550 Rev. W. Lower Carter — Olaciation of Don Valleys, etc. 



of drift as the relics of moraines, and therefore as indications of 

 periods of rest in glacial movement, I have attempted to map out 

 the lakes tbat would be produced at the different positions of the 

 ice-front, and have examined the watersheds to see if overflow 

 channels existed such as would be necessary to drain such lakes. 

 The whole has been plotted out on the 6-inch contoured maps, by 

 which the results have been carefully tested, and a series of lakes 

 made out discharging successfully over cols from 175 feet to 335 feet 

 above O.D. These overflow valleys are not of the type so character- 

 istic of Cleveland and the Cheviots. The long period of subaerial 

 denudation to which they have been subjected has worn back their 

 sides so that they are now V-shaped, but they are streamless 

 either in whole or in part, and often the nearest streams cut across 

 their ends. 



In spite of this weathering back there has probably been little 

 alteration of their level, and their present levels may be taken 

 approximately as those of the Glacial Period. Some of them are 

 strike-valleys formed by the denudation of the shales between the 

 outcrop of a bed of Carboniferous Sandstone and the dip slope of 

 a lower grit. The objections against such valleys as overflows have 

 been carefully considered, but as the movement of the ice seems to 

 have brought its margin parallel to the general strike of the Coal- 

 measures of this area, it is natural that the deflected drainage should 

 sometimes escape by such routes. In considering the course of the 

 first glacier, it seems probable that it would dam up the Dearne at 

 Ardsley and form a lake overflowing by the Stairfoot valley at 

 175 feet. A forward movement would carry it to the Wombwell 

 ridge, and the overflow would be by the Wombwell and Svvinton 

 strike-valleys. Further south the ice would j^robably abut against 

 the projecting spur of the 350-foot contour west of Rawmarsh, and 

 hence would form a lake about that level stretching up to Elsecar, 

 Cawthorne, and Bretton. In searching the watershed for a possible 

 overflow for such a lake, a narrow cut through the 350-foot contour 

 was found at the head of the Wentworth Woodhouse valley, sloping 

 back to the 400-foot contour on each hand, and with a little stream 

 running across each end at right angles to the direction of the col. 

 By this valley at 335 feet the Elsecar lake would be discharged into 

 a smaller lake held up by the ice in the Wentworth Woodhouse 

 valley. When the ice laid down the Masbrough and Sitwell Vale 

 patches of drift the Rother valley would be blocked, and the glacial 

 drainage would be discharged round the lobe of ice by channels at 

 Greasborougli and Sitwell Vale at 275 feet, and thence into the Don 

 by the Hooton Roberts valley (180 feet). A slight forward move- 

 ment of the ice to the gravel patches east of Hooton Roberts would 

 close that valley and cause the drainage to discharge by a col on 

 Conisborough Parks at 260 feet. 



The second glacier does not seein to have advanced far beyond 

 the curved line stretching from Barnsley through Adwick-on-Dearne 

 to Conisborough. This, by damming the Dearne at Ardsley, would 

 re-form the Barnsley lake, discharging over the Stairfoot col at 



