CAVES AND CAVE DEPOSITS. 171 
the pholas-bored rock from that in which the holes are due to 
weathering. On the chemically-weathered surface the less 
soluble grains and bands stand out. This is a useful test. 
When any partly-closed cave is invaded by periodic rushes of 
rain-water, the débris is carried down from above through 
fissures, or washed in from the mouth, and so we find resorted 
drift and the material of the rainwash from the surface-soil above 
the cave occurring also in layers in the cave; and if the cave 
happens to be occupied by wild animals when not flooded, we 
find their bones and the remains of their food scattered over the 
floor or buried in the rainwash. 
But when the turbid water fills a pool in the cave or a pond 
outside it, and the mud is allowed to settle down quietly, the 
coarser falls first and the finest last. Then the water evaporates 
or soaks through the sides, or remains clear and tranquil till the 
next rain carries in a flood of muddy water. The deposit so 
formed will have a tendency to split along the layers of coarser 
sand or loam which first settled down after flood—that is, it 
would be a laminated clay. As long as the pool was about the 
same depth, and the amount of mud carried in suspension in 
the water was the same, the thickness of the laminz would be 
practically the same, representing just the mud in one pondful 
of turbid water, whatever the interval between the refilling of 
the pond might be. The turbid water may come from the 
bottom of a glacier, or from melting snow, or from a heavy 
rainfall; but it certainly has no necessary connection with 
glacial action. We see laminated clay so formed commonly in 
the corner of any old quarry, in ditches, or in caves. 
In Chapel le Dale, a valley on the west side of Ingleborough, 
there is a beautiful chasm which has been so opened out by the 
action of the torrent, that you can get down to the bottom, 
where the water plunges on to a bed of broken rock and 
pebbles, through which it passes, as through a sieve or very 
coarse filter, into the water-courses that carry it off down Chapel 
le Dale. This great chasm is probably a fair representative of 
all the large swallow-holes. Hull Pot and Hunt Pot, on the 
flanks of Whernside, are of the same kind. Probably, there is 
in Gaping Gill, somewhere, a place where the water in ordinary 
weather filters through coarse gravel, for I have sent down many 
boards with a notice on each that I would reward any person 
who brought it back to me, but I have never heard of one of 
my notices being found. Yet, at times great boulders do get 
through, so it may be that the paint of my notices was destroyed 
in the subterranean waterfalls and rapids. 
These chasms or funnel-shaped holes are the feeders of the 
caves. They are only vertical caves formed in the horizontal 
surface of the rock. They are known as swallow-holes, Pot- 
holes, Sink-holes, and in Italy as Dolinas. They have various 
D 
