TIME NECESSARY. 



283 



at the Falls. Many have been the successive revolutions 

 in organic life, and many the vicissitudes in the physical 

 geography of the globe, and often has sea been converted 

 into land since that rock was forced. The Alps, the 

 Pyrenees, the Himalaya, have not only begun to exist as 

 lofty mountain chains, but the solid materials of which 

 they a'*e composed have been slowly elaborated beneath 

 the sea within the stupendous interval of ages here allu- 

 ded to."* 



If time, to anything like the amount here insisted on, 

 have really elapsed between the commencement of life 

 and its attaining its highest forms, we must see that the 

 space comprised by the life of an individual, or even that 

 longer portion during which mankind have been watch- 

 ing the wonders of nature, is not sufficient to allow more 

 than a chance of any transition of species being or having 

 been observed, except perhaps in the humble fields where, 

 as was formerly remarked, reproduction is most active 

 and type3 least defined. If, however, even in our limited 

 command of this grand element, we can detect such 

 transitions as those amongst the cerealia, or in a com- 

 mon infusion, may we not well suppose that much greater 

 have taken place in the course of the vast series of ages 

 here described ? Absolute proof on such a point may be 

 impossible; but nearly the same effect may be reached, if 

 we see vestiges of the supposed facts in living phenom- 

 ena, just as we conclude upon the formation of stratified 

 and igneous rocks from seeing similar phenomena, gen 

 erally on a smaller scale, taking place before our eyes. 



There is another mode of attaining the means of a 

 tolerably definite conclusion, where perfect par oof is un- 

 attainable. This is to show a portion or fraction of the 

 entire phenomenon, in conformity with the hypothesis as 

 to the whole. Now this can be done in the case under 

 consideration. There are isolated parts of the earth, 

 which we know to have become dry land more recently 

 than others. Such is the Galapagos group of islands, 

 situated in the Pacific, between five and six hundred miles 

 from the American coast. They are wholly of volcanic 

 origin, and are considered by Mr. Darwin as having been 

 raised out of the sea " within a late geological period .'• 

 Here, then, is a piece of the world undoubtedly younger, 

 so to speak, than most other portions are in their totality, 

 * Travels in North America, i., 52 



