46 Ujpham — Mevievj of the Quaternary Era, 



from France and Great Britain to the Fseroe islands and thence 

 to Iceland and Greenland was uplifted to form a continuous 

 land surface, remaining thus so long as to be a bridge for the 

 migration of the European flora after the departure of the ice.* 

 On the whole, however, there was probably not less evapora- 

 tion from the sea, and not less precipitation from the clouds, 

 than now. Upon the most elevated areas the moisture received 

 from the clouds was temporarily stored as ice ; while in con- 

 tiguous mountain districts, as the southern Appalachians, the 

 excessive winter snows were each year melted and poured 

 down in floods across the plains between the mountains and 

 the ocean. And on the glaciated areas, when the ice-sheets 

 were at any time forced to retreat, and especially during their 

 final melting, great floods of water from the dissolving ice and 

 from accompanying rains swept down from the ice-surface, 

 filling the valleys of the adjoining land and spreading over its 

 plains in their seaward course. 



Unusually abundant detritus was supplied to the Quaternary 

 river floods, both on unglaciated areas and on tracts that had 

 been ice-covered. For example, our southern Appalachian 

 district had been subjected to very long continued subaerial 

 denudation under a more equable climate and at less altitude 

 during the Tertiary era, and a large amount of detritus rested 

 on the mountain slopes and in the high valleys, ready to be 

 earned away to the lower plains by the swollen rivers at times 

 of Quaternary uplifts of the continent and northern glaciation. 

 Within the ice-sheets, too, much drift was gathered up from 

 the general land surface over which the ice slowly moved out- 

 ward from its central area ; and especially the sides of hills 

 and mountains, rasped by the overriding ice, yielded plentiful 

 bowlders and coarse and fine rock-debris, which was borne 

 forward as englacial drift, to become part of the ground mo- 

 raine farther on, or to be dumped in the terminal moraines, or, 

 not reaching these, to be exposed on the surface of the ice 

 during its departure. The osars and kames, and the abundant 

 stratified drift of valleys and plains in glaciated countries, 

 show that the amount of englacial drift was large, and that 

 much of it was carried off to form these deposits by the flooded 

 rivers that descended from the melting ice. 



Attempting a correlation of the Quaternary fluvial deposits 

 of this country, we may notice first those which were formed 

 upon areas beyond the limits of the glacial drift. In the 

 southern Atlantic states the Appomattox and Columbia forma- 

 tions, described by Mr. McGee as marine beds, characterized 

 by coarse cobble and gravel deposits, with ice-borne bowlders, 



* Andrew Murray, Geographical Distribution of Mammals, 1866, pp. 37-42. 

 James Geikie, Prehistoric Europe, 1881, pp. 518-522, and p. 568, with plate E. 



