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186 Cincinnati Society of Natural History. 
touched, in others the prominences were just touched by the grinding 
operation, partially worn down, or entirely obliterated, leaving a flat, 
but unpolished surface, and in many other places the surface is 
polished, and grooved. The grooves are, in width, from lines scarcely 
visible, to those three fourths of an inch wide, and from one fortieth to. 
one eighth of an inch deep, and traverse the quarry from between N. 
19° to N. 33° west, to the opposite points, in lines exactly straight, and 
in fassicles of sometimes 10 in number, exactly parallel, cleanly en- 
graved in compact limestone, without seam or fault of any kind, and in 
a surface ground down to a perfect plane. The grooves appear as if 
they had been formed by icebergs floating over the terrace, which ‘is 
the highest in the neighborhood, and dragging gravel and bowlders 
frozen into its lower surface, over the plane of the stone. 
In 1842, Lardner Vanuxem* found the drift scratches in Central 
New York confined to no particular rock, and at no particular elevation, 
but not uncommon, and corresponding, in direction, with the course 
of the valley, or of the valleys in which they occur. One of the 
best localities for observing the phenomena is at a quarry two and a 
half miles northeast of Amsterdam. The surface of the rock is covy- 
ered with soil and earth, which, when removed, shows a water-worn sur- 
face with two or three sets of scratches, exhibiting great regularity, and — 
having a common direction toward the east, one set of which is about 
eight degrees south. The scratches, including furrows, are generally 
from a mere line to one fourth of an inch wide, and from one to two 
tenths of an inch and more in depth. Some of them show that the 
moving power which produced them, passed over the sarias with a 
vibratory or tremulous motion. 
In 18438, Prof. James Hall} said that the northern part of the fourth 
district of New York, and the low slopes and deeper valleys of the 
southern part, are covered to a greater or less depth by superficial 
materials of more northern origin, mingled with those of the rock on 
which the deposit rests. All the formations have suffered greatly 
from denudation, and the abraded fragments of each constitute a 
large proportion of the superficial detritus resting on its southern 
neighbor. The size of the fragments always bears a proportion to the 
distance they have been transported from the parent rock. Often, a 
huge mass of a northern rock rests upon the margin of the one next 
south of it, while at a distance of 10 or 20 miles farther south, only small 
* Geo. 3d Dist., N. Y. 
+ Geo. Sur. 4th Dist., N. Y. 
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