CONCLUSION. 757 



great seas ; and the incipient continents were at times spread with 

 fresh-water marshes, into which rills were flowing from the slopes 

 around. As the mountains enlarged, the rills changed to rivers, till 

 at last the rivers also were of majestic extent ; and the continents 

 were throughout covered with streams at work, channelling mountains, 

 spreading out plains, opening lines of communication, and distributing 

 fertility everywhere. 



Again, the first climates were all tropical. But, when mountains 

 and streams were attaining their growth, a diversity of climate (essen- 

 tial to the full strength of the latter) was gradually evolved, until 

 winter had settled about the poles as well as the earth's loftier sum- 

 mits, leaving only a limited zone — and that with many variations — 

 to perpetual summer. 



The organic history of the earth, from its primal simplicity to the 

 final diversity, has been shown to exemplify in many ways the same 

 great principle. 



Thus the earth's features and functions were successively individ- 

 ualized, — first the more fundamental qualities being evolved, and 

 finally those myriad details in which its special characteristics, its mag- 

 nificent perfection, and its great purpose of existence and fitness for 

 duty, largely consist. 



Conclusion. — The causes of the earth's movements which have 

 been considered appear to explain the evolution of the prominent 

 features of the globe ; and the special history made out for North 

 America may be safely regarded as an example of what will hereafter 

 be accomplished for all the continents. 



But Geology, while reaching so deeply into the origin of things, 

 leaves wholly unexplained the creation of matter, life, and spirit, and 

 that spiritual element which pervades the whole history like a proph- 

 ecy, becoming more and more clearly pronounced with the progressing 

 ages, and having its consummation and fulfillment in Man. It gives 

 no cause for the arrangement of the continents together in one hemi- 

 sphere (p. 10), and mainly in the same temperate zone, or their situa- 

 tion about the narrow Atlantic, with the barrier-mountains in the 

 remote west of America and in the remote east of Europe and Asia, 

 thus gathering the civilized world into one vast arena (p. 29) ; it does 

 not account for the oceans having, in extent and depth, that exact 

 relation to the land which, under all the changes, allowed of submer- 

 gence and emergence through small oscillations of the crust, and hence 

 permitted the spreading out of sandstones and shales by the waves 

 and currents, the building up of limestones through animal life, and 

 the accumulation of coal-beds through the growth of plants, — and 



