336 W. Hopkins on Changes of Climate. 
elevated tract. Of such characteristic phenomena not the slight- 
est traces have been recognized. If it be urged that the eleva- 
tion might be more local than here supposed, I would reply that 
such an hypothesis would rather strengthen than weaken the ob- 
jection: for the more local the elevation, the more certainly, I 
think, would it be accompanied with dislocations which cou 
not escape detection. I should reject without hesitation any the- 
ory founded on the hypothesis of an elevation during the glacial 
period, at all approximating to that which would be necessary to 
produce the required degree of cold. 
81, Again, a great degree of cold might be produced by the 
conversion of a sufficient portion of the Atlantic into dry land, 
But this would also require an elevation of western Europe, prob- 
ably of several thousand feet ($ 25, p. 254). Now if the cold of the 
glacial epoch were thus produced, this enormous area of the At- 
lantic must have been uplifted from its former level immediately 
previous to that epoch, and must since have again subsided, 
Considering the probable depth of the Atlantic Ocean, this move- 
ment must indeed have been enormous, and yet, although occut- 
ring at the most recent geological period, not a trace of it is 0 
servable either on the European or American side of the Atlantic. 
Under any circumstances, a theory founded on such an hypothe- 
sis, would, I think, be most unsatisfactory, and cannot be accept- 
ed in opposition to any other theory which may be free from ob- 
jJections of so grave a character. : 
We may also observe, that any theory of the production of 
cold solely by the elevation of the regions presenting glacial phe- 
nomena would be insufficient to account for many of these phe- 
nomena. It would be necessary that such a theory should em- 
brace also the depression of such regions beneath the level of the 
sea, either before or after their elevation, for some of the phenom 
ena in question may be referred to floating ice and currents: 
water with quite as much certainty as others can be to the action 
of glaciers. f 
-82. Again, I have shown that the requisite degree of cold for 
the production of glaciers might arise from the diversion of the 
Gulf-stream into some other channel, the submergence of 4 great 
fromthe north. This diversion of the Gulf-stream igo 
produced by the elevation of a portion of the bed of the, Allan- 
rt therefore liable to the same ohjnenen ' 
which may be made against the supposition of the more HO 
portion of the Atlantic having been elevated into dry land dunpé 
