56 NEW YORK STATE MUSEUM 



equivalent of the Oneida conglomerate of central New York, its age 

 was assumed to be Clinton. Recent investigations by Ulrich and 

 Schuchert/ and by Hartnagel, have shown that the formation in 

 question is of late Siluric age, the former authors regarding it as a 

 part of the Cobleskill and including it within the Manlius series, 

 while Hartnagel, Clarke and others regard it of Salina age. As 

 will be shown presently, it is probably the partial equivalent of the 

 lower cement bed of Rosendale which in turn represents a part, 

 but probably not a whole, of the Bertie waterlime series of western 

 New York. 



It is seen from this discussion that the Brayman shales rapidly 

 disappear eastward and that they have been correlated with the 

 Salina on account of their position below the Cobleskill limestone. 

 Grabau has argued that the Brayman is more closely united with 

 the underlying sandstone of the " Lorraine " beds than with the 

 overlying Cobleskill limestone. For that reason, he would transfer 

 these sandstones into the Upper Siluric (Salina) age,^ expecting 

 to find the unconformable contact with the " Lorraine " beds below 

 them. We have, however, pointed out in the description of the Cen- 

 tral Bridge section, that the eurypterids of the Schenectady shale 

 continue into the lower part of this sandstone, and that the sand- 

 stone beds of the top of the Schenectady shale in that section are 

 also united with the Brayman shale by their pyrite nodules, exactly 

 as in Mix and O'Reilly's quarry at Schoharie (Grabau, page 103). 

 One would, from this evidence, rather infer that the top sandstone 

 of the " Lorraine" (Schenectady) shale, by its close relationship to 

 the Brayman shale, draws the latter into the Lower Siluric. No 

 fossils have been found in the Brayman shale and the formation 

 has not been directly traced eastward or westward into another 

 formation, thereby revealing its true age by direct evidence. 



We have therefore in the correlation of these shales to rely for 

 the present entirely on indirect evidence. 



In the attempt to trace the shale eastward along the foot of the 

 Helderberg escarpment outcrops fail outside the Schoharie recess in 

 the escarpment until the Indian Ladder and the New Salem sections 

 are reached, where 10 inches of " greenish sandstone to coarse 



1 Ulrich and Schuchert, in their " Seas and Barriers," accepted merely 

 previous determinations. R. 



2 Grabau follows here merely the general though unfounded assumption 

 of the Salina age of the Brayman shale. Assuming that the sandstone is 

 of Ordovicic age, the same line of arguments would show the Brayman 

 shale to be of Ordovicic and not of Salina age. 



