UPLIFTS OF THE MOHAWK. 
209 
The seventh uplift or series, is that of Little-Falls. It presents the same barrier-like 
appearance, at the east end, as the Noses, with no equivocal character as to origin at all 
observable ; the valley at both extremities on both sides of the river presenting the slate in its 
integrity, with, however, a thick shield of alluvion on the north side, at the west or upper end. 
It is the only one which the river has not succeeded in cutting down to a level at both ends ; 
probably owing to the great height as well as the breadth of the gneiss which forms its base, ex¬ 
tending as it does from the east to the west end, and forming the bed of the river, over which 
the water falls. The uplift presents a wall on the east side, rising above the range of slate to 
some height on the north side of the river, and only broken where the river finds its passage. 
The gneiss rises at the east end to the height of a hundred feet, and disappears under the 
calciferous rock and the river at the west end. On the north side of the gap, its overlying 
rock, towards the east end, has been removed, presenting a terrace of many rods in breadth, 
and showing a greater breadth of river when at that height. On the south side the terrace is 
but a narrow one. 
An interesting feature in the gap, as regards its antiquity and the progress of excavation, 
are the pot-holes in the primary rock. They are found at different elevations, some high above 
the present level of the river. They are numerous in the bed of the river, and occur between 
the river and the level of the aqueduct; at the railroad house ; and in the wall of rock which 
rises above the road going east, after crossing the bridge. At this latter place, a section of 
one of them may be seen, extending from the top of the cliff to about fifteen feet below, look¬ 
ing like a niche for a statue, but reversed. These holes are obviously due to the rubbing or 
grinding of stones, put in motion by an oblique movement of waters, where rapids or falls 
exist. 
The calciferous sandrock forms the whole mass which rises upon the primary on both sides 
of the Gap, extending north and south as in wood-cut No. 70. In part it rises vertically, 
showing a thickness of over two hundred feet: it is thicker at the west than at the east end. 
Its layers appear in the gap to be nearly horizontal, owing to the course of its excavation 
having been in the line of its bearing, the dip being about southwest. The fucoidal layers 
were not noticed, except at the old mill in the direction of its slope ; they were but thin. 
70. 
No. 3. Birdseye limestone. 
4. Trenton limestone. 
No. 1. Primary rock, gneiss. 
2. Calciferous sandrock. 
Geol. 3rd Dist. 
No. 5. Utica slate. 
27 
