Clarke — Oneonta, Ithaca and Portage Groups. 



west of the village of Smyrna, though, as determined by Prosser, it can be 

 traced somewhat eastward beyond the vanishing point of the Tully limestone. 



Sherburne Sandstones. 



In adopting this term of Vanuxem's, I follow the suggestion of Pro- 

 fessor Prosser, who points out the fact that these beds of sandstones, flags 

 and sandy shales are continuous from the Chenango river westward at least 

 as far as the meridian of Cayuga lake. Their lithologic character together 

 with their notable paucity of fossils permits the identification of them still 

 farther westward. The heavier beds, lying at the base of the Portage series 

 in Seneca and Yates counties, indicate an extension of this division into more 

 westerly regions; but with the growing predominance of the typical Portage 

 or Naples fauna over that of the Ithaca group, the individual character of 

 the deposits here becomes gradually lost. In the region, however, between 

 the Tioughnioga and Chenango rivers, it is a well-defined formation, standing 

 in sharp contrast to the Tully and Genesee beds beneath and to the beds 

 immediately overlying, which contain the reappearing and modified fauna of 

 the Hamilton group. 



Ithaca Group (lower division). 



The rocks which are properly included within the Ithaca group of 

 Vanuxem are here represented in two colors, as there is, for this region 

 at least, a ready distinction in the faunas of the lower and upper beds. 

 From the detailed description of the sections of these strata given in the 

 following pages it is seen that the lower division, which is on the whole less 

 arenaceous than the upper, contains strongly developed faunal characters of 

 the Hamilton group, a fact clearly brought out by the observations of both 

 Professor Prosser and the writer at North Norwich, Norwich, South Otselic 

 and Pitcher Springs, in Chenango county. 



Thus at Stations A and B, of my preliminary paper, in the cast-west 

 section from Norwich toward Preston, are such characterizing species as 

 Phacops rami, ffomahnohis DeKayi, BeTkrophon patulus, Athyris spvri- 

 feroides, and Spvrifer cmdacuhts, in addition to which are many other species 

 of the Hamilton fauna which extend into the higher beds of the Ithaca forma- 

 tion. At South Otselic (Station III), these beds are admirably exposed. 

 Directly overlying the fucoidal layers of the Sherburne sandston.es are compact 

 dark shales with a small association of certain Hamilton species not abundantly 



