GEOLOGY OF THE NORTHERN ADIRONDACK REGION 



383 



youngest of the Paleozoic forma lions there exposed, it is likely 

 that do considerable thickness of any younger deposit was ever 

 laid down on dt, and hence it has been largely removed by 

 erosion, more so than any of the others, so that its summit 

 nowhere appears. The question is made more complicated by 

 tlif faulted character of the region and by the fact that the dis 

 tin bancus here have folded and cleaved the Utica more than they 

 have any of the subjacent rocks. White reports the formation 

 as having a thickness of several hundred feet throughout the 

 valley, but, in making this statement, includes the Cumberland 

 head rocks, whose fauna he elsewhere states to be a transition 

 one. 1 If they are to be included, the writer's estimate, based on 

 work in the same region, would coincide. A few miles east of 

 the lake shore in A^ermont, Brainard and Seeley at Shorehain, 

 and Walcott at Highgate Springs, have dnferentially indicated a 

 large thickness for these shales by calling their upper portion 

 Hudson River, instead of Utica. The deposits at the latter 

 locality would seem however to belong to the Levis, rather than 

 to the Chazy basin. In the discussion of White's paper. Ami 

 urged that the Utica about Ottawa is but 75 feet in thickness; 

 and it may well be that its thickness in the Champlain valley has 

 been overestimated. Adequate notions concerning the actual 

 amount .are not to be had as yet. So far as New York is con- 

 cerned, the fauna of the Cumberland head shales seems to be 

 confined to the lower Champlain region. 



In the Mohawk valley we meet for the first time with overly- 

 ing formations, so that the Utica summit is exposed, and definite 

 evidence in regard to its thickness can be obtained. Cumings 

 has shown, in eastern Montgomery county, a thickness of the 

 Utica of from 1000 to 1200 feet. 2 Thence westward to Little 

 Falls no measured sections have been carried through the 

 formation, so far as the writer is aware. South of the Mohawk, 

 near Little Falls, the writer has measured over 600 feet of the 

 formation, without reaching its summit. Walcott gives 710 

 feet as the thickness shown in the Campbell well, near Utica. 3 

 These go to show that the thickness in the Mohawk valley is 



1 Geol. Soc. Am. Bui. 10 :456-57. 

 *N. Y. State Mus. Bui. 34, p.466. 



s Geol. Soc. Am. Bui. 1 :347. 



