244 GLIMPSES OF NATURE. 



Devonian series, to spend money in boring for Coal 

 through the Devonian would be as futile a proceeding 

 as that of trying to lift water with a sieve. 



Suppose, however, that the surface rocks of the 

 estate were of Permian age, and that these latter rocks 

 were not inconveniently thick, then the prospect of 

 finding coal measures would amount well-nigh to a 

 certainty. It is this succession of the rocks which 

 forms the basis of all geological calculations about the 

 finding of minerals and concerning the nature of the 

 rocks which occur in any locality. It is this very 

 thought which has to be taken into account in dis- 

 cussing the occurrence of coal at Dover. 



If we inquire into the order of the rocks which crop 

 up to the surface at the coast, we find them, of course, 

 to belong to the Chalk series. Now, the Chalk is a 

 long way younger than the Coal. It belongs to quite 

 a distinct period of the earth's history from that which 

 witnessed the growth and luxuriance of the Coal 

 vegetation. Tracing the succession of the rocks from 

 the Coal to the Chalk, we find the Permian lying, as 

 we have seen, above the Coal. Then we pass upwards 

 in point of position, and onwards in point of time, to 

 the Trias formations. 



After and above the Trias come the Oolite rocks, 

 and, finally, above the Oolite lie the Chalk rocks them- 

 selves. These formations are divided each into a 

 whole series of subordinate strata marked by local and 

 other peculiarities ; but the main point for us to keep 

 in view is the plain fact that if the Coal rocks are 

 separated from the Chalk by the Permian, Trias, and 

 Oolite formations, which attain many thousands of feet 

 in thickness, it would seem a practically hopeless idea 

 to expect to be able to reach the Coal by any amount 



