as.

»w York State Museum Bulletin

tion pending for admission as second-class matter at the Post Office at Albany, Nia,
under the act of August 24, I9I2

Published monthly

.82

FEBRUARY I, I916

ALBANY, N. Y. 5

New York State Museum

JOHN M. CLARKE, Director

GEOLOGY OF THE LAKE PLEASANT

QUADRANGLE, HAMILTON COUNTY, NEW YORK

WILLIAM J. MILLER

THE

Ms53r-Mr15-1500

UNIVERSITY OF THE STATE OF
1916

PAGE PAGE
General geography and geology.. ,7,|. Drainage...¢..5...)..0.. 6.00%. 61
meeramioric FOCKS .. 2... ..0.5.... Or IS Gla CIO ay 5 es OE ates Ae ibe 63
Paleozoic rock outliers.......... a2 “|, Stomengfarties is. GMa OT 71
ES RE ae eee Oey VEG ee A SCE eee POR 73
Summary of geologic and physio-

Mirage mistory al... .. Ble. 57
ALBANY

NEW YORK

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THE UNIVERSITY OF THE STATE OF NEW YORK —

Regents of the University
With years when terms expire

1926 PLINY T. Sexton LL.B. LL.D. Chancellor - Palen
1927 ALBERT VANDER VEER M.D. M.A. Ph.D. LL.D.

/

Vice Chancellor - - - — = — > T- Atbany
1922 CHESTER S.-Lorp M.A. LL. D. —- -—- e -— New York
1918 Witit1amM NottincHaM M.A. PhD. LL.D. — - Syracuse
1921 Francis M. CARPENTER -— —- — — — — — Mount Kisco
1923 ABRAM I. Erxus LL.B. D.C.L.- - - - - New York
1924 ADELBERT Moot LL.D. - - => - — — Buffalo
1925 CHARLES B. ALEXANDER M.A. LLB. LY:

Litt.D.. .-—°.-) He = ede
to190 JOHN MooRE - -— = - - = = =. -— Elmira.
1916 WALTER Guest Ketitoce B.A. - -, — — -— Ogdensburg

1917 (Vacant)
1920 (Vacant)

President of the University
and Commissioner of Education

Joun H. Finitey M.A. LL.D. LHD.

Deputy Commissioner and Assistant Commissioner
for Elementary Education

Mevaie E. Finecan M.A. Pd.D. mig Ly

Assistant Commissioner for Higher Education
Avucustus 8. Downinc M.A. L.H.D. LL.D.

Assistant Commissioner for Secondary Education

CHARLES F. WHEELOcK B.S. LL.D.

Director of State Library
James I. WyveEr, Jr, M.L.S.
Director of Science and State Museum
Joun M. Criarxe Ph.D. D.Sc. LL.D.
Chiefs and Directors of Divisions
Administration, GEoRGE M. WiLey M.A.
Agricultural and Industrial Education, ArtTHurR D. Deve
D.Sc., Director
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The University of the State of New York
Department of Science, February 23, 1915

Dr John H. Finley
President of the University

Sir; I transmit to you herewith the manuscript of a report on
The Geology of the Lake Pleasant Quadrangle, Hamilton County,
New York, prepared by Dr William J. Miller, and recommend its
publication as a bulletin of the State Museum.

Very respectfully
Joun M. CLARKE
Director

THE UNIVERSITY OF THE STATE OF NEW YORK
OFFICE OF' THE PRESIDENT

Approved for publication this 27th day of February 1915

President of the Unversity

New York State Museum Bulletin

Application pending for admission as second-class matter at the Post Office at Albany, N. Y.,
under the act of August 24, 1912

Published monthly

No. 182 ALBANY, N. Y. FEBRUARY, I9I6

New York State Museum

Joun M. CrarKke, Director

GEOLOGY OF THE LAKE PLEASANT QUADRANGLE,
HAMILTON COUNTY, NEW YORK

By Witt1AM J. MILLER

GENERAL GEOGRAPHY AND GEOLOGY

The area covered by the Lake Pleasant quadrangle (see map in
pocket of back cover) lies in the south-central portion of the Adiron-
dack region and wholly within southeastern Hamilton county. It
comprises an area of 216 square miles and is bounded by latitude
Nees-427 15" and 42° 30° and longitude Ines 74°15’ and. 74° 307.
The only villages are Wells, Lake Pleasant, Gilmantown, Benson,
and Benson Center. In most respects the region is typically Adiron-
dack in character, being rugged, densely wooded, sparsely settled,
and with few traveled roads. In fact, an area of fully 125 square
miles, comprising the southwestern portion of the quadrangle and
immediately adjoining territory, is unusually difficult of access,
being entirely devoid of traveled road or permanent residence. The
difficulties of doing detailed geological work in such a region are
impossible of appreciation by the uninitiated.

The main road from Northville to Wells, Speculator, and Lake
Pleasant is much traveled, especially during the summer season,
there being many summer resorts around Sacandaga lake and Lake
Pleasant. These, and the nearby Piseco lake, are the three largest
lakes in the southern Adirondacks.

All the drainage of the quadrangle passes into the Sacandaga river
which pursues a very circuitous course to the Hudson river at
Luzerne in Warren county. The main river drains Sacandaga lake
and Lake Pleasant and flows southward along the eastern side of
the quadrangle, being joined by the West Branch Sacandaga river,
which flows eastward across the middle of the quadrangle.

Altitudes vary from about 800 feet, where the Sacandaga river

8 NEW YORK STATE MUSEUM
leaves the map, to the summit of Hamilton mountain, whose alti-
tude is 3250 feet. The Hamilton-Swart mountain mass is the
largest and highest of the whole area. It is 5 miles long, 2 miles
wide, and has several peaks whose elevations range from 2000 to
3250 feet. Next in order comes the Three Ponds-Blue Ridge
mountain mass some 4 or 5 miles long, 2 or 3 miles wide, and with
several peaks ranging in altitude from 2800 to 3000 feet. Specu-
lator mountain, with an altitude of 2973, stands out prominently in
the northern part of the quadrangle. In the southwest, the Moose-
North Branch mountain mass shows altitudes from 2500 to 2800
feet. In the southeast, the Cathead mountain ridge rises to 2427
feet. Just west of Wells, the Mount Rouge-Dunham ridge stands
out very prominently as viewed from the east across the valley
(see plate 9). This ridge has a number of peaks reaching alti-
tudes from 2117 to 2646 feet. These and many other prominent
ridges trend from north-south to northeast-southwest due to
faulting.

From the geological standpoint the features of principal interest
are: the variety of Precambric rocks; the two important Paleozoic
rock outliers; the dissection of the region by numerous faults; and
the glacial phenomena.

The oldest rocks are members of the Grenville series which are
classed with the most ancient known rocks in the crust of the earth.
They are chiefly highly metamorphosed stratified rocks, and are
much less abundantly developed here than is usual in the Adiron-
dacks.

A small area of anorthosite-gabbro in the northeastern corner
of the quadrangle is probably of the same age as with the great
body of anorthosite in Essex county.

Next in age come various phases of the syenite-granite series.
These include augite and hornblende syenite to diorite, granitic
syenite, granite, and granite porphyry. These have all been intruded
into the Grenville and hence are younger though also metamor-
phosed. They are by far the most abundant rocks of the quadrangle.

Gabbro of the usual Adirondack sort occurs at several places.
Diabase, in the form of a few small dikes, is the youngest of the
Precambric rocks. Both gabbro and diabase are here less common
than in the eastern Adirondack region.

The Paleozoic rocks are wholly confined to the outliers in the
valleys at Wells and near Hope. Cambro-Ordovicic strata, includ-
ing Potsdam sandstone, Theresa sandstone and dolomite, Little

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GEOLOGY OF LAKE PLEASANT QUADRANGLE 9

Falls dolomite, Black River limestone (Lowville), Trenton lime-
stone, and Canajoharie (Trenton) shale are all represented.

The whole region of the quadrangle has been literally cut to
pieces by numerous normal faults, the fault ridges and blocks form-
ing the dominant features of the topography.

This region, in common with most of the rest of the State, was
buried under the great ice sheet of the Glacial (Pleistocene) epoch,
so that all the ordinary glacial phenomena may be observed.
Glacial deposits are widespread, the more important valleys usually
containing heavy glacial lake and morainic deposits.

The following papers contain statements which bear more or
less directly upon the geology of the quadrangle:

Darton, N. H. Geology of the Mohawk Valley. 18th Annual
Rep’t N. Y. State Geol. for 1893, p. 608-9.

Emmons, E. Geology of the Second District, 1842, p. 417.

Kemp, J. F. Physiography of the Eastern Adirondacks in the
Cambrian and Ordovician Periods. Geol. Soc. Am. Bul. 8,
p. 408-12.

Kemp, J. F., Newland, D. H., & Hill, B. F. Preliminary Report
on the Geology of Hamilton, Warren, and Washington Counties.
18th Annual Rep’t N. Y. State Geol., p. 134-62.

Miller, W. J. Early Paleozoic Physiography of the Southern
Adirondacks. N. Y. State Mus. Bul. 164, 1912, p. 80-94.

The Geological History of New York State. N. Y.
State Mus. Bul. 168, 1913, p. 42-43.

Ruedemann, R. Additional Note on the Ocean Current in the

Utica Epoch.. Am. Geol., Feb. 18g8, p. 75-81.

PRECAMBRIC ROCKS
Grenville series

So far as known, these Precambric rocks are to be classed with
the oldest formation in the crust of the earth. They represent a
thickness of thousands of feet of sedimentary rocks now highly
metamorphosed and crystallized so that much of the original sedi-
mentary character has been obliterated. The sedimentary character
is best shown by the repeated and rapid alternations of bands or
layers of distinctly different composition; the presence of such
rocks as crystalline limestone and quartzite; and the presence of
scattering flakes of graphite. These are the usual characteristics
of the Grenville throughout the Adirondack region and they are well
exhibited within the Lake Pleasant quadrangle.

As regards areal extent, however, the Grenville of the quadrangle

IO NEW YORK STATE MUSEUM

is considerably less than usual in the Adirondacks, there being only
about 14 square miles shown as such on the accompanying geologic
map. Besides this there must be added a few square miles of Gren-
ville represented in the mixed gneiss areas and as nonmappable
scattering inclusions throughout the great intrusives. The Grenville
is scattered over the quadrangle in masses ranging in size from very
small inclusions to a belt over 9 miles long. Almost invariably these
inclusions or belts lie parallel to the foliation of the inclosing igneous
rocks, with the foliation of the Grenville and inclosing rocks also
practically always parallel.

The largest Grenville area, extending from Wallace mountain
to Loomis pond, is remarkable because of its narrowness combined
with so great a width. It strikes due east and west 9% miles, or
three-fourths of the distance across the quadrangle, while its width
scarcely exceeds I mile at any place. Its westward extension beyond
the map limits is not known. There are many good outcrops
throughout the area, but more especially on Wallace, Three Ponds,
and Silver Lake mountains and from Loomis pond eastward. for
2 miles. In general the rocks are of two types, namely, gray to
nearly white, feldspar-quartz-garnet gneisses and quartzites, the
gray gneisses sometimes carrying sillimanite or graphite. All these
rock types are more or less interbedded. In thin-section the typical
light gneiss shows the following mineral percentages: orthoclase
62; microperthite 10; oligoclase 5; quartz 15; garnet (clear pink)
18; biotite 1; and small amounts of zircon and titanite. The
graphitic gneisses are similar except for lower feldspar and higher
garnet content, and a few per cent each of sillimanite and graphite
with usually a little pyrite. The typical quartzites contain 85 to
go per cent quartz; a few per cent each of hypersthene and biotite;
and smaller amounts of magnetite, sillimanite, and apatite. Quart-
zites are best seen in exposures on the north face of Silver Lake
mountain, the top of Three Ponds mountain, and at the west base
of Wallace mountain. Great ledges of the light, feldspar-garnet
gneisses constitute the upper two-thirds of Wallace mountain, par-
ticularly on the west side, where the beds lie nearly horizontal and
rest directly upon quartzite. Other good ledges of the feldspar-
garnet rocks occur at The Notch and on the north shore of Loomis
pond. The best outcrops of the graphitic rocks were found near the
north base of Silver Lake mountain. Throughout this long Gren-
ville area the dips are southward usually 40 to 50 degrees, though
in Wallace mountain it is only 1o degrees. Thus a thickness of at
least a few thousand feet of Grenville must be shown. It should

GEOLOGY OF LAKE PLEASANT QUADRANGLE Il

be clearly understood that this Grenville area, like most of the
others, is not always sharply separated from the inclosing rocks,
there frequently being so-called mixed gneisses along the borders.

The nine lenslike inclusions of Grenville shown in the southern
one-third of the quadrangle have strikes parallel and rocks similar
to those of the large area just described. These inclusions are
certainly only smaller fragments of the Grenville caught up in
the invading magma. Besides these, many small unmappable
inclusions were found and doubtless others were undiscovered in
this very rough country.

In the second largest Grenville area, which occupies a little over
2 square miles northeast of Wells, outcrops are scarce except in its
northern portion. Along each river, about one-fourth to one-half
of a mile above their confluence, are big ledges of Grenville white
gneiss which in thin-section shows the following mineral percent-
ages: feldspars (orthoclase, microcline, microperthite and oligo-
clase) 60; quartz 37; small, clear-red garnets 2; and muscovite I.
The limited exposures in the southern half of the area indicate the
prevalence of a light-gray feldspar gneiss much like that just de-
scribed but with no garnets and with tiny mica flakes making up
several per cent of the rock. Judging by its general appearance,
banded structure, variableness, and close association with limestone
in at least one place, this rock is quite certainly Grenville. This
white gneiss, as well as certain others of the quadrangle, is almost
identical in composition with that very recently regarded as of
igneous origin by Cushing?! in the Saratoga Springs region and by
him somewhat doubtfully called “Laurentian” granite. The field
relations and character of the white gneiss of the Lake Pleasant
region do not favor its igneous origin. No pegmatitic phases of the
white gneiss were there noted. Furthermore, as is pointed out in
the discussion of the granites, there are considerable areas of reddish
granites within the quadrangle whose color, field relations (includ-
ing long, narrow, amphibolite inclusions), etc. are almost precisely
like the so-called “ Laurentian” granite of the Thousand Islands
district, but the writer does not believe that both these red granites
and the white gneisses can possibly be of the same age and origin
within the Lake Pleasant quadrangle.

Four outcrops of limestone occur in the white gneiss area just
described. The largest, about 100 feet long, is associated with the
white gneiss and lies in the stream bed one-fourth of a mile above

1N. Y. State Mus. Bul. 169, 1914, p. 21-25.

I2 NEW YORK STATE MUSEUM

the mouth of the brook which drains Dunning pond. A similar
though smaller outcrop lies one-fourth of a mile still tarther up the
same stream, while a third exposure occurs near the road one-half
of a mile southwest of the mouth of this stream. All this limestone
is coarse to medium-grained, pure calcitic except for a few tiny
flakes of phlogopite or graphite in some beds. A medium-grained,
greenish-gray limestone outcrops in the road nearly 2 miles north-
east of Wells (see map). This contains numerous small, greenish
pyroxene crystals and occasional quartz grains.

In the Benson Center Grenville area the rocks are mostly medium-
grained, light to dark, distinctly banded, feldspar-quartz-biotite-
garnet gneisses, but these are frequently intimately shot through by
small amounts of granite or syenite, especially toward the north
where they pass into typical mixed gneisses.

In the Grenville area lying from 1% to 2 miles northeast of
Guideboard hill, the rock is largely Grenville dark, hornblende-
garnet gneiss with some wide bands or belts of quartzite.and a little
feldspar-quartz-biotite gneiss.

Due north of Guideboard hill the Grenville along the main road
is a gray, feldspar-hornblende-garnet gneiss, while in the northern
portion of the same area the rocks are chiefly light, feldspar-quartz
gneisses associated with quartzitic and biotitic gneisses.

The Grenville just west of Echo lake is but the southern end of
a considerable area of dark, hornblende-feldspar-garnet gneiss much
like that so commonly associated with limestone in the North Creek
quadrangle. Farther northward, limestone actually occurs with
this hornblende gneiss but none was seen within the map limits. A
few rods west of the road and near the map edge, a single ledge of
rusty looking graphitic gneiss was noted.

The small Grenville inclusions mapped on the west shore of
Sacandaga lake; the top of Fish mountain; near Lake Pleasant
village; and three-fourths of a mile east-southeast of Lookout
mountain are mostly of hornblende gneiss, usually garnetiferous.

A fine exposure of Grenville limestone is shown in the old quarry
144 miles east-southeast of Lake Pleasant village. The rock is a
medium-grained, greenish-gray, calcitic marble, its greenish color
being due to the presence of many tiny, well-serpentinized crystals
of pyroxene. Occasionally large blotches or patches of deeper
green serpentinized material occur, causing the rock to have a sort
of “verde antique’ appearance very. similar to that of the marble
recently described by the writer from the quarries near Thurman
in the North Creek quadrangle.

GEOLOGY OF LAKE PLEASANT QUADRANGLE 13

In the Grenville mass, which is really a distinct inclusion in the
syenite, just south of Elbow mounéain, the well-bedded rocks are
chiefly hornblende-feldspar-garnet gneisses together with a little
quartzite, white feldspar gneiss and a one-foot bed of white lime-
stone, this last lying within the hornblende gneiss. There is rather
clear evidence for the fusion, and at least partial assimilation, of
the borders of this inclusion giving rise to massive rocks of inter-
mediate appearance and dioritic composition. These intermediate
rocks at times look like basic syenites.

Just southeast of the summit of Dunham mountain two small
inclusions of biotite-garnet gneisses are shown on the map. These
are more or less assimilated by the syenite and are representative
of a number of smaller inclusions in this vicinity.

The large inclusion extending across the top of West Hill is a
nearly black hornblende-feldspar-garnet gneiss or amphibolite with
garnets only occasionally present. Three smaller inclusions lie south
-and southeast of this and consist of white, feldspar-quartz-biotite-
garnet gneisses distinctly interbedded. All four of these inclusions
are very clear-cut with good exposures in open fields.

A small inclusion one-half of a mile south of the mouth of
Colombe brook shows a sharp contact with syenite along the road.
The rocks are well banded, light to dark gray, feldspar to biotite
gneisses usually with garnets.

Anorthosite-gabbro

In the extreme northeastern corner of the quadrangle, an area
of about I square mile is mapped as anorthosite-gabbro. Beyond
the map limits the extent of this rock has not been determined,
though the nearest ledges to the south and west show syenite of
rather normal character. It is admittedly possible that this so-called
anorthosite-gabbro mass is only a very basic phase of the syenite,
though in one or two essentials it is different from any such rocks
below described. In mineralogical composition and outward ap-
pearance, however, it is decidedly like the characteristic anorthosite
or anorthosite-gabbro of the great Essex county area, and hence
it is rather confidently classed with that rock. In thin-section the
typical rock shows: 88 per cent oligoclase to labradorite, mostly the
latter ; 3 per cent augite; 2 per cent each of hypersthene and horn-
blende; 1% per cent garnet; I per cent each of biotite, magnetite
(or ilmenite), and quartz; and a little zoisite and apatite. The
quartz is probably of secondary origin. Thus the minerals other

I4 NEW YORK STATE MUSEUM

than feldspar rise to 12 per cent, and the rock should be classed
with the anorthosite-gabbro phase of the great anorthosite area.

The rock is light gray, moderately gneissoid, and usually highly
granulated except for occasional large (1 inch), dark blue labrador-
ite crystals which remain as ungranulated cores. As Cushing
states,’ the lighter colored granulated feldspar has plainly originated
from the crushing of the large dark blue feldspars.

This mass of anorthosite is farther separated from the great area
in Essex and Franklin counties than any other so far discovered,
the small area at Rand Hill in Clinton county being the next most
distant. According to Cushing? the anorthosite is younger than,
and intrusive into, the Grenville but older than the syenite.

Syenite

An exceedingly variable series of rocks is comprised under the
term syenite as here considered. From a normal or typical mod-
erately quartzose syenite, the variation is to a granitic syenite on one
hand and through to almost gabbro on the other. For the sake of
convenience the normal syenite will be discussed first and then the
basic and acidic phases, though it must be clearly understood that
these variations of the syenite mass are in no sense sharply separable.

Normal syenite. What is regarded as normal syenite occupies
fully one-third of the area of the quadrangle or about 75 square
miles. It is the most extensive rock of the region. It is almost _
invariably moderately quartzose, the average amount of quartz
being 10 to 15 per cent. When the quartz content runs higher than
20 per cent the rock is no longer regarded as normal syenite. More
or less plagioclase (5 to 25 per cent), generally oligoclase to andesine,
is also always present. When quartz is absent and the lime-bearing
feldspars exceed the alkali feldspars, the rock is classed with the
basic phases of the great syenite mass. Microperthite is rarely
absent and ranges in amount from 10 to 16 per cent. From Io to
25 per cent of orthoclase generally occurs. From 8 to 20 per cent
of pale green augite with good cleavage occurs in two-thirds of the
slides examined. Hypersthene was noted in but one slide. Horn-
blende (deep green to yellowish green) is almost always present in
amounts up to 15 per cent. Small percentages of magnetite, zoisite,
and zircon never fail. Small amounts of garnet and apatite occa-
sionally appear. One slide shows a few grains of epidote. These

1N. Y. State Mus. Bul. 95, p. 305.
2N. Y. State Mus. Bul. 115, p. 480-81.

GEOLOGY OF LAKE PLEASANT QUADRANGLE 15

mineralogical variations of the normal syenite are clearly brought
out in the table on page 16.

The color, textural, and structural variations are scarcely less
notable. Where fresh, the normal syenite shows the dark greenish-
gray color so common throughout the Adirondacks, and the -
weathered surface, from a fraction of an inch to 2 or 3 inches
thick, shows a light brown color. Ledges in the woods often are
light gray on the immediate surface, probably due to the action of
decomposing organic matter upon the iron compounds. Such light
gray to almost white surfaces are particularly well exhibited on the
top of Cathead mountain recently burned over.

The normal syenite is typically medium grained though at times
it varies to fine grained, while again it becomes moderately coarse
grained to even porphyritic. Granulation is nearly always shown,
sometimes to a high degree especially as regards the quartz and
feldspar.

The rock is always more or less foliated. In some ledges the
gneissic structure is so faintly developed as to be made out with
difficulty if at all. In other places the foliated structure is so
thoroughly developed that the rock presents an almost schistose
appearance. Such a high degree of foliation is frequently asso-
ciated with and parallel to shear zones along which biotite has
developed at the expense of pyroxene or hornblende. Such rocks
often split readily into thin layers. Among other good examples
is the ledge in Elbow creek at the mouth of the gorge a mile north
of Wells. The finer grained syenites are mostly associated with
such shearing which has produced excessive granulation. Most
commonly the gneissic structure is so developed as to give the rock
a distinctly streaked but not banded appearance due to a drawing
out of the dark minerals into crude parallelism.

That the syenite is younger than the Grenville is proved by the
presence of distinct Grenville gneiss inclusions such as near the
summit of Fish mountain; just southwest of the summit of Mount
Dunham; along Elbow creek between Elbow mountain and Mount
Rouge; one-half of a mile south of the mouth of Colombe brook;
just north of Jacksons seat; and at many other places. The normal
syenite, however, is apparently freer from inclusions than its more
basic or acidic phases or than the granite. In certain of the mixed
gneiss areas the syenite is seen to have literally cut to pieces the
Grenville.

NEW YORK STATE MUSEUM

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Solovy S}I puv ojtuaAs jo sojdwexq

GEOLOGY OF LAKE PLEASANT QUADRANGLE i?

Basic phases of the syenite. As above stated, the normal syenite

in one direction grades into rocks of basic (dioritic or even gabbroic)
composition. Only five areas of such rocks are of sufficient size
‘to be represented upon the geologic map, and altogether these are
only about 8 square miles in extent. There are, however, in other
portions of the quadrangle, especially in the mixed gneiss areas,
some small rock masses of the same general character that have
quite certainly been produced by magmatic assimilation of Grenville
by granite or syenite.

Mineralogically the basic syenite differs from the normal syenite
chiefly in its usual absence of quartz, microperthite, and orthoclase ;
predominance of plagioclase (often basic) ; and the frequent -pres-
ence of scattering, small to large clear-red garnets. Many times
rocks of transitional character occur like those represented by slides
number 9 and 15 in the table on page 16 and at various places in
the field. Often, as on the eastern face of Speculator mountain and
on the mountain side a mile southeast of Sand lake, these basic
rocks have a decided gabbroic appearance so that in certain cases
the distinction between these and the latter gabbros can not always
be made with certainty, as will be pointed out in the discussion of
these later gabbros.

As regards color, texture, and structural features, the same sorts
of variations described in connection with the normal syenite apply
here.

Some years ago, in the Diana-Pitcairn area of the western Adiron-
dacks, Smyth? proved that the prevailing normal augite syenite at.
times shows a perfect transition to a distinctly more basic gabbroic
rock. Judging from his description, the phenomena there are much
like those here considered.

Within the Long Lake quadrangle Cushing? has found a basic
phase of the normal syenite, but it always lies along the border
between syenite and anorthosite and hence strongly suggests the
incorporation of some of the anorthosite into the molten syenite to
produce the basic phase.

Recently the writer has proved ? that, on Gore mountain in War-
ren county, a long narrow zone of basic syenite has been produced
by melting and assimilation of the border of a large inclusion of

1 Geol. Soc. Am. Bul. 6, 1895, p. 271. 17th Annual Rep’t N. Y. State Geol.,
1897, Pp. 472-74.

2N. Y. State Mus. Bul. 115, p. 479.

3 Econ. Geol., vol. 7, no. 5, 1912, p. 498-501. Also N. Y. State Mus. Bul.
164, p. 100-2.

18 NEW YORK STATE MUSEUM

dark, basic Grenville gneiss by the syenite magma and also that a
much larger mass of basic syenite at the Hooper mine near
Thirteenth lake in Warren county is almost certainly due to mag-
matic assimilation of basic gneiss. Specimens from these two
localities show almost exactly the same characteristics as the typical
basic syenites from the Lake Pleasant quadrangle.

The Speculator-Lookout mountain area of so-called basic syenite
is the largest within the Lake Pleasant quadrangle. -Numbers 12,
13 and 17 of the table on page 16 represent the most basic and
least syenitic facies of the area. While all the rocks are distinctly
basic, nevertheless considerable variations in mineral content occur.
Thus near the west end of the area the rock is rather coarse grained
and gabbroic-looking, sometimes with many garnets and sometimes
without them. In the creek just east of Sand lake, the rock looks
much like certain garnet-bearing, border phases of anorthosite
described by both Cushing and Kemp. The garnets do not appear
to be of secondary origin. On the mountain a mile southeast of
Sand lake, the garnets disappear and the rock passes over into
a good hornblende syenite. The Speculator mountain mass looks
rather syenitic with garnets in the rock along Sucker brook and
considerable biotite and few garnets at the mountain summit.

There is considerable evidence that this Speculator-Lookout
mountain mass has been produced by magmatic assimilation where
dark, hornblende-feldspar-garnet Grenville gneisses were incor-
porated into the normal syenite magma. This suggestion is borne
out by the actual presence of a considerable inclusion (see map) of
such rock one-half of a mile southeast of the southern end of Lake
Pleasant. In thin-section this inclusion contains the following
mineral percentages: hornblende 40; oligoclase to labradorite 30;
hypersthene 18; garnet 10; and magnetite and pyrite 2. The borders
of the inclusion appear to have been well fused by the enveloping
magma and in places this assimilation product greatly resembles
the typical basic phase of syenite just to the west. This inclusion
doubtless represents one of the last fragments of dark gneiss to have
been engulfed by the syenite magma when the temperature had
become too low for complete melting and assimilation of the frag-
ment. If many such masses of dark gneiss were actually enveloped
by the normal syenite magma and fully assimilated, the origin of
this large area of basic syenite finds a ready explanation. That
this magma did break through and rather thoroughly assimilate con-
siderable quantities of such basic Grenville rocks are strongly sug-

GEOLOGY OF LAKE PLEASANT QUADRANGLE I9

gested by the above-mentioned partially assimilated inclusion; the
fact of the former presence of much Grenville hornblende gneiss
associated with more or less limestone in this northern portion of
the quadrangle as proved by the inclusions and the large area just
west of Speculator village; the variable composition and appearance
of the so-called basic syenite which would be expected because of
the differences in amount and character of the rocks assimilated;
the gradation of the basic syenite into the normal syenite; and
the fact that these basic phases of the syenite so greatly resemble
similar rocks definitely known to have been formed by such a
process of magmatic assimilation in Warren county (see above).
The second largest basic syenite area extends from Finch moun-
tain to near the mouth of Ninemile creek. Toward the west the
rock is much like the typical basic syenite from the Speculator-
Lookout mountain area just described. In a big ledge along the
river 144 miles below the mouth of Ninemile creek, the rock is
light brown, moderately coarse grained, very gneissoid, and rich in
feldspar, with scattering hornblende crystals and occasional small to
large red garnets (see no. 3 of table on page 16). This rock is
distinctly different in appearance and composition from the normal
syenite, while it is in every way very similar to one of the transi-
tional phases between basic Grenville and normal syenite in the
Rogers mine in Warren county.’ The clew to the origin of the
rock 1% miles below the mouth of Ninemile creek appears to be
furnished by another ledge along the river one-third of a mile below
the mouth of the same creek, where part of the ledge, consisting of
good syenite without garnets and only moderately gneissoid, grades
rather rapidly into the very basic and gneissoid garnet-bearing rock.
It seems clear that this latter rock has been produced by nearly
complete assimilation of a very basic older rock still visible. One-
half of a mile below this ledge on the river, a mass of rather finer
grained syenitic rock is streaked with Grenville dark gneiss inclu-
sions or stringers where the assimilation has not been complete.
Farther eastward, as in Finch mountain and also in the area lying
directly across the river from this mountain, the rock is rather fine
grained, more highly granulated, very gneissoid to schistose, more
biotitic, with hypersthene instead of hornblende, and without gar-
nets (see no. 9 of table on page 16). It appears to be a more highly
foliated or often sheared phase of the basic syenite with greatest
development of biotite along the narrow shear zones. The Finch

IN. Y. State Mus. Bul. 164, p. 101-2.

20 NEW YORK STATE MUSEUM

mountain basic syenite was doubtless continuous with that across
the river before the gabbro intrusion.

The area of basic syenite in the vicinity of The Gorge can not be
very satisfactorily delimited, but it appears to occupy less than I
square mile as shown on the map. Good exposures occur along the
river where the rock is greenish gray when fresh, medium grained,
distinctly gneissoid and granulated, and consists chiefly of plagio-
clase and diallage (see nos. 11 and 53 of table on page 16). In
The Gorge this basic syenite does not seem to be sharply separated
from the gabbro (see below), and its relation to the other rocks,
except the diabase, is not apparent.

In the small basic syenite area near Fiddler’s lake, the rock has
a mineralogical composition (see no. 14 of table on page 16) very
similar to that of the Speculator-Lookout mountain area, while
megascopically it is practically indistinguishable from the typical
augite syenites represented by numbers 5, 6, and 10 of the table.

A good example of the small masses (not mapped) of what look
like basic phases of the syenite is the single big ledge in the bed
of the river within the mixed gneiss area one-half of a mile south
of Meco lake. Its composition is rather gabbroic and considerable
quartz content is noteworthy. The field relations clearly indicate
that this rock originated as an assimilation product. _

Number 15 of the table on page 16 represents another such rock
intermediate in character between the most basic and the normal
phases of the syenite. This rock, taken from the eastern border
of the small Grenville area or inclusion south of Elbow mountain,
has quite certainly been produced by the assimilation of some of the
basic Grenville by the syenite magma. At several places the various
stages in the process of assimilation of the borders of the Grenville
inclusion (see map) are represented by rocks of peculiar appear-
ance.

_ Still another example certainly due to assimilation is represented
by number 24 of the table and described later in connection with the
granitic syenite.

Granitic syenite. Under this heading are included all those rocks
which are transitional in character between the normal syenite and
the granite. Because of their intermediate features, accurate de-
limitation of these rocks, from the normal syenite on one side and
the granite on the other, is often not possible in the field. Suff-
ciently detailed work has, however, been done to warrant a roughly

GEOLOGY OF LAKE PLEASANT QUADRANGLE 2I

separate representation of these transitional rocks upon the geologic
map. Within these areas there are occasionally narrow bands or
masses of normal syenite or granite approximately parallel to the
foliation, but no attempt has been made to show them upon the
map. As nearly as can be judged, this granitic syenite occupies
between 35 and 4o square miles of the area of the quadrangle.

Mineralogically, the higher quartz content; frequent presence of
microcline; invariable presence of biotite; and general absence of
pyroxene characterize the granitic syenite as opposed to the normal
syenite. When the quartz content runs higher than 25 per cent,
the rock is classed with the granite.

The rock shows practically the same textural and structural fea-
tures as those of the normal syenite.

In addition to color variations like those of the normal syenite,
the granitic syenite often has a pinkish-gray to reddish color which
apparently is not always confined to the mere weathered surface.
Regarding the granitic syenite of the Long Lake quadrangle, Pro-
fessor Cushing says:1 ‘“‘ Much of the rock is alternately green and
red, quite quartzose, and a rock distinctly intermediate between
syenite and granite, often passing into granite. Much of it is uni-
formly red, and the red rock ranges from syenite to granite in com-
position.” These statements apply equally well to the region here
under consideration.

A single rock ledge, 1 mile due southeast of the summit of
Hamilton mountain, furnishes interesting evidence regarding the
intimate relationships of dioritic, granitic, syenitic, and Grenville
gneisses. All these rock types are clearly exhibited in this ledge
about 40 feet across and their compositions, except the Grenville, are
shown in the accompanying table:

oO
Le us 2
Ss Ss 5
leer | : 2 2
g 3 a, ° a a4 = % 7 2
Pes he Qa Net Be S iahe 3 ea ba ae ae
Og, Pt a a a A 5 ie (ed al tee Bell pe
— La —_ col ort oi:
a fo) = re a ea ae ae Pe S nS &
24 Nal Pear 55 I3 7 Bi Ntecei ore oes I Littles Pesce
23 Ad | 23 22 BW steers 5 I} 3 ttle; eae as
21 25 38 5 27 Uns stata emaisiens I 4 little

No. 24 is a rather basic (dioritic) rock greatly resembling certain
phases of the basic syenite; no. 23 is a granitic syenite; and no.

IN. Y. State Mus. Bul. 115, p. 478.

22 NEW YORK STATE MUSEUM

21 is a good pink granite. These types grade back and forth into
each other several times in this one outcrop. There are many
narrow streaks, layers, or inclusions of Grenville dark, biotite-
feldspar-quartz gneiss sometimes containing garnets. At times
these streaks are rather clearly defined, while again they are not,
but always, though often locally twisted, they roughly follow the
gneissic bands. The texture and homogeneity, especially of the
granite, vary considerably and a few garnets occur sporadically in
the syenitic and granitic facies. The ledge is perfectly bare with
relationships well shown, and it seems certain that the dark (dioritic)
streaks are Grenville which have been more or less fused into the
molten granite. Where thoroughly assimilated, the basic rocks have
resulted, and where not thoroughly fused in the streaks are still
visible. Every stage of the assimilation process is shown.

Another locality where the relationships between syenite, granitic
syenite, and Grenville are very clearly exhibited on a much larger
scale is in the vicinity of the top of Mount Francisco. Begin-
ning one-quarter of a mile northeast of the mountain top and pass-
ing one-half of a mile southwestward across the mountain top, one
may observe the gradation from basic syenite, through normal and
granitic syenite to pinkish granite. The mountain top has been
burned over, thus exposing a great bare rock ledge in which the
normal syenite (no. 27 of table on page 16) grades perfectly into
granitic syenite (no. 27b of the table), and this into typical granite
(no. 34a of the table on page 26).. There is no possibility that one of
these rocks cuts another. The basic syenite (no. i2 of table on page
16) also almost certainly grades into the normal syenite. From the
basic syenite to the granite there is a progressive diminution of the
dark-colored minerals from 19 to 3% per cent. From the normal
syenite to the granite no streaks or inclusions of Grenville were
noted so we here seem to be dealing with a case of simple differ-
entiation.

At many other places, especially within the large granitic syenite
area between Whitehouse and Hamilton mountain, there are more
or less intimate relations of syenite, granitic syenite, and granite.
Thus just east of Buck pond the granitic syenite contains a layer
(several feet wide) of pink granite and it is not a dike. From
this point southwestward for one-half of a mile, there are shown
by rapid gradations all sorts of rocks from hornblende syenite and
granite to almost granite porphyry. Such rocks play back and
forth upon each other repeatedly.

GEOLOGY OF LAKE PLEASANT QUADRANGLE 23

On the prominent mountain spur 2 miles east of Whitehouse, the
rock toward the base is mostly normal syenite which, about half
way up the mountain, gives way to a prevailing granitic syenite,
but with all types from hornblende syenite to pink granite or granite
porphyry grading into each other rapidly. |

Along the creek from one-half to 114 miles north of Whitehouse,
there are good ledges of syenite to granitic syenite, chiefly the latter,
which are often pink and variable in appearance because of occa-
sional dark gneiss streaks or bands. This rock strongly suggests a
transition one from ordinary granitic syenite to the pink granite
with its amphibolite bands below described as occurring on Hamil-
ton lake stream.

These detailed descriptions are here given to show that, so far
as the writer’s observations are concerned, there is no evidence for
different ages of normal syenite, granitic syenite, and pink granite,
but rather there is much evidence that these types grade into each
other and are really only different phases of the same great plutonic
body. In no case has one of these rocks been found definitely to
cut another, though rapid variations and gradations are frequent
and many times these closely involved rocks are intimately associated
with streaks of Grenville gneiss. Such Grenville shows all stages
of having been more or less assimilated or incorporated by fusion
into the igneous masses.

Thus it is difficult to resist the suggestion that some at least of
these acidic variations of the normal syenite are to be accounted for
on the basis of magmatic assimilation where acidic Grenville has
changed the composition of the syenite magma. This view does
not, however, preclude the possibility of considering other acidic
variations from the normal syenite as due to a process of pure
differentiation as is probably true of the Mount Francisco mass
above described. The writer inclines to the belief that such pure
differentiation has been the principal factor in the production of
the large masses of granitic syenite and granite. Still again, the
more or less perfect assimilation of Grenville gneiss fragments by
the granitic portion of the magma has quite certainly caused many
of the puzzling, rapid, local variations of the rock by the formation
of masses of intermediate character.

Granite
Approximately 35 square miles of the area of the quadrangle are
occupied by granite. This is a reddish to grayish granite gneiss _
which, for most part at least, is quite certainly only the extreme

24 NEW YORK STATE MUSEUM

acidic variation of the normal syenite. Examples of such variations
are given above in the discussion of the granitic syenite. Also, in
another direction, there is a transition to the granite porphyry be-
low described.

Texturally and structurally the granites show practically the same
variations as the normal syenite and no restatement of these is here
necessary. The pinkish-gray color is usually not a mere surface
weathering effect, but pervades the whole rock body and appears ‘to
be due to stains and specks of hematite. In the table on page 26
the mineralogical compositions of selected examples are given.
Compared with the normal syenite there are to be noted especially
the frequent occurrence of considerable microcline; higher quartz
content; the lesser prominence of hornblende; and the greater
prominence of biotite.

Included streaks or bands of Grenville or amphibolite are more
common in this pink granite than in any of the other rocks, though
these by no means always occur. Some considerable areas of rather
homogeneous granite are practically free from inclusions. For
example, almost continuous ledges of very typical reddish, biotite
granite gneiss, along the creek from I to 2 miles east of Alvord
P. O., are almost wholly devoid of inclusions.

Along the creek from one-fourth to one-half of a mile below
Dunning pond, there are big ledges of variable granitic syenite to
red granite so full of gray Grenville gneiss inclusions as to make
up a considerable percentage of the rock. Usually these inclusions
are drawn out parallel to the foliation, though sometimes they are
twisted into various positions and frequently they pinch out sud-
denly. There appear to be all stages from thoroughly fused in
Grenville to some which has been but little affected. At one place
syenitic-looking rock was seen in the same ledge with granite and
the syenite seems to have been produced by assimilation of Gren-
ville by the syenite magma.

A very fine display of the red to gray granite with numerous in-
clusions may be seen in the big ledges in the bed of Hamilton Lake
stream one-half of a mile below the mouth of Gallup creek. Much
of this rock is distinctly banded due to alternating layers (up to
3 feet wide) of reddish granite and amphibolite, the latter being
inclusions drawn out parallel to the very distinct foliation of the
granite. At times the whole shows a considerable twisted or con-
torted structure. These ledges look more like the so-called
“Laurentian” granite of the Thousand Islands region than any
others seen within the quadrangle.

GEOLOGY OF LAKE PLEASANT QUADRANGLE 25

For 2 miles up Ninemile creek from its mouth, there are many
outcrops of pink to red granite but all the rock is massive and
homogeneous, though very gneissoid, except at one locality, namely,
one-quarter of a mile above the gabbro stock or dike where am-
phibolite inclusions cause the rock to appear much like that just
described as occurring on Hamilton Lake stream.

The vicinity of West hill, southeast of Wells, should be men-
tioned as another good place for the study of the pink granite
with inclusions because of numerous exposures in open fields.
This granite is not always homogeneous, but shows variations .
occasionally to granitic syenite or even to normal syenite. There
are many inclusions, three being of sufficient size for separate map-
ping as Grenville. The largest inclusion is of hornblende gneiss
much like that so often associated with Grenville limestone, while
the two smaller inclusions are of Grenville white acidic gneiss.
Many ledges show streaks, bands, or thin lenses of gray or white
gneisses exhibiting all stages of assimilation by the granite.

Granite and syenite porphyries

These rocks are practically identical in composition and appear-
ance with the granite porphyries recently described by the writer}
as occurring in the Broadalbin and North Creek quadrangles. On
the accompanying map six areas of these rocks are shown, these
being confined to the northern and eastern portions of the quad-
rangle and comprising some I2 or 13 square miles of its area.

In the table on page 26 the mineralogical compositions of several
carefully selected examples are given. A comparison with the
granite shows essentially the same mineral variations and constants
except that at times the quartz content is so low that the rocks are
more properly syenite porphyries. Such less quartzose porphyries
are of minor extent.

The porphyritic texture is generally pronounced with phenocrysts
of potash feldspar up to an inch long standing out clearly, though
usually these phenocrysts are rather well granulated. The degree
of foliation varies widely from moderate to such an extreme that
the quartz and feldspar crystals are well flattened out.

As seen on the weathered surface, the color is nearly always
pinkish to reddish gray, and generally this color seems to pervade
the whole rock, though in the bed of Devorse creek a ledge of very
fresh granite shows a greenish gray color.

1N. Y. State Mus. Bul. 153, p. 17-20. N. Y. State Mus. Bul. 170,
p. 21, 22.

26 NEW YORK STATE MUSEUM

The rocks are certainly only porphyritic phases of the granite or
syenite. Thus the only considerable mass of syenite porphyry is
that of Groff mountain which, toward the west, becomes more
quartzose and less porphyritic and grades through granitic syenite
into granite, while toward the south it merely loses its porphyritic
texture and passes into normal syenite. Whitman mountain con-
sists of typical granite porphyry which grades southward, especially
along Devorse creek, into granite and northward into the granite
of the West hill area. From 1 to 2 miles northeast of Elbow
“mountain, the small mass of granite porphyry shows a perfect
transition westward into pink granite. Similar gradations have been
observed in other porphyry areas. |

Some of the best exposures of typical granite porphyry occur
along Dewey creek, Devorse creek, the Sacandaga river in the gorge
just below Auger flats, and on the hill just east of Echo lake.

Examples of granite and granite and syenite porphyries

| g aul |
Lo ocala en eee Z 4 Nive
g | g 3 a | 3 3) N -E | 3 ®
; | s|s| 8 ° $/8/8 a8] gs BA Slee
I ee: a ee Bp a) ele. a Ss fe | eee
= UR ie ae Pea & sae ee ae eee ee 5 as) 3 a,
na ro | Oth ee has AY | ot |) a1 a N N < <
Rerenrs Ceca Sires eee haces: are e! saaboh Bisa cole
|
2 | 28 Skr | 25 | 20)....| OlAn.5 301} 5 572s FO 2 ape ee. ee
=. 30 ROGE | oF) 301 BS, ca cue Lee a6 bs, his 3 little | little |....| eww aoe
= | 33 734 || 304 3501 30 Ol.-An. 7 BO e+ na] Go) Ty Bittle |) xe alc oe ane
& | 32] 1313 | 20} 15] 5 | Ol-An.1o | 35) 5|8 | 1 [little | 43 /....} little
34 BADE MES Wl agoicce st Ol. 2 50 6 4/1 little || Tittle: + «25:0 atom ieee
» | 34a 14d4 | Io | 30 |. Ol. 26 30 Ona % | little | little |....| little
el | |
5 | 35 sl2_ | 5 | 30] 15] Ol-An.15 | 15 Zl ig | 2 3 £1. ea eo
“a | 36 5m7 35 |..-.| | OL-An. 25 | 28 Awe. wil 33 + | es eee
S | 37 Siro Wi Sait (Se Ol.-An. 35 | 20 Sa ce 4 | NS al ees
Ay | 38 1712. | 18 | io.) 25) IOl-An.- 75 -| 40 9/3 |2 3 OY «ove ot iw wie
: |

Mixed gneisses

Six areas of mixed gneisses are shown on the geologic map.
Grenville gneisses are more or less prominently represented in all
these areas but they are so thoroughly cut up by, and involved with,
the great intrusives as to preclude the possibility of separately
mapping them. In many places outside these mixed gneiss areas
there are locally developed rocks of somewhat mixed gneiss appear-
ance, but in all such cases either the intrusive or the Grenville
very distinctly predominates. Many times there occur rocks of
intermediate character between the Grenville and the granites or
syenites and there is no escape from the conclusion that many at
least of such intermediate-looking rocks have been produced by
magmatic assimilation. Admittedly, however, there are within these

GEOLOGY OF LAKE PLEASANT QUADRANGLE 27

areas certain peculiar rocks whose origins have not been demon-
strated. |

The mixed gneiss area between West hill and Mount Dunham
shows, in its northern part, Grenville hornblendic, quartzitic, and
biotitic gneisses intimately associated with syenite to granitic syenite,
the latter being literally all shot through the Grenville, giving rise
to typical mixed gneisses with numerous streaks, inclusions, and
bands of Grenville. In its southern part this igneous rock is
variable gray to pinkish granite with Grenville gneisses more or
less thoroughly fused in.

Very similar phenomena characterize the larger mixed gneiss area
which extends eastward from the confluence of the two branches of
the Sacandaga river. Dark-gray, hornblende-garnet or biotitic
gneisses are all cut to pieces and often considerably fused by
granitic syenite and pink granite. There are excellent exposures
along the river one-quarter of a mile above and one-half of a mile
below the mouth of West Branch Sacandaga river, and also above
the road east of Colombe brook.

In the Little Cathead mountain mixed gneiss area, which is the
largest of the quadrangle, Grenville gneisses are all cut to pieces
by gray granitic to syenitic gneisses, but in general there is com-
paratively little evidence for assimilation. The Grenville gneisses
of the whole area, except the northern portion toward Cathead
mountain, are well banded and rich in quartz, feldspar, biotite, and
garnet. Toward Cathead mountain the Grenville appears to be
mostly either quartzite or gray to white feldspar gneiss. Excellent
outcrops occur one-half of a mile north-northeast of Benson Center ;
on the east face of Little Cathead mountain; on Cathead mountain ;
and above the road about a mile northeast of Benson P. O.

A poorly defined area just north of Moose mountain shows much
Grenville garnet-bearing quartzitic gneiss frequently cut through
by granitic syenite.

In the small area south of Meco lake mostly light gray Grenville
gneisses are verly closely involved or fused together with syenitic
to granitic gneisses. Almost continuous ledges occur in the river
bed. One big outcrop looks like basic syenite which in thin-section .
is shown to be a quartz diorite, and this rock is fairly certainly an
assimilation product.

The small area in the extreme southwestern corner of the map
shows few exposures, but the rocks appear to be mostly dark-gray
Grenville gneisses and pink granite to granite porphyry intimately
associated.

28 { NEW YORK STATE MUSEUM

Gabbro

Five gabbro areas are indicated on the geologic map. These
rocks are all considered to belong to the later Precambric (Post-
syenite) series of gabbros now well known throughout the Adiron-
dacks. Within the quadrangle, as usual elsewhere, these rocks show
decided variations, especially textural and structural, and this, to-
gether with the lack of definite relationships with the surrounding
rocks in certain of the areas, causes some uncertainty in regarding
them all as of the same age. All these rocks, however, are true
gabbros with certain general characteristics (for example, com-
position) in common, and they are even less variable than the finely
exhibited gabbros of the North Creek quadrangle recently discussed
by the writer.’

In appearance some, and in composition all, of these gabbros
most nearly resemble the basic phases of the syenite. The greater
proportion (about 40 per cent) of dark-colored minerals with
hypersthene usually prominent; nearly constant presence of am-
phibolite facies; and the occasional diabasic texture are rather
characteristic of the gabbros as against the basic phases of the
syenite.

The most typical gabbro occurs in the dike a mile east of the
south end of Wells village. This dike shows a width of about
40 feet and a length of about 300 feet, with nearly east-west
strike parallel to the foliation of the country rock. The main body
(interior) of the dike is medium grained, devoid of foliation, and
has a good diabasic texture. On the borders there is some very
gneissoid amphibolite. Several small pegmatite dikes cut the gabbro.
~The country rock is quartz-hornblende syenite with which the
gabbro is in sharp contact at one place. ‘Toward the east end an
inclusion of very gneissoid syenite appears to be without sharp
contacts against the gabbro, its borders having been fused and
mixed with the gabbro. No. 52 of the table on page 31 shows the
composition of this rock, the presence of so much hornblende to
the exclusion of hypersthene being exceptional for the quadrangle.
Possibly this is because original pyroxene has all been altered to
hornblende. The feldspar is mostly labradorite.

Near Alvord P. O., there occurs a small mass of gabbro as a
single large exposure not in actual contact with the country rock
which here is granite porphyry, but there can be little doubt as to
its later intrusive character. It is moderately gneissoid and, though

1Jour. Geol., vol. 21, no. 2, 1913, p. 160-80. Also N. Y. State Mus. Bul.
170, p. 26-35.

GEOLOGY OF LAKE PLEASANT QUADRANGLE 29

lacking a diabasic texture, it is almost exactly like the most typical
gabbro of the North Creek quadrangle in composition (see no. 51
of table on page 31). The feldspar is largely labradorite.

The gabbro mass at The Gorge is of particular interest. It ap-
pears to be of the nature of a stock rather than a dike, though
the excellent exposures are almost wholly confined to the river
channel. From the interior of the stock near the mouth of The
Gorge, very fresh, moderately gneissoid, medium-grained, dark
greenish-gray rock may be obtained. This rock never shows a
diabasic texture but it does exhibit that peculiar mottled appear-
ance so often seen in the Adirondack gabbros. This mottled appear-
ance is due to the irregular distribution of the black hypersthene
crystals through the greenish-gray mass of granulated feldspar.
No. 49 of the table on page 31 shows the composition. Near the
mouth of The Gorge a twenty-foot wide band of amphibolite was
noted, and one-quarter of a mile below this a forty-foot wide mass
of pink granitic syenite extends across the river with gabbro in
close proximity on either side. This pink rock is either a large in-
clusion or tongue of country rock (see map) through which the
gabbro has broken as proved by the existence of two much smaller,
though very distinct, masses of the same pink rock as inclusions
in the gabbro. Near its eastern end several small inclusions (a
few feet across) of a light brown, basic phase of the syenite may
be seen sometimes with sharp boundaries and sometimes showing
rapid gradations into the gabbro due to partial melting. In spite
of nearly continuous exposures along the river, the western border
of the stock is not clearly defined. There is quite certainly a
fairly rapid gradation of the gabbro into the basic syenite apparently
due to local assimilation by the molten gabbro.

Just above the mouth of Ninemile creek there are some big
ledges of gabbro, these being the only exposures in the area here
shown on the map. In texture, structure and composition (see
no. 47 of table on page 31) this rock is very similar to that in
The Gorge. On the south side this gabbro is seen to be much
finer grained and excessively gneissoid but without change in com-
position (for example, no. 50 of the table). This finer-grained
mass is only an amphibolite phase of the gabbro. The country
rock is pink granite, and the gabbro contains some inclusions of this
granite in the form of streaks or bands from 2 inches to I foot
wide, parallel to the foliation, and often pinching out abruptly.

The 2 mile long area mapped as gabbro in the valley of the
West Branch of the Sacandaga just above Blackbridge presents

30 NEW YORK STATE MUSEUM

some rather puzzling features. Its relation to the surrounding rock
is not so well known, but the best evidence points to its classification
with the other gabbros. Admittedly, however, some of the rock
of this area may belong with the so-called basic syenite. For most
part it is a very basic, gabbroic-looking rock, sometimes rather
massive and coarse grained with feldspar and hornblende or hypers-.
thene individuals up to an inch long, and at other times not so
coarse but streaked or almost banded, due to layers of amphibolite.
All phases of the rock are much granulated and distinctly gneissoid,
the coarser grained portions being least so. In spite of these
strongly developed secondary features, a coarse diabasic texture is
still frequently noticeable. Number 48 of the table shows the
composition of the typical medium-grained rock. Labradorite is
the most abundant feldspar, while garnet is common and probably
secondary. The most probable explanation of these features seems
to be that a large mass of coarse-grained gabbro was here in-
truded and that, under excessive subsequent pressure, varying
degrees of foliation and granulation have been produced.

| Diabase

Six diabase dikes have been located within the quadrangle, and
these are very similar to others so well known throughout the
Adirondack region. They are of late Precambric age and wholly |
nonmetamorphosed. All but one of the dikes strike nearly north-
east-southwest, which is quite the rule for northern New York.
With one exception, these otherwise fine-grained rocks are more
or less porphyritic, due to the presence of phenocrysts of fresh
labradorite feldspar up to an inch in length. A diabasic texture
occurs in all but one dike, and such texture is sometimes very per-
fectly developed. In the table on page 31 the mineralogical com-
position of a sample from each dike is shown. The augite is the
common pale reddish-brown variety with good cleavage, and the
hornblende is the common green pleochroic variety, the chlorite
having been derived from either of these.

The diabase 1% miles northeast of Guideboard hill (no. 44 of
table) is of interest because it shows at once porphyritic and
diabasic textures and some glassy ground mass. Its weathered
surface has a distinct pitted appearance due to more rapid dis-
solving out of the feldspar phenocrysts.

1Since this was written the writer has discovered a rock of almost ex-
actly the same sort within the Blue Mountain quadrangle and which is
there very clearly only a metamorphosed portion of a gabbro stock.

GEOLOGY OF LAKE PLEASANT QUADRANGLE 3!

In the bed of West Sacandaga river just above The Gorge,
a dike, 4 feet wide and traceable 50 feet, lies in the ten-foot wide
crushed zone of a fault. It is all coarsely brecciated except a
narrow tongue which extends Io feet into the country rock. While
we can not be positive that this molten rock was intruded along a
fault, we are at least certain that movement along a fault here
took place after the intrusion. This is the only one of the dike
rocks (no. 41 of table) which fails to have a porphyritic texture.

Two small dikes (nos. 40 and 46 of table) from 10 to 25 feet
- wide and 50 to 60 feet long occur along a fault in the bed of Nine-
mile creek. In the more southerly one (no. 40 of table) the rock
is much broken as a result of fault movement. The more northern
one shows contact with pink granite. Both dikes have porphyritic
and diabasic textures.

On the road, one-half of a mile below the mouth of West Branch
Sacandaga river, a very small portion only of a diabase dike may
be seen in contact with a syenite-looking rock. This rock is differ-
ent from the others in lacking a diabasic texture and containing
considerable hypersthene (no. 43 of table).

The largest dike, 300 feet long and 30 feet wide, is located about
a mile east of Benson P. O. Its north 70° west strike is exceptional
though it does lie parallel to the foliation of the country rock
which here is closely involved Grenville and igneous gneisses.
Toward the borders the dike becomes very fine grained while
throughout the mass phenocrysts only sporadically occur (no. 39
of table).

Examples of gabbro and diabase

| n
3
oO

| g AeA 2 sh

a i 8 eee ba Pg eee me yl a | ee te

a bo Ses Pten pestis | cen bose foes Pig poe age ant

a em Ay < sha tm fa bee ea ba Ay py a

rg 47 8f3 Ol-Labs 60012. 5 ere. 22 | 10 2|2 3 Tove heageetee [ees tethces
5 48 8h3 Ol.-Lahs. Gare s eink +s Fa) ERE foe 3 I RTS esse
‘| 49} gbt Ol.-Lab. 60 |...... 25 lore, 2 | 2 3 ee oo eee
oO 50 | 8f2 | OL-Lab. 60 |...... 22 | 10 2 } 5 DP eres rcesak es
51 14j3 Qi-tab; 60 lle iees. Zp eee te Tee oscar neve eee he lite oak arene oe
52 rom4 COE EE I ie ac as be eaten As | 5 1 pH aaa Ba | ANE SS a
39 Im1I3 Ol.-Lab. 60 C's a \ EA) | om er 8/5 MG Er lispare pss Was ee al lta are, ae
PA 40 6er Ol.-Lab. 65 BGs tere: evsid« heroes Jaretate 2O Le VP tact Le acre eon ltt weer:
2 41 9b7 Lab. 70 Brisas oi Vevare xilte aushs 20 Wed Pave Weel a eceeeraul te tonetei antec tebe
5 43 8l2 Ol -=Laby sor lice. sc 25. |, BOM. atuttassiers iB Roel User he cad Pee Oe
ee” EL) Sees Lab. 40 CLS Eee) aa Pa asic EOP Glee cwpas bitte ahs Ring x I5
A| 46 7€3 Lab. 60 Co id | rag (Ro TAS OE ed Nee HARE DLE” |ledace tal Petncg guns

32 NEW YORK STATE MUSEUM

Foliation

All the Precambric rocks, except the diabase, show more or less
well-developed foliation. Details have already been given, and only
certain broader features are here considered.

In general, the most feldspathic rocks, such as anorthosite-gabbro
and certain basic phases of the syenite, are least gneissoid because
of a lack of minerals favorable for development of that structure,
while the granites, at the other extreme, rich in biotite and quartz,
are usually very gneissoid. Exceptions are, however, by no means
wanting, so that the degree of foliation among rocks of similar
composition may differ widely.

The more representative dip and strike observations selected from
many notebook records are plotted upon the accompanying geologic
map. One of the most notable features is the remarkable uniformity
of strike over the whole quadrangle, with very few exceptions
ranging from east-west to northeast-southwest. Scarcely less uni-
form are the directions of dip which in the great majority of cases
is southward. The angles of dip range from low to high but with
dips of from 30 to 50 degrees distinctly prevalent. Many times .
the amount of dip can not be determined.

Other important features, rather common to the whole Adiron-
dack region, are the practical coincidence of stratification and folia-
tion surfaces in the Grenville; the nearly perfect parallelism of
these to the foliation of the surrounding rocks; and the most in-
variable arrangement of Grenville masses with long axes parallel
to the foliation.

PALEOZOIC ROCK-OUTLIERS
The outlier at Wells

At Wells is the largest and most interesting of all the Paleozoic
rock outliers in the Adirondack region. The nearest outcrops of the
general Paleozoic area are at Northville nearly 13 miles (air line)
from the most southerly exposures in the outlier.

The first mention of this outlier was by Emmons in 1842 but
no description was given. He said: “At Hope I found a few
acres of Trenton rock, loaded with the usual fossils; and to the
south a few miles, the Calciferous, each in place.” As Professor
Kemp has said,» Emmons must have meant Wells instead of Hope,
since no such Trenton exposures occur at Hope.

t Geology of the Second District 1842, p. 417.

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GEOLOGY OF LAKE PLEASANT QUADRANGLE 33

In 1893 Darton! made a generalized structure section across
the valley at Wells and made some brief statements regarding the
outlier.

In 1897 and 1898 Ruedemann,? in presenting arguments for the
existence of an Ordovicic ocean current, referred to the Wells out-
lier in his second paper expressing his belief that the Paleozoic
strata of the outlier occupy a fault valley or “graben” and that
the strata originally belonged to a continuous mantle of sediments
which covered the southern Adirondack region. Neither map nor
structure section were presented by Ruedemann.

The only detailed study of this outlier heretofore presented is
by Kemp, Newland and Hill in 1898.2 Many important points are
brought out in this paper (see references below) but, since the
Lake Pleasant sheet was not then published, a sketch map only,
showing the principal outcrops of Paleozoic rocks, accompanied the
report. No structure section was attempted.

During the summer of 1912 the writer made a very detailed
survey of the vicinity of Wells and as a result of this work data
were obtained for the preparation of the first detailed areal geological
map of this outlier, published in connection with this bulletin.
The accompanying structure sections across the valley at Wells are
also the first to be based upon a detailed survey.

Of all the known outliers in the southern Adirondacks, the most
complete Paleozoic section is shown in this one at Wells, the fol-
lowing formations all being well represented: Potsdam sandstone;
Theresa transition beds; Little Falls dolomite; Lowville limestone;
Trenton limestone; and Canajoharie (Trenton) shale. The section
is not perfectly continuous but, as nearly as can be determined,
the total thickness of the Paleozoic strata lies between 486 and 564
feet, with 500 feet probably close to the actual thickness.

As shown on the accompanying sketch, the strata comprise
an inverted V-shaped area of rocks bounded on each side by a
prominent fault with a minor fault parallel to the major ones passing
through the village of Wells. These faults are described in a suc-
ceeding chapter. The greatest length of the outlier is 4% miles
along the western side; its greatest width is 114 miles through the
village ; while its area is a little over 3 square miles.

173th Annual Rep’t, etc., N. Y. State Geol. for 1893, p. 608-9.
2 Amer. Geol., June 1897; Amer. Geol., Feb. 1808, p. 75.
318th Annual Rep’t N. Y. State Geol., 1808, p. 145-52.

34 NEW YORK STATE MUSEUM

Potsdam sandstone. The best exposures of this rock are to be
seen about 300 yards directly east of the Catholic church and high-
way bridge in the southern end of the village. No one of the
several good outcrops shows a thickness of more than 6 or 8 feet,

= Canajoharie Black River-Trenton f——) Little Falls
te

shale limestones olomite

[_——— Potsdam- Theresa xxx 2 APY,<] Granitic
1 sandstone & dolomite [5% X] Syenite syenite

Precambric HORIZONTAL SCALE VERTICAL SCALE
— | ee
- tjrock 0 MILE 1 ° MILE 's

Fic. 1 Detailed structure section along the line AA (see geologic map)
across the valley (Paleozoic rock outlier) at Wells

though, considering the positions of the outcrops, a thickness of
no less than 20 feet is certainly shown here. As nearly as could
be determined, the 1040-foot contour marks the summit of the
Potsdam whose beds lie in almost horizontal position though with
a very slight westerly dip. Immediately above and below the
river bridge, granite outcrops in the river bed at altitude 980
feet, but no Potsdam is there visible.

The rock is a rather pure, white to light cream-colored, thin
to rather thick-bedded sandstone. Cross-bedding and _ ripple-
marks are common but pebbles are scarce. The quartz grains are
well rounded. Upward the rock grades into the Theresa tran-
sition series due to the appearance of dolomite beds.

In 1898, according to Kemp, the Potsdam was visible in a pit,
8 or 10 feet deep, immediately east of the hotel (Wells House)
at the northern end of the village. This exposure could not be

GEOLOGY OF LAKE PLEASANT QUADRANGLE 35

seen at the time of the writer’s study, but its presence, together
with the practically horizontal position of the strata, make the
mapping of the Potsdam here quite certain.

Where the branch road comes close to the river about four-
fifths of a mile north of the north end of the village, there is
a small sandstone outcrop belonging with either the Potsdam
or the Theresa, most likely the former. The rock is a two-foot
bed of white sandstone with a westward dip of Io degrees. As
far as one-half of a mile northward from this outcrop along
the same road, several large angular fragments of sandstone were
noted.

Along the river west of the village no ledges of rock of any kind
occur, though we have every reason to believe that the Potsdam
occurs there under cover of Pleistocene and later Paleozoic strata.

The Potsdam almost certainly comes against the north base of
West hill but heavy drift conceals all ledges there.

Theresa beds. These beds are distinctly transitional in char-
acter between the Potsdam sandstone and the Little Falls dolomite.
They consist of alternating sandstone and dolomite beds, the former
being in every way like the Potsdam sandstone and the latter like
those of the Little Falls dolomite to be described next. Numerous
exposures may be seen along the face of the rock terrace just east
of the village. No single exposure shows a thickness greater than
10 or 12 feet but, since all are well distributed between the 1040 and
1100-foot contours and the strata show only a very slight westerly
dip, we can be sure of a total thickness of 60 feet for these beds.
The thickest dolomite bed noted was 14 inches. Near the fault at the
southern end of the area of Theresa, the beds strike north 30°
east and dip 20° west, which is doubtless due to the updrag effect
along the fault. Northeast of the village no outcrops could be found,
but there can be no doubt of the existence of the Theresa there as
shown on the map. No other outcrops of this formation occur
within the valley, but if the Pleistocene deposits were removed it
would outcrop as a practically continuous belt along most of the
length of the outlier to the west of the small fault in the valley
bottom.

Little Falls dolomite. The only exposures of Little Falls
dolomite are to be found capping the rock terrace just east of the
village. There are so many outcrops that much of the area shown
on the map is solid rock at the surface, the dolomite beds showing
only a very slight westward dip. Since the outcrops range from

2

36 NEW YORK STATE MUSEUM

the 1100 to the 1160-foot contour, we have here a thickness of
60 feet for the Little Falls formation with the summit not shown.
The actual thickness of the dolomite can not be determined, but
maximum and minimum limits may be fairly well fixed by con-
sidering the thickness of strata intervening between the bed of sand-
stone (already described) outcropping four-fifths of a mile north
of the north end of the village and the Trenton limestone in the
quarry west of this sandstone. The dip of both sandstone and
limestone is 10° west, with a horizontal distance of about 1150 feet
between them. The thickness of intervening strata is therefore
204 feet. Now if we subtract 60 feet for the known thickness of
the Theresa and 20 feet for the known minimum thickness (see
below) of the Black River limestone, this leaves 124 feet which
would be the thickness of the dolomite if the sandstone bed above
referred to lies at the summit of the Potsdam. If it lies at the
bottom of the Potsdam, then a thickness of about 50 feet must be
deducted fromthe 124 feet to leave 74 feet for the thickness of
the dolomite. Thus we conclude that the thickness of the Little
Falls dolomite lies between a maximum of 124 feet and a minimum
of 74 feet, with 100 feet probably not far from the actual thickness.

Perhaps the best single outcrop which may be taken as typical
of the formation lies due west of the cemetery and near the base
of the formation where a thickness of 10 feet of dolomite beds is’
shown (see plates 4 and 5). The beds range in thickness up to 2 feet
and contain numerous smali cavities usually lined with dolomite
and clear quartz crystals of the common types so often found in
this formation in northern New York. Sometimes the cavities are
filled with white calcite. Scattered through the bluish-gray dolomite,
which has a fine-grained crystalline appearance, are many small,
water-worn silica grains, so that the rock is really a. siliceous
dolomite. The ledge is divided into numerous small blocks by
well-defined nearly vertical joint planes. Some of the dolomite beds
near the summit of the rock terrace contain streaks of chert.

No fossils were found in the Potsdam, Theresa, or Little Falls
formations.

Absence of Beekmantown and Chazy limestones. Within the
Wells outlier there is no direct evidence for the presence or absence
of the limestones of the Beekmantown or Chazy formations. Heavy
Pleistocene deposits cover the critical places which might show such
rocks. These formations are not represented, however, except by
the Tribes Hill limestone in the Mohawk valley region and since
even the Tribes Hill practically does not occur within the Broad-

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W. Ve Miller, hoe
A detailed view of part of the outcrop of Little Falls (Cambric) dolomite

shown in plate 4

GEOLOGY OF LAKE PLEASANT QUADRANGLE 37

albin and Saratoga quadrangles, we may be reasonably certain that
neither the Beekmantown nor Chazy is represented in the Wells
outlier. Thus the very distinct unconformity between the Little
Falls dolomite.and Black River limestone of the Mohawk valley
is also shown at Wells.

Black River limestone. In actual outcrop the Black River
series of limestones is represented wholly by the Lowville, including
an upper, dark, dove-colored, cherty limestone which is probably
to be classed with the Leray member of the Lowville. The only
exposures occur along the small creek which cuts through the
southern end of the narrow belt of Black River-Trenton limestones
shown on the geologic map. The beds strike east-west and dip
north 10°. In the creek just east of the quarry the following sec-
tion was measured:

Pte in
fst tenton, mrespone- wit fOSSts —— Im Sit? Cscoec de cn dae new dw « 3
Se see IVETE ce) Ps a ee ok ee SAMs OL a Gilg wie saree we 20
5 Dark, dove-colored limestone with smooth fracture. Rather
massive, but with occasional stratification planes visible. Con-
tains a distinct layer of black chert. Leray? limestone....... 6
4 Smooth, black limestone in layers from 1 to 4 inches thick and
Mme tin Goalie parties, -Towvilley 3. os essen Ok ces oa We elale'e 2 AE 6
3 Smooth, dove-colored limestone fairly well separated into layers
from ¥% to 8 inches thick. Lowville............. A TA NR at 4
2 Smooth, dove-colored limestone layers with small dove-colored
Peomensou mmestone.” Lewvilles i0 ss core ie eek wba ena tb tees 3

I Dove-colored limestone with large and distinct vertical tubes.
(Phytopsis tubulosum). Stratification planes divide
the mass into layers several inches thick. Lowville............ 2
Bottom of creek.

Thus a thickness of 16 feet and 9g inches of Lowville, including
the Leray? layer with chert, is exposed but with neither top nor
bottom shown. The exposure is a small one and no fossils except
Phytopsis tubulosum were found. Because it answers
so well to the descriptions given by Cushing? and Ruedemann,’ the
six-foot cherty bed is thought to represent the upper or Leray
member of the Lowville.

If the Amsterdam limestone is present it should come between
the cherty bed and the Trenton, but this part of the section is com-
pletely concealed so that the presence or absence of the Amsterdam
can not be determined.

1A, J. S., Feb. 1911, p. 139-42.
2N. Y. State Mus. Bul. 145, p. 85-86.

38 NEW YORK STATE MUSEUM

Near the north end of the belt of Black River-Trenton limestone
shown on the geologic map, and one-sixth of a mile a little east
of north of the limestone quarry, a number of large angular chunks
(2 to 8 feet long) of Trenton and Lowville limestone were found.
These clearly indicate close proximity to concealed ledges of these
rocks. If the Pleistocene deposits were removed the Lowville would
certainly be seen as a continuous exposure within a8 belt mapped
as Black River-Trenton.!

Trenton limestone. The Trenton limestone is wholly confined to
the west side of the river, the best place for the study of the forma-
tion being three-fourths of a mile north of the north end of the
village and in the immediate vicinity of the quarry there shown on
the map. The rock may be seen in the small quarry, in a big ledge,
and in large, loose blocks. In the quarry the rock is rather thin-
bedded, very fine-grained, dark-colored limestone with very thin
shale partings and numerous fossils. A thickness of about 8 feet
is shown. The strike is north 50° east, dip 10° west.:

The big ledge which lies about 30 or 40 rods southwest of the
quarry is some 50 or 60 feet long and shows a thickness of 10 feet
with strike and dip practically as in the quarry. The following sec-
tion is modified after Kemp, Newland, and Huill:°

5 Rather thin-bedded, fine-grained, black limestone with thin shale ft- im.
partings and abundant ftossils...7 4.2 eee ee ee eee 2

4 Heavy-bedded, gray, crystalline limestone rich in fossil fragments.
Contains numerous sand grains and occasional pebbles of Pre-

eambric Tock “25 eas on.8 dew oe ee ee ee ee ee yi 6)
3. Hard, coarse, crystalline, gray limestone in eight layers with many
well-preserved fossils 33: sis ne.dth ean tice, S ee ere ae eee eee Se 6
2: > Dark gray, fine ‘crystalline limestonen:.2. on rare eee eee ee I
1 Hard, crystalline limestone with abundant brachiopods........... I

Pebbles, up to 3 inches across, of a smooth dove-colored (Low-
ville?) limestone are quite common in this section. As Kemp says ®
“Layer number 4 is a most remarkable rock, being a limestone but.
containing large quantities of quartz sand and in places large pebbles
of the old crystallines. The sand under the microscope is mostly
well rounded and abraded, but some grains are angular.’ Many

1The Trenton limestone is stratigraphically more closely related to the
Canajoharie shale than to the Black River limestone, but because of the
thinness of the two limestone formations it has seemed best to represent
them together upon the geologic map.

2N. Y. State Geol. 18th Annual Rep’t, 1898, p. 149.
3 Op. cit., p. 150.

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9 aed

W. J. Miller, photo
Detailed view of an outcrop of Lower Trenton (Glens Falls) limestone

one mile due north of the northern end of the village of Wells

GEOLOGY OF LAKE PLEASANT QUADRANGLE 39

such pebbles of quartz and granitic gneiss were noted by the writer,
some of them being as much as 4 to 6 inches long. The presence
of the pebbles and sand grains in the otherwise typical Trenton
limestone is a puzzling phenomenon and the only satisfactory ex-
_ planation which occurs to the writer is that suggested by Kemp
when he says?: “The pebbles and sand were derived from the
neighboring crystallines and may have been mixed up with the lime
by floating ice.” The limestone of this section (ledge), except for
the uppermost zone number 5, differs from that of the small quarry
in being generally crystalline and devoid of shale partings. Judging
by field relations, the quarry limestone is regarded as overlying that
of the big ledge and hence we can be sure of a thickness of no less
than 14 to 16 feet with neither top nor bottom shown, though the
full thickness is probably not over 20 feet.

Just south of the big ledge there are many large, angular, loose
blocks of the limestone, each of eight or ten of these being Io or
12 feet across and 6 to 8 feet thick. In one block 6 feet thick,
pebbles of smooth, dove-colored limestone occur in almost every
layer. These limestone pebbles appear to have been derived from
the underlying Lowville since the Trenton rests by unconformity
upon the eroded surface of the Lowville.

From materials collected by the writer, Doctor Ruedemann has
determined the Lower Trenton age of this limestone which con-
tains the following fossils: Streptelasma corniculum,
Prowecomudid “aitetwata | Naiines.guina «dé l
toidea, Plectambonites sericeus, Dalmanella
Perici ia, RIV UCHOLtr cinta ine giv a lve, Pach ya
Pe eAv teu bay itorimotoind ch. es ra-cilis,. Ortho-
Peer et fice ih) Liospina ~ ch -benticularirs,
Peperaitta tapmlites, 1sotel us iragment, and Iflae
nus sp. fragment.

At the southern end of the belt of Black River-Trenton limestone
shown on the geologic map, and west of the southern end of the
village, there are many loose blocks of Trenton limestone which, as
already stated, indicate concealed ledges close by. After the covered
interval (see above) of 20 feet above the Lowville section here, a
few feet of Trenton appears to be in place and this is the only case
of the kind. A few rods down the creek from the quarry and the
Lowville section, hard, limey, black shale marks the base of the
Canajoharie shale formation. This shale and the nearby Lowville

1QOp. cit., p. 152.

40 NEW YORK STATE MUSEUM

limestone both strike east-west and dip northward from Io to 20
degrees, the field relations being such that it would not be possible
for a thickness of over 20 to 25 feet of Trenton to intervene.

Where the little stream coming down frorn Mount Rouge crosses
the limestone belt (see geologic map), there is a small quarry also
showing a few feet of hard, dark, limey shale or shaly limestone
at the base of the Canajoharie or the summit of the Trenton, hence
we can be sure of the mapping at that locality.

Canajoharie (Trenton) shale. As shown on the geologic map,
the Canajoharie shale is wholly confined to a single area on the
western side of the valley, it being bounded on the west by the fault
and on the east by the narrow belt of Black River-Trenton lime-
stones. The typical rock is always black, distinctly stratified, some-
what calcareous, and thin-bedded, the maximum thickness of layers
noted being 5 or 6 inches. Toward the base of the formation the
rock is much more calcareous and not so black, so that it might more
properly be called a very shaly or impure limestone.

Good exposures of the shale occur along the small stream which
comes down from Mount Rouge. Within a few hundred feet of
the fault there is a good outcrop, showing a thickness of 15 to 20
feet, rich in fossils, and with strike north 50° east and dip 20°
east. This sharp eastward dip is the updrag effect produced at the
time of the faulting. At a point about midway between the fault
and the limestone belt an axis of a distinct syncline is crossed (in
the creek) because eastward from this point several exposures
show a gradually increasing dip of from 5° to 10° to the west. In
the small quarry (already mentioned) at the edge of the limestone
belt, the shale is very limey and with fossils much like those of
the Trenton limestone so that this rock clearly belongs either at
the base of the Canajoharie or at the summit of the Trenton.

Along the next stream course to the south, which comes down
from Mount Orrey, the greatest thickness of shale occurs. About
450 feet from the fault there is a good outcrop with numerous
fossils. It shows strike north 60° east and dip 15° east. Then
comes an interval, and about 1000 feet from the fault a more or
less continuous exposure begins and extends several hundred feet
along the creek. It shows a strike north 50° east, dip 5° west, and
a thickness of 35 or 40 feet. Thus a synclinal axis is also crossed
here which is doubtless the same as the one already described as
crossing the creek just to the north. This syncline is well shown in
the accompanying structure section. The quarry (see map) north of
the creek and close to the road, shows a thickness of 20 feet of not

Plate 8

wh

pan

a ‘4

~

¥ i. ‘ art
ee

at

: W. J. Miller, photo
An outcrop of Canajoharie (Trenton) shale in a small quarry near the

road one-half of a mile west of the village of Wells. The tilt of the shale
beds is clearly shown

se

ar

GEOLOGY OF LAKE PLEASANT QUADRANGLE 4!I

very fossiliferous black shale with strike north 40° east and dip
10° west (see plate 8). Considering the angle of slope on which
the shale outcrops as 5°, a distance of 1300 feet, and an average
dip of 7°, a thickness of about 275 feet of shale lies along the brook
between the Black River-Trenton limestone belt and the synclinal
axis.

The only other shale outcrop occurs in the north bank of the
creek which comes down from the north side of Mount Dunham and
only a few rods below the quarry and Lowville section above de-
scribed. This shale is hard and limey, with strike east-west, dip
20°, and it must lie practically at the base of the Canajoharie.

Doctor Ruedemann has kindly determined the following fossils
from shale specimens collected by the writer: Diplograptus
smplexicaaiis, Climacopraptus putillus, Lin-
Sula cCurta, Rafiinesquina alternata (small), .Dal-
manella testudinaria, Plectambonites sericéeus
(small), Glossina trentomensis; Orthoceras hud-
sonicum Primitiella wnicornis and Calymmene
senaria.

Concealed Cambro-Ordovicic strata. A considerable area
(specially colored on the map) of the Paleozoic strata is concealed
under Pleistocene deposits, but judging by the distribution, thick-
ness, and structural relations of the various known formations, we
may be practically certain that all this area, except toward the north
end, consists of Cambric ‘strata. ;

Between the north base of West hill and the limestone belt, the
Potsdam, Theresa and Little Falls formations must lie in regular
order with northward dip. From the limestone-shale areas eastward
the Little Falls dolomite, with westward dip, must extend almost,
if not quite, to the minor fault through the village.

The complete failure of outcrops in the northern portion of the
outlier causes uncertainty regarding the distribution of the forma-
tions there, though the Ordovicic limestones and shale quite certainly
reach farther northward than shown on the map.

The Outlier near Hope

General statements. This interesting outlier, here described for
the first time, occupies the Sacandaga valley bottom between 1 and
3 miles northeast of Hope post office. It is barely possible that
Emmons noted the occurrence of Little Falls dolomite here in his
study of the ‘ Geology of the Second District.” In the quotation

42 NEW YORK STATE MUSEUM

from his work already given (see page 32), his mere mention of the
so-called Calciferous (Little Falls dolomite) may possibly refer to
the occurrence near Hope, though he more likely meant the outcrop
of this rock in the valley at Wells where it lies a mile or more south
of the big Trenton exposures. The dolomite near Hope lies over
6 miles by air line and nearly 8 miles by road south of the Trenton
at Wells. Also the big exposures of dolomite at Wells would more
likely have been known in the early days. At any rate, no descrip-
tion of the interesting Paleozoic rock outlier near Hope has ever
been given.

This outlier is considerably smaller than the one at Wells and less
satisfactory to represent upon the geologic map. It lies 8 miles
(air line) northeast of Northville at which place occur the nearest
outcrops of the general Paleozoic area. The outlier, as shown on
the map, has a length of nearly 3 miles and a greatest width of
half a mile, though admittedly exact boundary lines can scarcely be
drawn. The character of the valley bottom and the general struc-
tural relations strongly suggest a Paleozoic rock area fully as large
as indicated on the geologic map. Actual outcrops are all confined
to the narrow belt as mapped, the rest of the area being wholly con-
cealed under Pleistocene deposits. This mass of Paleozoic strata
has been sharply down-faulted against the Southerland mountain
mass, the maximum displacement of the fault being fully 1000 feet.
On the east side of the valley the topography and the straight line
of outcrops of Precambric rocks at the base of the steep slope very
strongly suggest the existence of a fault there. If so, this outlier,
like that at Wells, is of the nature of a “ graben.” |

Potsdam and Theresa beds. Potsdam sandstone is nowhere
visible, while the Theresa beds are seen in only two small outcrops
as indicated on the geologic map. One of these, lying just east of
the road, is 30 or 40 feet long and shows one bed of sandstone and
one of dolomite with strike north 20° east, dip 20° west. This ex-
posure, because of the sharp difference in dip between it and the
close-by Little Falls dolomite, is probably separated from the dolo-
mite by a minor fault. The other outcrop barely shows at the
western base of the belt of Little Falls dolomite (see map).

Little Falls dolomite. The principal outcrops are of Little Falls
dolomite and they are wholly confined to the single belt with strike
north 10° east as shown on the geologic map. Of these, the best
exposure lies just at the river’s edge on the south side where the
dolomite beds strike north 5° east and dip 16° west. For 60 yards

GEOLOGY OF LAKE PLEASANT QUADRANGLE 43

directly across the strike the beds outcrop continuously so that a
thickness of some 51 feet is shown. The beds are generally heavy,
ranging up to 2 feet in thickness, with the upper two-thirds of the
beds rich in light to dark gray chert which is often arranged in
very irregular thin layers, but at other times it is irregularly
scattered. From this ledge southward for about 100 yards a 10 foot
wide outcrop continues with the same dip and strike.

Northward, within the belt as mapped, the first dolomite exposure
occurs about one-fourth of a mile from the river and thence for
one-half of a mile there is a practically continuous exposure, though
at no one place is a thickness of more than 6 or 8 feet visible. Along
this slope, however, the outcrops are so arranged that no less than
30 feet of thickness of dolomite is present with a slight westward
dip. None of these dolomite exposures are visible from the road.

Black River limestone. In an old quarry close to a limekiln, a
small wedge of Lowville limestone (see map) is sharply faulted
against the dolomite. The fault plane is clearly visible for a few
feet in the quarry and a thickness of only 6 or 7 feet of limestone
is shown in place. The rock is only sparingly fossiliferous, the
Tetradium tubulosum proving the limestone to be of
Lowville age.

Significance of the Paleozoic rock outliers

These and other outliers (see below) of the southeastern Adiron-
dack region afford positive evidence that the waters of the early
Paleozoic sea spread over part or all of the region. Did these waters
occupy distinct embayments or estuaries as has been suggested or
did they form a more regular shore line?? Along the eastern side
of the Adirondacks where the topography was moderately rugged,
such embayments were quite likely physiographic features of some
importance due to a drowning of the valleys which had been cut out
along the belts of weaker Grenville strata. In the southern Adiron-
dacks, however, the evidence is decidedly against the encroachment
of the late Cambric sea by setting up anything like well-defined
embayments or estuaries extending into the area of Precambric rock.

The outliers of Paleozoic rock in the southeastern Adirondacks
are of first importance in this connection. All the definitely known

1For a rather full discussion of the “Early Paleozoic Physiography of
the Southern Adirondacks” see paper by the writer in N. Y. State Mus.
Bul. 164, 1913, p. 80-04.

44 NEW YORK STATE MUSEUM

outliers well within the Precambric rock area of this region are
given in the following list:

1 A small exposure of Potsdam sandstone near the scutes
corner of the Elizabethtown quadrangle and near the village of
North Hudson. |

2, 3, 4 Three outliers of Potsdam sandstone along the eastern
side of the Paradox Lake quadrangle.

5 The Little Falls dolomite outlier (probably with underlying
Potsdam) at Schroon Lake village, Schroon Lake quadrangle.

6 A small outlier of Potsdam sandstone one and one-half miles
west of the village of North River in the northeastern corner of
the Thirteenth Lake quadrangle.

7 A small outcrop of Theresa sandstone and dolomite (prob-
ably with underlying Potsdam) near the northern border of the
Luzerne quadrangle and one mile due west of High Street village.

8 The Wells outlier in the Lake Pleasant quadrangle.

g The Hope outlier in the Lake Pleasant quadrangle.

Of these, numbers 7 and 9g have been discovered by the writer
within the past four or five years.

In addition to these, there are certain other outliers close to the
main body of Paleozoic strata.

It is important to note that all the outliers above ened as
occurring well within the Precambric rock area, lie on the down-
throw sides of faults. In the case of the Wells outlier, the valley
is of the nature of a “ graben” where the block of Paleozoic rock
has been dropped down no less than 1600 feet to its present posi-
tion. Thus there appears to be no escape from the conclusion that
the valleys containing these outliers have been largely produced by
faulting, and that the Paleozoic strata formerly lay at a much higher
level, that is the general level of the Precambric rock surface.
Simple down faulting of the Paleozoic strata has often carried masses
of these so far down that remnants have been protected from com-
plete removal by subsequent erosion. As is well known the southern
Adirondack region was, by the beginning of the Potsdam, worn
down to a peneplain upon whose surface only a few very minor
irregularities existed. This being the case, anything like prominent
embayments or estuaries could not possibly have existed. Another
argument decidedly against the embayment idea comes out of the
character of the sediments within the outliers. Thus the dolomite
in the Schroon Lake and Wells outliers is a distinctly marine forma-
tion of exactly the same character as that of the general Paleozoic

GEOLOGY OF LAKE PLEASANT QUADRANGLE 45

rock area. Or again, the Canajoharie black shale at Wells is both
faunally and lithologically distinctly marine and precisely like that
of the Mohawk valley. Estuarine deposits would show certain dis-
tinct local variations and hence the very uniformity of sediments
in the outliers precludes the possibility of deposition in estuaries.
Thus we are forced to conclude that when the early Paleozoic sea
encroached upon the southern Adirondacks, the shore line was fairly
regular, with possibly some very small local embayments along the
eastern side, and that a general mantle of sediments was deposited
over the whole southeastern Adirondack region.

FAULTS
General statements

The whole area of the quadrangle is cut to pieces by many nor-
mal faults, about forty of which are shown on the accompanying
geologic map. In certain cases where the presence of the faults
is not regarded as wholly conclusive, they are represented by broken
lines. It is certain that other, chiefly minor, faults exist but because
of insufficient data they can not be shown on the map. Most of
the prominent faults form a distinct group with an average strike
north-northeast, thus harmonizing with the general faulted region
of the eastern and southern Adirondacks. Another, though less
important group, shows an average west-northwest strike or at right
angles to those of the major group. The few remaining faults strike
about north-south or east-west. As a result of this arrangement
of earth fractures, many fault ridges, troughs and blocks have been
developed.

Wherever the fault surfaces are exposed they are seen to stand in
practically vertical position so that there can be little doubt that all
are vertical faults, which is quite the rule for the eastern Adiron-
dack and Mohawk valley regions. In the igneous and metamorphic
rocks of the quadrangle it is impossible to work out the elements
of the faults in anything like such detail as could be done in typical
stratified deposits. Exact amounts of displacements can never be
determined though approximate minimum figures can often be given.

For a detailed discussion of the age of Adirondack faulting, the
reader is referred to the work of Cushing.’ ’ Suffice it to say here
that some of the faulting is known to have occurred in Precambric
time, though no positive examples were noted within the quadrangle ;

1N. Y. State Mus. Bul. 95, p. 403-12; 422-24; 428-20.

46 NEW YORK STATE ‘MUSEUM

some probably occurred at the time of the Taconic Revolution (close
of the Ordovicic) or the Appalachian Revolution (close of the
Paleozoic) or both; while extensive faulting certainly occurred
toward the close of the Mesozoic or even later. Any important
topographic effects produced by Paleozoic fauiting must have been
largely obliterated during the long erosion interval which resulted
in the production of the Cretacic peneplain of the Atlantic coast.
Most of the existing major topographic features of -the quadrangle
have been produced by faulting along either old or new lines since
the development of the Cretacic peneplain as proved by the steep
scarps even in homogeneous rocks and by the frequent distinct tilt
of the fault blocks which are only moderately affected by erosion.

The following criteria have been used in recognizing the faults
of the quadrangle: (1) long, straight, distinct ridges irrespective of
rock character and with steep side or sides; (2) the strike of most
of these ridges at high angles across the pronounced foliation of all
the rocks and the belts of comparatively weaker Grenville and mixed
gneisses; (3) very steep to actually vertical scarps even in perfectly
homogeneous rock masses; (4) occasional distinct downtilt of earth-
blocks away from the scarps; (5) distinct fault-breccia or crushed
-rock zones of common occurrence; and (6) updrag effect in the
black shales in the case of the fault along the western side of the
Wells outlier. ;

Wells outlier faults

Elbow-Three Ponds Mountain fault. Considering definiteness,
length, influence upon topography and relation to the Paleozoic rock
outlier at Wells, this is the most important fault of the quadrangle.
It has a north-northeast strike, length of 15%4 miles across the
eastern side of the quadrangle, and continues northeastward along
the East Branch Sacandaga river for over 12 miles to beyond
Oregon (Thirteenth Lake sheet). Its total length is no less than
28 miles with very distinct influence upon the topography along the
whole line as shown on the contour maps. The downthrow side is
on the east.

Shear zones, parallel to the fault, are finely developed in the bed
of Devorse creek 1 mile south of Blackbridge and in “ The Notch”
at the base of Three Ponds mountain. At the latter locality big
ledges exhibit a brecciated zone several feet wide with angular
fragments of Grenville up to 1% feet across. The Paleozoic rock
outlier at Wells is sharply downfaulted against the high mountain

Plate 9

“W. J. Miller, photo

Looking westward across the valley at Wells from a point just east of the

northern end of the village. The prominence of the fault scarp on the
west side of the valley is well shown

Plate 10

W. J. Miller, photo—
The fault scarp just east of the southern end of the village of Wells
with numerous glacial boulders of Cambric rock in the foreground

GEOLOGY OF LAKE PLEASANT QUADRANGLE 47

ridge just to the west, the shales showing a distinct updrag effect
close to the fault. See figures 1, 2 and 3 and plate 9.

Fig
mbri

ee Ordovicic strata Ca

c strata Mixed gneisses

r= ay 7 XKXKX } vy "
oe | Granitic syenite Syenite Precambric rock

MILE o -MILE

+ Horizontal scale be Vertical scale

Fic. 2 Structure section (along line AA) passsing through Hamilton
Mountain, Mt Orrey and Wells.

Fic. 3 Structure section (along line BB) passing through Mt Rouge,
Wells and to Murphy lake on the Stony Creek sheet.

Within the map limits the greatest throw (vertical displacement)
is alongside the Wells outlier and where the structure section lines
cross it (see map). The altitude of the fault line there is 1200 feet,
while summit of Mount Orrey lies at 2646 feet. This gives a dif-
ference of elevation of 1446 feet, but to this must be added 500
feet which represents the approximate thickness of the Paleozoic
strata just east of the fault. This gives 1946 feet which is the total
amount of displacement now represented in the topography. In
order to get the actual amount of displacement, the thickness of
material removed from the summit of Mount Orrey, since the
faulting began, must be added. We have no good reason to think |
that this figure would be very materially increased on this account.
Thus, all things considered, the actual amount of displacement along
the fault here is no less than 2000 feet. This throw diminishes
rapidly both northward and southward. Thus, at the base of Elbow
mountain it is probably not much over 1000 feet, while between
Mount Dunham and West hill it can not be much over 1500 feet.

48 NEW YORK STATE MUSEUM

South of Blackbridge the throw nowhere appears to be more than
a few hundred feet.

Fault just east of Wells. This fault bounds the Wells outlier
on the east. Its position is very clearly indicated by the topography,
the zones of crushed rock along the river south of Wells, and the
fact that the practically horizontal Cambric strata come so sharply
against the steep scarp of Precambric rock just east of Wells. Its
strike is north-northeast; length 6 miles; and downthrow side on
the west. Considering the thickness of Cambric strata and differ-
ences of altitude on either side of this fault just east of Wells, the
throw there must be no less than 570 feet.

Fault through Wells. ‘This is a minor fracture passing through
the village of Wells and over West hill. It is parallel to the larger
faults just described on either side of the valley. Its position is well
marked by the topography where it crosses West hill and less so
where it passes through Wells. One-half of a mile south of the
road summit on West hill there is a distinct crushed rock zone along
the fault. In a number of wells, 25 to 40 feet deep, in the northern
portion of the village and just west of the fault, no rock was struck,
while just east of the fault as there mapped the rock outcrops and
was also struck in pits just back of both Cochran’s and Hosley’s
hotels in the northern part of the village.

The downthrow side of this fault is on the west and, as nearly
as can be determined by the structural relations of the Paleozoic
strata at Wells and the topographic influence on West hill, the
throw appears to be approximately 100 feet.

Hope outlier faults

Colombe Brook-Cathead Mountain fault. This fault is clearly
traceable along Colombe brook and the eastern bases of Souther-
land, Groff and Cathead mountains. Its downthrow side 1s on the
east and the topographic influence is very pronounced. It bounds
the Paleozoic rock outlier near Hope on the west. Good fault-
breccias were noted in the beds of Colombe and Hatch brooks.
The most prominent scarp is just west of the outlier where it is
very steep and rises almost 1100 feet above the river level. Con-
sidering the difference of altitude of 1060 feet between the summit
of Southerland mountain (1900 feet) and the river level (800 feet)
and the thickness of from 100 to 200 feet of Paleozoic strata at
the base of this mountain, we find that the total amount of displace-
ment is here no less than about 1200 feet. Northward the fault

GEOLOGY OF LAKE PLEASANT QUADRANGLE 49

dies out toward the headwaters of Colombe brook, while southward
along the base.of the Groff-Cathead mountain masses the apparent
throw is from 500 to 8o0 feet.

Dewey Creek fault. Only the southern end of this very prom-
inent fault comes within the map limits and joins the Colombe
Brook-Cathead Mountain fault at the base of Groff mountain. This
fault is fully 15 miles long and its topographic influence is very
pronounced, especially within the Stony Creek sheet where the
scarp rises abruptly from 400 to 800 feet. Its downthrow side is
on the west. Some crushed rock was noted along Dewey creek.

Fault on east side of outlier. The character of the topography
and the very straight lines of outcrops of Precambric rocks at the
base of the steep slope make the existence of a north-south fault
here almost certain, though the evidence is not conclusive. It ap-
pears to have a displacement of no less than 300 to 400 feet with
downthrow side on the west.

Faults within the outlier. A minor fault sharply bounds the
mapped area of Little Falls dolomite on the west. The outcropping
dolomite north of the river forms a fairly distinct scarp. Where
the wedge of Lowville limestone comes against the dolomite, the
fault surface is plainly visible in a small quarry. At this quarry
the whole of the Potsdam and Theresa are faulted out so that the
throw is here about 100 feet. Northward the fault can not be
traced because of heavy drift deposits.

The strong westward dip of the beds in the small area of Theresa
just east of the road is probably due to downfaulting of these beds
against the dolomite as shown on the map, though the relations
are not very clear.

Speculator-Hamilton Mountain fault

A very prominent fault has determined the steep eastern front of
the great Speculator-Hamilton-Swart mountain mass. It strikes
north-northeast along Jimmy creek; the west side of Charley lake;
and through Gilman lake. An important branch bears due north
from the notch just west of Round mountain and has determined the
steep scarp immediately east of the summits of Cutknife and Specu-
lator mountains. Evidences of shearing were noted along this
branch fault and also in the notch just west of Round mountain.
The downthrow side of this fault is on the east with a displacement
along Jimmy creek of fully 1000 to 1200 feet, while the combined
throws of the two branches of the fault east of Speculator mountain
are at least 1300 feet.

50 NEW YORK STATE MUSEUM

Fault at west base of Mount Dunham

The evidence for this short, though important, fault at the western
base of the Mount Dunham-Orrey ridge is largely topographic, the
high, very steep scarp in homogeneous syenite and nearly at right
angles to the strike of the foliation of the rock making the existence
of a fault practically certain. Where the line of fracture crosses
Elbow creek, a crushed rock zone may be seen but the fault can not
be traced north of the creek. Toward the south it terminates very
abruptly against a short cross-fault. A displacement of fully 600
feet is represented with downthrow on the west side.

Gilmantown fault

This well-defined dislocation, with almost due north-south strike,
passes through Gilmantown, along the eastern side of Gilman lake,
and along the western base of Burnham mountain (Indian Lake
sheet). The topographic influence is pronounced. Broken rock
zones were noted in the notch one-half of a mile south of the
northern map limit and along the road two-thirds of a mile south
of Alvord P. O. Only a few hundred feet of displacement appear
to be shown.

Faults in the vicinity of Sacandaga lake and Lake Pleasant
Fish-Oxbow Mountain fault. That a fault line passes along the
eastern bases of Fish and Oxbow mountains is proved by the ridge-
like topography with northeast trend or nearly at right angles to
the strike of the foliation in the homogeneous syenite and also by
the presence of a shear zone in the notch one-half of a mile’ due
south of the summit of Fish mountain. The eastern faces of both
Fish and Oxbow mountains are very steep scarps rising about 600
feet each. This fault quite certainly passes across the lake and
along Hatchery brook (Indian Lake sheet). The downthrow side
is clearly on the east. |

Fault on east side of Sacandaga lake. A line of fracture almost
certainly passes along the eastern side of Sacandaga lake and the
western base of the mountain ridge which extends southwestward
from Lake Pleasant village. The evidence is wholly topographic,
though the development of such a prominent ridge with steep
western face at right angles to the other structural features of the
region makes the existence of this fault practically certain. From
Indian Head southward for four miles, the displacement appears
to be no less than 600 to 700 feet. This fault continues into the.
Indian Lake quadrangle along the west base of Oak Hill.

GEOLOGY OF LAKE PLEASANT QUADRANGLE 5!

Speculator village fault. Another fracture with northeast strike
extends through Speculator village, along the west side of Lake -
Pleasant, between Indian Head and Lookout mountains, and nearly
to Fiddler’s lake. The presence of this fault is shown by the pro-
nounced influence upon topography and the crushed zone along
the creek 1 mile southeast of Lilly lake. Through Lake Pleasant
its course is not exactly known, but on the Indian Lake sheet its
course, for some miles, is very plainly indicated by the character of
the topography along the western side of the Kunjamuk valley.

Hamilton Lake fault

This line of dislocation with northeast strike is important because
it bounds the great Speculator-Hamilton mountain fault block on its
west side. Its influence upon the topography is very marked, with
the development of a fault-rift valley. A broken rock zone, indi-
cating nearness to the fault, outcrops on the eastern shore of Hamil-
ton lake. The downthrow is clearly on the west side, and the
amount of displacement from 500 to 800 feet as far north as
Sucker brook. From this latter place northward for a few miles
the position of the fault is not so well marked. On the Indian Lake
sheet its course is plainly indicated by the topography on the eastern
side of the Kunjamuk valley.

Hamilton Lake stream fault

A well-defined line of fracture with strike north 30° east is
traceable from the southern end of Lake Pleasant southwestward
partly along the course of Hamilton Lake stream, thence along the
West Branch Sacandaga river, striking the river just above The
Gorge. Its topographic influence is fairly well marked. Very fine
examples of crushed rock zones occur in the bed of Hamilton Lake
stream below the mouth of Gallup creek and in the bed of the river
just above The Gorge (at the diabase dike).

Piseco Lake fault

The Piseco Lake fault must take rank as one of the most promi-
nent in this portion of the Adirondacks. A brief description is
here given because of the profound influence of this dislocation
upon the topography of the northwestern portion of the Lake
Pleasant quadrangle. It strikes northeast aleng the western side of
Piseco lake, that is, at the foot of Panther and Piseco mountains ;
thence just touching the northwestern corner of the Lake Pleasant

52 NEW YORK STATE MUSEUM

sheet ; and into the Indian Lake quadrangle along the eastern bases
of Willis and Potash mountains —a distance of fully 15 miles. A
bold fault scarp, from 500 to 1100 feet high, marks the position of
the fault. These figures also represent the minimum amount of dis-
placement. The greatest throw is along Piseco lake, and since the
downthrow side of this great fault is on the east we thus find a
ready explanation for the large generally depressed area including
Piseco lake and vicinity as well as the northwestern portion of the
Lake Pleasant quadrangle.

Buck Pond Mountain faults?

The fault on the western side of this mountain mass shows a
scarp which rises very abruptly to a height of a thousand feet and
is one of the finest examples of the kind within the quadrangle.
This fault is probably only a continuation of the Hamilton Lake
fault.

Another fault separates Buck Pond mountain from Swart moun-
tain, the deep narrow trench having been worn out along the fault
line of weakness. One shear zone was noted. With reference to
the Swart mountain mass, Buck Pond mountain is on the down-
throw side.

Whitehouse fault

This important cross-fault bounds the great Speculator-Hamilton-
Swart mountain fault block on the south and strikes west-northwest
through Whitehouse and along the stream which heads near the
north base of Mud Lake mountain (Piseco Lake sheet). Shear
zones were noted along the stream one-half of a mile east of the
map limit and along the river one-fourth of a mile below White-
house. The greatest topographic effect is between Whitehouse and
Jimmy creek where, immediately north of the fault line, the steep
mountain rises 1600 feet. Not all of this, however, represents the
throw of the fault because the large river is here in its Preglacial
channel and hence must have very considerably deepened its channel
along the general line of fracture. This fault appears to end
abruptly against the Jimmy creek fault.

Moose Creek fault

One of the three most prominent cross-faults almost certainly
passes along Moose creek, through Mud lake, and along the upper

1 This is the high, steep mountain just northeast of Whitehouse.

GEOLOGY OF LAKE PLEASANT QUADRANGLE 53

course of Ninemile creek. A shear zone was noted in the creek
about a mile below Helldevil dam. The topographic effect of this
fault is marked with downthrow side on the north. Its amount of
displacement is at least several hundred feet. The continuation of
this fault for some miles into the Piseco Lake quadrangle is clearly
indicated by the topography.

North Branch-Moose Mountain fault

A clearly defined, prominent fault with northeast strike lies along
the eastern bases of Moose and North Branch mountains and Chub
mountain of the Piseco Lake sheet. For 7 or 8 miles the steep
fault scarp rises 400 to goo feet as a bold topographic feature. The
upthrow side of the fault is on the west. The actual displacement
appears to be no less than 500 or 600 feet. An excellent sheared
rock zone was observed in the creek at the base of Moose mountain.

Due to the tilting of the fault block, there is a long, westward
downslope of the several miles from the crest of the scarp to the
Sacandaga river on the Piseco Lake sheet. Only a few small, very
swift streams flow down the fault’ scarp side.

Silver Lake outlet fault

The position of this fault is well marked by the topography and
usual stream adjustment along the line of fracture. The down-
throw side is on the west with maximum displacement no less than
200 feet within the map limits. This fault extends for some 6 miles
southwestward to Pine lake and Pine mountain of the Gloversville
sheet and, along this southern part, the displacement is no less than
500 to 700 feet.

Sugarloaf-Silver Lake Mountain fault

This northeast-southwest fault passes along the eastern bases of
Sugarloaf and Silver Lake mountains and thence along the Sacan-
daga river to near the southern map edge. Its topographic influence
is distinct. Northward, as indicated on the map by the broken line,
this fault is thought to be continuous with the Jimmy Creek fault.
The topographic evidence very strongly favors this view. South-
ward from where it crosses Ninemile creek, the downthrow side is
on the east, but northward, between that point and the river, the
downthrow side is on the west due to the great downsinking of the
fault block between the Whitehouse and Moose Creek faults.
Along the trail at the eastern base of Sugarloaf mountain, there is

54 NEW YORK STATE MUSEUM

a fine display of fault-breccia in the Grenville gneiss. Excellent
broken rock zones occur along the river three-fourths of a mile

south of Meco lake and also 1 mile west of Rock lake. A short °

branch fault passes through Meco lake.

Blue Ridge-Three Ponds Mountain fault

There is strong topographic evidence for the existence of a fault
along the western bases of Blue Ridge and Three Ponds mountains,
but since the evidence is not conclusive, this fault is represented on
the geologic map by a broken line.

Grant-Woods Lake fault

This fault bounds the Groff-Cathead mountain ridge on the west.
It strikes north-northeast along a nearly straight line apparently
joining the Elbow-Three Ponds Mountain fault just north of Groff
mountain. Its presence is clearly proved by the type of topography
and the occurrence of a distinct crushed zone in the notch one-hali
of a mile south of Grant lake. From Grant lake to Woods lake the
displacement is fully 700 to. 800 feet with upthrow side on the east.

Abner Brook fault

This fault branches off the Grant-Woods Lake fault and is
clearly traceable by the topography along Abner brook; thence along
the eastern base of the small mountain west of Benson Center ; and
along the western base of the Pinnacle (Gloversville sheet). The
upthrow side is on the west with a displacement of seme hundreds
of feet. One and one-half miles north-northwest of Benson Center
the fault scarp is over 500 feet high and very steep.

Whitman Mountain fault

A short but important cross-fault lies in the river valley at the
base of Whitman mountain. It appears to terminate abruptly against
the Elbow-Three Ponds Mountain fault on the west and the Colombe
Creek fault on the east. Its topographic effect is very pronounced.
Near its eastern end where it strikes the river, there is a fine large
broken rock zone with strike north 60° west. The fault which
bounds the Wells outlier on the east appears to end abruptly against
this fault.

Other faults

The other faults shown on the geologic map require little or no
description.

——— oe ——

GEOLOGY OF LAKE PLEASANT QUADRANGLE 55

The Mount Orrey-Dunham ridge terminates abruptly on the
south due to a fault scarp. Considering its height (1000 feet) and
steepness, this is one of the finest fault scarps of the quadrangle.

Two miles south-southeast of Wells there is a small fault, with
practically vertical scarp, which rises between 300 and 400 feet
in homogeneous granite.

The minor cross-faults on the south sides of Mounts Rouge,
Orrey, and Dunham respectively, and either side of the summit of
Hamilton mountain also have very steep scarps in homogeneous
rock.

Along Ninemile creek, between the Moose Creek and Whitehouse
faults, there are many crushed rock zones with strike north 10° to
20° east, thus proving that the creek has here carved out its channel
along a fault. Its topographic influence is not great but the upthrow
side appears to be on the east.

The topography suggests a prominent cross-fault with nearly
east-west strike along the northern base of Speculator mountain.
The southward tilt of the great Speculator mountain mass away
from the escarpment harmonizes with the idea of this being a fault
block. No positive evidence for a fault could, however, be found.
Also the topographic evidence for a fault here is not so strong
because the large comparatively depressed area, just north of Specu-
lator, Indian Head and Fish mountains and in part occupied by
the large lakes, lies parallel to the foliation and in a region from
which much weak Grenville (including limestone) has been re-
moved by erosion. Such removal of a large body of comparatively
weak Grenville would in itself account for the existing topography
of this region.

Fault ridges and troughs

A glance at the geologic map will show numerous excellent ex-
amples of fault ridges and troughs. The largest and best defined
fault ridge lies between the Jimmy Creek-Sugarloaf and Elbow-
Three Ponds Mountain faults. Some of the highest points on this
ridge, which is 12 or 14 miles long and from 1% to 3 miles wide
are: Elbow mountain, Mount Orrey, Finch mountain, Three Ponds
mountain, and Blue Ridge mountain. The ridgelike form is best
shown just west of the Wells valley, while the highest portion is
the Three Ponds mountain mass. Only two streams — Elbow
creek and West Branch Sacandaga river — cut across this ridge.

The fault block lying between the Jimmy Creek and Hamilton
Lake faults is also a fault ridge notable for width and height. It

6 NEW YORK STATE MUSEUM

al

is 7% miles long, 3 miles wide, and includes several of the highest
points within the quadrangle. Being a relatively elevated mass
completely surrounded by faults, it is a fine example of a “ horst.”

Among other good fault ridges, though on smaller scale, are the
following: Groff-Little Cathead Mountain ridge; Buck Pond ridge;
Indian Head ridge; and the ridge just west of Hamilton lake.

A fine example of a westward tilted fault block, with steep ridge-
like eastern front, is the Moose-North Branch mountain mass al-
ready described.

Perhaps the most clearly defined of a number of fault troughs
is the valley at Wells. If we include with the Paleozoic rock out-
lier the West hill region immediately southward, we then have a
perfect fault basin because this whole depressed block is completely
bounded by faults (figure I).

The Paleozoic rock outlier near Hope probably constitutes a fault
basin similar to the one at Wells, though smaller.

The relatively depressed area between the Whitehouse and Moose
Creek faults is completely bounded by faults and is hence a fault
basin, being the largest within the quadrangle.

Among other fault troughs of moderate size the best are: the
long depressed block just east of Fish mountain; west of Silver lake
outlet; and east of Abner brook.

On a large scale, an excellent fault trough partly within the
quadrangle is the great depressed block lying between the Elbow-
Three Ponds Mountain and Dewey Creek faults. The area of this
fault trough is about 35 square miles and is somewhat modified by
several intervening fractures. Figure 3 gives a good idea of the
character of the structure of this fault trough.

As already suggested, the whole region lying between the Piseco
Lake and Hamilton Lake faults may, in a broad sense, also be re-
garded as a great fault trough more or less sliced by intervening
faults. On one side the great Panther-Potash mountain mass, and
on the other the Speculator-Hamilton mountain mass each rises to
an altitude of approximately 3000 feet, while the wide intervening
region is decidedly lower evidently due to the downfaulting.

Joining of faults

A feature worthy of special mention is the general tendency of
two faults which bound a given basin or trough actually or nearly
to join at one end of the relatively depressed area. On a moderate
scale this is excellently shown in the case of the Wells valley block,

GEOLOGY OF LAKE PLEASANT QUADRANGLE 57

and on a large scale in the case of the great depressed block
lying between the Elbow-Three Ponds Mountain and Dewey Creek
faults, which join or nearly join a few miles northeast of Griffin
(Stony Creek sheet).

SUMMARY OF GEOLOGIC AND PHYSIOGRAPHIC
EIS TORY +

Precambric history

The earliest known condition of the area of the quadrangle dates
back to the very ancient Grenville times when ocean water covered
all of northern New York as well as vast adjoining areas. That
this condition prevailed for a long time (at least a few million years)
is proved by the great thickness of sediments which were deposited
in that ocean.

Next the great masses of anorthosite, syenite and granite were
intruded into the Grenville strata. Also there was metamorphism
of the rocks and a general elevation of the whole Adirondack region
well above sea level, probably at, or near, the time of the igneous
intrusions. We have no definite knowledge concerning the topo-
graphy of this land mass when it was high above sea level, but we
do know that it underwent erosion for a vast length of time ex-
tending through the late Precambric and even into the early
Paleozoic.

After the great intrusions of syenites and granites came the minor
intrusions of gabbro and diabase, the latter having been forced out
in late Precambric time as shown by the fine-grained and non-
metamorphosed character of the rock now near the surface.

Paleozoic history ?

The long period of erosion above mentioned as beginning in the
Precambric extended to Potsdam time in the late Cambric period
as proved by the fact that the first deposit upon the Precambric
rock surface was the Potsdam sandstone. Some thousands of feet

1Those not especially versed in the science of geology might do well
first to consult the writer’s “Geological History of New York State” pub-
lished as N. Y. State Museum Bulletin 168, particularly chapters 1 to 4
inclusive.

2A recent paper by the writer rather fully discusses ‘“‘ The Early Paleozoic
Physiography of the Southern Adirondacks” in N. Y. State Mus. Bul.
164, 1913, p. 80-94.

58 NEW YORK STATE MUSEUM

of Precambric rock materials must have been removed because the
Precambric rock structures (foliation, folding etc.) immediately
below the Potsdam could have been formed only at great depths.
We also know that this work of erosion progressed far enough to
reduce the whole Adirondack region to the condition of a more or
less perfect peneplain. The character of this old peneplain surface,
upon which the Paleozoic rocks rest, has been carefully studied on
all sides of the Adirondacks, and it is known to be moderately
rough in the northeast and very smooth in the southwest. Within
the Lake Pleasant quadrangle the old peneplain surface has of
course been modified beyond recognition by subsequent elevation,
faulting, and erosion, but from what we know about it within the
Little Falls, Broadalbin, and Saratoga quadrangles, we can be sure
that, during the late Cambric period, there could not have been
more than an occasional knob perhaps 50 or 75 feet high projecting
above the general surface.

This peneplain gradually became submerged under the sea when
the Potsdam, Theresa, and Little Falls seas successively encroached
upon the Adirondack region. As shown by the marine character
and present distribution of the Potsdam, Theresa, and Little Falls
deposits, these waters must have spread over the whole southeastern
Adirondack region including all the Lake Pleasant quadrangle
except possibly the northwestern portion. In the paper above cited
reasons are given for thinking that this late Cambric shore line
passed through, or close to, the northwestern portion of this quad-
rangle.

Toward the close of the Cambric period, a general emergence
of the whole southern Adirondack area brought our region above
sea level as proved by the distinct unconformity at the summit of
the Little Falls dolomite.

During Beekmantown and Chazy times we have no positive evi-
dence regarding the physiographic condition of our region because
rocks of those ages are wholly lacking. If such rocks were de-
posited, and this is unlikely, they were removed by erosion before
succeeding Black River time.

During Black River (Lowville) time the area of the quadrangle
must have been almost, if not quite, all under sea water because of
the presence of such rocks in the outliers at Wells and near Hope.
The distinct unconformity at the summit of the Black River
(Lowville) limestone shows that our region again emerged from
the sea and underwent erosion.

GEOLOGY OF LAKE PLEASANT QUADRANGLE 59

Beginning with the succeeding Trenton time our region, as well
as all the southern Adirondack area, subsided to allow an encroach-
ment of the Trenton sea in which were deposited first the Lower
Trenton limestone (very thin in the Lake Pleasant quadrangle)
and then the Canajoharie (Trenton) shale. During this time the
heart of the Adirondack area almost certainly was not submerged 1
and it may be that this dry land area extended far enough south-
ward to include the northwestern corner of the Lake Pleasant quad-
rangle. At any rate the pebbles and sand grains already described
as occurring in the Trenton limestone near Wells prove comparative
nearness to a land area of Precambric rock while this limestone was
forming.

There is no positive proof that any Paleozoic strata later than
the Canajoharie ever were deposited within the area of the quad-
rangle, though the next succeeding Schenectady shales quite likely
were.

At some time during the middle or late Paleozoic era, there
occurred a great uplift (or uplifts) when the whole Adirondack
region, then largely mantled with sediments, was brought well
above sea level. This upward movement may have been inaugurated
at the time of the Taconic revolution at the close of the Ordovicic,
though it is generally thought that the major uplift occurred toward
the close of the Paleozoic era or at the time of the Appalachian
revolution. This upward movement in northern New York was
unaccompanied by folding, but there was a general down tilting
of the Paleozoic strata to the south or southwest. It is quite pos-
sible that some of the extensive faulting of the quadrangle accom-
panied the uplift either at the close of the Ordovicic or of the
Paleozoic or both.

Mesozoic history

As a result of the great uplift (or uplifts), another vast erosion
cycle was inaugurated and none of the southern Adirondack area
has ever again been covered by sea water. This erosion cycle con-
tinued till the close of the Cretacic period when the area of the
quadrangle was again reduced to the condition of a fairly good
peneplain and the Paleozoic strata were largely removed. No
very definite idea of the character of this peneplain within the
quadrangle can be gained because of subsequent movements and
erosion, but it is known to have extended over much, if not all,
of New York State, southern New England, and the Appalachian

1 See evidence presented in the paper above cited.

60 NEW YORK STATE MUSEUM

mountain district. Also it is well known that this great peneplain
was upraised from 1000 to 3000 feet about the close of the Mesozoic
or beginning of the Cenozoic era.

As above stated (see page 46), there is good reason for believing
that much of the faulting, which has produced the larger existing
topographic features, took place subsequent to the development of
this Cretacic peneplain, and probably at the time of its uplift.

Cenozoic history

The existing surface configuration or relief of the region has
very largely been produced by the faulting and erosion of the up-
raised Cretacic peneplain. Most of the numerous tilted fault blocks
and ridges date from this time, and the streams, greatly revived
as erosive agents, have continued to the present time to carve out
the many channels, especially along fault lines.

Late in the Cenozoic era came the Glacial epoch or Ice age when
all the quadrangle, as well as nearly all the State, was buried under |
a great ice sheet. Many local details of the present topography are
due especially to morainic or glacial lake deposits in the valleys.

- Topographic influence of faults and rock character

The profound influence of faulting upon the topography of the
region is very clearly brought out by an inspection of the accom-
panying geologic map and, after the descriptions of the faults in an
earlier chapter, no details will here be given. Suffice it to say that
nearly all the major relief features, such as the northwest-southeast
mountain ridges and many of the more prominent valleys, are due
to faulting. These ridges have been considerably modified by
weathering and erosion subsequent to the faulting. Aside from these
major features, many stream channels have been developed along
fault lines or zones of weakness.

In contrast with the Adirondack region in general, and the North
Creek region recently described by the writer in particular,’ no
one of the Precambric rock formations may be said to stand out
prominently above the others against weathering and erosion.
Where the Grenville is notably developed in the Adirondacks, it
is the rule for its weaker members at least to occupy the valleys,
but within the Lake Pleasant quadrangle, the Grenville is neither
prominently developed nor does it contain much weak rock such as
limestone. Quartzites and hard gneisses make up the bulk of the

1N. Y. State Mus. Bul. 170,

GEOLOGY OF LAKE PLEASANT QUADRANGLE 61

Grenville, and for this reason the highest parts of such masses as
Three Ponds and Wallace mountains are of Grenville. The syenites
and granites all appear to show about the same resistance to
weathering and erosion.

The Paleozoic strata of the outliers occupy low valleys not so
much because of relative softness or weakness of the rocks, but
rather because they have been dropped down so far by faulting.

DRAINAGE

The Sacandaga river. All the drainage of the quadrangle passes
into the Sacandaga river, which is the most important tributary of
the Hudson river in the Adironda:k region. Two of the three prin-
cipal branches of the Sacandaga head within the quadrangle; the
main stream with sources in Sacandaga lake and immediate vicin-
ity, and the West Branch with sources in the high Three Ponds-
Sugarloaf-Blue Ridge mountain mass of the south-central portion
of the quadrangle.

The Sacandaga river pursues a remarkably anomalous course,
being in fact one of the most interesting rivers of the State in this
respect. Among the anomalous features of special interest are:
the general eastward, instead of southward, course for this part of
the Adirondacks ; the very circuitous course; the crossing of a wide
highland belt of hard Precambric rock instead of flowing southward
in the valley of much softer Paleozoic rock from Northville (Broad-
albin sheet) southward; and the remarkable courses of certain
tributaries such as Kennyetto creek. All these features are well
shown on the accompanying sketch map. The most roundabout
course is pursued by water at the source of the West Branch of the
river, such water traveling a distance of about 88 miles? before
emptying into the Hudson river at Luzerne. Beginning under
Sugarloaf mountain, the West Branch flows southwestward, west-
ward, northward, and then eastward to a point 2% miles below
Whitehouse (Lake Pleasant sheet) where, after making an almost
complete circuit of 28 miles, the river is less than 4 miles from its
starting point (see figure 4). This peculiar course is largely due
to the influence of faults upon the topography, the stream chan-
nels almost wholly having been determined by fault lines of
weakness.

1 This distance includes as nearly as possible many sharp local bends of
the river as shown on the various topographic maps.

62 NEW YORK STATE MUSEUM

From Sacandaga lake to Northampton, the direction of the main
river is quite normal for this part of the Adirondacks, but at

PRECAMBRIC
ROCK

PALEOZOIC
ROCK

|

bi
rf

ul
5
ee

isa ar aa.

STS, TE Vib aeRO, SRE >: AES
{ __-UNOVOTSVE Ae — = as eee fe eee
Ry ETE ee Wes ee AT peng 7

Fic. 4 Sketch map showing the remarkable course of the Sacandaga
river and the relation of the drainage lines to the Precambric and Paleozoic
rocks. The Preglacial Sacandaga flowed southward from near Northampton

into the Mohawk river.

Northampton the sharp turn northeastward is decidedly abnormal.
Before the Ice age the river continued southward through the
Paleozoic rock valley and into the Mohawk river,’ but due to heavy
accumulations of morainic materials across the mouth of the valley
the river has been forced to seek a lower channel across what was
a Preglacial divide between Day and Luzerne. The remarkable

1See figure 10 of N. Y. State Mus. Bul. 153 and also the writer’s paper
on “The Preglacial Course of the Upper Hudson River” in Geol. Soc.

Amer. Bul., vol. 22, 1911, p. 184.

GEOLOGY OF LAKE PLEASANT QUADRANGLE 63

course of the tributary Kennyetto creek is due to a deflection of
the lower reach of the stream down the north slope of the same
morainic dam above mentioned.

Another very interesting drainage feature is the following. Within
the quadrangle, Fawn lake and Sacandaga lake are only half a
mile apart and yet the waters pass off in opposite directions, the
drainage from Fawn lake flowing westward and southward through
Fall stream, Piseco lake, Piseco outlet, and West Branch to its
mouth, or a distance of over 30 miles, before meeting the drainage
from Sacandaga lake.

Lattice drainage. A glance at the geologic map will show that
most of the important stream channels of the quadrangle have
been developed along fault lines of weakness. Professor Brigham
has applied the term “lattice drainage” to a more or less regular
or latticelike system of drainage lines due largely to a development
of stream courses along intersecting faults. The whole area of the
Lake Pleasant quadrangle is a good illustration of such “lattice
drainage,” that portion lying between Wells and Hamilton lake
being particularly good. No doubt other faults than those shown on
the map, especially minor east-west ones, exist, so that the full
influence of the faulting as a cause of the “lattice drainage” is
not brought out. Also the very strong northeast-southwest trend
of the mountain ridges due to faulting and the consequent general
tendency of the little streams to enter the fault valleys at right
angles, helps to bring out the lattice form of the drainage.

GLACIOLOGY

During the Glacial epoch, the area of the quadrangle was buried
under the great ice sheet as proved by glacial marks or striae,
boulders, and morainic deposits. At the time of maximum glacia-
tion, the whole Adirondack region, even including the highest peaks,
as well as practically all the rest of the State, was covered by this
ice sheet.

Ice movement and erosion

As is well known, the general movement of the ice was from
the Canadian region southward over New York State. Across the
quadrangle the direction of the flow varied from southwestward
to southward. Nine sets of glacial striae have been observed and
plotted upon the map. They are distributed as follows:

1 S 45° W, on the roadside 1%4 miles northeast of Lake Pleasant
village.

64 NEW soRK STATE MUSEUM

2 S 40° W, on the roadside 2 miles northeast of Lake Pleasant
village. |
3.5 45° W, on the roadside 1 mile south-southeast of Lake Pleasant

village.
4 S 40° W, on the roadside 11%4 miles southwest of Lake Pleasant
village.

5 40° W, on the roadside 124 miles west of Lake Pleasant village.

S 15° W, on the roadside 114 miles southeast of Speculator
village.

S 30° W, where the road crosses the summit of West hill south-
west of Wells village. This is the finest example of a glaciated
rock ledge noted in the whole quadrangle. An area of fully
one hundred square feet on the dark hornblende gneiss is
beautifully polished and groved.

8 S 15° W, about half way up the west face of Wallace mountain,
at many places on several vertical ledges — one of them 40 feet
high and 100 yards long — of Grenville light gneiss, the rock
wall is worn smooth and glossy and shows distinct glacial striae.

g N-S. In the field 1 mile northeast of Benson village. The prin-
cipal mark is a shallow grove 2 feet long.

In addition to these, a number of ledges just off the map and 1
mile due northwest of Speculator village are beautifully polished
and striated with striae bearing S 30° to 40° W. The small num-
ber of observed striae within the quadrangle as compared with the
large number recently located by the writer on the North Creek
sheet is largely due to more numerous traveled roads within the
latter region, because in working the roads Postglacially un-
weathered ledges are often uncovered. With the Lake Pleasant
quadrangle seven of the nine observations were made along the
roads. 7

In the northwestern portion of the quadrangle there was clearly
a strong southwesterly ice current perfectly parallel to the trend of
the main valleys and ridges. The ice in the valley at Wells moved
S 30° W across the tops of West hill and perfectly parallel to the
fault rift valley. Between Wallace and Three Ponds mountains,
the ice movement was parallel to the eastern side of Cathead moun-
tain ridge. Just how far the direction of ice movement was deter-
mined by the topography can not be said, though there can be no
doubt that the undercurrents at least were forced into almost per-
fect parallelism with the trend of the valleys.

During the time of maximum glaciation, however, the general
ice movement across the quadrangle must have been toward the

Or U1

a

|
|
4
4
|

GEOLOGY OF LAKE PLEASANT QUADRANGLE 65

southwest except in the southeastern portion where it was more
nearly southwest, thus harmonizing with the northern portion of
the Broadalbin quadrangle. It is also worthy of note that instead
of the strongly predominant southward ice movement across the
North Creek quadrangle we have here a predominating southwest-
ward movement. |

As regards depth of ice, the most significant striae are those on
Wallace mountain which lie at an altitude of from 2100 to 2200 feet
and, since the glaciation here was vigorous, there can be no doubt
but that the ice was deep enough to cover the mountain. The striae
on West hill are at 1360 feet so that, at the very lowest calculation,
the ice through the Wells valley was 500 feet deep. The other
striae are too near valley bottoms to be especially significant. The
presence of glacial boulders and lakes, however, on some of the
highest mountains of the quadrangle, together with the general con-
sideration of all northern New York, leaves no doubt but that the
great ice sheet completely buried the whole quadrangle.

No positive evidence for any important ice erosion was discovered
within the region. The throughly glaciated surfaces here described
do not necessarily imply deep cutting by the ice. In its passage
through the Wells valley the ice must have plucked off many large
blocks of the Cambric rocks as proved by the presence of so many
such blocks in the west Sacandaga valley in the vicinity of Black-
bridge. It is more than probable that the Sacandaga lake and Lake
Pleasant basins were scoured and somewhat deepened by the ero-
sion, but how much can not be said. At any rate, ice erosion was
sufficiently effective to scrape off practically all Preglacial soils
and decomposed rocks so that good examples of rotten rock in situ
are of very uncommon occurrence.

Ice deposits

Erratics. Glacial boulders or erratics are of course scattered
over all portions of the quadrangle, and as usual most of them are
within or not far to the south or southwest of the rock areas from
which they were derived. Where exposures are scarce, the great
predominance of a certain kind of rock among the boulders gives a
fair idea of the underlying rock mass. More or less angular
erratics, often several feet across, occur even on high mountains,
thus proving great depth of ice. The only noteworthy erratics ap-
parently derived from without the quadrangle are of typical gabbro
in the northwestern portion in the vicinity of the two large lakes.

66 NEW YORK STATE MUSEUM

These erratics are frequently seen; are usually fairly well rounded,
though hard and fresh; and they indicate the presence of consider-
able gabbro masses not far to the north or northeast of the lakes.
The only other erratics of special interest are those of Cambric
rocks in the vicinity of Blackbridge, which were derived from the
valley at Wells.

Till. As usual, within the Precambric rock area, typical boulder
clay is rarely met with here, the ground morainic material almost
always being very sandy or gravelly and generally filled with
boulders. Such material is of quite common occurrence in the val-
leys or along ‘stream channels. A good example may be seen a
mile north of Wells, just where the road enters the Elbow creek
gorge. About a mile farther along this same road other good de-
posits occur. All these consist mostly of heterogeneous mixture of
sand, loam and small to large, not very well rounded, boulders, with
sometimes suggestions of stratification. This narrow valley or
‘gorge lay at right angles to the direction of ice flow and hence was
very favorably situated for accumulation of ground morainic
materials.

Perhaps the most extensive deposits of till occur within a mile
of the river (West Branch) on the south side from Whitehouse
eastward for three miles. The best exposures may be seen where
Ninemile creek cuts through the till showing thickness up to 50
or even 100 feet. This valley also lay directly across the main ice
current and the conditions for accumulation of till were very favor-
able just after the passage of the ice over the high mountain masses
on the north side of the river.

Still other good exposures of till may be seen along the main
road which passes through Benson village. Many other less inter-
esting examples occur.

Kames. Good kame areas are seldom seen, though at two places
they are especially well developed. One of these is across the river
from Wells between the road and the base of the mountain
where many kames occur, some reaching heights of 50 to 75 feet.
The other good kame area lies along the valley bottom about a mile
south of Blackbridge. This is a large group of kame hills more
or less merged together and consisting wholly of irregularly strati-
fied sand and gravel with a maximum thickness of no less than 100
feet.

No prominent boulder moraines were noted by the writer.

GEOLOGY OF LAKE PLEASANT QUADRANGLE 67

Extinct glacial lakes and their deposits

Wells lake. There are several fine examples of extinct glacial
lakes within the quadrangle, all being here described for the first
time. One of these lakes occupied the bottom of the valley at Wells
as proved by a number of perfect delta deposits. The surface of
the lake stood at an altitude just a little over 1020 feet The
finest flat-topped delta terrace extends from about one-fourth to
three-fourths of a mile north of the north end of the village and
is well shown on the map. Occasionally a low mound of boulder
morainic material projects above the surface of the delta deposit.
Where the main road to Lake Pleasant crosses its southern end,
the delta material is seen to be stratified coarse gravel and sand, with
lower level minor terraces developed by Postglacial stream cutting.
The boulder-free delta terrace at many places comes sharply against
the heavy boulder morainic deposits. Continuing northward beyond
the terrace for fully a mile, water-laid gravel may be seen along
the river road.

A smaller though fine, flat-topped terrace of gravel one-half of a
mile long lies at 1020 feet just northeast of the mouth of Muill creek.

The northern portion of the village rests upon a good terrace con-
sisting mostly of sand with some gravel at 1020 feet. This is too
narrow to be shown on the map.

Another very distinct sand terrace one-fourth of a mile long
lies on the west side of the river at about one-fourth of a mile south
of the bridge at the lower end of the village. It is not shown on
the map.

This lake was formed by a blockade of glacial drift or ice across
the Sacandaga river channel somewhere within a mile south of
the lower end of the village. The only possible outlet of this lake
was over this drift or ice and the lake must have been short-lived,
due to a combination of rapid filling by delta deposits and rapid
downcutting through the dam. Much of the lake deposit has been
removed by the Sacandaga river since the existence of the lake.
The length of the lake was 3% miles with an average width of
from one-half to two-thirds of a mile. As would be expected,
the coarsest materials (largely gravels) are found in the northern
portion of the old lake bed, because the swift debris-laden ice there

1[t should of course be remembered that at the time of the existence of
this and other similar lakes of the quadrangle, the whole Adirondack region
stood several hundred feet lower than at present so that all lake levels were
correspondingly lower.

3

68 NEW YORK STATE MUSEUM

entered the lake. Except near the lower bridge, the river has no-
where cut through this old lake deposit to the underlying rock.

Whitehouse lake. This large lake occupied the valley of the
West Branch of the Sacandaga river from 2 miles west of White-
house to near the mouth of Jimmy creek. Its length was about
5% miles with general width of from one-half to 1 mile. A num-
ber of fine boulder-free sandflats or delta terraces. at concordant
altitudes proves the former existence of this body of water whose
surface corresponded to an altitude a little above the present 1380
foot line.

Along the trail three-fourths of a mile, and also 1% miles, north-
west of Whitehouse are excellent sand flats at an altitude of 1380
feet, the first named only being shown on the contour map. Along
the road for over 3 miles eastward from Whitehouse much lake
deposit material may be seen, the two best terraces being respec-
tively one-half of a mile north of the mouth of Ninemile creek
and 1 mile west of the mouth of Jimmy creek. At the first men-
tioned locality, the sand flat lies at 1380 feet with a low knob of
boulder morainic material rising above it. The terrace material
is stratified and fine gravel as shown in a road cut. At the second
named place, a fine big sand flat lies a little below 1380 feet.

This lake was formed by a blockade of glacial debris or ice across
‘tthe river channel in the vicinity of the mouth of Jimmy creek.
‘Since abundant, heavy, boulder morainic material still remains here
and also since the only possible outlet of the lake was eastward, the
dam was more likely one of drift than of ice.

Arietta lake. This long narrow lake occupied the valley bottom
of the West Branch Sacandaga river from the Shaker Place
(Piseco Lake sheet) and eastward past Avery’s Place and to the
mouth of Silver lake stream (Lake Pleasant sheet) with a branch
extending southward from Arietta over the areas of the three Stink
lakes (Lassellsville sheet). Excellent sand flats at 1680 feet along
the road a mile north of Arietta and from the mouth of North
Branch eastward for a mile, show the former water level.

Hope lake. This long, narrow lake occupied the Sacandaga
valley bottom from the mouth of the West Branch Sacandaga
river to or near Northville, a distance of 10 or 11 miles. An arm
of this lake probably extended up the valley of East Stony creek
to near Hope Falls. For a mile just below the mouth of West
Branch, the river road lies on a distinct sand flat at 940 feet. Near
the mouth of Colombe brook a small, though perfect, delta terrace of
gravel and sand lies at about 940 feet. Beginning 11% miles south

GEOLOGY OF LAKE PLEASANT QUADRANGLE 69

of the mouth of Colombe brook, a very perfect, narrow sandflat
at 940 feet extends three-fourths of a mile southward nearly to
Dewey creek. Just below this, and crossed by the road, is a stream-
cut terrace in the lake deposits at 920 feet. From here down the
river for 5 miles there is no distinct terrace above goo feet, but at
5% miles down, or one-half of a mile west of Hope valley (Stony
creek sheet) there is a fine large sand flat lying between 900 and
920 feet altitude, probably nearer 920 feet. This terrace quite
certainly correlates with the ones above mentioned, its somewhat
lower level being due to Postglacial warping of the land. A smaller
terrace at the same altitude lies one-half of a mile west of the mouth
of West Stony creek. Just north of the village of Northville there
is a fine delta terrace at 860 to 880 feet which Fairchild correlates
with his Amsterdam lake, but this terrace seems too low to be cor-
related with that already described farther up the river. Thus it
appears most likely that the Hope glacial lake was held by a dam
of drift or ice across the valley about 1 or 1% miles north of North-
ville where much drift. still obstructs the channel. A possible view,
however, is that Hope lake was only an arm of the low water stage
of Schoharie lake or a high water stage of Amsterdam lake as
described by Fairchild.’

Benson Center lake. This small lake occupied the valley bottom
at Benson Center, its old shore line closely corresponding to the
present 1300-foot contour line. The perfectly developed sand flats
at nearly 1300 feet represent the old lake deposits which have been
considerably removed by Postglacial erosion of the stream passing
through the valley. A dam of drift or ice across the stream chan-
nel from 1 to 2 miles south of the village held up the water.

Most of the areas now shown as swamps were formerly small
lakes but these do not merit special description.

Existing lakes

Sacandaga lake and Lake Pleasant. It is certain that these
lakes were formerly more extensive than at present, the old shore
lines having been some 15 to 20 feet higher. The best sand flats,
representing a portion of the lake deposit of the larger lakes, lie
one-fourth of a mile southeast of the village of Speculator at an
altitude of about 1740 feet. This higher Sacandaga lake sent a
small arm northwest to Mud lake, another to Echo lake, and also
covered all the swamp area just east of the present lake. The con-

1N. Y. State Mus. Bul. 160, p. 26-30.

7O NEW YORK STATE MUSEUM

necting arm between the two larger lakes was also shorter and
somewhat wider. The larger Lake Pleasant spread over most of
the swampy area just east and north of the present lake, and also
probably sent a long narrow arm northward to cover the area of
Elm lake. The former water level was, and the present one is, held
up by Pleistocene deposits east of Speculator.

Piseco lake. There is positive evidence that the water of Piseco
lake formerly stood fully 20 feet higher as shown by the perfectly
developed delta sand flats at an altitude of something over 1680
feet in the vicinity of Rudeston and Piseco at the south end of the
lake. During this higher water stage, a long arm extended north-
ward to include even Fawn lake. <A perfectly continuous swamp
(old lake) area reaches from Piseco to Fawn lake and the greater
elevation (1695 feet) of Fawn lake is readily explained as due to
the Postglacial differential elevation of the land increasing north-
ward at the rate of several feet a mile.

Oxbow and Hamilton lakes. These two lakes were certainly
a few feet higher formerly so that the water spread over the swamp
areas just northward in each case. The waters of these lakes are
held in by drift dams.

Other lakes. Several small lakes deserving special mention be-
cause of their remarkable situations on mountain side or top are:
Johnson Vly lake (altitude 1980 feet) 214 miles northeast of Guide
Board hill; Loomis pond (altitude 2240 feet) 1 mile north of North
Branch mountain; Buck pond (altitude 2550 feet) 1% miles
northeast of Whitehouse; and Three ponds (altitude 2480 to 2600
feet) on Three Ponds mountain. Perhaps the most remarkable is
Buck pond situated almost at the summit of a steep mountain which
rises over 1400 feet above the river level. All these small lakes
are of the usual glacial type with drift dams and afford positive
evidence for a depth of ice great enough to cover the mountains on
which they occur.

All other lakes of the quadrangle are likewise held up by drift
dams.

The gorge of West Branch

The gorge of the West Branch Sacandaga river is situated be-
tween 2 and 3 miles west of Whitehouse. For a half mile the
practically perpendicular rock walls of this narrow gorge rise from
200 to 300 feet. The river has just room enough at the bottom.
It seems certain that the river here flows in a Postglacial channel.
Such high, steep rock walls could scarcely have withstood the rav-

GEOLOGY OF LAKE PLEASANT QUADRANGLE 71

ages of weathering and frost action during the long Preglacial
period of erosion.

An examination of the topographic maps shows no possible Pre-
glacial channel of the West Branch Sacandaga river to the south,
west or north. Thus we are obliged to look for an eastward chan-
nel. Such a Preglacial channel is thought to be just north of The
Gorge. A small eastward flowing stream?! occupies a wide, deep
channel really much more commensurate with a large stream such
as the river. The narrowest part of the channel is just at the map
edge, but since it is there heavily drift filled, the Preglacial rock
channel was certainly wider and somewhat deeper. At this place
the altitude of the present stream is less than 1680 feet, while west-
southwestward at Mud lake and the Piseco outlet the altitude is
nearly 1660 feet. The low, intervening divide is clearly due to
drift accumulation and, by allowing for comparatively little depth
of drift, there is no difficulty in considering the Preglacial river
channel to have been here. The Gorge has been cut as a notch by
the Postglacial river where it entered by steep gradient into the
Preglacial valley.

STONE QUARRIES

In Precambric rocks

Grenville marble. Of the few small masses of Grenville crystal-
line limestone or marble within the quadrangle, the only one ever
commercially used lies 1% miles a little south of east of Lake Pleas-
ant village, where are located an old quarry and a limekiln. The
rock is a medium-grained, greenish-gray, serpentine marble with
occasional green patches or blotches of serpentine. Many years
ago some of the rock was burned in the kiln for the production of
quicklime, while some is said to have been quarried and shipped for
building and decorative purposes.

Road metal and building stone. During 1912 the only quarry
in the syenitic or granitic rocks was alongside the state road 14
miles northeast of Lake Pleasant village. This rock was crushed
for use in building the state road. Other quarries have doubtless
since been opened for state road work between Hope and Wells.

The best road material of the quadrangle is the diabase, which
is a fine quality of so-called “ trap-rock,” but the only one of these
dikes known to be really accessible for road work is the one east

1 This stream, instead of emptying into Hamilton Lake stream as shown
on the map, really enters the river nearly a mile above the mouth of Hamilton
Lake stream.

72 NEW YORK STATE MUSEUM

of Benson village. The best abundant rock, however, for macadam-
izing roads is the syenite, especially the basic varieties which are
hard and rich in iron-bearing minerals but which usually contain
little or no quartz or mica.

The syenites and granites would furnish durable and beautiful
building stones, but their distance from market has so far prevented
any considerable use of these rocks.

Feldspar and mica. Pegmatite dikes, which are so often pros-
pected and quarried for feldspar or mica, are comparatively scarce.
One prospect hole has been opened in pegmatite along the small
stream one-half of a mile east of the south end of the village of
Wells. Good muscovite mica and potash (orthoclase) feldspar
were found but neither in sufficient quantity to pay for mining.

In Paleozoic rocks

Little Falls dolomite. Many years ago, along the line of outcrop
of the Little Falls dolomite in the outlier near Hope, this rock was
quarried (see map) and burned in nearby limekilns, the remains of
which may still be seen. What the burned lime was used for could
not be learned, but it was probably put upon the soil, as it makes
a very poor quicklime for plaster or mortar.

A small quarry in the dolomite has also been opened on the hill-
side one-third of a mile east of Wells, this rock being used for
building purposes in the village.

Lowville limestone. Many years ago two small quarries were
opened in the Lowville limestone, one within the small area in the
outlier near Hope (see map) and the other along the small stream
three-fourths of a mile west of Wells. In both cases the rock was
burned in nearby limekilns (still standing) for the production of
quicklime, this rock being of very excellent quality for the purpose.

Trenton limestone. The Trenton limestone a mile north of the
north end of Wells village was quarried many years ago and burned
for quicklime in a kiln which still stands. This rock is of good
quality for the purpose, but no extensive operations were ever
carried on.

A very small quarry was also opened in the Trenton limestone
one-half of a mile west-northwest of Wells. This rock is the shaly
Trenton near the shale contact and was used for road work.

Canajoharie shale. The only quarry in this rock lies just above
the road across the river one-half of a mile west of the northern
part of Wells village. A considerable amount of the shale has been
taken out for road repair work in the Wells valley.

a, sa

INDEX

Abner brook fault, 54
Altitudes, 7-8

Alvord, gabbro, 28

Amsterdam limestone, 37
Anorthosite gabbro, 8, 13-14
Arietta lake, 68

Auger flats, granite porphyry, 26

Benson, 7; diabase, 31; mixed gneiss,
27

Benson Center, 7; Grenville series,
12; mixed gneiss, 27

Benson Center lake, 69

Black River limestone, 8, 37, 43

Blackbridge, gabbro, 29

Blue Ridge-Three Ponds mountain
fault, 54, 55

Buck pond, 70; syenite, 22

Buck pond ridge fault, 52, 56

Building stone, 71

Burnham mountain fault, 50

Calymmene senaria, 41

Cambro-Ordovicic, strata, concealed,
41

Canajoharie (Trenton) shale, 8, 33,
40, 72; at Wells, 45

Cathead mountain, 8; fault, 48;
mixed gneiss, 27; syenite, 15

Cenozoic history, 60

Charley lake fault, 49

Chub mountain fault, 53

Climacograptus putillus, 41

Colombe brook, Grenville series, 13;
mixed gneiss, 27; syenite, 15

Colombe brook-Cathead mountain
fault, 48

Cushine, t1.°P., cited, 11, 14, 17, 21,

37, 45

Dalmanella testudinaria, 39, 41

Darton, W. H.., cited, 9, 33

Devorse creek, fault, 46; granite, 26

Dewey creek, fault, 49; granite por-
phyry, 26

Diabase, 8, 30-31; examples of, 31

[73]

Diplograptus amplexicaulis, 41

Drainage, 61-63

Dunham mountain, Grenville series,
13

Dunning pond granite, 24

Echo lake, granite porphyry, 26;
Grenville series, 12

Elbow creek, fault, 50, 55; syenite,
15

Elbow mountain fault, 55; granite
porphyry, 26; Grenville series, 13

Elbow-Three Ponds mountain fault,
46

Emmons, E., cited, 9, 32, 41

Erratics, 65

Fault ridges and troughs, 55
Faults, 9, 45-57; Abner brook, 54;
Blue’ Ridge-Three Ponds moun-
fain, 54, 55; Buck Pond ridge, 52,
56; Elbow mountain, 55; Finch
mountain, 55; Fish mountain, 55;
Fish-Oxbow mountain, 50; Gil-
mantown, 50; Grant-Woods lake,
54; Groff-Little Cathead moun-
tain ridge, 56; Hamilton lake, 51;
Hope outlier, 48; Indian Head
mountain, 55, 56; joining of, 56;
Lake Pleasant, 50; Moose creek,
52, 53; Moose-North Branch
mountain, 56; Mount Dunham, 50,
55; Mount Orrey-Dunham ridge,
55; Mount Rouge, 55; Ninemile
creek, 53, 55; North Branch
Moose mountain, 53; Piseco lake,
51; Sacandaga lake, 50; Silver lake

outlet, 53; Speculator-Hamilton
mountain, 49; Speculator moun-
tain, 55; Speculator village, 51;

Sugar loaf-Silver lake mountain,
53; Swart mountain, 52; topo-
graphic influence and rock charac-
ter, 60; Wells outlier, 46; White-
house, 52, 53; Whitman mountain,

54

74 NEW YORK STATE MUSEUM

Fawn lake, drainage, 63
Feldspar; 72

|

Jackson seat syenite, 15
Jimmy creek fault, 49, 52

Fiddler's lake, fault, 51; syenite, 20 | Johnson Vly lake, 70

-Finch mountain, fault, 55; syenite, 19 |

Fish mountain, fault, 55; Grenville

series, I2; syenite, I5
Fish-Oxbow mountain fault, 50
Foliation, 32

Gabbro, 8, 28-30; examples of, 31

Gilman lake fault, 49, 50

Gilmantown, 7; fault, 50

Glacial boulders, 65

Glacial lakes, extinct, 67-69

Glaciology, 9, 63-71

Glossina trentonis, 41

Gneiss, Grenville series, 9-13; mixed,
26-27

Gorge of West Branch of Sacandaga
fiver, .70*, mMabase 37> fault sis
gabbro mass, 29; syenite, 20

Granite, 23-26

Granite and syenite porphyries, 25

Granitic syenite, 20

Grant-Woods lake fault, 54

Grenville marble quarries, 71

Grenville series, 9, 13, 54

Groff-Little Cathead mountain ridge
fault, 56

Groff mountain,
porphyry, 26

Guideboard hill, diabase, 30; Gren-
ville series, 12

fault, 48; syenite

Hamilton lake, 70; fault, 51

Hamilton lake stream granite, 24

Hamilton mountain, 8, 21, 47

Hatch brook fault, 48

Hatchery brook fault, 50

Helldevil dam fault, 53

Hill, B. F., cited, 0, 33

Hope, 8; outlier near, 41-43, 56; out-
lier faults, 48

Hope lake, 68

Hormotoma cf. gracilis, 39

Ice deposits, 65-66

Ice movement and erosion, 63-65
Illaenus sp., 39

Indian Head mountain fault, 55, 56
Isotelus, 39

Kames, 66

Kemp, J. F., cited, 9, 32, 33, 34, 38, 390
Kennyetto creek drainage, 61, 63
Kunjamuk valley fault, 51

Lake Pleasant (village), 7; Grenville
series, 12

Lake Pleasant, 69; fauit, 50, 51

Lake Pleasant region, white gneiss,
II

Lakes, existing, 69-70; extinct glacial
lakes, 67-69

Lattice drainage, 63

“Laurentian ” granite, II

Leperditia fabulites, 39

Leray member of the Lowville lime-
stone, 37 7

Limestone, II

Lingula curta, 41

Liospira cf. lenticularis, 39

Little Cathead mountain mixed
gneiss, 27

Little Falls dolomite, 33, 35-36, 41,
42, 44, 58, 72

Lookout mountain, Grenville series,
12

Loomis pond, 70; Grenville series, 10

Lowville limestone, 32, 37, 38, 72

Meco lake, 54; mixed gneiss, 27;
syenite, 20

Mesozoic history, 59

Mica, 72

Miller, W. J., cited, 9

Moose creek fault, 52, 53

Moose mountain fault,
gneiss, 27

Moose-North Branch mountain mass,
8; fault, 56

Mount Dunham, fault, 55; fault at
west base of, 50; mixed gneiss, 27;
syenite, 15

Mount Francisco syenite, 22

Mt Orrey, 47

Mount Orrey-Dunkam ridge fault,

55

53; mixed

INDEX TO GEOLOGY OF THE LAKE PLEASANT QUADRANGLE 75

Mt Rouge, 47; fault, 55
Mount Rouge-Dunham ridge, 8
Mud lake mountain fault, 52

Newland, D. H., cited, 9, 33

Ninemile creek, fault, 53, 55; gabbro,
29; granite, 25; syenite, 19; till, 66

North Branch-Moose mountain fault,
53

Northville Paleozoic area, 32

Notch, the, fault, 46; Grenville series,
10

Oak Hill fault, 50

Orthoceras hudsonicum, 41 cf. jun-
ceum, 39

Oxbow lake, 70

Oxbow mountain fault, 50

Pachydictya acuta, 39

Paleozoic history, 57-59; rock out-
liers, 8, 32-45

Panther mountain fault, 51

Pegmatite dikes, 72

Phytopsis tubulosum, 37

Pine lake fault, 53

Pine mountain fault, 53

Piseco lake, 7, 70; fault, 51

Plectambonites sericeus, 39, 41

Porphyries, granite and syenite, 25-
26

Potash mountain fault, 52

Potsdam sandstone, 8, 33, 34, 4I, 42,
44, 58

Precambric history, 57; rocks, 9-32

Primitiella unicornis, 41

Quartzites, 10

Refinesquina alternata, 39, 4I
deltoidea, 39

Rhynchotrema inequivalve, 39

Road metal, 71

Rock lake, 54

Ruedemann, R., cited, 9, 33, 37, 39

Sacandaga lake, 7, 69; drainage, 63;
fault, 50; Grenville series, 12

Sacandaga river, 7; drainage, 61;
fault, 53, 55; granite porphyry, 26;
mixed gneiss, 27

Sand lake, syenite, 17
Silver Lake mountain,
Grenville series, 10

Silver lake outlet fault, 53

Smyth, C. H., cited, 17

Southerland mountain fault, 48

Speculator-Hamilton mountain fault,
49

Speculator-Lookout mountain
syenite, 18

Speculator mountain, 8;
syenite, 17

Speculator village fault, 51

Stone quarries, 71-72

Streptelasma corniculum, 39

Sugarloaf-Silver Lake
fault, 53

Swart mountain fault, 52

Syenite, 14-23; basic phases, 17; ex-
amples of, 16; granitic, 20

Syenite-granite series, 8

Syenite porphyries, 25-26

fault, 53;

area,

fault 55%

mountain

Tetradium tubulosum, 43

Theresa transition beds, 8, 33, 35,
4I, 42, 44, 58

Three ponds, 70

Three Ponds-Blue Ridge mountain
mass, 8

Three Ponds mountain, fault, 54, 55;
Grenville series, Io

Till, 66 ;

Trenton limestone, 8, 33, 38, 72

Tribes Hill limestone, 36

Wallace mountain, Grenville series,
if)

Wells, 7, 8; Canajoharie black shale,
45; outlier at, 32; outlier faults, 46

Wells lake, 67

West branch Sacandaga river, dia-
base, 31; drainage, 61; gorge of,
70-71

West Hill, granite, 25; Grenville se-
ries, 13; mixed gneiss, 2

Whitehouse, fault, 52, 53; syenite, 23

Whitehouse lake, 68

Whitman mountain, fault, 54; gran-
ite porphyry, 26

Willis mountain fault, 52

The University of the State of New York
New York State Museum

JoHN M, CLarRKE, Director

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and 13th (1893) are omitted from the 45th and 47th museum reports.

Senarate volumes of the following only are available.

Report Price» Report Price Report Price
12 (1892) $.50 17 $.75 2I $.40
14 75 18 7 22 .40
ER aie. 2 19 .40 ? 23 Ay
16] [ 20 .50 \See Director’s annual reports

Paleontologist’s annual reports }1899—date.

See first note under Geologist’s annual reports.
Bound also with museum reports of which they forma part. Reports for 1899 and 1900
may be had for 20c each. Those for 1901-3 were issued as bulletins. In 1g904 combined

with the Director’s report.
Entomologist’s annual reports on the injurious and other insects of the
State of New York 1882-date.

“Reports 3-20 bound also with museum reports 40-46, 48-58 of which they forma part,
Since 1898 these reports have been issued as bulletins. Reports 3-4, 17 are out of print,
other reports with prices are:

Report Price Report Price Report Price
I $.50 II $.25 21 (Bul. 104) $.25
2 -30 I2 .25 22 ( * IIo) .25
5 .25 13 Out of print 23° ("1 124) seer
6 «25 14 (Bul. 23) .20 24CP vite A).) oes
7 .20 Dei 31) «55 25 ( 2s) T4An)e as
8 way a i ily 36) .25 260:(* par) 235
9 .25 r8'(“ 64)..20 27(* 155) '.40
10 «35 TOIG* 76) .35 28 ( “* 165) 40

THE UNIVERSITY OF THE STATE OF NEW YORK

Reports 2, 8-12 may also be obtained bound in cloth at 2s5c each in addition to the pricé®
given above.

Botanist’s annual reports 1867-date.

Bound also with museum reports 21-date of which they form a part; the first Botanist’s
report appeared in the 21st museum report and is numbered 21. Reports 21-24, 29, 31-41
were not published separately.

Separate reports for 1871-74, 1876, 1888-98 are out of print. Report for 1899 may be had
for 20c; 1900 for soc. Since ryor these reports have been issued as bulletins.

Descriptions and illustrations of edible, poisonous and unwholesome fungi of New York
nave also been published in volumes 1 and 3 of the 48th (1894) museum report and in volume
1 of the 49th (1895), srst (1897), 52d (1898), 54th (1900), 55th (1901), in volume 4 of the
56th (1902), in volume 2 of the 57th (1903), in volume 4 of the 58th (1904), in volume 2
of the soth (1905), in volume xr of the 6oth (1906), in volume 2 of the 61st (1907), 62d
(1908), 63d (1909), 64th (1910), 65th (1911) reports. The descriptions and illustrations of
edible and unwholesome species contained in the 49th, s1st and 52d reports have been re-
ae and rearranged, and, combined with othe1s more recently prepared, constitute Museum

emoir 4.

Museum bulletins 1887—-date. 8vo. To advance subscribers, $2 a year, or $1
a year jor division (1) geology, economic geology, paleontology, mineralogy;
50¢ each for division (2) general zoology, archeology, miscellaneous, (3) botany ,
(4) entomology.

Bulletins are grouped in the list on the following pages according to divisions.
The divisions to which bulletins belong are as follows:

1 Zoology 62 Miscellaneous 123 Economic Geology

2 Botany 63 Geology 124 Entomology

3 Economic Geology 64 Entomology 125 Archeology

4 Mineralogy 65 Paleontology 126 Geology

5 Entomology 66 Miscellaneous 127 as

6 i. 67 Botany 128 ~

7 Economic Geology 68 Entomology 129 Entomology

8 Botany 69 Paleontology 130 Zoology

9 Zoology 70 Mineralogy 131 Botany

Ig Economic Geology 71 Zoology 132 Economic Geology

Ey ce 72 Entomology 134 Director’s report for £908
To ‘ 73 Archeology 134 Entomology

Tz Entomology 74 Entomology 135 Geology

I, Geology 75 Botany 136 Entomology

Is Economic Geology 76 Entomology 137 Geology

16 Archeology 77 Geology 138 "a

Iz Economic Geology 78 Archeology 139 Botany

T8 Archeology - ° ”9 Entomology 140 Director’s report for 1909
Tg Geology 80 Paleontology I41 Bes Ouiclony

29 Entomology 81 Geology 142 Economic Geology

2t Geology 82 “ 143 bs

22 Archeology 83 ce 144 Archeology

23 Entomology 84 4 145 Geology

24 ie 85 Economic Geology 146 Z

25 Botany 86 Entomology 147 Entomology

26 Entomology 87 Archeology 148 Geology —

aa A 88 Zoology 149 Director’s report for I910
28 Botany 89 Archeology 150 Botany

29 Zoology 90 Paleontology I51 Economic Geology
30 Economic Geoogy 91 Zoology 152 Geology
31 Entomology 92 Paleontology 153 ry
32 Archeology 93 Economic Geology 154 s
33 Zoology 94 Botany 155 Entomology
34 Geology 95 Geology 156 ze

35 Economic Geology 96 “ 157 Botany

36 Entomology 97 Entomology 158 Director’s report for 1911
37 r 98 Mineralogy 159 Geology
38 Zoology 99 Paleontology LOD) et nat
39 Paleontology too Economic Geology 161 Economic Geology
40 Zoology ror Paleontology 162 Geology

41 Archeology 102 Economic Geology 163 Archeology

42 Geology 103 Entomology 164 Director’s report for 1912
43 Zoology 104 a 165 Entomology

44 Economic Geology 105 Botany 166 Economic Geology

45 Paleontology 4 106 Geology 167 Botany

46 Entomology 107 Geology and Paleontuvlogy 168 Geology

47 $ 108 Arc’eology TAQ) 0%

48 Geology 109 Entomology ar [3 aie ea

49 Paleoatology IIo We 171 a

50 Archeology tr1 Geology sy oe ei

51 Zoology 112 Economic Geology 173 Director’s report for I913
52 Paleontology 113 Archeology 174 Economic Geolcgy

53 Entomology 114 Geology 175 Entomology

54 Botany 115 Geology 176 Botany

55 Archeology 116 Botany 177 Director’s report for 1914
56 Geology 117 Archeology 178 Economic Geology

57 Entomology 118 Geology 179 Botany

58 Mineralogy 119 Economic Geology 180 Entomology

59 Entomology 120 ts 181 Economic Geology

60 Zoology 121 Director’s report for 1907 182 Geology

61 Economic Geology 122 Botany

MUSEUM PUBLICATIONS

Bulletins are also found with the annual reports of the museum as follows:

Bulletin Report Bulletin Report Bulletin Report Bulletin Report :
12-15 48, Vv. 1 79 S9..Va ty Dt 2 rr9=—azr O61) V.r 154 64, V. 2
16,17 50, Vs.% 80 Seavert. Dor i raz 61, Vv. 2 155 65, Vv. 2
18,19 eye VT 81,82 Reyer 123 Or Var 156 Gn woe
20-25 yg 83,84 Se. iE 124 61, Vv. 2 157 O5; v.2
26-31 Ae: 85 58, Vv. 2 125 62, Vv. 3 158 OSV. i
32-34 BAL VW. Y 80 ROy Vas 126-28 62,Vv.1 I59 65 .°vCcr
35,36 54, Vv. 2 87-89 58,v.4 129 62, Vv. 2 160 OS srverr
37-44 a ae: 90 58, v. 3 130 62; V. 3 161 65, Vv. 2
45-48 RaW A gI Roe ved TAD raa iOagaveed 162 OSs. 'z
49-54 hy ae 92 ES, v. a 133 62,Vv.1 163 66, v. 2
55 Bon Ve 4 93 58, v. 2 134 62, Vv. 2 164 66, v. I
6 56,8. I 94 58, Vv. 4 135 63). Var 165-67 66, v. 2
57 56, v.3 95,96 58, v. 1 136 63, V.2 168-70 66, v. I
58 BGs Wy 2 97 EOvv. Ss 137 Os0Vi. Lr
5960 5G.-¥. 3 98,99 59, V. 2 138 One. Memoir
6l 56,v.1 100 BO, Vek 139 63) Vina 2 49, V. 3
62 56, Vv. 4 IOI 59, V.'2 140 63, V.1 344 535 ¥. 2
63 56, v. 2 102 50, (v.12 I4I Oa.ve2 5,0 57, V.3
64 56, V. 3 103-5 59,V.2 142 Gainve 2 7 Sv. 4
6) BOo Vig 106 EO, V..r 143 63; Vv. 2 SY Dtt BO.) Va3
6067 56, Vv. 4 107 60, V. 2 144 64, V. 2 8, pt 2 59, V. 4
68 56, Vv. 3 108 60, V. 3 145 04; Viz 9, ptr 60, Vv. 4
69 56, Vv. 2 109,110 60, Vv. 1 146 Ode Vert 9, pt 2 62) 'V./4
70.71 Beane Doi rwx 60, Vv. 2 147 G4), V2 Io 60, Vv. 5
72 Be eee Dt Bs TES GOnv. I 148 64, Vv. 2 II OF Vis
73 &57,Vv.2 113 60, Vv. 3 149 OAMVed E22, Derr 63, V.3
74 See L, Dba TIA 60, V. I I50 64, Vv. 2 T25ipt 2 66, v. 3
75 57,V.2 IIs 60, V. 2 I51 64, Vv. 2 13 OR ervera
7° SU. Mek, Dt 2 .rr6 60, Vv. 1 152 64, Vv. 2 TA Wonk OS; vars
77 Bis ar Dee Ey 60, Vv. 3 153 64, Vv. 2 TAi ve 2 Ie.
8 BP Vert 118 60, Vv. I

The figures at the beginning cf :ach entry in the following list indicate its number as a
museum bulletin.

Geology and Paleontology. 14 Kemp, J. F. Geology of Moriah and West-
port Townships, Essex Co., N. Y., with notes on the iron mines. 38p.
iovgp. 2 maps. sept. 1895. Free.

19 Merrill, F. J. H. Guide to the Study of the Geological Collections of
the New York State Museum. 164p. 1r19pl. map. Nov. 1898. Out of print.

21 Kemp, J. F. Geology of the Lake Placid Region. 24p. 1pl. map. Sept.
1898. Free.

34 Cumings, E. R. Lower Silurian System of Eastern Montgomery County;
Prosser, C. S. Notes on the Stratigraphy of Mohawk Valley and Sara-
toga County, N. Y. 74p. 14pl. map. May 1goo. 15c.

39 Clarke, J. M.; Simpson, G. B. & Loomis, F. R. Paleontologic Papers 1.
qg2p. il. r6pl. Oct. 1900. 15¢.

Contents: Clarke, J. M. A Remarkable Occurrence of Orthoceras in the Oneonta Beds of
the Chenango Valley, N. Y.

—— Paropsonema cryptophya; a Peculiar Echinoderm from the Intumescens-zone
(Portage Beds) of Western New York.

—— Dictyonine Hexactinellid Sponges from the Upver 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. 1116p. 2pl. map. Apr. I90T. 25¢c.

45 Grabau, A. W. Geology and Paleontology of Niagara Falls and Vicinity.
286p. il. 18pl. map. Apr. 1901. 65c; cloth, goc.

48 Woodworth, J. B. Pleistocene Geology of Nassau County and Borough
of Queens. 58p. il. 8pl. map. Dec. I901. 25c.

49 Ruedemann, Rudolf; Clarke, 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 durine the Devonic of
New York, Ireland and the Rhineland.

52 Clarke, J. M. Report of the State Pzleontologist rg01. 280p. il. ropl.
map, 1 tab. July 1902. 4oc.

THE UNIVERSITY OF THE STATE OF NEW YORK

56 Merrill, F. J. H. Description of the State Geologic Map of 1901. 42p.
2 maps, tab. Nov. rgo2. Free.

63 Clarke, J. M. & Luther, D. D. Stratigraphy of Cananadigua and Naples
Quadrangles. 78p. map. June 1904. 25c.

65 Clarke J. M. Catalogue of Type Specimens of Faleozoic Fossils in the
New York State Museum. 848p. May 1903. $1.20 cloth.

69 Report of the State Paleontologist 1902. 464p.52pl.7 maps. Nov.
1903. $1, cloth.

77 Cushing, H. P. Geology of the Vicinity of Little Falls, Herkimer Co.
g8p. il. “Tspl. 2 maps. Jan. 1905. 30C

80 Clarke, J. M. Report of the State Paleontologist 1903. 396p. 2gpl.
2 maps. Feb. 1905. §85c, cloth.

81 Clarke, J. M. & ee D. D. Watkins and Elmira Quadrangles. 32p.
map. Mar. 1905. 25

82 Geologic Map oF the Tully Quadrangle. 4op.map. Apr.1905. 20¢c.

83 Woodw orth, J. B. Pleistocene Geology of the Mooers Quadrangle. 62p.
25pl. map. June 1905. 25¢c

Ancient Water Lev els of the Champlain and Hudson Valleys. 206p.
il. rrpl. 18 maps. July 1905. 45¢c.

90 Ruedemann, Rudolf. Cephalopod: of Beekmantown and Chazy For-
mations of Champlain Basin. 224p. il. 38pl. May 1906. 75¢, cloth.

92 Grabau, A. W. Guide to the Geology and Paleontology of the Schoharie
Region. 314p.il. 26pl. map. Apr. 1906. 75¢c, cloth.

95 Cushing, H. P. Geology of aes Northern Adirondack Region. T88p.
15pl. 3 maps. Sept. 1905. 30

96 Ogilvie, I. H. ee of the Dados Lake Quadrangle. 54p il. r7pl.
map. Dec. 1905. 30c

99 Luther, D. D. Geology of the Buffalo Quadrangle. 32p. map. May
1906. 20C.

tee. Geology of the Penn Yan-Hammondsport Quadrangles. 28p.
map. July 1906. Out of print.

106 Fairchild, H L. Glacial Waters in the Erie Basin. 88p. 1r4pl 9 maps.
Feb. :907. Out of print.

107 Woodworth, J. B.; Hartnagel, C. A.;. Whitlock, H. P.; Hudson, G. H.;
Clarke, J. M.; White. David & Berkey. C. P. Geological Papers. 388p.
54pl. map. May 1907. go, cloth.

Contents: Woodworth, J. B. Postglacial Faults of Eastern New York.
Hartnagel, C. A. Stratigraphic Relations of the Oneida Cong!omerate.

Upper Siluric and Lower Devonic Formations of the Skunnemunk Mountair Region.

Whitlock, H. P. Minerals from Lyon Mountain, Clinton Co.

Hudson, G. H. On Some Pelmatozoa from the Chazy Limestone of New York.

Clarke, 2 M. Some New Devecnic 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. Str ctural and Stratigraphic Features of the Basal Gneisses of the High-
lands.

84

111 Fairchild, H. L. Drumlins of New York. 6op. 28pl. 19- maps. July
1907. Out of print

114 Hartnagel, C. A. Geologic Map of the Rochester and Ontario Beach
Quadrangles. 36p. map: Aug. 1907. 20C.

115 Cushing, H. P. Geology of the Long Lake Quadrangle. 88p. 2opl

map. Sept. Koo7-. (25¢:

118 Clarke, J. M. & Luther, D. D. Geologic Maps and Descriptions of the
Portage and Nunda Quadrangles including a map of Letchworth Park
5op. r6pl. 4 Maps. Jan. 1908. -.:35c¢-

126 Miller, W. J. Geology of the Remsen Quadrangle. 54p. il. rrpl. map.
jan. 1999. . 25e

127 Fairchild, H. L. Glacial Waters in Central New York. 64p. 27pl. 15
maps. Mar. 1g09. Out of print. :

128 Luther, D. cs Geology of the Geneva-Ovid Quadrangles. 44p. map
Apr. 190

135 Miller, WoT. i: “Geology of the Port Leyden Quadrangle, Lewis County,
N. Y. 62p. il. ripl. map. Jan. rg10. 25¢.

MUSEUM PUBLICATIONS

137 Luther, D. D. Geology of the Auburn-Genoa Quadrangles. 36p. map.
Mar. 1910. 20C.

138 Kemp, J. F. & Ruedomant; Rudolf. Geology of the Elizabethtown
and Port Henry Quadrangles. 176p. il. 2opl. 3 maps. Apr. 1910. Not
available.

145 Cushing, H. P.; Fairchild, H. L.; Ruedemann, Rudolf & Smyth, C. H.
Geology of the Thousand Islands Region. 1g4p. il. 62pl.6 maps. Dec.
1910. $1.00 cloth.

146 Berkey, C. P. Geologic Features and Problems of the New York City
(Catskill) AaRedsct: 286p. il. 38pl. maps. Feb. 1911. 75c; cloth, $1.

148 Gordon, E. Geology of the Poughkeepsie Quadrangle. 122p. il.
26pl. map. ier LOTT. . Zac,

152 Luther, D. D. Geology of the Honeoye-Wayland Quadrangles. 3op.
mee. Bet. 1911. 20e:

153 Miller, William J. Geology of the Broadalbin Quadrangle, Fulton-
Saratoga Counties, New York. 66p. il. S8pl. map. Dec. 1911. 25¢.

154 Stoller, James H. Glacial Geology of the Schenectady Quadrangle. 44p.
gp map, Dec r9grt. 206.

159 Kemp, James F. The Mineral Springs of Saratoga. 8op. il. 3pl. Apr.
ners.” 15cC,

160 Fairchild, H. L. Glacial Waters in the Black and Mohawk Valleys. 48p.
il. 8pl. 14 maps. May 1912. 50c.

162 Ruedemann, Rudolf. The Lower Siluric Shales of the Mohawk Valley.
152p. il. r5pl. Aug. 1912. 35c.

168 Miller, William J. Geological History of New York State. 130p.. 43pl.
Io maps. Dec. 1913. 40c.

169 Cushing, H. P. & Ruedemann, Rudolf. Geology of Saratoga Springs and
Vicinity. 178p. il. 20 pl. map. Feb. IQI4. 40c.

170 Ss gear William J. Geology of the North Creek Quadrangle. gop. il. 14pl.

I9I4. 25¢.

Es Hopkins, T. C. The Geology of the Syracuse Quadrangle. 8op. il. 2opl.
map. July 1914. 25c.

172 Luther, D. D. Geology of the Attica and Depew Quadrangles. 32p. map.
August I914. 15c.

182 Miller, William J. The Geology of the Lake Pleasant Quadrangle. 76 p.
il. 1op] map. Feb. 1916. 25c.

Stoller, James H. Glacial Geology of the Saratoga Quadrangle. In press.

Miller, William J. Geology of the Blue Mountain Quadrangle. Prepared.

Martin, James C. & Chadwick, George H. Geology of the Canton Quad-
rangle. In press.

Luther, D.D. Geology of the Phelps Quadrangle. In preparation.

Whitnall, H. O. Geology of the Morrisville Quadrangle. Prepared.

Hudson, G. H. Geology of Valcour Island. Jn preparation.

Economic Geology. 3 Smock, J. C. Building Stone in the State of New
York. 1354p. 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.

Building Stone in New York. 210p. map, tab. Sept. 1890. Nol
available.

Ir Merrill, F. J. H. Salt and Gypsum Industries of New York. og 4p. 12pl.
2 maps, 11 tab. Apr. 1893. Not available.

12 Ries, Heinrich. Clay Industriesof New York. 174p.il. 1pl.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. s5z2p. ra4pl.
2 maps. Oct. 1897. I5¢.

30 Orton, Edward. Petroleum and Natural Gas in New York. 1236p. il.
3 maps. Nov. 1899. _ 165c.

35 Ries, Heinrich. Clays of New York; their Properties and Uses. 456p.
140pl. map. June 1900. Out of print.

Lime and Cement Industries of New York; Eckel, E. C. Chapters

on the Cement Industry. 332p. rorpl. 2 maps. Dec. 1901. 85c. cioth

Io

17

THE UNIVERSITY OF THE STATE OF NEW YORK

1 Dickinson, H. T. Quarries of Bluestone and Other Sandstones in New
York. 1r14p. 18pl. 2 maps. Mar. 1903. 35¢c.

85 Rafter, G. W. Hydrology of New York State. gop. il. 44pl. 5 maps.
May 7905. $1.50, cloth.

93 Newland, D. H. Mining and Quarry Industry of New York. 78p.
July t905. Out of prent.

too McCourt, W. E. Fire Tests of Some New York Building Stones. 4op.
26pl. Feb. 1906. 15€¢c.

102 Newland, D. H. Mining and Quarry Industry of New York 1905
162p. June 1906. 25¢c.

112 Mining and Quarry Industry of New York 1906. 82p. July
1907. Ont of print.

II9 & Kemp, J. F. Geology of the Adirondack Magnetic Iron Ores
with a Report on the Mineville-Port Henry Mine Group. 184p. rapl.
8 maps. Apr. 1908. 35¢c.

120 Newland, D.H. Mining and Quarry Industry of New York 1907. - 8ap.
July 1908. 15¢c.

123 & Hartnagel, C. A. Iron Ores of the Clinton Formation in New
York State. 76p. il. r4pl.3 maps. Nov. 1908. 25¢c.

132 Newland, D.H. Mining and Quarry Industry of New York 1908. 98p.
July 1909. 15¢c.

1 2 —— Mining and Quarry Industry of New York for1gog. g8p. Aug.
1910. Not available.

143 Gypsum Deposits of New York. 94p. zopl. 4maps. Oct..1g10 35¢.

151 —— Mining and Quarry Industry of New York 1g1o. 82p. June IgII. I5c.

161 Mining and Quarry Industry of New York tg11. 114p. July 1912. 20c.
166 Mining and Quarry Industry of New York 1912. 114p. August 1913.
20¢.
L74 Mining and Quarry Industry of New York 1913. 111 p. Dec. 1914.
20¢.
-178 Mining and Quarry Industry of New York 1914. 88p. Nov. 1915. 15c.
181 The Quarry Materials of New York. 212p. 34 pl. Jan. 1916. 4oc.

Mineralogy. 4 Nason,F.L. Some New York Minerals and Their Localities.
22p. ipl. Aug. 1888. Free.

58 Whitlock, H. P. Guide to the Mineralogic Collections of the New York

State Museum. 1rs5op. il. popl. 11 models. Sept. 1902. 4oc.

New York Mineral Localities. trop. Oct. 1903. 200.

Contributions from the Mineralogic Laboratory. 38p. 7pl. Dec.
1905. Out of print.

Zoology. 1 Marshall, W. B. Preliminary List of New York Unionidae.
zop. Mar. 1892. Not avatlable.

9 Beaks of Unionidae Inhabiting the Vicinity of Albany, N. Y. j3op.
ipl. Aug. 1890. Free.

29 Miller, G. S., jr. Preliminary List of New York Mammals. 124p. Oct.
1899. I5¢C.

33 ea M.S. Check List of New York Birds. 224p. Apr. 1go0. 25¢c.

38 Miller, G. S., jr. Key to the Land Mammals of Northeastern North
America.- 106p. Oct. rg00. I5¢.

40 Simpson, G. B. Anatomy and Physiology of Polygyra albolabris and
Limax maximus and Embryology of Limax maximus. 82p. 28pl. Oct.
IQ0I. 25¢.

43 Kellogg. J. L. Clam and Scallop Industries of New York. 36p. 2pl.
map. Apr. 1gor. Free.

51 Eckel, E. C. & Paulmier, F.C. Catalogue of Reptiles and Batrachians
of New York. 64p.il. rpl. Apr. 1902. Out of print.

Eckel, E. C. Serpents of Northeastern United States.
Paulmier, F.C. Lizards, Tortoises and Batrachians of New York.

60 Bean, T. H. Catalogue of the Fishes of New York. 784p. Feb. 1903.
$1. cloth.

70
98

MUSEUM PUBLICATIONS

71 Hellogs. J. L. Feeding Habits and Growth of Venus mercenaria. 3op.
4 Sept. 1903. Free.

88 oat Elizabeth J. Check List of the Mollusca of New York. 116p.
May 1905. 20¢.

gI ei F. C. Higher Crustacea of New York City. 78p. il. June

maa.

ae *Shufeldt, R. W. Osteology of Birds. 382p. il. 26pl. May 1909. 50c.

Entomology. 5 Lintner, J. A. White Grub of the May Beetle. 34p. i
Nov. 1888. Free.

6 Cut-worms. 38p. il. Nov. 1888. Free.

13 San José Scale and Some Destructive Insects of New York State,
54p. 7pl. Apr. 1895. 15¢.

20 Felt, E. P. Elm Leaf Beetle in New York State. 46p. il. spl. June

1898. Free.

See 57.

14th Report of the State Entomologist 1898. 1sop. il. gpl. Dec.
1898. 20¢.

Memorial of the Life and Entomologic Work of J. A. Lintner Ph.D.
State Entomologist 1874-98; Index to Entomologist’s Reports 1-13. 316p,
fuk. Oct. 1899: 35¢.

Supplement to 14th report of the State Entomologist.

26 Collection, Preservation and Distribution of New York Insects
36p. il. Apr. 1899. Out of print.

27 Shade Tree Pests in New York State. 26p. il. spl. May 1899.
Free.

31 15th Report of the State Entomologist 1899. 128p. June r1goo.
I5c

36 16th Report of the State Entomologist 1900. 118p. 16pl. Mar,

IQOI. 25¢.

: Catalogue of Some of the More Important Injurious and Beneficial

Insects of New York State. 54p. il. Sept. 1900. Free.

Scale Insects of Importance and a List of the Species in New York
Stite. 1940. er 5pl. . June igor.’ 25¢.

47 Needham, J. G. & Betten, Cornelius. Aquatic Insects in the Adiron-
dacks. 234p. il. 36pl. Sept. roor. 45¢c.

53 Felt, E. P. 17th Report of the State Entomologist r901. 232p. il. 6pl.
Aug. 1902. Out of print.

Elm Leaf Beetle in New York State. 46p. il. 8pl. Aug. 1902.

Out of print.

This is a revision of Bulletin 20 containing the more essential facts observed since that
was prepared.

37
46

57

59 Grapevine Root Worm. 4op. 6pl. Dec. 1902. Not available.
See 72.
64 18th Report of the State Entomologist 1902. s110p. 6pl. May

1903. 206.
68 LS sepeereainy J. G. & others. Aquatic Insects in New York. 322p. 52pl.
Aug. ene 80c, cloth.
72 Felt, FP; Grapevine Root Worm. 58p. 13pl. Nov. 1903. 20¢.

This is a revision of Bulletin 59 containing the more essential facts observed since that
was prepared.

74 & Joutel, L. H. Monograph of the Genus Saperda. 88p. r4pl’
June ee 25c.

76 Felt, eth Report of the State Entomologist 1903. 1r50p. 4pl.
1904. IS5C.

79 Mosquitos or Culicidae of New York. 1064p. il. 57pl. tab. Oct.

1904. 40C.

86 ecahan, J. G. & others. May Flies and Midges of New York. 352p.
il. 37pl. June 1905. Out of print.

97 Felt, E. P. 20th Report of the State Entomologist 1904. 246p. il. rgpl.
Nov. 1905. 4o0¢.

103 Gipsy and Brown Tail Moths. 44p. ropl. July 1906. I15¢.

THE UNIVERSITY OF THE STATE OF NEW YORK

104 21st Report of the State Entomologist 1905. 1344p. 10opl. Aug.
1906. 25C.

109 Tussock Moth and Elm Leaf Beetle. 34p. 8pl. Mar. 1907. 200.

IIo 22d Report of the State Entomologist 1906. 1152p. 3pl. June
r907.)' 256.

124 23d Report of the State Entomologist 1907. 542p. il. 44pl. Oct.
THOS: -F5C.

I29 Control of Household Insects. 48p.il. May 1909. Out of print.

134 24th ogee of the State Entomologist 1908. 208p. il. 17pl.
Sept. 1909. 35¢

136 Control of Flies and Other Household Insects.. 56p. il. Feb.
Lota.) z5c:

This is a revision of Bulletin r2q containing the more essential facts observed since

that was prepared.

141 Felt, E. P. 25th Report of the State Entomologist 1909. 178p. il. 22pl.

July 1910. Not available.
147 26th Report of the State Entomologist rg10. 182p. il) 35pl. Mar.
yee ton. 2th Report of the State Entomologist 1911. 3198p. il. 27pl. Jan.
Ps gia Bim Leaf Beetle and White-Marked Tussock Moth. 35p. 8pl. Jan.
ee 38th Report of the State Entomologist 1912. 266p. 14pl. July 1913.
ree 29th Report of the State Entomologist 1913. 258 p. 16 pl. April
180 oth Report of the oe Entomologist 1914. 336p. il. 19 pl. Jan.
Cc

Needham, J. G. Monograph on Stone Flies.

Botany. 2 Peck, C. H. Contributions to the Botany of the State of New
York. 72p. 2pl. May 1887. 20c.

8 Boleti of the United States. 98p. Sept. 1889. Out of print.

25 Report of the State Botanist 1898. 76p. spl. Oct. 1899. Out of .
print.

28 Plants of North Elba. 206p. map. June 1899. 2oC¢.

54 —— Report of the State Botanist 1901. 58p. 7pl. Nov. 1902. 4oc.

67 —— Report of the State Botanist 1902. 1096p. 5pl. May 1903. Soc.

75 —— Report of the State Botanist 1903. 7op. 4pl. 1904. 4oc.

94 —— Report of the State Botanist 1904. 6o0p.1opl. July 1905. 4o0¢.

105 —— Report of the State Botanist 1905. 108p.12pl. Aug.1906. 5o0c.

116 —— Report of the State Botanist 1906. 1120p. 6pl. July 1907. 35¢c.

122 —— Report of the State Botanist 1907. 178p. spl. Aug. 1908. 4o0c.

131 —— Report of the State Botanist 1908. 202p. 4pl. July 1909. 4oc.

139 —— Report of the State Botanist 1909. 1316p. 10opl. Mayigio. 45c.

150 —— Report of the State Botanist 1910. 1oop. spl. May r1g1r. 3oc.

157 —— Report of the State Botanist 1911. 1140p. opl. Mar. 1912. 35¢c.

167 —— Report of the State Botanist 1912. 138p. 4pl. Sept. 1913. . 30c.

176 —— Report of the State Botanist 1913. 78p. 17pl. June 1915. 20c.

179 —— Report of the State Botanist 1914. 1108p. tIpl. Dec. 1915. 20c.

Archeology. 16 Beauchamp, W. M. Aboriginal Chipped Stone Implements

of New York. 86p.

18 Polished Stone Articles Used by the New York Aborigines. I04p.
45pln row, 18672) 25e.

22 Earthenware of the New York Aborigines. 78p. 33pl. Oct. 1898.
25.

32 Aboriginal Occupation of New York. i1g90p. 16pl. 2 maps. Mar.
Ig00. 30C.

41 Wampum and Shell Articles Used by New York Indians. 166p.
28pl. Mar. 1901. Out of print.

50 Horn and Bone Implements of the New York Indians. 112p. 43p!.
Mar. 1902, Out of print.

ezpl... Qet. 1897: -

In preparation.

Not available.

MUSEUM PUBLICATIONS

Metallic Implements of the New York Indians. 94p. 38pl. June
Ig02. 25¢.

Metallic Ornaments of the New York Indians. 122p. 37pl. Dec.
1903. Not available.

55
73

78 History of the New York Iroquois. 340p. 17pl. map. Feb. 1905.
75¢.

87 Perch Lake Mounds. 84p.12pl. Apr. 1905. 200.

89 Aboriginal Use of Wood in New York. gop. 35pl. June 1905.

Not available.

108 Aboriginal Place Names of New York. 336p. May 1907. 40c.

II3 Civil, Religious and Mourning Councils and Ceremonies of Adop-
tion, 1158p. 7pl. June 1907. 25¢.

117 Parker, A. C. An Erie Indian Village and Burial Site. 1oz2p. 38pl.
Dec. 1907. 30C.

125 Converse, H. M. & Parker, A.C. Iroquois Myths and Legends. rg6p.
il. rrpl. Dec. 1908. 5oc.

144 Parker, A. C. Iroquois Uses of Maize and Other Food Plants. 1120p.
il. 3rpl. Nov. 1910. Not available.

163 The Code of Handsome Lake. 144p. 23pl. Nov. 1912. Not available.

— The Constitution of the Five Nations. In press.

Miscellaneous. 62 Merrill, F. J. H. Directory of Natural History Museums
in United States and Canada. 236p. Apr. 1903. 30¢.

66 Ellis, Mary. Index to Publications of the New York State Natural
History Survey and New York State Museum 1837-1902. 418p. June
¥903. 75c, cloth.

Museum memoirs 1889-date. 4to.

1 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. 7opl.
1898. $2, cloth.

3 Clarke, J. M. The Oriskany Fauna of Becraft Mountain, Columbia Co.,
no ee rop. opt.» Oct. .r900.: Soc.

4 Peck, C. H. N. Y. Edible Fungi, 1895-99. 106p. 25pl. Nov. 1900. Not
available.

This includes revised descriptions and illustrations of fungi reported in the 49th, 51st and
52d reports of the State Botanist.

5 Clarke, J. M. & Ruedemann, Rudolf. Guelph Formation and Fauna of
New York State. 196p. 21pl. July 1903. $1.50, cloth.

6 Clarke, J. M. Naples Fauna in Western New York. 268p. 26pl. map.
1904. $2, cloth.

7 Ruedemann, Rudolf. Graptolites of New York. Pt 1 Graptolites of the

' Lower Beds. 350p. 17pl. Feb. 1905. $1.50, cloth.

8 Felt, E. P. Insects Affecting Park and Woodland Trees. v.1. 46op.
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 1. 366p. il. 7opl.5 maps. Mar. 1908. $2.50, cloth; Pt 2. 250p. il. 36pl.
4 maps. Sept. 1909. $2, cloth.

1o Eastman, C. R. The Devonic Fishes of the New York Formations.
a36p. r5pl. 1007. $1.25, cloth.

tr Ruedemann, Rudolf. Graptolites of New York. Pt 2 Graptolites of
the Higher Beds. 584p. il. 3rpl. 2 tab. Apr. 1908. $2.50, cloth.

12 Eaton, E. H. Birds of New York. v. 1. 5orp. il. 42pl. Apr. roro.
$3, cloth; v. 2, 719p.il. 64 pl. July 1914. $4, cloth.

13 Whitlock,H.P. Calcitesof New York. trgop. il.27pl. Oct. rg10. $1, cloth.

14 Clarke, J. M. & Ruedemann, Rudolf. The Eurypterida of New York. v. I.
Text. 440p. il. v.2 Plates. 188p. 88pl. Dec. 1912. $4, cloth.

Natural History of New York. 3o0v. il. pl.maps. 4to. Albany 1842-94.

DIVISION 1 zooLOoGy. 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 oj print,
Historical introduction to the series by Gov. W. H. Seward. 178p.

THE UNIVERSITY OF THE STATE OF NEW YORK

v. 1 ptr Mammalia. 131 + 46p. 33pl. 1842.

300 copies with hand-colored plates,

v. 2 pt2 Birds. 12+ :380p. r4rpl. 1844.
Colored plates.

v. 3 pt3 Reptiles and Amphibia. 7+ 98p. pt4 Fishes. 15 + 415p. 1842.
pt 3-4 bound together.

v. 4 Plates to accompany v. 3. Reptiles and Amphibia. 23pl. Fishes.
7yopl. 1842.

300 copies with hand-colored plates. !

v. 5 pts Mollusca. 4 +271p. gopl. pt6 Crustacea. jop.13pl. 1843-44.
Hand-colored plates; pts—6 bound together.

DIVISION 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. 2v. il. pl. sq. 4to. Albany 1843. Out of print.

v. 1 Flora of the State of New York. 12+ 484p. 72pl. 1843.

300 copies with hand-colored plates.

v. 2 Flora of the State of New York. 572p. 89pl. 1843.
300 copies with hand-colored plates.

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.

v. 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. 4to. Albany
1842-43. Out of print.

v. ptr Mather, W. W. First Geological District. 37 + 653p.46pl. 1843.

v. 2 pte Emmons, Ebenezer. Second Geological District. I0 + 437p.
Ey pl. “ode,

v. 3 pt3 Vanuxem, Lardner. Third Geological District. 306p. 1842.

v 4 pt4 Hall, James. Fourth Geological District. 22 + 6383p. rgpl.
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. 1 Soils of the State, Their Composition and Distribution. 11 + 371p. 2rpl.
1846. ¥

v. 2 Analysis of Soils, Plants, Cereals, etc. 8 + 3434+ 46p. 42pl. 1849.
With hand-colored plates.

v.,3 Fruits, etc. 8 + 340p. 1851.

v. 4 Plates to accompany v. 3. g5pl. 1851.

Hand-colored.

v. 5 Insects Injurious to Agriculture. 8+ 272p. 5opl. 1854.
With hand-colored plates.

DIVISION 6 PALEONTOLOGY. Hall, James. Paleontology of New York. 8v.
il. pl. sq. 4to. Albany 1847-94. Bound in cloth.

v. 1 Organic Remains of the Lower Division of the New York System.
23 + 338p. ogopl. 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 Oriskany
Sandstone. pti, text. 12 + 532p. 1859. [$3.50}

pt 2. 142pl. 1861. [$2.50]

MUSEUM PUBLICATIONS

v. 4 Fossil Brachiopoda of the Upper Helderberg, Hamilton, Portage and
Chemung Groups. 11 +1+ 428p.69pl. 1867. $2.50.

v. 5 pt x Lamellibranchiata 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+ 293p. 51pl. 1885. $2.50.

pt 2 Gasteropoda, Pteropoda and Cephalopoda of the Upper Helder-
berg, Hamilton, Portage and Chemung Groups. 2v. 1879. v. 1, text.

15 + 492p.; v.2. r20pl. $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 Catskill

Groups. 64 + 236p.46pl. 1888. Cont. supplement tov.5,pt2. Ptero-

poda, Cephalopoda and Annelida. 42p. 18pl. 1888. $2.50.

& Clarke, John M. v.8ptz1 Introduction to the Study of the Genera

of the Paleozoic Brachiopoda. 16 + 367p. 44pl. 1892. $2.50.

& Clarke, John M. v. 8 pt 2 Paleozoic Prachiopoda. 16 + 394p. 64pl.
1894. $2.50.

Catalogue of the Cabinet of Natural History of the State of New York and
of the Historical and Antiquarian Collection annexed thereto. 242p. 8vo.
1853. Out of print.

Handbooks 1893-date.

New York State Museum. s52p. il. 1902. Free.

! *Outlines, history and work of the museum with list of staff 1902.

Paleontology. 12p. 1899. Out of print.

Brief outline of State Museum work in paleontology under heads: Definition; Relation to
bology; Relation to stratigraphy; History of paleontology in New York.

Guide to Excursions in the Fossiliferous Rocks of New York. 124p. 1899.
Free.

Itineraries of 32 trips covering nearly the entire series of Paleozoic rocks, prepared specially
for the use of teachers and students desiring tc acquaint themselves more intimately with the
classic rocks of this State.

Entomology. 15p. 1899. Out of print.

Economic Geology. 44p. 1904. Free.

Insecticides and Fungicides. 20p. 1909. Free.

Classification of New York Series of Geologic Formations. 32p. 1903. Out
of print. Revised edition. 96p. 1912. 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 Museum
Report, v.1. 59x67 cm. 1894. Scale 14 miles to 1 inch. 165c.

Map of the State of New York Showing the Location of Quarries of

Stone Used for Building and Road Metal. 1897. Out of print.

Map of the State of New York Showing the Distribution of the Rocks

Most Useful for Road Metal. 1897. Out of print.

Geologic Map of New York. tg01. Scale 5 milesto1inch. Jn atlas
form $2. Lower Hudson sheet 6oc.

The lower Hudson sheet, geologically colored, comprises Rockland, Orange, Dutchess,
Putnam, Westchester, New York, Richmond, Kings, Queeris and Nassau counties, and parts

of Sullivan, Ulster and Suffolk counties; also northeastern New Ttersey and part of western
Connecticut.

Map of New York Showing the Surface Configuration and Water Sheds
tgo1. Scale 12 milesto 1inch. 15c.

- —— Map of the State of New York Showing the Location of Its Economic
Deposits. 1904. Scale 12 miles to 1 inch. 15c.

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. 1898. Out of print.

Area around Lake Placid. 1898.

Wieinity of Frankfort Hill [parts of Herkimer and Oneida counties]. 1899.

THE UNIVERSITY OF THE STATE OF NEW YORK

Rockland county. 1899.

Amsterdam quadrangle. 1900.

*Parts of Albany and Rensselaer counties. ryor. Out of print.
*Niagara river. IgoI. 25C.

Part of Clinton county. trgor.

Oyster Bay and Hempstead quadrangles on Long Island. rgor.
Portions of Clinton and Essex counties. 1902.

Part of town of Northumberland, Saratoga co. 1903.

Union Springs, Cayuga county and vicinity. 1903.

*Olean quadrangle. 1903. Free.

*Becraft Mt with 2 sheets of sections. (Scale 1 in. = } m.) ; 1903.

*Canandaigua-Naples quadrangles. 1904. 20¢.
*Little Falls quadrangle. 1905. Free.
*Watkins-Elmira quadrangles. 1g05. 20¢.
*Tully quadrangle. 1905. Free.

*Salamanca quadrangle. 1905. Free.

*Mooers quadrangle. 1905. Free.

Paradox Lake quadrangle. 1905.

*Buffalo quadrangle. 1906. Free.

*Penn Yan-Hammondsport quadrangles. 1906. 20¢.
*Rochester and Ontario Beach quadrangles. 2oc.
*Long Lake quadrangle. Free.
*Nunda-Portage quadrangles. 2oc.

*Remsen quadrangle. 1908. Free.
*Geneva-Ovid quadrangles. 1909. 200.

*Port Leyden quadrangle. s1g1o. Free.
*Auburn-Genoa quadrangles. 1910. 20¢.
*Elizabethtown and Port Henry quadrangles. I910. I5¢.
*Alexandria Bay quadrangle. i1g10. Free.
*Cape Vincent quadrangle. 1910. Free.
*Clayton quadrangle. Igio. Free.
*Grindstone quadrangle. Igio. Free.
*Theresa quadrangle. Igio. Free.
*Poughkeepsie quadrangle. Igir. Free.
*Honeoye-Wayland quadrangle. I9gII. 20¢.
*Broadalbin quadrangle. 1911. Free.
*Schenectady quadrangle. 1911. Free.
*Saratoga-Schuylerville quadrangles. 1914. 20c.
*North Creek quadrangle. 1914. Free.
*Syracuse quadrangle. 1914. Free.
*Attica-Depew quadrangles. I9g14. 20c.

*Lake Pleasant quadrangle. 1916. Free.

20c.

>

“ ete as
== - S<t<
4 ; ee, Deere ahaa, A

i

) JUBSBIT 2

UNIVERSITY OF THE STA’
JOHN M. CLARKE ‘TE OF NEW YORK

O STATE MUSE BULLETIN 182
STATE GEOLOGIST Ss USEUM LAKE PLEASANT QUADRANGLE

Canaj

ORDOVICIC

PALEOZOIG ROCKS

PRL 5 / Wea 6724702 ; ea oharie (Trenton)
; PLO SAN : é : i = black shale
= : s i ie oy! + “e
SJCANDA Es : iF E a eer) 2 maatiod
= 4 3 . 5 is ; foe pei y tales 2 ze Lower Trenton (Glens
s 3 = Z 3 Falls) and Black River
4 ‘ eo a 3 i : ‘ (Lowville) limestones
Little Falls dolomite
Theresa sandstone and
dolomite
Potsdam sandstone
Oambro-Ordovicic
strata (concenled)

IGNEOUS ROCKS

LATE SERIES

Diabase dikes

Gabbro stocks or
dikes
G@neizsoid bul younger than the
syenite and granite,
Granite and syenite
porphyries
Very porphyritic phases of
great syenife- granii
body.
Granite

A very quartease phase of the
ay ieays biotitic but non

EARLY SERIES

Granitic phase of
syenite
Intermediate deliocen normal
ayenile and granile and grad-

ing into both.

Basic phase of syenite

Usually non-quartzose and of
dioritie or gabbroie composition.

PRECAMBRIC ROCKS

Normal syenite
Gneissoid, somewhat quartzose,
augitic or hornblendic, and
younger than the Grenville.

is
Anorthosite gabbro

Regarded as older than the syentla

but younger than the Grenville.

MIXED ROCKS

Grenville-syenite-gran-
ite mixed gneisses
Grenville clorely involved with
syenite or granite,

MIXED SERIES

quartzite and some
crystalline limestone
Usually clearly banded

GRENVILLE SERIES

Dip and strike of foliation

Faults

/
J

Glacial striae

R
Stone quarries

x
Grenville limestone outcrops

AA and BB are the lines
of the structure sections
shown in figures 1 and 2.

vir 1908 BY USD. ®

, HM Wilson, Geographer Geology Bava! Miller,
JH. Jennings,in change of section \ i 191
Topography by Glenn. S. Smith, J.R Eakin
and New York State Land Survey
Assistants, A. Meade, jc OC Mernil.and Fred Graff Jr

SE See poe eae Raa Contour interval 20 feet

Datum is mean waa lever.
SURVEYED I COOPERATION WITH THE STATE OF NEW YOR:

SMITHSONIAN INSTITUTION LIBRARIES

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