ON THE EXPLORATION OF THE SETTLE CAVES. 137 
attend; Mr. John Birkbeck, Jun., represented the Settle Committee: we had 
the valuable assistance of Messrs. Aveline, Dakyns, and other gentlemen. 
We were unfortunately deprived at the last moment of the valuable services 
of Professor Ramsay, who had expressed his intention of being present, but 
was prevented by public business. 
In the course of the 6th and 7th of July the boulders were quickly brought 
to view and in great numbers; we counted over two hundred, of dimensions 
from a few inches to 6 feet in diameter, besides numberless smaller ones 
which it was not possible to preserve. Wherever a boulder was exposed it 
was left in situ, and the clearing away of the talus proceeded along the face 
of the bed, In several places we found a little clay above the boulders; but 
it was apparently of very recent introduction, and had been washed into the 
talus by the draining of water from above before the workings had got down 
to their present leyel. This was apparent from its containing blades of grass 
and pieces of straw which had not rotted away. 
The boulders were found to be lying in an irregular layer from 3 to 4 feet 
thick at bottom, dipping outwards from the cave in a direction W. 40° S., 
and extending across its mouth at the level where we were then working ; 
but at the north-western extremity of its range it curved round more to the 
north, and therefore dipped more westerly, showing in all a breadth of glacial 
deposits of about 12 yards. The boulders consisted almost exclusively of 
blocks of Silurian grit and of Carboniferous Limestone in about equal num- 
bers, but there were one or two of Carboniferous Sandstone. The form was 
quite enough to distinguish the Carboniferous Limestone boulders from the 
sharply angular blocks of the talus; but, besides, many of them were of black 
bituminous limestone, and not of the white limestone in which the cavern is 
excavated. They were nearly all of well-marked glacial form, and most re- 
tained glacial markings. One round pebble of limestone was found near the 
base of the bed. The sites, dimensions, and arrangement of-some of the 
principal were noted with reference to a level datum-line running N. 40° W. 
from a mark upon the wall of rock on the right, and after the section had 
been well cleared of talus ; the boulders were marked (S) for Silurian and (L) 
for limestone, and then photographed. Angular pieces of limestone, similar 
to those in the lower caye-earth and in the talus, were mixed up with 
boulders throughout, and the whole was filled in with mud, but much of it 
appeared to be rather recent. The boulder-bed thinned away upwards, and 
is apparently thickening rapidly towards the dip ; doubtless it will be found 
much thicker at a lower level. 
In accordance with a suggestion from Professor Prestwich, a hole was dug 
in front of the large fallen block which forms the arch already mentioned, 
and the boulder-bed penetrated. A great many large and small boulders 
were dug out of this hole. Beneath was a bed of angular grayel filled in 
with clay a few inches thick. When washed, the small pieces of stone of 
which it was composed were found to be really small boulders, many of 
them scratched and bruised. Whilst wet it bore some resemblance to the 
gravel which covers little cones of ice low down upon a glacier near the 
moraine, and which offers such appartntly good, but really bad foothold to 
unwary travellers*. Below this were a few inches of yellow. clay, which 
Mr. Jackson, our Superintendent, says is similar to that which was found at 
the bottom of the 12 feet of laminated clay in the 25-foot shaft in Chamber B. 
This is an interesting point; for if the laminated clay and the boulder-bed 
are both of glacial age, it seems likely that this thin bed of yellow clay 
* Forbes, ‘Theory of Glaciers,’ p. 241, 
