Vol. 68.] GLACIATIOI^ OF THE T3L1CZ COMBE DISTEICT. 441 



(4) The Whicham-Yalley and Duddon-Estuary Lakes. 



When the Whicham- Valley ice broke connexion with the retreat- 

 ing lobe of the Irish-Sea ice, the valley, as explained above (p. 437), 

 became the site of a lake with an ice-dam at its lower end. 



The valley and lake formed a convenient place into which the 

 surplus material from, and moving along, the ice-front could be 

 shot ; and we consequently find that for more than a mile above 

 Silecroft the valley was filled from side to side with fluvioglacial 

 deposits, ranging from clay and silt to sand and gravel, and boulder- 

 beds (fig. 16, p. 442). 



The deposits, still covering half a square mile between Silecroft 

 and Whicham Hall, form a tract of typical humtuocky ground, the 

 higher parts of which fall from nearly itOO feet on the western side 

 of the valley to 100 feet along its central line. On the eastern side 

 they have been removed by the Whicham Beck, but some relics 

 were found above the 100-foot contour on the eastern side of the 

 intrusion at Mcle Wood. 



Sections show that there is a great deal of red sand, which at 

 times contains rolled lumps of red clay, or passes laterally into beds 

 of clay. In the centre of the area a thin bed of fine loose sand 

 overlay false-bedded sand dipping at 45° southwards. A neigh- 

 bouring section in clear red sand showed a similar dip. A gravel- 

 pit, a quarter of a mile south-south-east of Whicham Hall, is opened 

 in a vary roughly-stratified sandy and gravelly deposit of a morainic 

 character, dipping on the whole in a south-south-westerly direction. 

 It contains boulders which lie at all angles, as well as large lumps 

 of red boulder-clay stuck full of stones. Boulders of granite and 

 volcanic rock occur up to 18 inches in size, and also fairly large 

 pieces of red sandstone, slate, and shale. Stratified sand and gravel, 

 resting on Carboniferous Limestone, at the southern end of the 

 valley has false-bedded layers dipping south-eastwards. 



The floor of the Whicham Valley is covered by boulder-clay 

 (p. 410), which also rises a little way up both sides. Thus the 

 sand and gravels are flanked on each side by boulder-clay, and 

 probably also rest upon it. In the part of the valley which was 

 submerged the boulder-clay has been modified at the higher levels 

 by denudation and the formation of terraces, and at the loAver 

 levels by deposit. 



The terraces, or old beach-lines, which usually consist of flattish 

 ledges, with sloping fronts, covered by slaty shingle, occur at various 

 levels below the 200-foot contour, as shown on. the accompanying 

 map (fig. 1 6, p. 442). Near Whicham Hall there are three, the lowest 

 being on the 100-foot contour and the highest at about 180 feet. 

 The last-named can be traced, at intervals, round the northern end 

 of the lake and some distance down the eastern side. The 100-foot 

 terrace, when followed northwards, merges into the alluvium. 



The deposits between the 180-foot and the 100-foot beach-lines 

 consist of variegated (pale-grey, yellow, brown, and red) stony clay 

 and loam full of slaty debris, many of the fragments being striated. 



