EARTH-SCULPTURE BY RAIN. 147 



Similar effects of rain are visible to a greater extent on the bold 

 crags, like Almias cliff and Brimham rocks, which crown the summits 

 of so many hills of north-western Yorkshire, from, some of which the 

 Devil's Arrows were obtained. 



In the valleys of Switzerland (Sarnen) blocks of limestone, which 

 have fallen from the mountain sides, have been furrowed in the same 

 way since their descent. 



On Rocky Escarpments and Floors. The carboniferous limestone 

 of England has been little employed in building, except partially in 

 old castles, where it seems durable. But those who know the magni- 

 ficent ranges of scars which gird the hills of Derbyshire and West- 

 moreland, will acknowledge that few rocks seem more likely to endure 

 the rage of the elements. Yet, on close inspection of these giant cliffs, 

 the dry and bleached aspect, and smoothed angles, show plainly wasted 

 surfaces. Those who have stood on Doward Hill, near Monmouth, 

 to contemplate the rain-furrowed white limestone there, will not need 

 another example. In the north of England analogous and more re- 

 markable instances present theniselves in the wide limestone base of 

 Ingleborough, and in Hutton roof crags near Kirkby Lonsdale. 



The vast limestone floor which supports the cone of Ingleborough 

 is marked in all directions by natural fissures, and divided into com- 

 partments like a map. 



If one of these compartments be examined in the western part of 

 the mountain, its surface will be found scooped into little hollows 

 which unite into a common channel, and terminate by indenting the 

 edges and furrowing tlie sides of the fissure. They are, in truth, 

 valleys in miniature, produced separately Ly the drainage of the 

 several blocks. 



The mere decomposing effect of the atmosphere produces on the 

 edges of the stone a different effect, by wearing away the softer 

 laminae, but the smooth surface of the miniature valleys, their regular 

 descent, winding course, and union into a common channel, show that 

 they were fashioned by the repeated fall of rain. 



This scar is nearly level, but in Hutton roof crags we have an 

 opportunity of tracing the rain-channels over an iinmense surface of 

 bare limestone rocks lying nearly level on the hill-top, but sloping 

 rapidly down the sides to the east and south. On the level top of 

 the hill the stones are variously worn in hollows and grooves irregu- 

 larly united and running in different directions, according to little 

 variations of the groun'd ; but on the steep east and south slopes the 

 channels are extended into long furrows, which, uniting at acute angles, 

 enlarge, widen, and descend the hillside in lines following exactly 

 the declination of the rocks, and stopped only by few and distant 

 fissures, beyond which other systems of concurrent grooves begin. 



Rain-Channels like Miniature Valleys. It is impossible by draw- 

 ings or descriptions to convey such an idea of the appearances of the 

 Hutton roof crags, as to awaken in others the impressions which 

 are fixed for ever in the mind of the observer. The astonishing resem- 

 blance which these little rain-channels present to the great system of 



