410 CARTER : THE EVOLUTION OF THE DON RIVER-SYSTEM. 
tableland, and the Rother wore its way along the line of the 
Permian escarpment until it tapped the feeder of the Moss on 
the one hand and Barlow Brook on the other (Fig. 9). 
Thus the whole of the drainage of the river south of Staveley 
was drawn northwards along the strike of the Magnesian Lime- 
stone, and discharged into the Ryton by Kiveton Gorge, the 
Poulter being left at Clowne as a beheaded remnant. A conse- 
quent feeder of Shire Brook at the same time was working its 
way back into the Treeton watershed to meet the feeder of 
Ulley Brook. In the course of time a third stage (Fig. 9, III.) 
w^as reached, when the combined efforts of Ulley Brook and the 
Rother cut through the Treeton watershed, and then the low 
level at which the Don ran. as compared with the Ryton, enabled 
it to capture the Rother and all its tributaries, leaving the 
Kiveton Gorge as a deserted channel and the Ryton as a be- 
headed remnant. 
The curious elbow at Staveley (Fig. 8) may be a later diversion 
due to the vigorous little stream which rises at Bolehill and 
Middle Handley, developing a little consequent along the strike 
of the Middle Coal Measures which tapped the Rother at Staveley, 
and brought it to Renishaw by a shorter cut. 
The author has not observed any examples of the diversion 
of streams by glacier action in the valley of the Rother. 
