GEOLOGY IN THE UNITED STATES 51 



taining no less than 196,660 square miles of coal bearing 

 territory. 



More important even than the determination of the 

 coal making processes, was the promulgation of the glacial 

 theory. In 1835 De Charpentier, a Swiss geologist, ad- 

 vanced the idea that the erratics and bowlder clays of his 

 country had been deposited by glaciers at some remote 

 period. This led all the geologists of Europe and America 

 to investigate a question that had been puzzUng scientists 

 for a long time. In America and Europe, over the northern 

 latitudes, stones, gravel, and sand, as well as masses of rocks 

 hundreds of tons in weight, are found as far as a hundred 

 miles and more south of the region where they were origi- 

 nally formed. That transported material was called drift, 

 and the stones and bowlders were formerly claimed as proofs 

 of the tumultuous action of an universal deluge. In 1840 

 Agassiz, of Neuchatel, in company with J. D. Forbes, noted 

 as an expert in the physics of glacier ice, and W. Buckland, 

 began a systematic study of the alpine glaciers. Their gigan- 

 tic task led to startling results. It seemed an im.possibility 

 for science to accept as a fact that nearly all of Europe and 

 North America had been enveloped in a great ice sheet many 

 miles in thickness, and in a comparatively recent period. 

 That ages of tropical splendor should have been succeeded 

 by such frightful desolation was beyond all conception, 

 but as the investigation proceeded the fact was proved be- 

 yond the shadow of a doubt. A study of the topography 

 of North America revealed the fact that an immense glacial 

 deposit had embraced the whole continent from Labrador 

 and Newfoundland to the western borders of Iowa, and even 

 farther west, and that it extended southward to the parallel 

 of 40 degrees. In Europe it extended down to 50 degrees, 

 where the temperature corresponds to that of the parallel 

 of 40 degrees in North America. The stupendous ice fields 

 did not remain stationary, but in time began to transport 

 themselves either in a southward, southeastward or south- 

 westward direction. The highest mountains were no obstacle 

 to their progress, and they moved over the great summits 

 of the White mountains and the Green mountains as if they 



