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stream enters the lake during the time intervening between the date 
of formation of the lake and the present day. The alluvium about 
Grange, above Keswick, thus represents the amount of waste of the 
rocks of the Borrodale area since Derwentwater was formed. The 
small amount of waste in this case is probably due to the slow rate 
of destructibility of the tough volcanic rocks that occupy the area 
drained by the streams whose united waters enter Derwentwater at 
this spot. The much-more extensive waste of the Skidda Slate 
area is evidenced by the correspondingly larger accumulation of 
alluvium that has been brought down into the lower part of the 
same sheet of water by the Greta; an accumulation large enough, 
when united with the waste of the Newlands area, to fill up the 
whole of the lake at the part where Keswick now stands, and thus 
to divide a once-continuous sheet of water into the separate lakes of 
Derwentwater and Bassenthwaite. 
I have referred to these instances, in some detail, in order to 
make a comparsion with the larger quantity of alluvium spread out 
in the bottom of these Edenside Lakes ; a quantity much in excess 
of anything that can be pointed to in the Lake District proper. 
This excess is due partly to the more rapid rate of destructibility 
of the rocks of Edenside as compared with the rocks of the Lake 
District ; but mainly to the waste of the wide-spread deposits of 
glacial drift that spreads over nearly the whole of the lower ground 
drained by the Eden. 
It will thus, I think, be tolerably evident that the date of the 
Jakes of Cumberland and Westmorland, including, of course, that 
of the old lakes before us, though remote enough when measured 
be the standard afforded by history, cannot be very remote when 
estimated by a geological standard of time. What that date approxi- 
mately is I will now endeavour to show. It is tolerably clear at the 
Outset that each lake is very much newer than the valley wherein 
it lies; for the quantity of material heaped up in the rock basin 
_ forms but a very minute fraction of the total quantity excavated 
: during the formation of the valley itself. It is also clear, from the 
occurrence of mounds of glacial drift here and there throughout 
these Edenside lakes, and especially in the case of this Langanby 
