American Assocuvtion. 28'S 



enormous lapse of time that lay between ^ and it was argued that 

 between other strata similar lapses of time may feave intervened, 

 possibly marked by the occurrence of great rivers, the deposits of 

 which have not beeil preserved. The most perfect se<juence of 

 formations, even over large areas, was oiily a collection of frag- 

 ments. Mr. Ramsay then referred at some length to tke Glacial 

 Epoch. It was generally believed that the whole of the British 

 territory, if we except perhaps some of the mountains in the north 

 part, had been submerged during the Glacial Epoch. We find 

 marine shells of an Arctic type at 1,300 feet above the level of the 

 sea. This of itself would not be a demonstrative proof that our 

 ■country had a cold climate .during that time ; but proof is quite 

 perfect of glaciers having existed at that period. He had recorded 

 it as his opinion that the chief causes of the extinction of species, 

 and of the changes of the species, in the different formations, were 

 to be found in the great changes in the physical geography, such 

 as large tracts of land being fot a length of time out of water^ 

 and being again submerged; and also from climatal changes, 

 "which might be due to changes in physical geography." 



FORMATION OF CONTINENTS. 



A very remarkable paper was read by Prof. Pierce, on the 

 origin of the great lines of land and water on the surface of our 

 globe. The author went back to the supposed fluid condition of 

 our planet, and attempted to show that the diurnal solar action 

 on a cooling sphere would establish a tendency to the produc- 

 tion of lines of cleavage along great circles tangental to the arctic 

 circle^ these directions being actually those of the principal lines 

 of our existing continents. This view, though probably not 

 current with most of the geologists present, points to at least a 

 curious coincidence, which in its connection with the directi'.'U 

 of the earliest dry land and our modern coast lines, merits atten- 

 tion. 



" Professor Pierce remarked that the principal lines of the con- 

 tinents were great circles, tangent to the polar circle. This was 

 especially the case with the coasts of tho Pacific ocean. He 

 illustrated this on the terrestrial globe. He then pointed out the 

 same fact as regarded the eastern coast of Africa, the eastern coast 

 of Hindostan, the eastern coast of Asia, the eastern coast of 

 North America, the western coast of Hindostan, the line of the 

 eastern Archipelago, the western coast of America, and (perliaps) 

 the western coast of Africa. Any one might perceive liiex-e 



