FeatherstonhaugK^ s Geological Report. 113 



their excellence for particular purposes depends, maybe caused 

 by the inherent qualities of the plants of which they are the 

 supposed residuum. There is one particular in which the 

 bituminous coal region of this country differs widely from that 

 of England : here the beds lie generally as undisturbed as 

 when they were deposited ; there they have been dislocated 

 and shifted in a surprising manner. There are instances of 

 faults., in the Newcastle district, where the strata have been 

 rent, and a subsidence of one portion has taken place to the 

 extent of 140 fathoms, near 850 feet. When this was effected, 

 of course the corresponding part would have formed an 

 escarpment to that extent ; yet all this has been removed, 

 for the surface of the country is now level. 



Not having, upon this occasion, passed through the great 

 deposites of anthracite coal, 1 shall not refer to them any 

 further than to observe that they are totally distinct, as to 

 their geological position, from the bituminous coals, and of a 

 distinct quality. With some exceptions, as at Broad-top 

 mountain, in Bedford county, Pennsylvania, they are entirely 

 non-bituminous, and are all, without exception, deposited low 

 down, amongst what have been called the grauwacke rocks, 

 and in that group which, when it comes to be minutely ex- 

 amined and compared, will, I have no doubt, prove the equiva- 

 lent of Mr. Murchison's Silurian rocks. There are very 

 strong resemblances amongst some of the fossil plants found 

 in the shales of both the bituminous and non-bituminous beds, 

 but I believe the amount of the differences, when they are 

 carefully compared by experienced observers, which measures 

 are taking to have done, will prove to be great and charac- 

 teristic. 



Deposites of hydrate of iron accompany the bituminous coal 

 measures, as they do in England, but in this country they vary 

 exceedingly in their extent and capacity. The beds in the 

 neighborhood of the Potomac appear to be thick, and, if they 

 are continuous, will be of immense value. The deposites in the 

 8 



