GEOLOGY. 23 



contrary been marked by a general eruption of disturbing 

 forces, of the energy of which we may form some kind of an 

 idea by studying the traces which they have left behind them 

 in the tract of country with which we are here more par- 

 ticularly concerned. At Cullercoats the Tynedale fault dis- 

 locates a mass of Magnesian Limestone strata, but although 

 such is the case we may confidently infer from the fact of 

 the nonconformity of the plane of the stratification of the 

 great mass of the Magnesian Limestone deposits in Durham 

 and throughout Yorkshire to that of the subjacent Millstone 

 Grit and Coal Measures, that it is to the earlier part of the 

 Permian epoch that we must look as the period of the Craven 

 and great Pennine dislocations, especially as the condition of 

 the beds in the valley of the Eden altogether confirms this view 

 of the case. So that we have the upheaval of the whole mass 

 of our western moorlands in the manner which has already been 

 described and the entire sweeping away of whatever portion of 

 the beds of the Coal Measure series may have been deposited 

 on the east of them to appeal to as a criterion of the extra- 

 ordinary power and activity of the forces which came into opera- 

 ation at the era at which we have now arrived. 



It is this upheaval and denudation rather than the deposi- 

 tion of strata which constitute the groundwork from which we 

 have to evolve the history of the Permian epoch so far as North 

 Yorkshire is concerned. From the Midland Counties north- 

 ward an escarpment of Permian beds margins the Carboniferous 

 deposits along the line of their eastern boundary. Through 

 West Yorkshire this escarpment is continuous and each of the 

 rivers, in its course from west to east, breaks through it. In the 

 south of the county it is usually several miles in breadth and in 

 one place it attains 450 feet in elevation above the sea-level. 

 At the south-west corner of the Ainsty the Magnesian Lime- 

 stone margins the Wharfe with cliff's at Thorparch and Newton 

 Kyme. Passing northward by way of Knaresborough and 

 Ripon it crosses the Yore half a mile below Tanfield Bridge. 



Feb. 1888. 



