22 



that, during the elevation of the hills, the tides, running up 

 narrow fissures, had produced the present configuration of this 

 portion of the Cotteswold range. 



The power of subaerial agents — of " Eain and Eivers " — had 

 not then been fully recognized, though their claims had been 

 forcibly brought forward by Colonel Greenwood in 1857, and 

 latterly by J. B. Jukes, Esq., in writing on the formation of 

 river valleys in the south of Ireland. From a most intimate 

 acquaintance with the Geology of the district, and from acute 

 observation and reasoning, Mr. Witchell has brought the 

 arguments in favour of subaerial denudation to bear, in a 

 powerful focus, on our Cotteswold Hills; and I, for one, have 

 to thank him for thus, as I believe, clearing up many of the 

 difficulties which presented themselves when the mode of the 

 formation of these valleys was attempted to be explained. 



There is always some danger of running from one extreme 

 to the other; and in calling in the aid of our new ally — subaerial 

 action — ^to account for the existing form of the earth's surface, 

 we may easily slight our old friends, marine and volcanic agents. 

 I trust, therefore, it may not be without interest if I bring 

 forward some of the restdts of an examination of the stratifi- 

 cation and general features of the district around Stroud — a 

 district which illustrates in a very striking manner the changes 

 which have been wrought in its physical features since the 

 primary deposition of the strata of which it is composed. 



On reference to the sketch map of the Kiver Frome and its 

 Tributaries, it will be seen that they carry off the rainfall of an 

 area twelve miles in extent from north to south, and eight miles 

 from east to west, — no inconsiderable portion of the Cotteswold 

 range. 



The peculiarities in the Physical Geography of this district 

 appear to be due — 



First. To the diversities of composition, and to irregularities 

 in the amount of the original deposition of the strata. 



Secondly. To inequalities of elevation or depression. 



Thirdly. To the removal of a large portion of these irregularly 

 deposited and irregularly elevated strata. 



