THE SECONDARY STRATA. 261 



cable to all the strata wherever similar circumstances 

 occur. 



Still, it is the presence of salt which offers the great 

 difficulty ; and till the cause of this is explained, the 

 history of this deposit must remain one of the greatest 

 hlanks in the science of geology ; that blank, which, 

 with the philosophy of mineral veins, still utterly 

 unintelligible, and that of the green sand, hitherto un- 

 suspected to be another proof of our ignorance, forms 

 at present the chief very decided deficiency in a Theory 

 of the Earth. If the confession of my own is but 

 that of the general ignorance, this open acknowledg- 

 ment may perhaps give some force to my opinion, 

 when I say, that in all else, the Theory of the Earth, 

 as it may here be deduced and will hereafter be 

 sketched, wants little to render it as perfect as can now 

 easily be expected, and wants nothing which relates 

 to its essential points. 



I do not think it now necessary, in this sketch of 

 the theory of the secondary strata above the coal, to 

 distinguish the muschelkalk and the quadersandstein ; 

 since the same general reasonings will apply, though 

 I limit this view to the received English series. All 

 that can be requisite is, to consider these as analogical 

 deposits produced in other places, under the same 

 general circumstances; and thus the same theoretical 

 views will equally suffice for all otber analogous de- 

 posits, in whatever part of the world they may here- 

 after be studied. In applying it therefore to the Lias 

 of England, the obvious inference is, that after the 

 deposition of the red marl, an increase of the organic 

 creation became the source of the calcareous beds in 

 this series ; while being as yet but few, in comparison 

 to what their power of propagation was hereafter to 

 render them, the argillaceous and arenaceous deposits 

 from the supramarine land bore a larger proportion to 



