10 BERRY— A POSSIBLE EXPLANATION 



favorable conditions of situation with respect to warm ocean currents. 

 This is a difference of ii degrees. The flora of the Jackson was, 

 moreover, a coastal flora, and I have not the slightest doubt but that 

 had the Mississippi embayment extended five degrees farther North, 

 its shores would have been clothed with the same Jackson flora, for 

 at that time similar floras are found in the Paris Basin in Latitude 49° 

 North, in southern England in Latitude 51° North, and along the 

 expanded Mediterranean sea of the Old World. 



The southern limit of the contemporaneous " Arctic flora " is 

 about Latitude 45° North in North America (British Columbia), and 

 about 57° North in Europe (Isle of Mull). It seems to me that the 

 essential concordance of these facts is significant, and whatever may 

 be thought of them, it would certainly seem to be difficult for any one 

 to claim that these various Eocene floras mentioned do not show a 

 climatic change in passing northward from the equator toward the 

 pole. Moreover, at present — a time of, in many ways, an abnormal 

 climate in a geologic sense; with rather sharp zoning, although not 

 nearly so sharp as the textbooks would have us believe; a time of 

 almost, if not quite, unprecedented land expansion in the Northern 

 Hemisphere — which I believe expresses a causal relationship ; the 

 reliable members of these Eocene Arctic floras range much farther 

 southward than they did in late Eocene time. 



That changes in the geographic distribution of land and water 

 might prove sufficient to account for these Eocene Arctic floras is 

 suggested by the climatic influence of the northward drift of warm 

 water in the North Atlantic at the present time ; which influence in 

 western Europe and Spitzbergen is a trite fact, familiar to all. If 

 the reader will consult an Isothermal map, and will compare the North 

 Atlantic region with that of Behring Strait, or with the center of 

 Siberia (the latter the present location of the cold pole), the combined 

 influence of the northward drift of warm oceanic water from lower 

 latitudes, and the influence of the relative amounts and geographic 

 position of lands and seas, is seen to be most astonishing. 



For example, the January isotherm of — 25° C, which is at 

 Behring Strait, is 18 degrees farther North in Baffin Bay, and reaches 

 to the pole itself North of Spitzbergen. The July isotherm of 5° C. 

 (41° F.), which is at Behring Strait, swings 10 degrees farther North 



