﻿CXViii PEOCEEDINGS or THE GEOLOGICAL SOCIETY. [^aV I908, 



So convincing an argument ought to have settled the question, 

 and to have started an investigation of the valley-systems 

 of this country, which, however, was not begun until forty 

 years later. Scrope's testimony had indeed the effect of sending 

 Lyell and Murchison in company to Auvergne, with his volume 

 rn their hands. So impressed were these observers with the 

 cogency of the evidence there conspicuously presented, that one of 

 the first things they did, after the opening of the next session 

 of the Geological Society, was to read a conjoint paper ' On the 

 Excavation of Valleys as Illustrated by the Volcanic Eocks of 

 Central France.'^ But the impression then produced on their 

 minds did not permanently convert either of them to a belief in 

 the paramount influence of subaerial denudation in the formation 

 of valleys. Scrope, on the other hand, followed up his observations 

 in Auvergne by extending them into other parts of the Continent, 

 where he obtained fresh confirmation of his views. In the spring 

 of 1830 he laid before our Society another excellent contribution 

 to the subject, in the form of a paper ' On the Gradual Excavation 

 of the Valleys in which the Meuse, the Moselle, & some Other 

 Hivers Elow.' - 



There seems to have been an invincible repugnance to admit 

 that what seems to be so feeble an agent as running water could 

 of itself be sufficient to carve deep and wide valleys out of solid, 

 undisturbed rock. Hence, even when denudation was admitted as 

 a more or less important factor in the process, there was a general 

 conviction that it must have been largely aided by underground 

 movements ; that valleys must at least have been initially determined 

 by lines of fault ; and thus that the action of any superficial agencies 

 must always have been guided and controlled by the structure 

 of the terrestrial crust. This prevalent opinion was expressed by 

 Hopkins, in his well-known paper * On the Geological Structure 

 of the Wealden District.' ^ He believed that the area of the 



1905, pp. 159, 247). Commenting on the paper by LyeU & Murchison, above 



cited, Fitton, in his Presidental Address for 1829, remarks in a footnote that 

 Playfair seems to have been unaware of the existence of the ' Essai ' by 

 Montlosier, who had been cited as the original propounder of the subaerial 

 erosion of the Auvergne valleys. But Fitton himself does not appear to have 

 been acquainted with the still earlier writings of Desmare t, which were 

 certainly known to Montlosier. 



1 Proc. vol. i, p. 89. The paper was read on Dec. 5th & 16th, 1828. 



2 Ibid. p. 170. 



3 Trans, ser. 2, vol. vii, p. 1. Although read to the Society in 1841, this 

 paper was not published until 1845. 



