SUMMITS OF DRAINAGE. 



43 



is 750 feet above the sea. But from And over's Ford, on the Coin, 

 540 feet above the sea, the road to Cheltenham passes over a com- 

 paratively low transverse neck of land, 600 feet above the sea, 

 through which, if the Severn Vale were full as once it was, it might 

 throw its stream into the drainage of the Thames. 



The summit of drainage between the Windrush and the Avon 

 is the high cliff-edge of the Cotswold, toward which, on the 

 eastern side, we rise by a long ascent, which continues to the very 

 brink of a steep descent. There is here in fact hardly any distinct 

 col or depressed passage across the summit, so that, like the Leach, 

 this may be regarded as purely a Cotswold stream, which has no 

 rain-channel connection with the feeders of the Severn. This 

 summit of drainage is, in some places, 900 feet above the sea. 



Very different is the case of the Evenlode, which collects itself 

 near Moreton-in-the-Marsh on a broad low summit only 450 feet 

 above the sea, meeting there a branch of the Stour. 



Meeting branches of the Avon of Warwickshire and the ISTen 

 of Northamptonshire, the Cherwell watershed is about 450 feet 

 above the sea. The Ray drains ground much lower, so that one 

 may pass out of this system into that of the Bedfordshire Ouse 

 by an easy summit, 300 feet above the sea. The Thame drainage 

 is passed at a height of 450 feet, and that of the Kennet at 550 

 feet. 



Diagram XII. Land submerged 250 feet. 



If now we represent on a map the condition of things when 



