6o6 DENUDATION AND SCENERY. 



of contact, marking the progress of disintegration. In size it is about 17 feet in 

 length and 32^ in circumference about the middle part ; the weight appears to be 

 about 65 tons. There are 7 logan rocks in the parisli of Zennor.^ 



The various Tors of Cornwall and Dartmoor are similar exhibitions of the 

 weathering of Granite. The Cheesewring occupies the highest ridge of a hill to 

 the north of Liskeard, and this curious pile is about 15 feet in height. Helmen 

 Tor, on Dartmoor, is a rugged hill composed of blocks of granite, several of 

 which rock with ease ; there are also the Ripon Tors, and Hey Tor near Bovey 

 Tracey, which is very conspicuous from the country around Torquay and Newton 

 Abbot. 



Small ' Rock-basins ' occur on many of the Tors and isolated masses of granite 

 on Dartmoor, and these (which have been attributed to the Druids !) are probably 

 due to atmospheric action, which commenced in irregularities on the surface of the 

 granite, and may have been assisted by a spheroidal structure in the rock, as well 

 as by the friction of loose fragments of quartz and felspar.- In the Scilly Isles 

 there are many remarkable forms known as the Devil's or Giant's Punch Bowl on 

 St. Agnes, and the Kettle and Pans on St. Mary's. ■' 



Remarkable weathered rocks have been formed in the Millstone-grit, as at 

 Brimham Crags in Yorkshire, and the Hitching Stone on Sutton Moor, near 

 Keighley.* (See p. 170.) The " Buckstone," near Monmouth, is a huge rock 

 formed of Old Red Sandstone, which had become a rocking-stone by continual 

 waste of its base of attachment : it was unhappily thrown down in 1885.^ Some 

 prominent bosses of rock may have been in part formed by the action of Blowing 

 Sand.*' 



The influence of atmospheric agents on sandstone cliffs is well shown in the 

 Midford Sands at Bridport Harbour, in the New Red Sandstone of Dawlish and 

 Teignmouth ; while the Valley of rocks near Lynton is formed in hard Devonian 

 rocks. (See p. 125.) The weathered rocks near Tunbridge Wells have been 

 previously mentioned (see p. 363), and also the Agglestone, near Studland, which 

 is an isolated remnant of Lower Bagshot Beds, locally hardened. (See Fig. loi, 

 and p. 444.) 



We have attempted to describe the origin of the principal 

 physical features of our country and some of its minor features. 

 We have seen that the past is so intimately linked with the present, 

 that the modern aspects of the land form but the latest chapter in 

 the series of geological events. But while the present contours 

 have been marked out by various physical agents, to them alone 

 our scenery is but partially due, for without Nature's clothing the 

 aspect would indeed be bare and desolate. 



We have noted the great influences at work during the Glacial 

 Period, together with the extensive accumulations then spread over 

 the surface of the country, that have tended so much to diversify 

 the soil rather than the contour. To changes that occurred 

 towards the close of this period, we attribute the banishment of 

 many of the characteristic Pleistocene forms of animal- and plant- 

 life from the surface of our land ; but although various Mammalia 



1 G. W. Ormerod, Q. J. xxv. 273 ; Dr. J. MacCulloch, T. G. S. ii. 66 ; 

 R. Hunt, Geol. and Nat. Hist. Repertory, i. 29 ; G. Mag. 1873, p. 317. 



- G. W, Ormerod, Q. J. xv. 16; Geologist, ii. 368; E. W. Brayley, Phil. 

 Mag. Nov. 1830. 



3'De la Beche, Report Geol. Cornwall, p. 451 ; J. Carne, Trans. R. G. S, 

 Cornwall, vii. 146. 



^ J. R. Daykns, G. Mag. 1879, p. 96. 



^ Phillips, Manual of Geology, 1855, p. 470. 



« A. H. Green, C. Le Neve Foster and J. R. Dakyns, Geol. N. Derbyshire, 

 p. 40 ; Hull and Green, Q. J. xx. 253. 



