THEORY OF THE EARTH. 439 



their places, in the mind of any reader. I must first 

 examine what belongs to the theory of each distinct 

 condition of the earth. 



Of the sixth, being also the first affording any re- 

 mark, I have said all that I know, in suggesting that 

 its strata, consisting of our primary, must have origi- 

 nally resembled the present secondary ones ; and I will 

 not dwell on what any geologist can supply, or con- 

 jecture as well as myself, respecting this condition of 

 the earth. But the conglomerate of the old red sand- 

 stone proves that tumultuary state of the waters, at 

 the previous revolution, whence I have endeavoured, 

 by analogy, to deduce the causes of certain modern 

 alluvia : while the sufficient absence of organic bodies 

 is the argument for an extinction of life at this period. 

 If the mountain limestone marks the gradual increase 

 of life, and, as I formerly suggested, the production of 

 coral banks, so do some of its remains prove that it 

 was, in some places, formed in shallow aestuaries, in- 

 dicating therefore rivers. But it is superfluous to 

 say that some of them also denote a terrestrial vege- 

 tation, since it is on the dry land of this Earth that the 

 preparations for coal are in progress. 



If the theory of coal is therefore included in this 

 subsidiary portion of the general theory, I need but 

 repeat, most briefly, what I have formerly explained at 

 great length, and under ample evidence. Be the plants 

 what they may, they were the inhabitants of moist 

 lands ; of the marshy margins of aestuaries, and pro- 

 bably also of inland lakes. Their remains were depo- 

 sited as peat is now ; and where coal beds alternate 

 with rocky strata, it is because such beds of peat were 

 occasionally inundated by earthy matters. But I can 

 see no method of explaining the great depth of these 

 deposits^ except by slow subsidences of the land, per- 



