286 Geological Society. 



high western moors of Yorkshire and of the enormous breaks accom- 

 panying its escarpment from the heart of Craven to the foot of Stain- 

 moor. The range and effects of one part of the great Craven fault 

 have been described, with excellent illustrative sections, by Mr. Phillips 

 of York. Taking the subject up where he had left it, I have traced 

 a connected system of breaks to the foot of Stainmoor, and shown 

 that by a prolongation of the great Craven fault, producing an 

 enormous downcast on its western side, the entire carboniferous 

 zone of the Lake Mountains has been nearly cut off from the central 

 chain with which it must undoubtedly have been once continuous. 



Another enormous break, passing under the escarpment of the 

 Cross Fell range, meets the prolonged line of the Craven fault near 

 the foot of Stainmoor. The forces producing this double system of 

 disruptions appear to have been contemporaneous, and by their joint 

 action have thrown whole mountain masses of the carboniferous series 

 headlong into the valley of the Eden. 



We have direct proof that all the fractures above mentioned took 

 place immediately before the formation of the conglomerates of the 

 new red sandstone; and we have the strongest reasons for believing, 

 that they were produced by an action both violent and of short dura- 

 tion : for we pass at once from the inclined and disrupted masses to 

 the horizontal conglomerates now resting upon them ; and there is 

 no trace of any effect that indicates a slow progress from one system 

 of things to the other. 



Lastly, we have the clearest evidence to show that these vast dis- 

 ruptions were produced during the elevation of the carboniferous 

 chain ; and, if I am not mistaken, during the same period arose many 

 minor cracks and fissures, forming the moulds into which were, in after 

 times, cast some of the richest lead veins of our island. 



It is well known that the rich carboniferous deposits of this coun- 

 try undergo a great change of structure in their range from the Bristol 

 Channel to the valley of the Tweed j and I hope I shall not be thought 

 to wander too far from my object, if I attempt shortly to explain in 

 what the changes consist, and what are their modifications. 



All our coal formations are essentially composed of mountain 

 limestone, sandstone, and shale : they differ only in the mode in 

 which these constituents are aggregated In the various coal-basins 

 on the Bristol Channel, the limestone-beds are developed only in 

 the lower, and the coal-bearing-beds in the upper part of the series ; 

 and the two members are separated by nearly unproductive deposits 

 of millstone-grit and shale. 



Almost in the same words we may describe the carboniferous series 

 of Derbyshire. There, however, the millstone-grit is more complex, 

 and of very great thickness ; and subordinate to the great shale are, 

 here and there, very thick masses of a peculiar, thin-bedded and some- 

 what argillaceous limestone. 



On the re-appearance of the carboniferous limestone, at the base 

 of the Yorkshire chain, we still find the same general analogies of 

 structure : enormous masses of limestone form the lowest part, and 

 the rich coal fields the highest part of the whole series j and, as in 



the 



