LITHOLOGY, 53 



and gritstone. The sandstone hills are usually intersected by 

 branching rivulets which flow from their upper levels gradually 

 down their slopes into the low country : the limestone hills have 

 neither streams nor natural pools upon their surfaces, but the 

 glens slope suddenly and the water sinks through the calcareous 

 beds to gush out in large volume when it reaches some less 

 permeable stratum. The sandstone dales are open and irregular 

 with gradual slopes and undulated embankments : the limestone 

 dales are steep and narrow with sudden slopes and embankments 

 rising up like a wall upon each side to shut them in. 



It is in the east that the characteristic features of the hills of 

 the two types are seen most readily. We have there two ranges 

 of hills, one of which is fully 400 and the other 200 square 

 miles in area, which throughout their extent are composed, the 

 northern range of well-marked eugeogenous and the southern 

 mass of well-marked dysgeogenous materials: and most of the 

 main branches of the Derwent rise amongst the sandstone hills 

 and break through the limestone range before they enter into the 

 low country. As they pass from one range to the other the 

 change is so striking that it cannot fail to arrest the attention of 

 the most casual observer. The difference in outline of the two 

 kinds of hill may be well seen by looking up Bransdale or 

 Farndale from the vale of Pickering. We have then imme- 

 diately in front the flat plateaux and steep narrow dales of the 

 calcareous range with its steep escarpment towards the north 

 sweeping far away eastward ajnd westward, and beyond rise the 

 irregularly undulated masses of the heathery arenaceous moors 

 with the high anticlinal ridge to bound the horizon. In the 

 upper part of the dales the woods are scattered irregularly over 

 their slopes and are more frequently to be found along the 

 margins of the streams than anywhere else, but in their lower 

 portion the steep calcareous embankments are usually covered 

 thickly with wood from the edge of the plateau all the way 

 down the slope and the stream-side at the bottom of the dale 

 left free. The Bran and the Dove are both partly swallowed up 



April 1888. 



