^68 
HUGHES : INGLEBOROUGH. 
Round the south end of Ingleborough, even where the great 
masses of drift much obscure the section, numerous swallow 
holes still indicate the presence of the Mountain Limestone 
below, and reach it very near the top. In Fox Hole, for instance, 
north of Newby Moss, a little below the 1,500-foot contour, the 
dark grey, thin-bedded, fetid limestones, which represent almost 
the highest beds, are seen in the swallow hole. 
But the most remarkable pot holes seen on this side of 
the hill are the two known by the same name, which, however, 
I will distinguish as Long Kin East and Long Kin West (see 
map). 
Long Kin West is a chasm some hundreds of feet in depth, 
over which you can stand with one foot on one side and the 
other foot on the other side (see Plate XXXII., Fig. 1). 
Having followed the great swallow holes round the hill 
we again start from Clapham and if, instead of following the 
stream, we take a higher horizon in the limestone, some 200 feet 
above the base, along the road to Clapdale Farm, soon after it 
leaves the track to Know Gap, we see, by the roadside near 
Monk Hole, outcrops of limestone in which the conspicuous 
divisional planes are inclined at a high angle to the South. In 
the quarry above the road the same thing is seen, and used to 
be much better seen than it is now since the quarry has been 
freshly opened out. These divisional planes have been taken 
for bedding, but bands of fossils make it quite clear that they are 
only strong joints inclined at an angle of about 80° to the bedding, 
the true dip being here about 7° in a northerly direction. This 
strong jointing is more constant to the bedding than to the 
horizontal, and, therefore, farther up the valley, where the dip 
is lower, the jointing is higher, so that in Trowgill the rock is 
divided into great platy slabs, which, when looked at endwise, 
give the effect of basaltiform structure (see Plate XXX.). 
There are cases in which systems of cross joints of nearly equal 
strength do give the rock an irregular columnar structure. 
The Trowgill beds run up to about 1,000 feet above O.D. 
The precipice, as we have seen, is the side of a gorge probably 
due to a broken-down cave, though it happens to coincide with 
some of the most conspicuous " scars." 
