208 Canadian Record of Science. 



gathered in the opposite hemisphere. He might observe 

 that the great oceanic area of the Pacific and Antarctic 

 Oceans is dotted with islands — like a shallow pool with 

 stones rising above its surface — as if its general depth were 

 small in comparison with its area. He might also notice 

 that a mass or belt of land surrounds each pole, and that the 

 northern ring sends off to the southward three vast tongues 

 of land and of mountain chains, terminating respectively 

 in South America, South Africa, and Australia, towards 

 which feebler and insular processes are given off by the 

 Antarctic continental mass. This, as some geographers have 

 observed, 1 gives a rudely three-ribbed aspect to the earth, 

 though two of the ribs are crowded together and form the 

 Europ-asian mass or double continent, while the third is 

 isolated in the single continent of America. He might also 

 observe that the northern girdle is cut across, so that the 

 Atlantic opens by a wide space into the Arctic Sea, while 

 the Pacific is contracted toward the north, but confluent 

 with the Antarctic Ocean. The Atlantic is also relatively 

 deeper and less cumbered with islands than the Pacific, which 

 has the higher ridges near its shores, constituting what some 

 visitors to the Pacific coast of America have not inaptly 

 called the ' back of the world,' while the wider slopes face 

 the narrower ocean, into which, for this reason, the greater 

 part of the drainage of the land is poured. 2 The Pacific 

 and Atlantic, though both depressions or flattenings of the 

 earth, are, as we shall find, different in age, character, and 

 conditions; and the Atlantic, though the smaller, is the 

 older, and, from the geological point of view, in some res- 

 pects, the more important of the two. 



If our imaginary observer had the means of knowing 

 anything of the rock formations of the continents, he would 

 notice that those bounding the North Atlantic are, in general, 

 of great age — some belonging to the Laurentian system. 



1 Dana, Manual of Geology, introductory part. Green, Vestiges of 

 a Molten Globe, has summed up these facts. 



2 Mr. Mellard Eeade, in two Presidential addresses before the 

 Geological Society of Liverpool, has illustrated this point and its 

 geological consequences. 



