This proposition, however, seems to me fallacious; the question is not as to the actual but as to the relative heights of the water-sheds and the hills in question. Subaerial denudation would affect both alike. If the loftiest eminences suffered, the lower would not be spared, and thus, if no present river could possibly have formed these deposits, we must believe, assuming the relative contours of the surface to have remained the same, that such submergence was from the first equally impossible.

Further, if we should be satisfied, as it seems most probable, that the Drift implement gravels were deposited before England was severed from the continent, and while, as has been supposed, England extended much farther to the east, and the Thames, or what is now the Thames, was probably an affluent of the Rhine, it becomes in the highest degree improbable that the present rivers Somme and Ouse should, so to speak, have survived these great changes, and continued still to occupy their ancient channels and courses.

But, if it is thus improbable that the gravels were transported by existing rivers, it seems still more improbable that the transport of the implements found in them should be ascribed to that cause. For reasons already stated, and for some others which it would occupy too much time to give in detail, I incline strongly to the belief, that they were for the most part manufactured by men resorting to the beds which were then exposed upon the surface, and were left where we now find them, and afterwards covered up, possibly by the same changes, whatever they were, which drove away the occupants of the soil, or, it may have been, destroyed them.

And here I may notice, that those authors who have insisted that these gravels were transported by river agency, have mainly relied upon the assumption that the valleys contain no other rocks than such as are found in the upward courses of the rivers, and which, in their descent, have followed the course of those valleys.* The case of Brandon, however, seems conclusive against such an assumption. Here the implements occur under compact masses of chalk flint, mixed with pebbles of quartzite, white quartz, jasper or Lydian stone, and other rocks, composing what is known as Glacial Drift, of which considerable deposits are also found at Finchley, and at Muswell Hill, and elsewhere to the north of London, and which has been fully described by the late Dr. Buckland. At Brandon these quartzite pebbles occasionally form a layer more than a foot in thickness, and in some spots make up one-half of the whole mass of gravel. Professor

* Sir John Lubbock, "Prehistoric Times", 2nd edit., p. 358.

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+ Geological Society's Transactions, 1st series, vol. v. p. 516. Reliquiæ Diluviana", p. 249.

VOL. I.

U

Ramsay has shown that they are derived from a Permian conglomerate of the New Red Sandstone of Shropshire and Warwickshire, which, at the nearest point, is two hundred miles west of Brandon. But, whatever their origin, it is certain that neither to the east of Brandon, nor, indeed, elsewhere in the county, is there, or ever was, any formation from which these gravels could have been derived; and, as the river here runs east to west, it is impossible that it should have carried them. Indeed, in the present configuration of the land, no river flowing from the west could have deposited this gravel, inasmuch as, before reaching this eminence, it must have been intercepted and lost in the estuary which is now represented by the great level of the fens. So late as the Anglo-Saxon period, this district was an archipelago, as is shown by the names of the towns and villages-as Manea, Stonea, Whittlesea, Hilgay, etc.—indicating islands and what are now rivers flowing into it, were then, as now, known as creeks.

Before leaving this part of the subject, I must notice some phenomena which seem to be in conflict with the views here stated. In some few instances, land and fresh water shells are found in or near to the implement bearing gravel. At Salisbury, St. Acheul, and Menchecourt, they lie above the gravel; at Bedford in it; while at Brandon, Bethune, and many other places, no trace whatever is found of them. In no case, however, I believe, are they found lying undisturbedly beneath gravels which contain flint implements. This circumstance certainly suggests the belief, that the gravels, and the implements with them, may have been carried down by river action; but, even in that case, not necessarily by rivers draining the same areas, and following the same courses as now. On the other hand, it is certain that the implements could not have been made under water: and, from their occurrence in such great quantities, and that in those spots where the stone is well adapted for making them, their presence can hardly be regarded as accidental; while, from the perfect condition of many of them, it is certain that they cannot have been carried far, if at all. The occasional occurrence of shells above them may perhaps be accounted for, by supposing, that, in the long interval that has undoubtedly passed, pools or streams of fresh water may have been formed above the gravel; and that, as regards Bedford, the original deposit may have been broken up and rearranged by the invasion of a river, bearing the shells which are now found with the implements; and this seems the more likely, because that bed alone, of all the English or French true. Drift beds, contains remains of reindeer and elk, mingled with those of animals now only met with in warm climates.

Quarterly Journal of Geological Society”, vol. xi, p. 185.

It cannot be doubted that occasionally flint implements have been found lying above the lowest beds of gravel; a circumstance which may, perhaps, be explained upon the hypothesis, that they have been displaced and carried down by floods from their original position. I confess, however, that the occasional, but rare, occurrence of implements in the loess can hardly be thus accounted for; nor, indeed, can it easily be accounted for in any way, since the loess is the deposit of earth held in suspension in muddy waters. But, however this may have been, the material fact still remains, that the implements usually occur in the very lowest gravel stratum, and sometimes even on the surface of the older rock, and that this bed appears to be separated both geologically and palæontologically from the surface, as well as from the caves which are upon the surface, by an interval of such duration that it seems hardly credible that the human race should have lived through it, and left no other traces of their presence than these rude implements.

Upon the whole, the argument as to fluviatile agency may be thus stated. If the contours of the surface were the same, or relatively the same, as at present, then the existing rivers could not have carried these gravels to the places they now occupy. If, however, the contours were not the same, or relatively the same, as now, then the rivers which carried them-if indeed they were carried by rivers--did not flow in the same course, or drain the same areas as they now do, and all traces of them have now been effaced; or, if we exclude fluviatile agency altogether, nothing is left but to adopt the views held by the French geologists, as well as by Dr. Buckland and Mr. Greenough, that these superficial drifts are attributable to some kind of sudden but violent deluge, either fresh-water or marine, of short duration; and this seems the more probable, when we find that the compact beds of gravel, often fifteen or twenty feet in thickness, which overlie extensive districts in the south-east of England, are entirely destitute both of marine and fresh-water shells.

I am aware that this opinion is not now held by English geologists generally, but perhaps it has been rejected with hardly sufficient consideration. Sir Roderick Murchison, in a paper on "The Flint Drift of the South-east of England", read before the Geological Society in May 1851, expressed his belief that the mammalian flint and chalk detritus was accumulated tumultuously, and could not be attributed to the ordinary long continued action of water; and Mr. Prestwich, in his paper on "The Sangatte Drift" (a somewhat similar deposit), stated his opinion that the action which led to its accumulation was "sudden, powerful, tumultuous, not of long continuance, and suddenly arrested". These terms, which exactly describe diluvial as distinguished