68 Mary : The Rigidity of North-west Yorkshire. 



unless a concealed fold or fracture brings up older rocks just 

 south of the Craven Fault system. Again, as in Edenside, a 

 mass of Lower Carboniferous Limestone is bent down away 

 from the rigid block between the north and south Craven 

 faults. Lastly, as before, we have Permian rocks brought 

 down by the outer fault at Westhouse, the only difference 

 being that the area occupied by these rocks south of the 

 Craven fault is much smaller than that covered by rocks of the 

 same age in the Eden Valley. Apart from this the similarity 

 of conditions in the new areas is remarkably illustrated by 

 Prof. Kendall's researches, for he has proved that the move- 

 ment along the Craven fault system, like that along the Pennine 

 Fault, was in progress during Permian times. 



The earth-waves south of the Craven fault differ in a 

 considerable degree from those west of the Pennine fault. The 

 latter may be compared with the great rollers of the ocean, the 

 former with those of a choppy sea, ridges and troughs alternat- 

 ing rapidly, of varying degrees of magnitude. Are the smallest 

 of these of the nature of eddies swirling on the larger waves ? 

 The answer to that may be left to Yorkshire geologists, who 

 will, I feel sure, settle the vexed question as to the origin of 

 the reef-knolls whose structure was originally ascertained by 

 Tiddeman. 



The recognisable waves are here breaking obliquely to the 

 southern margin of the block, the directions of these rocks 

 being on the whole north-east and south-west. 



The conditions west of the Dent Fault are more complex, 

 but a few words must be devoted to them. 



The Coniston Limestone crops out parallel to the fault 

 from Cautley, north-east of Sedbergh, to Dent, where it disap- 

 pears under the Carboniferous rocks to the east of the fault, 

 but probably runs approximately parallel to it, until the 

 strike swings round where the Dent Fault joins the Craven 

 Faults, north-west of Ingleton. The older rocks he to the 

 east of the Coniston Limestone, forming part of the rigid block. 

 To the west we have a remarkable set of structures forming a 

 complex trough, with an axis running approximately north 

 and south. The Coniston Limestone occurs on each side of 

 this trough. Its eastern outcrop has already been noticed. 

 Its western one occurs far away near Dalton-in-Furness, where 

 the strata strike again north and south. Between these two 

 outcrops, the slate rocks, newer than the Coniston Limestone, 

 appear ; the newest, the Kirkby Moor Flags, in a tract starting 

 at Kendal, and extending southward. The axis of the centre 

 of this trough is roughly north and south, so that the general 

 E.N.E.-W.S.W. strike of the slate rocks of the Lake District 

 is here modified by a subsidiary north and south strike between 

 the rigid block in the east, and a possible similar block to the 



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