26 A GEOLOGICAL HISTORY. 



rock, of some elevation. There was once a very 

 large boulder of " Hudson River Slate" on Mr. 

 Myers' farm, near his house, this was one of the 

 largest pieces of this rock, which has been seen 

 south of the Highlands, it was long since broken 

 up, and used for building stone. 



At an old tavern, called the " Cross Keys," on 

 the Kingsbridge road, in the tavern-yard, is a 

 detached rock of Gneiss cleft in two pieces lying 

 side by side, and on the top of the Gneiss rock 

 which lies in place, the striae of this removed 

 rock, cross at right angles, the rock in place 

 below — it is as much as thirty feet long, the two 

 pieces together, being about nine feet broad and 

 ten feet high. 



In the valley, between Forts Washington and 

 George, on the Kingsbridge road, and on the left 

 side, there are a vast number of detached pieces 

 of Gneiss rock, which have evidently been pre- 

 cipitated from the cliff above, which forms the hill 

 of Fort Washington. The largest of all the boul- 

 ders on the island, is the one which stood on a 

 bare Gneiss rock at Depeyster's place, on the 

 east side of the Kingsbridge road, where it is 

 now crossed by 106th Street, and near the six 

 mile stone. There was also a boulder, or rath- 

 er large piece of rock, (which had been detached, 



