290 Tertiary. 



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 scarcel}' 

 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 an}- 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 quarr}^ two and a 

 half miles northeast of Amsterdam. The surface of the rock is cov- 

 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 generality 

 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 surface with a 

 vibrator}- or tremulous motion. 



In 1843, Prof. James Hallf said that the northern part of the fourth 

 district of New York, and the low slopes and deeper valle3'S 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 

 ^hich the deposit rests. All the formations have suffered greatl}^ 

 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. 



i Geo. Sur. 4tliDist.,N. Y. 



