HILLS AND VALES. 589 



instances choked up and obliterated — some of these in course 

 of time have been re-opened, in other cases the drainage formed 

 new and independent channels. Thus, Mr. Mellard Reade has 

 shown that the Mersey between Warrington and New Brighton 

 runs over an old Pre-Glacial valley now filled with later Drifts.^ 

 On the whole, their distribution gives a clue to the fact that the 

 more marked features of our country were sketched out in Pre- 

 Glacial times, although the minor features have been very much 

 altered by the varying character of the superficial deposits : and 

 this is especially the case in Norfolk and other eastern counties, 

 where the Pre-Glacial scenery has been almost entirely eftaced 

 by accumulations of Drift. 



Thus the building up of our land has been a long and compli- 

 cated process, while the scenery that has resulted is naturally varied. 

 The principal features presented by each formation have been 

 previously noticed, and so marked are the relations of the rocks 

 to hill and dale that a geological map conveys to the geologist 

 a very good idea of the physical features of a country. 



In illustration of this subject it may prove useful to give the following classifi- 

 cation of Hills and Vales : — 



HlLLS.^ 



The Primary or Palreozoic ranges would include the following : — 



Cheviot Range (Lower Carboniferous and Igneous) : Cheviot, 2767 ; Peel 

 Fell, 1964. 



Cumbrian Mountains (Cambrian and Igneous) : Scawfell Pikes, 3229 ; 

 Helvellyn, 31 18; Skiddaw, 3054; Saddleback (Blencathra), 2847. 



Cambrian M(JUNtains (Cambrian and Silurian) : Snovvdon, 3571 ; Carnedd 

 Llewellyn, 3469 ; Cader Idris, 2959 ; Plynlimmon, 2463. 



Pennine Chain (chiefly Millstone Grit and Lower Carboniferous rocks on 

 Silurian, extending from the Cheviots to Staffordshire and Derbyshire): 

 Cross Fell, 2927; Whernside, 2384; Mickle Fell, 2580; Ingleborough, 

 2361 ; Pendle Hill, 1831 ; Penyghent, 2270 ; Kinderscout, Peak 

 district, 1981. 



Isle of Man (Cambrian), Sneifeldt, about 2000. 



Loiigmynd (Cambrian), 1674. 



Caradoc Hills (Cambrian and Igneous), 900 to 1200. 



Wrekin, Shropshire (Igneous, Archcean, Cambrian), 1320. 



Lickey and Clent Hills, Worcestershire, (Cambrian, etc.), 900 to 1028. 



Ahberlcy Hills, Worcestershire (Cambrian, etc.), 900. 



Malvern Hills, Worcester Beacon (Gneiss), 1396. 



May Hill (Silurian), 965. 



Charnwood Forest, Leicestershire (Archcean, Igneous, etc.), Bardon Hill, 852. 



Clee Hills, Shropshire (Basalt and Coal-measures, etc.) : Brown Clee, 1805 ; 

 Titterstone Clee, 1750. 



Vans of Brecon and Black Mountains, Brecknock Beacon (Old Red Sand- 

 stone), 2S62. 



Mendip Hills, Blackdown (Old Red Sandstone), 1067. 



Z r Devonian Ranges: Quantock Hills (Devonian), Will's Neck, 1262; 



w z Exmoor (Devonian), Dunkerry Beacon, 1690 ; Dartmoor 



> 2 i (Granite), Yes Tor, 2050 ; Amicombe Hill, 2000 ; Cawsand 



g(j Beacon, 1792. 



O ^ Cornish Highlands {Gvdimie) : Brown Willy, 1368; Rough Tor, 1298. 



^ Proc. Liverpool G. S. 1S72, Q. J. xxxix. 84, Proc. Liverpool Lit. and 

 Phil. Soc. 1872, 2 The heights are given in feet. 



