440 SKETCH TOWARDS A 



initting fresh successions of vegetation at the same 

 low levels : while, if I may again resort to the argu- 

 ment from final causes, the importance of the ultimate 

 ohject will justify such a proceeding, and in the case 

 of the lignites as in this one, under what we must be- 

 lieve of the Designs of the Deity in the creation and 

 arrangement of the Earth. 



If I can but repeat my entire ignorance of the con- 

 dition of the earth after the depression of the coal 

 strata, it is here at least that the vegetable deposits 

 were mineralized; while I have shown reasons for be- 

 lieving that this change was not induced by heat. But 

 the great blank in a Theory of the Earth which here 

 remains to be filled, respects those strata which must 

 have been forming at the same time as those intended 

 for coal were growing, in the preceding state of the 

 earth, and which we cannot now distinguish from 

 those which have been subsequently deposited : while 

 there are the same precise difficulties also, respecting 

 those periods in which the two great lignites are 

 forming. 



Respecting the strata which follow the coal series, a 

 little will suffice, after the remarks in a former chapter 

 on the subject, and the preceding ones on the condi- 

 tions which include the lignites. If the inferior lime- 

 stone, not alternating with earthy strata, and containing 

 coral, appears to have been formed by coral banks, 

 those that contain shells, and include earthy strata, have 

 been produced jointly by the growth of animals and 

 the degradation of land. If I assigned two possible 

 causes for the magnesian limestone, I even now hesi- 

 tate whether, being a probable produce from the moun- 

 tain lime, by degradation, it might not also have under- 

 gone the action of heat ; so much is there, in the cha- 

 racters of the red marl, to lead to a suspicion of this 



