The British Association: Section C Geology

    Abstract

    A preliminary Account of the Working of Dowkerbottom Cam in Craven during August, 1881, by E. B. Poulton, M.A., F.G.S.—Dowkerbottom Cave is 1250 feet above the sea, between Arncliffe and Kilnsey. Its mouth is merely a fall in the roof of the cave, which stretches from either end of the fissure thus formed. The original mouth is not now visible, but is probably to be found at the foot of a slope to the south. During most of its course the chambers and passages of the cave are not separated by any great thickness of rock from the ground above, and thus other falls must be expected to occur. The eastern division of the cave is about 450 feet long, and has three fine chambers separated by two passages, the first very short, and the second very long. This division ends under high ground, and the true mouth must be in the other, or western cave. The last chamber is characterised by mechanical deposits—blocks of limestone fallen from the roof and a stiff brown clay beneath. In the other chambers and passages are chemical deposits—hard and soft stalagmite. The western division is smaller, but also contains three chambers and two passages. It must be about 250 feet long. Chemical deposits, with some falls from the roof, are present throughout. In former workings by Mr. Farrer, Mr. Denny, and Mr. Jackson, the first chambers were explored in their surface layers at least, and here were found the numerous metal and bone ornaments and implements, together with the bones of animals usually found in the historic layers (of Romano-British age) in caves. The second passages have also been worked, and part of the second chamber on the eastern side. Other parts of the cave appear to be quite untouched. The great difficulty in working the cave is the removal of the débris to prevent its interfering with further work. We therefore put up a windlass over the eastern entrance and cleared a way for barrows through the talus below. Beneath the talus the black earth, in which remains had been previously found, was seen, and many articles of Roman age were taken from it. Chamber III. was marked into parallels, and these into squares. In the centre we sank a shaft and passed through the following layers:—(1) Romano-British layer, a black earth with pottery, ornaments, & c., and numerous bones, usually from I to 2 inches thick; (2) hardish stalagmite, about 6 inches thick, in one place containing the bones of a dog or small wolf; (3) soft stalagmite 4 inches thick; (4) hardish stalagmite 6 inches thick; (5) soft stalagmites, feet 6 inches thick; (6) stiff brown clay with large angular blocks of limestone fallen from the roof firmly imbedded in it. This layer was 8 feet deep, as far as we saw it. The last two feet are laminated and contain smaller blocks. At the depth of about 12 feet from the surface we came upon part of the solid limestone floor or side of the cave, sloping steeply downwards. There were no indications of a change in the nature of the deposit at the junction with the limestone, and the clay appears to extend much deeper than the level at present reached. Thus below the stalagmite purely mechanical deposits succeed, and no limestone blocks are found above this horizon, although the stalagmite has been removed over a large part of the floor of the chamber. No traces of a fauna have been as yet found below the first hardish stalagmite; indeed all the deposits passed through below the stalagmite indicate the former presence of a still lake in which the great thickness of clay slowly accumulated. Further work was stopped by the heavy rain which flooded the shaft dug in the clay. It is interesting to note that the former condition of Chamber II. is identical with the present state of the third chamber in the preponderance of mechanical over chemical deposits. The change from mechanical to chemical deposits was probably produced by a change from accumulation in still water to accumulation in running water. Possibly also the absence of blocks fallen from the roof in the stalagmite may be due to the bicarbonate of lime contained in the water which percolated through the roof, cementing together the limestone blocks. The absence of this cement when the clay was deposited may be due to the absence of solvent power in the water which then percolated through the roof. For the carbon dioxide would not be evolved from a soil deficient in organic matter, as the soil covering the Yorkshire hills for a period long after the Glacial period must have been. The author expresses his best thanks to Mr. J. R. Tennant of Kildwick Hall, Leeds, and to Mr. J. R. Eddy of Carleton, Skipton, who gave, on behalf of the Duke of Devonshire, the permission to work the cave, and further aided with kind help and advice all through the work.

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    The British Association: Section C Geology. Nature 24, 494–498 (1881). https://doi.org/10.1038/024494a0

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