160 



ON THE ORIGIN OF COAL. 



the thickness of its various beds, commencing 

 with the lowest millstone grit and terminating (as 

 far as yet ascertained) by the red clays of Ardwick 

 near Manchester. It is full six thousand six 

 hundred feet in thickness, and contains at least 

 one hundred and twenty different seams of Coal. 

 In a former paper, read before the British Asso- 

 ciation at Manchester,* it was divided into lower, 

 middle, and higher. This division will be adhered 

 to in the present instance, merely giving the 

 workable seams. 



Now all these seams, whether workable or not, 

 have floors, as beds on which the Coals rest are 

 termed. These consist of fine silt, called by the 

 miners warrant (sometimes warren) earth, fire 



* Transactions of British Association, Vol. xii. p. 46 ; and 

 Sturgeon's Annals of Philosophical Discovery and Monthly 

 Reporter of the Progress of Practical Science, Vol. i. 



