﻿438 LP. Bishop — Fossiliferous Limestones in Chatham, N. Y. 



can be proved, both by strias and the transport of erratics, that 

 the ice advanced on to the land from out of the sea. The 

 shells on Three Eock Mountain, near Dublin, and in North 

 Wales and Macclesfield, all from the Irish Sea ; the shells 

 in Cumberland transported from Sol way Firth ; those on 

 the coast of Northumberland brought out of the North Sea; 

 those of Airdree in Scotland, carried eastward from the bottom 

 of the Clyde : and those from Caithness from Moray Firth were 

 among examples adduced in proof of this principle. The im- 

 probability of a great submergence not leaving corresponding 

 deposits in other parts of England was dwelt upon. 



It was also held that there was insufficient evidence of more 

 than one advance in the ice sheet, although halts occurred in 

 its retreat. The idea of successive elevations and submergen- 

 ces with advances and retreats of the ice was disputed, and the 

 author held that much of the supposed interglacial drift was 

 due to subglacial water from the melting ice. 



The last portion of the paper discussed the distribution of 

 bowlders, gravels and clays, south of the glacial area. Much 

 the greater part of England was believed to have been uncovered 

 by land ice. The drift deposits in this area were shown to be 

 the result in part of great fresh- water streams issuing from the 

 melting ice sheet v and in part, of marine currents bearing icebergs 

 during a submergence of some 450 feet. The supposed glacial 

 drift about Birmingham, and the concentration of bowlders at 

 Wolverhampton were regarded as due to the former agent, 

 while the deposits at Cromer and the distribution of Lincoln- 

 shire chalk across southern England were due to the latter. 

 The supposed esker at Hunstonton was held to be simply a 

 sea-beach, and the London drift deposits to be of aqueous 

 origin. Thus the rival theories of floating icebergs and of land 

 glaciers were both true, the one for middle and southern Eng- 

 land, the other for Scotland, Wales, and the north of England ; 

 and the line of demarcation was fixed by great terminal 

 moraines. 



The paper closed with an acknowledgment of indebtedness 

 to the many geologists in England and Ireland who had ren- 

 dered most generous assistance during the above investigation. 



Art. LI. — On certain fossiliferous Limestones of Columbia Co., 

 N. Y, and their relation to the Hudson Piuer Shales and the 

 Laconic System ; by I. P. I Bishop. 



The age of the Taconic formation is a subject of so great 

 geological interest that I need no other apology for the presen- 

 tation of this paper on new discoveries of fossils in a metamor- 



