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4 number of wholly or partially filled-up lakes. Upon fell-tops one con- 
stantly met with tarns, filled-up with stream-borne detritus. Derwent- 
water and Bassenthwaite were at a former time one long sheet of water, 
but the River Greta had deposited a delta in its midst, and now the 
lakes were separated by some three miles of alluvial land. The same 
had occurred in the case of Buttermere and Crummock Water. 
Most of the Cumberland lakes yet examined seemed to be true rock 
basins ; they lay in rock hollows which had been rounded and scratched 
on all sides by the old glaciers, thus leading to the belief that these 
hollows, if not actually formed by the scooping power of the ice—as 
Professor Ramsay’s theory suggested—had at least been deepened by 
it. The terminal moraines often formed a marked feature in the 
scenery, as above Seathwaite, on the east side of Honister Pass, at the 
- head of Langdale, and several other places. At the head of Ennerdale 
Valley they were particularly striking—so much so as by some to have 
been taken for innumerable tumuli. 
The oldest rocks in the district were the Skiddaw slates; these 
were very ancient finely stratified mud rocks, containing, in some 
places, remains of marine shells, worm tracks, fucoids, shrimp-like 
crustaceans, and graptolites. These ancient mud deposits, however, 
had been hardened, altered, contorted, and cleaved. Their thickness 
__was very great and required an enormous period of time for their 
formation. The marine conditions which probably prevailed for this 
long time over the district were closed by a great series of volcanic 
eruptions, at first submarine, the ashes ejected being stratified beneath 
the sea, and the lavas flowing over its bed. Very probably some areas 
_ of dry land were then formed by the accumulation of volcanic material, 
aided, perhaps, by the elevation of the sea bottom. 
The total absence of ordinary marine sedimentary deposits, and of 
any traces of fossils in the whole of the great thickness of ashes and 
_ lavas now forming the mountains of Borrowdale would seem to indi- 
cate that much of the material must have been ejected upon dry land, 
and parts of it, perhaps, deposited in large crater-lakes ; for while 
= there were great masses of unstratified or but rudely stratified ashes 
and coarse breccias associated with the lava-flows, there were also 
_ many intercalations of exceedingly fine-bedded ash, apparently depo- 
_ sited beneath water of some kind. On the close of the volcanic activity 
the district was again sunk slowly beneath the sea, and the various 
_ limestone, sandstone, and shale beds of the Upper Silurian age were 
deposited unconformably upon the great thickness of volcanic material. 
_ The remains of these rocks might now be studied south of: Coniston 
_ and Windermere, 
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