THE FAUNA OF BRITAIN. 1 29 



in the sole of a glacier or pushed up in front of it 

 The older view, however, which agrees so much better 

 with the facts of distribution, fortunately has not 

 disappeared among geologists. "When we call up," 

 says Mr. Mellard Reade (3, p. 435), "before our 

 mental vision the simple and well-known facts of 

 nature which suffice to explain the marine drifts on 

 the theory of submergence, it seems unnecessary 

 to resort to the ingenious and artificial system of 

 physics elaborated to explain the phenomena of 

 land-ice." 



" When we have more knowledge of the glaciers 

 of the Arctic Regions, and facts, in place of 

 ingenious suppositions, to base our reasoning upon, 

 we may possibly have to revise all our glacial con- 

 ceptions. In the meantime, the submergence theory 

 of the origin of high-level shelly gravels and sands 

 seems to me by far the simpler of the two theories, 

 and the most consistent with the facts and phenomena 

 which the labours of a succession of enthusiastic geo- 

 logists have made us acquainted with." 



Among those geologists, and they form the majority, 

 who hold that Ireland was covered by land-ice, there is 

 a great diversity of opinion as to its extent. Messrs. 

 Close, Kinahan, J. Geikie, and others believe that 

 the ice covered practically everything, whilst others 

 who claim to have examined the ground with equal 

 care, such as Professor Carvill Lewis, were led to 

 believe that the south of Ireland, with the exception 

 of a few local glaciers, was free from ice. The glacial 



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