32 PROC. COTTESWOLD CLUB VOL. Xlll. 



of time before the neck is cut through and the river 

 straightens itseH". 



One more future speculation may be indulged in. 

 The Carboniferous Limestone between Tintcrn and 

 Chepstow acts as a kind of check to the outflow of the 

 Wye — the river cannot cut its bed down rapidly. Now 

 the Usk, on the west, has no such impediment to contend 

 with : it can lower its valley and drain the surrounding 

 country effectually. As it is, a tributary of the Usk rises 

 at Trellech, within a couple of miles of the Wye ; and as 

 the Old Red Sandstone will be denuded faster than the 

 Carboniferous Limestone, in time the Wye may find 

 prepared for it an easier course into the Usk than down 

 its own channel, a course which it will hasten to make 

 use of in flood time. 



Then it will soon make use of it regularly ; so that the 

 gorge of Carboniferous Limestone between Tintern and 

 Chepstow will be left like that at Cheddar, a dry, or 

 nearly dry, valley — the relic of a once existing river. 





