72 R. M. Beeley — Ice-fioivs in the Trent Basin. 



Charnwood rocks. These had in many cases beau clearly dropped on 

 the bottom of the lake by shore-ice from the Charnwood Hills. 

 Indeed, Charnwood rocks are found many miles north of the Charn- 

 wood area in places to which glaciers could not apparently have 

 carried them. They were most likely spread abroad during the time 

 of the existence of this glacier-dammed lake. 



The return of colder conditions, on the passing away of the short 

 warm period during which the Quartzose Sand was formed, led 

 to the return of the ice from the west, and the Middle Pennine 

 Boulder-clay was spread over the earlier drifts. The ice of this stage 

 went a long way west, at least as far as, or even beyond, Lincoln. 



The Middle Pennine Boulder-clay is a very widespread deposit. 

 The ice-sheet in the Irish Sea Basin, in addition to reaching the 

 Trent Basin over the low watershed to the south-east, passed over 

 the high watershed at Dove Holes, near Buxton, flowed down the 

 Wye and Derwent Yalleys and joined the main ice-stream near 

 Derby. Boulder-clays of this age have been found near Bakewell, 

 where well-scratched and distant erratics are numerous. Another 

 patch of boulder-clay of this age is to be seen at Crich, I'esting upon 

 a glaciated limestone surface, the strise indicating a flow down the 

 valley. Erratic boulders and boulder-clay also occur on the limestone 

 area of the High Peak. The Crich deposit contains many distant 

 erratics, as well as large polished and striated boulders of mountain 

 limestone, etc. 



Following the formation of the Middle Pennine Boulder-clay, a 

 rise of temperature would seem to have come about, for the glacier- 

 lobe retreated to the westward. But this amelioration does not 

 seem to have stopped the flow of the ice from Scandinavia. This ice 

 then advanced over the Middle Pennine Boulder-clay and outwash 

 gravels, and laid upon them thick deposits of boulder-clay, silt, 

 gravel, and sand. The sand and gravel occur, apparently, at all 

 horizons in the Chalky Boulder-clay, but is most strikingly developed 

 towards the bottom and top. The lower deposit, the Melton Sand, 

 seems to have been deposited in open water. I never found any 

 evidence favouring the assumption that the easterly and westerlv ice 

 ever met. Indeed, the westerly ice would seem to have retreated 

 very rapidly indeed, and led to the formation of a glacier-dammed 

 lake in the south-westerly portion of the Irish Sea, before the 

 Scandinavian ice had reached its maximum extension. It was during 

 the maximum extension and retreat of the Chalky Boulder-clay ice 

 that the Chalky Gravel was formed. 



How far to the west the Chalky Clay and its associated deposits 

 extend beyond Burton-on-Trent I do not know. The water from the 

 glacier lake, however, seems to have been in communication with 

 the Irish Sea Basin lake at Rudyard, and to have overflowed into the 

 Severn Valley, probably by the low cut south of Henlev in Arden. 



It is probable that the time of maximum cold did not coincide with 

 the time of the maximum extension of the ice. Even in the case of 

 our winter and summer, the lowest and highest temperatures do not 

 coincide with the shortest and longest days. The warmest dav 

 occurs about a month after the longest day. Similarly, the greatest 



