loo llie AmericdH (re(>l<Hji.st. August, 1H<,5. 
ent siil)ject, to eiuiuire how far such a climate might be iii- 
iliicetl by the presence of an atmosphere in great part, or al- 
most entirely, com))osed of aqueous vapor. 
CORRELATIONS OF STAGES OF THE ICE AGE IN 
NORTH AMERICA AND EUROPE. 
By Wakeex Upham, Cleveland, Ohio. 
(Plates V and VI.) 
Exploration of the European terminal moraines and other 
drift deposits by two Americans, Prof. H. C'arvill Lewis in the 
British Isles, and Prof. R. I). Salisbury in Germany, less than 
ten years ago, laid the foundations for determining the geo- 
logic equivalency of the successive parts of the drift series in 
North America and Europe. Salisbui*y especially noted that 
the marginal moraines of northern Germany lie, as in the 
United States, at some distance back from the limits of the 
drift. 
Studies by many observers have shown that on both conti- 
nents the border of the drift along the greater part of its ex- 
tent was laid down as a gradually attenuated sheet; that the 
ice retreated and the drift underwent much subaerial erosion 
and denudation ; that renewed accumulation and growth of 
the ice-sheet, but mostly without extending to its earlier lim- 
its, were followed by a general depression of these burdened 
lands, after which the lee again retreated, apparently at a 
much faster rate than before, with great supplies of loess from 
the waters of its melting; that moderate re-elevation ensued, 
and that during the farther retreat of the ice-sheet prominent 
moraines were amassed in many irregular but roughly paral- 
lel belts, where the front at successive times paused or re-ad- 
vanced under secular variations in the prevailingly temperate 
and even warm climate by which, between the times of forma- 
tion of the moraines, the ice was rapidly melted away. 
Such likeness in the sequence of glacial conditions probabl}' 
implies contemi)oraneous stages in the glaciation of the two 
continents; and the present writer believes that it is rather 
to be interpreted as a series of phases in the work of a single 
ice-sheet on each area than as records of several separated 
and independent epochs of glaciation, ditfering widely from 
one another in their methods of depositing drift. The latter 
view, however, is held hj James Geikie, Penck, De Geer, and 
