GEOLOGICAL NOTES 

 ON THE DISTRICT NORTH OF MALHAM. 



COSMO JOHNS, M.I.Mech.K., F.G.S. 



In a few pages it is impossible to discuss, with any approach to 

 adequacy, the complex structural features of the great zone of 

 fracture and displacement that runs almost due east from 

 Clapham past Malham to the valley of the Wharfe near Grass- 

 ington. Its description as being characterised by two step 

 faults with the downthrow towards the south and with a total 

 vertical displacement of many hundreds of feet will sufficiently 

 prepare the visitor for an example of normal faulting on a 

 gigantic scale, and any attempt at an elaborate discussion of 

 the physical history of the area would be out of place. It 

 will suffice to say that many of the differences that exist among 

 those who have attempted to explain the structure of the 

 faults that divide the Craven Lowlands from the Uplands are 

 due to the failure to recognise more than one system of faulting. 

 Fortunately, for the purpose of this present paper, we are 

 chiefly concerned with the east and west system to which the 

 Inner and Outer Faults of the Malham area belong, and thus 

 it will not be necessary to refer except very briefly to the N.W. 

 and S E. system of faults, which are characteristic of the Ingle- 

 ton district. Mention, however, must be made of the E. and W. 

 system of anticlines, for it is this anticlinal system that forms 

 the boundary between the Upland and Lowland type of the 

 Lower Carboniferous rocks. The E. and W. Faults are closely 

 related to the anticlinal system referred to, and in the district 

 under discussion we might define the structure as a faulted 

 anticline. Any such definition must, however, be tentative, 

 for differential movements were in progress during late Visean 

 time, and continued until the Ingleborough grit was laid down. 

 So far we have simply discussed the area of which the 

 Outer Craven Fault is the southern boundary. As originally 

 mapped, with its marked outward bend near Scalebar, this 

 fault involved a reading of the structure which gave the mass 

 of limestone between the two faults a thickness very much 

 greater than that found north of the Inner Fault. Evidence 

 has now been brought forward* which renders the old view 



* Proc. Yorks. Geol. Socy., 1908, p. 393. 

 igio June i. 



