made up of 
the medium-bedded chamois-colored rock, except at the west along 
the lower portion of the scarp slope, where it gives place to a gray 
limestone. No fossils were discovered in these limestones. It is 
noteworthy that they lie close to the northward continuation of une 
strike of the rocks in the West Fishkill Hook district. 

A diligent search was made within this limestone east of the 
western margin for a conglomeratic layer, but none was found. 
What appear to be coarse brecciated zones are of frequent occur- 
rence, particularly west of the Honness spur. These were noted 
just southeast of Milton C. Hustis’s house at Brinckerhoff, between 
Mount Honness and Fishkill creek, where the rock is mashed, and 
in the Newburgh, Dutchess & Connecticut Railroad cuts between 
Fishkill Village and Brinckerhoff, and less noticeably but plainly 


GEOLOGY OF THE POUGHKEEPSIE QUADRANGLE WU 


elsewhere to the north toward Hopewell Junction and east toward 
Stormville. The discussion of the structural features will bring out 
the fact that there must have been a strong tendency toward crushing 
and mashing along the limbs of minor folds within this formation. 

In the woods west of Wood’s greenhouses at Fishkill Village are 
numerous outcrops of a very fine-grained metamorphosed rock 
which suggests an altered silicious ooze. It was noted in several 
places within short distances of each other and not far from ledges 
carrying Ophileta compacta. It appears to be a rather 
abrupt variation of the rock with which it is associated, and prob- 
ably is to be regarded as a variation of the Beekmantown. 

Certain varieties are plainly the products of metamorphism and 
will be referred to again under that heading. 

In most cases, the lithology of the Fishkill limestones does not 
convey anything definite of which one may make use for provisional 
correlation. In the new cuts along the road from Brinckerhoff to 
Stormville even the fresh surfaces convey very little. In some of 
the ledges near Gayhead* the fresh surface carries numerous rusty 
patches, possibly siderite, witch recall some surfaces seen in the 
quarry at Stoneco. 

The magnesian character of some of these limestones is well 
known. ‘There is some reason for thinking that they were accumu- 
lated in somewhat restricted bodies of water. Possibly they are 
partly the products of precipitation from saturated solutions. 

If during the time these deposits were accumulating there were 
several basins more or less completely cut off from each other, it 
is easy to understand that there would have been some diversity in 
_ the condition of sedimentation in this region. In some places there 
would have been normal marine conditions with characteristic 
animal forms, while in others, perhaps, there would have been an 
accumulation of sediments peculiar to basins more or less com- 
pletely cut off from the sea with an absence of animal forms. An 
influx of the sea in these restricted basins would carry with it a 
change in sediments and a marine fauna and a fossiliferous lens 

might thus be produced within a barren dolomite. 

The absence of the conglomerate and overlying formations over 
most of the Fishkill limestone indicates that it is composed chiefly 
of older strata, probably ranging discontinuously from Lower 
Cambric to Beekmantown. As the folds in the limestones are 


1 Fast Fishkill is invariably referred to as “ Gayhead,” in this region. The 
name seems to have originated from the head adornments of the ladies who 
flocked to this place for dance festivals in early years. 


78 NEW YORK STATE MUSEUM 


moderate swells the older masses have not been exposed, except 
where faulted. Much of the surface rock may be of Beekmantown 
or Upper Cambric age, the latter belonging to the upper dolomitic 
layers of the sediments of that epoch. 

Structural features. The hiatus that is present between the 
Beekmantown and the Trenton within the Wappinger creek belt has 
its counterpart along the western margin of this limestone; but the 
failure to find any conglomerate farther east, such as usually repre- 
sents the base of the Trenton, not only in the Wappinger creek belt 
and along the western margin, but also in the slates at the north, 
leaves much uncertainty as to the relative stratigraphic position of 
much of this Fishkill limestone. The presence of certain faults adds 
to the perplexity ; while the general faulted position of the Fishkill 
limestone as a whole and the absence of the slates within it rather 
leaves the impression that it is made up chiefly of limestones older 
than the Trenton conglomerate, except where younger beds have 
been faulted in. 

in spite of faults and thrusts the general folded arrangement of 
the Fishkill limestones can in some instances be made out with a 
fair degree of exactmess. 

In the hamlet of Wolcottville the limestone is in contact with the 
gneiss. In'the town of Matteawan it first rests against the slates, 
which are almost certainly younger, and then on the gneiss, then on 
the quartzite and finally on the gneiss again. The quartzite contact 
may be normal. The gneiss contact may also be normal in places, 
but in such cases the gneiss is presumably the equivalent of the 
basal quartzite and represents an altered condition of the gneiss. 

The fault on the west of the Glenham belt represents an early 
thrust which was succeeded and outstripped by the Bald hill thrust. 
The western break also bounds the Matteawan inliers at the west. 
Faults bound the Glenham belt on the south and the northern inlier 
of Matteawan on the north and between these the slates have 
apparently been dropped. 

Numerous breaks may occur in Matteawan so that the limestone 
resting on the quartzite in that town may not be of the same age as 
that which rests against the slates. The limestone is traceable to the 
north across Fishkill creek and through Glenham and beyond. But 
as a rule not much can be made out about the structure. 

At Wilsey’s quarry on the Vishkill-Glenham road the arenaceous 
limestone strikes n. 35° e. and dips about 51° s.e. In the field just 
north the fossiliferous Beekmantown and interbedded limestones 
have a strike varying from n. 15° w. ton. s. and a dip of 35° e. One- 


GEOLOGY OF THE POUGHKEEPSIE QUADRANGLE 79 


half mile to the northeast the dip is gently away from the gneiss 
and the strike cuts across it at a small angle. This general relation 
holds to the Chelsea read. 

The topography southeast of Fishkill Village is very flat. There 
are few outcrops north of the Fishkill-Glenham road, between it 
and the woods, until the farm of Albert Haight is reached and none 
to the south of it until Glenham is reached. Low ledges of lime- 
stone appear north of Fishkill Village. Between the Chelsea and 
Wappinger Falls roads and north of that road and the Cold Spring 
turnpike they are abundant. 

Just north of the village on the west side of the road, to the ~ 
south of the cemetery, the strike is n. 55° e. and the dip 35° s.e. 
(lettered B in section figure 23). Farther north on the roadside 
near the gneiss the strike is n. 15° e. and the dip 49° n.w. (lettered 
A). At the railroad crossing on the Cold Spring road the strike is 
n. 80° e. and the dip 46° n.w. (lettered C). Southeast of Fishkill 
creek and northeast of the Cold Spring road, from a point a short 
distance from the road as far as Milton Hustis’s farm, the strike 
varies from 25° to 40° east of north and the dip is toward the 
mountain and according to readings taken varies from about 50° to 
62° s. e. (lettered D). Along the road from Fishkill Village to 
Brinckerhoff, about one-half mile from Main street in Fishkill 
Village, the strike and dip are about the same as at the railroad 
crossing. Along the northwestern margin of the limestone to the 
northeast of the Wappinger Falls read the strike and dip are not eas- 
ily followed. Along a section in a northwest-southeast direction from 
the Glenham belt through Fishkill Village to the northwestern base 
of the Honness spur, as shown on the map and the accompanying 


Fig. 23 Section across the Fishkill limestone along a northwest-southeast line through Fishkill 
Village rom the Genham gneiss to the Mount Honness spur, to show the character of the folds 
Distance 2 miles 


section (fif. 23), the limestone is in a series of northwest-south- 
west folds which have suffered great erosion and, at places, much 
disturbance. The latter is shown along the highway and in the rail- 
road cuts southwest of Brinckerhoff, where the strike is only at a 
small angle to the east of north and at one place n. 50° w. with east- 
erly dip. Northeast of Brinckerhoff the strike and dip return to the 
former general direction. In the railroad cut just north of the Johns- 


So NEW YORK STATE MUSEUM 


ville road they are n. 30° e. and about 43° s.e., and one mile south of 
Hopewell Junction n. 44° e. and 45° s.e. 

The western slope of Bonney hill has the appearance of a fault 
scarp and shows numerous outcrops of limestones dipping to the 
east. Along the road leading south from Bonney hill, at the north 
to the east of the road and at the south to the west of it is another 
scarp with easterly dips. South of Bonney hill a northeast-south- 
west break apparently intersects this fault and the limestones north 
of Johnsville lie in the angle between them. 

The section (fig. 24) along the railroad cut east of Hopewell 
Junction shows some structural detail. Heavy erosion has obscured 
the larger features and has brought out the minor ones. Beginning 
at the west, the section is first through beds dipping gently eastward, 


POEs — 
tf) LPI 


ROS 
SS a ARE OSS : 
BN 0 ie ae ae 


Fig. 24 Generalized section of the south wall of the railroad cut east of Hopewell Junction 


and apparently bordered on the west by the northward continuation 
of the fault that follows the road southeast of Bonney hill. East 
of this it is through a symmetrical northward pitching anticlinal 
shown in plate 13, and complemental synclinal, then in a smaller 
anticline and syncline, and then through an irregular fold with its 
eastern limb pushed up. This is followed by a closely compressed 
syncline which is succeeded by a closely-folded overturned anticline 
(see plates 14 and 15) ; then two small folds which are cut off at the 
east by the fault shown on the map. 

East from here along the railroad the sections are fragmentary. 
In the second cut east of the overhead bridge on the road from Gay- 
head to Gregory’s mill, the limestones show an arrangement like 
that of figure 25. Just west of Stormville station the beds are 


isoclinal, dipping to the east, and show a considerable aggregate 
thickness. 


esa 
ST 
Gary, wi 
Ww. ES Oavaey Beye COS TITAS ie 


Fig. 25 Section just east of the overhead bridge on the railroad between Hopewell Junction anc 
Stormville. Q, nest of quartz 


The tendency to arrangement in somewhat gentle folds is shown 
by numerous observations. In some places the dip is east and at 


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GEOLOGY OF THE POUGHKEEPSIE QUADRANGLE SI 


others west. The strike remains practically unchanged for some 
distance in many instances for beds with the same general dip. The 
limestone differs from the slate at the north with its isoclinal 
arrangement over wide intervals. 

The tendency to overthrust, shown in the section along the rail- 
road, probably prevails over the entire area. Strike faults are most 
apparent. The regularity of the strike for long distances seems to 
indicate that horizontal offsetting has not been important. Two 
large breaks along the strike are shown on the map. ‘They are 
shown in the field by long stretches of swampy lowland that may 
be followed for several miles across country. They seem to be the 
northward projection of faults in the Highlands. The presence of 
these large breaks and minor ones complicates the question of the 
age of the limestone. The displacement must have been a large 
one at places as, for example, along the fault line that bounds 
Shenandoah mountain on the east. Possibly beds of very different 
age lie in close proximity. 

Metamorphism and alteration. Were it possible to trace con- 
tinuously from west to east the beds now known to be present along 
the western margin of this limestone, more could be definitely 
determined about gradation in metamorphism to the eastward. 
Examination of the belt has shown that the rock usually displays 
greater crystallinity as one goes eastward. Banded limestones not 
very different from some seen in the Dover valley were noted near 
Gregory’s mill. There is much evidence of crushing. Bunches 
and veinlets of calcite and quartz nests and stringers are abundant. 
These indicate hydrothermal activities. Organic remains have 
doubtless been obliterated by these as well as by crushng, shear- 
ing and pressure. 

Summary. The Fishkill limestone, in its relations to the 
slates, stands essentially as a huge faulted block. ‘Though less 
plainly shown, the same is true of its relations to the Highlands 
mass. This arrangement has produced a northwestward gradation 
by faulted blocks from older to young masses. ‘These considera- 
tions afford further reason for believing that the Highlands owe 
their present elevation to the mountain-making processes that gave 
birth to the Green mountain system and that the younger rocks 
once had an extension much to the south of their present southern 
limit, thus giving an altogether different notion of the early rela- 
tion of the Paleozoic sea to the Precambric land from that which 
the present topography might be assumed to show. 


82 NEW YORK STATE MUSEUM 


The northward projecting spurs of the Highlands indicate a 
tendency to fold with the younger series, but owing to their crystal- 
line condition and high coefficient of elasticity the gneisses broke 
and were thrust up into the younger rocks, in some places carry- 
ing the latter with them, and in others overriding them. The West 
Hook series was apparently first thrust up and then dropped back 
and has thus been preserved. 

The arrangement in echelon of transverse faults along the north- 
western margin of this limestone belt seems to show the influence 
of the gneissic substratum on which it rests. 

The northward pitch of the younger rocks, which is observable 
in places, may be as readily explained as the result of greater 
vertical movement at the south as of original inclination. 

The Mount Honness spur is plainly faulted on the north and 
shows numerous transverse gaps (see plate 2). 

The abnormal position of the Lower Cambric caused much con- 
fusion in early years and led to its assignment to the Potsdam on 
the basis of its apparent stratigraphic position. 

The occurrence of numerous faults in the quadrangle suggests 
that the apparent absence of a Middle Cambric might thus be 
explained. ; 

The evidence now in, although in great need of being supple- 
mented, shows that the limestones of the Fishkill belt are, in part, 
the eastward representatives of those of the Wappinger creek belt. 


THE “HUDSON RIVER” SLATE (GR@Wi 

The term ‘“ Hudson River” is used in this paper for the slates 
of the quadrangle because of the extensive section displayed in 
these rocks along the Hudson river and because the name is both 
widely known and locally followed by those who refer to the mem- 
bers of the slate formation. It is used only as the equivalent of 
other names employed in this paper and entirely without reference 
to the value of the term “Hudson River Group.” 

Distribution and general relations. Members of this formation 
underlie the major part of the quadrangle. At the present time 
there are no representatives of it within the Fishkill mountains or 
the Fishkill limestone of this quadrangle. Northwest of these rock 
masses the Hudson River rocks are the prevailing ones. The lime- 
stones of the Wappinger creek belt ae faulted in with the slates. 
Northwest of this belt the slates entirely conceal the limestones. 
North of the Fishkill limestone block are several small patches of 


2a ioe 


GEOLOGY OF THE POUGHKEEPSIE QUADRANGLE 83 


limestone within the slates which will be described with this forma- 
tion. 

Terranes present. Mather described the members of this 
formation under the headings, “Hudson River Group,” “ Utica 
Slate” and “Trenton Limestone Group.” He wrote of fossils 
being found in the “slates and slaty altered limestones that would 
not be recognized as limestones without close examination.” The 
locality was about one and one-half miles north of Barnegate* and 
the fossils were recognized as belonging to the Trenton limestone. 

In 1878 T. Nelson Dale® discovered fossils in the slates near 
Vassar College and “on the Stormville road between Casper creek 
and the first limestone ridge.’ Mr Henry Booth, of Poughkeepsie, 
and students at the college found other fossils at the ledge near 
the observatory at Vassar. The writer has also found fossils there. 

In company with Mr Booth, Mr Dale discovered other fossils on 
the west of the Hudson opposite Poughkeepsie. This locality is on 
the eastern slope of “ Illinois mountain” southwest of Highland.t — 

The fossils discovered by Dale were identified by Hall as: 
Paani alnanella) testudinaria, Orthis pec- 
Micti@wmunbeptacma  (Criecctambonites) ~serieea, 
mropmomena alternata, Bythotrephis sub - 
modosa, Bellerophon bilobatus and crinoid stems. 
Specimens of the first five named are in the Vassar Institute Museum 
Pebsouchikcepsic and are labeled) Highland N. Y.” ©O. (D*.) 
Beseudinaria and L: (P.) sericea were found on both 
sides of the river. Dale thought these fossils verified Mather’s use 


of the term “Hudson River Group.” Certainly these strata belonged 
to some member of the Trenton period. 


The first three types mentioned have also been reported from 
Marlboro-on-the-Hudson about nine miles north of Newburgh. They 
have also been found in the slates at the northern end of the New 
Hamburg tunnel.’ The writer has found fossils here, including 
See pectinella, in the shales under the bank, back of the 
boathouse. 


1 Geology of the First District. Part IV, p. 360, 300, 307. 

2loc. cit. p. 401. 

2Amer. Jour. Sci. Ser. 3. 17 7256-50. 

4 Directions for reaching this locality were furnished by Mr Henry Booth. 
Take Modena road from Highland south one mile to cemetery, then wood 
road through cemetery to mountain. Fossiliferous ledges occur 150-200 
yards up the mountainside. 

5J. M. Clarke. Guide to the Fossiliferous Rocks of New York State. 
Handbook 15, p. 6. 


84 NEW YORK STATE MUSEUM 


Crinoid stems have also been found at Marlboro. L. (P.) 
sericea and ©. (D.) testudinaria were steundmonm 
both sides of the Hudson as rather abundant and: characteristic. 

The only other fossil locality in the slates which was found by 
the writer, and which appears to be new, is at Swartoutville. At the 
western edge of the large field across the road from the house of 
Irving Hitchcock is a ridge composed of fissile, gray sandy shales 
with interbedded, dense blue impure limestones. 

The shales stand almost vertical, dipping slightly to the west and 
strike diagonally across the ridge, so that in going from south to 
north along the ridge one passes over probably older beds. The 
interbedded limestones are of dark blue color and carry numerous 
traces of organic remains. The fissile shales have yielded Plec- 
tambonites sericeus, and fragments of indeterminable 
fossils. 

Relations are very obscure, but one or two small outcrops of lime- 
stone conglomerate were noted between these strata and the bluish- 
gray limestone a short distance to the east. In their structural 
relationships the fossiliferous shales probably belong with the lime- 
stones and are probably near the base of the slate formation. The 
slates at the west are younger. The amount of displacement -be- 
tween them is wholly problematical. 

In 1883, during the construction of the railroad along the west 
bank of the Hudson, Messrs H. Booth and C. Lown of Pough- 
keepsie discovered graptolites in the newly-made cuts at two locali- 
ties, one two miles south of Highland and the other about one 
mile north, near the place where the icehouses now stand. These 
graptolites were identified by Whitfield as follows [the correct 
names have been added in brackets|: Diplo eimamonenms 
pristis Hall; Climactograptus "bi@ommaipseeeele 
Dichograptus [Dicranograptus] -furcatus ellen 
[Dicellograptus] divaricatus Hall (?); Monograptus 
[Nemagraptus] gracilis Hall; M.  [Didymograptus] 
sagittarius Hall; Diplograptus manreedmeonenia 
[Cryptograptus tricornis]. He considered them as of Utica age. 
A graptolite identified as Graptolithus [Amphigraptus] 
divergens was also reported from the slates one and 
one-half miles north of Poughkeepsie on the east bank of the 
Hudson river. This specimen is in the Vassar Institute Museum at 
Poughkeepsie.. 


GEOLOGY OF THE POUGHKEEPSIE QUADRANGLE 85 


Some of the slates within the quadrangle are shown by these 
discoveries to be younger in age than the so-called Trenton con- 
glomerate of the area. Some may be contemporaneous and prob- 
ably are;\ others are possibly much younger. The relations 
farther north, in Washington county, have shown that the Lower 
Cambric slates have been brought to the surface by faulting, but 
within this area it has not proved possible to determine this. On 
the whole, it does not seem probable. 

The general problem of the slates is postponed until several fea- 
tures have been stated in detail. 

Red slates. Red slates with green bands of varying thickness 
may be traced at intervals diagonally across the quadrangle, along 
the prevailing strike, from Matteawan to the northeastern corner of 
the area. Their regularity of recurrence indicates that an important 
stratum is involved in the folding. The main stratum of these red 
slates as shown in several places has a fairly uniform thickness. 
Thinner red bands have rarely been noted in the more common 
grayish-black members of this formation. 

In the town of Matteawan red slates with green bands form thick 
masses along the banks and bed of Fishkill creek as far as the 
carpet mills at Wolcottville, and north of here at Glenham along 
the road from Matteawan to Fishkill Village, just west of the Glen- 
ham gneiss belt, ledges of these rocks are abundant. ‘The red slates 
are locally called the “ paint rock.” Farther north along the strike 
they were noted north and south of the road from Fishkill Village 
to Chelsea and along the road from Swartoutville to Hughsonville. 
A thick band occurs along the New York Central Railroad track 
one-fifth of a mile south of Paye’s clay pits and a similar band just 
north of the station at Chelsea. They were not noted farther north 
along the river section. The slates at Chelsea continue northeast 
along the strike and appear one mile north of New Hackensack 
along Wappinger creek, and again near Manchester Bridge and at 
Overlook; also frequently along the roads from Pleasant Valley to 
Moores Mill. At the north they appear oftener, chiefly because of 
the more frequent and larger outcrops of the slates and the thinner 
covering of surface material. 

There are reasons for thinking that the slates form a synclinal 
fold west of Matteawan and possibly the red slates at Matteawan 
and south of Paye’s pits respectively represent the east and west 


limbs, while those at Chelsea may represent the western limb of 
the succeeding anticline. 


$6 NEW YORK STATE MUSEUM 


Associations of the red slates. Along both the north and 
south roads from Pleasant Valley to Moores Mill the red slates 
occur just to the west of small conglomeratic limestone patches that 
have plainly been brought up by faulting. There is no way of de- 
termining the amount of displacement, but it is reasonably clear 
that the red slates le above the limestone and are younger and 
probably are not far from the base of the slate formation. 

Along the New York Central tracks near Fishkill Landing sta- 
tion are heavy-bedded members of the slate formation, such as 
make up most of it northwest of the Wappinger creek limestone 
belt. Assuming that the slates west of the Glenham gneiss belt 
have synclinal structure, these heavy members can not be far from 
the axis of the fold and lie several hundred feet above the red 
slates in stratigraphic position. The reason for the gneiss being in 
contact with, or in proximity to, the red slates along the Glenham 
belt, while the limestone conglomerate has that position at the north, 
is clearly due to greater vertical movement of the older rocks at 
the south and west. 

The red slates have not been noted within this quadrangle north- 
west of the Wappinger creek belt. According to the writer's ob- 
servations, the companion members of the red slates southwest of 
that belt, although sometimes showing heavy beds and even fine con- 
glomerates like those seen at the northwest, are prevailingly more 
fissile and splintery mud rocks of blackish-gray color. ‘These also 
occur along the northwestern margin of the Wappinger belt, but 
farther northwest give way to beds of coarser sediments. 

Quartzite near Rochdale. Along the road from Manchester 
Bridge to Pleasant Valley, east of Wappinger creek, between the 
farm of A. W. Sleight and that of George E. Smith at Rochdale, 
are prominent ledges of compact quartzite which rather strongly 
resembles some varieties of the basal quartzite. These ledges are 
portions of a continuous strip which can be traced from a ledge on 
the farm of A. W. Sleight just north of the Overlook road north- 
ward, roughly parallel with the Pleasant Valley road, to George 
E. Smith’s house. Just south of here it crosses the road and ends 
at the bank of the creek west of the house. East of the road it 
ends just beyond the barn south of the brook shown on the map, 
which apparently occupies a fault between the quartzite and the 
slates to the north of it. This quartzite is bounded entirely by the 
slates, except where it disappears in the creek. Here it is only a 
short distance from the Trenton limestone at Rochdale. Along the 


GEOLOGY OF THE POUGHKEEPSIE QUADRANGLE 87 


eastern contact with the slates, about one-half mile south of Smith’s 
house, the quartzite shows a strike of n. 20° e. and a dip of about 
6o° e. A mile and a half to the southeast, on the farm of Eugene 
Storm at Overlook, is a large block of compact whitish quartzite 
identical in character with that just described. This is cut off by 
a fault at the south against the slates. It can be traced only a short 
distance northward and disappears beneath the drift. This mass 
apparently belongs with the strip first described. 

This quartzite is probably an interbedded member of the slate 
formation. Its exact equivalent has not been noted elsewhere 
within the quadrangle. 


MISCELLANEOUS FAULTED LIMESTONES WITHIN THE HUDSON RIVER 
FORMATION 

Arthursburg. Three small patches of limestone are faulted in 
with the slates at Arthursburg. One of these is near the Central 
New England Railroad station. The impure shaly limestone is 
exposed in the railroad cut and forms a conspicuous knoll, which is 
situated partly on the railroad property and partly on the estate of 
Obed Hewitt. It is bounded on all sides by the slates and is hardly 
more than one-fourth of an acre in extent. It occurs along the north 
ward projection of the line of faulting that farther south forms the 
western boundary of the angular portion of the Fishkill limestone 
north of Hopewell Junction. Its present positicn is due to this fault 
and marks its northward continuation. <A careful search showed 
that the limestone does not occur in the neighborhood to the west of 
this fault. 

A iew hundred yards to the northeast of the station, on the read 
ascending the hill toward Beekman, conglomeratic limestone, with 
pebbles squeezed and elongated, outcrops along the road just north 
of the old schoolhouse. 

One-fourth of a mile north of this outcrop on the farm of G., L. 
Wiley, just southeast of the private cemetery, the limestone is 
exposed on a knoll just north of the brook. Some bluish-gray beds, 
like those seen at Rochdale, are present. The conglomeratic facies 
is absent. The beds strike n. 10° w. and dip 55° e. The knoll is 
entirely surrounded by the slates. The topography suggests a fault 
more or less parallel with the brook at this place. The fault just 
referred to as projected north from the Fishkill limestone dies 
away to the northward. 


88 NEW YORK STATE MUSEUM 


An unmistakable fault passes southeastward from Arthursburg 
and intersects the strike fault that follows the line of the old Clove 
branch railroad bed. 

The shaly beds near the station are probably younger than the 
conglomerate, while the latter is probably younger than the mass 
near the cemetery from which the conglomerate may have been 
eroded. These small masses are all separated from each other by 
the slates and no others could be found. They are clearly small 
faulted inliers of the older rocks lying near or at the intersection 
of two faults, one of which exactly parallels a similar break bound- 
ing the Fishkill limestone just south, while the other is the north- 
ward continuation of a fault between that limestone and the slate. 

The fault features which mark the Highlands and the Fishkill 
limestone thus continue northward within the slate formation. 

Moores Mill. On the farm of Mr Skidmore, about one mile 
west of Moores Mill station, is a larger mass of limestone resting 
against the slates. It extends up the hill on the northwest side of 
the road and for a short distance through the woods, but on the 
west, north and east gives way to slates. On the southeast it 
passes beneath the flood plain of Sprout creek. The entire patch 
does not exceed an acre or so in extent. In the orchard west of 
Skidmore’s house the slate and limestone are mixed together. The 
limestone is of a gray color and somewhat crystalline and seamy, 
but has no distinctive character. No satisfactory readings could 
be obtained. 

East of the creek, one-half mile from Skidmore’s house, on the 
farm of Mr Houghtalin, is a small, precipitous ledge of limestone 
in place, apparently dipping to the east at a high angle. This ledge 
is in the angle formed by the two roads northeast of Houghtalin’s 
house. The topography just south of the ledge is that of a scarp, 
which continues for one-third of a mile southwest. The scarp slope 
for this distance is uniformly abrupt, but outcrops are concealed 
south of Houghtalin’s. The topography suggests a transverse break 
at the south along the line shown on the map. South of this break, 
along the base of the slope, outcrops are concealed by surface 
material for some distance, but farther on the slates outcrop in 
low-lying ledges and in some places lie close to the base of the 
slope. 

The discovery of these two limestone patches aroused the sus- 
picion that the valley of Sprout creek might be in the limestone, 
but careful search failed to show the limestone in any other out- 


7) =a 


GEOLOGY OF THE POUGHKEEPSIE QUADRANGLE 89 


crops with one doubtful exception. Along the bank of the creek, 
one mile northeast of Skidmore’s farm, a mass of limestone about 
fifteen feet square was found between the road and the brook. At 
the base it is made up of coarse limestone conglomerate, which is 
followed by arenaceous limestone. ‘This is succeeded by a finer- 
grained conglomerate. The apparent strike is n. 25° w. and the 
dip 34° ne. This was regarded as a boulder. It strongly 
resembles similar beds found in place to the northwest. It hardly 
seems probable that this small ledge would have been preserved in 
its present position. 

It is reasonably apparent that these two limestone patches have 
been brought to their present position by overthrust faulting, involv- 
ing a horizontal displacement of at least one-half a mile. At 
Skidmore’s the limestone has been eroded so as to expose the slates 
on which it has been thrust. The small ledge at Houghtalin’s is 


‘only part of a scarp which is for the most part concealed. 


The valley southwest of these two limestone patches is plainly in 
the slate. There is strong suggestion that it is along a line of strike 
faulting that extends from the Highlands northward beyond the 
limits of the quadrangle. The view which shows this best is that 
obtained from the western slope of the ridge southwest of Moores 
Mill. The conspicuous scarp on the west of the high hill west of 
Lagrangeville, which is seen so distinctly from Freedom Plains, lies 
along this line of faulting, while the northeastward continuation 
of the latter is marked by a hollow plainly visible at the elevation 
of the viewpoint just mentioned. 

East of Pleasant Valley. Three limestone masses are faulted 
in with the slates east of Pleasant Valley. The largest of these is 
farthest east of the three and is shown on the map along the north 
road from Moores Mill to Pleasant Valley. A small ledge of the 
limestone outcrops among the slates one-fourth of a mile south of 
the fork in the roads near Ivy’s house. This is separated from the 
main portion of the mass along the road by slates. East of Ivy’s 
house, occupying practically all of the small triangle formed by the 
roads as shown on the map, and north of here for several hundred 
yards, are ledges of conglomeratic limestone interbedded with 
Silicious limestones (silicicalearenytes') and limy shales. The dip 
is eastward. Low ledges of limestone outcrop on both sides of the 
road east of Ivy’s. On the east side of the road the conglomeratic 


1A name proposed by Professor A. W. Grabau for silicious limestones 
with sandy texture. 


go NEW YORK STATE MUSEUM 


member forms a scarp for some distance. The pebbles of the con- 
glomerate are squeezed out into a stringerlike appearance along the 
strike. 

At the east this limestone patch gives way to the slates. At the 
south limestone and slate are somewhat mixed. At the west the 
patch evidently rests by overthrust on the slate formation. At the 
north relations are very obscure. It probably dies away along a 
strike fault. 

Distinct fossil traces were not noted here. The silicious lime- 
stone often shows many rusty grains. The red slates outcrop less 
than one-fourth of a mile to the west. 

Farther west, along this north road, about one and a half miles 
east of Pleasant Valley, as shown on the map, squeezed limestone 
conglomerate and interbedded silicious limestones form a knoll 
north of the brook and outcrop along the crossroad leading north. 
The limestone dies away at the north and is entirely surrounded by 
the slates. This block is along the line of thrust that brought up the 
third patch to the south of here along the south road to Moores 
Mill. . 

About two miles southeast of Pleasant Valley is another patch 
of limestone conglomerate with associated silicious limestone. The 
latter here is often weathered and shows a distinct clastic rock with 
fine quartz grains predominating. The weathered surface is pitted 
and the rock friable from loss of the lime constituent. This rock 
could be equally well designated as a calcareous quartzite. It is 
very similar to the rock overlying, or interbedded with, the con- 
glomerate near Ivy’s house farther east, but perhaps is a little more 
silicious. It carries the same rusty grains. The writer was inter- 
ested to compare this rock with specimens collected from the Sprout 
brook limestone near Peekskill and was surprised to note the strong 
resemblance in texture, mineralogy and markings. 

This patch lies back from the road, about 500 or 600 yards east 
of J. Fleet’s house. It forms a distinct scarp which continues south 
in the slates along the road after the latter makes its southward 
turn just east of Fleet’s house. A thick band of the red slates 
comes in between this scarp and Fleet’s house and is crossed 
diagonally by the road. The conglomerate rests by overthrust on 
the slates at the west. This feature is shown at * Fox Hole,4 a 
local name for the precipitous scarp shown in plate 16 and 
figure 26. 


AayJeA Jursvatg JO Jsvoy Nos ‘WaAey Soop —[ JO JS¥o So}VIS oY} UO 9}LIOWO]SUOD oY} JO JsNIyIIOAC 


GEOLOGY OF THE POUGHKEEPSIE QUADRANGLE ope 


Pig. 26 Overthrust east of John Fleet’s. A, limestone conglomerate; B, silicious limestone; 
C, slate; F, fault 


_ When seen from above the conglomerate is coarse, but when 
examined along the edges of the eastwardly dipping beds the 
pebbles are seen to be squeezed out into stringers, so that the 
apparent coarseness can not represent the original condition. The 
dip is about 20° e. and the strike about n. 10° e. The calcareous 
quartzite was not seen in actual contact with the conglomerate, but 
is undoubtedly conformable. At the east the former is followed 
by the slates) Solenopora compacta, showing the char- 
acteristic very fine lines, was noted in the conglomerate. The 
‘quartzitic rock outcrops at intervals to the south for one-fourth to 
one-third of a mile, but gradually dies away. At the north the 
series ends more abruptly. 

The conglomerate at the last mentioned locality of those which 
have just been described is undoubtedly the equivalent of that 
which at Pleasant Valley and Rochdale overlies the eroded Beek- 
‘mantown, and there can be little doubt but that the conglomerate at 
the other localities is also the same. There is shown again the 
general tendency for the older rocks to be faulted up among the 
younger ones. 

Summary of features shown by the conglomerate and associ- 
Sated rocks. At Pleasant Valley and at Rochdale the con- 
glomerate and overlying or interbedded blue limestone resting on 
the eroded Beekmantown are prominently developed. At Rochdale 
the series is from 70 to 100 feet in thickness and at Pleasant Valley 
it is apparently about the same. At Sleight’s quarry near Man- 
chester Bridge the conglomerate and blue limestone is from 20 to 
30 feet in thickness, but certain faulting here makes it unsafe to 
tegard this change as marking a thinning of the limestone. F[ar- 
ther south along the Wappinger creek belt one can get no idea of 


Q2 NEW YORK STATE MUSEUM 


the extent to which this basal series is represented. Along the 
western margin of the Fishkill limestone, as shown east of the 
Glenham belt, the conglomerate has plainly been eroded so exten- 
sively that no idea of its original thickness can be gained. At 
Swartoutville the conglomerate is apparently thin and passes 
quickly into a series of interbedded bluish limestones and gray limy 
shales. The impure shaly limestones along the railroad track west 
of Hopewell Junction, at the apex of the limestone angle and those 
near Arthursburg station, are probably near the base of the slate 
formation. At Arthursburg the conglomerate is present at a dis- 
tance of a few hundred yards from the shaly limestones at the 
station. In the localities east of Pleasant Valley, which have been 
described, the conglomerate is interbedded with and followed by 
calcareous quartzite, the blue fossiliferous mud rock not being 
present. 

At the east within this quadrangle the rocks associated with the 
conglomerate, though varying in texture from shaly rocks to 
quartzitic ones, tend to be more silicious than those farther west. 
Folding and faulting have doubtless brought the two into their 
present rather close proximity. 

Other varieties within the slates. This formation shows many 
varieties of more or less altered clastic rocks, ranging from muds to 
fairly coarse conglomerates. While folding and faulting have pro- 
duced the greatest confusion, it seems possible to make out the 
general sequence. The writer’s observations favor the idea that the 
calcareous conglomerate and overlying quartzitic limestone represent 
an eastwardly overlapping sea. These were quickly followed in 
some cases by limy mud rocks and in others by argillaceous cnes. 
These were both succeeded by a clastic series of both argillaceous 
and calcareous nature with one and sometimes the other element 
in excess and occasionally with so much lime as to form an impure 
lime rock. The varieties varied in texture and followed each other 
irregularly. Impure argillaceous muds predominate, and are inter- 
bedded with limy muds and grits of varying thickness, but often 
attaining several feet. Grits often reaching conglomeratic texture 
are frequent. In these, the larger particles range from the size of a 
pin head through that of a pea to that of a walnut and larger. 

On the whole, the finer-textured members are more characteristic 
of the basal portions of the series and the coarser and gritty layers 
of a higher horizon. Such a series as has just been described is 
folded in between the red slates of Matteawan and those south of 
the clay pits at Paye’s brickyard, and the members are exposed at 


West side of Hudson river showing location of Marlboro and . 


“Tllinois ”’ mountains 


GEOLOGY OF THE POUGHKEEPSIE QUADRANGLE 93 


many points between or along the strike to the north and south, and 
along the New York Central Railroad track. The coarser, gritty 
members, or conglomerates, were noted about midway between the 
strikes of the two bands of red slates. 

The red slates suggest that they were formed under conditions of 
regular exposure to the atmospheric influences, perhaps on extensive 
tidal flats or river deltas. It is probable that these rocks were formed 
on a gently subsiding sea floor which occasionally allowed for partial 
nonmarine conditions of sedimentation. The relative horizon of the 
red slates is indeterminate, but is probably not far from the base 
of this formation. This is indicated by the geographical associa- 
tions with the conglomerate and their absence northwest of the 
Wappinger creek limestone. 

North of Camelot, along the railroad track, almost to Pough- 
keepsie, crushing has affected all members much the same, producing 
coarsely splintered slates. The great confusion exhibited by the 
slates about Poughkeepsie and on the west of the river north and 
south of Highland seems to have been due very largely to the effect 
of heavy beds interbedded with thinner ones. 

Along the western bank of the Hudson from Marlboro to a 
point two miles or so north of Highland, the rocks are quite similar 
to those along the east bank. Westward from the Hudson the rocks 
grow prevailingly coarser. The section along the Central New 
England track between Highland and Lloyd shows thick masses of 
quartzitic rocks interstratified with coarse grits and conglomerates. 
The latter form relatively thin beds, perhaps from six to eight feet 
in thickness, often with pebbles from two to four inches in their 
longest diameters, embedded in a matrix of finer conglomerate; 
while in the grits are scattered pebbles ranging from the size of a 
walnut to that of a man’s head. These coarser types prevail along 
the track west of Highland station and are particularly well shown 
just east and west of the overhead trolley bridge on the New Paltz 
road and at the foot of the mountain along the road just south. 
These rocks appear to be the northward continuation of the rocks 
of “Illinois mountain.” That some of the strata were deposited 
under marine conditions is indicated by the fossils that have been 
discovered on the eastern slope of “ Illinois mountain” and on 
Marlboro mountain farther south. While this is true, there 
appears to have been a gradual coarsening of sediments westward 
which suggests changed conditions in the source of supply, lying to 
the eastward, as though terrigenous sediments gradually encroached 
westward and contended with marine deposits. This idea would 


94 NEW YORK STATE MUSEUM: 


seem to fall in line with what we know of the record of closing 
Ordovicic time in eastern North America. 

Some of the members of the slate formation on the west oi the 
Wappinger limestone belt may be much younger than those on the 
east of it. They may be thought of as having been preserved partly 
on account of their occupying, in general, a downthrow position 
with reference to a tendency to thrust and reversed faulting to the 
eastward, as well as on account of being west of the axis of maxi- 
mum folding. 

About two miles north of Poughkeepsie are strata of black, some- 
what carbonaceous slates in which graptolites have been found. 
They indicate changed conditions of sedimentation from those 
which chiefly prevailed during the accumulation of these rocks. 
These black slates have been thought to be of Utica age. 

Structural features. Where the stratification dip has been 
determined on what is plainly the limb of a fold, it is chiefly east- 
ward. Judging from the conditions shown in the Fishkill limestone, 
the structure is that of minor folds within a system of larger ones 
with a tendency to overturning. The presence of strong cleayage 
usually obscures everything in surface outcrops. 

The dimensions of the larger folds seem to be smaller at the 
north and northeast than at the southwest, and the folds seem to be 
more open at the north. The slate ridge just east of Freedom Plains, 
which ends abruptly at the south at a point due east from that 
hamlet, has synelinal structure of a rather open character. At 
various points along the southern portion of its eastern slope it 
shows the slates dipping to the west into the hill. To the north, 
along the south road from Moores Mill to Pleasant Valley. the 
red slates come up on the western limb of this syncline and about 
three-fourths of a mile farther northwest they appear again appar- 
ently on the western limb of the succeeding anticline. 

There was a tendency to form irregular folds. This is shown on 
a small scale in plate 18, in which we have a small overturned and 
compressed syncline on the right of the picture, followed by an 
irregular anticline, which becomes compressed and pushed up at 
the west, and then another compressed syncline not distinct in the 
photograph but similar to the first. In this instance, it is seen that 
the production of anticline and syncline in the middle part of the 
ledge has been incomplete. With similar tendencies prevailing in 
the larger folds, it is easy to see how, along the western portion of 
the irregular anticline, there would have been a tendency to over- 
thrust. Crumpling is not uncommon. The wrinkles vary from 


AdJVA JULsvs[q JO jsva Sopitu I91Y} “WIL; SAA] WO SozVIS 9Y} UT spyosy 


—.- 


GEOLOGY OF THE POUGHKEEPSIE QUADRANGLE 95 


 minttte size to the dimensions shown in plate 19. These features are 


more common at the east. 

Cleavage is so prominent in surface outcrops that the stratifica- 
tion dip is usually obscured. The prevailing eastward dip indicates 
a common eastward inclination for the cleavage. The presumption 
is that stratification and cleavage often coincide or approximate each 
other very closely. Where the cleavage is not dominant to the 
exclusion of the stratification, this fact is often observed. 

Jointing is well displayed in Matteawan along the Newburgh, 
Dutchess and Connecticut track. A prominent set of joints shown 


Mivere has a general strike of n. 20° e. and a dip of 80° w. 


Seme of the faults within the slates have been alluded to in 
describing the limestone patches within this formation. 

Extending in a northwest direction approximately parallel with 
the read from Brush to Arthursburg, as shown on the map, is a 
clear transverse fault. This break is best seen from the southeast 
near the old railroad bed. This break intersects a line of strike 


‘faulting at Arthursburg, and probably ends at that point. The 


strike fault just mentioned dies away to the northward. Continued 
south, it bounds the limestone triangle north of Hopewell Junction 
on the west. 

The high hill northwest of Lagrangeville is bounded by a fault 
scarp on the west. This scarp is a conspicuous cliff east of the 
road from Lagrangeville to Freedom Plains. The high hill north- 
west of Billings is bounded on the south by an east-west fault 
whose scarp is very conspicuous. 

The other lines of fracture shown on the map have already been 
referred to. | 

A long line of swampy lowland, beginning two miles north of | 
Freedom Plains and running northward toward Pleasant Valley, 
appears to mark a line of crustal weakness similar to that which 


extends from Hopewell Junction to Manchester Bridge. 


The fault which bounds the western strip of the Wappinger creek 
limestone on the north may extend across the Hudson and bound 
“Tilinois mountain ”’ on the north. 

Metamorphism and alteration. The members of the slate 
formation show an appreciable increase in metamorphism toward 
the east within the quadrangle, passing into slaty phyllites and gray- 
wackes. These rocks do not develop into perfect schists like those 
oceurring a few miles to the eastward, but pellets of decomposed 
ferruginous particles, suggesting former garnets, were noted in the 
phyllites east of Arthursburg. Veins, veinlets and nests of quartz 


96 NEW YORK STATE MUSEUM 


are most abundant in the northeastern part of the area. Sandstones 
have been changed into quartzites. 

Summary. There is no evidence at hand that any slates of 
the quadrangle are older than the limestone conglomerate that has 
been discussed, either as overlying the Beekmantown or as isolated 
inliers within the slates. The slate formation was ushered in by 
this basal conglomeratic layer. The area of deposition of the latter 
may have been much more extensive than is indicated by its present 
faulted outcrops. The period of its formation was of short dura- 
tion. 

The most that can be said of the slate series is that it began in 
some horizon of the Trenton and perhaps ranges upward an 
indefinite distance into the Cincinnatian. Probably a large portion 
is of Trenton age. . 

The Utica may be present, although the graptolite beds that have 
been so called more probably represent an early invasion of the 
Utica fauna in Trenton time in what is known as the Normanskill 
subepoch. Some of the slates may be contemporaneous with the 
Utica as developed elsewhere to the north, and possibly even 
younger ; or they may all be of Trenton age. 


PREGLACIAL HISTORY OF THE RON 


Old valleys of the Tertiary cycle. During the erosion cycle 
inaugurated by the Postcretacic uplift, the Hudson river then, as 
now, must have been the dominant factor in the drainage of this 
and adjacent areas. A broad valley region was formed and the 
tributaries of the master river steadily pushed their valleys 
eastward. The early Tertiary valley of the Hudson itself is now 
represented by old rock terraces preserved at different points back 
from the river’s edge. Near Poughkeepsie they have an elevation 
of about 200 feet. 

The rock valleys of the present tributary streams are in most 
cases out of proportion to the present size of those streams. Dur- 
ing the time the Hudson river occupied the valley now marked by — 
the terraces that have just been alluded to, its tributaries widened 
their own valleys a good deal and acquired their present open char- 
acter. These branches formed a drainage system of the second 
order within the broad valley region of the main river and a some- 
what advanced stage of mature topography was attained. During 
this time the various lines of crustal weakness became marked off 
into their present prominence, without necessarily becoming prom- 
inent lines of drainage; simply responding in a logical way, on 


Plate 19 


Crumpled slates east cf Freedom Plains 


yo 
GEOLOGY OF THE POUGHKEEPSIE QUADRANGLE Q7 


account of reduced resistance, to the base-leveling forces of the 


stream a tremendous advantage. It was able to sink its channel 
at a very rapid rate. The larger tributaries were able to deepen 
their gorges near their mouths and for some distance back from 


the location of the aqueduct of the great metropolitan reservoir in 
the Catskill mountains. These have yielded important data regard- 
ing the preglacial channels of these streams. Professor Kemp has 
summarized and discussed these data in an interesting paper.? 

_ Borings across the Hudson have been made at Pegg’s Point, at a 
point one-half of a mile north of that place, at New Hamburg and 
at Danskammer within this quadrangle, and at Storm King just 
south of Newburgh. 

' The most northerly line of borings is known as the “ Tuff 
crossing.’ From this, only wash borings were secured. The river 
here is only 2200 feet wide. 

At Pegg’s Point the river narrows still more. A diamond drill 
Was sunk 720 feet from the west shore and reached the slate at 
223 feet below sea level. Another sunk 440 feet from the east bank 
reached the limestone at 92 feet. The distance separating these two 
Dorings is 1040 feet. Professor Kemp believes that a deep and 
telatively narrow gorge lies between. Several lines of wash borings 
at this place gave depths to supposed bed rock varying from 139.5 
feet to 256 feet in what would perhaps be thought of as the deepest 
part of the river. . 

_ At New Hamburg the river is 2300 feet wide. Drill borings on 
each bank found the slate beneath the limestone. At the point of 
boring on the east bank it was reached at 220 feet; on the west at 
51 feet. Only wash borings were made in the river bottom. These 
ftanged from 130 feet to 263.5 feet below tide. 


1Buried Channels beneath the Hudson and its Tributaries. Amer. Jour. 
Sci. Ser. 4. 26:301-23. 


i eal 


98 NEW YORK STATE MUSEUM 


At Danskammer the stream is about 3500 feet wide. The results 
of wash borings gave a range in depths from 133.2 feet to 268.5 
feet to supposed rock bottom, but the evident irregularity and 
variability would seem to indicate a bed of loose material at these 
depths at this crossing. 

At the Storm King crossing the drill brought up from a depth of 
617.4 feet a core of granite just like that on the east bank of the 
river, which it had penetrated to a distance of 8.8 feet. The drill 
was thought to have reached rock bottom at this point at a depth 
of 608.6 feet not far from 750 feet from the east bank. 

Casper creek was tested near its mouth by wash borings. The 
lowest point thus reached was 67 feet below tide. 


Fig. 28 The Casper creek crossing. (After Kemp) 
In Wappinger creek one wash boring below the fails reached ° 


depth of 50 feet below tide. Of three core borings, the maximut 
was 39 feet. 


Fig. 29 The Wappinger creek crossing. (After Kemp) 


A proposed line of the aqueduct crossed Fishkill creek near th 
village of Fishkill. Everything is beneath the drift at this point 
Of two core holes, the deeper reached the limestone at 40 feet beloy 
tide. After penetrating 8 feet of limestone, the drill encountere 
fine yellow sand in which it continued for 60 feet, when the hol 
was abandoned. This crossing is about five miles back from th 
Hudson. 


Ss im Sy inl hs eG CREEK 


Fig. 30 The Fishkill creek crossing. (After Kemp) 


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ae 


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ps 


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cl 


PEGGS POINT 


aS 1040" 


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7 
1 
1 
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ho 
ine 
ae 


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hs 
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EE \N 
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BDANSKAMMER 


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Tv, 
~ v 
> TON 
Viv'v vy BREAKNECK 


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Cha 
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PY STORM KING 
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¥ Ss M 
4 fe vy 


eee owcnes ALINE OF WASHBORINGS “\y v 


Opie 


ett NEN: 

Ree 

Fig. 27 Sections showing borings across the Hudson river at Tuff crossing, Peggs Point, New Hamburg, Danskammer 
and Storm King (after Kemp) 


Say 3 = 
ae 
. 


vw ME & 


GEOLOGY OF THE POUGHKEEPSIE QUADRANGLE 99 


The above-given numerals and description were taken from Pro- 
fessor Kemp’s paper. The general conclusions to be drawn from 
these facts to which Professor Kemp has called attention, are that 
the Hudson river occupied a deep gorge at the close of the Tertiary 
period and that its tributaries emptied into it from hanging valleys. 
Unless a deep gorge exists at the Pegg’s Point crossing, as discussed 
above, a rather large gradient between this point and Storm King 
would have to be assumed. 

The borings south of Fishkill Village suggest that this creek 
deepened its gorge some distance back from the Hudson during late 
Tertiary time. The other tributaries probably did the same to an 
extent commensurate with their size and erosive power. All the 
tributaries, however, occupied hanging valleys with reference to the 
bed of the main stream. 

The boring records also show that much glacial stuff now lies in 
these buried channels. 


GILJNC IDE, GIEOIIOE Ne 


Erosion. ‘The elevation of the land at the close of the Tertiary 
is believed by many to have ushered in the glacial epoch. The 
passage of the ice sheet over this region is marked by grooves and 
striae and characteristic deposits of surface material. The ice sheet 
may have assisted in gouging out the channel of the Hudson. 

The following is a summary of observations by the writer on the 
direction of glacial striae and grooves in different parts of the 
quadrangle. West of the Hudson about two miles northwest of 
Highland, along the road to Lloyd, a deep glacial groove was noted 
with bearing true s. 15° w. One and a half miles west of Milton 
another fine groove gave a reading of true s. 9° w. Fine roches 
moutonnees occur to the west of “Illinois mountain” south of 
Lloyd. 

East of the Hudson in the eastern part of the city of Pough- 
keepsie, near the driving park, striae were noted with bearing true s. 
about 14° w. and farther east, just west of the central strip of the 
Wappinger belt along the Hackensack road, a reading of true 
S. I’ w. was taken. Near the Central New England Railroad at 
Poughkeepsie the striae had a bearing of true s. about 26° w.; north 
of Poughkeepsie near quadrangle boundary, east of Fallkill creek, 
true s. I1° w.; one mile north of New Hackensack, n. 21° w.; near 
the Hudson, north of Fishkill Landing, true s. 33° w. 

Some of the strike fault scarps, as, for instance, those of Bald 
hill, Mount Honness and Shenandoah mountain of the Highland 


4 


100 NEW YORK STATE MUSEUM 


spurs, and the fault east of Freedom Plains, appear to show the 
effects of glacial plucking. 

The Highland crests were buried by the glacier. Some places 
along the northern slopes show polishing effects (see plate 6). 
The excavation of the valleys between the northern spurs of the 
Highlands was probably materially assisted by the ice. 

Deposits during the advance. Drumlins, or drumlinoid 
masses of till, are rather numerous in the quadrangle and often are 
conspicuous features of the topography. They seem to be deposits 
of the advancing ice sheet which molded them by pressure into their 
usual elongated domelike shapes. These masses greatly obscure 
the structural relationships over much of the area. They are the 
most conspicuous features of the ground moraine. The larger part 
of the veneer of till, which is very plentiful, probably dates from 
the advance of the glacier. About 200 feet of boulders and sand, 
which rest on the bottom of the Hudson gorge, probably are a part 
of the ground moraine. 


RETREAT OF THE ICE Srimizay 


It is generally held that accompanying and following the retreat 
of the Wisconsin ice sheet from this region there was a slow sub- 
sidence of the land. At this time a large body of water filled the 
old valley of the Hudson within this area. It would appear that 
the subsidence went on gradually and that during the earlier stages 
much sand, gravel and sandy clay was deposited on the earlier 
boulder material that covered the bed of the gorge to a depth of 
200 feet, and then a thin layer of boulders representing a probable 
flood of floating ice, and then typical river deposits. Finally, it 
would appear that the subsidence may have brought in estuarine 
conditions, at which time the Hudson river clays were laid down. 
These considerations assume an open gorge and postulate the prob- 
able deposition of the clays entirely across it, their present condition 
having been brought about by later dissection. It is proper to state 
that there are exceptions to this idea. Professor Woodworth, from 
a study of the entire Hudson and Champlain valleys, holds the 
opinion or belief that, during the deposition of these clays, the 
Hudson gorge was filled with a long tongue of ice against which 
were standing bodies of water at a higher level than water could 
have assumed in the open gorge. He cites many observations to 


LeSee nie ok: Kemp. Buried Channels. beneath the Hudson and its Tribu- 
taries. "Amer. Jour. Sci. Ser. 4. 10908. 26:322. 


GEOLOGY OF THE POUGHKEEPSIE QUADRANGLE IOI 


‘show that the clays, and overlying sands and gravels are best 
explained as depositions under such conditions.1 Woodworth’s 
hypothesis does not call for so great a subsidence of the land as the 
other, and logically explains the present bisected character of the 
‘clays as their original condition. The proximity of the ice during 
the deposition of the so-called Champlain deposits is shown in 
several ways. It seems quite reasonable, however, to explain the 
upward more or less perfect passage from coarse to finer detritus in 
the Hudson gorge as due to gradual deepening, and a passage from 
_fluviatile to estuarine conditions which would furnish the conditions 
tor the accumulation of the finer material. 
Terraces. The finer material in question takes the form of 
stratified deposits of clay, capped with sand and gravel, which occur 
in the form of terraces at various places along the Hudson gorge. 
A number of these are in this quadrangle. 

Such a terrace begins somewhat over a mile north of Fishkill 
Landing and extends for a mile north of that point, varying in 
width from about one-fifth to three-fourths of a mile. It is about 
100 feet high at the outer edge and a few feet higher at the inner 

edge. It is followed on the north by a lower terrace varying from 
30 to 40 feet in height, with varying depths of clay and covered 
with coarse gravel. On the west bank of the Hudson at Roseton 
-and at Danskammer gravel-covered terraces also occur. These are 
somewhat higher than the north terrace on the east bank. Terrace 
deposits also occur at Marlboro. 
At New Hamburg the deposits are a good deal coarser and 
have a terrace delta form. The coarse sands and gravels of this 
terrace and their general relations, as well as the Roseton and 
_Danskammer terraces, are thought by Woodworth to “compel the 
belief ” that they were deposited against the ice. In the case of the 
| Roseton terrace, he states that there are signs of inthrusting of drift 
. from ice movement (loc. cit. p. 119) and further that the terrace 
not be attributed to a river pouring into an estuary after the 
' disappearance of the ice. 
. _ The diminishing altitude of the terraces northward has been inter- 
_ as favoring the idea of their formation against the ice in 

glacial lakes. The coarser material overlying the clays has been 
attributed to the retreat of the ice front beyond the mouths of tribu- 
i tary stream valleys, allowing an influx of coarser sediments. 


‘6 


1 Ancient Water Levels of the Champlain and Hudson Valleys. N. Y. 
State Mus. Bul. 84, 1905, p. 66-265. 


) 
; 
1 


102 NEW YORK STATE MUSEUM 


By others, the lower level at the north has been attributed to 
erosion accompanying elevation, and the coarser sediments to the 
same cause. 

C. I&. Peet* has made the observation that, if the valley between 
the low terrace just south and north of Carthage Landing and the 
slightly higher one on the west of the river at Roseton and Dans- 
kammer were filled with ice, the latter was stagnant, and may have 
stood on the lower terrace at the east. He also admits the possibility 
that the terraces may have been continuous and that the lower one 
on the east is the product of the erosion of higher deposits. 

Later, in discussing the history of the “ Hudson water body and 
the successive positions of the ice as it retreated through the Hud- 
son valley, Peet? states that the ice front appears to have assumed 
two distinct phases in different parts of the valley. In some parts, 
notably the narrower ones, it is believed that the ice protruded down 
the valley and that accumulations took place at the edge of this 
ice-tongue, or between it and the valley wall. The -deposits at 
Carthage Landing and New Hamburg might represent such con- 
ditions, but the valley ice was probably not an active contributor, 
although at the latter place waters from the valley ice may have 
been active in the early stages of the plateau building. In the 
broader parts of the valley the deposits were probably deposited in 
an embayment of the ice front. 

Peet cites many facts to show that the Hudson water body may 
have been a lake made by a barrier at the south, or a succession of 
lakes made by a succession of barriers or by a migrating barrier, 
and, on the whole, leans toward the lake hypothesis as against a 
salt water body. The reader is referred to the original paper 
(see loc. cit. p. 640-56). 

It is probable that a series of glacial lacustrine basins at the south 
would have allowed both for open water and the many characteristic 
glacial phenomena in connection with the deposition of this 
material. 

On the submergence hypothesis an elevation of between 100 and 
150 feet was necessary for the bisection of the delta at New Ham- 
burg, and at this time the deposits in the gorge of the Hudson may 
have been dissected, although to a greater extent in the case of the 
main river. The moot point seems to be the extent to which the 
gorge was submerged by the sea. 


_ 1 Journal a8 Geology. 12:445. 
2loc. cit., p. 618-21. 


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0} osdooyYSnog wor; pros oy} Jo ysva “wsey Ssurydmoy Ieou Yoo19 Josurdde Ad FO oovs104 JoAo]-Ysty oy} JO uor10d vy 


Q2% 318Id 


GEOLOGY OF THE POUGHKEEPSIE QUADRANGLE 103 


Well-preserved sand and gravel erosion terraces occur at fre- 
: quent intervals along Wappinger creek. These are best shown in 
the open portion of the valley of this stream in the neighborhood 
' of Manchester Bridge and between that hamlet and Rochdale. The 
road from Manchester Bridge to Rochdale for a mile north of the 
- former place closely follows the edge of a fine terrace that drops 
with uniform slope from the 160 foot level to the present flood 
_ plain of the creek. The cemetery at Manchester Bridge is built 
on a projecting tongue of this fine terrace which is broken by the 
_ limestone knoll on which Mr George Byer’s house stands. North 
of here it may be followed for a short distance. 

South of Rochdale, to the east of the Pleasant Valley road, on 
_ the west side of the creek, the present flood plain makes a large 
embayment to the west, north of Frank De Garmo’s house. This 
embayment is fringed by a fine terrace, a portion of which is shown 
in plate 20. Other terrace remnants may be followed southward 
along the creek. 

These dissected deposits clearly belong to an epoch when the 
creek valley was flooded and the creek was able to aggrade its 
valley floor to the level of these terraces, at least. It was probably 
during this time that the delta deposits were making at the mouth 
_ of the creek, whatever the conditions there may have been. These 
features would appear to have been intimately connected with the 
retreat of the ice sheet which, as it melted, would have furnished 
both the floods and the material. This material is in the form of 
sand and gravel. A good deal of finer detritus must have been 
- carried out into the Hudson gorge. 

To allow for this accumulation of sand and gravel in the old 
valley of the creek, either there must have been a body of standing 
water in the Hudson gorge nearly 200 feet higher than now, or the 
land must have been much lower than now. 

Fishkill creek and its tributaries were also able to aggrade their 
' valley floors. Gravel deposits belonging to a former higher level 
_ form imperfect terraces at different points. In some places, the 
gravels look like outwash plains during a short halting of the ice, 
as in the vicinity of Hopewell Junction. The Newburgh, Dutchess 
& Connecticut Railroad apparently cuts a series of terrace remnants 
from Hopewell to Brinckerhoff. Fishkill Village is located on a 
_ terrace at the 200 foot level which extends southwest to Glenham. 
Small, but perfect, terrace levels along brooks tributary to Fishkill 
creek, belonging to a stage in the subsidence of the water correspond- 


104 : NEW YORK STATE MUSEUM 


ing to the rock barrier over which the main stream flowed at Glen- 
ham, are preserved near Johnsville. 

Kame deposits. These are prominently developed in places 
along the northern margin of the Fishkill mountains. A con- 
spicuous group occurs along the Cold Spring road south of Fish- 
kill Village, near the quadrangle boundary. 

Kame moraine deposits are prominently developed south of 
Johnsville along the eastern base of Mount Honness, and still farther 
south along the western read from West Fishkill Hook into the 
mountains. 

The brook flowing north from the mountains, through the hollow 
of East Fishkill Hook, cuts through similar masses. 

Kames are noticeable features along the road from East Fish- 
kill Hook to Shenandoah. Northeast and east of that hamlet they 
are pronounced topographic forms guarding the approach to 
Shenandoah hollow (see plate 21). 

Kames also occur along Casper creek between the Hudson river 
and the Poughkeepsie road (see plate 22), and near Camelot. 


POSTGLACIAL EROSION 


After the retreat of the glacier either the land, which probably 
was at a higher level than now, remained stationary, while the 
water level in the gorge subsided, or it was elevated. The tribu- 
tary streams, now greatly reduced in volume, meandered over their 
old floor plains and began the vertical and lateral dissection re- 
corded in part by the terraces described or alluded to above. Wap- 
pinger creek, in seeking an outlet to the Hudson, was confined 
near its mouth between narrower rock walls and began the bisec- 
tion of its old delta of the flood period. It readily found its old 
preglacial channel, which it tumbles into at Wappinger Falls. 
The precipice at this place forms a local base-level to which the 
stream is slowly reducing its bed at various places along its course 
at the north. 
_ Fishkill creek is off its old preglacial channel for some distance 
in Glenham, and between that hamlet and Matteawan. When the 
stream was superposed on its former flood plain it was obliged to 
make a wide detour at Glenham round the huge drumlin on which 
the cemetery of Matteawan stands. It eventually found bed rock 
and finally the contact between the limestone and the gneiss of the 

lenham belt, and has made the gorge shown in plate 23. At 
the northeast end of the carpet mill the creek crosses a fault between 


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Zz 93eId 


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Ce a1PTtT 


GEOLOGY OF THE POUGHKEEPSIE QUADRANGLE 105 


the limestone and the slate and from this point on cascades over 
the slates until its own delta is reached. It is probably along or 
very near its preglacial channel from Wolcott avenue southward. 
The preglacial channel north of here is probably to the southeast 
of the present course of the stream. 

It may be that during this time of erosion the Hudson cut its 
present gorge and that the gravel-covered, laminated clays are 
erosion terraces instead of benches laid down against the ice. 


THE PRESENT DEPRESSION 


Following the bisection of the Wappinger creek delta, the valley 
of the Hudson suffered the depression that produced the present 
estuary and the later channel of Wappinger creek was submerged 
(see plate 24). Fishkill creek filled up its gorge to tide level and 
produced its present delta. 


OTHER DRAINAGE FEATURES AND ADJUSTMENTS 


Near Gregory’s mill at Old Hopewell, Fishkill creek was deflected 
by the drift and imposed on the limestone through which it has cut 
a gorge. 

The rock valley of Casper creek, at points north of the Hope- 
well branch of the Central New England Railroad, suggests a once 
more powerful stream which may have drained a larger area to the 
north of this quadrangle along the valley of the brook that rises in 
the swamp east of Van Wagner, and now flows north to join a south- 
ward flowing stream of considerable size, and which reaches Wap- 
pinger creek by making an abrupt turn to the east-northeast. 

The course of the Fallkill near Poughkeepsie suggests that this 
stream has utilized certain fault features. Fishkill creek, along its 
course within the quadrangle, makes a number of bends to the 
northeast that are in line with the fault features of the Fishkill 
limestone. 


LAND FORMS 


These are apparently of two fundamental types: those produced 
by a sort of block faulting and those produced by folding, accom- 
panied by faulting. Each is distinct, but is modified by the other. 
Both apparently date from the time of the Green mountain 
revolution. 

At the close of Cretacic time this region was a peneplain. A re- 
elevation introduced the history of the present topographic aspect 
of the quadrangle and subsequent erosion presents the striking dis- 


106 NEW YORK STATE MUSEUM 


cordance between the present topography and relations and those of 
Precambric and early Paleozoic time. 

The Precambric gneissic floor appears to have behaved in a 
measure as though it had no load. It was twisted and broken into 
blocks like a piece of glass and thrust up into the overlying forma- 
tions, the force of the shove diminishing to the northwest. The 
plateau type of the Highlands is primarily the result of upward 
thrust as a mass and secondarily the effect of the resistant quality 
of the Precambric rocks when subjected to erosion. The present 
topographic level of the Fishkill limestone would appear to indicate 
a normal position for the limestone now. Primarily, however, it is 
a faulted up thrust block ; erosion has exposed the older stratigraphic 
series which were thrust up into the overlying slates, 

' The northern valleys of the Highlands represent down-faulted 
masses of the younger rocks which later erosion cycles discovered 
and removed. 

As superstructures on these basal features are forms connected 
with folding and breaks along the strike and dip. 

Influence of the petrographic character of the rock. The low 
average level of the Hudson valley is attributable to the ease with 
which the slates are broken up and removed. The relatively low 
topographic level of the Fishkill limestone, corresponding with its 
lower stratigraphic position, is deceptive. In this case, the removal 
of the slates and the erosion of the limestone obscures the structural 
position brought about by faulting. 

The present altitude of the high ridge forming “ Illinois moun- 
tain” is due in part to the resistant character of its grits. 

~The resistant quality of the metamorphosed rocks in the eastern 
part of the quadrangle has been a factor in producing their present 
relief. 


ECONOMIC GEOLOGY 


The agricultural industry. The agricultural interests are 
chiefly those of fruit growing and dairy farming. The former is 
conducted on an intensive plan on the hilly land west of the Hudson 
where well-drained hills of tilted slates, covered with a veneer of 
till and coarse gravel, afford highly suitable soil conditions for 
growing fruit of excellent quality. Large consignments of peaches, 
apples, pears and small fruit are sent to New York city and New 
England markets and some growers find a highly profitable business 
for fancy fruit in the markets of England. Grapes are also a suc- 
cessful and important crop. 


YoU SuIyxoo] ‘sinquiezZ MON JO YMOs sop OM} das se UOSpNFT IY} Fo 28108 poumosq 


- a be anor Tr 


GEOLOGY OF THE POUGHKEEPSIE QUADRANGLE 107 


Fruit growing is also practised east of the Hudson. Nearly 
every large farm has its apple orchard, some of which are of large 
size. Peaches are also successfully grown and apparently are grow- 
ing in popularity as an investment. Some fine fruit is grown in 
small orchards along the northern slopes of the Fishkill mountains. 
The Hudson river affords favorable temperature conditions for the 
_ budding season and insures good crops. The ravages of the coddling 
moth and other injurious insects are, however, sometimes extensive. 

The importance of the climatic influence of the Hudson river as a 
successful factor in fruit growing is clearly recognized. Fruit is 
not so successfully grown out of reach of this influence, even on 
soils of the same character and with similar drainage. 

Dairying is perhaps the largest farming industry and the one 
most widely practised. The area enjoys unusual facilities for trans- 
portation of farm products. 

Soils. The glacial ice, as shown above, moved in a course 
generally roughly parallel with the longer axes of the rock ridges. 
This fact seems to have had an influence on the character of the 
soil along these ridges. It is noticeable that the upland soils have a 
definite relation to the underlying rock. 

Lower levels, which mark the flood epoch of the waning ice 
sheet, have sandy and gravelly soils, with clayey subsoils, and are 
often of terrace form or in kamelike masses. In addition to these 
are the drumlinoid masses of somewhat more compacted character, 
often attaining or approximating boulder till. Finally, there are 
the alluviums of the river bottoms. 

The limestone areas are considered the finest grass lands, but 
all the upland soils yield good grass crops. The gravelly river 
bottoms are usually good corn soils. The more sandy terrace soils 
are suitable for garden truck or early fruit. The slaty hill sides 
usually give good apple-growing soils when not too clayey. 

_ The finest farms are in the limestone areas, but the slaty uplands 
of moderate elevation are highly valued for both of the principal 
farming pursuits of the present day. 

Clays. All the important clays of this area are of sedimentary 
character and belong to Pleistocene time. 

A number of important brick industries are located within the 
quadrangle. The laminated clays that have been briefly described 
as forming the terraces along the Hudson, between Fishkill Land- 
ing and New Hamburg, and on the west bank at Roseton and 
Danskammer, are worked on extensive scales (see plates 25 and 26). 


108 NEW YORK STATE MUSEUM 


These beds form only a part, but are perhaps as important as any, 
of the valued clays of the Hudson valley. 

These deposits are very similar in appearance. The lower por- 
tions are usually bluish and the upper yellowish in color. The 
laminated character is best shown in the upper layers. Thin laminae 
of sand occasionally appear, in some places forming such proportion 
of the masses as to require no admixtures of that material in the 
process of brick manufacture. The coarser sandy material over- 
lying the clay, when screened, furnishes sufficient quantities of sand 
when that is required, which is usually the case on account of the 
purity of the clay. 

The chemical composition of the clay at Roseton is given from 
the following analysis :+ 


SiO) is aan OuMemichin you atadesuae oops dass HysQ0502c 0225 2 55.00 
Al,O l 

Bree Uo s'y b aleyalie salen silo ighotetdhete dove dud bao ent etal thn ee, AO ea al 
Fe,O, 34-54 
CEO PPE aE Rr a en eta nS ERE PE A SSS bo od boo can 5.33 
INT: Dieses a atoe Sas sve ghe tvlice wh gishe alsin shaver ates Besa tase: aoe Oe aS 3.43 
La@ 
Na,0 he sacsid SW icin cee hatste aha. sala GIS a ine eae Rc 0.48 
Combined H,O) oe 
ee eee Ae wSs bre bteahe Saud pela Oates et ene Oe : 

100.00 


Both the blue and yellow clays are calcareous and effervesce 
with acid. They have been used as marls on account of their lime 
content. The yellow color is due to oxidation. The clays are used 
entirely for brick. 

Clay deposits also occur at Arlington, a mile east of Poughkeepsie, 
and are used for brick. The clay which is fairly abundant along 
the banks of Casper creek in the neighborhood of Arlington is 
covered with some sod, but is easily exposed by stripping this off. 
Yellow clay is underlain by blue clay. 

It seems possible that the deposits at Arlington were accumulated 
in lacustrine waters, perhaps impounded by stagnant ice at the 
mouth of Casper creek. The kames (see plate 21) that now lie 
near the mouth of the creek may have been left by the melting of 
such a mass of ice. 

Limestone quarries. Quarries have been opened at places in 
the limestone strips of the Wappinger creek belt. The largest of 
these is Stoneco quarry, operated by the Clinton Point Stone Com- 


1 Ries, N. Y. State Mus. Bul. 35, 1906, p. 381. 


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GEOLOGY OF THE POUGHKEEPSIE QUADRANGLE IOQ 


pany. The rock is somewhat silicious and dolomitic, as the follow- 
_ ing analysis' shows: 


NO NMOS St csisr eee Si) osc, sea Som ries SARL AE, sialmraca Ghatnaihan mote gr tte oh bialen aR 29.07 


ANNUITY,“ og. 5 -RG STR LS Reo CPR UO es or 2RB3 
PE ig tgt Mm Oxi CIMT perce. cera nce cee as termites) oie chalice oe at arn oe ensue Mae 47 
SACD, o a.6 odes ee Aer COS ROP SER Area Ear OR Un Ras PU EERE oes SUE Re RAR 10.17 


Another quarry has been opened on the west bank of the Hudson 
in the southwestern extension of the western strip of the Wap- 
pinger creek belt, about three-quarters of a mile south of Marl- 
boro station. This is commonly known as Kerr’s quarry. A 
considerable enterprise was apparently projected and was in active 
operation up to the season of 1909. During that season work was 
suspended. 

The limestone near New Hamburg was burned for lime in earlier 
years. Its silica and magnesia content would necessitate lean 
returns. 

At Ruppert’s quarry near Poughkeepsie the ecg is burned 
for lime for private use. 

The Fishkill limestones were used for lime in earlier days, and 
also as a flux in the operation of the Hopewell furnace a generation 
ago. 

Limonite deposits. Limonite, or brown hematite, beds belong- 
ing to a fairly well-defined belt of these deposits cccur two miles 
south of Fishkill Village and near Shenandoah. A small quantity 
of ore was taken from the former in 1885. The Shenandoah mine 
was abandoned in 1879 cn account of the small quantity of ore. 

The question of the origin of these deposits was discussed by 
Professor Dana.t According to his view, during the transition from 
the limestone-making epoch to that of terrigenous sediments, iron- 
bearing waters were washed into restricted basins and in the course 
of time the calcareous and magnesian material became changed to 
ferriferous rock. In some cases pure iron carbonate was probably 
formed. The general magnesian character of the limestone was 
taken as good evidence of the confined character of the basins re- 
ceiving the additions of iron-bearing solutions. 

Kaolin. A residual deposit of kaolinite derived from the 
disintegration of a feldspathic rock occurs near Shenandoah, and 


*N. Y. State Mus. 51st Rep’t 2:434; also N. Y. State Mus. Bul. 44, p. 779. 
2 Amer. Jour. Sci., Ser. 3. 1884. 28:398-400. 


IIo NEW YORK STATE MUSEUM 


is known as Fowler’s kaolin mine. The material at present is taken 
_ out on a small scale and sold principally for stove cement. 

Molding sands. Molding sand is dug in large quantities a 
short distance back from the Hudson, near the mouth of Casper 
creek and two miles north of that place, and is hauled to docks at 
these places for shipment. 


BIBLIOGRAPHY 


The following list of references has been selected from a large num- 
ber of contributions which have been consulted in the preparation of 
this paper: 

1809 Maclure, William. Observations on the Geology of the United 
States. Amer. Phil. Soc. Trans. p. 411-28, with map. 

1810 Akerly, Samuel. A Geological Account of Dutchess County in 
New York. Bruce’s Amer. Mineralogical Journal, 1:11-16. 

1817. Maclure, William. Second Edition of the Observations. Trans. 
Amer. Phil. Soc. 

1820 Akerly, Samuel. An Essay on the Geology of the Hudson 
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seen. 

1820 Eaton, Amos. An index to the Geology of the Northern States, 
Swe. 

1822 Eaton, Amos. An Outline of the Geology of the Highlands on 
the River Hudson. Amer. Jour. Sci. 5:231-35. 

1822 Pierce, James. Geology, Mineralogy, Scenery etc. of the High- 
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1824 Dewey, Chester. A Sketch of the Geology and Mineralogy of 
the Western Part of Massachusetts. Amer. Jour. Sci. v. 8, with map. 
1828 Eaton, Amos. Geological Nomenclature in North America. 

1832 Mather, W. W. Notices of the Geology of the Highlands of 
New York. Amer. Jour. Sci. 21:97-99. 

1837. Mather, W. W. First Annual Report on the Geology of the First 
District of the State of New York. 

1838 Mather, W. W. Second Annual Report on the Geology of the 
First District. 

1839 Mather, W. W. Third Annual Report on the Geology of the 
First District. 

1840 Mather, W. W. Fourth Annual Report on the Geology of the 
First District. 

1841 Mather, W. W.- Fifth Annual Report on the Geology of the 
First District. 

1841 Hitchcock, E. Final Report on the Geology of Massachusetts. 
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1842 Emmons, E. Geology of the Second District of the State of 
New York. 

1843 Mather, W. W. Geology of the First District. Final Report. 


ee 


GEOLOGY OF THE POUGHKEEPSIE QUADRANGLE Ii it 


1845 Adams, C. B. First Annual Report on the Geology of Vermont. 

1846 Emmons, E. Agriculture of New York. 1:45-112. 

1846 Emmons, E. Remarks on the Taconic System. Amer. Quar. 
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MoOeedunt, bh. 8. On the Taconic System. Proc: A. A, AjyS: 
4:202-4. 

1853-54 Logan, Sir William. Reports of Progress of the Geological 
Survey of Canada. 

1854 Hunt, T. S. On Some of the Crystalline Limestones of North 
America. Amer. Jour. Sci, Ser. 2. 18:193-200. 

1855 Logan, Sir William. Report of Progress of the Geological 
Survey of Canada. 

1855 Emmons, E. American Geology. Albany, 1855. 

1856 Logan, Siv William. Report of Progress of the Geological 
Survey of Canada. 

1859 Salter, J. W. Canadian Organic Remains, Geological Survey of 
Canada. Decade I. 

1861 Barrande, J. Documents Anciens et Noveaux sur la Primor- 
diale et le Systéme Taconique en Amerique. Bul. Soc. Géol. de France. 
2:18. 

1861 Hitchcock, E. & others. Report on the Geology of Vermont. 
v. I, with map. 

1861 Hunt, T. S. On the Taconic System of Dr Emmons. Amer. 
Jour. Sci., Ser. 2. 32:427-30. 

1862 Hunt, T. S. On the Taconic System of Dr Emmons. Amer. 
Joum Set, Sir 2h Sees =o. 

1864 Hall, James & Logan, Sir W. On the Geology of Eastern New 
York. Reported by T. S. Hunt. Amer. Jour. Sci. Ser. 2. 34:96-07. 

1868 Cook, George H. Geology of New Jersey. 

1872 Dana, J. D. Green Mountain Geology. On the Quartzite. 
MMT OUT SCL, Ser 3. 3170-0: 

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quag, Dutchess co., N. Y. Amer. Jour. Sci. Ser. 3. 3 :253-56. 

1872 Dana, J. D. What is True Taconic? Amer. Nat. 6:197-99. 

1072.) Dana, J. DS) On the true faconie Amer Jour Sei, Ser 3: 
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1872 Dana, J. D. On the Quartzite, Limestone, and Associated 
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% dy INO, Usa: 

1673 Dana, J. D: Idem. Amer. Jour. Sci. v. 5, Jan. and Feb. 1873. 

1873 Dana, J. D. Slates of the Taconic Mountains of the Age of 
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1877. Dana, J. D. On the Relations of the Geology of Vermont to 
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1877 Hall, James. Note upon the History and Value of the term 
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A. A. A. S., 26:259-65. See also Amer. Jour. Sci., Ser. 3. .16:482. 


112 NEW YORK STATE MUSEUM 


1879 Dale, T. N. On the Age of the Clay-slates and Grits of Pough- 
ike@peie, Avance, omit, SCi., Sei, 3 17S 7=50- 

1879 Dana, J. D. On the Hudson River Age of the Taconic Schists 
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1879 Gerard, W. R. The Hudson Group at Poughkeepsie. Amer. 
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1879 Whitfield, R. P. Discovery of Specimens of Maclurea Magna 
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ANANSI, | OWligs Silky Seity Ba wise27 

1879 Dwight, W. B. On Some Recent Explorations in the Wap- 
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1879 Dwight, W. B. The Results of Some Recent Paleontological 
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1880 Dwight, W. B. Recent Explorations in the Wappinger Valley 
Limestone of Dutchess Co. New York. Number 2, Calciferous as well 
as Trenton Fossils in the Wappinger Limestone at Rochdale and a 
Trenton Locality at Newburgh, New York. Amer. Jour. Sei; Seng 
19:50-54. 

1880 Dana, J. D. Note on the Age of the Green Mountains. Amer. 
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1880 Dana, J. D. Geological Relations of the Limestone Belts of 
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1881 Dana, J. D. Idem. v. 21, June 1881, and vy. 22, 7Anceande@cir 
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1881 Dwight, W. B. Further Discovery of Fossils in the Wappin- 
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1882 Dana, J. D. Geological Age of the Taconic System. Quar. 
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1883 Booth, H. & Lown, C. Discovery of Utica Slate Graptolites 
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1883 Hunt, T. S. A Historical Account of the Taconic Question in 
Geology, with a Discussion of the Relations of the Taconic Series to 
the Older Crystalline and to the Cambrian Rocks. Roy. Soc. of Canada 
ileernss | SEG) ak 227-7 Os 

1883 Dwight, W. B. Recent Investigations and Paleontological 
Discoveries in the Wappinger Limestone of Dutchess and Neighboring 
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1884 Dwight, W. B. Recent Explorations in the Wappinger Valley 
Limestone of Dutchess Co., New York: Number 4, Description of 
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1884 Dwight, W. B. Report of Progress in Geological Investiga- 
tion in the Vicinity of Poughkeepsie. Vassar Bros. Inst. Trans. 
AeA Se : 

1884 Hall, James. Hudson River Age of the Taconic Slates, written 
by. Joa De Amer ourmocts Sehis..weo at 2 


GEOLOGY OF THE POUGHKEEPSIE QUADRANGLE 113 


1884 Dana, J. D. The Southward Ending of a Great Synclinal in 
fhembaconic Range. Amer. Jour. Sci. Vol: 28. Oct. 1884. 

1884 Ford, S. W. Note on the Discovery of Primordial Fossils in 
the Town of Stuyvesant, Columbia Co., New York. Amer. Jour. Sci. 
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1884 Ford, S. W. Age of Rocks near Schodack Landing. Amer. 
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1885 Ford, S. W. Note on the Age of the Slates and Arenaceous 
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1885 Dana, J. D. On Taconic Rocks and Stratigraphy, with a Geo- 
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and June, 1885. 

1885 Darton, N. H. Fossils in the Hudson River Slates of the 
Soumerimumants On |Orance Cony iNa Mee Amery  Jiourm Sciy Ser) 3: 
30:452-54. 

1886 Dana, J. D. Berkshire Geology. A paper read before the 
Berkshire Historical and Scientific Society at Pittsfield, Mass., Feb. 
5, 1885. 

1886 Smock, J. C. A Geological Reconnaissance in the Crystalline 
Rock Region of Dutchess, Putnam and Westchester Counties, N. Y. 
‘Thirty-ninth Ann. Report State Museum of Nat. Hist. p. 166-85. 

1886 Bishop, I. P. On Certain Fossiliferous Limestones of Colum- 
bia Co., N. Y., and their Relations to the Hudson River Shales and the 
DLaconic System. Amer. Jour. Sci, Ser. 3. 32:438-41. 

1886 Ford, S. W., & Dwight, W. B. Preliminary Report upon Fossils 
Obtained in 1885 from Metamorphic Limestones of the Taconic Series of 
Emmons at Canaan, N. Y. Amer. Jour. Sci. Vol. 31. April 1886. 

1886 Dana, J. D. On Lower Silurian Fossils from a Limestone of 
the Original Taconic of Emmons. Amer. Jour. Sci. Vol. 21. April 1886. 

1886 Dwight, W. B. Recent Explorations in the Wappinger Valley 
Limestone of Dutchess Co., N. Y. Number 5. Discovery of Fossilifer- 
Puc eotsdant Strata. at Poughkeepsie. Amer... Jour, Sci. + Ser. 3. 
Rien eee Seee also, Mranss \Wassam Bros. sinst.. 4:i3:0-46, under! title 
“Primoidial Rocks of the Wappinger Valley Limestone,” 1887. 

1886 Dwight, W. B. The Peculiar Structure of Clark’s Clay Beds 
near Newbursh, N. Y.. Vassar Bros. Inst. Trans. 3:86-87. Abstract 
PAMimMetr) OMG. Sei, Set 3) 82224142: 

1886 Darton, N. H. The Taconic Controversy in a Nut Shell. 
SSGlemeey || 7:76.70: 

1887 Dwight, W. B. Paleontological Observations of the Taconic 
Limestones of Canaan, Columbia Co., N. Y. Abstract, Amer. Nat. 
Oe270-7 Ie 

1887 Dwight, W. B. Primordial rocks of the Wappinger Valley Lime- 
stones and Associated Strata. Trans. Vassar Bros. Inst. 4:206-14. Also 
Amer, Olin, Stil, Sem 6. Sea 7 =. 

1887 Walcott, C. D. The Taconic System. Amer. Jour. Sci., Ser. 3. 
33:153-54. 

1887 Dwight, W. B. Recent Explorations in the Wappinger Valley 
‘Limestone of Dutchess Co., N. Y. Number 6. Discovery of Additional 


Ii4. NEW YORK STATE MUSEUM 


Fossiliferous Potsdam Strata and pre-Potsdam Strata of the Olenellus 
Group near Poughkeepsie, N. Y. Amer. Jour. Sci., Ser. 3. 34:28=32: 

1887 Dana, J. D. On Taconic Rocks and Stratigraphy, Amer: 
Jour Se, Wol, 24 Ayomil 1837, 

1887 Walcott, C. D. Fauna of the “Upper Taconic” of Emmons 
ia WWalsinvaciom (Cos, IN, Wo Amen, Jowir, Sek 8, aslen87ao0. 

1887. Newberry, J. S. Middle Cambrian Trilobites from near Pough- 
keepsie, Wrans: N.Y. Acad: of Sct. (6:113) See also; py accu © neane 
Taconic System of Emmons.” 

1888 Walcott, C. D. Discovery of Fossils in the “ Lower Faconic ” 
Or Bimmmoms, Iroc, A, A AS, Boni 12, 

1888 Walcott, C. D. Synopsis of Conclusions on the Taconic of 
Emmons. Amér. Geol. 2:215-10. 

1888 Dana, J. D. A Brief History of Taconic Ideas. Amer. Jour. 
Scie pVioll son Deer 1ese! ; 

1888 Walcott, C. D. The Taconic System of Emmons and the Use 
of the Name Taconic in Geologic Nomenclature. Amer. Jour. Sci., Ser. 3. 
35:229-42, 307-27, 394-401. 

1888 Kemp, J. F. Dikes of the Hudson River Highlands. Amer. 
Nat. 22:691-08. 

1889 Smock, J. C. First Report on the Iron Mines and Iron Ore 
Deposits in the State of New York. N. Y. State Mus. Bul. 7. 

1889. Nason, F. L. Geological Studies of the Archaean Rocks. 
Geol. Sur. of N. J. Annual Report of State Geologist. 

1889 Dwight, W. B. Recent Explorations in the Wappinger Valley 
Limestones and Other Formations of Dutchess Co., N. Y. Amer. 
Jour. Sci. Vol. 38. Aug. 1880. 

1889 Upham, W. Glaciation of Mountains in New England and 
New York. Amer. Geol. 4:165-74, 205-16. 

1890 Hunt, T. S. Geological History of the Quebec Group. Amer. 
Geol. 5:212-25. 

1890 Ami, H. M. On the Geology of Quebec and Environs. Bul. 
Geol. Soc. of Amer. 2:478-502. 

1890 Walcott, C. D. Value of the Term. “The Hudson River Group” in 
Geological Nomenclature. Bul. Geol. Soc. of Amer. 1:335-57. 

1890 Merrill, F. J. H. Metamorphic Strata of Southeastern New 
York. Amer. Jour. Sci. 39:383. 

1890 Nason, F. L. The Post-Archaean Age of the White Limestones. 
of Sussex Co., N. J. Annual Report of State Geologist of N. J. 

1891 Walcott, C. D. Overlap Relations at the Base of the Paleozoics 
in the Northern Appalachians. Bul. Geol. Soc. Amer. 2:163-64. 

1891 Merrill, F. J. H. On the Post-Glacial History of the Hudson 
River Valley. Amer. Jour. Sci, Ser. 3. 41 :460-66. 

1892 Walcott, C. D. Correlation Papers, Cambrian. Bull Us se 
(Gi, Ss Sits 

1892 Wan Hise, C. R. Correlation Papers, Pre-Cambrian. Bul. U. S. 
Gy Ss 80; : 

1892 Emerson, B. K. Outlines of the Geology of the Green: Moun- 
tain Region in Massachusetts. U. S. G. S., Geol. Atlas of the U. S., 
Hawley Sheet, preliminary edition. 


GEOLOGY OF THE POUGHKEEPSIE QUADRANGLE I15 


1893 Dale, T. N. The Rensselaer Grit Plateau in New York. Thir- 
feenta Annual Report U.S: GS: pt 2. p. 207-337. 

_ 1894 Pumpelly, Dale & Wolff. Geology of the Green Mountains in 
' Massachusetts. Monograph of the U. S. G. S. 23. 

- 1899 Merrill, F. J. H. The Geology of the Crystalline Rocks of 
-Southeastern New York. Fifteenth Annual Report N. Y. State Mus. 
1:21-31, appendix A. 

-1899 Dale, T. N. The Slate Belt of Eastern New York and Western 
» Vermont. Nineteenth Annual Report U. S. G. S. pt. 3. p. 150-306. 

: 1899 Emerson, B. K. The Geology of Eastern Berkshire Co., Mass. 
mee S..G. S. 150. 

1899 Clarke, J. M. Guide to the Fossiliferous Rocks of New York 
State. Handbook 15. 

1900 Dwight, W. B. Fort Cassin Beds in the Calciferous Limestone 
of Dutchess Co., N.Y. Bul. Geol. Soc. of Amer. vol. 12. 

1900 Kemp, J. F. Precambrian Sediments in the Adirondacks. 
Vice-Presidential address before the section of geology and geography. 
Proc, A. Aa A; S: vol. 49, 1900. 

1900 Ries, H. Clays of New York; Their Properties and Uses. N. Y. 
State Mus. Bul. 35. 

1900 Weller, Stuart. Description of Cambrian Trilobites from New 
| jersey, with Notes on the Age of the Magnesian Limestone Series. 
Annual Report Geol. Sur. of N. J. for 1800. 

1901 Ruedemann, R. Hudson River Beds near Albany and Their 
Taxonomic Equivalents. N. Y. State Mus. Bul. a2. 

1901 Ruedemann, R. Trenton Conglomerate of Rysedorph Hill, 
Rensselaer Co., N. Y., and its Fauna. N. Y. State Mus. Bul. 49. p. 1-114. 

Toor Ries, H. Lime and Cement Industries of New York. N. Y. 
State Mus. Bul. 44. 

1902 Ulrich, E. O. & Schuchert, Chas. Paleozoic Seas and Barriers 
in Eastern North America. N. Y. State Mus. Bul. 52. p. 633-63. 

1902 Dale, T. N. Structural Details in the Green Mountain Region 
and in Eastern New York. Bul. U.S. G. S. 1095. 

1904 Peet, C. E. Glacial and Post-Glacial History of the Hudson and 
Champlain Valleys. Jour. of Geol. 12:415-69, 617-60. 

1905 Woodworth, J. B. Ancient Water Levels of the Champlain and 
Hudson Valleys. N. Y. State Mus. Bul. 84. p. 65-265. 

iOos a eOalewaneN haconic Physiography. | Bolly U.S: G'S, 272: 

1905 Grabau, A. W. Types of Sedimentary Overlap. Geol. Soc. of 
Amer. Bul. 17:567-636. 

1906 Berkey, C. P. Paleogeography of St Peter Time. Geol. Soc. 
of Amer Bul. 17:220-50. 

1906 Rice, W. N., & Gregory, H. E. Manual of the Geology of Con- 
necticut. Conn. Geol. and Nat. Hist. Sur. Bul. 6. 

1906 Rice, W. N., & Gregory, H. E. Manual of the Geology of Con- 
necticut. Bul. 6. Conn. Geol. and Nat. Hist. Sur. 

1907 Berkey, C. P. Structural and Stratigraphic Features of the 
Basal Gneisses of the Highlands. N. Y. State Mus. Bul. 107. 

1908 Kemp, J. F. Buried Channels Beneath the Hudson and its 
Tributaries. Amer. Jour. Sci., Ser. 4.  26:301-23. 


116 NEW YORK STATE MUSEUM 


1908 Bayley, W. S. Preliminary Account of the Geology of the 
Highlands of New Jersey. Science. May 8, 1908. p. 722. 

1908 Berkey, C. P. Limestones Interbedded with Fordham Gneiss in 
New York (Citys Abstract) ) Science, —Decy 25. 1008s spose: 

1909 Wan Hise, C. R., & Leith, C. K. Pre-Cambrian Geology of North 
Asinernca, Iai, Us S. GS. a6o. 

1909 Gordon, C. E. Some Geological Problems. Science. June 4, 
1909. p. 901-3. 

1909 Gordon, C. E. Preliminary Report on the Geology of the Pough- 
keepsie Quadrangle. ‘Twenty-eighth Report of the New York State 
Geoloris,  IWlitls, IB, 1345 jo, was), 

1909 Bascom, F. Pre-Triassic Metamorphic Rocks of the Piedmont 
Plateau Area in the Norristown, Germantown, Chester and Philadelphia 
Quadrangles. Geol. Atlas of the United States. Philadelphia Folio 162. 

1910 Gordon, C. E. Further Report on the Geology of the Pough- 
keepsie Quadrangle. N. Y. State Mus. Bul. 140. p. 16-20: 


. Fr 


' Adams, C. B., cited, 111. 
_ Agricultural industry, 106. 


Akerly, Samuel, cited, 110. 
Ami, H. M., cited, 114. 
Amphigraptus divergens, &4. 
Arlington, 108. 

Arthursburg, 8, 71, 87-88, 92. 
Asaphus vetustus, 61. 


Bald hill, 7, 14, 78, 99. 

Bald hill granite gneiss, II, 14-16, 
HOw20-2022. 34, AO. 

Barnegate limestone, see Wappinger 
limestone. 

Barrande, J., cited, 111. 

Bascom, F., cited, 116. 

Bastite, 39. 

Bathyurus, 60. 
crotalifrons, 61. 
taurifrons, 61. 

Bayley, W. S., cited, 116. 

Beekmantown formation, 56, 59-61, 
@2) 64) 71, 72=75. 

Bellerophon bilobatus, 83. 

Berkey, Charles P., map prepared 
under direction of, 5; acknowledg- 
ments to, 5; cited, 36, 115, 116. 

Bibliography, 110-16. 

@tike.) LOM Z1O) 22) 23,027) 20.) 37. 
32. 

Bishop, I Py citéd, 113. 

Bonney hill, 8o. 


“Booth, Henry, mentioned, 83, 84: 


cited, 112. 
Breakneck mountain ridge, 7. 
Brick industries, 107. 
Briggs, mentioned, 61. 
Brinckerhoff, 9, 76. 
Buried river channels, 97. 
Bythotrephis antiquata, 60. 
subnodosa, 83. 


| Calcareous shale, 47. 


Calciferous-Rochdale group, 59. 


117 


INDEX 


Calymmene senaria, 67. 

Camelot, 52, 104. 

Carthage Landing, 102. 

Casper creek, 8, 9, 98, 104, 105, 108. 

Ceraurus pleurexanthemus, €7. 

Chaetetes compacta, 62. 
lycoperdon, 67. 

var. ramosa, 60. 
tenuissima, 61, 62. 

Chestnut ridge, 8. 

Chilorite, 18; 30, 31. 

Clarke, John M., acknowledgments 
LOWS) Guoteds SOs ciredy 50, 62) 105: 
83, 115. 

Clarke, W. R., mentioned, 30. 

Clays, 107-8. 

Climactograptus bicornis, 84. 

Clinton Point Stone Company, 52, 
53- 

Clove creek, 9. 

Conglomerates, summary of feat- 
ures shown by, 91-92. 

Conocephalites, see Ptychoparia. 

Cook, George H., cited, 111. 

Cushing, H. P., mentioned, 56. 

Cyrtoceras, 60. 
dactyloides, 61. 
microscopicum, 61. 
vassarina, 61. 


Dairy farming, 106. 

Dale, T. Nelson, 
cited, 83, 112, IS. 

Dalmanella testudinaria, 67, 83, 84. 

Dana, J. D., mentioned, 10; cited, 
AS, AO, OS, GS, MoO, Wi, WA) we, 
IIA. 

Danskammer, 55, 97, 98, IOI, 102, 107. 

Darton, N. H., cited, 113. 

Dewey, Chester, cited, 110. 

Dicellocephalus, 40. 

Dicellograptus divaricatus, 84. 

Dichograptus, see Dicellograptus; 
Dicranograptus. 


mentioned, 10; 


118 


Dicranograptus furcatus, 84. 

Didymograptus sagittarius, 84. 

Diorite, 15. 

Diplograptus marcedus, 84. 
pristis, 84. 

Drainage, 8, 105; preglacial, history 
of, 96-09. 

Drumlins, 100. 

Dutchess county limestone, 61. 

Dwight, W. B., mentioned, Io, 56, 63, 
65; cited, 48, 40, 56, 50, 60, 61, 62, 
Ue, GG}, etal ne 


East Fishkill, 77. 

East Fishkill Hook, 13, 24, 43, 104. 

Eaton, Amos, cited, 110. 

Echinoencrinites anatiformis, 62. 

Economic geology, 106-10. 

Emerson, B. K., mentioned, 39; cited, 
PLAN Tce 

Emmons, E., cited, 26, I10, III. 

Epidote, 27, 28. 

Erosion, 99-100; postglacial, 104-5. 

Escharapora recta, 61. 


Fallkill creek, 8, 9, 105. 

Faults, 13; in the gneisses, 33; Wap- 
pinger creek belt, 65-70; limestones, 
within the Hudson River forma- 
tion, 87-06. 

Inellalsoaim U6. WA, WS, Ba 27, Be 

Fishkill creek, 8, 85, 98, 103, 104, 105. 

Fishkill Landing, 6. 

Fishkill limestone, 26, 34, 48, 70-82, 
106, 109; peculiar lithic variations 
within, 76. 

Fishkill mountains, 7, 9; kame de- 
posits, 104; gneisses, 9, II, 18-25; 
gneisses, summary of microscopic 
characters, 30-33. 

Fishkill village, 77, 70, 90, 103. 

Fly mountain, It. 

Ford, S. W., cited, 113. 

Fordham gneiss, 37; of New York 
city, 36. 

Fossils, from quartzite and overlying 
limestone, 44-46. 

Freedom Plains, 95, 100. 

Fruit growing, 107. 


NEW YORK STATE MUSEUM 


Gayhead, 77. 

Geologic work, previous, 10. 

Geology, general, 9. 

Georgian formation, 72. 

Gerard, W. R., cited, 112. 

Glacial geology, 99-100. 

Glenham, 79, 85, 104. 

Glenham belt, 11, 18, 25-27, 33, 34, 
78. 

Gneisses, of the Fishkill mountains, 
Q, 11, 18-25, 30-33); Precambricsens 
petrography, 14-18; micaceous, 17; 
eastern 24-25; inliers, 25; sum- 
mary of microscopic characters, 
30-33; faults in, 33; summary and 
conclusions, 35-360; relations to 
quartzite, 47. 

Gordon, C, E., cited, 116. 

Grabau, A. W., map prepared under 
direction of, 5; cited, 64, 115; men- 
tioned, 80. 

Granite of Shenandoah mountain, 
24. 

Graptolithus, see Amphigraptus. 

Gregory, H. E., cited, 115. 

Groveville, 25. 


Hall, James, mentioned, 10; cited, 
AS, WU, Wi. 

Hematite, 30, 100. 

Highlands, 7, 36, 81, 99, 106. 

Highlands gneiss, 33. 

Hitchcock, E., cited, 110, 111. 

Holopea, 60. 

Honness spur, see Mount Honness 
spur. 

Hook district, 23-24. 

Hook spur, 14, 35, 43. 

Hopewell, 9, 71, 74. 

Hopewell Junction, 8, 80, 103. 

Hiornblende, 15, 16, 47,922) gouscu 
32, 38, 39. 

Hornblende gneisses, 16-17. 

Hortontown, 24, 25, 36, 42, 47. 

Hortontown basic eruptive rocks, 
37-39. 

Hortontown hornblende, 11. 

Hudson gorge, depth near Storm 
King, 7. 


Hudson River formation, faulted 
limestone, 87-06. 

_ Hudson River slate group, 11, 82-96. 
BHunt, T. S., cited, 111, 112, 114. 


_ Hyolithellus micans, 46. 


Ice sheet, retreat of, 100-4. 
- Illaenus crassicauda, 62, 67. 
Illinois mountain, 7, 83, 93, 106. 


Jackson creek, 8. 
Johnsville, 104. 


Kame deposits, 104. 

Kaolin deposits, 25, 100. 

Kemp, J. F., map prepared under 
direction of, 5; acknowledgments 
Owns). Cited: 7, 00, 100, TTA, 115. 


Lagrangeville, 95. 
Land forms, 105-0. 
Weitz. cited, 116, 


Leptaena (Plectambonites) sericea, 
61, 83, 84. 

Limestone, 47; faulted, 87-96; quar- 
ries, 108-9. See also Fishkill 
limestone. 


Limonite deposits, 100. 
Lingulella, see Obolella. 
Lingulepis acuminata, 40. 
minima, 40. 
pinniformis, 49, 50, 51, 55, 50, 61. 
Lituites, 60. 
Logan, Sir William, cited, 26, 111; 
mentioned, Io. 
Looking Rock, 7. 
Lower Cambric (Georgian) forma- 
tion, 72. 
Lown, C., mentioned, 84; cited, 112. 
Lowville, 65. 


Maclure, William, cited, 110. 

Maclurea magna, 56. 
sordida, 60, 74. 

Miaemeribe,| 155.10, 17, 1G, 21 24.30; 
S132, 372, 13: 

Manchester Bridge, 103. 

Marlboro, 55, 83, 101, 109. 

Marlboro mountain, 7. 


INDEX TO GEOLOGY OF POUGHKEEPSIE QUADRANGLE 


T19 


Mather, W. W., cited, 10, 26, 48, 61, 
83, I10. 

Matteawan, 6, 9, 12, 18-19, 30, 39, 72, 
78, 85, 95- 

Matteawan inliers, 26, 28-30, 34. 

Merrill, F. J. H., cited, 114, 115. 

Micaceous gneisses, 17. 

Microcline, 15, 17, 18, 31. 

Molding sands, 110. 

Monograptus, see 

Nemagraptus. 

Moore’s Mill, 88-80. 

Mount Beacon, 20. 

Mount Beacon brook section, 19-20, 
Ge, 83, 

Mount Honness, 7, 41, 99, 104. 

Mount Honness spur, 7, 14, 21-23, 
34, 82. 

Murchisonia gracilis, 60. 

Muscovite, 18, 31. 


Didymograptus ; 


Nason, F. L., cited, 114. 

Nemagraptus gracilis, 84. 

New Hamburg, 8, 48, 64, 97, 101, 102, 
109. 

Newberry, J. S., cited, 114. 


Obolella, 46. 

nana, 49. 

(Lingulella) prima, 49. 
Old Hopewell, 74, 105. 
Olenellus thompsoni, 46. 
Oncoceras vassiforme, 61. 
Ophileta, 6o. 

EOmmpevez, FO, CO, 7a, 7S, 77 

complanata, 60, 74. 

levata, 60, 74. 

sordida, 60, © 
Orthis, 50. 

lynx, 67. 

pectinella, 61, 67, 83. 

testudinaria, 61, 83, 84. 

tricenaria, 61. 
Orthoceras apissiseptum, 61. 

henrietta, 61. 

primigenium, 60. 
Orthocerata, 60. 
Orthoclase, 15, 16, 18, 31. 
Ostracod, 67. © 


120 


Peet, C. E., cited, 102, 115. 

Pegg’s Point, 97, 99. 

Petraia corniculum, 62. 

Petrographic character of the rock, 
influence of, 100. 

Petrography of the gneisses, 14-18. 

Phacops sp., 67. 

Pierce, James, cited, 110. 

Plagioclase, 15, 16, 18, 23, 31. 

Platyceras, 40. 

Platynotus trentonensis, 67. 

Pleasant Valley, 8, 50, 63, 91; lime- 
stone masses east of, 80. 

Plectambonites sericeus, 67, 83, 84. 
See also Leptaena. 

Pleurotomaria, 60. 

Postglacial erosion, 104-5. 

Potsdam formation, 49-51, 50, 64, 
100. 

Poughkeepsie, 6, 99, 109. 

Poughquag quartzite, Il, 39-47. 

Precambric gneisses, II. 

Preglacial history of drainage, 95- 
99. 

Ptilodictya acuta, 61. 

Ptychaspis, 40. 

Ptychoparia (Conocephalites), 4o. 
Spe: 
calcifera, 40. 
saratogensis, 4O. 

Pumpelly, cited, 115. 

Pyrite, 38. 

Pyroxene, 38. 


Ouartz, 15; 16; 17; 18,423, 27, 31, 32. 

Quartzite, 37, 38, 39; basal, 30-47: 
near Rochdale, 86. See also 
Poughquag quartzite. 


Receptaculites, 61. 

Red slates, 85. 

Rice, W. N., cited, 115. 

Ries, H., cited, 108, 115. 

Rochdale, 8, 57, 50, 60, 62, 63, 64, 86, 
Olay 10K, 

Roseton, 101, 102; clays, 107, 108. 

Ruedemann, R., cited, 65, 115. 


Salter, J. W., cited, ITT. 
Schuchert, Charles, cited, 115. 


NEW YORK STATE MUSEUM 


Sericite, 23, 3I. 

Serpentine, 38, 30. 

Shenandoah, 25, 100. 

Shenandoah mountain, 7, 13, 24, 35, 
42, 99. 

Shenandoah mountain granite, II, 
17-18. 

late formation, 85, 96. 

smock, J. C., cited, 11, 26) )1n3) ime 

Soils, 107. 

Solenopora compacta, 50, 51, 52, 62,, 
63, (67; 08,75, 1 7G..0m 

Sprout creek, 8, 88. 

Stoneco, 52, 55, 50. 

Stoneco quarry, 108. 

Storm King, 97, 08. 

Stormville, 80. 

Stratigraphical table, 11. 

Streptelasma sp., 67. 

Stromatocerium, 49. 

Stromatopora compacta, 62. 

Strophomena alternata, 61, 67, 75, 
83. 

Swartoutville, 73, 76, 84, 92. 

Sylvan lake, 8. 


Terraces, I0!. 

Tertiary uplift, 97. 

Tetradium cellulosum, 62, 65. 

Titanite, 31. 

Titusville, 68. 

Topography, 7. 

Trenton formation, 51-56, 50, 61-62, 
OS) ZL Seen 

Triplecia, 59. 


Ulrich, E. O., mentioned, 50; cited, 
Tie. 
Upham, W., cited, 114. 


Valleys of the Tertiary cycle, 96. 

Van Hise, C. R., cited, 104, 116: 

Vly mountain, 11, 26, 27, 30, 33, 40, 
i 72s 


Walcott, C. D., cited, 56) 1igeaaae 

Wappinger creek, 8, 98, 103, 104, 105. 

Wappinger creek belt, western strip, 
48-56; central strip, 57-65; faulted 
blocks, 65-70; limestone quarries, 
108. 


INDEX TO GEOLOGY OF POUGHKEEPSIE QUADRANGLE I2t 


Wappinger Falls, 6, 8. 


~Wappinger limestones, 10, 11, 48, 95. 


—-. Ss eS —-—S.-. 


Weller, Stuart, cited, 115. 


West Fishkill Hook, 13, 34, 44, 72, 
104. 


Whaley pond, 8. 


Whitfield, R. P., cited, 56, 84, 112. 


~Whortlekill creek, 8. 


Wilsey’s quarry, 78. 

Wisconsin ice sheet, retreat of, 
100-4. 

Wolcottville, 78, 85. 

Wolff, cited, 115. 

Woodworth, J. B., cited, ror, 115. 


ZICEONS. LS Owe. ale 


New York State Education Department 
New York State Museum 


Joun M. CrarkeE, Director 
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Bulletins are grouped in the list on the following pages according to divisions. 
The divisions to which bulletins belong are as follows: 


i Zoology 5t Zoology tor Paleontology 

2 Botany 52 Paleontology to2 Economic Geology 
3 Economic Geology 53 Entomology 103 Entomology 

4 Mineralogy 54 Botany 104 « 

5 Entomology 55 Archeology ro5 Botany 

6 2 56 Geology 106 Geology 

7 Economic Geology 57 Entomology 107 

8 Botany 58 Mineralogy r0o8 Archeology 

9 Zoology 59 Entomology tog Entomology 

to Economic Geology 60 Zoology IIo o 

Ir e 61 Economic Geology rrr Geology 

12 i 62 Miscellaneous 112 Economic Geology 
13 Entomology 63 Paleontology 113. Archeology 

14 Geology 64 Entomolog r114 Paleontology 

15 Economic Geology 65 Paleontology r15 Geology 

16 Archeology f 66 Miscellaneous 116 Botany 

17 Economic Geology 67 Botany r17 Archeology 

18 Archeology 68 Entomology 118 Paleontology 

19 Geology 69 Paleontology r19 Economic Geology 
20 Entomology vo Mineralogy I20 ft 

21 Geology 71 Zoology t2z Director's report for 1907 
22 Archeology 2 Entomology 122 Botany 

23 Entomology 473 Archeology 123 Economic Geology 
24 ie 44 Entomology 124 Entomology 

25 Botany 75 Botany 125 Archeology 

26 Entomology 46 Entomology 126 Geology 

27 f 44 Geology 127 cc 

28 Botany 478 Archeology 128 Paleontology 

29 Zoology 79 Entomology 129 Entomology 

30 Economic Geology 80 Paleontology 130 Zoology 

31 Entomology 81 a 131 Botany 

32 Archeology 82 e x32 Economic Geology 
33 Zoology 83 Geology 133 Director's report for 1908 
34 Paleontology 84 ue 134 Entomology 
35 Economic Geology 85 Economic Geology 135 Geology 

36 Entomology 86 Entomology 136 Entomology 

37 87 Archeology 137 Geology 

38 Zoology 88 Zoology 138 & 

39 Paleontology 89 Archeology 139 Botany 

4o Zoology 90 Paleontology r40 Director’s report for 1909 
4t Archeology 91 Zoology r4t Entomology 

42 Paleontology 92 Paleontology 142 Economic geology 
43 Zoology 93 Economic Geology L143 a 

44 Economic Geology 94 Botany 144 Archeology 

45 Paleontology 95 Geology 145 Geology 

46 Entomology 96 i 146 « 

47 97 Entomology 147 Entomology 

48 Geology 98 Mineralogy 148 Geology 

49 Paleontology 99 Paleontology 


50 Archeology I0o Economic Geology 


MUSEUM PUBLICATIONS 


_ Bulletins are also found with the annual reports of the museum as follows: 


Bulletin Report Bulletin Report Bulletin Report Bulletin Report 
2-15 48,Vv.1 72 57,Vv.1, Pt 2 102 59, Vv. I 134 62, Vv. 2 
16,17 50,V.1 73 57, Vv. 2 103-5 59,V.2 135 63, V.1 
18,19 VEL 74 57, V.1I, pt 2 106 FO, We oe 136 63, V.2 
20-25 RO OaV ak 75 57, Vv. 2 107 60, Vv. 2 137 (ep Wo 28 
26-31 Bei5 We a 76 Ber Ly Doz) LOS 60, Vv.3 138 63, Vv. 1 
2-34 54,V.1 77 Bi Me Dey Db Le LOO LO) OO vend I39 63, Vv. 2 
35,36 54, Vv. 2 78 S75 We 2 III GON. 2 I4o 63, V.1r 
37-44 IS Ap Vices 79 BF Ws Hy Ie Be 60, Vv. 1 I4I 63,V. 2 
45-48 54, Vv. 4 80 iin We thy JOG oe 1S} 60, V. 3 142 63h ava 2 
49-54 Sn Wo 81,82 58, V.3 II4 60, Vv. I 143 Ostnvens 
55 56, Vv. 4 83,84 58, Vv. 1 II5 60, Vv. 2 
56 56, Vv. 1 5 58, v. 2 Ir6 60, Vv. 1 Memoir 
57 56, Vv. 3 80 58, Vv. 5 Il7 60, Vv. 3 2 49, V.3 
58 56, Vv. I 87-89 58,V.4 118 60, Vv. I 3,4 5SShve 2 
59,60 56,Vv.3 90 58, v. 3 REO=BH Ot, Wo % 5,6 Si) Wo 3 
61 56, Vv. I 91 58,Vv.4 eel22 61, Vv. 2 7 57,V-4 
62 56,Vv.4 92 Re Wa 123 61, V.I 8, pt 1 59,V.3 
63 56, v. 2 93 58, Vv. 2 124 Gravel 2 3 De 2 59, V. 4 
64 56, Vv. 3 94 58,v.4 I25 62, V.3 @ JOE 60, Vv. 4 
65 56, Vv. 2 95,96 Bist, WW Te 126-28 62,Vv.1 9, Dt 2 62,V.4 
66,67 56,Vv.4 97 58, Vv. 5 129 62, Vv. 2 IO 60, Vv. 5 
68 5 wo 6) 98,99 SO, We 2 130 62,V.3 II Or, We 3 
69 56, Vv. 2 Io0o 59, Vv. I LZil 13/2) O2eavia 2 I2 63, V.3 
e770), 7 ain We 8p JO a8 Beeps 59, Vv. 2 133 62,V.1 13 63, V. 4 


The figures at the beginning of each entry in the following list indicate its number as a 
museum bulletin. 


Geology. 14 Kemp, J. F. Geology of Moriah and Westport Townships, 
Essex Co. N. Y., with notes on the iron mines. 38p. il. 7pl. 2 maps. 
Sept. 1895. Free. 

Ig Merrill, F. J. H. Guide to the Study of the Geological Collections of 
the New York State Museum. 164p. 119pl. map. Nov. 1898. Out of print. 

21 Kemp, J. F. Geology of the Lake Placid Region. 24p. 1p!. map. Sept. 
1898. Free. 

48 Woodworth, J. B. Pleistocene Geology of Nassau County and Borough 
om Oucens, | )59p. il, Spl, map. Dee: 190r. 2'5¢. 

56 Merrill, F. J. H. Description of the State Geologic Map of 1901. 4ap. 

ionmaps, tab: Nov. t902. Free. 

77 Cushing, H. P. Geology of the Vicinity of Little Falls, Herkimer Co. 
Sopsileaspe 2 maps. Jian 1905.) 30c: 

83 Woodworth, J. B. Pleistocene Geology of the Mooers Quadrangle. 62p. 
25pl. map. June 1905. 25¢. 

84 Ancient Water Levels of the Champlain and Hudson Valleys. 206p. 
(erplecomaps. july ro85.) 5c: 4 

95 Cushing, H. P. Geology cf the Northern Adirondack Region. 188p. 
Hyple gaps. § sept. L905. 30C. 

96 Ogilvie, I. H. Geology of the Paradox Lake Quadrangle. s5,p. il. r7pl. 
map. Dec. 1905. 30C. ; 

106 Fairchild, H. L. Glacial Waters in the Erie Basin. 88p. 14pl. 9 maps. 
Feb. 1907. Out of print. 

to7 Woodworth, J. B.; Hartnagel, C. A.; Whitlock, H. P.; Hudson, G. H.; 
Clarke, J. M.; White, David & Berkev, C. P. Geological Papers. 388p. 
s4pl. map. May 1907. 9go¢, cloth. 


Contents: Woodworth, J. B. Postglacial Faults of Eastern New York. 

Hartnagel, C. A. Stratigraphic Relations of the Oneida Conglomerate. 

Upper Siluric and Lower Devonic Formations of the Skunnemunk Mountain Region~ 

Whitlock, H. P. Minerals from Lyon Mountain, Clinton Co. 

Hudson, G. H. On Some Pelmatozoa from the Chazy Limestone of New York. 

Clarke, J. M. Some New Devonic Fossils. 

An Interesting Style of Sand-filled Vein. 

Eurypterus Shales of the Shawangunk Mountains in Eastern New York. 

White, David. A Remarkable Fossil Tree Trunk from the Middle Devonic of New York. 

Berkey, C. P. Structural and Stratigraphic Features of the Basal Gneisses of the High- 
lands. 


air Fairchild, H. L. Drumlins of New York. 6op. 28pl. 19 maps. July 
— 1907. Out of print. 

‘mrs Cushing, H. P. Geology of the Long Lake Quadrangle. 88p. 2opl. 
_ map. Sept. 1907. Out of print. 


NEW YORK STATE EDUCATION DEPARTMENT 


126 Miller, W. lps Geology of the Remsen Quadrangle. s54p. il. rrpl. map. 
Jan. 1909. 25 | 

127 Fairchild, re L. Glacial Waters in Central New York. 64p. 27pl. 15 
maps. Mar. 1909. 40C. | 

135 Miller, W. J. Geology of the Port Leyden Quadrangle, Lewis County, 
N.WYe) 62 ps ale ai pliimalp. aan.) voor sca5c: 

137 Luther, D. D. Geology of the Auburn-Genoa Quadrangles. 36p. map. 
Weve, TO)IO., Ae. 

138 Kemp, J. F. & Ruedemann, Rudolf. Geology of the Elizabethtown 
and Port Henry Quadrangles. 176p. il. zopl. 3 maps. Apr. 1910. 4o0¢. 

145 Cushing, H. P.; Fairchild, H. L.; Ruedemann, Rudolf & Smyth, C. H. 
Geology of the Thousand Islands Region. t1g4p. il. 62pl.6 maps. Dec. 
ONO) WEISS 

146 “Berkey, C. P. Geologic Features and Problems of the New York City 
(Catskill) Aqueduct. 286p. il. 38pl. maps. Feb. r911._ 75c; cloth, $1. 

148 Gordon, C. E. Geology of the Poughkeepsie Quadrangle. 122p. il. 
AjOky saa AjO)5 — YAOI WO) — BOD 

Luther, D. D. Geology of the Honeoye-Wayland Quadrangles. Im press. 


Economic geology. 3 Smock, J. C. Building Stone in the State of New 
York. «i54p. Mar. 1888. Out of print. 

7 First Report on the Iron Mines and Iron Ore Districts in the State 
of New York. 78p. map. June 1889. Out of print. 

10 Building Stone in New York. 210p. map, tab. Sept. 1890. 4oc. 

iz Merrill, F. J. H. Salt and Gypsum Industries of New York. og 4p. 12pl. 
2maps, 11 tab. Apr. 1893. [soc] 

I2 Ries, Heinrich. Clay Industries of New York. 174p. 1pl.il.map. Mar. 
1895. 30C. 

15 Merrill, F. J. H. Mineral Resources of New York. 240p. 2 maps. 
Sept. 1895. [soc] 

Road Materials and Road Building in New York. 52p. ra4pl. 
2 maps: w Oct ao 74) tye 

30 Orton, Edward. Petroleum and Natural Gas in New York. 136p. il. 
3 maps. Nov. 1899. 15¢. 

35 Ries, Heinrich. Clays of New York; their Properties and Uses. 456p. 
t4opl. map. June 1900. Out of print. 

Lime and Cement Industries of New York; Eckel, E. C. Chapters 
on the Cement Industry. 332p. 1o1pl. 2 maps. Dec. 1901. 85c, cloth. 

61 Dickinson, H. T. Quarries of Bluestone and Other Sandstones in New 
Vork i14p. copie 2omaps.) Mar. 90g. mage. 

85 Rafter, G. W. Hydrology of New York State. gop. il. 44pl. 5 maps. 
May 1905. $1.50, cloth. 

93 Newland, D. H. Mining and Quarry Industry of New York. 78p. 
July 1905. Out of print. 

too McCourt, W. E. Fire Tests of Some New York Building Stones. 4op. 
26pl. Feb. 1906. 5c. 

to2 Newland, D. H. Mining and Quarry Industry of New York 1905. 
162p. June 1906. 25¢. 

112 Mining and Quarry Industry of New York 1906. 82p. July 
1907. Out of print. 

& Kemp, J. F. Geology of the Adirondack Magnetic Iron Ores 
with a Report on the Mineville-Port Henry Mine Group. 184p. 14pl. 
SJ imo, yore, TOS, BEC 

120 Newland, D H. Mining and Quarry Industry of New York 1907. 8ap. 
July 1908. Out of print. 

123 & Hartnagel, C. A. Iron Ores of the Clinton Formation in New 
York State. 6p. il. 14pl. 3 maps. Nov. 1908. 25¢. 

132 Newland, D.H. Mining and Quarry Industry of New York 1908. 8p. 
July 1909. 15¢. 

142 Mining and Quarry Industry of New York for 1909. go8p. Aug. 
TO LORS C. : 

143 Gypsum Deposits of New York. g94p. zopl. 4 maps. Oct. 1910. 
Bsc: 

j 


17 


44 


MUSEUM PUBLICATIONS 


“Mineralogy. 4 Nason, F.L. Some New York Minerals and their Localities. 

meoop cpl Aug. 1888. Free. 

58 Whitlock, H. P. Guide to the Mineralogic Collections of the New York 

State Museum. sop. il. 39pl. 11 models. Sept. 1902. oc. 

70 New York Mineral Localities. tiop. Oct. 1903. 20¢c. 

98 —— Contributions from the Mineralogic Laboratory. 38p. 7pl. Dec. 

fm 1005. Out of print. 

Paleontology. 34 Cumings, E.R. Lower Silurian System of Eastern Mont- 
gomery County; Prosser, C. 5. Notes on the Stratigraphy of Mohawk 
Valley and Saratoga County, NE NOE 74 pe 14pliemaip ss May pool lmses 

39 Clarke, J. M. Simpson, G. B. & Loomis, F. B. Paleontologic Papers 1. 

E72 pail xople, |Oct. to00. 1c. 


Contents: Clarke, J. M. A Remarkable Occurrence of Orthoceras in the Oneonta Beds of 
the Ch2nango Valley, 5 

— Paropsonema eryptophya; a Peculiar Echinoderm from the Intumescens-zone 
(Portage Beds) of Western New York. 

—— Dictyonine Hexactinellid Sponges from the Upper Devonic of New York. 

—— The Water Biscuit of Squaw Island, Canandaigua Lake, N. Y. 

Simpson, G. B. Preliminary Descriptions of New Genera of Paleozoic Rugose Corals. 

Loomis, F. B. Siluric Fungi from Western New York. 


42 Ruedemann, Rudolf. Hudson River Beds near Albany and their Taxo- 
nomic Equivalents. THEO. Aol, majo, Aor, TOO, DBgZe, 

45 Grabau, A. W. Geology and Paleontology of Mineara Falls and Vicinity. 
2EGO, wl, neyo way, | yore, wee,  OFCs cloth, goc. 

49 Ruedemann, Rudolf; Chale. J. M. & Wood, Elvira. Paleontologic 
Papers 2. 240p. 13pl. Dec. 1901. Out of print. 
Contents: Ruedemann, Rudolf. Trenton Conglomerate of Rysedorph Hill. 


Clarke, J. M. Limestones of Central and Western New York Interbedded with Bitumi-« 
nous Shales of the Marcellus Stage. 

Wood, Elvira. Marcellus Limestones of Lancaster, Erie Co., N. Y. 

Clarke, J. M. New Agelacrinites. 

Value of Amnigenia as an Indicator of Fresh-water Deposits during the Devonic of 


New York, Ireland and the Rhineland. 


52 Clarke, J. M. Report of the State Paleontologist 1901. 28op. il. ropl. 
Mapm tabs july 1902: —40c. 

63 & Luther, D. D. Stratigraphy of Canandaigua and Naples Quad- 
fangles. 78p. map. June 1904. 25¢. 

65 Clarke, J. M. Catalogue of Type Specimens of Paleozoic Fossils in the 
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Report of the State Paleontologist 1903. 396p. 29pl. 2 maps. 
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81 & Luther, D. D. Watkins and Elmira Quadrangles. 32p. map. 
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82 Geologic Map of the Tully Quadrangle. 4op.map. Apr.1905. 20c. 

90 Ruedemann, Rudolf. Cephalopoda of Beekmantown and Chazy For- 
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92 Grabau, A. W. Guide to the Geology and Paleontology of the Schoharie 
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99 Luther, D. D. Geology of the Buffalo Quadrangle. 32p..map. May 
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114 Hartnagel, C. A. Geologic Map of the Rochester and Ontario Beach 
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118 Clarke, J. M. & Luther, D. D. Geologic Maps and Descriptions of the 
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128 Luther, D. D. Geology of the Geneva-Ovid Quadrangles. 44p. map. 
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Geology of the Phelps Quadrangle. In preparation. 

Whitnall, H. O. Geology of the Morrisville Quadrangle. Prepared. 


69 
80 


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Hopkins, T. C. Geology of the Syracuse Quadrangle. Prepared. 

Hudson, G. H. Geology of Valecour Island. In preparation. 

Zoology. 1 Marshall, W. B. Preliminary List of New York Unionidae. 
zop. Mar. 1892. Free. 

Beaks of Unionidae Inhabiting the Vicinity of Albany, N. Y. 3o0p. 
cpl. Aug: 1890; Free: 

29 Miller, GS, jr. Preliminary List of New York Mammals. r2ap. Oct. 

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33 ieee M.S. Check List of New York Birds. 224p. Apr. 1900. 25¢. 

38 | Miller, G. S. jr. Key to the Land Mammals of Northeastern North 
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40 Simpson, G. B. Anatomy and Physiology of Polygyra albolabris and 
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43 Keitoee! ae L. Clam and Scallop Industries of New York. get 2pl. 
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51 Eckel, E. C. & Paulmier, F.C. Catalogue of Reptiles and Baneicniene 
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Eckel, E. C. Serpents of Northeastern United States. 
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60 Bean, T. H. Catalogue of the Fishes of New York. 784p. Feb. 1903. 
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71 Kellogg, J. L. ees Habits and Growth of Venus mercenaria. 3op. 
4pl. Sept. 1903. 

88 Letson, Elizabeth ie Schock List of the Mollusca of New York. 11z6p. 
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QI Baier F. C. Higher Crustacea of New York City. 78p. il. June 
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130 Shufeldt, R. W. Osteology of Birds. 382p. il. 26pl. May 1909. Soc. 

Entomology. 5 Lintner, J. A. White Grub of the May Beetle. 34p. il. 

ov. 1888. Free. 

6 —— Cut-worms. 38p. il. Nov. 1888. Free. 

13 San José Scale and Some Destructive Insects of New York State. 
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20 Felt, E. P. Elm Leaf Beetle in New York State. 46p. il. spl. June 
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Supplement to r4th report of the State Entomologist. 
26 


Collection, Preservation and Distribution of New York Insects. 
S1OyO}, alle | Tayo, Tlevoyois.  Wehinete 
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31 15th Report of the State Entomologist 1899. 1328p. June 1goo. 


TAGs 
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37 —— Catalogue of Some of the More Important Injurious and Beneficial 
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46 —— Scale Insects of Importance and a List of the Species in New York 


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47 Needham, J. G. & Betten, Cornelius. Aquatic Insects in the Adiron- 
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53 Felt, E. P. r7th Report of Fie State Entomologist I90l,  232psqlNopie 
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68 Needham, J. G. G& others. Aquatic Insects in New York. B22 pases 
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76 Felt, E. P. xroth Report of the State Entomologist 1903. 150p. apl. 
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6 Control of Flies and Other Household Insects. s6p. il. Feb. 

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This is a revision of Bulletin 129 containing the more essential facts observed since 
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4 26th Report of the State Entomologist rg10. 182p. 3spl. il. Mar. 

IQIt. nes 

Sdham, |. G. Monograph on Stone Flies. In preparation. 

Botany. 2 Peck, C. H. Contributions to the Botany of the State of New 

5 York. 72p. 2pl. May 1887. Out of print. 

: Boleti of the United States. 98p. Sept. 1889. Out of print. 


25 Report of the State Botanist 1898. 76p. spl. Oct. 1899. Out of 
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sa Plants of North Elba. 206p. map. June 1899. 200. 

54. Report of the State Botanist 1901. 58p. 7pl. Nov. 1902. 40Cc. 

57 —— Report of the State Botanist 1902. 196p. spl. May 1903. soc. 

75 —— Report of the State Botanist 1903. op. 4pl. 1904. 4oc. 

D4 —— Report of the State Botanist 1904. 6op. topl. July 1905. 4oc. 

f05 —— Report of the State Botanist 1905. 3108p. r2pl. Aug. 1906. 50¢c. 

116 —— Report of the State Botanist 1906. 120p. 6pl. July 1907. 3sc. 

122 —— Report of the State Botanist 1907. 178p. spl. Aug. 1908. 4oc. 

131 —— Report of the State Botanist 1908. 202p. 4pl. July 1909. 40Cc. 


139 —— Report of the State Botanist 1909. 1316p. 1opl. May KO MOMs Ai Ce 
Archeology. 16 Beauchamp, W. M. Aboriginal Chipped Stone Implements 
| of New York. 86p. 23pl. Oct. 1897. asc. 

18 Polished Stone Articles Used by the New York Aborigines. IO4p. 
| abl Nev, 1807. 25¢; 


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25C. 


32 Aboriginal Occupation of New York. 1g0p. 16pl. 2 maps. Maz 

Ig00. 30C. 
Wampum and Shell Articles Used by New York Indians. 166; 
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Mae TOO2. FO: 


41 
50 


55 Metallic Implements of the New York Indians. g4p. 38pl. Jun 
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73 Metallic Ornaments of the New York Indians. r122p. 37pl. De 
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78 History of the New York Iroquois. 340p. 17pl. map. Feb. 190 
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87 Perch Lake Mounds. 84p.12pl. Apr. 1905. Out of print. 

89 Aboriginal Use of Wood in New York. t1o0p. 35pl. June 190 
35¢. 

i108 Aboriginal Place Names of New York. 336p. May 1907. 40 

Tere Civil, Religious and Mourning Councils and Ceremonies of Ado 


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117 Parker, A. C. An Erie Indian Village and Burial Site. 1ozp. 38p 
Dec. 1907. 30C. 

125 Converse, H. M. & Parker, A.C. Iroquois Myths and Legends. 196 
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144 Parker, A. C. Iroquois Uses of Maize and Other Food Plants. 120 
Bupl al.» NovewtoT0, &3oc: : 

Miscellaneous. Ms 1 (62) Merrill, F. J. H. Directory of Natural Histor 
Museums in United States and Canada. 236p. Apr. 1903. 30C. 

66 Ellis, Mary. Index to Publications of the New York State Natur 
History Survey and New York State Museum 1837-1902. 418p. Jun 
1903. 75¢, cloth. 

Museum memoirs 1889—date. 4to. 

t Beecher, C. E. & Clarke, J. M. Development of Some Silurian Brachi 
opoda. g6p. 8pl. Oct. 1889. $1. 

2 Hall, James & Clarke, J. M. Paleozoic Reticulate Sponges. 35op. il. 7op. 
1898. $2, cloth. 

3 Clarke, J. M. The Oriskany Fauna of Becraft Mountain, Columbia Co. 
INE) m2sp- sole Oct moco wm coe: 

4 Peck, C.H. N.Y. Edible Fungi, 1895-99. 106p.25pl. Nov. 1900. [$1.25 
This includes revised descriptions and illustrations of fungi reported in the 49th, 51st an 

52d reports of the State Botanist. 

5 Clarke, J. M. & Ruedemann, Rudolf. Guelph Formation and Fauna o 
New York State. ro6p. 21pl. July 1903. $1.50, cloth. | 

6 Clarke, J. M. Naples Fauna in Western New York. 268p. 26pl. map 
$2, cloth. 

7 Ruedemann, Rudolf. Graptolites of New York. Pt 1 Graptolites of th 
Lower Beds. 350p. 17pl. Feb. 1905. $1.50, cloth. | 

8 Felt, E. P. Insects Affecting Park and Woodland Trees. v.1. 460f 
il. 48pl. Feb. 1906. $2.50, cloth; v.2. 548p. il. 22pl. Feb. 1907. $2, cloth 

9 Clarke, J. M. Early Devonic of New York and Eastern North America 
Pt xr. 366p. il. yopl.5 maps. Mar. 1908. $2.50, cloth; Pt 2. 250p. il. 36p! 
4 maps. Sept. 1909. $2, cloth. 

to Eastman, C. R. The Devonic Fishes of the New York Formations 
236p. r5pl. 1907. $1.25, cloth. 

tr Ruedemann, Rudolf. Graptolites of New York. Pt 2 Graptolites o 
the Higher Beds. 584p. il. 2 tab. 3rpl. Apr. 1908. $2.50, cloth. 

12 Eaton, E. H. Birds of New York. v. 1. 5orp. il. 42pl. Apr. 19% 
$2, cloth; v. 2, in press. 

13 Whitlock,H.P. CalcitesofNew York. t1oop. il.27pl. Oct. 1910. $1, cloth 
Clarke, J. M. & Ruedemann, Rudolf. The Eurypterida of New York 
In press. 


MUSEUM PUBLICATIONS 


atural history of New York. 3ov. il. pl. maps. 4to. Albany 1842-94. 

IVISION 1 zooLOGY. De Kay, James E. Zoology of New York; or, The 
New York Fauna; comprising detailed descriptions of all the animals 
hitherto observed within the State of New York with brief notices of 
those occasionally found near its borders, and accompanied by appropri- 
ate illustrations. 5v.il.pl.maps. sq. 4to. Albany 1842-44. Out of print. 


Historical introduction to the series by Gov. W. H. Seward. 178p. 

-z ptr Mammalia. 131 + 46p. 33pl. 1842. 

300 copies with hand-colored plates. 

Bewpte Birds. 12+ 380p. ra4rpl. 1844. 

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- 3 pt3 Reptiles and Amphibia. 7+ 98p. pt4Fishes. 15 + 415p. 1842. 
pt 3-4 bound together. 


. 4 Plates to accompany v. 3. Reptiles and Amphibia. 23pl. Fishes. 
wopl. 1842. 


| 300 copies with hand-colored plates. 
- 5 pts Mollusca. 4+ 271p. gopl. pt6 Crustacea. jop.13pl. 1843-44 
' Hand-colored plates; pt5-6 bound together. 


IVISION 2 BOTANY. Torrey, John. Flora of the State of New York; com- 
prising full descriptions of all the indigenous and naturalized plants hith- 
_ erto discovered in the State, with remarks on their economical and medical 
_ properties. ev. il. pl. sq. 4to. Albany 1843. Oud of print. 

v. r Flora of the State of New York. 12+ 484p. 72pl. 1843. 


300 copies with hand-colored plates. 
vy. 2 Flora of the State of New York. 572p. 89pl. 1843. 
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DIVISION 3 MINERALOGY. Beck, Lewis C. Mineralogy of New York; com- 
prising detailed descriptions of the minerals hitherto found in the State 
of New York, and notices of their uses in the arts and agriculture. il. pl. 
sq. 4to. Albany 1842. Out of print. 


vy. 1 ptr Economical Mineralogy. pt2 Descriptive Mineralogy. 24 + 536p. 
1842. 


8 plates additional to those printed as part of the text. 


DIVISION 4 GEOLOGY. Mather, W. W.; Emmons, Ebenezer; Vanuxem, Lard- 
ner & Hall, James. Geology of New York. 4v. il. pl. sq. ato. Albany 
1842-43. Out of print. 

y. rptr Mather, W.W. First Geological District. 37 + 653p.46pl. 1843. 

v. 2 pt2 Emmons, Ebenezer. Second Geological District. 10 + 437p. 
t7pl. 1842. 

v. ee Vanuxem, Lardner. Third Geological District. 306p. 1842. 

v. 4 pt4 Hall, James. Fourth Geological District. 22 + 683p.  ropl. 
map. 1843. 


DIVISION 5 AGRICULTURE. Emmons, Ebenezer. Agriculture of New York; 
comprising an account of the classification, composition and distribution 
of the soils and rocks and the natural waters of the different geological 
formations, together with a condensed view of the meteorology and agri- 
cultural productions of the State. 5v. il. pl. sq. 4to. Albany 1846-54. 
Out of print. 

v. t Soils of the State, their Composition and Distribution. 11 + 371p. 21pl. 
1846. 

y. 2 Analysis of Soils, Plants, Cereals, etc. 8 + 343 + 46p. 42pl. 1849. 


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v. 5 Insects Injurious to Agriculture. 8+ 272p. sopl. 1854. 


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DIVISION 6 PALEONTOLOGY. Hall, James. Palaeontology of New York. 8y 
il. pl. sq. 4to. Albany 1847-94. Bound in cloth. “a 
v. 1 Organic Remains of the Lower Division of the New York System 
23 + 338p. oopl. 1847. Out of print. 
v. 2 Organic Remains of Lower Middle Division of the New York System 
8 + 362p. ro4pl. 1852. Out of print. | 
v. 3 Organic Remains of the Lower Helderberg Group and the Oriskant 
Sandstone. pti, text. 12+ 532p. 1859. [$3.50] | 
—— pt 2, 143pl. 1861. [$2.50] 
v. 4 Fossil Brachiopoda of the Upper Helderberg, Hamilton, Portage an 
Chemung Groups. 11 + 1+ 428p.69pl. 1867. $2.50. 
v. 5 pt 1 Lamellibranfchiata 1. Monomyaria of the Upper Helderberg 
Hamilton and Chemung Groups. 18 + 268p. 45pl. 1884. $2.50. 
Lamellibranchiata 2. Dimyaria of the Upper Helderberg, Ham 
ilton, Portage and Chemung Groups. 62 + 2903p. 5r1pl. 1885. $2.50 
pt 2 Gasteropoda, Pteropoda and Cephalopoda of the Upper Helder 
berg, Hamilton, Portage and Chemung Groups. 2v. 1879. v. 1, text 
I5) + 402p:3 v.2. t20pl.) $2.50 for 2 v. 
& Simpson, George B._ v. 6 Corals and Bryozoa of the Lower and Up 
per Helderberg and Hamilton Groups. 24 + 298p. 67pl. 1887. $2.50 
& Clarke, John M. v. 7 Trilobites and other Crustacea of the Oris 
kany, Upper Helderberg, Hamilton, Portage, Chemung and Catskil 
Groups. 64 + 236p.46pl. 1888. Cont. supplement tov. 5,pt2. Ptero 
poda, Cephalopoda and Annelida. 4z2p.18pl. 1888. $2.50. 
& Clarke, John M. v.8pti1 Introduction to the Study of the Gener 
of the Paleozoic Brachiopoda. 16 + 367p. 44pl. 1892. $2.50. 
& Clarke, John M. v.8 pt 2 Paleozoic Brachiopoda. 16 + 394p. 64pl 
1894. $2.50. 


Catalogue of the Cabinet of Natural History of the State of New York ane 
of the Historical and Antiquarian Collection annexed thereto. 242p. 8vo 


1853. 
Handbooks 1893-date. 


In quantities, 1 cent for each 16 pages or less. Single copies postpaid as below. 


New York State Museum. 52p. il. Free. 
Outlines, history and work of the museum with list of staff 1902. 
Paleontology. s12p. Free. 


Brief outline of State Museum work in paleontology under heads: Definition; Relation t¢ 
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Guide to Excursions in the Fossiliferous Rocks of New York. 1124p. Free 


Itineraries of 32 trips covering nearly the entire series of Paleozoic rocks, prepared specially 
‘f or the use of teachers and students desiring to acquaint themselves more intimately with the 
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Economic Geology. 44p. Free. 

Insecticides and Fungicides. 2op. Free. 

Classification of New York Series of Geologic Formations. 32p. Free. 


Geologic maps. Merrill, F. J. H. Economic and Geologic Map of the 
State of New York; issued as part of Museum bulletin 15 and 48th Musemi 
report, Vv. 1. 59x67cm. 1894. Scale 14 miles to 1 inch. 5c. ; 


x 


3 


MUSEUM PUBLICATIONS 


Map of the State of New York Showing the Location of Quarries of 

Stone Used for Building and Road Metal. Mus. Bul. 17. 1897. Free. 

Map of the State of New York Showing the Distribution of the Rocks 
Most Useful for Road Metal. Mus. Bul. 17. 1897. Free. 

—— Geologic Map of New York. t901. Scale 5 milesto1inch. In atlas 
jorm $3; mounted on rollers $5. Lower Hudson sheet 60c. 


The lower Hudson sheet, geologically colored. comprises Rockland, Orange, Dutchess, 
Putnam, Westchester, New York, Richmond, Kings, Queens and Nassau counties, and parts 
eS Sullivan, Ulster and Suffolk counties; also northeastern New Jersey and part of western 

Onnecticut. 


Map of New York Showing the Surface Configuration and Water Sheds. 

LOO cale 42 miles to x mech. “15. 

Map of the State of New York Showing the Location of its Economic 
Deposits. 1904. Scale-12 miles to 1 inch. 1r5c. 

Geologic maps on the United States Geological Survey topographic base. 
Scale 1 in. == 1 m. Those marked with an asterisk have also been pub- 
lished separately. 

*Albany county. Mus. Rep’t 49. v. 2. 1898. Out of print. 

_Area around Lake Placid. Mus. Bul. 21. 1898. 

Vicinity of Frankfort Hill [parts of Herkimer and Oneida counties]. Mus. 
Repitese, Vs I. 1809. 

Rockland county. State Geol. Rep’t 18. 1899. 

Amsterdam quadrangle. Mus. Bul. 34. 1900. 

*Parts of Albany and Rensselaer counties. Mus. Bul. 42. 1901. Free. 

*Niagara river. Mus. Bul. 45. 1901. 25¢. 

Part of Clinton county. State Geol. Rep’t 19. Igor. 

Oyster Bay and Hempstead quadrangles on Long Island. Mus. Bul. 48. 
Igol. 

Portions of Clinton and Essex counties. Mus. Bul. 52. 1902. 

Part of town of Northumberland, Saratoga co. State Geol. Rep’t 21. 1903. 

Union Springs, Cayuga county and vicinity. Mus. Bul. 69. 1903. 

*Olean quadrangle. Mus. Bul. 69. 1903. Free. 

*Becraft Mt with 2 sheets of sections. (Scale 1 in. 4m.) Mus. Bul. 69. 
1903. 20C. 

*Canandaigua-Naples quadrangles. Mus. Bul. 63. 1904. 20c. 

*Little Falls quadrangle. Mus. Bul. 77. 1905. Free. 

*Watkins-Elmira quadrangles. Mus. Bul. 81. 1905. 200. 

*Tully quadrangle. Mus. Bul. 82. 1905. Free. 

*Salamanca quadrangle. Mus. Bul. 80. 1905. Free. 

*Mooers quadrangle. Mus. Bul. 83. 1905. Free. 

*Buffalo quadrangle. Mus. Bul. 99. 1906. Free. 

*Penn Yan-Hammondsport quadrangles. Mus. Bul. ror. - 1906. 20¢. 

*Rochester and Ontario Beach quadrangles. Mus. Bul. 114. 200. 

*Long Lake quadrangle. Mus. Bul. 115. Free. 

*Nunda-Portage quadrangles. Mus. Bul. 118. 20¢. 

*Remsen quadransle. Mus. Bul. 126. 1908. Free. 

*Geneva-Ovid quadrangles. Mus. Bul. 128. 1909. 20¢. 

*Port Leyden quadrangle. Mus Bul. 135. s1g10. Free. 

*Auburn-Genoa quadrangles. Mus. Bul. 137. 1910. 200. 

*Blizabethtown and Port Henry quadrangles. Mus. Bul. 138. t1g1o. 15¢c. 

*Alexandria Bay quadrangle. Mus. Bul. 145. Free. 

*Cape Vincent quadrangle. Mus. Bul. 145. Free. 

*Clayton quadrangle. Mus. Bul. 145. Free. 

*Grindstone quadrangle. Mus. Bul. 145. Free. 

*Theresa quadrangle. Mus. Bul. 145. Free. 

*Poughkeepsie quadrangle, Mus. Bul. 148. Free. 


EDUCATION DEPARTMENT 


JOHN M, CLARKE 
STATE GROLOGIST 


UNIVERSITY OF THE STATE OF NEW YORK 


STATE MUSEUM 


(Rhinebeck) 
sz 


sae, 


BULLETIN 148 
POUGHKEEPSIE QUADRANGLE 


i 
yas 


on 


(West Point) 


Scale s=ko0 


4 4 2 n p Slomoters 


Contony interyal 20 thet 
Datum ws mean sea level. 


DMiles 


Geology by Clarence E. Gordon 


LEGEND 


+ 


“Hudson Riyer'' 
wroup: shales, slates, 
grits, conglomerates, 
and phyllites. 


Includes Trenton, 
Black River (Norman- 
skill) and probably 
Utica. 


“Wappinger” Dim e- 
stone: conglomeratic, 
Arenaceous, and luta- 
eeous siliceous and 
dolomitic limestones. 


Includes Georgian. 
Potsdam, Beekman- 
town and Trenton 


Basal (“Poughquag”) 
Quartzite: granular 
quartzite, occaslonally 
conglomeratic or 
shaly 


Georgian ) 

~ 
“Basal Gnetsses:" 
bornblendicand mica- 


ceous gneisses and al- 
tered derivatives, 


“Grenville” 


Pe | 
Important or consple- 
uous outcrops. 


Probable Faults 


Formation contacts: 
Interpretation left 
open; probably faulted 
in many cases; normal 
between quartzite and 
gnelss 


Quartzite at Rochdale 


R 
Red Shales 


F 
Fossil Localities 


ORDOVICIC 


CAMBRIC CAMBRIC AND 
ORDOVICIC 


PRE-CAMBRIC 


- ‘een myn ype = Syieft 


MANGES 19 Yu rt AERP R GAIN MAC YER anal AN RENE TIEL: VEN! eC AR MA 1 OI LAR 


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ALILSNI Saluvudit LIBRARIES SMITHSONIAN _INST 


NVINOSHHINS 


4 


INSTITUTION NOIL 


y ae 

by 

lip 
INSTITUTION NOIL 


Satyvagl 


NSTITUTION NOILNLILSNI NVINOSHLIWS S314 


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S3INVYGIT LIBRARIES SMITHSONIAN INSTI 


ARTES SMITHSONIAN 


Co | 
s’satuvuagl 


NVINOSHLINS S31YVYUSIT LI 


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