GEOLOGY OF THE REMSEN QUADRANGLE 39 



formation'^across country might well be considered. From the 

 lithologic standpoint the most striking difference comes from a 

 comparison of the upper Trenton on the one hand with the Dolge- 

 ville on the other. The removal of the thin mass of coarse crystal- 

 line limestone from the Trenton Falls section and an increase in 

 thickness of the shale partings in the rest of the upper Trenton 

 there would result in a formation like that of the Dolgeville shales. 

 Such a change could have been effected by comparatively small 

 differences in conditions of deposition. This argument comes to 

 one with special force while looking at the thick mass of thin 

 bedded limestones with pronounced shale partings just beneath 

 the coarse crystalline limestone at Trenton Falls. The presence 

 of the pure coarse crystalline limestones around Trenton Falls 

 signifies clearer water conditions and the sharp contact with the 

 Utica shales signifies the sudden advent of muddy water, 

 although the sharpness of the contact is somewhat modified by 

 the calcareous character of the lower shale beds. In the vicinity 

 of Little Falls the transition from limestone to shale was more 

 gradual. Thus we see that the upper Trenton of Trenton Falls is 

 in all likelihood to be correlated with the Dolgeville of the Little 

 Falls section; that these correlated portions are lithologically not 

 greatly different; and that comparatively slight changes in the 

 conditions of deposition readily account for the absence of the 

 Dolgeville shales in the Trenton Falls district. 



Minor evidences to show local changes in sedimentation in the 

 lower part of the Trenton formation near Little Falls are to be 

 found in the only occasional presence of the Black River beds and 

 the great variations in thickness of the Lowville. 



GLACIAL GEOLOGY 



In the Trenton Falls district there is abundant evidence to 

 prove the former presence of the Post-tertiary ice sheet. The evi- 

 dence consists chiefly in the glacial drift such as the till, morainic de- 

 posits, and the general sand and gravel deposits which are so widely 

 scattered over the Remsen quadrangle. Sometimes large areas 

 are so thoroughly drift covered that the underlying formations 

 are completely concealed from view. The heaviest accumulation 

 of drift appears to be over a broad area extending from southeast 

 to northwest across the map. In this area scarcely an exposure 

 can be found except here and there along the stream courses where 

 the drift has been worn through. 



