592 ROLLIN D. SALISBURY 
It should be noted that the deformations of this time were more 
important in affecting the height of the land than in.affecting its area. 
Yet from the evidence of existing floras and faunas, it seems probable 
that the up-swelling of the contiguous parts of America and Asia were 
sufficient to connect them by way of the Aleutian Islands. Shaler 
and Spencer have urged reasons for thinking that Florida and Cuba 
were connected in the late Pliocene or early Pleistocene, but this con- 
clusion cannot be said to be established. In Europe, within the same 
general period of time, England has probably been joined to the con- 
tinent, and southern Europe to Africa. Submerged valleys on the 
northwestern coast of Europe, if interpreted in the usual way, indicate 
elevations several hundred to a few thousand feet greater than those 
of the present, enough, if some of the estimates are correct, to have 
connected Europe with Greenland and North America. If such a 
connection existed, it must have entailed changes in oceanic circula- 
tion sufficient to have affected the climates of high latitudes in an 
important way. 
The very considerable changes at the beginning of the Quaternary 
were followed by a great succession of changes as the period pro- 
gressed. Some of them reinforced the changes just sketched, and 
some of them were of the opposite phase. Oscillations of level 
during the Quaternary have been more carefully worked out along 
the coast of northern Europe than in America. Unexpectedly enough, 
evidence seems to point to greater depression during the glacial epochs 
than during the interglacial. ‘The amount of the determined oscilla- 
tions of level during the Quaternary range from a few feet to a few 
hundred feet. 
Il. EFFECTS OF PHYSIOGRAPHIC CHANGES ON CLIMATE 
In many parts of the earth, as in the interior and eastern part of 
North America, in Europe, and elsewhere, the increase of elevation 
at the end of the Tertiary was probably not sufficient to be of great 
importance climatically, in a direct way. In other regions, as in the 
western part of North America, on the other hand, the gain in height 
was probably sufficient to produce considerable effects directly. 
In an indirect way, the effect of the increase of average altitude 
of land on climate may have been much more considerable. Erosion 
