128 
FOURTEENTH REPORT. 
had in mind it seems proper to include all of this as evidence pointing 
to the conclusion that all of these tropical lands stood in greater relief 
above the sea than they do now to the extent of 5.000 to 0.000 feet or 
even rather more. He is inclined toward the larger figures. 
BRITISH ISLES. 
Between the British Isles and northwestern Europe a land connection 
presumably Quaternary, is conceded by all. It may have existed through 
the greater portion of Tertiary time. The soundings in the surrounding 
waters together with the distribution of the freshwater fauna have 
yielded a fairly complete picture of the river systems that occupied 
the regions now covered by the English Channel to the south and the 
Irish Channel and Irish Sea on the west.* The fact, determined by 
Hull, that one of these drowned rivers where it crosses the edge of 
the continental shelf forms a very deep gorge indicates that the duration 
of Hie emergent state was of the same order of length as the others- of 
similar nature elsewhere, which is to say, it appears to have extended 
over a very large part of Tertiary time, much like the canon of the 
Colorado in North America.! 
Scharif has brought out numerous instances in which both animal 
and plant forms were able to survive the Glacial Epoch substantially in 
situ, in England and Ireland even forms like the Bristle Fern and many 
Portugese (“Lusitanian”) species which normally enjoy considerably 
milder climates than even that of Ireland today. Under older notions 
of the Glacial Period it was deemed impossible that there should have 
been any such survivals in the British Isles, but they are clearly there, 
Scandinavian. Lusitanian, Amercian and even South American forms 
which must have been there long before the Glacial Epoch and which, 
if they had been swept off by the ice. could not have returned. Here 
in America we have a similar set of facts, excepting that here they 
are far more complicated by reason of the greater area and consequent 
greater probability that forms swept off toward the south could and did 
return northward when the ice disappeared. $ Even here, in spite of 
Professor Gray's classical conclusions, it would afford relief from cer- 
tain puzzling questions if we could find a refuge along the Atlantic 
coast for the fluviatile animals which now occur in the eastern moun- 
tain streams. If is inconvenient, to say the least, to be compelled to 
crowd these animals out with the glacial ice and then afterward to 
get them all back again apparently as they were before. It would be 
a good deal easier to lengthen their rivers a bit and let them take 
refuge in the lower altitudes while the ice was at work upon the heights. 
This is precisely what seems to have occurred in the British Isles. 
There we are almost compelled to infer that during the Glacial Epoch 
there was a much greater altitude of the land above the sea than 
there is now and that the explanation of the persistence of warmth- 
loving preglacial forms of life lies in the refuge afforded by a broad 
*Scharff, R. F., “The History of the European Fauna.” Lond. 1889. 
“European Animals: Their Geological History and Geographical Distribution,” Lond. 1907. 
“On the Evidences of a Former Land-bridge between Northern Europe and North America,” 
Proc Roy. Irish Acad., vol. xxviii, Sec. B, No. 1, Dublin 1909. 
t Dutton, Clarence E., “Tertiary History of the Grand Canon District,” Monograph, U. S. Geolo g. 
Survey, 1882. 
jGray, Asa, “Forest Geography and Archaeology,” Am. Jour. Sci. and Arts, vol. xvi, 1878, p. 94 — , 
p. 183—. 
