THE GLACIAL PERIOD EAST AND WEST. 817 



5. As the above review of facts makes manifest, the division 

 among geologists on the question, and the differences in intensity 

 of opinion, are to a large extent geographical. 



The cause of this sectional divergence in views deserves con- 

 sideration. The writer has come to the conclusion that the cause 

 is largely 'meteorological : that the geological differences in opinion 

 are a consequence not only of differences in observed facts in the 

 West as compared with those of the East, but back of these, in 

 meteorological differences in the two regions during the Glacial 

 period. 



At the present time the glaciated areas of eastern and central 

 North America differ widely in hygrometric conditions. For 

 New England and three fourths of the State of New York the 

 mean annual precipitation, according to Schott's maps, varies 

 from thirty-eight to forty-two inches a broad coast region, nearly 

 half the breadth of New England, excepted over which it amounts 

 in some parts to fifty inches ; while for Wisconsin it varies from 

 thirty-two to thirty-eight inches, and for the larger part of Minne- 

 sota, from twenty to thirty-two inches. North of New England, 

 in British America east of Hudson Bay, the annual precipitation 

 is from thirty-two to twenty inches; but to the west of this 

 region, over Manitoba and beyond, it is twenty to ten inches. 



Here is a large present difference between the eastern and west- 

 ern regions, affecting snowfalls as well as rainfalls. 



Now, in the Glacial period, this eastern region would not only 

 have had the same great advantage as now of proximity to the 

 Atlantic Ocean, but also that of greater height than now. The 

 evidence appears to be conclusive that along the Atlantic side of 

 the continent from southern New England northward, as well as 

 on the Pacific side, the continent stood much above its present 

 level, and that the elevation was the culmination of that which 

 was in progress during the closing part of the Tertiary era as 

 urged by Prof. Upham. However much the surface of the great 

 medial valley of the continent was raised, it can not be reason- 

 ably questioned that the border mountain regions experienced the 

 greater amount of elevation. Hence, with the mountain condens- 

 ers on the east so much increased in altitude and extent, the dif- 

 ferences between the eastern and interior regions as to precipita- 

 tion would have been greatly augmented, to the advantage of the 

 eastern region. 



Further, the Glacial period was probably a time of greater pre- 

 cipitation than now, as well as of greater cold. Some have said, 

 of greater precipitation, and not of greater cold ; but the former 

 of these two statements has general acceptance. If the surface 

 waters of the Atlantic basin were warmer than now owing to a 

 rise of land along a belt from southeast to northwest through 



VOL. XLIV. 60 



