Ch. XV.] THEORY OF A MIOCENE ATLANTIS. 273 



range in the central parts from two to three miles. To suppose that 

 a continent, therefore, was so situated up to the close of the Miocene 

 period, when the American types, as seen at (Eningen, were most 

 dominant, would imply a prodigious amount of subsidence in a com- 

 paratively brief period. In the lifetime of a single generation of men, 

 plants, of which the seeds have been unintentionally transported to a 

 distant coast, have made their way for many miles into the interior 

 without human aid. A botanist, therefore, might form some rude 

 estimate of the number of centuries which would be required for an 

 assemblage of plants to spread over land several thousand miles in ex- 

 tent from east to west ; but no geologist would venture to estimate 

 the ages required to convert so many thousand miles of land into a 

 shallow sea and then turn that vast shoal into a sea-bottom two or 

 three miles deep. 



Even if we were called upon to imagine that the Miocene flora origi- 

 nated in the Southern United States, in Georgia and the Carolinas for 

 example, and that they made their way overland westward for a 

 distance of 16,000 miles to Europe, we might conceive such a migra- 

 tion to be performed in a mere fraction of the period which it would 

 take to convert Africa or North America into an ocean as deep as the 

 Atlantic. 



Behring's Straits do not exceed in depth and width the Straits of Do- 

 ver, so that the former union of North America with Asia would demand 

 only a slight change of level, and the present existence of such chains 

 of islands as the Kurile and Aleutian makes it easy to imagine that 

 there may have been a post-miocene connection between Kamt- 

 sckatka, Japan, and China. Independently, therefore, of the botanical 

 arguments in favor of a migration from east to west, this latter theory 

 involves us in far less hazardous speculations as to geographical change 

 than that of a Miocene Atlantis. 



We are not, however, entitled to take for granted that some of the 

 American types may not have crossed to Europe in high Northern 

 latitudes, when Greenland, Iceland, and the Hebrides were united by 

 a continuous land communication. And in support of this view it 

 may be urged that a Miocene flora has been discovered in several parts 

 of the Arctic lands, especially in Disco Island, in Greenland, lat. 

 70° N., and in Iceland, and, as above mentioned, p. 242, in the 

 Island of Mull in the Hebrides. But in the first place, in reference 

 to these northern miocene deposits, it may be observed that palms 

 and other tropical forms are wanting; and secondly, the depth of 

 the ocean in the regions alluded to is very great. Sir L. Mac- 

 Clintock, when sounding for the proposed submarine telegraph, found 

 a depth of 4092 feet between Scotland and Iceland, and again a depth 

 of no less than 9432 feet between Iceland and Greenland. Possibly 

 the number of fathoms might not be so great if a survey of the Arctic 

 Seas were made in a still more north-westerly direction from Iceland 

 to Greenland, but we have no data at present which favor this notion. 

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