ii8 The American Geologist. February, i904. 
At the same time the more recent determinations of the solar 
constant and of the absorbing and trapping powers of the 
atmosphere, and its several constituents, have been made full 
use of. 
Objections have been raised against Mr. Manson's hypoth- 
esis, some of which may be mentioned, viz : 
1. Glacial conditions alternate from pole to pole instead 
of being uniformly distributed and cotemporary north and 
south of the equator. To this, Mr. Manson replies, or might re- 
ply : that it is not proven that the poles are alternately glaci- 
ated. The present shows rather that both polar regions are 
glaciated. The somewhat greater approach toward sea-level of 
glaciers in the southern hemisphere than those of equal latitude 
in the northern hemisphere can be attributed to the low specific 
heat of greater land areas in the northern hemisphere, com- 
pared with the higher specific heat of greater ocean areas in 
the southern hemisphere. 
2. The hypothesis assumes that elevated areas have been 
everywhere glaciated, even within the tropics. Whereas it is 
widely known that there is a district morainal belt crossing 
North America from New England to British Columbia that 
marks the limit of continental ice-movement, from the belt of 
north temperate rains, and that a corresponding, but less defi- 
nitely marked, belt, crosses about latitude 65° N. 
It is replied that the morainal belt and other older belts, 
have outer fringes, so-called, which mark earlier, greater ex- 
tension, and that authorities are not agreed as to the non-glaci- 
ation of the tropical zone. Throughout much of the great plains 
of the west, in Utah, Nevada and southern California, are grav- 
els and tills and terraces identical in composition and in struc- 
tural pose with glacial formations that lie north of the great 
morainal belt. Such formations were not, probably, connected 
with an ice-sheet that had a sweep of continental extent, form- 
ing a continental moraine, but they may have been deposited 
by, or at least due to ice-accumulations that were locally even 
thicker than the well-known continental sheet. Such deposits 
can be traced, though with feebler manifestations, much fur- 
ther south, and have been described even in tropical latitudes, 
and referred to the ice age. Until much more is known of the 
Quaternary in southern latitudes, it can hardly be held ad- 
