GEOLOGY OF THE REMSEN QUADRANGLE 33 



Pleistocene age along Black river to the north of Trenton Falls 

 and also along the Canal feeder west of Forestport. The latter 

 occurrence has been described and figured by Vanuxem.^ Regard- 

 ing this phenomenon Vanuxem says: " No cause can reasonably 

 be assigned but different degrees of lateral pressure." The folding 

 is often so great, however, that the required differences in degree 

 of lateral pressure are altogether too great. The writer believes 

 that, in principle, the explanation given for the contorted limestones 

 may apply here also, except in the case of the clay beds the move- 

 ment of upper over lower masses may have been caused by ice ac- 

 tion or by having been pulled down the hillside by gravity. Or as 

 Salisbury and Atwood^ have suggested for such a phenomenon in 

 Pleistocene clay, that the cause may have been lake ice or " the 

 grounding of an iceberg on the surface before the overlying layers 

 were deposited." In any case the cause of the movement in these 

 superficial clays is very different from that of the ancient Trenton 

 limestones. Such interbedded contortions are very common in the 

 Pleistocene clays of New York, especially along the Hudson river 

 valley. 



THE PALEOZOIC OVERLAP 



As already stated the Paleozoic rocks overlap upon the Pre- 

 cambric. This was caused by a gradual sinking of the Adirondack 

 region while Paleozoic deposition was going on, so that the younger 

 formations encroached farther and farther upon the sinking land 

 mass. 



Since the Potsdam sandstone nowhere outcrops along the south- 

 western border of the Adirondacks, any evidence for its presence 

 as the lowermost of these overlapping formations must be sought 

 for in deep well sections. This question has been clearly dis- 

 cussed by Professor Cushing who uses data furnished by both 

 Prosser and Orton.^ The writer here merely wishes to state the 

 general conclusion that in the Ilion, Utica and Rome wells the 

 presence of Potsdam sandstone has not been definitely proved 

 because of the difficulty in distinguishing Beekmantown and 

 Potsdam on the one hand and Potsdam and Precambric on the other. 

 Farther northward in certain Oswego county wells the presence 

 of the Potsdam has been demonstrated. Since the Potsdam does 

 not outcrop along the Precambric boundary line east of these wells 

 it is evident that younger formations overlap it upon the Pre- 

 cambric. 



1 op. cit. p. 214-15. 



'Jour. Geol. 1897. 5:14.3. 



•Geology of the Vicinity of Little Falls. N. Y. State Mus. Bui. 77. 1905. p. 51-5^. 



