176 CAVES AND CAVE DEPOSITS. 
only one end of the caves. In the case of the Plas Heaton 
cave, as in that of Cae Gwyn, one end of the cave was open ; 
so that there is no difficulty about the manner of occurrence of 
any of the objects except those in and under the drift at the 
upper entrance. In some of the caves in the Valley of the 
Elwy, the direction in which the principal part of the coarser 
material of which these cave deposits were made up had been 
carried was pretty clear, namely, from the drift covered end, by 
water getting in along porous beds and fissures. In later times 
the caves got nearly filled by ordinary cave deposits, the result 
of the decomposition of the limestone, and the clay and sand 
washed in through fissures In the Plas Heaton cave, the mass 
of drift overlying the north end of the cave does seem to be the 
Clwydian drift, or derived directly from it. But in the case of 
the Cae Gwyn cave I do not feel at all sure of this. The 
material that I saw in the section when we first broke out to-day 
from the inside of the cave, namely, that which had fallen into 
the cave through the swallow hole, did not appear to me to 
resemble any known section in the undisturbed Clwydian drift. 
It is quite unlike the great masses of red sand exposed here 
and there in the Wheeler valley. There is nothing in the 
section below the Mount, or at Bryn Elwy, at all resembling it. 
It is not like the drift of Wigfair-isaf, or the variable deposits 
of Wigfair-uchaf—except in each case the obvious top few feet 
of rainwash It is like the mixed mud and sand and gravel 
which we find everywhere overlying the Clwydian drift, crumb- 
ling down the hill side, and conforming to the slope of the 
ground. There is no sorting of the material as we should 
expect if currents ran along the rock face or waves dashed 
against it, but there is here and there an obscure and gentle 
falsebidding from the cliff as of rainwash creeping down the 
slope. To show the scratched stones from Arenig is to prove 
too much or too little. There can have been no man or hyznas 
there when the ice sheet from the Snowdonian and Arenig 
mountains carried moraine matter across the Vale of Clwyd. 
There are no scratched stones among the included rocks which 
are peculiar to the Clwydian drift, and if all the scratched stones 
are derivative, they must have been washed from the old 
Snowdonian drift into the Clwydian drift, or from that into the 
rainwash, and may be handed on still. Again, at Plas Heaton 
the northern end of the cave is buried in a mass of clay, which 
if it does not belong to the Clwydian drift must have slipped 
down bodily. There is no long slope of ground above it to 
cause any crumbling down of all the superficial deposits from 
above. At Ffynon Beuno, on the other hand, the superficial 
deposits are creeping down the hill sides, hanging on every 
ledge, and catching on every obstacle. Any old hedge proves 
how rapidly this process is going on. One such hedge ran 
across the bottom of the field in which the northern end of the 
cave comes out, passing up to the edge of the precipice about 
zo feet below where tne higher end of the cave comes out. 
There we see that the ‘‘head” or travelling talus has been 
