HUGHES : INGLEBOROUGH. 
257 
mapped, remains there always like a bench mark with which 
you must make your levels always agree. 
Sections may be drawn from such a map when the contours 
are given and generalisations as to the persistence or variation 
of the deposits can hardly be studied without it. 
As a contribution in aid of such general or special studies 
I offer first a map on which the outcrops of the principal lime- 
stones are shown. I have also in some cases indicated the 
probable boundaries of other formations which are nowhere 
clearly seen on Ingleborough, when their existence is suggested 
by surface features or the course of underground waters. I have 
draAvn a few sections in which the superposition of those beds 
is more clearly shown in detail, and have pointed out where 
peculiarities of structure may be observed, and where fossils 
have been obtained at various important horizons. 
The Great Scar or Mountain Limestone. 
In the preceding part of this monograph I described the 
basement bed of the Carboniferous, emphasising what I had 
pointed out before (Vol. XIV., p. 134), that we have here to 
deal with one of the greatest breaks in the whole geological 
series. I pointed out the manner in which the pre-Carboniferous 
surface had been planed off, though nob everywhere so deeply 
as to have swept away all traces of ancient valleys or of the 
deposits which had been washed into them. Remembering 
that the Carboniferous sj^stem here rests on a Sea Plain or Base 
Level of Erosion, we turn with great interest to an examination 
of the character of the sediment that was first laid down upon 
it. Sometimes it is a limestone which rests on the Bala and 
Silurian rocks with practically no conglomerate at the base, 
as in the Keld Cave in Chapel-le-Dale ; but generally the lower 
beds are made up of fragments of the underlying rocks, and 
when these are derived from the Green Slate Series, or Silurian, 
they consist of angular chips. Higher up in the Carboniferous 
rocks these fragments are no longer seen, but bands and lines 
and scattered pebbles of quartz occur at various levels through- 
out the lowest beds of the Mountain Limestone — in Chapel- 
le-Dale generally up to 20 feet or so from the base, under Xorber 
