854 NEW YORK STATE MUSEUM 



supply of the city of Troy is affording a section rather more than 

 1 mile in length through the shale region north of the Tom- 

 hannock river and, by the courtesy of Prof. W. G. Raymond, 

 engineer in charge of these operations, we have been permitted 

 to examine the section in all its parts in great detail as the rock 

 is taken out. This section has already furnished some fossils 

 which indicate the geologic age of the shales through which it 

 runs; but, for the most part, the rock section has proved there, 

 as usual in most exposures of the eastern Hudson river shales, 

 comparatively devoid of these conclusive evidences as to its 

 geologic age. 



The discovery of a profuse graptolite fauna at the Deep kill, 

 Rensselaer co. as noted in my last report, wherein are repre- 

 sented the three zones of the Phyllograptus shales of Europe 

 or the lowest part of the Lower Siluric, has suggested the pos- 

 sibility of producing a map of that region on which may be 

 distinguished all the graptolite bands of the Lower Siluric shale 

 facies. During the present season investigation toward this end 

 has covered the southeastern part of the Cohoes topographic 

 sheet, with the Hudson and Hoosic rivers as western and north- 

 ern boundaries respectively. 



A discovery of considerable importance for the correlation of 

 the shales throughout this region was made incidentally in the 

 finding, in the vicinity of Schaghticoke, of the horizon of the 

 fossil Dictyonema flabelliforme with associated 

 species, all of which are regarded as indicating throughout 

 northern Europe, and wherever found, the top of the Cambric 

 series. This horizon has not before been found within the United 

 States. This is a distinct contribution to the faunas heretofore 

 represented in the New York series. 



The areal map of the Tully quadrangle. The work on this quad- 

 rangle was virtually done during the previous season; but it 

 seemed, on careful revision of the map prepared, that the strati- 

 graphic divisions were insufficiently detailed, and, to carry out 

 a more minute subdivision of the strata based more specially 

 on paleontologic evidence, the work has been reviewed and 

 is now brought to a satisfactory completion. 



Work on the Elmira quadrangle; cooperation with the United 

 States Geological Survey. Under the same conditions as have 



