248 PROCEEDINGS COTTESWOLD CLUB 1909 
area, between the coal-field of the Forest of Dean and 
that of the Bristol district; and although, higher up the 
valley, the position of the escarpment on one side is 
occupied by the Malvern Hills, as shown in the diagram 
fig. 4, the conditions between these hills and the escarp- 
ment on the other side of the valley were hardly, if at all, 
Fic. 4.—Diagram-section of a valley on an anticlinal axis. A, the outline of the Malvern 
Hills which occupy, in relation to the Severn Valley on one side, a position 
corresponding to the Oolitic escarpment on the opposite side. 
less favourable to denudation and the forming of a river 
valley than they are in the line of a complete anticlinal 
axis. 
The widely-accepted theory of the development of the 
Lower Severn, in accord with the teaching of Professor 
Davis, has been recently stated in the Victoria History of 
Herefordshire, Vol. I, and in the Proceedings of the 
Cheltenham Natural Science Society, Session 1907-8, 
p- 62: it is, briefly, this. A small stream flowing into 
the Bristol Channel, or, as it is expressed, “ starting from 
a strong tidal estuary,” “cut its way backwards, capturing 
the consequents which crossed its path one after another.” 
The meaning of this has been made so clear that I may 
reduce it to diagram form as in fig. 5. 
Let ABCD, Fig. 5, represent four streams flowing 
across the area now occupied by the lower Severn Valley, 
and E a stream supposed to be “working backwards” 
until it has successfully captured all four. The capturing 
stream E diverts into its channel all the water of the 
streams ABCD above the “elbow of.capture” and a 
portion of that below it, the course of which is reversed. 
