52 baker's north YORKSHIRE. 



Their Influence upon the Configuration of the Dales and Hill- 

 masses. — The results of these lithological differences are to be 

 found, not only in the modification which they produce upon 

 the general contour of the surface and the influence which they 

 exercise in determining the shape of the dales and the con- 

 figuration of the hill-masses, but they exercise also an influence 

 which is by no means unimportant upon the topography of the 

 vegetation. We will take the first question first and examine 

 their influence upon a large scale and then treat the matter in 

 its botanico-geographical bearings. 



The different beds and bands of rock have all since the 

 period of their original deposition been subjected to the influence 

 of energetic watery action. The glacial inundation must have 

 reached a height of at least looo feet above the present sea- 

 level, and that is only one flood amongst many. In almost all 

 the dales the strata upon the opposite sides of the dale corre- 

 spond to each other precisely. This correspondence is disturbed 

 by faults in Teesdale, Lunedale and Arkengarthdale, and by 

 smaller dislocations elsewhere, but as a rule our dales are dales of 

 denudation. In Wensleydale we have the same bands of lime- 

 stone in the fells upon both sides of the hollow with an 

 excavation between them which often reaches a mile in width 

 and a thousand feet in depth. In the dales of the Esk and 

 Derwent districts the sandstones of the Lower Oolite may 

 usually be seen above the shales of the Upper Lias upon both 

 sides at an equal elevation above the stream. And we find that 

 the general contour of the surface and configuration of the dales 

 and coast is very much to be explained by the fact that the 

 strata of different degrees of hardness have been unequally worn 

 away. 



Both upon the east and in the west in the hill country two 

 different types of scenery may be traced. The flat table lands 

 of the limestone hills contrast conspicuously with the irregular 

 undulations of the sandstone hills : the steep precipitous cal- 

 careous scars not less so with the irregular ' edges ' of freestone 



