GEOLOGY OF OGDENSBURG 49 



It was our hope that, by carrying our work down the river below 

 Ogdensburg, this section could be extended upward. In this re- 

 spect we were completely disappointed. The drift is so heavy 

 below Ogdensburg, and the outcrops so rare and so poor that, with 

 the lithologic similarity of the beds, no certainty as to their position 

 could be arrived at. The best section seen east of Ogdensburg is 

 at Red Mills, 6 miles farther down the river, where a 20 foot thick- 

 ness is exposed, the basal layer appearing in the river bed and caus- 

 ing the Galop rapids in the river. The section here is : 



Four solid layers of blue, finely granular dolomite, 



10. 4' 8" weathering on edges in horizontal, wavy lines ; small cal- 



cite nodules ; much coarser grained than the beds below. 



, Q,, Blue-gray, hard, flinty dolomite, thin-bedded, upper 

 9- l 2 inches very shaly. 



, Two beds of massive dolomite, otherwise like that 

 8 - 2 4 above. 



Light-gray, hard, very finely granular dolomite, with 

 7. 2! i " small drusy cavities containing calcite ; weathers drab ; 

 two beds. 



i' 6" Unexposed. 



6. i' 3" Light-gray, flinty dolomite, excessively fine grained. 



Dark-blue, flinty dolomite, of very fine grain, in 6 inch 

 ' 3 4 layers. 



Gray, fine-grained dolomite, weathering yellow- 

 IO brown; irregular surface. 



, Hard, dark-blue dolomite, like no. 5 ; finer grained 

 ' l l than no. 4. 



2. i' Unexposed. 



, Single layer of thick, hard, very finely granular, gray 

 dolomite at river edge and in river ; base not seen. 



20' 10" total thickness. 



