216 



although the formation of a combe is on a limited scale of 

 operations, the forces by which it has been efPected are 

 everywhere in a state of activity; and whUe a spring issuing 

 from a combe is not apparently a very powerful agent by which 

 the face of the country can be altered, the largest rivers are 

 only an aggregation of such springs, with the addition of 

 surface drainage. 



It has been frequently held by Geologists whose opinions are 

 entitled to great consideration, that the valleys of the Cotteswolds 

 were in earlier ages subject to marine influences, and that they 

 were, to a great extent, excavated either by the sea, as the 

 land first appeared, or by tidal rivers. * If I could find 

 any evidence at all in support of those opinions, I should not 

 presume to question them; but this I have been luiable to 

 do. No doubt, as the land was rising, the action of the waves 

 would tend to degrade the strata exposed to their force, the 

 softer portions of which would be swept away ; the debris of 

 the harder rocks would be rolled into boulders, or ground into 

 sand, and deposited in beds of drift and shingle. In course of 

 time the ground woTild probably acquire an undulating character, 

 and the STU^ace drainage would follow the coxu-se of the 

 luidulations, and so begin to form valleys; but the wash of the sea 

 would have a tendency to wear away all the inequalities of the 

 surface, instead of cutting deep channels, and would, therefore, 

 as regards the formation of valleys, be antagonistic to the action 

 of running streams rather than conducive to similar results. 

 It is by no means improbable, that prior to the upheaval of the 

 Cotteswolds, the Middle and Upper OoHtes extended much 

 farther westward than at the present time, and that they were 

 swept away by marine denudation; of coui-se it is impossible 

 to state where was the limit of these formations. 



In considering the denudation of the Cotteswolds on the side 

 of the Severn VaUey, we have before us the long escarpment 

 extending down the whole range, and presenting such striking 

 indications of a coast-line, that the existence of an arm of the 

 sea between the Bristol Channel and the ancient glacial sea, 



* Geol. of Cheltenham. Memoirs of GeoL Survey, &c. , &c. 



