to suppose that with, the valleys excavated to the present depth, any meteorological causes could fill them to their summits; or even if they could and did, that they would leave such deposits as we find at high elevations on their slopes, or even on detached eminences. It will, however, be well to examine briefly any corroborative evidence that may be forthcoming, as to the probability either of a severer climate involving a greater accumulation of winter snows, or of a greater rainfall, or of both. The one, indeed, seems hardly probable without the other, as a cold land surface "presented to vapour-laden sea-winds, as in the mountainous districts of the north-west of Spain, in our own lake districts, and in Scandinavia,"[1] involves of necessity a heavy rainfall.
With regard to climate, we may take into account that which prevailed at a somewhat earlier date; for there appears no doubt that the flint implement-bearing gravels are all of later date than the Chalky Boulder Clay of the Eastern Counties, a deposit which belongs to the so-called Glacial Period, during a portion of which a great part of England and Scotland was submerged beneath the sea, and became coated with masses of Boulder Clay and other deposits, derived for the most part from the moraines of glaciers, sometimes at no great distance, and possibly in the main transported and dropped in their present positions by means of icebergs and coast ice. That they are of later date is proved by more than one of the implement-bearing beds reposing in valleys either in, or cut through, this Chalky Boulder Clay; and at Hoxne the interval between the Glacial deposits and the Palæolithic beds is marked by two sets of lacustrine strata, the lower and earlier with a flora characteristic of a mild climate, and the upper by one which points to the recurrence of Arctic conditions. Prof. Boyd Dawkins[2] has suggested the probability of the higher ground of North Wales and the northern part of England having been still enveloped in an ice-mantle at the time that the mammoth, reindeer, and other post-glacial mammals were living in the lower and less inclement districts. But this view is to some extent founded on negative evidence, and on the assumption that palæolithic implements do not exist in this northern area. I have already commented[3] on the possibility of implements being eventually found in it.
The crumpling and contortion of some of the beds of River--
- ↑ Phil. Trans., 1864, p. 291.
- ↑ Q. J. G. S., vol. xxv. p. 209.
- ↑ p. 580 supra.
