380 
GEOLOGY OF THE FIRST DIsfRICT. 
Section three-quarters of a mile northwest of Burton’s bridge 
No. 
Kind of rocks. 
Thickness. 
No. 
Kind of rocks. 
Thick 
1 
Calciferous orit two la ers 
Feet. 
5 
Inches. 
0 
8 
Grit. . 
Feet. 
1 
Inches. 
6 
2 
4 
0 
9 
Shales... 
3 
0 
3 
Calciferous grit. 
6 
6 
10 
Grit— six layers. 
6 
0 
4 
Calciferous grit—four layers. 
6 
0 
11 
Calciferous grit. 
4 
0 
5 
Shale. 
0 
4 
12 
3 
6 
6 
Grit. 
3 
0 
13 
Calciferous grit — three layers .... 
3 
0 
7 
Shale. 
1 
0 
14 
Calcifprniis arif.. 
4 
0 
50 
10* 
Section at Alexander's bridge, at the Upper aqueduct atross the Mohawk. 
No. 
Kind of rocks. 
Thickness. 
No. 
Kind of rocks. 
Thickness. 
Feet. 
Inches. 
Feet. 
Inches. 
1 
Plates 1 III 
7 
Slate . 
0 
4 
2 
Slates with thin bands of grit. 
30 
0 
8 
Compact grit. 
1 
6 
3 
Compact grit. 
4 
0 
9 
Slates and shales. 
3 
0 
4 
5 
0 
10 
2 
8 
. . 
1 
0 
11 
3 
6 
6 
Compact grit..... 
5 
0 
12 
Slates at the level of the Mohawk . 
56 
0 
At a locality near the last section, Mr. Seymour remarks, “ Here also an interesting move¬ 
ment has taken place. It seems that the rocks, having been bent in the form of an arch, were 
broken, or a rent made, through which the river flows, and then an upheave effected,” as 
illustrated on Plate 40, figs. 4 and 5.t 
The surface rocks of nearly all of Schenectady county are the grits and shales, of which 
sections have been given. In a few places, the black fossiliferous slates of the Utica slate, 
and the Trenton limestone, are exposed. 
The line of the railroad between Schenectady, Ballston and Saratoga, presents some sec¬ 
tions of the rocks of the Hudson-river group ; but they do not differ from those of the pre¬ 
ceding sections, except that the black graptolitic or Utica slate is exposed in some places. 
Hudson-river group east of the Hudson. 
We have thus far described some of the characters and phenomena of the Hudson-river 
rocks on the right bank of the Hudson, and have kept them distinct from those of the left 
* The calciferous grit, and the grit in these sections, are the same rocks that have been formerly called greywacke. The cal- 
ciferous grit effervesces very slightly with acids. The shales and slates are the same as the greywacke shales and slates, 
t Manuscript Notes of the Survey. 
