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PKOE. T. H'KENNT HUGHES ON THE 



First, I will take Plas Heaton. This I explored with the late 

 Mr. John Heaton. The existence of the cave had been long known. 

 It was exposed in opening a quarry, and the broken rock and fallen 

 drift and rainwash round the mouth were by degrees removed. On 

 removing an old wall built across the mouth by earth stoppers we 

 could then get in a little way. The slope of the soil was inwards 

 at the end next the house, showing that the infilling of that part 

 was chiefly from the mouth behind the increasing barrier of rock- 

 debris and washed clay. It rose again towards the far end. A 

 large number of bones occurred in the first part, and the earth 

 was excavated and laid on the land. Among the bones were those 

 of Hysena, Dog, Wolf, Pox, Glutton, Bear, Badger, Reindeer, Sheep, 

 and Rabbit. 



The lower jaw of Glutton I picked up myself, as it was thrown 

 out by a workman who was digging in the cave. Not far from it 

 were pieces of a large bottle, like a magnum, buried in the earth 

 beyond where we could creep before the excavation had commenced. 

 These had probably been thrown in, and appeared to have got so 

 far, partly by being carried on by the rain, partly because this 

 part of the cave had rapidly been filled, and partly because the earth 

 had been disturbed by badgers and other burrowing beasts. We 

 found the skeletons of two badgers and two dogs all together in one 

 place as if two hounds had got into a badger-earth and all had 

 perished together. 



When this cave had been further excavated, bones became very 

 scarce, and the cave ended off in a great mass of red clay with 

 boulders, slipped masses and washed debris from the St. Asaph 

 clay-drift, which lies above. Had we come first upon this cave by 

 digging from the end still unexplored, some would have said it 

 was a preglacial cave, and that its mouth was sealed by Boulder- 

 clay. 



In the deepest part of the cave, in the hollow between the accu- 

 mulations drifted in from either entrance, there was a mass of very 

 fine chocolate- coloured clay, in places finely laminated. This was 

 evidently due to the settling down of the finer sediment washed in 

 through crevices when the cave was nearly choked. 



When great storms no longer flood a cave, but the rain still 

 causes a pond of muddy water here and there within it, we find 

 that laminated clay is formed. No stream or wind stirs the quiet 

 water in the deep recesses of the cave, nothing but a falling 

 drop breaks its smooth surface ; the mud settles down, first the 

 coarser, then the less coarse, and last the very finest. So as 

 there is a parting of coarser material between every layer of fine, 

 the result is a laminated clay, the thickness of each layer depending 

 partly on the depth and partly on the turbidity of the water which 

 filled the hollows. 



The lamination is caused by the alternations of wet and dry 

 weather ; but as long as the basin does not vary appreciably in 

 depth, and the amount of sediment in the water is the same, the 

 lamination must be approximately regular, whatever the intervals 



