Page:Quarterly Journal of the Geological Society of London, vol. 33.djvu/711

Rh in the contents of any other cavern, which may be explained by these being nearer the surface of the ground above, and therefore more exposed to the attack of the acid-laden water than the great majority of caverns.

It may be added that the same results may be produced by chemical action intensified by pressure, as pointed out by Mr. Sorby's experiments.

It remains now to sum up the results of these explorations of the Creswell Caves. The associated species of the Robin-Hood Cave are the same as those of the Church Hole; and there can be no doubt that the caves were inhabited at the same time. The fauna of the Red Sand and of the Cave-earth is alike in both. The palæolithic hunter who first appeared used ruder implements than those who succeeded him.

The animals belong to groups which spread over Central Europe, from the Pyrenees as far north as the Elbe, and swung to and fro according to the season. They would naturally find their way from the low grazing-lands now occupied by the German Ocean up the line of the Trent to Creswell, as may be seen by the accompanying map (fig. 9).

In the absence of physical evidence it is useless to speculate on their relation in this district to the Glacial period, because they lived in Europe in Preglacial, Glacial ( = Interglacial), and Post-glacial times.

Nor, may it be added, is there satisfactory evidence offered by any cave in this country which enables us to fix the relation to the Glacial age of any cave-fauna in particular. In the Victoria Cave, for example, quoted by Mr. Tiddeman, Mr. James Geikie, and others, as decisive of the Pre- or Interglacial age of the cave-fauna below the clay, the whole question turns on the age of the clay above the bone-bearing strata at and within the entrance. And this is not proved to be "boulder-clay" ('Ice Age,' p. 510), because there are no boulders in it; nor is it proved to be Glacial ('Nature,' 1876, p. 505), because clay of that kind is now being deposited in that very cave. That it has ultimately been derived from the wreck of the Boulder-clay at a higher level, which was formerly spread over the country, and has been washed in by the rains, is very probable. Nor do the piles of travelled blocks which occur in the talus outside the entrance throw any light on the point, because they are remaniés and not in situ. They may have tumbled from the cliffs above during the accumulation of the talus, and long after the glaciers had retired from Yorkshire. These doubts as to the pre- or interglacial age of the fauna below the clay which grew up in my mind while intrusted with the conduct of the exploration, and have