8 BULLETIN OF THE LABORATORIES 



and likewise the Salamanca layer with the Lackawaxan pudding- 

 stone, thus making the two layers continuous over southwestern New 

 York, across eastern Pennsylvania on a line rudely parallel with the 

 Blue ridge into southwestern Virginia. In the Catskill mountains a 

 layer of conglomerate is present which may be equivalent to one of 

 these layers. It seems quite natural that the conditions attending the 

 formation of the Hamilton group again operated to a lesser extent 

 during the upbuilding of the Neodevonian. It cannot be denied that 

 the lower Chemung was restricted in its basin to the northward, while 

 in its limited extension east of the Hudson the highlands of New 

 England may have furnished material for its upbuilding. In 

 Ohio rather abruptly limited on the west by the Cincinnati 

 uplift, the strata were deposited in a sea whose main axis ran 

 north and south, and which received its sediment from currents di- 

 rected northward. It may possibly be that the hiatus existing in Vir- 

 ginia between the Archaean and Tertiary went to supply part of this 

 material, while it is natural to conceive that strata now only repre- 

 sented by the West Indies may have not only sent its contribution to 

 this formation but still others in the geological scale. But of that 

 nothing can be said with certainty. The effect of tidal currents is 

 essential in producing such beds of conglomerates as have been laid 

 down during this age, and in the flat and round pebbles of the Panama 

 and Salamanca conglomerates, we have illustrated the active erosive 

 in shallow waters, with the result of somewhat different physical 

 environments. 



Although somewhat intimately related in the eastern extension of 

 its basin with its underlying rocks the deposition of the Waverly 

 shales in Ohio witnessed an important change in the physical geogra- 

 phy of the lower Carboniferous formation. On the northwest there 

 was a close connection with the Marshall group in Michigan, and 

 even after the Berea and Cuyahoga shales had been uplifted in north- 

 eastern Ohio the channel remained open at least until the middle 

 Waverly freestones had begun to be deposited farther south, probably 

 receiving accessions for growth from the Cincinnati geanticline, but 

 the physical conditions for faunal existence farther south toward 

 the Ohio river were not favorable at the close of the lower first divis- 

 ion of the Waverly. East and northeast from central Ohio, the con- 

 ditions attending the deposition of the middle and upper Waverly 

 were apparently more favorable under the coal bearing formations 



