HUGHES : INGLEBOKOUGH. 
55 
The Austwick Grit A.C.2. 
By-and-by there was more sand than mud, and instead of flags 
with subordinate beds of sandstone, we find massive sandstones 
with a few thin shaly partings. The tough sandstones were not 
susceptible of the molecular rearrangement which produced 
cleavage in the flags and shales, and therefore, under the lateral 
pressure, they buckled up into huge folds which just here often 
happen to present the surface of the beds to denudation, as on the 
top of the anticUnal arch between Crummack and Xorber, so that 
they resist denudation both by their toughness, and their mode 
of occurrence. The movements of which we are speaking are 
pre-Carboniferous, and accordingly we find the basement bed 
of the Mountain Limestone abutting against the flanks of an 
ancient ridge of grey Silurian, the unyielding character of which 
undoubtedly affected the lower part of the Carboniferous to 
some extent during subsequent movements also. Crummack 
Dale has been cut out so as to expose again this undulating 
surface of Silurian, but how much it has been modified since 
the Carboniferous rocks were removed from above it, we cannot 
estimate with any certainty. From the evidence given above 
(vol. xiv., pp. 144, 145, Figs. 4, 5), in respect of the adjoining 
area on the South, it is probable that the bottom of Crummack 
Dale may very nearly represent the surface on which the' 
Carboniferous rocks were laid down, even allowing for the 
immense number of boulders which lie on the hmestone ledges 
near Norber, or are contained in the moraine mounds along 
the valley and open ground bej^ond. These are derived chiefly 
from the Austwick Grit. 
The Austwick Grit stands out in the craggy ground west 
and north of Studrigg, and crops out in rough ridges by South- 
thwaite Wood, White Stone, and less conspicuously along the 
great strath from Wharfe to Swarth Moor. It is again seen 
on the north side of the Austwick Beck Head anticlinal, running 
from W.N.W. to E.S.E. on Capple Bank, and faulted at its 
E.S.E. end against the Moughton W^hetstones, see Fig. 4, p. 57. 
In the adjoining valley it is well seen south of Crag Hill, where 
it is doubled up much in the same way as between Crummack 
