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GEOLOGY OF FRANKLIN COUNTY _ 17
at least 1000 feet must be added to that amount and likely even
more. But at the time of their deposition the available evidence
indicates that the relief of the region was not as pronounced as
at present. The basal Potsdam is found running up to an ele-
vation of 1750 feet in the northern Adirondacks. With the relief
of the region as it is now the deposition of the minimum thickness
of the paleozoic rocks assigned above on this Potsdam would
jeave none of the present peaks projecting above the general
jevel.
Present character. At present the Adirondack region is consti-
tuted of ridge-like hills separated by valleys with usually a north-
east and southwest trend. The hills are sometimes clustered into
groups separated from one another by narrow passes, but these
very rugged tracts are exceptional. More commonly the valley
areas are considerable, and they often expand into quite wide
parks. The hills rise to very varying altitudes but present
always a general increase in hight going toward Mt Marcy and its
neighboring peaks. The valley bottoms show the same increase
in altitude in the same direction, though the amount of increase
. Ys less in their case, so that the hills tower higher above the
valleys as Marcy is approached. The valleys are clogged with
drift, in part morainic, in part deposited by overloaded glacial
streams, and in part deposited in the beds of former lakes (see
pl. 1). Were the drift cleared away, they would no longer be flat
bottomed as at present but have an irregular, hummocky surface,
as shown by the occasional protrusion of low ledges of rock above
the drift, by the very uneven rock surface shown along those
streams which have cut considerable valleys in the drift and by
the rock-bound character of the shores of some of the lakes which ~
still occupy valleys.
The hills are in general subdued in outline, instead of being
steep and jagged. They show in the majority of cases low, gentle
slopes to the north or northeast and steeper slopes to the south,
often marked by a cliff at the top. These features are in large
part due to glacial action. The low, northerly slopes appear to
have been much evened off by the ice sheet, are covered by a
TS NEW YORK STATE MUSEUM
mantle of drift and show very infrequent rock outcrops. As the
ice movement was to the southwest, the back slopes were, how-
ever, largely protected from wear. The cliffs are sometimes
around the sides of coves produced by the action of local glaciers
high up on the mountain sides and called cirques. At other times
they are independent of such features, but in either cage their —
origin seems referable to the same cause, namely that the glacier
did not closely hug the mountain side, but that a gap (bergschrund}
existed between the two, in which considerable range of daily
temperature with alternate freezing and thawing would occur and
produce rapid scaling off of the surface rock, the process being
made much more efficacious by the almost universal jointing of
the rocks. These joints have commonly a close approach to
verticality, and the scaling off of the rocks along them gives rise —
to perpendicular cliffs.
By no means all the cliffs of the region have this origin however-
Many steep-sided hills are found, where it seems strongly probable
that the steep face is a fault scarp, though usually it is not pos-
sible to demonstrate the truth of this view.
The outer Adirondack hills on the north are mainly cornea a
of red, orthoclase gneisses of unknown age and origin. These
hills usually show typically the low, even north slope and some-
what steeper back slope (see pl. 2). These rocks are folded, and
the folds pitch to the northward, sometimes only slightly, at others.
considerably. With this variation seems to come a variation in ©
the steepness of the north slope of the hills, though ordinarily
this is difficult of demonstration (pl. 3).
The anorthosite hills have usually steeper and somewhat more
rugged outlines than have those of gneiss, though this is not ne-
cessarily the case. Undoubtedly the lack of foliation in these rocks.
has some influence in the matter.
Old base levels of erosion. The Adirondack region has been con-
tinuously above sea level since Lower Silurian times, an interval
which represents a very considerable part of geologic time. Dur-
ing all these ages it has been subjected to unceasing wear, result-
ing in slow decrease in hight. The elapsed time has been suffi-
Reka
2S TER
SSTUND ODMINVUD
1O GHSOdNWOO AMV HOIHM STTIH GHG FO WdOTS MOVE UTAATTLS AGNV WdOIS HLUON
NOAG ‘MOT WHEL DNIMOHS !LSVG@ DNIMOO'T ‘ASV AVDOVALVHO UAddaN “ENIOd NVIGN] WOUd “ITI MOUs
6 948d ens
=
GEOLOGY OF FRANKLIN COUNTY (9
ciently long to permit the complete wearing down of the region,
not only once but more likely a half-dozen times from an elevation
such as the present one to the condition of a plain only moderately
elevated above sea level. But the opposite to this process has
also been in operation, and periods of quiet, during which the
surface has suffered steady decrease in elevation through erosion,
have alternated with intervals during which slow movements of
the earth’s crust have served to reelevate it. Where such inter-
vals of quiet are sufficiently protracted the surface may be wholly
worn down to a comparatively level plain known as a peneplain.
Above its fairly level surface low, rounded hills composed of the
more durable rocks may rise and are known as monadnocks.! If,
after erosion has produced this result, the region undergoes uplift,
the streams will commence to carve valleys in the elevated plain,
and, by the deepening and widening of these valleys with the
lapse of time, the old plain is carved into a hilly region, whose
valley bottoms are at a new base level. The former low relief
of the surface is indicated by the nearly uniform altitude to which
_ the hill tops rise, so that the observer has merely to imagine the
valleys refilled with the material which the streams have removed
to obtain a clear mental picture of the surface as it was before the
uplifting took place.
Two old base levels and two periods of uplift are clearly indi-
cated in the northern Adirondacks, even without the aid of good
~ maps and in spite of the difficulty of getting good views from most
of the hills, due to the heavily-forested character of the country.
One of the base levels is represented by the uneven line of the
hilltops, excluding however many of the higher summits; and the
other by the valley levels. The first period of uplift lowered the
base level from the hill summits to the valley bottoms, and the
second has produced a new base down toward which the streams
are actively cutting but which they have not yet reached.
In the northern Adirondacks the hills rise to such diverse alti-
tudes that the precise horizon of the old base which they repre-
sent has not been made out. The same difficulty is met when the
- 1Named from Mt Monadnock in New Hampshire, the type of the class.
80 NEW YORK STATH MUSEUM
new maps of Essex county are studied. These seem to show the
possibility of separating the hills into two classes several hundred
feet apart in altitude, but the distinction is not sharp, and all
sorts of intermediate elevations occur. It is quite certain that, —
when this erosion period was terminated by an uplift, the uplifted
surface was a quite hilly one, though it was also a surface of
moderate slopes and subdued relief.
The valley bottoms owe their present level character to glacial -
deposits. Their present quite uniform altitudes indicate strongly
a corresponding rather uniform altitude for the rock surface
buried beneath the drift. Many of the valleys ‘have resulted from
the erosion of the crystalline limestones and associated gneisses,
which are much the least resistant of all the Adirondack rocks.
Other valleys occupy lines of fracture or faulting. Still others,
however, are carved out of the same resistant rocks which consti-
tute the hills.
The period of time during which the region rested at the new
base was far less prolonged than the earlier period of rest. Some
of the valleys are quite wide, others are narrow, but as a general
average considerably less than half of the region has been cut
down to the new level.
The last period of uplift occurred in comparatively recent times
and must have been of considerable amount in order to give the
valleys their present elevation above tide.
Tilting of base levels. Throughout most of St Lawrence county
the hills are low, only rising a few hundred feet above the valleys,
and their summits rise to approximately the same altitudes.
Passing eastward into and across Franklin county, the hilltops,
though of variable hight, reach progressively greater and greater
elevations, till a north and south line is reached whose course
coincides approximately with the boundary line between Frank-
lin and Clinton counties and the prolongation of this line south-
ward. Along this line are situated the highest elevations in the
Adirondack region, culminating in the high peaks of the Marcy
group, of which Marcy and McIntyre exceed 5000 feet, and several
others nearly reach that elevation. To the north of these is
‘
SSIHND AHL AO HOLId UALVAUD AHL JO DNONOOOV NO TTIH
HoOUlg JO ASVO HHL NI NVHL YHAdHHLS AYV SHdOTIS HLOG “STIIH AHL WO @dOTS HiINOS
UAdAaLS HHL SHLVUISOTIT, “ISaM DNIMOOT UMINDO ANVNG WO HLOOS WMIIN T WOU NIVINDOW FOVNE YA
-
§ 481d
GEOLOGY OF FRANKLIN COUNTY 81
Whiteface, 4872 feet, only overtopped by four or five of the Marcy
peaks. Farther north is Lyon mountain, 3809 feet, the highest
points in Clinton county, though on the very outskirts of the hills.
Still farther north, beyond the outer hills, the basal beds of the
Potsdam sandstone constituting the edge of the high plain are
found, resting against the gneisses at the greatest altitude reached
by this plain north of the Adirondacks, and the gneisses have
their greatest extension to the northward along the same line.
Passing still farther east, beyond this line, there is a tolerably
rapid, often step-like, drop down to the level of Lake Champlain.
This descent is produced by a series of meridional faults with
down throw to the east, and the Champlain valley is a fault valley.
There is also faulting to the west of the main axis of elevation but
of a much less pronounced character, with the result that the
descent in this direction is much more gradual.
In addition to this main north and south axis of elevation,
there is also a minor east and west axis, the intersection of the
two being in the Marcy neighborhood. The highest summits in
Franklin county, Seward, Ampersand, Morris and Stony Creek
Pond mountains, lie along this axis to the west of Marcy. To the —
eastward the drop is rapid, but high peaks occur in Elizabethtown
along this line. The present configuration of.the northern Adiron-
dacks is then primarily due to dome-shaped uplifting, the Marcy
group of peaks denoting the point of maximum uplift.
The Adirondack region is one of considerable elevation, and
‘erosion goes forward quite rapidly, notwithstanding the heavy
forest covering and the resistant character of most of the rocks.
So pronounced an axis of elevation must be of comparatively
recent formation, otherwise it could not possibly be so plainly
marked a topographic feature. The prominence of many of the
fault scarps is impressive evidence in the same direction; for the
‘effect of long continued erosion is to wear away the raised block
-on the one side of the fault down the level of the dropped block
on the other. Apparently the recent elevation of the region has
been most largely effected by means of movements along the
‘fault lines.
82 NEW YORK STATE MUSEUM,
Both of the uplifts of the region which have been mentioned
were of the same nature, being greatest in the Marcy vicinity and
diminishing thence in all directions. This is shown by the fact
that the two base levels are separated by greater and greater
vertical distances in going toward Marcy from any direction.
Unfortunately definite figures are lacking, but in general the
valley bottoms range from 1500 to 2000 feet in altitude in the
heart of the Adirondacks and are 1000 feet lower than that over
a large part of St Lawrence county. The hills are only a few
hundred feet above the valleys in that county, whereas they range
from 1000 to 1500 feet above in Franklin county, leaving the
higher summits entirely out of the question. |
The Potsdam sandstone furnishes a good measure of the
amount of warping which the periphery of the Adirondack region
has undergone about the north and south axis since that rock was
deposited. On that axis the basal bed reaches an altitude of
about 1400’ A. T. (the still higher Potsdam is found in depressions
running back into the hills, and is not here considered). Going
toward Lake Champlain, faults drop it down below the level of —
the lake, 101’ A. T., within a very short distance. Along Lake
Champlain it lies mostly far below sea level, rocks many hundreds
of feet higher in the scale being at the surface. Going westward ©
across Franklin county and into St Lawrence, the altitude falls —
more slowly and steadily, so that in the neighborhood of Pots-
dam, about 50 miles distant, these beds lie from 600 to 800 feet
lower than at their highest point. These figures represent the
total amount of warping along this line since the deposition of —
the paleozoic rocks, subject to an unknown correction depending
on the variations in altitude of the floor on which the deposition
took place. That this floor was irregular is certain, that is, it
consisted of low ridges and valleys, but these are mere locak
irregularities. That this surface was canted at this time there is
no evidence. ,
1It must be borne in mind that only the northern Adirondacks are under
consideration. For a long distance to the southwest from Marcy the
valley levels drop little, if any.
GEOLOGY OF FRANKLIN COUNTY 83.
Drainage |
‘Lakes. Though lakes are of frequent occurrence throughout the-
Adirondack region, there is a belt of territory in southern Frank-
lin and northern Hamilton counties in which they are far more
numerous than elsewhere. In Franklin county they can be
enumerated by the hundred, and range from fairly large bodies of
water, several miles long, down to the most insignificant of ponds.
Very few data are available concerning them, and they would
well repay the careful study which could not be given them in a
hurried trip through the district during which the attention was.
centered qn other problems.
The lakes are massed in greatest number along the watershed
of the main streams, and do not differ greatly in altitude. This.
watershed is produced by the highest altitudes reached by the
drift in the old valley bottoms and is to a certain degree independ- ~
ent of the main axis of the hills. The belt of abundant lakes at
the head waters of the streams is due to the high level damsformed.
by rock ledges, whieh lie across their courses farther down. The
outlets of the lakes are in new channels and have encountered
ledges of rock through which they must cut. Thus the level of
Upper Saranac lake is maintained by the ledge of anorthosite over
which its outlet pours at the Bartlett club house; Lower Saranac
lake is held up by the ledges south of the village; Big Tupper lake
has its outflow directly into the Raquette, and the level of that
' gtream is determined by the rock ridge at Piercefield.
| The larger lakes have rock-bound shores for the most part, and
occupy the full width of the valley in which they lie. The lesser-
lakes may or may not have rocky shores, according as they lie in
narrow or wide valleys, or whether the hollow in which they
nestle lies in the center or toward the side of the valley.
The origins of these lakes are as various as the causes which
produce irregularities in the drift surface. The larger lakes
occupy portions of old stream valleys, which they fill from side to
side, and are held in place usually by morainic dams across the
valley. Some of the smaller lakes occupy kettle-holes in the...
84 NEW YORK STATE MUSHUM
moraines; some occur in hollows in the surface produced by the
‘uneven deposition of sand deltas by the overloaded streams of the
period of withdrawal of the ice; others are due to the damming
‘back of a valley’s drainage by such sands across the valley; yet
‘others may be due to other causes.
There is yet no evidence that any of them occupy rock basins,
though it is by no means impossible that such may be the case.
Big Tupper and Lower Saranac lakes may prove to belong to
this category. ;
Streams. During the withdrawal of the Laurentide glacier from
the northern Adirondacks, the preglacial stream courses cut in
tthe valley base level were completely filled by the glacial deposits,
‘while at the same time the irregular floor of the valley base itself
was covered and evened by them. After the departure of the ice
the courses of the streams were determined by the slope of these
deposits, this slope being in large measure independent of the
former channels, so that between the present and former courses
there is considerable discrepancy. - The slopes of the glacial de-
posits in the valleys were gentle, lakes occupied the hollows much
more numerously than at present, and the new streams obtained
steep grades only after they emerged from the hills on the slopes
leading down to the Champlain or St Lawrence valleys. Their
profile was convex, rather than concave, and so it remains to a
large extent today, while in mature stream valleys the profile is
concave.
The main streams of the region are of quite respectable size,
and their fall is great. The Saranac river from Lower Saranac
lake to Lake Champlain, in a course of about 75 miles by the river,
has a fall of 1450 feet, or 20 feet to the mile. The Ausable from
Lake Placid down, has a greater fall than the Saranac by 300 feet
‘in a course from 5 to 10 miles shorter. The Racquette and St Regis
rivers have a slope slightly less steep than that of the Saranac,
‘but only slightly. These are very considerable slopes for streams
-of such size, and excavation of their beds is going on at a quite
‘rapid rate. At first their courses were wholly in the unconsoli-
«dated drift deposits. These were quickly cut into, and soon the
GEOLOGY OF FRANKLIN COUNTY 8b
tops of the rock ridges of the valley floors, which lay underneath
the course of the stream where it was not over its old channel,.
were uncovered. The rapid down-cutting would be at once
checked at these points, and the laborious process of sawing
through the ridge substituted. But on the down stream side of
the ridge the cutting in the drift would continue active, thereby
producing a marked change in level at such points and causing
a fall or rapid down the slope of the ridge. The eventual hight
of this fall would mainly depend on the difference in altitude be-
tween the summit of the ridge and the summit of the next suc-
ceeding ridge uncovered by the stream below. By means of the
slow cutting back of the fall a gorge would be formed below,
which would correspond in depth with the hight of the fall. At
the High falls of the Saranac in Clinton county, for example.
the impressiveness of the fall and gorge are due to the fact that
the next rock encountered by the river, at Cadyville 10 miles dis-
tant, is at an altitude 450 feet lower.
Up stream from a rock obstruction the drift could not be cut
out to a greater depth than: the level of the obstruction, except
perhaps locally at the base of a fall. It would, however, be
quickly worn out down to that level. By this process the stream
-courses would be divided into sections of slight declivity and of
sluggish water, commencing and terminating at rapids over rock
ridges. As soon as this stage has been reached, the rate at which
erosion can go on becomes wholly dependent on the rapidity with
which the stream can saw through the hard rock obstructions.
‘All the principal streams of the northern Adirondacks illustrate
these general principles. Their headwaters are in chains of lakes,
and their courses below consist of reaches of “stillwaters” or
“levels ”, usually distinguished from one another locally by their
lengths, as the 16 mile level, the 8 mile level and so on, which
commence at the gorge below one rapid and terminate at the
brink of the next. The divides between two lakes belonging to
two different drainage systems are often of the most trivial char-
acter. Upper St Regis lake is less than a mile distant from Lake
Clear, which belongs to the Saranac system, and the divide be-
S86 “NEW YORK STATE MUSEUM
tween the two is low and composed wholly of drift. Indian carry,
‘between Upper Saranac lake and Stony creek pond belonging to
the Racquette system, is less than a mile long, with a probable
‘drift-filled channel between the two.
If the small brooks which cascade down the mountain sides into
the lakes are left out of account, the main streams all have greater
fall in their middle and lower reaches than in the upper portion :
of their courses. As time passes, this will become less and less
true, and when the drainage becomes mature the reverse will be
the case. When this stage is reached, the opportunities for whole-
sale changes in the present arrangement of the streams are sure
to be improved.
The four principal north-flowing rivers of the Adirondacks, the
Saranac, Ausable, Racquette and St Regis, rise in the heart of the
region and flow, the first two northeastward into Lake Cham-
plain, the others to the northwest into the St Lawrence, down the
slopes of the north-south axis of uplift. As they thus diverge,
_ ther streams take their rise on the opposite sides of the divide
to the northward, but their sources are at lower altitudes, and
they are of less volume and are shorter than the first four. The
‘Great Chazy, flowing northeast, and the Chateaugay, Salmon and
Deer rivers to the northwest are the principal members of this
group. :
The Saranac is unique among these streams in that it crosses
the main axis of elevation. Two main gaps cross this divide
north of Mt Whiteface. The first is to the eastward of Franklin
Falls, is due to the presence of the easily erodable rocks of the
crystalline limestone series, and is now drift-filled and not occu-
pied by any large stream, though seemingly the former channel
of one. The other gap, through which the Saranac now goes, is
at Unionfalls and has rock bottom in the river at 1400 feet, while
the altitude of the low divide on the drift surface in the valley
east of Franklin Falls is at 1700 feet.
The Saranac rises in Lake Clear, or rather in the large marsh
some two miles in diameter, which lies to the northeast of that —
body of water and is merely its former extension in that direction,
J
“4.> J
aa a
See Feo,
GEOLOGY OF FRANKLIN COUNTY 87
now completely shallowed and filled by vegetable matter. It
passes thence into Upper Saranac lake, Round lake and Lower
Saranac lake and leaves the latter near the middle of its eastern
gide in a wholly post-glacial channel. At the rapids at Saranac
village the river is only 6 miles distant from Lake Clear in an air
line, while by water it is from 25 to 30 miles distant. Below the
village the first considerable rapid is at Franklin Falls some 20
miles away, where the river falls 40 feet within the space of half
a mile. In the 20 miles above it has falien less than 100 feet, or
only about 4 feet a mile. Below the falls it flows through a gorge
half a mile long, with walls 100 feet high, which apparently
marks the channel of a small preglacial stream, or else a low
divide between two small streams. Below the gorge a wide
marshy valley opens out, through which the river flows in a
beautiful series of meanders. Heavy drift-filling turns it aside
over the rock ledge in the gap at Unionfalls. At Clayburg, 8
miles below, it meets the north branch and turns abruptly into
the larger valley occupied by that smaller stream. Turned aside,.
probably by depth of drift, the river encounters the ponderous
rock ridge at the High falls, in which it has cut a very con-
siderable gorge, which appears wholly post-glacial. The position
of the preglacial channel hereabout has not been ascertained, a
fairly continuous line of rock outcrops occurring to the northward
and many appearing to the south of the present channel.
Beyond the High falls the valley is again broad and filled with
drift. At Cadyville the river is once more out of its old channel,
and has cut quite a gorge in the Potsdam sandstone at that point.
From Cadyville to the mouth of the river at Plattsburg the fall
is 400 feet and the distance 10 miles, giving a rate double the
average fall of the stream, yet the bottom of the drift-filling is
nowhere reached save at the pulp mill, 2 miles above Plattsburg,
where a long but not deep cut through the Calciferous limestones
has been made, and at Plattsburg itself.
The Racquette illustrates the same features. Its headwaters
are in Racquette, Forked and Long lakes. In its northward
course from Long lake it meets and is cutting through the ridge
88 NEW YORK STATE MUSEUM
at Racquette falls. Beyond, the valley is flat and marshy all the
way to Piercefield, and the river runs in a terrific series of me-
anders. At the mouth of Stony creek it turns a sharp right angle
to the west and flows in that direction to Tupper lake, receiving —
from the south the outflow from Follensby pond, Big Simonds.
pond and Tupper lake, all of these waters are held up by the
level of the Racquette. From Long lake to Tupper lake is a dis-
tance of 20 miles by the valley; far more following the curves of
the river, yet the total fall in that distance is but 70 feet, of which
a large share is at Racquette falls. Beyond Tupper lake, or
rather Piercefield, the river is swift and rapids are frequent.
The valley from Long lake to Stony creek is so exactly in line
with the valley in which Upper Saranac lake lies that it seems.
almost certainly to represent a single line of preglacial drainage.
Yet Indian carry between the two drainage systems, is over a.
rock ridge which seems to bar the way. Though there is prob-
ably a buried channel between the two, it must be constricted.
when compared with the width of the valley on each side.
The St Regis and Ausable rivers furnish equally good illustra-
tions, though the Ausable differs from the rest in having its main
source in the narrow, high level passes of the Marcy group, in
small lakes which lie at altitudes from 400 to 600 feet above the
lakes in which the others take their rise. Even Lake Placid, the
only considerable lake on the Ausable drainage system, has a
level 300 feet above the Saranac lakes. Furthermore it is not
in the main line of the drainage, its outlet being merely tributary |
to the west branck of the Ausable.
The smaller rivers previously referred to, the Great Chazy,
Chateaugay, Salmon and Deer, which drain the wedge-shaped.
tract of country between the diverging courses of the other and
larger streams, differ from them in having their sources near the
outskirts of the hills, so that the greater part of their course lies:
through the plain. Their present channels are determined by the
slopes of that plain, so that on either side of the divide they flow ~
in nearly parallel courses, their tributaries are few and small, and
the interspaces are largely undrained. But their main fea-
+
GEOLOGY OF FRANKLIN COUNTY 89
tures are the same. -Upper and Lower Chateaugay lakes on the
Chateaugay, Chazy lake, in which the Great Chazy rises, and the
many small ponds at the headwaters of the Salmon and Deer
show the flat, poorly drained character of their upper reaches.
Going downstream, frequent falls and rapids occur where the
present channels are not precisely in line with the old ones. The
Chateaugay is out of its former channel for a long distance, and
has sawed a deep, narrow gorge into the Potsdam sandstone,
second only in impressiveness to the Ausable chasm. The Sal-
mon is cutting a gorge at Malone, and has a rock bottom, with
rapids, at several points in Westville. While the still smaller
streams have scraped away the drift down to bedrock in a few
places, they have made no great progress in cutting into the
rock.
PRECAMBRIAN ROCKS
_ The Precambrian rocks of Franklin county are wholly crystal-—
line and have for the most part a foliated, or gneissoid structure.
They consist in large part of rocks which are of unmistakable
igneous orgin, comprising gabbroic, syenitic and granitic rocks;
in small part of rocks of sedimentary origin, coarsely crystalline
limestones associated with certain peculiar and characteristic
schists and gneisses; in large part again of other, mostly finely
granular, gneissoid rocks of unknown age and of uncertain, but
probably of igneous origin. These rocks are in all respects simi-
lar to the Canadian rocks to the northward, from which they are
separated by the interval in which the paleozoic rocks of the St
Lawrence valley are at the surface. In the writer’s judgment,
they are to be as unhesitatingly classed with them as would be
the case were the covering of later rocks to be swept away, so that
they could be followed foot by foot across the intervening dis-
tance.
These Canadian rocks were subdivided into the fundamental
_ gneiss and the Grenville series by Logan, the two constituting
his Lower Laurentian. Both were supposed to consist largely of
sedimentary rocks, and the former was regarded as the older. It
90 NEW YORK STATE MUSEUM
is more uniform in character than the Grenville series, lacking the
limestones, quartzites and certain gneisses which appear largely
in that series and being mainly composed of acid, orthoclase
gneisses.!
In commencing work in the Adirondack region, this classifi-
cation was taken for a working hypothesis. As wurk has pro-
gressed, the gneisses which it was thought might represent Logan’s:
fundamental gneiss have been partially separated into their con-
Stituent elements, and in every case the separated element has
been found to be of igneous origin, and to be intrusive into, and
therefore younger than, the Grenville rocks. This has recently
been strongly emphasized by Smyth, as a result of his work along
the better exposed belts of the Grenville rocks on the west.”
There still remains, however, a great body of gneiss of uncertain
relationships, evidence respecting its age not being forthcoming
as yet. Nor has its origin been demonstrated, though apparently
no sedimentary rocks are represented in it, the gneisses through-
out having the mineralogy and composition of igneous rocks. It |
may then be said that no rocks have been found in the northern:
Adirondacks which can be shown to be older than the Grenville
series, but that in every case in which the relations have beer
made out, the adjacent rocks show intrusive contacts with the
Grenville rocks. On the other hand, that is a sedimentary series
and must have been laid down on some floor.
The latest conclusions of the Canadian geologists respecting the
similar rocks in their territory are of great interest in this con-
nection. In a recent report on the geology of the area to the
north of Montreal, Prof. F. D. Adams says: 3
Whether all these gneisses really form a portion of the floor
en which the Grenville series was deposited, since brought up by
folding and erosion, and thus entitled to the appellation “ funda-
mental gneiss ”, or whether they are intrusive masses, folded by
the pressure to which the whole region has been subjected, cam
not be determined.
1Geology of Canada. 18638. p. 889.
215th an. rep’t N. Y. state geologist. 1895. 1:481-97.
3Geol. sur. Canada, new series. vy. 8, pt J. p. 8-29.
GEOLOGY OF FRANKLIN COUNTY OL
In a somewhat more recent paper by Dr A. E. Barlow the rela-
tions between the “Laurentian” and the Grenville series are thus.
described :+ ;
The relations of these two members of the archaean in ventral:
Ontario suggest in the strongest manner that in the Grenville
series we have a truly clastic group of strata which has slowly
sunk down into, and have been invaded by, much greater volumes.
of the granites and gneisses of the Laurentian when these latter
were in a plastic condition. . . The contact between the
gneisses and granites of the Laurentian on the one hand, and the
limestones and associated rocks of the Grenville series on the
other, is, wherever examined, one of intrusion.
There are three possibilities in regard to the age of the undeter-
mined gneisses of Franklin county, their igneous origin being
-admitted. |
1 They may in whole or part represent a more ancient series:
than the Grenville.
2 They may represent a somewhat later series intrusive in
the Grenville, but older than the great gabbro, syenite and granite:
intrusions.
3 They may represent thoroughly foliated phases of these later
intrusions.
In the writer’s present judgment they will be found to belong
partly under 2 and partly under 3 but more specially the former.*
All the later intrusions, so far as examined by the writer, while
quite gneissoid, show at least rather massive cores, though the
- anorthosites are much more massive than the more acid rocks.
But in northern Franklin county are wide areas of rather fine
grained gneisses in which no such cores are visible. Furthermore
these gneisses, and the Grenville rocks as well, are cut by numer-
ous dikes of a peculiar and very characteristic, rusty-looking
gabbro-diorite or norite diorite, while not a single case of such a
_ dike has yet been seen cutting the anorthosites, nor the syenites
and granites. A large dike of this character. is found at the
summit of Catamount mountain, in Clinton county, in a rock
which resembles the later granite, though it has not been shown
1iBarlow, A. E. Ottawa naturalist. Feb. 1899. 12: 205-17.
2It is by no means impossible that in part they belong under 1.
92 NEW YORK STATE MUSEUM.
‘to be such. This is the only occurrence yet noted which may
possibly invalidate the preceding statement. At the best this is
only negative evidence, but it is desired to call attention to the
possible light which these dikes may shed on the age of the
gneisses. . .
Grenville series
Rocks which can be referred with certainty to the Grenville
‘series are but sparingly shown in Franklin county, and occur in
‘small disconnected patches instead of considerable belts.1 But
eight areas of sufficient size to appear on a small scale map have oi
een noted, and of these six occur surrounded by rocks which are
unquestionably igneous, and are not only of later date than the
‘Grenville rocks but probably of later date than those gneisses
whose origin is questionable. Inspection of the map shows that
six of these eight patches have such position with respect to one
-another, that they seem to represent remnants of what were origin-
ally two continuous and parallel northeast and southwest belts,
suchas are now found in St Lawrence county infolded with other
gneisses. Here in Franklin they have been invaded by great
igneous intrusions, and all save these mere patches have disap-
peared. The contrasting conditions in the two counties can
quite plausibly be explained by supposing that a greater erosion
has taken place in Franklin county, so that rocks originally more
deeply buried are now.exposed at the surface there, whence it
would follow that similar conditicns now exist in St Lawrence at
some distance below the surface. It should be said also that the
fact of greater erosion in Franklin county is supported by inde- —
pendent evidence, instead of being a mere supposition brought
forward for the purposes of this explanation. |
Rocks of the Grenville series. The most striking and character-
istic rocks of the Grenville series are the limestones. These are
coarsely crystalline marbles which contain, even when purest,
scales of graphite and phlogopite and grains of green pyroxene,
and often apatite and titanite as well. Some very pure-looking
beds prove to be composed of nearly equal parts of calcite and
1See map accompanying this report.
LSUM WI OL SUIIN WOU NHWS SV ‘OO NOLNIIOD “dIHSNMOL MOOUM MOVIE “NIVINQOW LNOOWV LV)
Vv 781d
GEOLOGY OF FRANKLIN COUNTY 93
white pyroxene, and it is by the alteration to serpentine of the
latter mineral that the ophicalcites of the series are produced, as.
was long ago shown by Merrill.1_ These beds of limestone vary
much in thickness in different places, but no evidence has been:
forthcoming in Franklin county to throw any light on the number-
of limestone beds or the possible thickness of the series.
Beds of pure limestone have been noted at only two localities in.
the county, at Franklin Falls and in the southern part of Malone-
township. At the old kiln near the Saranac river, 2 miles below
Franklin Falls a massive bed outcrops, which is exposed for 100:
yards across the strike, denoting a thickness of at least 150 feet
if the dip is continuous throughout. As their outer surfaces are-
approached, the limestones become very impure, containing great
quantities of green pyroxene and much quartz, with often scapo-
lite and white pyroxene as well. Precisely similar beds are often
found inclosed in gneisses and wholly apart from any large lime-
stone bed. Good exposures of such are found by the roadside one-
half mile north of the bridge at Franklin Falls (see pl. 5). They
weather rapidly on account of the leaching out of the calcite, and
are among the most characteristic rocks of the series.
Quartzites have not been noted in Franklin county. Very
quartzose gneisses occur which hold invariably a respectable per-
centage of orthoclase. An evenly granular, rapidly disintegrat-
ing, white gneiss which usually contains much graphite and con-.
sists essentially of quartz and white pyroxene, often with consider-
able pyrite, is a very common rock in this county, associated with:
the limestones, and is a decisive indication of the presence of the-
series in places where the limestones are lacking. Scapolite is a
quite common mineral near contacts, and some of the quartz-
white-pyroxene gneisses hold abundant scapolite. Graphite is a
very important mineral in the diagnosis of this series, occurring in ©
many of the gneisses as well as in the limestone. But some care
is necessary in localities where exposures are meager, since this.
mineral also is found sparingly in some of the more acid igneous
rocks. Sillimanite is another quite characteristic mineral,
Merrill, G. P. Amer. jour. sci. Mar. 1889. 37: 189-91.
94 NEW YORK STATE MUSEUM
though it is not frequent in the Adirondacks in the writer’s ex-
perience. Certain very garnetiferous, hornblende gneisses are
very frequently associated with the limestone, though there are
many other rocks rich in garnets, notably many gabbroic gneisses, —
‘so that such beds are by no means diagnostic of the series in the
absence of others. In fact it is quite probable that much, if not
all of such gneiss, when in association with the limestones, has
‘been formed from gabbro intrusions.
These characteristic Grenville rocks are interbanded and inter-
folded with other gneisses which are precisely like rocks that ~ :
occur over wide areas in which all trace of the Grenville rocks is
absent. These are various, mostly fine grained, granitic, syenitic —
and gabbroic gneisses, so called since they have the mineralogy
and composition of these igneous rocks, and have already been
referred to as gneisses of doubtful age and origin. Some of these
rocks associated with the limestones are so finely granular that —
they strongly resemble sandstones of various colors in the field, —
‘but the microscope always dispels this impression, absolutely no
indication of clastic structure being visible, while the mineralogy —
is that of the igneous rocks above noted. In the writer’s ex- —
‘perience an abundance of these fine grained rocks is fairly indic-
ative of the presence of the limestones near at hand, at least
they have not been met with abundantly away from them. But,
if thig fineness of grain be a constant difference, it is the only one,
-and such rocks are provisionally regarded as the equivalents of
the other gneisses, representing dikes and sheets injected into
‘the Grenville rocks which have been given a parallel foliation and
an interbedded appearance by subsequent metamorphism. Their
more finely granular structure may perhaps be accounted for as
:a result of their proximity to the limestones, and to the yielding ©
character of the latter under the severe pressures producing the
metamorphism. | ees
It is not to be supposed that anything like all the patches of
the Grenville series are represented on the map.t The country
DNase at) ne aed Simm Pen Ya
1The Malone and Waverly patches undoubtedly are of much greater
extent than is indicated on the map. To the southwest of each is a wide
:area of flat country with no outcrops, indicating Grenville rocks below.
Ri 4 ‘STIVYA NITMNVUA FO HLUON SHIUGS ATTIANAUDH AO SUNOLSHWIT Hund Wwy{
ae ee Oe eee
; ~*~ = ,
ae Fo
ee
~
GEOLOGY OF FRANKLIN COUNTY 95
has not been thoroughly traversed in the first place, and more-
over the rocks are readily eroded and show only meagerly in out-
crop. Three of the patches indicated on the map may have
greater extent than there shown, as they are in line with areas of
little relief in which no outcrops could be discovered.
The Franklin Falls, Saranac village and Follensby pond
patches constitute the more southerly of the two northeast and
southwest belts previously mentioned. It will be seen from the
map that the depression occupied by Lower and Middle Saranac
lakes (the latter usually called Round lake) is on the same line
and with the same trend. Since no rock save anorthosite is ex-
posed along these lakes, and the exposures are practically con-
tinuous around the shores, with numerous islands of the same
rock, this concordance in trend may be a mere coincidence, but it
at least suggests strongly that the depression may have been
initiated by the presence of a continuous belt of the Grenville
rocks along this line.
| Doubtful gneisses -
Rocks which must be referred to this group are exposed pretty
continuously across the county from east to west, in the northern —
part of the Precambrian area, and as found near the Potsdam
boundary have been briefly described in a preceding report.
Rocks differing widely in character, and not improbably consider-
ably in age, are included in this category, which, as at present
used, Serves aS a convenient receptacle in which to place all
gneisses whose origin and relations are undetermined. In other
words it is a temporary expedient in mapping, made necessary by
the difficult character of the region. It is quite certain that, as
present mapped, many small areas of the later granite are in-
cluded, the term later being made use of simply to express the
_ possibility of there having been two periods of granite intrusion,
the earlier representatives being more gneissoid than the later.
‘These areas are too small and with too indefinite boundaries to
‘appear on a small scale map. On the assumption that these
gneisses are of igneous origin, they are readily separated into
-1Cushing H. P. 16th an. rep’t N. Y. state geologist. 1896. p. 16-21.
96 NEW YORK STATEH MUSEUM
varieties, corresponding to certain igneous rocks. There are thus
granite, syenite, diorite and gabbro gneisses, together with plenti-
ful intermediate varieties. Sometimes one variety will prevail
alone over a considerable area, but more commonly in Franklin
county two or more will occur in alternate bands, sometimes of
very slight width, rendering the areal mapping of the ec
varieties an impossible task.
A very significant fact in its bearing on the origin of these
gneisses is that in every case their mineralogy agrees precisely
with that of certain igneous rocks, and the same holds true of their
chemical composition in the few cases in which they have been
chemically examined. While this is by no means decisive evidence
in rocks so excessively metamorphosed, it seems improbable
that beds of the extent and thickness of these should have been
formed by deposition in water, with so little change in composi-
tion, in other words from material so largely unweathered. These
rocks are thus sharply marked off from the characteristic Gren-
ville rocks, concerning which neither of the above statements is
true.t
These gneisses are characterized in the large way by a rather
evenly granular structure and are usually fine grained, though
with considerable variation in this respect. Some of them show
traces of cataclastic structure, but this is the exception. Many
of them perfectly resemble the more finely grained portions of
rocks to be described later, which are regarded, both by the Cana-
dian and New York geologists, as of undoubted igneous origin.
Orthoclase-quartz (granite) gneisses. The most widespread of
the gneisses is a fine grained, red, acid rock composed essentially
of alkali feldspars and quartz, with magnetite always present,
and usually small amounts of hornblende or biotite. The feldspar
is ordinarily microperthite or microcline, but some orthoclase is.
always present and it may predominate, while a little acid
plagioclase is usually to be found in addition. Hornblende is the
usual dark silicate, biotite being much less common.
1Cf., Adams, F. D. Geol. sur. Canada. New series. v. 8, pt J. p. 35-85.
~
:
ar.
ql
~ GEOLOGY OF FRANKLIN COUNTY 97
These rocks have at best only a very obscure foliation. They
are cut by numerous quartz and pegmatite veins, and frequently
become quite coarse themselves for a short distance.
Two types of structure are found which grade into one another.
In the first type there are evidences of cataclastic structure.
Larger feldspars occur, which become broken down at the edges,
producing fragments whose origin from the parent fragment is
often apparent. But no instances have been seen in which this
structure is well marked, as in the case of the similar gneiss from ~
Trembling mountain cited by Adams.! In much of the gneiss in
fact, little or no sign of this structure is observable, but the feld-
spars are even sized, with highly irregular boundaries against one
another, which often become very jagged and interpenetrate.
The quartz occurs largely in small idiomorphic individuals in-
_ cluded in the feldspars, this being the case in the rocks with no
sign of cataclastic structure, but only to a slight extent in the
other type. The remaining quartz consists of fairly large indi-
viduals, always with rounded outlines, and usually of elongated,
often greatly elongated, shape. These spindle-shaped quartzes
‘are optical wholes, though showing pressure effects by an un-
dulatory extinction which is not uniform over the whole but
breaks up the crystal into several patches. It seems to the writer
that the peculiar shape and character of the quartz is best ex-
plained as a result of a slow recrystallization, molecule by mole-
cule, under the stresses of metamorphism, the optical anomalies
shown resulting from slight subsequent strains applied to the
rock.
In many parts of the region gneisses are found which are
precisely like those here described except that they contain
pyroxene in addition to the hornblende. Between these and other
gneisses composed essentially of pyroxenes and feldspars, which
are, next to the granitic gneisses, the most widespread rocks of
this group, many intermediate varieties occur.
1Adams, F. D. Geol. sur. Canada. New series. v. 8. pt Jd. p. 42.
98 NEW YORK STATE MUSEUM
Pyroxene gneisses, or granulites. These rocks are usually found
interbanded with the granitic gneisses in Franklin county, the
bands ranging from a few inches to many feet in thickness.
Occasional large masses occur but are rather exceptional. They
are gray to black, rarely red, in color and consist of pyroxene
(both augite and hypersthene usually) and plagioclase and ortho-
clase feldspars as essential constituents, often with hornblende
as well. Quartz is present at times. Petrographic descriptions
of several of the varieties which these rocks present have been
recently published by Adams, and need not be repeated in a report
of this preliminary character: The rocks are rather evenly
granular, show little or no sign of cataclastic structure, and vary
considerably in mineralogy from place to place.
These granulites are mainly confined to the northern part of
the county, where they occur interbanded with orthoclase
gneisses, or occasionally in rather large masses. In Malone and
Belmont they are of gray color and consist of pyroxene (both
hypersthene and aegirin-augite), orthoclase and a plagioclase
which varies from oligoclase to andesine. If present at all, horn-
blende is in only slight amount. Sometimes the orthoclase, at
others the plagioclase feldspar predominates, and each may
appear to the exclusion of the other. Similar rocks are wide-
spread throughout the Adirondack region.
In Brandon and Dickinson better foliated, black gneisses, com-_
posed essentially of hornblende and andesine feldspar, accompany ~
the orthoclase gneisses, and the pyroxene granulites are scarce.
These hornblende gneisses frequently contain augite or hypers-
thene or both, thus showing a gradation into the pyroxene rocks.
These gneisses are also extremely common in the Adirondacks.
They have the mineralogy of diorites, or gabbro-diorites. They
- are absolutely not to be distinguished from hornblende gneisses:
of frequent occurrence which are unquestionable derivatives of
the gabbros, described on a later page. In many localities such
rocks are found containing an unchanged core of the igneous rock
with characteristic ophitic structure, from which a gradual trans-
1Geol. sur. Canida, An. rep’t, v. 8. pt J. p. 73-82.
ee: .
Es —r
GEOLOGY OF FRANKLIN COUNTY 99
ation may be traced within a few feet into the hornblende gneiss,
which has been produced by the metamorphism of the latter. An
excellent locality for such exposures is the west shore of Upper
Chateaugay lake at the point where it narrows into the outlet.
Another is a cut on the Northern New York railroad 2 miles south
of St Regis Falls. |
It is however the exception when the hornblende gneisses can be
traced to a connection with the gabbros. The question at once
arises whether there are hornblende gneisses of two distinct ages
or they are all to be considered as derived from the gabbro. This
question can not be answered as yet, though the writer rather
inclines to the first alternative. Such gneisses are excellently
shown around Dickinson Center, interbanded with the orthoclase
gneisses in such fashion as to produce a strong impression that
the latter represent granitic intrusions into the former, the whole
drawn out and foliated by the metamorphism.
Later eruptives
To a considerable extent the Precambrian rocks exposed in
Franklin county are younger than the Grenville rocks, and
younger than most, at least, of the doubtful gneisses as well.
These rocks are all of igneous origin, occurring as immense in-
irusive masses or as dikes, which show eruptive contacts against,
and also include masses of the Grenville rocks and of the gneisses.
Most of them have been metamorphosed and given a foliated struc-
ture, so that they are gneissoid, but frequently massive cores re-
main, into which the gneisses can be traced by a gradual trans-
ition. Quite similar gneisses also occur with no apparent massive
core, and the recognition of such and their separation from similar
phases of the earlier gneisses, as well as the accurate mapping of
the boundaries of the intrusions themselves is often a matter of
the greatest difficulty. These eruptives comprise rocks of the
gabbro, syenite and granite families.
Anorthosites. The name anorthosite was given by F. D. Adams
to eruptive rocks which occur widely in eastern Canada, are re-
lated to the gabbros and consist almost wholly of labradorite
100 NEW YORK STATE MUSEUM
feldspar. Similar rocks are extensively exposed in the easterm
Adirondacks. They are at the surface over a large part of Essex
county, and it has long been known that they extend into Frank-
lin, an attempt to indicate their probable limits being made by
Merrill in 1894.1. One of the surprises of the recent field work in:
the county has been the very considerable area occupied by them,.
they running considerably beyond the limits assigned to them by
Merrill from the very limited information at his command.
The anorthosites in the main are coarse to very coarse grained’
rocks consisting almost wholly of labradorite feldspar, whose-
large blue black crystals frequently reach a length of 3 inches:
and occasionally are a foot long or more. Not infrequently the
crystals show the iridescent play of colors so often seen in this-
mineral, but nothing of the sort has been noted which will for a
moment compare with the Labrador or Norway material. The:
extinction angles of the feldspar show that it is mostly labradorite
though occasional angles of 30° and over indicate that more basic
feldspars are also present in slight amounts. As accessory min-
erals ilmenite, apatite, titanite, garnet, augite, hypersthene, horn-
blende, biotite, pyrite, pyrrhotite, chalcopyrite and a little ortho-
clase and quartz have been noted, the two latter occurring only
in minute patches in the sort of intimate intergrowth known as
granophyr. Ilmenite, augite, hornblende and one of the three
sulfids are the usual accompanying minerals, the others are only
occasional and all are in slight quantity. | )
_The structure is cataclastic, that is the rock has been subjected
to great stresses, while deeply buried beneath other rocks since
worn away, which have had the effect of more or less completely
breaking down the large crystals into a multitude of small frag-
ments, while at the same time the great pressure of the overlying:
rocks kept the rock at all times in an unyielding condition, instead
of permitting it to be crushed to loose fragments. All grades of
this occur from very coarsely crystalline varieties, with only a
little granular material around the edges of the crystals, to those -
in which the granulation is quite complete, few or no large —
1Merrill, F. J. H. Economic and geologic map of the state of New York.
GEOLOGY OF FRANKLIN COUNTY 101
crystals remaining. In general the extreme varieties arerare, most
-of the rock consisting of partially granulated material. . There is
also considerable variation in the fineness of the granulation itself
‘in different parts of the rock, giving it a quite different appear-
ance. The granulated portion is commonly greenish or greenish
white in color, presenting a strong contrast to the blue black
-crystals.
As the peripheral portions of the anorthosite intrusions are ap-
proached, the dark silicate minerals become more abundant, so
‘that the rock, while still very feldspathic, can not be regarded as
wholly made up of that mineral. It occupies in fact, an inter-
‘mediate position between typical anorthosite and gabbro,in which
rock the augite plays as important a role as the labradorite, and
may be called anorthosite-gabbro. The passage from one rock
‘into the other is a gradual one, and has clearly resulted from a
‘slight differentiation in the original intrusion during the process
-of cooling. |
Along with this progressive change in composition often goes
-one in structure, the rock becoming on the whole less coarsely
-erystalline and usually somewhat gneissoid. The large labra-
-dorite crystals decrease in size and are less frequent. Not infre-
‘quently this change is carried so far that a distinct, rather fine
‘grained gneiss results, of totally different appearance from the
-original rock, the only clue to its origin being the possibility of
tracing it through intermediate varieties into the undoubted
anorthosite, and the fact that it still contains occasional augen of
‘dark blue labradorite. This rock weathers much more readily
‘than does the anorthosite, and has a brown rusty look which
‘causes it to appear more weathered than is really the case. In it
“‘hypersthene is often more abundant than augite, which is seldom
‘the fact in the main mass of the intrusion, so that the rock is a
norite rather than a gabbro. Except for the labradorite augen,
which may ultimately disappear, these brown gneisses exactly
resemble gneisses which belong with the syenites, shortly to be
‘described, as well as certain gabbro gneisses which occur asso-
ciated with the Grenville limestones. When anorthosite and
102 NEW YORK STATE MUSEUM
syenite areas adjoin, each showing these peripheral phases, it is:
an impossible matter sharply to delimit their boundaries in map-
ping. | :
In some cases hypersthene, augite and garnet, with or without
biotite and hornblende, constitute such a large portion of these:
peripheral rocks that they become true gabbros or norites in com-
position, so that one can pass from anorthosite to gabbro in going
from the center to the exterior of a single intrusive mass.
Wherever anorthosite is the surface rock, exposures abound.
As indicated on the accompanying map, a large area in the south-
eastern part of the county is wholly occupied by this rock. It is
cut by numerous dikes, later to be considered, but these are almost
without exception of no great size. It appears in a series of east
and west ridges, which attain high altitudes in the extreme south-
east with Mt Seward and Ampersand mount as the culminating:
peaks; in the lake belt the relief is but slight, the majority of the
ridges not being more than one or two hundred feet above the
water surface, with the comparatively low peaks of Boot Bay and_
Long Pond mountains representing the highest points; to the west
of the lake belt the extent of the rock is not great, but the ridges.
are higher, culminating in St Regis, Jenkins and Ore-bed moun-
‘tains. Abundant exposures occur about the Saranac and St Regis:
lakes and the host of ponds in the lake belt, the trend of the ridges.
being at right angles to the trend of the larger lakes, and result-
ing in the production of their extremely irregular shore lines.
Exposures are so much more abundant, than where the gneisses or
the Grenville rocks are at the surface, that the passage from the
one to the other may be inferred from this alone where outcrops
are not forthcoming. }
The northern boundary of the anorthosite is very plain, unmis--
~ takable anorthositic rocks adjoining closely rocks of totally
different character. On the south and southwest this is not the:
case, the rock fading out into the augen gneiss already described.
This change is well shown by the exposures along the Racquette —
river going either west or south from the big bend at Axton, where:
anorthosite-gabbro is exposed. Going west, the last of the augem
yy 4
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GEOLOGY OF FRANKLIN COUNTY 103
_ gneiss is found from 2 to 3 miles below Tromblee’s and is found
well exposed along Follensby pond. Going south, the last of it
_is found. in the gorge at Racquette falls. In all these places con-
siderable fairly coarse anorthosite-gabbro is found along with the
granular gneiss, and the only explanation that will fit the
phenomena in the writer’s judgment is that the augen gneiss is
derived from the coarser rock by crushing.
‘Whiteface type of anorthosite. Mt Whiteface in Essex county is
composed of a gabbroic rock of peculiar appearance, which has
been dubbed the Whiteface type by Kemp, to distinguish it from
the usual rock of the Mt Marcy type This rock gets over the
border into Franklin county at Franklin Falls, and also runs into
the corner of Clinton on Catamount and Wilmington mountains.
This rock differs from the ordinary anorthosite in many re-
spects. It is usually completely granulated, though occasional
feldspar augen indicate a cataclastic structure. The feldspar is
white in color, the green tinge of the granulated feldspar in the
-usual variety not appearing. The dark silicates are more promi-
nent, and the rock is usually markedly gneissoid. They are irreg-
ularly distributed, parts of the rock being nearly free from, and
parts heavily charged with them. The white color, even when the
rock is weathered, is in strong contrast to the green and rusty
brown shades of the gneissoid parts of the other rock.
Under the microscope the chief difference is found in the pre-
dominance of hornblende among the ferro-magnesian silicates.
Next in abundance comes a green augite. No hypersthene has
been noted. The feldspar is mostly labradorite, as shown by
maximum extinctions of from 22° to 27° from the albite twining
plane in sections which extinguish equally on both sides. The
accessory minerals are the same as in the ordinary anorthosite,
iron ores, zircon, apatite, titanite, garnet, biotite and sometimes
a little quartz. The structure is cataclastic and the feldspars
show marked strain phenomena, the twining lamellae being bent,
often pinched out or else largely disappearing. In many slides.
1Kemp, J. F. 15th an. rep’t N. Y. state geologist. 1895. pt1. p. 587. Ibid.
Bull. N. Y, state museum no, 21. 5:57,
104 _ NEW YORK STATE MUSEUM
unstriated feldspar abounds but is regarded as labradorite with
all appearance of twining destroyed by strain.
The localized occurrence of this rock, together with its constant
peculiarities, disposes the writer to consider it as a separate intru-
sion, probably slightly later than the ordinary anorthosite in time.
The evidence for or against this view can be obtained only from
Essex county, if there. In Franklin county the only exposures
occur in the vicinity of Franklin Falls, the best being along the
river. Grenville limestones lie close at hand to the north and
east, and, as they are approached, the rock becomes rapidly more
basic, passing into a gabbro-gneiss of dark color, with a foliation
parallel to that of the succeeding Grenville rocks. |
On the west end of Catamourt mount, 5 miles east of Franklin
~ Falls, in Clinton county, this Whiteface type is exposed, sur-
rounded on the north and east by the same gabbroic gneiss as at
Franklin Falls, this being followed by a red, granitic gneiss
toward the top of the mountain, with no contacts showing so far
as the writer has been able to discover. In this gabbro-gneiss
occasional augen of blue labradorite appear; in one place a con-
siderable face of rock like the Marcy type of anorthosite-gabbro
was seen, and near at hand, inclosed in a rotten brown gneiss, was
an unmistakable inclusion of ordinary anorthosite with numer-
ous blue labradorite augen, some of quite large size and iridescent.
The locality is very suggestive, but unfortunately the precise
nature of the inclosing rock is obscure on account of its decom-
posed condition. It is connected with, and seems to be a phase
of, the dark gabbro-gneiss rather than connected with the main
mass of the typical Whiteface anorthosite, and the question of the
relationship of this gabbro-gneiss is still an open one. From its
distribution around the edge of the Whiteface anorthosite it
would seem to represent merely a differentiation phase of that
rock, which would then be younger than the ordinary anorthosite.
It strongly resembles the gabbros whose consideration follows,
and may belong with them, in which case its apparent close re-
lationship with the Whiteface anorthosite may have a much
broader significance. Or the inclusion may not be an inclusion
GEOLOGY OF FRANKLIN COUNTY 105
at all, but of the nature of a mammoth auge, an uncrushed portion
of the original rock whose granulation and stretching produced
the gneiss: The brown gneiss and anorthosite taken together
furnish a combination which resembles extraordinarily some of
the augen gneiss exposures along the Racquette already described.
We can not answer these queries at present. In rocks so meta-
morphosed and changed the precise nature of such exposures as
these is seldom clear.
Syenites. While the presence of great bodies of gabbroic in-
trusive rocks in the Adirondacks has long been known, it is only
very recently that evidence of similar intrusions of syenitic rocks
has been forthcoming.t. This is for the simple reason that the
rock is by no means so easy of discrimination, being highly varia-
ble, usually gneissoid, weathering much more readily, and in
weathered condition closely resembling other rocks of apparently
wholly different relationships.
These rocks are widely exposed in Franklin county. When
fresh they are of green or greenish gray shades, of considerable
variation in grain, though never presenting very coarse phases
comparable to the anorthosites,and usually of markedly gneissoid,
or else of linear structure. While there is often evidence of cata-
clastic structure, it is exceptional that any considerable feldspar
augen remain, and usually considerable recrystallization has
taken place. ‘The contrast with the anorthosites in these respects
is so marked that some explanation must be sought in an original
difference between the two rocks, as they are of about the same
age and have therefore been metamerphosed under similar condi-
tions. It is thought to be due simply to an original difference in
coarseness of crystallization,, the excessive coarseness of the
anorthosites rendering complete granulation a matter of much
greater difficulty.
As is the case with all the intrusive rocks of the district, com-
paratively massive cores of less changed rock are of not un-
common occurrence. The most foliated rocks are those with con-
1$myth, C.H,, jr. Bul, geol. soc. Amer. 6:271-74.
—— 17th an. rep’t N, Y. state geologist. 1897, p, 471-486,
Cushing, H. P. Bul. geol. soc, Amer, 10: 177-92
106 NEW YORK STATE MUSEUM
siderable content of the black, ferro-magnesian silicates. In the
more quartzose rocks these are present in only slight quantity,
and instead of foliation a linear structure appears, due to the
drawn out, spindle form which the quartz assumes.
These rocks rapidly undergo a color change from green to
brown on exposure to the weather, though greenish nodules may
frequently be found in the brown rocks. This color change may
occur without perceptibly impairing the freshness of the constitu-
ent minerals. Usually however the hypersthene (or bronzite),
and often too the augite are found to be more or less decayed in
the brown rocks. These brown gneisses cover a wide area in
Franklin county, and, while in part they are easily recognizable
as belonging with the syenites, in other part they are puzzling,
and may or may not belong here. It thus becomes a very difficult
matter to determine the precise limits of the main intrusions and
in the case of smaller patches to determine at all whether the
rocks belong in this group. Furthermore, the ground has not
been exhaustively studied, so that the limits of these rocks as
shown on the map are in a high degree provisional. The main
areas are indicated, but there is question as to their precise ex- |
tent. In general doubtful varieties occurring in close association
with undoubted syenites have been classed with them; those with
no such association have not been so mapped.
There is much local variation in structure and composition in
these rocks, reminding one of the similar variations which are so
characteristic of the gabbro group. This local variation hampers
the endeavor to determine whether differentiation has taken place
in the main intrusions so that no certainty has been reached in
regard to it. It is however believed that such has been the case
_ and that the associated granites will be found more massed
toward the centers of the intrusions. All intermediate stages be-
tween granite and syenite may be found so that there is evidently
a passage of one rock into the other. These granites are either
red or green in color, and while very quartzose and poor in dark
silicates, these are the same as appear in the syenites, and the
quartz has the same spindle form. . Rack |
GEOLOGY OF FRANKLIN COUNTY 107
The most common rock is a quartz-augite-syenite, composed .
essentially of microperthitic feldspar (orthoclase and albite or
ligoclase), augite, hypersthene or bronzite and quartz. Horn-
blende is almost always present as well, and in a considerable
‘portion of the rock comes to exceed the augite in quantity. In
these hornblendic varieties the hypersthene is usually absent, and
ordinarily some biotite appears. Quartz is usually present, as
it is in the augite syenite. The two varieties shade into one an-
other with facility.
Accessory minerals are zircon, apatite, magnetite, pyrite, garnet,
titanite, allanite, and oligoclase feldspar. Garnet occurs but
sparingly and, so far as noted, only as corrosion rims around
magnetite. Its scarcity is in strong contrast to its abundance in
‘the gabbro rocks. On the other hand titanite, rare in the gabbros
and anorthosites, is here quite characteristic, while the rare allan-
ite does not occur in them at all so far as noted. :
The green augite and the brounzite (or hypersthene more rarely)
are often minutely intergrown in thin parallel plates, and, while
the minerals themselves and the hornblende as well are closely
like the same minerals in the gabbro rocks, these intergrowths
have not been observed in them and seem quite characteristic of_
‘the augite syenites.
The greater part of the feldspar consists of the minute inter-
growth of orthoclase and an acid plagioclase to which the name
2 microperthite ” ig applied. The plagioclase is usually albite. A
little oligoclase is usually present in addition to the microperthite.
No microperthites with oligoclase cores, similar to those described
by Smyth in the augite syenite at Diana, in Lewis county, have
deen seen in Franklin county.
Quartz seems to be present in all the syenites of the county,
though in the more basic varieties it is in only slight amount and
‘wholly in the form of small inclusions in the feldspars, such as
are frequently found in the feldspars of the entire group. But, in
addition, in the more acid members is much coarse quartz, which
in a large part of the rock assumes the elongated, spindle form
already alluded to.
108 NEW YORK STATE MUSEUM
There is no question that a more detailed investigation of these
rocks will necessitate their subdivision into a number of minor —
types, some of which may be sharply marked off from one another
and represent wholly separate intrusions. Pending such investi-
gation, it is unwise to attempt subdivision. It may be said that
these rocks vary exceedingly from place to place, both in com--
position and in structure, often with great rapidity, recalling the
gabbros in this respect. In part they are granites, in much
larger part augite or hornblende syenites, both with and without
quartz. So far as they have been carefully studied, all the
syenites of Franklin county belong to the type of these rocks com-
prised under Brogger’s name akerite.
The main areas of syenite in the county are indicated on the
accompanying map, and may be called the Loon lake, Tupper
lake, St Regis river and Salmon river areas. The Loon lake area
may prove to fall into two distinct areas on farther study, the:
second of which may be called the Saranac river area, excellent
exposures appearing along the river from Franklin Falls up
nearly to Saranac.
Extending northward from Franklin Falls and thence along
Alder brook as far as the north branch of the Saranac, is a chaim
of low hills of a peculiar, coarse, brown gneiss, which is regarded
as belonging to the augite syenites, though so weathered that it
is almost impossible to get fresh material. In the one or two
places from which such has been obtained, as from the roadside
near Alderbrook postoffice, it ig not quite certain that it is of the
same rock; but, if so, it is augite syenite. These brown rocks:
vary from place to place quite as the ordinary syenite does, and
differ mainly in the less pronounced spindle form. of the quartz.
when present. The hills formed of this rock are low but very.
steep sided, producing an unmistakable topography from which
the character of the rock may be predicted with certainty (see
pl. 6). The rock has cataclastic structure, is certainly igneous,
. and is a syenite, in large part a quartz-augite-syenite, though oftem
with much hornblende.
vg
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MIIASTITIIUYUH GNV MOOUG UACIY NOUMLAA AVOU UVHN ‘SSINNS GLINGAS NMOUE AO TIT
9 Pld
GEOLOGY OF FRANKLIN~COUNTY 109
A small mass of an ordinary quartzose augite syenite, quite like
much of the rock around Loon lake, occurs near Lower Chateau-
‘gay lake in Belmont township. Quite likely similar small in-
trusions will be found elsewhere when the county is more care-
fully surveyed. —
The precise age of these syenite intrusions is not yet known.
At Loon lake they cut the Grenville rocks,! and elsewhere the
doubtful gneisses, and are hence younger than either. The
-gabbros to be next described have been reported by Smyth as
cutting the Diana augite syenite in Lewis county.” The syenite
is therefore older than these gabbros. The unsettled point
concerns their relation to the anorthosites. As to this, evidence is
go far lacking in Franklin county, and so far as the writer is
aware in the rest of the Adirondacks as well. The areal distribu-
tion of the two in Essex and Franklin counties is however so
involved, that localities will certainly be found in which this im-
portant evidence will be forthcoming. The main difficulty arises
from the puzzling peripheral phases which both rocks exhibit.3
Gabbros. These are basic and dark colored, often black, rocks
of quite variable composition and structure. Though their areal
extent is not great, they are of common occurrence throughout
the Adirondacks, and have been more frequently and exhaustively
described than any of the other igneous rocks of the region.*
As seen in Franklin county these gabbros occur either as dikes
or aS small intrusive bosses. They are wholly distinct from the
gabbro-gneisses which occur as border facies of the anorthosites.
The dikes are the more common, but the bosses are by no means
infrequent, and beyond doubt many more remain to be discovered.
The dikes are almost without exception very fine grained, black
1Cushing, H. P. Bul. geol. soc. Amer, 10:185.
2Smyth, C. H. jr. Bul. geol. soc. Amer. 6:283,
3Kemp, J. F. Bul. N. Y. state museum no. 21. 1898. 5:283.
4Kemp. J. F. Amer. jour. sci. Aug. 1892. 44:109-14.
Bul, geol. soc. Amer, 5:213-24,
Smyth, C. H. jr, Amer. jour. sci. 1894, 48:54-65,
—— Bul. geol. soc. Amer. 6:268-83.
Amer. jour, sci., 4th ser, 1:273-81.
110 NEW YORK STATE MUSEUM
&
rocks. The border parts of the ‘bosses are quite similar, but
centrally they are much coarser, are more feldspathic, are of gray
color spotted with black, and their characteristic ophitic structure
and corrosion rims are at once evident to the eye.
As a result of the metamorphism which they have undergone,
these gabbros are in large part converted into amphibolite
gneisses. Most of the bosses show a comparatively unchanged
core, from which a regular gradation in structure and minerah 3
content into the amphibolite can be traced. In some the conver-
‘sion is almost complete, but these usually furnish material fron»
their central portions which exhibits traces of the original miner-
als and structure in thin section. ‘Still others show no such traces,
and these last are, with our present knowledge, absolutely not
to be distinguished from other amphibolite gneisses which have —
been provisionally classed with the doubtful gneisses and already ;
described. Quite similar rocks occur also in close association
with the crystalline limestones and graphitic gneisses of the
Grenville series. The writer regards them all as metamorphosed
igneous rocks, either gabbro or some related rock, but believes
these last to be much older than the gabbros immediately under
discussion. Certain small areas of amphibolite are met with,
however, which can not be classified with certainty with either.
Much the same phenomena are presented by the dikes. These
show considerable variation in thickness but are mostly under 30
feet and often only a foot or two. Some of them have their orig-
inal character in large part preserved, others are wholly changed
into amphibolite, yet others show intermediate stages. The
wholly changed dikes are so like other schistose, amphibolite
dikes which occur all over the Adirondack region that the writer
is not certain that they are not the same, though the ordinary
rusty appearance of the latter, coupled with the fact that they
have not been noted cutting any of the certain later eruptives
(anorthosites and syenites) disposes him to regard them as of
different and earlier age. Their mineralogy is precisely the same,
except that garnet is not so abundant as it usually is in the other
rock.
rE GEOLOGY OF FRANKLIN COUNTY ~~ EE
As far as can be judged from the less metamorphosed portions,
these gabbros show a similarity in mineral content and in struc-
ture which is unusual in gabbroic rocks. The essential original
minerals are in every case, a plagioclase feldspar (usually labra-
dorite), augite and magnetite (always titaniferous). In some of
the rocks hypersthene must be added to this list, but in these it
seldom equals the augite in amount, so that norite, an intrusive
rock constituted essentially of labradorite feldspar and hypers-
thene, is rare in Franklin county. In all cases in which the orig-
inal structure has been preserved, it is found to be ophitic, that
is the feldspar is in long, lath-shaped crystals separated by, and
partially embedded in, the large, stout prisms of the augite.
These primary feldspars and augites invariably hold a multitude
of minute, microscopic inclusions, the augite specially containing
them in such numbers that in thin section it would often be im-
possible to make out the color of the mineral, were it not for the
- fact that a narrow outer zone is comparatively free from them.
These inclusions in the augite are mainly opaque under high
powers and are probably of magnetite or ilmenite. The feldspar
inclusions are for the most part small augites arranged linearly
_ parallel to the long axis of the laths.
From the extinction angles shown by the feldspars in the
various slides it is quite certain that they show a range from
andesin to anorthite in the different specimens, with labradorite
the more usual one. The augite is of an exceedingly pale gray
green shade, nearly colorless in very thin sections.
In addition to the foregoing, even the least metamorphosed
-rocks show much rather finely granular material, either in clumps
or in trains, consisting mainly of garnet, augite, hypersthene or
bronzite, labradorite and hornblende, to which biotite is some-
times added. These are all in equi-dimensional grains, and were
forming at the same time, as none of them show crystal bound-
aries. In the more fully metamorphosed rock this granular ma-
terial increases till it comes to constitute the whole, all traces of
the original minerals having disappeared. In some slides the
large, original augites can be seen trailing out into this granular
112 NEW YORK STATE MUSEUM
“material, which has evidently been produced at their expense.
The feldspars occasionally show the same thing. It is however
in no sense a cataclastic structure, as the grains are not mere
shattered fragments of the larger crystals but consist of all the
minerals mentioned above. The process is one of recrystalliza-
tion and wholly owing to the metamorphism. In these granular
mixtures the augite, hypersthene and labradorite differ from the
primary minerals in being wholly free from the inclusions with
which they are packed.
In the main, recrystallization has commenced at the contacts
between the feldspar and augite, or feldspar and magnetite, and
such minerals as garnet which were not in the original rock have
resulted from the incorporation of material from each of the ad-
joining minerals. In several slides garnets of quite large size,
fully as large as any in the slide, are found as inclusions in the
primary feldspars, and at times augite and hypersthene are found
with them. In an unmetamorphosed rock their occurrence in
such situation -would be proof of their primary origin, as they
must have been formed before the feldspar in order to be so in-
cluded; but that can hardly be the case here, and the writer is
disposed to account for them in the same way as before, the augite
or magnetite necessary for their formation perhaps being fur-
nished by the inclusions of these minerals with which the feld-
spar is so heavily stocked. Often a narrow zone of the feldspar
around these included garnets has been completely freed from
these inclusions, which is corroborative evidence of the truth of
this explanation so far as it goes. It does not help to explain
why such inclusions of garnet are not more often met with, the
small ones being always present, but the same difficulty will apply
in a less degree to the entire rock, as garnet is by no means found
along all the contacts between the minerals concerned. Undoubt-
edly percolating water played a large part in the process, and the
garnet inclusions in the feldspars are always on the line of cleav--
age cracks. |
Two different varieties of hornblende occur in these rocks,
though never together so far as the writer’s experience goes.
GEOLOGY OF FRANKLIN COUNTY 113
While the one is the ordinary green brown hornblende of the
plutonic rocks, the other is a peculiar brown hornblende which
seems identical with that recently described by Van Horn in a
-hornblende-gabbro near Ivrea.t It has the same strong pleochro-
ism, a—faint yellow, b—reddish brown and c—orange-brown, with
absorption b> ¢ > a, and the other optical characters are in close
agreement. Like that also, it is associated with a green spinel
‘which is only found included in the hornblende.
The distribution of this mineral is peculiar. While it occurs —
to a slight extent in the granular material mingled with the
pyroxenes, garnet and feldspar which compose it, it has in the
‘main an exclusive tendency, occurring in bunches in which the
‘individuals are usually of larger size than the ordinary granular
material and have in part good crystal outlines. Sometimes they
are clustered around a magnetite crystal or crystals, sometimes
no magnetite appears in the cluster. In either case feldspar forms
their outer boundary. The phenomena are precisely such as char-
acterize what are known as reaction (or, better, as corrosion) rims.
‘The mineral seems to be of secondary origin in these gabbros and
to have been formed as a result of metamorphism from the inter-
action of feldspar and magnetite, or more rarely augite. A few
‘minute inclusions in the primary feldspars may be, themselves,
‘primary or have resulted from the same process that produced
the garnet inclusions. In the Ivrea rock, on the contrary, this
‘mineral is certainly primary, but it does not form corrosion rims
and holds the minute inclusions which are found in the other
‘primary minerals and which are lacking in the Adirondack
‘mineral. In the nests in which magnetite is lacking, it is judged
to have been there originally and to have been completely used
up in the process. 3
Most of the green hornblende is also secondary, but it makes
‘more show in the granular material than the brown does. The
latter is the usual hornblende in the bosses, the green in the dikes.
Where the metamorphism has been considerable, only the green
appears. Beyond question primary green hornblende oceurred
in some of these rocks, which must have originally been in part
1Van Horn, F. R. Tscher, Min. Petr. Mitt. band 17, heft 5.
114 _ NEW YORK STATP MUSEUM
hornblende-gabbros, but except for some few small inclusions in
the primary feldspars none of this original hornblende remains,
recrystallization having been much more complete in them than
in the ordinary gabbro.
In addition to the minerals already mentioned, apatite is always
‘present, often abundantly, in these rocks; titanite, pyrite and
pyrrhotite occur sporadically, and a little secondary quartz fre-
quently appears, mostly in close association with magnetite. In
the granular material a certain amount of the secondary feldspar
is usually without striation, and may therefore be ora
but no certainty in regard to this has been reached.
These gabbros as a whole belong to the type to which the name
of hyperite has been given by Térnebohm.
These rocks occur numerously in the county in the form of dikes:
cutting the anorthosites, and such show excellently in the many
rock cuts along the New York Central and Hudson River rail-
road between Saranac and Floodwood. As examples of the
bosses may be mentioned; 1) one by the road along the north.
branch of the Saranac 2 miles east of Hunter’s home, which is
fairly coarse, of the brown hornblende variety, and has a com-
paratively unchanged core; 2) another well shown in cuts along
the New York and Ottawa railroad between 14 and 2 miles above
St Regis Falls, also of the brown hornblende variety, which shows
beautifully the gradual passage of the hyperite into amphibolite
gneiss, the extreme phases of which are studded with very large
garnets mostly between 1 and 4 inches in diameter; 3) another
along the west shore at the head of Lower Saranac lake and run-
ning up on Boot Bay mountain, which is quite a large mass and:
correspondingly coarse; and 4) still another 2 miles northeast of
Vermontville, a curious little area inclosed by gneisses which are:
thought to belong to the augite syenites, in which both hyperite
and anorthosite gabbro occur with, as yet, unascertained rela-
tions to each other and to the inclosing rocks. :
Granite. There seem to be granites of two, possibly of three,
different ages in Franklin county. In considerable part they
have not been differentiated from one another.
GEOLOGY OF FRANKLIN COUNTY 115
In the northern part of the county, that part mapped as occu-
pied by the doubtful gneisses, there is a good deal of granite. No
very large masses have been noted, but there are several small
ones which send out tongues into the adjacent gneisses, and from
these a series of gradations into exposures showing the gneiss.
all eut up by small stringers of granite which run in general
parallel to the foliation; the phenomena being in short precisely
such as are common all over the world where these very old rocks
are exposed.
1 mile west of Duane postoffice and a few rods south of the road.
is a low cliff facing south, showing a rather fine grained, red
granite cutting amphibolite gneiss (see pl. 7). -The granite cuts:
vertically across the strike of the gneiss for the full hight of the
cliff (12 feet), incloses fragments of it and sends offshoots into it..
Like most of the granite of the county, it is essentially a quartz
feldspar rock, the amounts of magnetite, biotite and hornblende
being very insignificant. The feldspar is mainly microperthite,
but there is considerable microcline and a little oligoclase. The
rock is much metamorphosed.
The gneiss is essentially a plagioclase-hornblende-augite rock. 3
Extinction angles up to 20° indicate an acid labradorite as the
feldspar. The augite is not so abundant as the hornblende, but
in considerable amount, of green color with slight pleochroism.
The rock is not to be distinguished from :the gneissoid phases of’
the hyperite gabbros except for the absence of garnet, usually (not
always) abundant in the other rock. The age of the granite is
correspondingly uncertain, though of course it is younger than the
gneiss which it cuts. Just across the creek, 200 rods to the south-.
west, the same rock association appears.
- For a wide area around St Regis Falls and Dickinson Center
the prevailing rock is an amphibolite gneiss identical with that
‘Just described. Sometimes all pyroxene is lacking, sometimes:
hypersthene is present in place of augite. These gneisses are all.
cut up by granite which appears in small bosses or else in thin
bands in the excessively contorted gneisses. The granite varies
much in grain, being at times quite coarse, as at St Regis Falls.
116 NEW YORK STATE MUSEUM
in the river bed (see pl. 8). There are also bands of reddish ortho-
clase gneiss along with the dark amphibolite gneiss, which are
thought to be a part of the series and to have nothing to do with
the granite, though decisive evidence on this point is lacking.
Though no large masses of this granite have been discovered,
the total amount present is considerable. While clearly intrusive
in the gneiss and hence younger, it is thought to be much older
than the anorthosite, implying also that the amphibolite-gneiss
is older than the gabbro. The reasons for holding this view are
briefly as follows: |
1 The amphibolite gneiss is very widespread in Dickinson and
‘Waverly townships, and does not show massive cores, such as are
nearly always found in the hyperites, which are known to occur —
only in small masses or in dikes. Two such small masses
occur in the immediate vicinity, one to the south of the
falls along the railway and the other near the road less
than 2 miles west of the village, both with unchanged cores
and gneissoid periphery. While no contacts show, these outer
gneisses differ somewhat in appearance from the main body of
gneiss and are not at all involved with granite. The presence of |
granite, the more widespread character of the deposit and the
more complete metamorphism are the reasons for assuming the
older age of the amphibolite rather than ree it as identical
with the gabbro.
2 The granite occurs so suahnay and constantly cutting
these rocks that it seems incomprehensible that it should not be
found cutting the syenites and anorthosites to the south if it is
really younger than they. This association of this red granite
with amphibolite and also with orthoclase gneisses is constant
in the northern Adirondacks and must have some significance.
There are however later granites also. Those associated with
the syenites and distinguished by their coarse grain and spindle-
shaped quartz have been already described. In addition small
masses of granite have been found in a few places in the anortho- |
site, but unfortunately their precise nature is not clear. They re-_
semble the older granite, and some of them are unmistakable in-
YaWNVH AHL AAOUV LSA LSaa ONIMOHS LOVINOO GHL
‘ALINVUD HHL AX ASVA AHL LV LNO ‘LHDIU OL GNV UGLNGO NI SSIMND ‘LAT LY GALINVAD
‘MOMGOLSOd ONVNG JO LSHM AIIN [ ‘SSIEND ALIIOMIHAWVY LSNIVOV GLINVUY JO LOVLNOO GAILdnuyy
4 eld
Pe en
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art
GEOLOGY OF FRANKLIN COUNTY EGE:
clusions of small size caught up by the anorthosite from the in-
closing rocks. Others may either be dikes or somewhat larger
inclusions. In two cases the resemblance to dikes is strong, but
the exposures are not sufficiently extensive to furnish a demon-
stration, so that the matter must be left open for the present.
In addition to the above granites there are sometimes found,
cutting the anorthosites, curious dikes of a fairly acid rock with
_porphyritic feldspars and finely granular ground mass which re-
sembles somewhat some of the later syenite porphyry. The
ground mass is evenly granular and appears to have been com-
pletely recrystallized. These dikes have not been thoroughly
studied as yet, and are at present regarded somewhat doubtfully
as syenite dikes, whose slight width is accountable for their por-
phyritic character.
Diabase. Much later than all the foregoing are rocks which
make comparatively small showing in Franklin county. While
_ of several subordinate types, they may all be conveniently classed
as diabases, the distinction between them and the hyperites not
being a sharp one. They are said to be much later, since they are
not in the least metamorphosed, and have apparently solidified at
much less depth than any of the other eruptives; hence a long
intervening period of erosion is argued.
These are black, very fine grained, flinty rocks with conchoidal-
fracture and are very easy of recognition. They occur only in
dikes which range from a few inches up to 30 or 40 feet in width,
more commonly being from 1 to 10 feet, are nearly vertical, and
have an east and west trend, small offshoots only excepted. Near
the wall rocks cooling has been so rapid as to forbid much crystal-
lization, and the rock is glassy. The considerable variation in
grain from the sides to the center of these dikes, showing in all
but the exceedingly narrow ones, is one of their most distinctive
characters, and is in marked contrast to the even grain of the
hyperite dikes. They weather out into small, sharp-edged blocks
along planes produced by contraction on cooling. They are not.
likely to be confused with any of the other rocks except possibly
some of the hyperite dikes, but these last, in addition to their
118 NEW YORK STATE MUSEUM
evenness of grain, do not weather into blocks, are often schistose —
and usually show the red tinge due to the presence of garnet,
‘which seldom appears in the diabase.: |
An interesting feature of these dikes, which has been empha-
sized in previous reports, concerns their distribution. In Clinton
and Essex counties they are very numerous, so much so as to form
in places quite a respectable proportion of the whole rock mass. —
In Franklin and Hamilton they are much less abundant, and in
Franklin at least they are mostly in its eastern half. In the west-
ern Adirondacks they are practically absent.
They are also more abundant in the north than in the south-
east, more being found to the unit of area in Clinton than in ©
Essex. In other words, they are most concentrated toward the
northeast, so that the main center of the igneous activity must
have been in that region. Close to the Potsdam boundary in
‘Clinton they make a very impressive display. They may be even
more abundant beneath the cover of the later rocks to the north-
ward. ; |
Along with the diabases, though much fewer in number, are
complementary acid dikes which may be classed as a whole as
Syenite porphyries. These show the same center of activity
though not spreading so far away from it. They are practically
confined to Clinton county and are most abundant near the Pots-
dam boundary. They range from red to brownish black in color,
average wider than the diabase dikes and are more apt to con-
tain large, porphyritic crystals.
In Franklin county 37 dikes have been noted to date, though
these can be but a small proportion of the whole number. Their
situation is indicated on the accompanying map. Two are of
syenite porphyry, the only two dikes of this rock so far met with
in the whole Adirondack region outside of Clinton county. The
others are all diabases. Several of these hold bronzite, not a
common mineral in the Adirondack diabases which have hitherto |
been described. There are several types present, as already
stated, and they merit a more detailed description than they have
yet received. | 3 .
te ee ee
ee
MOVIIIA STIVA SIDUY LY {aLINVYD GHLNIOL-TTIGM UAAO UMAIU SIDAY LS wo S*ItVyT
8 48Id
GEOLOGY OF FRANKLIN COUNTY | 119
As nearly all the dikes have prophyritic feldspar, or augite or
both, they are strictly diabase porphyrites, and this is to be under-
stood in the table which immediately follows. In the large dikes
the porphyritic structure fades out in the center, with increasing
size of the ground mass constituents, the structure becoming
either ophitic or gabbroic. AJl the dikes show intersertal, or even
vitrophyric structure near the borders, according to the amount
of glass present.
Where the dikes have porphyritic structure, olivine is of the
first generation only, and is so to be understood in all olivine
diabase in the table.
NEW YORK STATE) MUSEUM
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GEOLOGY OF FRANKLIN COUNTY
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NEW YORK STATE MUSEUM
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GEOLOGY OF FRANKLIN COUNTY 125
Eruptive rocks of Silurian age. Igneous activity did not cease
in the Adirondack region with the close of the period of diabase
extrusion, but with a much later period of dike formation. The
eruptive center of this period seems to have been in New England,
and the dikes found in New York are practically limited to the
immediate shores of Lake Champlain. Kemp has described sev-
eral from Essex county, and the writer a few from Clinton. Both
acid and basic rocks occur, but in each case they differ somewhat
from the Precambrian eruptives in type, so that there should be
no difficulty, usually, in making determinations of age. No dikes
- which can be ascribed to this period have been found in Franklin
county, and the strong probability is that they do not occur.
PALEOZOIC ROCKS
Much later than all the previously described rocks of Franklin
county are the Potsdam sandstone, of Upper Cambrian age, and
the Calciferous dolomites and limestones, of Lower Silurian age,
which are found in the northern part of the county only. -The
overlying Chazy and Trenton limestones do not appear in the
county so far as known. These rocks have been briefly discussed
in a previous report, and no additional work has been done on
them.
These rocks were laid down on a much eroded floor of the older
rocks. Apparently the Adirondack region was a land area for a
larger part, if not the whole, of the long time interval between the
deposition of the Grenville series and of the Potsdam sandstone.
During this interval the amount of material eroded away from the
region was very great, apparently greater than the entire amount
removed since Silurian times, since which it has also been con-
tinuously above sea level. )
A single observation made far within the area occupied by the
Precambrian rocks, in 1897, is of considerable interest. An old
limekiln stands near the road running north from Alderbrook
postoffice to the north branch of the Saranac, somewhat over 2
miles from the former. Before visiting the place it was inferred
_1Cushing, H. P. 16th an. rep’t N. Y. state geologist. 1896. (geol. map)
p. 5-27.
124 NEW YORK STATE MUSEUM
that crystalline limestone of the Grenville series would be found
near at hand. However, no rock outcrops of any sort could be
found in the immediate vicinity, though occasional loose blocks
of Calciferous limestone were noticed lying about. Inquiry in
the neighborhood elicited the information that it was such that
_ had been burned in the kiln, that they were formerly there in great
abundance, and that no rock ledge had ever been worked to sup- .
ply the kiln.
Now except just here locally, Calciferous boulders are very
infrequent in the vicinity. The nearest outcrops of any paleozoic
rock are of the Hardscrabble Potsdam in Clinton county, nearly
15 miles away. The nearest Calciferous ledges are over 20 miles
distant in the same direction, that is to the northeast. ‘The writer
can account for the occurrence at the kiln only by supposing the
former existence there of a small outlier of Calciferous rocks, of
which the loose blocks represented the final trace. Many of the
limestones of the region weather out into a multitude of loose
blocks by more rapid solution of the rock along the joint planes
and by the subsequent disrupting action of frost, which raises and
tilts the blocks so that they lie loosely about, slanting in all
directions. This effect is shown beautifully in many places in
Clinton county where limestones are exposed, and where the
blocks are assuredly nearly in place, and yet wholly conceal the
ledges underneath.
If this be the true explanation, here the occurrence recalls the
Calciferous outlier at Schroon lake, Essex county, described first
by C. E. Hall-and more recently by Kemp, as well as similar and
larger areas in the southern Adirondack region! The limestone
may have been deposited directly on the Precambrian floor, that
is, it is beyond the limits of Potsdam deposition. If this be true,
important conclusions will follow as to the conditions of the dry
Jand area which would permit a limestone being deposited directly
on the old surface. But, as the occurrence is somewhat problem-
atic and may represent simply a small block along a fault plane,
1Hall, C. EH. 382d ann. rep’t N. Y. state mus. nat, hist. 1879. p.39.
Kemp, J. F. Bul. geol. soc. Amer. 1897. 8:411.
GEOLOGY OF FRANKLIN COUNTY 125.
it will not do to lay much emphasis on its possible bearing on the
question of the topographic character of the surface on which the
paleozoic rocks were deposited.
ECONOMIC GEOLOGY
The mineral deposits of the county which have been, are now,
or are ever likely to be of any economic value are the magnetic
iron ores, the Potsdam sandstone and perhaps some of the Pre-
cambrian rocks also as a source of building stone, the latter rocks.
for road metal, and the limestones as a source of lime. There is.
a possibility that brick clays may occur, though none have been
noted. From the standpoint of the present all these may be dis-
missed in a few words.
Iron ore. There are a great number of old ore pits in Franklin.
county, specially in Belmont, Duane and Franklin townships.
Emmons mentions ore worked near Saranac, in Santa Clara (town-
ship no. 11), several localities around Duane Center, and an open-
ing 4 miles west of Malone (probably on Gornish hill) That
represented the condition of the industry up to 1840, but in the
succeeding quarter of a century many more openings were made.
Emmons also notes that the ore is in different association from
most of the Essex and Clinton county ore, occurring in black am-
phibolite gneiss rather in the red, orthoclase gneiss full of titanite,
_ which is the usual rock in those counties. Emmons’s generaliza-
tion also holds good for the deposits opened since his report was
‘published.
_ None of these deposits were of very large size, none of them
have been worked this many a year, and there is no prospect that
any of them can be worked with profit in the immediate future.
It is only the unusually large and rich deposits, such as those at
Mineville and Lyon mountain, that can be worked with profit
under present conditions of the iron industry; and it is only the
recent rise in prices which has permitted work to be resumed at
Lyon mountain, the mines having been shut down for several years:
previous to 1898.
1Emmons, Ebenezer. Geology of New York. pt 2, p. 326-31.
-
126 NEW YORK STATE, MUSEUM
Large deposits of titaniferous magnetites in the anorthosites,
similar to those which supplied the ore for the old iron works at
Lake Sanford, in Essex county, are unknown in Franklin, though
such may occur. Iron ore is known to exist on the unnamed
mountain situated in the hilly tract to the north of Big Wolf pond
in Altamont township, but the locality is rather inaccessible, and
has not been visited by the writer, nor is the extent of the deposit
known. j
It is by no means impossible that similar deposits may be dis-
covered in township 27, on or about Mt Seward. This is one of
ithe wildest, most inaccessible, and least known tracts in the whole
A'dirondack region, and has never been exploited for iron so far
as the writer is aware. But, even if extensive deposits exist, they
would have but a prospective value, owing to the prejudice
against, and non-use of titaniferous ores in this country at the
present day.
Building stone. The only building stone quarries known to the
writer in Franklin county are all in the Potsdam sandstone and
mostly confined to the vicinity of Malone. These are all in the —
upper part of the formation, and quarry a white or buff stone of
fair to good quality which has mostly only a local use. The
lower, red beds, such as are quarried at Potsdam, make but small
show in outcrop in the county. At many places farmers have
made small openings in this formation for stone for their own
use. There must be an inexhaustible supply of good stone in
this formation, but outcrops are very infrequent considering the
extent of surface occupied by the rock, and no stone of the quality
and character of that quarried at Potsdam has been noted.
None of the Precambrian rocks of the county have been used
for building purposes, though some quarrying has been done in
anorthosite-gabbro at Keeseville and, more recently, on Rand hill
in Clinton. Nor is there likely to be any use of these rocks for
such purpose for a long time, except possibly an exceedingly re-
stricted local use. Yet there is a vast amount of good stone for
pbuilding and monumental purposes, the syenites, granites and
anorthosites all being capable of furnishing good material. ‘All
present phases which are very durable and take a fine polish.
GEOLOGY OF FRANKLIN COUNTY | 127
- Road metal. The roads in the county are mostly poor, many
very poor. In the northern portion the east and west roads are
on glacial deposits and are fair, but the north and south roads
-are largely in the vicinity of the streams, with their extensive sand
‘deposits, and are excessively sandy and poor. Back in the hills
the roads are usually not much traveled and are naturally not
well kept. But in places good roads have been constructed. Just
around Paul Smiths, specially on the road to the depot and thence
part way to Bloomingdale, recent great improvement has been
made by covering the surface with a layer of stone broken by a
rock-crusher, then covering with fine material and rolling with a
heavy steam roller. The rock used was obtained from the abund-
ant, loose boulders of crystalline rocks in the vicinity, some of
which serve excellently well and some not so well. But the whole
~makes a very good road and one that should stand for a long time
with the present moderate amount of travel, specially if kept in
good repair. The road from Tupper lake to Litchfield park and
those in the park itself are excellently made and though not
macadamized are carefully graded and covered with gravel.
_ These roads furnish good object lessons to the community, and
the most excellent rock materials for road construction occur all
over the county, so that it would nowhere be a matter of great
expense to obtain such. The larger diabase dikes, the gabbros
and much of the anorthosite and syenite furnish perhaps the best
material among the Precambrian rocks, either for a single course
of broken stone or for the upper layer of a Telford road. The
- more durable layers of the less quartzose gneisses would also ©
serve fairly well.
Some of the purer and firmer portions of the Calciferous forma-
tion would also furnish capital road material either singly or for
the lower course of a Telford road.
The Potsdam sandstone, which is used as a road material
around Potsdam, is wholly unfit for such purpose, as is almost
any sandstone, since it breaks down more or less rapidly to a pure
quartz sand, with the result that the last stage of the road is
‘worse than the first.
128 NEW YORK STATE MUSEUM
Lime. The writer does not know that any lime is burned in
Franklin county at the present day. In the old days the crystal-.
line limestone of the Grenville series was burned for lime, and
some of the old kilns are still standing. ‘The old kiln near Alder-
brook in which the Calciferous was burned has already been
mentioned. With the possible exception of some layers of the
Calciferous, these produce lime of very inferior quality compared:
with that obtained from the Black river and Chazy limestones:
along Lake Champlain, which are quite near at hand. The former:
use of the crystalline limestone as a flux has of course lapsed with.
the dying out of the iron industry. |
REPORT ON PROGRESS MADE, DURING 1898, IN
MAPPING THE CRYSTALLINE ROCKS OF THE
WESTERN ADIRONDACK REGION
Part 4
C. H. Smyts gr Puo.D. Ann D. H. Newuanp M.A.
\P
ty:
*
CRYSTALLINE ROCKS OF THE WESTERN ADIRONDACK
REGION
The field work for 1898 in the western Adirondacks was planned.
with reference to the desire of the late Dr James Hall, state
geologist, to issue during the present winter a new edition of the
geologic map of the state.
With this end in view, every effort was made to cover all of the
ground remaining unexamined, while the detailed study neces-
-gsary for a clear understanding and accurate delimitation of the
formations was almost wholly neglected.
The region studied embraces large areas in the central and
morthern parts of western Hamilton county, the northern third
of Herkimer county, and the southeastern corner of St Lawrence
county. These areas are practically all covered with dense forest,
the topography is rugged, and lines of travel few and difficult.
These, and other conditions, combine to make field work arduous,
and results unsatisfactory. A partial compensation is afforded by
the comparative uniformity of the rocks over wide areas.
After covering this part of the region, a hitherto unstudied
area in northwestern St Lawrence and northeastern Jefferson
counties was taken up. This area adjoins the region in which
most of the work of previous years has been done, and shows the
same complex geology. Yet in spite of this complexity, the writer
is convinced that this part of the crystalline area is by far the
most favorable for the solution of the problems afforded by the
gneisses, granites, syenites and crystalline limestones. But, as
already stated, no time was afforded for the study of these prob-
dems during the past season. The areal work was done under the —
writer’s direction by D. H. Newland, and, as no changes of classifi-
‘cation or nomenclature have been introduced, such formational
terms as are uSed in the present report are to be understood in the
same sense as in the two preceding reports. In the latter, it has
been pointed out how far from satisfactory and final these terms
132 NEW YORK STATE MUSEUM
are, but it has also, doubtless, been made equally clear that a
more definite meaning can be attached to them only as the result
of long and careful work.
As yet, not one of these formations has been accurately de-
limited over any wide area, in part on account of the perplexing
intermediate varieties which are so frequent, in part on account
of the absence of good base maps, but even more because the work
has necessarily been done very rapidly.
Under the most favorable conditions, the accurate mapping of —
the region must be attended with much difficulty; and the results
as yet obtained must be regarded as far from final.
This is particularly true of the gneisses, which are very complex
and troublesome. Some gneisses are igneous and some sediment-
ary in origin, without question, and it is probable that the former
class includes most of the gneisses of the region; but, at present,
it does not seem advisable to attempt any separation of the
gneisses, except to include in the limestone formation such as
appear certainly to be a constituent part of it. The gneiss, there-
fore, as represented on the map, must be regarded as by no means
a unit, though it is probable that a large proportion of it consti-
tutes a single formation, or at least is made up of rocks so closely
related in origin and age that they can not be separated. But
it surely comprises portions of the limestone formation, as well as
more or less modified later intrusive rocks, impossible to separate
except by close work.
The limestone formation is indicated only where the actual
limestone is present or some of the characteristic associated
‘schists appear, and therefore there can be no question that many
small areas of the formation are not represented.
The same may be said of gabbro, various basic gneisses which
may possibly be modified phases of this rock being included with
the gneiss. |
Granite and syenite are indicated only when the proximity of
limestone makes easy the determination of their intrusive nature.
Between the granites and syenites, on the one hand, and the
gneisses on the other, it is impossible to draw any sharp distinc-
MAPPING CRYSTALLINE ROCKS OF ADIRONDACK REGION 133
tion, as they are connected by every intermediate stage, and it is
clear that the former are massive phases of a part, at least, of the
eneissic complex. As, however, the age and origin of large areas
of the gneiss are as yet inferential, it seems advisable to indicate
the granites and syenites wherever possible, keeping constantly
in mind their close connection with the gneisses.
No attempt has been made to trace in detail the boundary be-
tween the crystalline and paleozoic rocks, and only incidental
data bearing on this point have been accumulated.
The work of the season has almost completed the reconnais-
sance of the western half of the Adirondack region. The extreme
southern part of Hamilton county and the adjacent part of Herki-
mer county have not yet been examined, and the same is true
of the vicinity of Black lake in St Lawrence county, and some
Other limited areas in the northern part of the region. As to the
first gap, that in Hamilton and Herkimer counties, it is practi-
cally certain that it is an area of gneiss with small limestone
patches. But in the north there is so much variation in the rocks
that decided changes may come in suddenly and unexpectedly.
To the southwest of Black lake, directly in the line of strike, lime-
stone, gneisses and granites occur in profusion, and, as* limestone
is known to occur on the shore of the lake, there can be no doubt
that, in a general way, this small area agrees with the region ex-
amined about Rossie and Redwood, but as to details nothing is
yet known.
From what has been said above, it is evident that the results of
ithe season’s work are chiefly areal. Nevertheless, in four partic-
ulars some light is shed on genetic andi structural problems.
In the last report it was shown that the hypothetic gabbro core
of the Adirondacks, with its narrow fringe of gneisses having
quaquaversal dip, has no existence, but, instead, that the region
consists chiefly of gneisses, cut by immense gabbro intrusions on
the east. Still, as there stated, it had not been shown that there
might not be areas of gabbro of some magnitude in the western
part of the region. This point is NOW settled; and it is clear that
an the entire western half of the Adirondack region gabbro occurs
134 NEW YORK STATH MUSEUM
only in scattered areas of small extent, wholly inadequate to ex-
ercise any influence on the general metamorphism of the region.
A second result of interest is the finding of frequent lumps and
lenses of hornblende gneiss scattered through the more acid
gneisses all over the region. ~- These masses are analogous to the
fragments described in the report for 1895 as probable inclusions
in an igneous gneiss. That they really are such now seems quite
certain, and they are regarded as affording most important evi- —
dence as to the origin of the gneisses.
A third phenomenon appears in the region about Longlake sta- —
tion, where a light red granitoid gneiss seems, without doubt, to
be intrusive in an older gray gneiss. This is directly in line with
facts observed near Gouverneur, St Lawrence county, also de-
scribed in the report for 1895, and, as there stated, shows that all
parts of the gneiss are not of the same age.
Finally, the red granitoid gneiss in the vicinity of Alexandria
Bay, on the St Lawrence river, was found to be younger than and
intrusive in the adjacent schists, which doubtless belong to the
limestone formation. This is analogous to many instances pre-
viously described in St Lawrence and Lewis counties, but is, if
anything, more clearly defined. It is important in affording
another example of an undoubted igneous gneiss, which in every
way closely resembles the great areas of gneiss farther south,
_ that are regarded as igneous, and yet, on account of the absence
of other formations, show no conclusive proof of their origin.
‘Furthermore, this Alexandria gneiss contains many hornblende
inclusions almost identical with the widespread hornblende
masses in the gneiss formation mentioned above. Final conclu-
sions as to the origin of these gneisses must be based chiefly om
analogy and internal evidence, such as composition and texture,
and every new occurrence of closely related rocks whose origin
is clear is a step toward the solution of the problem. |
This occurrence of intrusive gneiss at Alexandria Bay is also.
important in its bearing on the question of time relations. It.
has been generally assumed that either the gneiss and limestone
are one formation or that the gneiss is the older, the latter view
MAPPING CRYSTALLINE ROCKS OF ADIRONDACK REGION 135
being the more prevalent. But in the report for 1895 it was
shown that several large areas of gneiss are younger than the
limestone; and both in that and in the report for 1897 it was
stated that there is nothing to show that the limestone is not the
oldest formation of the region. Like the question of origin, that
of relative age must always be troublesome and, in many cases,
be answered only by indirect evidence; hence, again, the import-
ance of localities, like the one under consideration, where the
relation is evident.
; As already intimated, the general areal relations indicated in
_ the report for 1897 have been found to hold good for the entire
western half of the Adirondack region, gneisses being the pre-
dominant rock, with minor crystalline limestones, granites, gab-
bros, ete. .
In regard to the gneisses, one farther point demands particular
mention. In the last report much space was given to the dis-
cussion of the augite syenite of Diana and Pitcairn, and it was
shown to pass over into typical gneisses. Much evidence indi-
cates that the syenite gneiss is a widespread and important rock;
and Prof. Cushing has described! large areas in Franklin county.
In the field work of the past season it was found impossible to
separate this rock from other gneisses in the time available, and,
as previously said, it therefore is not distinguished on the map
except in the single type locality where its relations to the lime-
stone show its undoubted intrusive nature.
1Bul. geol. soc. Amer. 10:177-92.
PRELIMINARY REPORT ON THE GEOLOGY OF HAM-
ILTON, WARREN AND WASHINGTON COUNTIES
Part 5
By J. F. Kemp B.A. M.E., D. H. NpWLAND B.A. AND
B. F. Hitt M.A.
CONTENTS
PAGE
Letter of tranamitial .<.. a. ean ese eed Jaca 139
List of Dlustrations 222.065 2e6e- soci eae ot nooo as ce eee esas eee 140
Introduction—Outline of general results ....--. .-.--. -.-22. ------ wewece ones 141
Loeal geology by counties and Lonenia 9, 322s Ree ele or 141
Hamilton county 2.2 sco cece eee es oe eee ee eae ee ee er ~141
BengOn 25 os Se es Sse ees Gee Le oe Seow os cee ae ee 141
POPC 55 ta cnnie cat co car Sanam Sal een ce ee nee eb ee es pe et oe ee 142
WV Gls ea. hs aoe ane = aed See een Raa dea oes ees uel er 143
Lake Pleasant)... 122%. 2-2 sss en ne poe oe a en Seb ene eee 153
indian Lake ..c25. wo. ec! Sauk Senin cd seweee sepa eaeen ses eee ee 156
WV ATTEN COUDLY 4-7. - 50S e wots teu cds wont Seas eters See bua eee 157
POHUSVOTE 2k. bv. Seb mre See eae) elle aa pe Uo e pelbia ie ae oe ee 157
Washington county...) 22... escwe tens toed oboe ene eae ees eee ee 162
Port: Ann. Gos. sik tecekin deme Vansience a2 = Maehieee te owas eee eee - 162
FACING PAGE
Plate 1 Geologic map of Benson, Hope, Wells, Lake Pleasant and Indian
Lake ‘townships, Hamilton:00: 2. 52..4-<25¢.0028 .dances~ =e eaee 141
Plate 2 Geologic map of the vicinity of Wells village .................---- 144
Plate 3 Geologic map of Johnsburg, Warren co..-.-......- eka seeaee eee 158
Plate 4 Geologic map of Fort Ann, Washington co.....- 2 cae at eee aes 162
Dr Joun M. CLARKE
Sir: I submit herewith a report on the fieldwork performed
during the season of 1898 in the southern Adirondack region,
under my direction. The principal area lies in Hamilton and
ees counties near the border of the two, but some additional
observations were made in Washington county. The fieldwork
was chiefly done by David H. Newland B.A. and Benjamin F.
Hill M.A. The report and maps have been prepared by ,myself
on the basis of their notes, and in a part of the area I have made
some observations myself.
Very respectfully
- J. KF. Kump
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GNEISS ,CRYSTALLINE ANORTHOSITE GABBRO GLACIAL
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7 GmoLocic MAP oF BENSON, Hore, WELLS, LAK® PLEASANT AND InDIAW LAKE TOWNSHIPS, HAMILTON 00.
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INTRODUCTION—OUTLINE OF GENERAL RESULTS
The fieldwork for the accompanying report was performed in —
the summer of 1898. The observations on Johnsburg are the
work of Mr Newland; those on the townships in Hamilton county
were chiefly gathered by Mr Newland, who was assisted for a time
by Mr Hill; the data in Fort Ann, Washington co., were collected
chiefly by Mr Hill. Prof. Kemp has been over some of the areas
independently and has prepared the report and maps. The
present report extends to the westward and southward the obser-
vations of the previous season! The points of special interest
are the outlying areas of anorthosite in Johnsburg; the outlier
of paleozoic strata in Wells, which is here quite fully discussed;
and the increasing certainty of the existence of sedimentary
gneisses in Fort Ann and Johnsburg townships.
A general discussion of ithe provisional scheme of classification
adopted will be found in our previous report, just cited.
LOCAL GEOLOGY BY COUNTIES AND TOWNS
Hamilton county
Benson
Topography and geology. Benson is a mountainous and very
sparsely settled township in the southern part of the county and
lying just west of Hope. The two villages of Benson and Benson
Center are situated near the southern line, but north of these
there are almost no roads, and the country is quite inaccessible.
It forms the hight of land between the headwaters of West Stony
creek on the south and the west branch of the Sacandaga river
on the west, north and east. The latter rises in Silver lake, flows
south, then west, then north beyond the limits of our map, then
east through Wells township, and finally south through Hope.
Our explorations have been limited to the southern part of the
1Kemp, J. F. & Newland, D. H. 17tb an. rep’t N. Y. state geologist. 1897.
p. 499-553.
142 NEW YORK STATE MUSEUM
town, but from the general relations we think that gneisses make
up practically its entire area, unless there are some small lime-
stone outcrops or gabbros of which we have not learned. In the
drift a number of anorthosite boulders were observed, but none
of the rock in place. The prevailing gneiss is fairly massive, and
is often red from the large amount of red feldspar. The strike
is n 10 e magnetic, n 22 e true meridian, as observed near the
two Benson villages. Along the highway connecting these two
the gneiss is a crushed and: sheared augite syenite and is very
thinly laminated. It is dark green in color when fresh, but
weathers to arusty brown. The glacial drift is widespread in the
valleys. |
_ Hope
Topography. Hope is a small and sparsely settled township
in the southeastern corner of the county. Its surface is hilly,
and, while there are no elevations of very great altitude, ridges
_ almost entirely make it up. ‘There are two prominent valleys,
which are occupied respectively by the waters of the Sacandaga
river on the west, with a southwesterly course, and East Stony
creek on the east, with a southeasterly course. Even these val-
leys are narrow, being shut in by steep hills, and afford but a
slight foothold for agriculture. Highways of considerable im-
portance traverse them, the one along the Sacandaga being
specially used by summer visitors passing from Northville to
Piseco lake, Lake Pleasant and other resorts. Lakes are notably
deficient; only one small one is found, and that is in the northern
central part of the town. ee
Series 1. While the remoter and less accessible parts of the
town have received but slight attention, yet all the outcrops of
rock studied belonged to this series, and it is doubtful if any
except the glacial drift is met. If present, the other series would
be of small extent. The prevailing gneiss contains orthoclase or -
microperthite as its chief feldspar, and hornblende as the pre-
vailing dark silicate. Specimen 176 from the Sacandaga valley,
near the northern boundary of the town, exhibits in thin section,
orthoclase, microperthite, very little quartz, and a moderate
GEOLOGY OF HAMILTON, WARREN AND WASHINGTON COUNTIES 145
amount of green hornblende. This is syenitic in its nature, and
is like the Loon lake rocks of Franklin county and the rocks of
southern Benson. No. 176 is, however, greatly crushed and granu-.
lated. Along the Sacandaga valley in the southern part of the
town an augen-gneiss with biotite is quite extensively developed.
The general strike of the gneiss is n 35 w when referred to the
true north, and the dip is about 45 ne.
Series 6. In the valley of the Sacandaga the drift is largely
water-sorted and lies in terraces up to 40 or 50 feet above the
stream. Unsorted drift is also abundant throughout the town,
_ and its boulders embrace gneiss, gabbro and anorthosite.
Wells
Topography. Wells is a large, irregularly boot-shaped town-
ship, 20 miles long from north to south, and 15 miles wide ‘on
the south. The width on the north in the leg of the boot, is about
6 miles. The east branch of the Sacandaga runs southwest
across the southeastern corner, while the west branch flows east-
erly across the southern part. The surface of the township is
formed by a succession of extremely rugged hills, which are
closely set together. The average altitude is moderate but it
gradually increases to the north. Both the east and west
branches of the Sacandaga are swift streams, till they unite,
and then the descent is more gradual and the current less swift.
A number of ponds occur throughout the town, but none are
specially large. The valleys are as a rule narrow and are inclosed
between steep walls. Except the west branch of the Sacandaga,
practically all the streams flow southwest, following the general
trend of the valleys.
Geology. Special interest attaches to the geology of Wells on
account of the outlier of Cambrian and Lower Silurian strata that
is found near the village of Wells, and which will be fully dis-
cussed later. In addition, the other five series of formations,
under which the rocks have been customarily grouped in our
descriptions, are present, except no. 5, which embraces the trap
_ dikes. The latter may be present, as our explorations have been
144 NEW YORK STATE MUSEUM - A
incomplete in some parts of the town, though general experience
so far as hitherto gained, has indicated a decrease, if not a failure,
of dikes in the southern central and southwestern crystalline areas.
Series 1. Gneisses. The rocks of this series are much the
most important of all and constitute almost the entire area.
Several different varieties of gneisses are recognizable. The most
widespread is one typified by specimen 179, from the hills to the’
west of Wells village. It is a rock that is greenish when fresh
but red when weathered. The chief minerals are biotite, ortho-
clase, quartz and plagioclase. Garnet is abundant, and pegmatite
streaks run through the outcrops. This particular rock bears
witness to fairly severe dynamic metamorphism, but others have
suffered much more and still others less. No. 170 is a granite not
very badly crushed, while 169 and 172 are of the same general —
composition but are rolled out into thin layers. No. 174 al-
most if not quite approximates a schist, and under the micro-
scope displays biotite, quartz, plagioclase, orthoclase and garnet,
granitic gneiss, and must lie along some old fault line or line of
crushing. No. 176 is a syenitic gneiss, and under the microscope
exhibits orthoclase, microperthite, strained plagioclase and horn-
blende. No. 220 just on the ridge northeast of Wells village is the
same.
In the hornblendic gneisses are bands of nearly pure horn-
blende, which may contain pyrite. These bands may be several
feet thick. One of exceptional persistence is exposed at locality
178. They are always parallel to the foliation both in dip and
strike, and, if they are sheared trap dikes, the foliation has been
induced in a direction parallel to the original strike of the dike.
The strike of the gneisses is prevailingly northwest and south-
east, but it shifts occasionally even to a bearing at right angles
with this. Changes in the direction of the dip are also often
observed.
The gneisses are extensively jointed, and often exhibit emphatic
escarpments along the line of the major joints; still it is not easy ~
to discriminate these steep cliffs from fault scarps. Just to the
northeast of Wells village the joints run n 80 e and n 15 e true
bearing, and the former gives rise to cliffs and ledges.
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tica Drift.
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GEOLOGIC MAP OF THE VICINITY OF WELLS VILLAGE, HAMILTON Co.
GEOLOGY OF HAMILTON, WARREN AND WASHINGTON COUNTIES 145
Series 2. The crystalline limestones and their associates are
represented in two areas, respectively northeast and cast of the
village of Wells. The former yielded specimen 167, and is an
extremely impure variety. The rock is so charged with pyroxene,
quartz, feldspar and graphite as to have but a comparatively
small amount of calcite. No. 222, from the latter locality, is very
richly speckled with pyroxene, but some streaks of fairly pure,
coarsely crystalline marble were recorded. Pegmatite, however,
and quartz were associated with it. Both these small outcrops
were inclosed in gneisses and ran parallel to the foliation.
Series 3. A single gabbro intrusion has been observed at 221,
due east of Wells village. The gabbro is of the usual basic type
found in the Adirondacks, and is faintly foliated from pressure.
Boulders in the drift suggested the possibility of the presence of
anorthosite in the northeastern part of the town, over toward the
known areas of this rock in Johnsburg, west of Thirteenth lake.
None were however observed in place, and this section is not very
accessible.
Series 4. The small remnant of paleozoic strata near Wells
furnishes the special point of interest in the local geology. The
remnant presents the most complete section of any of the paleo-
zoic outliers in the midst of the crystalline rocks. Several of
these are now known, viz, near North River, Warren co.;
near Putnam pond, Ticonderoga, Essex ¢co.; Trout brook, near
Lake George, Ticonderoga!; North Hudson, Essex co.; several
in Crownpoint, Essex co.; and Schroon Lake postoffice, Schroon,
Essex co. The last named is Calciferous, all the rest are Pots-
dam. There is excellent reason to think that another exists near
Elizabethtown, Essex co., but only loose slabs of Potsdam have
as yet been found. At Wells the Utica, Trenton, Calciferous and
Potsdam beds have all been recognized, but the Chazy fails as is
- usual toward the south side of the mountains. The four strata
present are each of very limited extent. The nearest outcrop of
1For a review of those in Ticonderoga, see Kemp, J. F. Physiegraphy of the
Eastern Adirondacks in the Cambrian and Ordovician periods. Bul. geol. soc.
Amer. 8:408. See also 15th an. rep’t N. Y. state geologist. 1895. p.596. The
North River, North Hudson and Elizabethtown cases have not yet been described
in print.
~
146 NEW YORK STATE MUSEUM
related paleozoics is at Northville, about 13 miles to the south,
where the Potsdam appears, and near which the Calciferous is:
known. The Trenton is met about 5 miles still farther south,
and the Utica a few miles beyond. This outlier is therefore not
so isolated as the Schroon lake exposure, which is 15 miles west
and 40 miles north of the nearest related outcrops; and the North
River exposure is even more remote from its own kind.
The exposures at Wells were first recorded by Ebenezer Emmons,
so far as the writer (J. F. K.) can discover. In the Geology of the
second district, p.417, he says, while speaking of Hamilton county:
“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. They form the extreme point of the Champlain group,
which comes up from the Mohawk valley through Northampton
and Mayfield.” Though Prof. Emmons said Hope, he must have
meant Wells, as no outcrops occur at Hope. Prof. Hall has stated
to the writer that Vanuxem first discovered the Wells exposures, -
in 1842, and this statement has been repeated by Darton, the
writer, and Ruedemann, but Vanuxem’s report on the third dis- —
trict makes no mention of the Wells outcrop, while Emmons does
in 1842, as above quoted. Hamilton county belonged in the see-
ond district. Darton’ gives some data regarding Wells and a
geologic cross-section, which is however somewhat assumed, as
a comparison with the detailed map here given will show. Mr
Darton had the large faults in mind, that run north and south,
and the details at Wells were somewhat incidental to a larger
theme: Rudolf Ruedemann has also given considerable attention
to the Wells area in connection with his extremely significant and
interesting observations on the directions assumed by the grap-
tolites in the Utica slates, which give a ‘clue to the currents of
the Ordovican sea.27 Dr Ruedemann describes the Wells outlier
‘as forming an oblong plain on whose sides the walls of gneiss rise
1Darton, N. H., 13th an. rep’t N. Y. state geologist. 1893. p.415. Idem. 1896.
p. 47.
2Ruedemann, Rudolf. Evidence of current action in the Ordovician of New
York. American geologist. June 1897. In this paper Wells or Wellstown, is.
merely referred to on the map. Additional note on the oceanic current in the
Utica epoch. Idem. February 1898. p. 75.
GEOLOGY OF HAMILTON, WARREN AND WASHINGTON COUNTIES 147
in fault scarps, so that the valley is a depression dropped by fault-
- ing below the general level, i. e. it is one of the “ Graben ” as the
term is used abroad. This appears to be certainly true for the
west side of the valley, where the gneisses go up in a fairly steep
wall, but it is less evident, though quite probable, for the east
side. Dr Ruedemann develops an argument against the concep-
tion set forth by the writer in the “Physiography of the Adiron-
dacks in the Cambrian and Ordovician periods” (cited above), that
the early paleozoic sediments set up into embayments and sub-
“merged valleys in the subsiding archaean land area. The argu-
ment is based on the general similarity of the paleozoic beds at
Wells to those of the main areas along the south side of the moun-
tains; and on the general parallelism of the positions of the Wells
graptolites as they lie in the slates, to those in the Utica beds to
the south. Dr Ruedemann therefore infers a general mantle of
the paleozoics over the crystallines and their preservation in this
outlier by infaulting. As preliminary to farther discussion of
this point, details of the Wells exposures will now be given.
Potsdam sandstone. The Potsdam appears in largest ex-
posure just east of the Catholic church, but it is also revealed in a
pit, about 8 to 10 feet deep, immediately east of the hotel. At the
former locality 6 feet of thickness is exposed, but more lies below,
so that a total of at least 30 to 35 feet was inferred. The rock is a
tine grained, cream colored sandstone, rather thickly bedded, and
shows occasional tendencies toward conglomerate. Ripple-marks
are present. Under the microscope it appears as a quite pure
quartz sand, with grains about ;; of an inch in diameter (5
mm). The grains are all rounded in a very noticeable degree,
and they must have been well triturated before deposition. They
are the common variety of quartz, as found: in the ancient crystal-
lines. A little kaolinized and somewhat iron-stained feldspathic
material is also present. |
The exposure back of the hotel is very limited in extent, and
merely presents a fine, even grained and rather heavily bedded
sandstone, of whose thickness we have no means of knowing. Its
chief interest lies in the fact that it is flat and about 30’ below the
148 NEW YORK STATHD MUSEUM
‘Calciferous limestone to the east, which doubtless rests on it,
though the intervening connection is concealed by drift.
Calciferous. The Calciferous is exposed in only one place,
‘which lies east of the hotel and stretches for some distance along
the road leading northeast from the Roman catholic church. It
is a non-fossiliferous, silicious limestone with nodules of white -
calcite. Cherty streaks were also observed. The limestone has
-a very slight inclination to the west. The thickness of the forma-
tion could not be determined, but in a brook valley, near its east-
ern limit, several feet were exposed, so that from the general rela-
‘tions a thickness of about 30 feet was estimated.
Under the microscope the limestone appears as a rather fine
‘grained aggregate of dolomite crystals of about .01 of an inch
(.2 mm) on the average, and quite richly set with rounded, water-
‘worn grains of quartz, two or three times the diameter of the
‘dolomites. In a slide from an outcrop about 100 rods east of the
hotel the quartz grains make up one third the material. There
-are also round areas that suggest organisms, but no definite struc-
ture could be made out. Evidently the original of the dolomite,
probably a limestone, was exposed to the sweep of rather swift
currents and the incursion of moderately coarse sediment.
Trenton. The Trenton is in many respects the most interest-
ing and significant of all the paleozoic exposures. It is a lime-
‘stone that varies from light gray to almost black. It occurs in
two places. The southern exposure, which lies on the west bank
of the river, due west from the Catholic church, consists of loose
‘boulders, which are not positively in place, but which are thought
to be on the spot of the parent ledges. Comparatively little at-
tention has therefore been given by us to this locality. The ex-
posure of chief interest lies north of the Lake Pleasant (or Sage.
ville) road and comprises a number of loose blocks and one large
ledge that is certainly in place. The latter has received our
special attention, and from it the material here noted was derived.
‘The ledge is about 60 feet long, 30 feet wide, and 10 feet thick.
‘Over the large blocks grassy hummocks of rectangular shape have
eee Mes ee ee 7 Ts,
GEOLOGY OF HAMILTON, WARREN AND WASHINGTON COUNTIES 14%
formed. The following section was measured in the large block
above referred to. The strike is n 57 e, dip 7 w, true meridian.
No.5 2 feet of rather thinly bedded, fine, black limestone, with
abundant fossils.
No. 4 2 feet 6 inches of heavily bedded limestone rich in fossils.
The grain is finer than no. 3, and abundant quartz grains.
occur through the rock.
No.3 8 feet 6 inches of hard, coarse limestone, in 8 layers.
No. 2 6 inches to 14 inches of loosely textured, shattered lime-
stone; white where weathered but dark inside; finely
erystalline.
No.1 1 foot hard limestone with abundant brachiopods, but not
well preserved.
A number of fossils have been gathered from these ledges, which
have been kindly determined for us by Gilbert Van Ingen, as:
. follows:
No. 5 Hormospira alexandra Billings
Illaenus sp.
Cyrtoceras
Orthoceras cf. trochleare Hall, 1847
Strophomena incurvata Shepard
Crinoid, columnar plates
No. 4 Fragmentary fossils abundant but not adapted to sharp
determination. Crinoid stems, brachiopods, trilobites and corals
all recognizable. Illaenus sp. was the only one generically
recognized. This layer also contains sand and pebbles of
quartzite and gneiss, up to 3 to 4 inches in diameter, to which
reference will be made below.
No. 3 This is the most productive layer, and its fossils are well
preserved.
Strophomena incurvata Shepard
Plectambonites sericeus Sowerby
Isotetus gigas Dekay
Dalmanella testudinaria Dalman
Ceraurus pleurexanthemus Green
150 NEW YORK STATE MUSEUM
Rhynchotrema inequivalve Castelnaw
Parastrophia hemiplicata Hall hag hae
Hormospira alexandra Billings .
Liospira americana Billings
Murchisonia ??
Sponge ae
No. 2 Strophomena incurvata Shepard
Parastrophia hemiplicata Hall
No.1 Strophomena incurvata Shepard
Mr Van Ingen regards the fauna as being that of the lower part
of the Trenton as found in the Champlain valley.
Layer no. 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.
A little plagioclase feldspar is present, and one zircon was de-
tected. In size the fragments range from .1 mm up to 15 mm
(.004 to .5 inches). Definite iron-bearing silicates are lacking, but
one magnetite fragment was observed. Thin sections were cut
of two pebbles of the erystalline rock. Each was found to contain
quartz and kaolinized microperthite in about equal amounts, and
to have many pyrites disseminated through it. The pyrite was
jin part altered to limonite. The pebbles were certainly derived
from the ancient crystallines and are pyritous quartzites or
gneisses such as accompany the crystalline limestones. One
pebble of a very fine limestone was also examined microscopically,
but showed nothing unusual.
Utica slate. The Utica appears in three small separate ex-
posures, lying on the west side of the river. The northern one
is the largest and best, being 100 feet long, and 13 feet thick.
The slaty cleavage strikes n 52 e, 15 n w, referred to the true
north. Bedding is not apparent. In the two southern localities -
only a foot or two of weathered slate was exposed. The large
outcrop was divided into five sections, of which the upper was 3
feet, the other four 2 feet each, and the fossils from each were —
~ ‘
GEOLOGY OF HAMILTON, WARREN AND WASHINGTON COUNTIES 151
kept separate. They have been identified as follows by Mr Van
Ingen:
No. 5 3 feet. Ostracoda, abundant
Turrilepas canadensis Woodward
No. 4 2 feet. Lamellibranch
No. 3 2 feet. Small Ostracoda in abundance
- No. 2 2 feet. Calymmene senaria Conrad
No. 1. Indistinct Lamellibranch
Calymmene senaria Conrad
No graptolites were found by us, but Dr Ruedemann mentions
Diplograptus foliaceus Murch. (—pristis Hall) and
also fragments of Endoceras, and casts probably of
Modiolop sis. He regards the rock as lower Utica.
The dips of all the beds are so low as to be with difficulty de-
termined. A reading for the Potsdam was obtained of 3° to 4°n.
The Calciferous dips slightly to the west. The Trenton strikes
n 57 e and dips 7 n w when corrected for magnetic vari-
ation. In the Utica a supposed cleavage gave a reading n
52 e, 15 n w. It is evident from this that the dips are to the
northwest, and that with the faulting there has been a slight tilt-
ing in this direction. At the same time it is surprisingly small,
and the blocks must have dropped very easily. It is a specula-
tive question as to whether the several blocks of paleozoics are
themselves faulted with regard to each other. They either are, —
which we doubt, or else the cross-section of each is very small,
and we must infer that the several formations have thinned
greatly in this area, from their normal magnitude. The uncer-
tainty of these relations is the reason for not drawing a cross-
section.
In the interpretation of the deposits, the presence of the lime-
stones would indicate that the estuary if present, in accordance
with the views advanced for the Champlain side, must have been
a very broad one; and we are quite free to admit that the present
walls of the valley are fault-scarps. There is no question of this;
but that a land area existed to the north and at no great distance,
we think is equally assured. The Potsdam is a shore deposit, and
-
152 NEW YORK STATE MUSEUM
its characters indicate a beach sand. The Calciferous, though &
limestone, must have been within reach of relatively swift cur-
rents charged with moderately coarse sand. The sand is general
throughout the bed that contains it and is not in layers. It was
afforded with some uniformity. In the Trenton times conditions.
evidently varied. Up through layer 3, sedimentation quietly and
uniformly progressed, but at the time layer 4 was deposited there
was an influx of sand and water-worn pebbles of large size, which
are now mixed with rounded fragments of fossils and limestone.
The sand is quite uniformly distributed through the rock, for
some thickness. The pebbles and the sand were derived from the
neighboring crystallines, and may have been mixed up with the:
lime by floating ice. The fact that the pebbles are of gneiss:
materially modifies the conclusions of Dr Ruedemann. as set forth,
on page 78 of his paper (Amer. geol. 1898) in the discussion
on the conglomerates in the Trenton, for he only knew of
limestone pebbles at the time. They appear to us to demonstrate
neighboring land areas of the archaean. While therefore the
paleozoic sea evidently encroached on the ancient crystalline
area, and may indeed at one stage have gone entirely over it, yet
in the Trenton it did not cover it, and it is reasonable to suppose
that, as the sea encroached in the Potsdam and Ordovician times,
it set up estuaries. It is, however, certain that the walls of the
Sacandaga valley are not the boundaries of the ancient estuary, if
such existed.
Series 6. The glacial deposits are widespread in the town. On
the hills they are morainal, and often contain large boulders.
Gneiss, gabbro and anorthosite are the chief rocks present. In
the valleys, water-sorted sands and gravels are the rule and near
Wells the latter form pronounced terraces. Near specimen 178,
to the southwest of Wells village, glacial striae were observed
on the hornblendic gneiss which there outcrops. Their direction
is n 40 e magnetic, or n 52 e when referred to the true north.
This corresponds with the general experience in eastern Hamil-
ton county. Boulders of Potsdam were noted near by.
GEOLOGY OF HAMILTON, WARREN AND WASHINGTON COUNTIES 153
Lake Pleasant
Topography. Lake Pleasant is a long and relatively narrow
township, lying north and west from Wells, and southwest from
Indian Lake. It is one of the largest townships in the county,
being some 25 miles from north to south and about 8 miles from
east to west. The southern third of the town is largely occupied
by a broad valley containing Lake Pleasant, Sacandaga lake,
Fawn lake, Hamilton lake, and running westward into Arietta
township, with Oxbow lake on the border and Piseco lake just
over the line. In this valley most of the population is located.
The village of Lake Pleasant is the county seat, and Speculator,
formerly called Newton Corners, is another hamlet. Each con-
tain a few hundred people, but are popular resorts during the
summer months. Fawn, Oxbow and Piseco lakes drain off to
the southwest into the west branch of the Sacandaga, while
Lake Pleasant and Sacandaga lake discharge to the north into
the Jessup river and so out to Indian lake and the Indian river.
The genera] elevation of this portion is moderate, ranging about
1700 feet A. T., and the hills are of comparatively slight altitude.
Speculator mountain on the east side of Lake Pleasant attains
2500 feet and is the most prominent summit of all. It is quite
possible that the open character of this area is in part due to the
presence of crystalline limestones, of which we have found con-
siderable outcrops.
As one goes north, however, the country becomes more rugged,
and the higher summits attain notable altitudes. Dry mountain,
in the central part of the town, is 3260 feet above tide, and
other neighboring peaks are but little less. Still farther north
the mountains reach higher levels. The Blue Ridge is 3865;
Lewey, 3740; Cedar, 3402; two unnamed peaks attain 3723 and
3685, as shown by the Indian Lake sheet of the United States
geological survey. All these peaks lie along large ridges, whose
trend is markedly northeast and southwest, and the lakes and
streams likewise have this genera] direction. As a rule the
ridges are separated by narrow valleys but in the case of the
Lewey lake—Indian lake depression and the Cedar river flow,
154 NEW YORK STATE MUSEUM |
they are broader and more pronounced. Lewey lake is 1651
above tide and the Cedar river is 2100. 3
Our explorations have been chiefly limited to the southern and
central parts of the township. The extreme northwest has not
been visited, but, aside from possible limestone and gabbro areas,
there is every reason to expect the usual gneissoid rocks. No
recorded work has been done very near this point to the west,
but the gneisses met by Prof. C. H. Smyth jr at Honnedaga lake
and the gneisses with gabbros near Wilmurt lake would give
ground for expecting these types.
Series 1. The gneisses are much the most important rocks in
the township, and they present among themselves considerable —
variety. In the field the greater part was collected as hornblen- —
dic gneiss. No. 158 has, for example, the aspect of a reddish, ;
hornblendic granite. Nos. 157 and 159 are greatly squeezed, horn-_-
blendic varieties, rusty on exposure, but darker and darker green.
as one breaks into the fresh interior. They show comparatively
little quartz to the eye, but appear to be rather syenitic in their
composition. No. 150 is a dark green and apparently somewhat
basic rock, but, when it is examined under the microscope, abun-
dant quartz is seen: The other minerals are orthoclase, plagio-
clase, colorless augite, brown hornblende, and feebly pleochroic,
orthorhombic pyroxene. It is a pyroxene-granite and is very
badly crushed and sheared. No. 156 is the same variety of rock
as 163a. No. 162 appears to be a very finely crushed pegmatite
or haplite, if indeed it is not a metamorphosed feldspathic sand-
stone. Dark silicates are very few, though some scales of musco-
vite are visible. No. 164 is a greatly crushed and granulated
aggregate of quartz, microperthite, plagioclase, orthoclase, and
biotite. No. 165 is a fairly massive, hornblende granite or
related rock.
So far as examined with the microscope, all these rocks show
the effects of severe crushing and have evidently undergone ex-
tensive dynamic metamorphism. Foliation is never lacking,
though in some it is more pronounced than in others. The strike
of the foliation is somewhat variable, but it is rather more often
GEOLOGY OF HAMILTON, WARREN AND WASHINGTON COUNTIES 155:
‘northwest than otherwise. This trend is pronounced in the north-
ern part of the township. In the southern part, near and west
of Speculator and near the limestone areas, it is quite variable.
‘The dips are prevailingly southwest and as a rule are flat. But
many cases of uncertain dips arise, and in these no record could
be obtained.
Series 2. Two areas of crystalline limestones and associated
rocks have been met. The larger begins a short distance north-
west of Speculator and extends 2 miles along the road to Lewey
lake. It involves outcrops of crystalline limestone and the pecu-
liar types of rock that are often associated with it. No. 154 is.
limestone, with a little coccolite and some graphite. It appears.
in a ledge with pyroxenic rock, and varieties resembling quartz-
ites. The limestone extends about half a mile along the highway
to the northwest and changes gradually into a more and more
silicious variety, which finally becomes a rusty rock represented
by no. 155. Under the microscope it is found to be chiefly a clear,
colorless pyroxene, with scales of graphite and irregular bits of
pyrrhotite and titanite. This pyroxene is a rather characteristic
associate of the limestones, and will be mentioned again in con-
nection with 153. Specimen 152 is a green rock full of pyrrhotite.
In connection with the varieties mentioned there is also a notable
development of pegmatites, such as are habitually seen near the
limestone areas. Bands of pyrrhotite-gneiss like 152 appear quite
frequently, and, while the usual gneisses are present, the former
leave a strong impression of being metamorphosed sediments.
These peculiar rocks, characteristic of the limestone series, also
extend along the road to Whittaker (or Wallula) lake, and they
may cover more area than we give them on the map.
The second exposure was found along the road northeast from
Speculator toward Elm lake. Only small outcrops of limestones.
were seen, but specimen 153 is a graphitic, gneissoid rock, or
quartzite, and would therefore appear also to belong to this series.
Under the microscope it exhibits quartz, colorless pyroxene, yel-
lowish phlogopite, zircons and graphite. Apparently it must
have been a somewhat calcareous sandstone or shale before meta-
156 NEW YORK STATE MUSEUM
morphism and must have contained some bituminous matter
which yielded the graphite. |
In the large area of series 2, the strike so far as recorded is
northeast, but at opposite ends of the exposures the dips are
opposed to each other. We have, however, too few data at hand
to justify conclusions as to structure. Contrary to the usual
experience this area of the limestone series is on the hills instead
of being in the valleys.
Series 3, 4 and 5. No anorthosites or gabbros, no paleozoic
strata and no trap dikes have thus far been discovered.
Series 6. Glacial sands and gravels are found in heavy deposits
throughout the Lake Pleasant valley, but are thin or wanting
on the higher elevations to the north. Glacial striae were found
northeast of Speculator, with a northeasterly bearing, just as in
Wells. is
Indian Lake :
The northern part of Indian Lake was covered in our report
for 1897. The southern part is alone taken up at this time. .
Topography. The southern part of Indian Lake township con-
sists of three pronounced northeast and southwest ridges with
two deeply incised valleys between them. In the southeastern
one lies Indian lake, about 7 miles in length—with a maximum
width of half a mile. This is the size recently produced by raising
the old dam that formerly existed at its lower end, so that an old
overflow was included in the lake. It is planned to raise it still
farther, so that it will set back into Lewey lake. The present
altitude of Indian lake is 1626. From its shores the mountains
rise steeply, reaching on the east about 2500 feet as a maximum,
but on the west, in Snowy mountain, a maximum of 3903. The
valley of Squaw brook, a steep and narrow depression, then inter-
venes, and on its western sides the peaks range from 3500 to
almost 4000 feet. All this part is wild and not easily accessible.
Snowy mountain is the highest in the Adirondacks outside of
Essex and Franklin counties. :
Indian Lake township is very sparsely settied. A few houses
are found along the highway from North creek to Blue mountain
GEOLOGY OF HAMILTON, WARREN AND WASHINGTON COUNTIES 157 *
lake, which latter is a popular summer resort, but aside from this.
the town is practically a wilderness. The geologic exploration.
is still quite fragmentary, but, adding to last year’s report the
observations of 1898, a general idea may be formed of its leading
features. The present notes are chiefly based on a trip from
Lewey lake through Indian lake, with detours inio the mountains.
lying on each side.
Series 1. Gneisses make up almost the entire area. Last sea-
son’s work showed that a quartz-hornblende variety was the
chief one in the northern part of the area. The 1898 work has
brought to light in specimens 160 and 161 gneisses like 150 of
Lake Pleasant. They have the mineralogic composition of
pyroxene-granite. They are strongly foliated and present glisten-
ing cleavage faces on the feldspars that are characteristic of this.
variety of rock.
A strike in each of these cases was noted, bearing to the north-
west, which is impressive because it crosses the trend of the
ranges. The dip was low to the south.
Series 2. A small area of crystalline limestones and associated
rocks was noted in last year’s report from the eastern town line,
on the North creek road.
Series 3, 4 and 5. No gabbros, anorthosites, paleozoics or trap
dikes have as yet been discovered.
Series 6. The glacial deposits surround Indian lake and are
present in the valleys and on the broader or lower hills. The
higher summits are, however, quite bare. Glacial striae noted in
1897 near Blue mountain lake bear a little east of north and are
therefore more northerly than those of Lake Pleasant and Wells,
Warren county
Johnsburg
Topography. Johnsburg is the largest township of Warren:
county and lies in its extreme northwestern corner. Over the
greater part of the area the township is very sparsely settled, the
farms occurring chiefly along or near the Hudson river, or on the
highway which runs across the southwestern corner to Wells
in Hamilton county, and which passes through the hamlets of
‘
158 NEW YORK STATE MUSEUM
Bakers Mills and Oregon. Johnsburg village lies about three
miles west of the Hudson in the eastern central part of the town.
Northcreek, the present terminus of the Adirondack railway,
and North River, 5 miles up stream, are in the extreme northeast
corner. Several small villages are also situated in the eastern
part. :
The Hudson forms the eastern boundary and flows in a valley,
_which is shut in by low hills. Passing westward across Johns-
burg, one meets with hills of moderate elevation and of rather ©
easy Slopes, except for Huckleberry and Crane mountains on the
south, respectively 2441 and 3245 feet above tide, and Gore moun-
tain on the north, a huge mass, 3594 feet high. In the southwest
the topography becomes again extremely rugged. The Sacandaga
river and its tributary, the east branch, have cut their way
through narrow passes in this portion, and, though the latter
rises on the west slopes of Gore mountain, within 5 miles of the
Hudson, its waters flow more than 50 miles before they enter it. —
In the southwest the mountains almost reach 3000 feet, the Blue ~
hills attaining 2938, but farther north and nearly in the middle
of the town Eleventh mountain is 3303. The northwest corner
of the town is also very rugged and mountainous, Puffer moun-
tain being 3480 and Bullhead 3455. In a narrow valley lies Thir-
teenth lake, a fine body of water, 2 miles long and 1674 feet above
tide. All the drainage of the township passes into the Hudson,
though the streams in the southwestern part do so through the ~
Sacandaga by a very circuitous course.
Geology. ‘Much the greater part of the town consists of the
gneisses of series 1. The crystalline limestones are however
present in important exposures, which throw much light on their
general stratigraphic relations. The anorthosites and gabbros
have also been found in quite extended areas, and one small but
interesting outlier of Potsdam has been discovered in the north-
eastern portion. Trap dikes have not been noted, but the glacial
deposits and their attendant terraces are very widespread. 3
Series 1. The gneisses present exposures which do not yield in
point of interest to any other areas in the Adirondacks. They
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GEOLOGY OF HAMILTON, WARREN AND WASHINGTON COUNTIES 159
_ deserve much more detailed study than we have been able to
give them, and, when this has been done, the genetic and struc-
tural problems can no doubt be pushed well along toward solu-
tion. The gneisses embrace some varieties that are certainly
altered sediments. The latter are thinly schistose, richly mica-
ceous and often abundantly provided with quartz. They exhibit
in many exposures marked evidence of severe dynamic metamor-
phism, and have evidently been subjected to extremely powerful
compression. When broken parallel with the schistosity, they
show the small. surfaces along which individual lenses have
slipped and rubbed. Results like these are characteristic of de-
formation in the zone of fracture and under comparatively small
load—according to the phraseology and conceptions established
by Van Hise.
Other varieties of gneisses are more massive and seem to have
suffered less granulation. They present varieties consisting of
quartz, hornblende orthoclase and plagioclase and are less cer-
tainly derived from sediments. In a number of exposures appears
the coarse variety with the large lenses of quartz in the midst
of microperthite, which has been met in the northern Adiron-
dacks, particularly by Prof. Cushing near Franklin Fa‘ls, Frank-
lin co. This variety of rock is probably an altered conglomerate.
In the vicinity of the crystalline limestones, quartzites or
quartzose gneisses appear which are beyond question metamor-
phosed sandstones, and which will be referred to under series 2.
We have also met a few exposures of the dark green gneisses,
which are regarded as metamorphosed augite syenites, such as
were referred to in our last report as the “ Whitehall type.” The
exposures, so far as observations go, are not specially numerous,
but additional fieldwork may disclose more of them. |
The western line of the town is not easily reached without
camping, a mode of operation which we have been unable to
adopt, but there is little doubt from our observations in Hamilton
‘county, as shown by the maps elsewhere printed in this report,
_ that the gneisses cover practically all this portion. There may
_ be however, specially on the northeast, developments of anortho-
160 NEW YORK STATE MUSEUM :
site, aS we are uncertain how far the area there partially colored
may extend.
The prevailing strikes of the gneisses are northeast and north-
west. The dip is more often to the east than to the west, though
some western ones have been recorded. These relations are prob-
ably due in part at least to faulted blocks, whose steep escarp-
ments look off to the westward. The drainage lines are in most
cases either northeast and southwest or northwest and southeast,
following great structural breaks along these directions.
Hornblende schists or amphibolites are occasionally present in
the areas colored as gneiss, and in one or two cases either in the
township or just across its northern boundary they contain very
coarse crystals or crystalline masses of garnet. The garnet has —
proved of economic value as an abrasive and is mined, crushed,
sized and marketed. Moore’s mine, on Gore mountain, is one
locality, and the North River garnet co.’s mine just north of the
boundary of the township is another.
Series 2. The limestones and their associated beds are found in.
four separated areas, aS drawn on the map, but, though the sign
for gneiss appears between them, it is quite possible that under
the concealing drift, they may be present instead of the gneiss.
The typical limestones are coarsely crystalline varieties, almost
always containing disseminated serpentine. They seldom reach
more than a few feet in thickness, and are interbedded with
quartzites, thinly schistose gneisses, hornblende schists and
granular, pyroxenic aggregates. Scapolite rocks seem likewise
to be present.
In addition to the areas mapped there is.a small bed of lime-
stone in the ledges west of the town of North River, a continua-
tion or associate of the much larger exposures on the east bat of
the Hudson in Chester.
Graphite is quite commonly present in the limestones and is
somewhat richly disseminated in some of the quartzites asso-
ciated with them. In one or two instances it has attracted some
attention from prospectors. |
Series 3. The anorthosites have been discovered ae Mr New-
land in two localities.. One is on the west shore of Thirteenth
GEOLOGY OF HAMILTON, WARREN AND WASHINGTON COUNTIES 161
lake and extends for a considerable and as yet unknown distance
to the westward. The principal rock present is a coarsely crys-
talline aggregate of labradorite with very little of the dark sili-
cates present. ‘There is evidence of crushing, but there has been
- slight if any development of gneissoid foliation. Specimens were
collected near the outlet of Thirteenth lake which show sharp
eruptive contacts against the gneiss. Gabbros of basic character
likewise appear along the northern side of this area.
The second area lies to the south of the first and is near the
road leading from Bakers Mills to Wellstown. The anorthosite
is rather strongly gneissoid and has been more sheared than in
the northern locality. Mr Newland observed however a good
eruptive contact against the gneiss.
The exposures of the anorthosites are the most southerly of
those yet discovezed in the eastern mountains, and probably mark
the limits of the formation in this direction. In statements of
this character, mention should however also be made of the
augite syenite gneisses, which may belong with the anorthosites
in their geologic relations and which were referred to under
series 1.
Series 4. Along the brook that heads to the westward from
North River and about 2 miles from the village numbers of large
boulders of Potsdam sandstone are found, giving every reason to
think that they are not far from their parent ledges. There is
little doubt that there is an outlying area of the Potsdam at this
point, and the discovery adds another to the remnants of this
formation which have already been met, so far removed from the
larger southern exposures.
Series 5. No trap dikes have been observed.
Series 6. The glacial deposits are widespread and important
and should be a special object of study. Morainal material is
widely distributed. Glacial scratches have been observed in only
one instance, which was about 3 miles east of Bakers Mills. They
bore n 32 e magnetic, or about n 20 e true.
Along the Hudson there is one remarkable terrace about 40 feet
above the stream, and opposite the tributary streams are deltas
in very striking development, but our observations are not yet
sufficiently detailed to correlate them.
162 NEW YORK STATE MUSEUM
Washington county
Fort Ann
In the report of the state museum for 1897, p. 529-32, a prelimi-
nary sketch of Fort Ann township is published together with a
partial map. The topography and the drainage are there briefly
described, and some notes on the petrography of the gneisses,
crystalline limestones and gabbros of the eastern part of the erys-
talline area are given. In August 1898 Mr Hill spent several
days in traversing the ridges in the central and western part of
the township and as the results of his observations, the map has
been extended as shown in the accompanying plate. The high
ridge of Putnam mountain and the ridge connecting Pilot Knob
with Sugar Loaf on the western limits of the town are all gneiss
and apparently of the same general character as that already
described from Pinnacle mountain. Basic hornblendic bands
have been noted in a few instances. Also, near Mt Hope, sheared
augite syenites of the ‘‘ Whitehall type”, as described in our last
report, p. 507. Just west of Copeland pond gabbro has been dis-
covered in two places, viz, one on each of the highways.
The boundaries of the gneisses as against the paleozoics have
not been sharply delimited in the southwestern part of the town-
ship, partly because of the abundant drift and partly from insuf-
ficent observations. There is one outlier of the Cambro-Silurian
strata that lies on the gneisses to the northwest of West Fort
Ann. It is shown on the map prepared by Charles D. Walcott to
accompany his paper on the “Taconic system of Emmons, etc.”
(Amer. jour. of science. April 1888. pl. 3), and on the large,
geologic map of the state issued in 1894. While the crystallines
are drawn on the map where Mr Hill has observed them, the ob-
servations are not sufficiently detailed to revise the details of the :
earlier map, and the latter is on a scale so much smaller that in-
corporation is unfeasible.
One iron mine of considerable size was formerly operated near
Podunk pond.
ae
oe 9
2
2
San)
fad
Plate 4
INDE Xx
The superior figures tell the exact place on the page in ninths; e. g. 108’
means page 108, beginning in the third ninth of the page, i. e. about one
third of the way down.
Adams, F. D., cited, 90", 96°, 97°,
98°, 99°.
Adirondacks, crystalline rocks, 5*,
78-162; northern, topography,
75'-89'; drainage, 83'-89*.
Akerite, 108°. 7
Albite, 103’, 1077, 107’.
Allanite, 107°.
Altamont section, 56°-60°.
Amphibolite gneisses, 1107, 114°,
215°, 115° 116', 116°, 125°; contact
with granite, illus. facing p. 116.
Amphibolites, 110’, 116°, 160%.
Andesin feldspar, 98°, 98’, 111°.
Anorthite, 111°
Anorthosite-gabbros,
a 26°;
Anorthosites, of Franklin county,
a -105*, 78", 917 95°, 109°, 110°,
ieee, 1167, 116? 126" 126°,
127°; of Hamilton county, 142’,
143°, 145+, 1527; of Warren
county, 158, 159°, 160°-61';
Whiteface type, 103°-5’.
Apatite, 92°, 100°, 103°, 107°, 114’.
Arechaean rocks of § “Franklin
county, 89°-123+. ;
Augen gneisses, 103, 1437.
Auzgite, 987, 98°, 98", 100°, 1014, 101°,
1027, 103’, 106, 107", 1075 1117, 111°,
eet outte, : 118 PI IS ALS:
119%, 154°.
Augite syenite, 107’, 108°, 108°, 108°,
1097, 109%, 114°, 185°, 142%, 1597,
162°.
Ausable river, 84°, 86*, 88°,
102°-3', 114’,
Barlow, A. EH., on relations be-
tween Laurentian and Grenville
series, 911.
Becraft limestone, exposures, 54",
ba So GE 627, Gat ae
Becraft mountain, Oriskany fauna,
6°.
Benson, topography and geology,
141°-42°; geologic map, facing p.
141.
Biotite, 96°, 100°, 1027, 103°, 1077,
111°, 115*, 1437, 144°, 144° 154°,
Birch hill, illus. facing p. 78.
Bosses, 109%-10°*.
Bronzite, 106°, 1071, 107°, 1118, 118°.
Brookside farm, view looking north-
west, illus. facing p. 76.
Brunswick beds, 14*, 14°-15*, 15°-16*.
Building stone of Franklin county,
ge
Calcareous conglomerates, ° 18°-21'.
Calcareous shales, exposures, 58°.
Calciferous limestone, exposures,
near Alderbrook, 124’; near
Schroon Lake, 145’; in Wells,
148*; as road material, 127°.
Calciferous sandrock, exposures,
761.
Calcite, 92°, 1457, 1487.
Canadian geologists, latest conclu-
sions, 907-91°.
Canadian rocks, 89°-90*, 90".
Catamount mountain, illus.
p. 92.
Chalcopyrite, 100°,
facing
164 NEW YORK STATE MUSEUM
Chateaugay river, 88'-89*.
Olarke, J. M., investigations of
Portage fauna, 6°, 6°; investiga- -
tions of Oriskany fauna of Be-
craft mountain, 6°.
Clinton limestone, illus. facing p.
70. ‘
Clinton shales, exposures, 66°, 67°,
67°; thickness, 67°.
Coccolite, 155°.
Conglomerates, 13°,
posures, 18°, 20*.
Corals, fossil, generic characters,
68.
Cosgriff trap rock quarry, 29°.
Crystalline limestones, see Lime-
stones.
Crystalline rocks of Adirondacks,
d*, 78-1385; of Franklin county,
89°-123*.
Cushing, H. P., Preliminary report
on the geology of Franklin
county, 5*, 73-128; cited, 95°, 105°,
1097, 1237, 123°, 135°.
18°-218; ex-
Darton, N. H., cited, 24°, 34°, 41°,
53*, 63°, 65°, 67°, 687, 146°.
Deer river, 88'-89*.
Deltas of Warren county, 161°.
Diabase, 227, 1177--19%, 127%. See
also Trap rock.
Dictyospongidae, memoir on, 6°.
Dikes, in anorthosite, 102%, 117°;
diabase, 1187-19°; of Franklin
county, tabulation, 120-22; gab-
bro-diorite, 918; gabbros, 109’,
110°, 114*; in Newark rocks, 42°-
43?; of Siluric age, 1237; syenite,
117°; syenite porphyry, 118°'; trap,
143°, 144’.
Diorite, 91°, 98°.
Dolomite, 123°, 148%.
Drainage of Adirondacks, 83'-89*.
Economic geology of Franklin
county, 1257-28%,
Emmons,
146°.
Esopus shale, exposures, 55°, 61°,
65°, 72°; thickness, 65°.
Ebenezer, cited, 125°,
Faults in Newark rocks, 44°-49°.
Feldspar, 96°, 977, 974, 97°, 100%, 103°,
107, 107, 107, 107) eee
112", 113°, 114, 1145 is ee
ALT, 319), 142? 145% oe See
also Andesin feldspar; Labrador-
ite; Orthoclase feldspars; Plagio-
clase feldspars.
Feldspathic sandstone, 154".
Fort Ann, topography and geology,
162'; geologic map, facing p. 162.
Fossils, in Helderbergs, 53-72; in
Trenton limestone, -149'-50*; in
Utica slate, 151'.
Franklin county geology, report of
H. P. Cushing, 5°, 73-128; geologic
map, in back cover.
Furnace mountain, illus. facing p.
80.
Gabbro-diorites, 98°.
Gabbroic gneisses, 94°, 94*, 104°.
Gabbros, anorthosite, 102°-3*, 114, .
1268; hypothetic gabbro core of
Adirondacks, 183’; represented
on Geologic map, 132°; of Frank-
lin county, 109°-14°, 99°, 99°, 101%,
101°, 1027, 102°, 106", 107 ta
1157, 116%, 126°, 127°; of Hamilton
county, 143°, 145°, 1527; of War-
ren county, 158°, 1617; of Wash-
ington county, 162°.
Gallupville, sections: near, 62'-63".
Garnet, 941, 100°, 1027, 103%, 107°,
110°, . 111°,. 112%, 113°, 114, ae
118', 144°, 144°; mines, 160°.
Geologie map, completion, 5°; color-
ation, 6"; progress in mapping
crystalline rocks of Adirondacks,
129-35.
INDEX
Gill, A. C., acknowledgments to,
754.
Glacial boulder on Palisades, illus.
facing p. 16.
Glacial deposits, of Hamilton
county, 142%, 142°, 148°, 152’, 157°;
of Warren county, 158°, 161°.
Glacial sands of Hamilton county,
156°,
Gneisses of Adirondacks, age, 90°-
927, 94%, 134°, 184°; all parts not
of same age, 134*; of Alexandria
Bay, 184; amphibolite, 110°,
114°, 115°, 115°, 116', 116°, 125°; con-
tact with granite, illus. facing p.
116; anorthosites changed to, 101°;
augen, 1031, 1487; augite syenite,
a08") 114"). 135%, 142°, 159%, 1615;
boulders, 143°, 1527; chief rock of
Adirondacks, 133°; doubtful, 94%,
95*-99*; of Franklin county, 78°,
89°-927, 93*, 947, 95*-99*, 1015, 1037,
104°, 108*, 1107, 114® 115°-167, 116°,
125%, 127’, 135°; gabbroie, 947, 94"*,
104°; granitic, 94*, 967-97°, illus.
facing p.. 78; graphitic, - 110°;
of Hamilton county, 142',
fee elas 44 P50, 152",
154°-55", 155°, 157°; hornblendic,
941, 987-994, 1347, 1347, 144° 152°,
154*, 157%; igneous, 89° 94*, 95%-
96", 132*, 184°; intrusive rocks,
93*, 1167; gneisses and lime-
stones, time relations, 134°-35*;
represented on Geologic map,
132+. 135‘; origin, 89*, 90°-92?, 944,
95°-967, 1324, 184°, 184°, 159"; ortho-
clase, 78°, 907, 99*, 116', 116°, 1257;
orthoclase-quartz, 96'-97°; peb-
bles, 1507; plagioclase-hornblende-
augite, 115°; pyroxene, 98'-
99*; pyrrhotite, 155°; quartzose,
93°, 1277, 159°; red granitoid, 134°;
schistose, 160°; metamorphosed
sedimentary masses, 89° 154°,
159'; syenitic, 94‘, 135°, 144°, illus.
165
facing p. 108; of Warren county,
1587, 158°-60*, 160", 1615; of Wash-
ington county, 162‘.
Gneisses of Canada, 89°, 907.
Granite, in Franklin county, 95’,
Oe 106 108) TIT. 26": aE
Hamilton county, 144*, 154, 154°;
contact with amphibolite gneiss,
illus. facing p. 116; hornblendice,
154*, 154°; represented on Geologic
map, 132°; pyroxene, 154°.
Granitic gneisses, 94*, 967-97°; illus.
facing p. 78.
Granitoid gneiss, 134°.
Granophyr, 100°.
Granulites, 98'-99*.
Graphites, 92°, 93°, 93°, 1457, 1555,
1H: 155", 16O®:
Graphitic gneisses, 110°.
Great Chazy river, 887-89*.
Grenville series, 89°-90", 911, 927-95*;
illus. facing p. 94.
Gypsum quarry, 677%.
Hall, C. E., cited, 124’.
Hall, James, death, 7°; memorial,
7°; cited, 68°, 146°.
Hamilton county, geology, 5%, 187-
G2: erystalline rocks, 131°, 133%.
Hamilton group, exposures, 56%, 657,
feat
Haplite, 154’.
Helderberg limestones, thickness,
658.
Helderberg plateau, sections of for-
mations along northern end, 7’,
51-72.
Helderbergs, illus. facing p. 58, 54,
60.
Herkimer county, crystalline rocks,
ise 133%.
High Tor, illus. facing p. 10, 26.
Hill, B. F., Preliminary report on
the geology of Hamilton, Warren
and Washington counties, 137-62.
166
Hope, topography and_ geology,
142*-43°; geologic map, facing p.
141.
Hornblende, 112°-14?, 96°, 978, 100°,
102% 203% L075, 200, (1058 i.
115°, 1428, 1431, 144°, 154°, 159°.
Hornblende gabbros, 114’, 114°.
Hornblende gneisses, 94', 987-99%,
134’, 134", 144° 152°, 154*, 157°.
Hornblende schist, 160°, 160’.
Hornblende syenites, 108%, 108°.
Hornfels, 35*, 36°, 36’, 37’.
Howe’s cave, illus. facing p. 68, 70.
Howe’s cave sections, 677-72’.
Hudson river formation, exposures,
be Ot OF, OL.
Hyperite, 114*, 114°, 114°, 116%, 117°.
Hyperite gabbros, 115’.
Hypersthene, 98’, 98°, 987, 100°, 101°,
IDZ IOS AOE, 10 Te: aa.
nO Poon I Be is
Ilmenite, 100°, 111°.
Indian Ladder, illus. facing p. 54.
Indian Ladder section, 537-56°.
Indian Lake, topography and geol-
ogy, 156-577; geologic map, fac-
ing p. 141.
Iron mine in Washington county,
162".
Iron ore of Franklin county, 103°,
125*-26%.
Iron pyrites, 66°, 67’.
Jefferson county, crystalline rocks,
158°,
Johnsburg, topography, 157°-58';
geology, 1587-61°; geologic map,
facing p. 158.
Kemp, J. F., Preliminary report
on the geology of Hamilton, War-
ren and Washington counties, 5%,
187-62; work with H. P. Cushing,
75°: cited, 103%, 109°, 1237, 124’,
141%, 145°,
NEW YORK STATE MUSEUM
Knox, section near, 60*-61°.
Kitimmel, H. B., Newark or new
red sandstone rocks of Rockland
county, N. Y., 5%, 9-50.
Labradorite, 99°, 1014, 1015, 101’,
103", 104', 104°, 1117, 1119 ae
1127) 115% 41602,
Ladentown, caleareous conglomer-
ate, 21°.
Ladentown trap, 39°-42?.
Lake Placid, 88°.
Lake Pleasant, topography and ge-
ology, 153'-56*; geologic map, fac-
ing p. 141.
Lakes of Adirondacks, 837-84.
Laurentian series, 89°, 91.
Lime in Franklin county, 128".
Limekiln, calcareous conglomerate,
Pl he .
Limestones, in Ramapo mountain,
LOR: :
of Adirondacks: represented on
Geologic map, 132"; and gneisses,
time relations, 134°-35°; in Frank-
lin county, 92°-93°, 104°, 110°, 123°,
124*, 124°, 1247, 128; in Hamilton
county, 145', 1557-567, 1575; in
Warren county, 158’, 160°. See
also Grenville series.
Limonite, 150°.
Lockatong beds, 13’, 14*, 14’.
Logan, Sir William, cited, 89°.
Long Clove, trap rock, 30°-31'; illus.
facing p. 10.
Luther, D. D., investigations con
waterlime beds, 6°; investiga-
tion of fossil faunas of Portage
rocks, 6+.
Lyon mountain, mines, 125°.
Magnetite, 96°, 107°, 1117, 111°, 112°,
113* dd4* 7154) 36", 150".
Manhattan trap rock company’s
quarry, 27°, 36°.
Marble, 928-937, 145°,
INDEX
Marcellus shale, exposures, 567, 72°.
Medina sandstone, outcrops an
contacts, 6°.
Merrill, F. J. H., cited, 100°.
Merrill, G. P., cited, 93.
Microcline, 115°.
Microperthite, 1077, 115°, 142°, 142°,
144°, 150°, 154°, 159°.
Minerals, in anorthosite, 99°-105°; in
diabase, 117*-22°; of economic val-
ue, in Franklin county, 125?-26';
in gabbros, 109°-14°; in gneiss, 967-
-99*; in granite, 114°-17*; of Gren-
ville series, 92°-95*; in sSyenitic
rocks, 105*-9°; table, 120-22.
Muscovite, 154’,
Newark rocks of Rockland county,
. 5‘, 9-50; reptile and other verte-
brate tracks, 14°; thickness, 21°;
conditions of formation, 49*-50°.
Newland, D. H., Report on progress
made, during 1898, in mapping
the crystalline rocks of the west-
ern Adirondack region, 129-35;
Preliminary report on the geolo-
gy of Hamilton, Warren and
Washington counties, 137-62;
cited, 141+.
Niagara limestone, exposures, 66’,
68°; illus. facing p. 70.
Norites, 101°, 1027, 111°.
Nyack, sandstone exposures,
trap rock exposures, 26°, 33°.
Do ee
Oligoclase, 98°, 1077, 107°, 1077, 115°.
Olivine, 119%.
Onondaga limestone, exposures, 56°,
fae. G3 65". 72".
Ontario county,
map, 6°.
Ophicalcites, 93%.
Oriskany fauna of Becraft moun-
tain, 6°.
Oriskany sandstone, exposures, 55°,
59%, 60%, Git, G3*.65*,: 727.
revised geologic
167
Orthoclase feldspars, 93°, 96°, 987,
= 98°;'99*, 100°, 107’, 107°, 114°, 142°,
142°, 144°, 144°, 154° 154°, 159°. .
Orthoclase gneisses, 78°, 90°, 967-97°,
99*, 116’, 116%, 125°.
Oswego sandstone,
contacts, 6°
outcrops and
Paleontologic investigations, 6’, 6".
Paleozoic rocks of Adirondacks,
thickness, 76°; of Franklin coun-
ty, 1238%*-25'; of Warren county,
161°; near Wells, 145°-52°.
Palisades, 22°-39°; causes of eleva-
tion, 38*; illus. facing p. 10, 22,
26. :
Pegmatite, 97', 144°, 145°, 154’, 155°.
Pentamerus limestone, exposures,
53%, 547, 577, 58%, 59°, 60°, 62%, 63%,
64°, 66°, 70°, 71°; illus. facing p. 54,
60, 68; quarries, 67°, 71°; analysis,
7 (3 teas
Phlogopite, 92°, 155°.
Piermont, sandstone exposures, 16°;
trap rock exposures, 25°-26%, 36%.
Plagioclase feldspars, 96°, 98°, 98°,
LOT 1112, 115") 144, 444; 250%;
154°, 154°, 159°.
Porphyrites, diabase, 119°.
Porphyritic gneisses, 103*, 1437.
Porphyry, syenite, 117°, 118°, 118°.
Portage fauna, investigations, 6°, 6’.
Portage formations, report on strat-
igraphy and paleontology, 7’.
Portland cement, manufacture, 71°.
Potsdam sandstone, exposures, 75°-
76°, 145°, 147°-48'; building stone,
126°; road material, 127°; boul-
ders, 161°.
Precambrian rocks
county, 89°-123*.
Prosser, C. 8., Sections of the for-
mations along the northern end
of the Helderberg plateau, 7°, 51-
72.
Pyrite, 937, 100°, 107°, 114°, 144°, 150°.
of Franklin
168 NEW YORK
Pyroxene, 92°, 93', 93%, 93’, 97°, 987,
~ 985, 987, 113°, 115°, 1457; 154°, 155%,
155°.
Pyroxene gneiss, 98'-99+*.
Pyrrhotite, 100°, 114’, 155°.
Pyrrhotite gneiss, 155°.
Quartz, 93*, 937, 96°, 971, 97+, 98°,
100°,° 103%, -1067;- 06% 107° 2085,
108%, 108°, 114%, 115*, 116°, 142°,
144°, 144°) 1457 145°” 147°, 148%,
149”, 150°, 154°, 154°, 155°, 1597, 159°.
Quartzites, 150’, 155*, 155°, 159°, 160°.
Quartzose augite syenite, 109’.
Quartzose gneiss, 93°, 1277, 159°.
Quicklime, 71’.
Racquette river, 84°, 86*, 87°-88’.
Ramapo mountain, 19°.
Red sandstone rocks of Rockland
county, 5’, 9-50; thickness, 21°;
conditions of formation, 49°-50°.
Rivers in Adirondacks, 84°-89*.
Road metal of Franklin county,
12.
Rockland county, Newark rocks, 5‘,
9-50; geologic map in front cover.
Rockland Lake, trap rock, 28'-29°.
Ruedemann, Rudolf, cited, 146°.
St Lawrence county,
rocks, 181°, 133%.
St Regis river, 84°, 86*, 88°; illus.
facing p. 118.
Salmon river, 88’-89*.
Sandstones, 13°; exposures, 16*-18°,
20, 537, 60°; effect of contact with
trap, 35'-36'; feldspathic, 154’.
See also Potsdam sandstone.
Saranac river, 84’, 85*, 86*-87°.
Sarle, C. J., investigations, 6°.
Scapolite, 93+, 937, 160%.
Schaeffer, C. O., cited, 69°, 71°.
Schist, 134°, 144‘; hornblende, 160’,
1607.
Schistose gneiss, 160’.
crystalline
STATE MUSEUM
. schobarie grit, exposures, 55°.
. Schoharie sections, 688-67’.
Serpentine, 93', 160°.
Shales, 13°; exposures, 16*, 187, 344,
537, 607, 60°, 651, 677 115, Ta ee
fect of contact with trap, 35'-36*.
Short Clove, trap rock, 31?-32'; illus.
facing p. 10.
Silicates, 142°, 150°, 154’, 161°. See
also Augite; Hornblende; Pyrox-
ene. ;
Sillimanite, 93°.
Siluric age, eruptive rocks, 123'.
Simpson, G. B., work on generic ~
characters of fossil corals, 6°.
Smyth, C. H., jr, Report on progress
made during 1898, in mapping the
crystalline rocks of the western
Adirondack region, 5%, 129-35;
cited, 90°, 105%, 109°.
Sparkill, trap rock, 327.
Stockton beds, 138’, 14*, 15+,
Streams in Adirondacks, 84°-89+*,
Suffern, sandstone and conglomer- |
ate beds, 20*; trap, 427.
Syenites, relation .to anorthosite,
109°; represented on Geologic
map, 182°, 135°; of Franklin coun-
ty, 99°, 101°, 102%, 105°-9°, 110°, 114°,
116’, 116°, 126°, 127°; of Hiamalton
county, 142°; of Warren county,
159’; of Washington county, 162°. -
Syenitic gneisses, 94*, 185°, 144°;
illus. facing p. 108. ,
Syenitic porphyries, 117°, 118°, 118°.
Tentaculite limestone, exposures,
53*, 543, 574, 634, 64+, 66%, 69°, 70°;
illus. facing p. 54, 68; quarries,
66", 67°, 712; analysis, 71°.
Titanite, 92°, 100°, 103°, 107°, 114°,
125°..195%
Trap dikes, 143°, 144’.
Trap rocks, 22'-42°; contact with
sandstone, 32°; upper contact of
trap and shale, 32'-34°; effect on
INDEX
neighboring shales and _ sand-
stones, 35'-36'; exposures, 25°-34’;
hight, 23°-24*; local examples of
metamorphism, 36'-37°; other ef-
fects than metamorphism, 37°-38';
relation to the sandstones, 24*-25°;
local details of structural rela-
tions, 25°-32'; thickness, 38°-39°;
~ width,. 228-237, See also Diabase.
Trenton limestone, exposures in
Wells, 148%-50’.
Trough Hollow, trap rock, 30’.
Union hill trap, 42’.
Utica slate, exposures
1508-52°,
in Wells,
Valley Cottage, trap rock, 33°.
Van Horn, F. R.,-cited, 1137.
Vanuxem, Lardner, cited, 146°.
169
Verdrietege Hook, sandstone expo-
sures, 17*; trap rock, 26°-27'; illus.
facing p. 22.
Walcott, C. D., cited, 53°, 162".
Warren county, geology, 5°, 137-62.
Washington county, geology, 5°,
137-62.
Waterlime beds, investigations on,
6’; exposures, 54’, 57%, 64*, 67°, 68".
Wells, geology, 143°-52°; topogra-
phy, 148*; geologic map, facing p.
141, 144.
West Mountain, 63°.
Whiteface type of anorthosite, 103°-
5,
Whitehall type of gneisses,
162°,
159’,
Zircon, 103°, 107°, 150°, 155°.
28 foe Sane
- « Sy ee a eT —— a f + 9 - = ‘ PO eet 7
, Pal gy Mage» a i. ee - ' ; = Peek . y : .‘ >
aS ep ie oN ig te ee a .% “ Y . > : na te -
: ae ster =e - oe - : = ’ Nn ee Se) Ce ee eS ee
a oe ee Se ee, ee = BA Je eS . eo ;
Oe ee eee eee eee Se
UNIVERSITY OF THE STATE OF NEW YORK
STATE MUSEUM
18 rep. State Geologist and Paleontologist
7430" 7200"
LEGEND
LOWER SILURIAN
CAMBRIAN
Potsdam sandstone
‘ai PRE-CAMBRIAN
22
Y
Diabase dikes
Syenite and granite
Anorthosite and gabbro
Grenville series
Gneisses of unde-
terminedage and origin
\ NEF cnt aia co =
7) Childvwold 3
r | ildwwold) S\
\
eS
GEOLOGICAL MAP OF FRANKLIN COUNT
BY H SHING ‘
‘Wi NU
3 9088 01300 5772