452 
GEOLOGY OF THE FIRST DISTRICT. 
Stone. As the gneiss runs out at the mouth of the Spuytenduyvel creek, the whole ridge 
northward is limestone, the form and extent of which may be learned by inspecting the map 
of the island, where it is encircled by a line. The strike was examined in a number of places 
on the ridge of limestone, and varied from N. 25° E. to N. 45° E., and the dip from 50° E. 
to vertical. From Mr. Dykeman’s house, which is near the southern line of the limestone, 
to the old tide-mill (which is nearly opposite to Tubby hook), at distance half a mile or a 
little more, is a line of abandoned quarries, which many years ago were extensively wrought 
for burning into lime ; but as the lime was of inferior quality, other varieties at length super¬ 
seded it. This limestone has been called dolomite, but whether from its granular structure, 
or from its composition, I am unable to determine.”* 
Limestone of Westchester county. 
The limestone has the same dip and line of bearing as the contiguous gneiss and gneissoid 
rocks, and like them, is distinctly stratified. They all dip to the east-southeast (as a general 
rule, but there are local exceptions) at a high angle, varying from forty-five to ninety degrees. 
The limestone forms several nearly parallel ranges at intervals of two, three or four miles 
apart, ranging in a north-northeast and south-southwest direction. 
1. The most eastwardly deposit of this kind, and of any great magnitude, is seen on Gou- 
nerneur Morris’s farm, opposite Harlem, where it is quarried for making the piers for the 
railroad bridge, and for other purposes. It is generally grey, and in some places is much 
intermixed with mica. Many of the blocks, and even the rocks in place in the quarries, have 
so much the aspect of gneiss, that close inspection is necessary to distinguish them. The. 
limestone rock again appears in the bed of a small brook between Harlem and Westfarms 
village. It is thought probable that the Westfarms and Eastchester marble quarries are in 
this range, of limestone, which passes up the valley of the Bronx river by Whiteplains and 
Rye pond, and so on further to the north-northeast. 
2. Another range passes from near Macomb’s bridge in a north-northeast direction, is 
crossed by the aqueduct, and passes about two or two and a half miles west of Whiteplains. 
3. Another crosses from New-York island at Kingsbridge, and thence ranges north-north¬ 
east, and forms the shore for some distance. 
4. Another ranges from Dobbs’s ferry, in the same general direction, by the county poor- 
house and Ackerman’s iron mine. 
5. Another ranges north-northeast from Sparta, by Singsing, about a mile east of Pine 
bridge across the Croton river. Some parts of this bed are pure white marble ; some are 
dolomitic, and some have the aspect of gneiss, until closely examined. 
6. Another ranges from Verplanck’s point north-northeast to near Peekskill, where it 
changes its direction to the east. A mass of limestone, with a transverse line of bearing, 
viz. east and west, occurs near Henry J. Cruger’s mansion, two and a half miles southeast 
* Prof. Gale’s Report; Third Annual Geological Report of New-York, 1839, p. 183, 184. 
