588 
GEOLOGY OF THE FIRST DISTRICT. 
Again near J. H. Howland’s seat, grooves east side of the road. Direction of grooves N 
45*^ W. Strike N 30° E. Dip vertical. 
A few rods south of six-mile stone, on west side of road, the grooves in pure gneiss, direc¬ 
tion, as before, N 45° W. Strike N 40° E. Dip vertical. ' 
Near Mr. Francis’ country seat (still north of the six-mile stone) and corresponding with 
96th-street, on the east side of the road, the grooves perceptible only. Strike N 30° to 35° 
E. Dip vertical. 
97th to 98th-street, and opposite to the house of Mr. John Darks, the gneiss is well strati¬ 
fied, appears on the east side of the road, and is covered with grooves. Direction of the 
grooves N 45° W. The rock uncovered extends north and south one hundred and twenty 
feet, and east and west twenty feet. Dip W 80°. Strike N 35° E. 
Near 103d-street found boulders of the anthophyllite, dark variety, with others of green¬ 
stone, granite, &c. 
Again near 109th-street, grooves on east side of the road. Direction N 45° W. Dip 
vertical. 
On the heights, a little before we reach the Lunatic Asylum, and the west side of the road, 
the grooves run N 45° W. They are an inch and a half deep, and six to eight inches wide. 
Strike N 35° E. The same grooves seem to be continued to the east side of the road, for 
the rock continues two hundred feet northeast and southwest, and is covered with grooves as 
above, running N 45° W. This rock occupies the enclosures of Mr. Stevens, whose house 
is on the east side of the wa}'^, and may be recognized by having an immense boulder of 
granite resting on the rock near the southwest corner of the house, and is nearly round, having 
a diameter of between ten and eleven feet. There is one very large groove between this 
boulder and the northwest, whence it came. It seems to have been cut by this very rock, 
inasmuch as it terminates with the boulder on the southeast, and is covered by the soil in less 
than a rod from the boulder. This groove is three inches deep and eighteen inches wide. 
There are a great abundance of others side by side with this, but none so large. The gneiss 
is very compact, and suitable for building. 
Directly by the lane leading to the enclosures of the Lunatic Asylum, the gneiss again 
appears above the surface. Strike N 30° E. Dip 85° to 90° E. Grooves also abundant, 
and running N 45° W. 
Again opposite 116th-street, grooves running N 45° W. Strike N 30° to 25° E ; twenty 
to thirty feet north and south, uncovered. 
We now leave the road and proceed on the heights south of Harlem and Manhattanville 
valley, to 8th avenue. 
Leaving the road at the southern limits of the village of Manhattanville, kept on the height 
of land which skirts the southern border of a valley which entirely crosses the island, and 
forms the basis of the village of Harlem at its eastern extremity, and that of Manhattanville 
at its western. The southern border of this valley, which I shall distinguish by the name of 
Harlem and Manhattanville valley, especially on the western half of it, lies in a direction 
