HUGHES : IXGLEBOROUOH. 
331 
catenularia Linn., Or this actonice Sow. ; to these I may add a 
Petraia [Streptelasma) cequisulcata. Near Twistleton Manor House 
the Coniston Limestone is seen in a roadway very much crushed 
and traversed by veins of calcite. It has evidently been much 
altered here and has a brown, earthy character, being probably 
dolomitized. 
It crosses Dale Beck east of Twistleton Manor, but denuda- 
tion has cut it down so much that it is generally covered by the 
alluvial gravel, except after a great flood, when portions are for 
a time left bare, or where baked portions are preserved in contact 
with the dykes, which stand out in reefs and buttresses having 
the same trend as those seen in the Greet. 
A few small exposures among the roches moutonnees show 
that just south of Skirwith the same beds cross the eastern road 
to Chapel-le-dale and the stream below the farm. 
At the lower end of Crina Bottom, whose waters drain into 
Jenkin Beck, there are shales and bands of concretionary lime- 
stone which weather into light, porous, gingerbread-coloured rock 
by the removal of the lime. These beds apparently dip at a high 
angle, but this is not clear, as there are only small exposures, 
and the beds deviate somewhat from the normal strike of the 
Coniston Limestone Series in the adjoining area, running E.N.E. 
and W.S.W. They are probably near a crush. 
From this point for three miles to the south-west denudation 
has failed to reach down through the Mountain Limestone, on 
the upthrow side of the great fault, to the level of the Silurian 
and Bala. On the downthrow side of the fault the Mountain 
Limestone has nowhere been cut through. 
As we have seen (p. 134) the base of the Carboniferous rocks 
is reached at different depths dependent upon the character of 
the underlying rocks, and the Bala shales seem always to have 
suffered more erosion than any of the other pre-Carboniferous 
rocks of the district. Therefore they have generally a greater 
thickness of Mountain Limestone above them. These depressions 
caused a larger gathering of subterranean waters in the fissured 
limestone, and thus valle3's are apt to be opened up along them 
