604 DENUDATION AND SCENERY. 



instanced the great waterspout of Hardra Foss near Hawes in 

 Yorkshire.^ 



The Scale Force, Cnimmock Water (known as the ' Queen of Waterfalls '), 

 the Stock Gill, Ambleside (' the gem of the Lake District '), and the Lodore 

 Falls, Borrowdale, near Keswick ('the English Niagara'), are due to streams 

 gushing down the mountain-sides over rocks of varying hardness. 



The ' Chines ' of the Isle of Wight, and the ' Bunnies ' of Hampshire, are 

 gullies which have been formed by the action of springs in making their way over 

 the soft strata of the cliffs into the sea. Mr. J. S. Gardner says the sides of some 

 of these gullies are upwards of loo feet high, and of most picturesque appearance ; 

 the ridges separating them, formed by snow-white sand, look quite Alpine with 

 their sharply-cut peaks ; while the ribbon-like and netted surface, caused by 

 weathering, produces a singular and striking effect.- On the Dorsetshire coast at 

 Golden Cap, and on the Norfolk coast, near Trimingham, deep gullies may also 

 be seen. 



The Tynedale escarpments and Yorkshire Dales were formed for the most part 

 in Pre-Glacial times by subaerial agents, although the prominent rock-features have 

 here and there been much modified by Glacial action. •* Deep semicircular recesses 

 known as Coums, Corries or Cirques, are found in most glaciated mountain 

 districts, and, in Mr. Goodchild's opinion, they may have been formed by the 

 eddying of ice.* 



In Limestone-districts, especially in the Carboniferous Limestone of Derbyshire, 

 Glamorganshire, and Somersetshire, the power of rain-water holding carbonic 

 acid is very great in dissolving the rock and forming caverns (see p. 540), and 

 it has been shown that some of the dales and ravines may have originated from 

 them.^ In any case these deep valleys have been formed in part by the 

 dissolution of the rock, and by streams, assisted by the mechanical action of frost. 

 Dove Dale, the Winnats (Windgates), near Castleton, and Gordale,'^ are well- 

 known features in the Limestone districts. The course of the rivers underground 

 through swallow-holes has been before alluded to, and the material they would 

 thus remove cannot be inconsiderable. (See p. 532.) At Caldbeck, in Cumber- 

 land, there is a spot known as the Howk, where the river has made a passage 

 through a thick limestone, so as to form a natural bridge ; this overlooks a 

 waterfall. 



The origin of the narrow winding gorge in the Carboniferous Limestone 

 at Cheddar has been a source of some discussion. The popular notion of a rent 

 or violent disruption is at once disproved by a glance at the dip of the strata, 

 which is regular on both sides of the chasm, while the idea that the sea was the 

 agent is also an assumption unwarranted by the nature of the gorge itself. That 

 the Cheddar Cliffs originated in a fissure or cavern in the Carboniferous Limestone 

 may be safely assumed. The dips in the Limestone strata, taken by Mr. J. H. 

 Blake, show a trifling variation on either side of the gorge, on the one side from 

 19° to 24°, and on the other from 15° to 23° ; all are in the same direction of south, 

 or a few degrees east of south. One fact that will immediately strike an observer 

 is, that nearly all the material removed has been taken from one, the northern side 

 of the ravine. (See illustration, p. 30.) This is important, for it demonstrates 

 that the dip of the beds exercised a great influence upon the formation of the cliffs, 

 of which the highest point is about 420 feet. The fissure originally would become 

 a line of drainage, and the water running through it, partly underground, would, 

 not only by mechanical action, but also by chemical agency, dissolve and wear 

 away the limestone. Frost, too, is an active agent in disintegrating fragments 

 frona the sides of the ravine ; and (on account of the southerly dip) on the 



1 T. G. S. (2), iv. 73, 89. 



* Q. J. x.xxv. 220. 



3 Hugh Miller, jun., Nat. Hist. Trans. Northumberland, 1880, vii. 



* J. G. Goodchild, G. Mag. 1S75, PP- 323, 356, 486; W. Gunn, G. Mag. 

 1876, p. 97. 



" J. Phillips, G. Mag. 1S64, p. 230 ; Dawkins, Id/J. 1865, p. 81. 

 '' P. Geol. Assoc, vii. 436. 



