THE ORIGIN OF DERBYSHIRE SCENERY. 



187 



attribute these cliffs to the long continued action of water aided 

 by the joints. These divisional planes, which are frequently 

 vertical, give entrance to water, and the rest is merely a matter of 

 time. Such cliffs as the High Tor at Matlock are excellent 

 examples. Here we see the process referred to going on. The 

 river has cut its channel from a level far higher than that of the 

 tops of any of the neighbouring hills. Let us take a retrospect. 

 When the rocks of the district rose above the level of the sea, the 

 surface of the land would most probably be approximately flat. 

 We may look upon the plateau of Kinder Scout as representing 

 the remains of this surface, although this has no doubt sustained 

 a certain amount of erosion. Fig. 5 is a diagrammatic repre- 

 sentation of the plateau, which consists of a coarse quartzose 

 sandstone — Millstone grit. The drawing gives such a view as 



Fig. 5. 



Diagram of Kinder Scout. 



would be obtained from a balloon at a height such that the 

 smaller details would disappear. It is about six miles long by 

 two miles broad, and is covered in many places by a bed of peat 

 about 12 feet in thickness. The strata of which it is formed are 

 approximately flat, forming the centre of a. long, low, anticlinal 

 curve. Upon its surface are many fine examples of sandstone 

 weathering, due in a large degree to the decomposition of the* 

 felspar, a constituent of the rock. 



Soon fallen rain would cut for itself channels in this " plane of 

 marine erosion," and the course of these channels would be, in 

 a very large measure, determined by the homogeneity or want of 

 homogeneity of the rock. An obstruction in the form of a 

 harder mass of rock would determine a bend, and this would, as 

 will be explained shortly, determine other bends, and the stream 



