Page:Popular Science Monthly Volume 12.djvu/75

Rh ; and, in the south, Mr. Godwin Austen, from a study of the same remains in the valley-gravels. Direct evidence of great value has been added by Mr. Tiddiman in his reports on the exploration of the Victoria Cave, at Settle. He has shown that the cave-deposits lie beneath glacial clay, and, among the other remains, a human fibula has been found. In the Cefn Cave, in Denbighshire, Mr. Mackintosh has also determined that the mammalian remains lie in and below a glacial clay.

All the lines of inquiry thus far pursued in this paper point to the preglacial age of the remains in question, and some of the facts are directly opposed to the post-glacial theory. How, then, is it that the great majority of geologists write as if it had been clearly proved that palæolithic man was of post-glacial age? Principally because it is believed that Prof. Prestwich has proved that at Hoxne, in Suffolk, the implements and bones are found in deposits distinctly overlying bowlder-clay. This is spoken of as if it were a truism in most general treatises on geology; and both in Europe and America the presumption is appealed to as being conclusive with regard to the age of the remains. The general opinion held is concisely given in the statement by Mr. John Evans in his presidential address to the Geological Society last year, that, at Hoxne, "the implement-bearing beds repose in a trough cut out in the upper glacial bowlder-clay, which itself rests on middle glacial sands and gravels."

This opinion of the age of the Hoxne deposits is founded on the elaborate memoir by Prof. Prestwich, published in the "Philosophical Transactions of the Royal Society," for 1860. In this treatise the author gives a diagram showing the deposits in question lying in a trough cut out in the bowlder-clay. Though this section is confessedly only theoretical, it was accepted by Sir Charles Lyell and others as an actual one, and afterward the author himself wrote as if he had proved his theory to be true, which he may well be excused for having done, when it had been accepted by so many eminent geologists.

The writings of Prof. Prestwich are admirable in this, as in other respects, that, although he indulges in wide-reaching theories, he invariably gives the evidence on which they are founded. Thus, in the memoir in question, in addition to the theoretical diagram he gives another, showing the actual facts observed, and also careful details of the various sections observed by him. It is, therefore, possible to check his theory by his facts, and in the present paper I shall do so,