﻿Yol. 64.] ANNIVEESAKY ADDEESS OF THE PRESIDENT. CXvii 



that these topographical features are the result of the erosive work 

 of the streams that flow in them. But this view, lacking as it did 

 the favourite paroxysmal relish which so gratified the taste of our 

 fathers, was generally looked upon as merely one of the speculative 

 vagaries of the Huttonian school. It was therefore, for the most 

 part, rejected in favour of some indefinite conception of a combi- 

 nation of underground movements with the excavating power of 

 great debacles of water rushing over the land. In the first paper 

 on this subject published by the Society, Buckland, in discussing 

 the valleys of Dorset and Devon, attributed their formation to the 

 erosive action of ' a violent and transient inundation.' ^ A few 

 years later he contributed a further paper ' On the Formation of 

 Valleys by the Elevation of the Strata that Enclose them.'^ The 

 argument from the nice adjustment of the valleys to the drainage- 

 system of a country, which Playfair had so eloquently urged, made 

 no impression on those who in this country discussed the subject 

 for many years after his time. One of the earliest English 

 geologists who realized its force was Scrope, who in this, as in 

 many other branches of geological enquiry, was much in advance 

 of his contemporaries. We find him remarking, as far back as 

 1825, that a convincing proof 



' of the slowness of the process by which many very considerable river-valleys 

 were excavated is their sinuosity. This character can only be accounted for by 

 a lent and gradual abrasion, and where this exists it is idle to talk of sudden 

 catastrophes, debacles, or deluges, as having been the excavating forces.' ^ 



This accurate observer was, moreover, the first geologist to lay 

 before English readers a detailed demonstration, from actual 

 concrete examples, that deep and wide valleys have been hollowed 

 out of the surface of the land by the long-continued erosion of 

 running water. Following the earlier investigations of Desmarest, 

 his luminous exposition and admirable sketches showed how 

 the valleys of Auvergne have been cut out of a series of 

 freshwater marls and of successive lava-sheets which lie at 

 different levels and belong to different periods of eruption.* 



1 Trans, ser. 2, vol. i, p. 95 : read April 1822. 



2 Ibid. vol. ii (1829) p. 119. 



3 ' Considerations on Volcanoes' 1825, p. 215. 



* In his ' Geology & Extinct Volcanoes of Central France,' of which the 

 first edition was published in 1826 and the second in 1858. I have elsewhere 

 called attention to the singular oblivion which fell on the work of Desmarest, 

 who was really the first to maintain that the valleys of Auvergne were carved 

 out by the streams which still flow in them (' Founders of Geology' 2nd ed. 



