586 DENUDATION AND SCENERY. 



to their inclination and crumpling, as well as to the faults, fissures 

 and joints by which they are affected ; for these latter form lines 

 of weakness that may initiate the direction of the drainage.^ 



In mountain groups the strata, as a rule, are much folded and 

 contorted, forming ridges and irregular features, as in North Wales 

 and in the Lake District ; in escarpments the beds, as a rule, are 

 gently inclined, as in the Chiltern Hills : while in table-lands and 

 plains the rocks are usually flat and undisturbed, as in portions 

 of the moorlands of East Yorkshire, and in Salisbury Plain. The 

 connection between scenery and disturbance is, however, varied. 

 Synclinals are apt to resist denudation, while anticlinals may have 

 had broken and fissured summits readily acted upon by atmospheric 

 agents : so that, as in Snowdon, we sometimes find the higher 

 grounds to be formed by what was geologically a depression, while 

 tracts originally elevated have been converted into valleys, as we 

 find them (more or less modified) in the valley of the Weald and 

 in the vale of Wardour.- Valleys of this description, like that of 

 Kingsclere and Burghclere in Hampshire, were originally described 

 as 'Valleys of Elevation.'^ (See pp. 390, 426.) 



Scenery is thus due to many causes : to the accumulation of the 

 strata, their consolidation, and the occasional intrusion of eruptive 

 rocks ; to their upheaval and disturbances ; and to erosion at 

 various periods. 



The features that were produced in Palajozoic times have all 

 been more or less eflaced. The very oldest rocks, so altered that 

 we scarce know their real origin, and the earliest sands and mud, now 

 hardened into quartzite and slate, are remnants of old sea-bottoms 

 and of old lands whose extent can but vaguely be conjectured. 

 The Cambrian and Silurian rocks, which form so much of Wales 

 and the Lake District, were folded and upheaved before the 

 Carboniferous rocks were laid down, and probably in Devonian 

 times, for in North Wales and Cumberland there is a marked break 

 between the uppermost Silurian rocks and the Upper Old Red 

 Sandstone or basement Carboniferous conglomerate ; and these 

 old rocks, hardened as they must have been, have stood up in 

 many places as land-tracts during later periods, yielding up 

 material time after time, so that they are truly but weather-beaten 

 relics of much more extensive areas.'' 



^ See G. H. Kinahan, Valleys and their Relation to Fissures, Fractures and 

 Faults, 1875. 



2 See Topley, G. Mag. 1866, p. 438 ; D. C Davies, P. Geol. Assoc, iv. 340. 



3 Buckland, T. G. S. (2), ii. 119. 



^ The student who desires further information on the ancient physical geography 

 of the British Islands, should consult E. Hull, Contributions to the Physical 

 History of the British Isles, 1882 ; A. C. Ramsay, Physical Geology and 

 Geography of Great Britain, ed. 5, 187S ; R. A. C. Godwin-Austen, Q. J. xii. 38; 

 P. M. Duncan, Formation of Main Land-Masses, Proc. R. Geogr. Soc. xxii. ; 

 J. Geikie, Geographical Evolution of Europe, Scottish Geogr. Mag. 1886 ; 

 and J. J. H. Teall, G. Mag. 1880, p. 349. For topographical descriptions and 

 references, see W. J. Harrison, Geology of the Counties of England and of North 

 and South Wales, 1S82. 



