454 PROCEEDINGS OF THE NEW YORK MEETING 



added to our information of the distribution of each of the formations witliin the 

 Cliamplain valley, and extended the detailed stratigraphic study of the lower mem- 

 bers of the formations there so extensively developed. 



Scope of the Investigation 



As above cited, the detailed stratigraphy of the Cambrian, especially in the 

 northern part of the Champlain valley, has been published by Mr Walcott, while 

 similar work has been done in subdividing the zones of the Calciferous and Chazy 

 in the region by Messrs Brainerd and Seely. My endeavoi' has been to prepare 

 a similar preliminary study of the detailed stratigraphy of the Birdseye, Black 

 River, and Utica formations overlying the latter. 



The method of investigation employed was modeled on that developed by Pro- 

 fessor H. S. Williams in his studies of the Devonian of western New York* and 

 which has been described elsewhere by the writer.f Each stratigraphic zone which 

 differed in anywise from those adjoining it was analyzed, on a faunal basis, and 

 kept separate through all subsequent laboratory examination. The mass of the 

 detailed work as thus analyzed will be published in volume xiii of the Annals of 

 the New York Academy of Sciences, and the present contribution is but a sum- 

 mary of results therein set forth. In some cases as many as 96 distinctive beds 

 were recognized and differentiated by reason of faunal or lithologic differences 

 within the limits of a section having a total thickness of less than 200 feet. 



General Relations of the sedimentary Rocks of the Region 



From Fort Ticonderoga to the head of Missisquoi bay, lake Champlain is about 

 110 miles long, and its greatest width is 13 miles. The lower Cambrian is unknown 

 on the western side of the lake, but on the eastern has a thickness of many thou- 

 sand feet. The Calciferous has a thickness of possibly over 1,200 feet, and the 

 Chazy perhaps half that. Following this very considerable mass of deposits, the 

 upper Ordovician beds were laid down, more or less conformably, and all have sub- 

 sequently undergone not only profound faulting into great blocks, but also local 

 dislocation. 



The Birdseye is not clearly recognizable in the Champlain valle}' itself. Most of 

 the localities and fossils once referred to it in the district are now known to belong 

 to the Calciferous and Chazy. In Benson an outcrop 6 feet thick occurs which 

 contains true Tetrudium ceUidosum (Hall). 



Outliers and embayments of the Potsdam and Calciferous are known at an 

 altitude of over 1,000 feet above the lake level, in the midst of the Adirondacks, 

 isolated from tiie main outcrops, and showing no higher sti-ata above them. J 



Character of the Deposits 



The lowest bed of the Black River, wherever a complete section is exposed, is a 

 very compact and tough dove-gray limestone, having a conchoidal fracture, and 

 in appearance somewhat resembling the true Birdseye. but usually containing 

 no fossils other than ostracods. The capping bed of the underlying Chazy, where 



*H. S. Williams : Bull. 41, U. S. Geological Survey, 1887. 



fT. G. White and G. van Ingen : Trans. New York .\cad. Sci., voL xv, 1395, pp. 19-23. 



t J. F. Kemp : Bull. Geol. See. Am., vol. 8, 1S9G, pp. 408-412. 



