194 ON THK ORIGIN OF COAL. 



rather than paroxysmal disturbances, similar to 

 those which dislocated the carboniferous series, 

 at intervals, long after its formation. 



Whatever the cause of the numerous subsi- 

 dences that have evidently taken place in the 

 crust of the globe, it must certainly have been 

 deep seated, and acted at intervals over vast 

 periods of time, commencing long before the 

 formation of the Protozoic rocks, extending over 

 the whole of the Palaeozoic rocks, and up to the 

 latest Tertiary deposits. 



We are at present in want of a correct vertical 

 section of the earth's crust, showing the materials 

 composing its various beds, and the nature of 

 their organic remains. When this is supplied, we 

 shall be enabled to trace back the physical history 

 of our globe, and furnish the mathematician with 

 data from which to calculate, with absolute cer- 

 tainty, the changes which have taken place in the 

 solid particles of our planet, and to determine 

 whether some of the most important of them have 

 not been effected by the slow and silent process 

 of the radiation of heat, rather than by more 

 actively energetic causes. 



