1847.] Association of Geologists and JVaturalists. 215 



Two great polar currents are constantly setting southwards — one 

 to the Southeast from Hudson's Bay, the other southwest from the 

 shores of Greenland — these two currents unite near the Gulf stream, 

 and result in one current. These currents bring along immense 

 masses and islands of ice. These islands bear along rocks, peb- 

 bles, &c., collected on them before their separation from the land 

 where they originally formed glaciers — they often ground and re- 

 main grounded for months, turned and moved in every possible 

 position by the wind and w aves. They would scratch the bottoms 

 of the valleys of the ocean, and would cause the excoriated appear- 

 ance which the rocks present. In Mr. Redfield's view, this agent, 

 of currents of water, was sufficient to account for many of the 

 geological phenomena which the earth presents. 



Mr. Desor could not conceive how the sides of the valley could 

 be scratched by this agent if the bottoms were. He exhibited 

 specimens of strata or scratched rocks from the glaciers of the 

 Grindelwold and Aar of Switzerland, from Essex County, this 

 state, from Norway, and from the terraces near Lake Ontario. 

 They are all similar in character — one cause must have produced 

 effects so similar. It would not do to say that one cause operated 

 in Norway, another in Switzerland, and still another on this con- 

 tinent. The effects were brought about by the slow^ action of a 

 mighty body. Glaciers have been observed not only in the Alps 

 but also in the polar regions. In Iceland glaciers exist for 50 

 miles in extent — such being the case, it requires no great effort to 

 believe in the existence of a glacier 3 or 400 miles in extent. It 

 is only necessary that the temperature should be lowered a few 

 degrees for them to exist. 



Commander Wilkes, U. S. N., late of the Exploring Expedi- 

 tion remarked that icebergs have a wide distribution, that they 

 were constantly changing their specific gravity, changing their 

 positions — what w^as a side at one time would become the bottom, 

 &c. — in this way the variety of striae might be accounted for. 



Professor Silliman with no view to object to the glacier theory, 

 for he desired to learn, asked its advocates to explain the exist- 

 ence of glaciers in regions where there were no mountains. The 

 theory as applied to the Alps and other mountainious districts was 

 good. 



Professor Adams, of Vermont, made a drawing of a rock of tal- 

 cose slate in the valley of Onion river, Vermont. It was round- 

 ed, beautifully polished and striseted on its surface. Near the 

 bottom on the rock was a depression or hollow, and upon the side 

 on which the power, whatever it was, first acted. This hollow 

 was not touched — it presents a rough and jagged outline. The 

 body appears to have struck the rock near its lower edge, and, 

 through the resistance made to its passage by the rock, to hav e 



