WARREN COUNTY. 



179 



therefore, tliis rock is unimportant, so far as it is a depository of useful substances. As a 

 rock, however, it may be employed as has been suggested above ; and probably, under favora- 

 ble circumstances, more extensively than I have intimated here, as it is, when easily pul- 

 verized, adapted to glass-making, furnishing a sharp-gritted sand for sawing marble, and for 

 sand paper. 



Calciferous Sandrock. 



This rock may be observed at numerous places in this county. The rock which forms 

 Diamond island in Lake George, is a good example, and is the usual form under which it 

 appears. There are, however, several varieties of this mass, and still they possess many 

 characters in common. It is, as would be inferred from its name, a compound rock com- 

 posed of lime and sandstone or silex. About one mile northeast from the village of Glen's- 

 Falls, it appears as an outcropping mass ; it occurs at numerous places, at some of which it 

 has been quarried for the canal locks and other purposes. It is an excellent stone for dura- 

 bility ; and as the beds or layers are generally thick, there is no difficulty in procuring them 

 of a large size. 



This rock appears also below the falls ; it forms the mass beneath the beds of marble, and 

 may easily be recognized by the drab-colored layers which appear near the water's edge. 

 Many of tiiese layers might be employed for water-lime, as tliey are evidently impure lime- 

 stones, and indicate, from the manner in which they weather, the composition required for 

 hydraulic lime. 



Some obscure univalves, together with a few other shells, may be found in the calciferous 

 sandrock northeast of the falls, and are represented in the following cut. They are not abun- 

 dant fossils, but have a wide distribution ; and so far as observation has yet been extended, 

 they liave not been found in the rocks above. 



53. 



No. % Ophileta complanata. 



No. 1. O. levata. This fossil I did not observe, though it belongs to this rock. 



No. 3, is a plate of the head of an encrinite, very abundant in the upper part of the calciferous at Chazy. 



No. 4, is the Orthoceras primigenius, a small species, found near the bridge at Fort-Plain. 



