76 THE DENUDANTS, OR CARVERS OF THE 



take place, except the small erosion that is effected 

 on the banks of streams, rivers, and lakes. Further- 

 more, most of the detritus carried down from the 

 uplands lodges on the lowlands, so that only a small 

 portion of the particles denuded on lands bordering 

 the coast-line, can be carried out and deposited in the 

 sea. It may be also pointed out that the present 

 conditions of this island are not more favourable 

 than those last preceding; as it is known, from 

 geological and historical records, that in ages past 

 the country was a vast forest. 



The principal work of meteoric abrasion is to 

 disintegrate rock surfaces, thus preparing matter to 

 be carried away by wind, rain, rivers, ice, and the sea. 

 Sometimes, however, it quarries out masses, as 

 alternations of heat and cold will open cracks and 

 joints in rocks. These may become filled with wedges 

 of water or ice, and such wedges will shift and dis- 

 place masses of matter ; but, strictly speaking, such a 

 denudation is not solely due to meteoric abrasion, as 

 without the cracks resulting from the contraction of 

 the rocks the denudant could not have quarried the 

 rocks. Our former colleague, Prof. T. M. Hughes, 

 of Cambridge, thus describes the denudation of the 

 cliffs at Sheppy, Kent, England : 



" In the hot weather the surface of the ground is 

 cracked from the shrinkage of the clay, and the 

 cracks are seen along the highest ground as gaping 



