122 KEY. G. C. H. POLLEN ON THE [Feb. 1 898, 



2. Sand. This is usually red from the presence of some clay, 

 but occasionally yellow and nearly pure. It has no lines of strati- 

 fication. 



3. Gravel. This is for the most part clayey, and contains the 

 following material : — 



(rt) Denbighshire Grit and micaceous shale — the ordinary stone 

 of the gravel — dark olive-green or greenish-blue to pale 

 greenish-yellow. When long exposed to wet it is very 

 soft, with an outer coating of dark shining clay. Size : 

 large grains to the size of a brick. The larger stones are 

 much flattened, like those of Glacial Drift, but there are 

 no striae visible on the stones in the caves. 



(b) Chert — frequent in the uppermost and lowest beds of gravel, 

 rarer in the middle — white or pale yellowish grey, often 

 containing Carboniferous chert-fossils ; subangular; without 

 striae. Size : small grains to fragments 2 inches in diameter. 



When we sent the first subangular specimens to Dr. Hicks, 

 he was inclined to think that they might be very rude 

 implements. But on subsequent examination of larger 

 quantities it was considered that they were too doubtful 

 to bring forward as evidence of man's handiwork. 



(c) Vein-quartz. Abundant in some places and scarce in 

 others, but confined to no special beds — white or pale 

 yellow, with black irregular markings ; much rounded ; 

 without striae. Size ; small grains to fragments 2| inches 

 in diameter. 



(d) Stalactites — only in large chambers — usually broken ; of 

 very coarse, crystalline structure ; up to 6 inches in 

 diameter. 



(e) Stalagmite — confined to the upper beds — coarsely crystal- 

 line ; ^ to 1 inch thick, small fragments up to 5 inches 

 square. 



(/) Limestone — masses of every size occur in all the beds 

 except the lowest gravel. In one part filling a swallow- 

 hole, the material was chiefly angular limestone in sandy 

 clay, with a few small grains of Denbighshire Grit and 

 small patches of purple clay. 



The top gravel in both caves is more sandy and contains stalag- 

 mite-fragments. The intermediate beds are often so largely mixed 

 with red clay that the bed might ratlier be called gravelly clay 

 than clayey gravel. The lowest bed contains most of the larger 

 stones of Denbighshire Grit in irregular patches, but is otherwise 

 very compact and fine. 



None of the gravels show lines of stratification, the stones, where 

 large or flat, being arranged according to the turns and eddies of 

 the water in a confined space, rather than in any consistent layers. 



4. The Brown laminated clay is in very fine layers of 

 various colours, some being red, others yellow or black, the general 

 mass being yellow when dry, and reddish-brown when wet. In 



