252 A. Geilde — Oti Denudation now in Progress. 



annual quantity of detritus carried to the sea is equal to the yearly 

 loss of -\ of a foot from the general surface of the country. The 

 valleys, therefore, are lowered by ~ of a foot, and the more open 

 and flat land b}'- ^^ of a foot. At this rate it will take' 10,800 years 

 before the level ground has had a foot pared off its surface, while in 

 1200 years the valleys will have sunk a foot deeper into the frame- 

 work of the land. By the continuance of this state of things a 

 valley 1000 feet deep may be excavated in 1,200,000 years. We may 

 take other proportions, but the facts remain, that the country loses 

 a certain ascertainable fraction of a foot from its general surface per 

 annum, and that the loss from the valleys and water-courses is much 

 larger than that fraction, while the loss from the level grounds is 

 mucli loss. 



It seems an inevitable conclusion that those geologists who point 

 to deep valleys, gorges, lakes, and ravines, as parts of the primeval 

 architecture of a country, referable to the upheavals of early geolo- 

 gical time, ignore the influence of one whole department of natural 

 forces. For it is evident that if denudfttion in past time has gone 

 on with anything like the rapidity with which it marches now, the 

 original irregularities of surface produced by such ancient subter- 

 ranean movements must long ago have been utterly effaced. That 

 the influence of these underground disturbances has often con- 

 trolled the direction in which the denuding forces have worked, or 

 are now working, is obvious enough; but it is equally clear that 

 under the regime of rain, frost, ice, and rivers, there must have 

 been valley-systems wherever a mass of land rose out of the sea, 

 irrespective altogether of faults and earthquakes. No one who has 

 ever studied rocks in the field is likely to overlook the existence of 

 faults and other traces of underground movement. But he meets 

 everywhere witn proofs of the removal of vast masses of rock from 

 the surface, which no amount of such mo^'cments Vv'ill explain. At 

 their present rate of excavation the '' gentle rain from heaven," and 

 its concomitant powers of waste, will carve out deep and wide 

 valleys in periods which, by most geologists, will be counted short 

 indeed. And if an agency now in operation can do this, it seems as 

 unnecessary as it is unphilosophical to resort to conjectural cataclysms 

 and dislocations for which there is no evidence, save the very phe- 

 nomena which tliey are invented to explain. 



In reference to the origin of the present configuration of the earth's 

 surface, attention has recently been more specially drawn to the 

 Highlands of Scotland as retaining in great measure the " aboriginal 

 outline" impressed upon them by ancient upheavals and fractures. 

 To this subject it may be jDroper to return on another occasion. In 

 the meantime it may be remarked that those subterranean move- 

 ments nmst have happened previous to the formation of the Old Ked 

 Sandstone. If, then, the present outlines of the surface are, in the 

 main, older than that formation, it is evident either that the time of 

 the Old Ked Sandstone cannot be removed by any long period from 

 our own day, otherwise these outlines would have been obliterated 

 by atmospheric waste, acting even no faster than it is doing now ; 



