Correspondence — Mr. D. Mackintosh, 483 



and "continental" denudations and removals of rock by the sea, 

 " the present irregularities of the earth's surface are mere scratches ; " 

 and an abstract of a paper by Mr. Witchell on the Denudation of the 

 Cotteswolds. 



Mr. Witchell believes that the combes of the Cotteswold valleys 

 have been formed by the springs they contain. Before, however, 

 the occprrence of springs in combes can be regarded as furnishing 

 any evidence that the combes were excavated by them, it is neces- 

 sary that the following questions should be answered. Do the 

 springs along a line of escarpment occur generally at intervals such 

 as might lead one to expect to find them in the parts which run back 

 into combes ? Is there sometimes more than one spring in a single 

 combe ? Do sj^rings in combes occur on the sides, at the back, at 

 the mouth, or in apparently accidental positions? [I once saw a 

 subterranean stream, not far from Crickley, flowing out of the side 

 of a short valley, in such a way as to show that it could have had 

 little to do with the excavation of the valley.] Are not the springs 

 in some combes the indirect result of the surface-drainage of the 

 areas of the combes ? Is it a fact that all the Cotteswold combes 

 contain springs ? Supposing the connection between the Cotteswold 

 combes and springs to be so great as Mr. Witchell asserts, then the 

 dry combes of the Chalk and other districts could not have been 

 formed by springs, for it is as reasonable to believe that springs 

 have broken out in combes after their formation, as that springs have 

 disappeared from combes. With regard to the supposition that the 

 sea would not have selected the parts of escarpments containing 

 springs to hollow them back into combes, it may be remarked that 

 these are the parts which would have yielded most readily to its 

 undermining action, and the parts where coast-slips would have 

 chiefly occurred. I believe that the denudation of the Cotteswold 

 hills (which can only be thoroughly understood by considering it in 

 connection with other districts) has been effected as follows : — Tidal 

 and other currents must have furrowed the original table-land (if a 

 table-land free from considerable undulations ever existed) into 

 shallow passes^ — one side of these passes, owing to its being the 

 upcrop side, the side exposed to wind, or the side on which currents 

 chiefly impinged, was rendered steeper than the other, — while the 

 sea occupied the passes, coast-slips occurred on the parts moistened 

 and loosened by springs — the sea swept away the slipped debris, 

 cleared out and smoothed the irregular vacancies left by the slips so 

 as to give rise to the curvilinear hollows called combes. The drift 

 on the upper slopes of the Cotteswold valleys is of much the same 

 nature with that on the flat tops of the plateaux. It is just what 

 might have been left by currents, or waves acting under conditions 

 unfavourable to the rounding of stones. In many places it forms an 

 extensive and uniform covering or lining, which could not possibly 

 have been left by small streams; while I am prepared to prove, 



^ Both ends of these passes have since been deepened by streams, in many places 

 to a very great extent ; for atmospheric denudation is more active in some parts of 

 the Cotteswold district than in any part of South Britain with which I am acquainted. 



