34 NEW YORK STATE MUSEUM 



the specimen was afterward lost, the fact is given in the Manual 

 with a query as to the species.'' 



It is a noteworthy fact that in reviewing the works which have 

 been published relating to the Oneida conglomerate and specially 

 those which consider the Oneida as below the Medina, one can 

 scarcely find anywhere a reference which attempts to show or 

 even infer that Vanuxem's conclusion was not a correct one. It 

 is also not an easy task to show specifically how the Oneida 

 came finally to be regarded by geologists as lying below the 

 Medina. 



It should be mentioned, however, that the Shawangunk grit 

 was regarded by all the early geologists as the stratigraphic 

 equivalent of the Oneida conglomerate — a correlation which no 

 longer holds good, the two terms being used as synonyms. Since 

 we have red shales lying above the Shawangunk conglomerate, 

 the same condition may have been assumed for central New 

 York and thus the order of the beds determined. 



Again the overlapping of the upper part of the members of 

 the Ontaric system in central New York was formerly regarded 

 as a thinned portion of the whole formation and not of the upper 

 part alone as is now known to be the case. 



The critical section for the stratigraphic position of the Oneida 

 conglomerate is along the Oswego river. At the mouth of the 

 river and along the shore of Lake Ontario we find the typical 

 gray Oswego sandstone. Above the city and along the river 

 banks, one can see that above the Oswego sandstone we have the 

 red sandstones and shales of the Medina. These rocks show 

 at intervals, and are specially well shown 12 miles farther south 

 at the city of Fulton, at which place we have the falls of the 

 Oswego about 10 feet in hight. The fall is due to the resistant 

 character of the rocks and an examination shows that the rock 

 is a quite coarse conglomerate, in which the fossil Arthro- 

 phycus alleghaniensis is found in great abundance and in 

 a fine state of preservation. The rock above the fall can not be 

 observed but enough is known to show that the conglomerate 

 is not far below the Clinton formation. 



In New York, the fossil Arthrophycus alleghan- 

 iensis Harlan is found in the Oneida conglomerate near 

 Utica, at its type section in Oneida county, at the falls of the 

 Oswego, and in the upper Medina west to the Niagara river. 

 It is also found in Canada. Throughout this section this fossil 

 is practically limited to the upper portion of the Medina and is 

 thus important as an horizon marker. The presence of this 



