468 TRANSACTIONS OF THE AMERICAN INSTITUTE. 



of mountains had been pushed up in one grand chain, it would 

 have been from three to five miles in height ; but fortunately it 

 was thrown up in three or four great folds with breaks in them. 

 Between New York city and Albany, the Harlem R. R. cars cross 

 the region included in the Appalachian system, and yet we do not 

 pass through a mountain or over a mountain, but wind through 

 the breaks. At the same time with the Appalachian mountains, 

 the Colorado mountains in Texas running into Arkansas, were 

 thrown up ; and the peninsular of Yucatan has a system of moun- 

 tains belonging to the same age. 



The next system of mountains is the Rocky mountains. Formerly 

 we were taught to believe that the Rocky mountains were the back- 

 bone of the American Continent ; but they were not in existence 

 as a high range unitl the continent to the north and east was dry 

 land and well stocked with animal life. The Appalachian mountains 

 were thrown up after the close of the carboniferous era; and the 

 Rocky mountains, running in the opposite direction, were thrown 

 up long after the Cretaceous age. West of the Rocky mountains 

 is the Sierra Nevada, of a later age than them ; and west of it 

 another range including the Cascade mountains, still later in its 

 origin. Between the Sierra Nevada and the Rocky mountains, 

 are various systems, short, isolated, and the latest of all. These 

 are generally of volcanic origin. 



After the North American Continent had a«!sumed nearly its 

 present form, there was a submergence of the entire northeastern 

 portion of it, burying the tops of the Catskill mountains a thou- 

 sand feet beneath tlie bosom of the ocean. Wherever you go 

 upon the rocks of this region, you find them worn smooth and 

 grooved as if by the passage of something over them Avearing 

 these grooves in a certain direction. You also find immense 

 boulders, evidently moved from their original positions, tumbled 

 about promiscuously. It was the great deluge of the northern 

 waters, carrying floating ice, anchor ice, and all the other phe- 

 nomena of an Arctic climate, that blotted out all the past, 

 destroyed the mastadon. the rhinoceros, the hippopotamus, and 

 prepared the continent for a new creation of animals and plants 

 better adapted to the use of man. Mount Washington, some of 

 the highest peaks of the Green mountains, and the higher peaks 

 of the Alleghany mountains, were lone islands in this vast Arctic 

 ocean. The average thickness of the drift deposited at this time 

 is about 100 feet; and you can imagine the mighty power which 



