290 CLIMATIC CONDITIONS OF THE GLACIAL EPOCH. 



England and along the Great Lakes, and we have at once a sufficient cause 

 for all the phenomena of the northern drift and of the surfoce geology of 

 the region extending from below the line of Pennsylvania northward to 

 beyond the limits of the Continent, and west to the base of the Rocky 

 Mountains. It is true that the Polar regions are difficult of access, and that 

 much remains to be found out in regard to the meteorological and climatic 

 conditions which prevail there ; but enough is known, especiall}' of the lands 

 within the Arctic. Circle, to materially assist us in the present investigation. 

 It will be found — as the writer believes — on examining the records of the 

 investigations of the most trustworthy explorers of the Polar regions, that 

 the essential points which we have endeavored to bring out in describing 

 the present glaciation of the Alps, the Scandinavian Pange, and the Hima- 

 laya are repeated on the great land masses north of tlie Arctic Circle ; and 

 that such differences as do present themselves are in harmony with the 

 changed conditions offered by the necessarily jieculiar jiosition of those 

 exceptionally situated portions of the earth. But it will not appear from 

 the study of the glacial phenomena of the lands within the Arctic Circle 

 that the facts authorize us to believe that a low temperature is necessarily 

 accompanied by a large amount of snow, and the conversion of that snow 

 into ice ; nor shall we find that we may assume — basing our assumption on 

 that which can be seen in the higher latitudes — that a general ice-sheet can 

 form on level land and move in all directions from its centre, or towards a 

 more southern latitude. In short, all the difficulties presented by the glacial 

 and drift phenomena of northeastern North America are not removed bj' a 

 study of the Polar areas. 



As pi'eparatory to an examination of the glacial characters of the North 

 Polar regions it will be well to call the reader's attention to the peculiar 

 distribution of land and water in the hitjher latitudes of the northern hemi- 

 sphere, a matter which is of the greatest possible importance in connection 

 with the subject before us. 



The Arctic Circle lies almost throughout its whole extent on the Innd, 

 and at the same time it npproximately marks the northein limit of the con- 

 tinental land masses. A considerable part of the parallel of 70° does, how- 

 ever, intersect land, because a very small part of Europe and a much laiger 

 one of Siberia lie north of that line. Leavino; out of consideration the 

 somewhat extensive area between the mouths of the Yenisei and the Lena, 

 which belongs to the continent of Asia, it may be said with truth that, so far 



