PHYSICAL HISTORY OF THE AMAZONS. 



439 



that it connected the shoals of Newfoundland with the 

 continent ; that Nantucket, Martha's Vineyard, and Long 

 Island made part of the main-land ; that, in like manner 

 Nova Scotia, including Sable Island, was united to the 

 southern shore of New Brunswick and Maine, and that 

 the same sheet of drift extended thence to Cape Cod, 

 and stretched southward as far as Cape Hatteras ; — in 

 short, that the line of shallow soundings along the whole 

 coast of the United States marks the former extent of 

 glacial drift. The ocean has gradually eaten its way into 

 this deposit, and given its present outlines to the conti- 

 nent. These denudations of the sea no doubt began as 

 soon as the breaking up of the ice exposed the drift to 

 its invasion ; in other words, at a time when colossal 

 glaciers still poured forth their load of ice into the At- 

 lantic, and fleets of icebergs, far larger and more numer- 

 ous than those now floated off from the Arctic seas, 

 were launched from the northeastern shore of the United 

 States. Many such masses must have stranded along the 

 shore, and have left various signs of their presence. In 

 fact, the glacial phenomena of the United States and 

 elsewhere are due to two distinct periods : the first of 

 these was the glacial epoch proper, when the ice was a 

 solid sheet ; while to the second belongs the breaking up 

 of this epoch, with the gradual disintegration and disper- 

 sion of the ice. We talk of the theory of glaciers and 

 the theory of icebergs in reference to these phenomena, 

 as if they were exclusively due to one or the other, and 

 whoever accepted the former must reject the latter, and 

 vice versa. When geologists have combined these now 

 discordant elements, and consider these two periods as 

 consecutive, — part of the phenomena being due to the 



