METAMORPHIC ROCKS. 
447 
flagging stones, of the granular quartz rock, may be opened at this place. The strata are 
nearly vertical, and the stones may be split off with great ease, if the quarry be opened in a 
proper manner. The flagging and curbstone used in New-York, and many other towns, are 
now brought from the Bolton and Haddam quarries in Connecticut, and from the greywacke 
quarries in Greene county. The Bolton and Greene county stone are carted from eight to 
sixteen miles over bad roads, and then shipped to a market. If stone, as beautiful and as 
durable, can be dug on the shore of the Hudson, where no cartage is required, and where 
the expense of quarrying is no greater than at the quarries mentioned, and where the busi¬ 
ness is now very lucrative, it follows that such quarries on the shore of the Hudson would 
be very valuable. 
The talcose slate, distinctly characterized, is limited in extent. It occurs in Westchester 
and Putnam counties, forming a range of hills several miles in length. It forms Blue-rock 
point, on the post road, between the crossing of Peekskill creek and Annville. The slaty 
lamince are parallel in direction to the limestone and granular quartz rock on the east, which 
dip at an angle of from seventy-five to eighty-five degrees to the east-southeast. This rock forms 
the principal mass of the hills to the north-northeast of Blue-rock point for several miles. 
Gallows hill, (a place celebrated during the Revolution, in consequence of the public execu¬ 
tions,) is a part of this range of rock. The rock is generally covered by soil, except where 
it has been denuded by water, or excavations for roads, etc. The soil is of good quality, and 
produces fine crops. Farther northeast, this rock is rarely seen ; but it passes up Peekskill 
hollow, and up a valley two or three miles west of Boyd’s corners in Putnam county. It is 
very refractory in the fire, and is used for the in-walls of furnaces. The rock is very fissile, 
and splits in thin laminae of some magnitude. 
Diluvial scratches were observed on the outcropping edges, in many places, where the sur¬ 
face was exposed by uncovering the rock in making and repairing the roads. They are very 
distinct on the road that passes from Gen. Van Cortlandt’s mansion over Gallows hill, on the 
western declivity. Like hundreds of similar localities observed in Columbia and Dutchess 
counties, the general direction is from N. 20° to 30° W., to S. 20° to 30° E. Veins of 
quartz were occasionally seen traversing the talcose slate. In some places the quartz was 
loaded with pyrites ; and where the slate had decayed, and the masses of this mineral were 
scattered about on the ground, they had the spongy texture similar to the quartz from the 
veins and nests in the slates of Columbia and Dutchess counties. The cavities are also fre¬ 
quently filled with oxide of iron, like the quartz in the gold region of Virginia and North- 
Carolina. No gold was, however, seen ; and it is hoped that a sufficient number of fruitless 
researches for gold, silver and coal, have been made in this vicinity, to deter others from future 
enterprises of such a nature, where the expense is certain, and the returns so very, very 
uncertain. 
The talcose slate, at its junction with the grey and whitish limestones, is highly loaded with 
carbon and with pyrites. The one has given origin to the reports and stories of valuable coal 
beds in this region, and the other to the existence of gold and silver mines. 
