GEOLOGY OF THE VICINITY OP LITTLE FALLS 55 



ingly improbable that, in going the 12 miles farther west to Utica, 

 any such thickness of Potsdam as 300 feet could have crept in 

 in the interval. On the other hand, the great thickness of non- 

 calcareous layers which Prosser has included in the Beekman- 

 town in the Rome well, would seem to the writer to indicate that 

 some Potsdam might be present, both at Rome and at Utica. 

 The reference of 285 feet thickness of noncalcareous sandstones 

 to the Beekmantown seems to the writer hardly justifiable. Orton 

 has classed the 475 feet of rock between the Trenton and the 

 pre-Cambrian in the Rome well as Potsdam and Beekmantown 

 (Calciferous), without attempting to draw any line between the 

 two, and this would seem all that we may do safely at present, 

 though there is unquestionably some justification for Prosser 's 

 argument, based on the rock thickness, 475 feet being closely the 

 thickness of the Beekmantown at Ilion and Little Falls. If it 

 be all Beekmantown at Rome, the formation has undergone a 

 pronounced lithologic change in the interval. 



The Oswego county Avells, though many miles distant to the 

 northwest (Pulaski is nearly 40 miles -from Utica in that direc- 

 tion), seem to give significant evidence in this connection. Prof. 

 Orton reports 156 .feet of sandstone which he calls Potsdam, in 

 the Central Square well between the limestones and the pre- 

 Cambrian; also a 50 foot thickness of similar sandstone in the 

 Parish well. In the Pulaski wells he reports from 40 to 90 feet 

 of rock thickness between the Beekmantown and the pre-Cam- 

 brian, the general section being 



Beekmantown 



Greenish sand 10-40 feet 



Black limestone 20-40 feet 



Greenish sand 5-10 feet 



Pre-Cambrian 



In the Stillwater well there are similar sands with limestone 

 lying on the pre-Cambrian, the limestone being 6 feet thick, with 

 18 feet of calcareous sandstone below and 25 feet of green and 

 white sandstone above. Fossil fragments occur in the limestone 



