OF THE EARTH. 501 



fercnt intervals ; and those intervals, when conspi- 

 cuous or extensive in their effects, causing the revo- 

 lutions of condition here described. 



If there are differences in any respect between the 

 natures of these several rocks or the collateral ap- 

 pearances attending them, the causes have been for- 

 merly explained, nor do they affect this reasoning. 

 But I may here refer to the Moon in illustration of 

 this condition of the globe of our Earth ; while all 

 analogy makes us infer that every planetary body is 

 of the same essential nature. It is a congeries of 

 mountains, of which the far larger portion is visibly 

 volcanic, as all may have been ; while we trace, with 

 perfect security, successions of volcanic mountains, or 

 of eruptions, in which every part of its surface has 

 been engaged at different times, as its volcanoes still 

 occasionally burn. And there we also perceive the 

 probable reasons why our own surface differs from 

 that of this planet ; especially, why the Earth has lost 

 so widely those decided proofs of former volcanoes 

 which that has preserved in the integrity of its innu- 

 merable Craters. It contains no water, and possesses 

 a very slender and limited atmosphere : whence it has 

 not been subjected to the same causes of waste which 

 are ever acting on the surface of the Earth. But 

 thence also, its volcanic or un stratified rocks have 

 never been obscured by the strata which have covered 

 those on our own surface ; whatever revolutions ana- 

 logous to those of the Earth it may have undergone. 

 The volcanic actions in the earth have often elevated 

 the strata without allowing the fused rocks to break 

 through them, as happens daily at present ; and the 

 more delicate volcanic records have also disappeared 

 in the successions of waste and of revolutions, as must 

 be especially plain of all the earlier ones. 



The perfect simplicity and consistency of this view, 



