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to repeat the principle enunciated above, that the natural result of 
the denudation of an anticlinal of soft rocks folded over harder is 
to leave the central core or arch of older rocks asa ridge, whose 
summit axis corresponds with the axis of the anticlinal affecting 
the rocks undergoing removal. Under like circumstances a syn- 
clinal will of course weather into a depression. Both of these 
factors tend to produce important modifications in the courses of 
river valleys.) In the present case the Lune had cut through the 
covering of soft rocks down to a surface formed, over an area of 
several square miles, of the tough Silurian greywackés forming the 
Coniston Grits. For a time the stream maintained its course 
through these; being, however, modified in direction to some 
extent along the line where the soft strata joined the harder below. 
But the Third Plain at this part was shaped partly out of Car. 
boniferous rocks, which, long before, had been thrown into an 
anticlinal ; and had been already denuded through to below their 
base when the Third Plain was formed. The general direction of 
the particular anticlinal in question being north-westerly, or from 
The Calf, say, to Harrop Pike. The Carboniferous beds were 
therefore tilted to both the north-east and south-west of that axis. 
Another flexure crossed this above where Teba now is, slightly 
bending the Carboniferous strata downwards along a synclinal 
axis ranging south-westerly, or through Teba and Kendal.* The 
general result, so far as the present course of the Lune is concerned, 
was that the Carboniferous rocks enveloping the Howgill Fells 
tended, as fast as they were exposed, to recede towards the north 
the north-west and the west; and to leave behind them as they 
receded the old core of their anticlinal in a condition but little 
modified by the action of surface agencies. What is now the 
" Ressondale depression was in fact at first developed some miles 
farther up the slope to the south. Progressive denudation con- 
ducted it by degrees farther and farther down the northern and the 
Py 
is 
western slopes of the Howgill Fells, thereby exposing at each step 
more and more of the tough Silurian rocks, and removing more 
* The general direction of this synclinal axis is shown on the small contoured 
map annexed to the present paper, 
