HUGHES : INGLEBOROUGH. 
143 
These dales running north into the base of Ingleborough 
furnish clear examples of almost every type of river denudation. 
There are the rapids and waterfalls cutting back to alluvial 
plains over which streams wandered about, widening their valleys, 
but doing little to cut their beds deeper ; there are the lakes 
(however caused) being filled with alluvium and peat. 
Although they are on a small scale, all the most important 
phenomena are represented here, and thus we have as part of 
Ingleborough examples of the sea-plain, of the bed-plain, and of 
the river-plain all clearly defined and accessible. 
I have not touched upon the effect of glacial action on 
these features which are primarily due to other causes, but we 
must remember that the ice of the glacial epoch gathered on the 
heights of the old sea-plain, crushed its way over the Mountain 
Limestone ledges round the flanks of Ingleborough, and, later on 
still, pushed long fingers of ice down the deeper valleys, leaving, as 
it receded, the moraines which still determine or modify denudation. 
I cannot name any district in which the ordinary details 
of denudation and many of its more exceptional operations can 
be so well studied as within the area which we have included 
under Ingleborough or in its immediate neighbourhood. 
The condensation of the moisture of the winds on the cold 
rocks working where no rain can reach ; the action of water 
more or less charged with acids on the limestones ; the fantastic 
forms which are thus produced ; the effect of this action on a 
larger scale in the formation of pot-holes, and of underground 
channels and of valleys by the falling-in of caves ; all claim 
the attention of the geological student. The breaking up of 
great masses of jointed rock under the influence of frost and 
the masses that in the thaw are carried over the frozen snow 
that fills the place where the talus should rest, and form 
crescentic masses lying some way in front of the cliff; the cut- 
ting back of gorges by the removal of block after block, first 
detached by complex denudation, then lifted out of their bed 
by the hydrostatic paradox and hurled over the edges of the 
cliff ; all these, too, can be studied here. 
