A GEOLOGICAL HISTORY. 61 



that fortification ; it is very similar to its brother 

 rocks at Stoney Point; veins of Talc, Quartz 

 and Carbonate of Iron run through this rock. 



4th Graywacke. — (See plate 6, fig. 4.) There 

 were many rocks called Graywacke by the older 

 Geologists, the one which I have retained this 

 name for, is a slaty conglomerate of pebbles and 

 sand, cemented together, by a silicious cement, 

 and without fossils. There are four or more 

 distinct varieties of this rock on this Island, the 

 most curious of which, are seen at the bluff that 

 separates Easton's beach from Sachuest, at the 

 south end of the Island ; at this locality all the 

 varieties may be seen, from the fine grain slaty 

 sandstone or grit, to the coarse conglomerate ; at 

 this locality also, one variety has pebbles of a 

 somewhat ovate form, which lie all in one direction, 

 that is, they are longer than broad and lie side by 

 side, and do not cross each other. Some varieties 

 of this Graywacke run into the shale above it, and 

 are so similar in appearance that they are diffi- 

 cult to distinguish. The kind used to make tomb- 

 stones of, is an argillaceous slate, it is quarried 

 near the Granite on the west side of " the Neck" 

 near " Hog-hole." 



