306 COAL. 



penetrated, the coal series be present, or, if even pre- 

 sent, whether it contains beds of useful coal. Yet we 

 cannot decide on its absence ; and henoe, wherever the 

 red marl is found, it is always possible that coal may 

 lie beneath it: and, that it will thus be discovered 

 hereafter, much more extensively than it has yet been, 

 is far from improbable. Thus it may exist even be- 

 neath the sands of Asia and Africa. And hence we 

 derive the necessity of extreme caution in distinguish- 

 ing, between the older and the later sandstones. 



The rules for discovering coal follow necessarily 

 from this view of its connexions. It is superfluous, 

 therefore, to record the technicalities of miners on this 

 subject ; as they are thus reduced to a simple prin- 

 ciple. The same views will operate as a caution 

 against the frauds too often practised by the interested ; 

 and thus, further, demonstrate the value of geological 

 knowledge as a branch of general education, if any 

 thing could convince the higher Public, of the utility 

 of knowledge, in statistics, ceconomy, and science. 



It will now be proper to enumerate a few examples 

 of the variations which occur in this series, as it is 

 best known to us. The coal of Gloucestershire suc- 

 ceeds to a sandstone which follows the mountain lime- 

 stone and red sandstone ; and, after some alternations 

 with the usual strata, it is followed by a coarse grit of 

 great dimensions, and by a similar coal series, suc- 

 ceeded by shale and coarse grit. Over this are placed, 

 in reverse order, the red marl, the lias, and the lower 

 beds of the oolithe limestone. Near Bristol, the 

 depth of the entire deposit is said to be four thousand 

 four hundred and forty feet, containing thirty-one coal 

 beds : and in Derbyshire there are enumerated thirty 

 beds, varying from six inches to eleven feet; the total 

 thickness of coal being twenty-six yards. In this series, 

 between the magnesian and the mountain limestone, 



