258 THE EVOLUTION OF CONTINENTS. 
The trend of the island system of the southwestern 
Pacific is very suggestive. The diagram copied from 
Danas Manual of Geology, with the addition of Aus- _ 
tralia and a part of Asiain place, shows this very clearly. 
To these problems a third must be added : 
The rectangularity of the coast of the Pacific, the op- 
posite of the parallelism of the Atlantic. The trend of 
the eastern side of Asia instead of being parallel to the 
western side of America, is almost perpendicular to it. 
In regard to the literature of the subject, I have been 
able to find very little. The belief of scientists in a 
general way, appears to be, that as our earth cooled, a 
crust was formed all over it, with tolerable uniformity ; 
that as the interior cooled and shrank, the immense 
weight of the crust produced corrugations on its surface, 
and that these were, from some cause, not generally 
distributed, but were in huge patches, the largest of 
these being what we now call the eastern and western 
continents. This would account for a portion of the 
earth’s crust being higher than the rest, but not for the 
direction of the trends. 
Prof. Dana, in his Manual of Geology, (third edition, 
page 816), offers the following : 
The continents were the parts of the earth’s crust that 
first stiffened in the gradual cooling of the exterior. 
These parts sank as they solidified, and of course there 
was an overflow from either side, which also cooled. 
And this process went-on until the mass became too 
viscid for it to continue. Finally a layer of crust-rock,” 
miles in thickness, was made over the great continental 
areas. Throughout the other portions of the sphere, 
the surface, whether liquid or beginning to solidify, 
had one level. The earth then was one vast plain, the 
present continental portions solid, the oceans liquid. 
These liquid portions, as they cooled, would shrink more 
than the solid parts ; hence, as they hardened into rock 
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