once obtained, probably in the manner just described, the ordinary flint knife would be sufficient for all subsequent operations, such as cutting and scraping the tools into shape.

It has been suggested above that perhaps the Adullamites of old possessed a knowledge of fire. This may have aided them in shaping and hardening sticks to be used in bonesplitting. This suggestion is by no means gratuitous, for it has been already stated that bits of charred wood and pieces of burnt bone have been frequently found in the Cavern, in the same deposit, and at as low a level as that which has yielded the flint tools and "Split Bones."

It may be stated in conclusion that the point we have reached is this:

1st. Those who are most familiar with them, are unanimous in asserting that the great existing Carnivores have never been known to split bones, and that it is believed they are incapable of doing so.

2nd. When plentifully supplied with suitable bones during an entire week, the most powerful hyæna in the Zoological Gardens, London, fractured them all obliquely and utterly failed to split one of them.

3rd. There is reason to believe that the bones were not split through exposure to meteorological agency.

4th. Palæolithic men were perfectly competent to split bones, and they would have a motive for doing so in their desire to obtain material for manufacturing the bone tools which they are known to have used.

THE SUBMERGED FOREST AND THE PEBBLE

RIDGE OF BARNSTAPLE BAY.

BY W. PENGELLY, F.R.S., F.G.S., ETC.

ON the southern shore of Barnstaple Bay in North Devon, immediately south of the joint estuary of the rivers Taw and Torridge, there is an extensive, sandy, grassy plain, known as Northam Burrows. A considerable portion of it, at least, is but little, if at all above the level of spring-tide high-water, so that it would be exposed to destructive inundations and encroachments during heavy gales, were it not protected by a natural breakwater composed of pebbles of the Carboniferous grit of the district, and known as the "Pebble Ridge." The pebbles or boulders vary from half an inch to a yard in mean diameter, the majority being about nine inches. The greater number of them are oblate spheroids, but occasionally prolate and nondescript forms present themselves.

Seaward from this ridge, the tidal strand at first consists of small pebbles, of which the great majority are also of grit, whilst a few are of flint. Beyond this, to the low water line, it is composed of fine sand, beneath and frequently projecting through which are large accumulations of tenacious blue clay and vegetable matter, containing roots, trunks, and branches of trees. The vegetable remains are known as "The Submerged Forest of Barnstaple Bay." The clay is in some places six feet thick, and reposes on a bed composed of fragments of the grit of the district. According to one observer these fragments form an upper and a lower bed,—the former consisting of pebbles, the latter of angular masses.t Another writer states that the vegetable bed "rests invariably on a stratum of angular fragments." So far as my own limited observations have gone, the bed immediately beneath the clay consists sometimes of rounded and sometimes of Mr. Spence Bate in Trans. Devon. Assoc., 1866, p. 130. + Ibid.

Mr. Ellis in Op. Cit., p. 80.

angular fragments. Be this as it may, the constituents of this inferior bed, with the exception of the angular pieces only, resemble in all respects those of the Pebble Ridge.

Westward from the Ridge, the tidal strand is commonly a rocky platform, more or less loaded with pebbles in all respects like those forming the Ridge itself, and which, as may be expected, are most numerous at the foot of the cliff, from ten to fifteen feet high, by which the strand is bounded.

This cliff consists of yellowish clay, with angular stones derived from the hills immediately behind or on the south, and is the termination of a narrow plain, ten feet and upwards above the general level of the Burrows.

At a short distance further westward, this cliff gives place 'to one somewhat higher, and of great interest to the geologist. It is resolvable into three portions or stories :

1st or lowest. An old platform or terrace of denudation, terminating in an almost vertical cliff, from 15 to 20 feet above the level of the existing tidal strand, and formed on the shorn down outcrop of highly inclined beds of Carboniferous Grit. 2nd. On this shelf lie well-marked remnants of an old Raised Beach, about seven feet thick, frequently composed of pebbles differing in no respect from those lying on the strand beneath. The two beaches in fact, like the platforms on which they lie, differ only in one being high and ancient, the other low and modern.

3rd. Commonly, the old beach is capped with a sub-aerial accumulation or "Head" varying from 5 to 20 feet in thickness.

The Carboniferous rocks of the district are traversed by two distinct and well-defined systems of joints, which, with the planes of bedding, facilitate the resolution of the beds into rhombohedral blocks, which are rapidly converted by the waves into the spheroidal pebbles and boulders so abundant on the ancient as well as the existing tidal strand.

Though most, probably all, observers have found themselves under the necessity of admitting that the Submerged Forests are the remnants of trees and other plants which grew on the very area now occupied by the vegetable debris, and, thence, also that districts once sub-aerial have become tidal or submarine, expressions of doubt have been heard from time to time as to whether the forest phenomena are necessarily the results and proofs of a subsidence of the country.

To suppose that an area once occupied by terrestrial vegetation has been converted into one of a marine character

without undergoing any change of level, is to suppose that during the forestial period it was below the sea level, but was protected from inundation by some natural breakwater. There is no alternative. This hypothesis, or that of subsidence, must be accepted. Accordingly all those who object to, or are sceptical respecting, a change of level, accept the supposition of some kind of natural breakwater.

So far as I am aware, the latest recurrence of this opinion is that which, about two years since, was proposed in explanation of the phenomena of the Submerged Forest of Barnstaple Bay, and which is distinctly stated in the following passage from the paper alluded to:-"The origin of this pebble ridge has not, by geologists, been determined; but I think that the most correct opinion is that it is formed by the wash of the sea destroying the beds that overlie the pebble bed that exists beneath the clay. . . . I think that there can be little doubt, but that the terrible wash of the Atlantic thins off the clay, and so exposes the pebble bed below to the action of the sea, which, by degrees, carries pebble after pebble to add to the wall that separates the burrow from the beach. That the great pebble ridge is moving inwards is certain, but the rate of progress has not, I believe, been determined. The gradual movement inwards of the ridge, however fast or slow, exposes all the shore that is seaward of its protection to the destructive agency of the waves it is to this, and not to any variation of the level of the coast line, that I believe that the submergence of the forest along the shore is due. . . . . . The facts that the beach at the shore extremity is scarcely below the level of the burrows, while the strata of which it is composed gradually thin out as it approximates the low water line, demonstrates clearly, I think, that the submergence of the old forest bed is due to the removal of the beds, and encroachment of the sea, and not to the subsidence of the land."*

In the passage just quoted, the author is clearly of opinion that his hypothesis accounts not only for the submergence of the forest, but also for the origin of the pebble ridge. I purpose reviewing it in both these aspects.

And, first, with reference to the Submergence of the Forest. Why should it be thought incredible that it was due to subsidence? Manifestly such a cause would produce the effect, and so far as is known, would leave no outstanding phenomena. That the entire country around Barnstaple Bay has undergone Trans. Devon. Assoc., 1866, p. 134.

upheaval in times geographically recent, is established, beyond a question, by the fine Raised Beaches and Terraces of denudation which fringe its coasts. There can be no à priori difficulty, then, in supposing a movement in the opposite direction. Further, remnants of forests of precisely the same kind of plants as those in the peaty masses on Northam Strand-all of them such as now inhabit the adjacent dry lands -are found all round the British islands, and, indeed, on all the shores of the British seas. Their submergence is ascribed by geologists to be a wide-spread and uniform subsidence, and unless this ascription is well founded, it must be supposed that a series of natural breakwaters once extended round Britair, to say nothing of the other islands of the archipelago, or of the adjacent coasts of the Continent. Our island must have been begirt with a wall of circumvallation, and the forests must have grown in the fosse. This conclusion, to which the breakwater hypothesis legitimately leads, no one would entertain probably for one moment.

But let us confine ourselves to the Submerged Forest of Barnstaple Bay, and see whither we are led by this supposition of non-subsidence.

1st. The primary position of the Pebble Ridge must necessarily have been without, or seaward of, the forest; and as this at present extends to the line of spring-tide low-water, and there is no reason to suppose it terminates there, the inner margin of the Ridge must have occupied a line now permanently submarine, whilst its outer edge must have been much further seaward.

2nd. Since the waves occasionally bound over the crest of the existing ridge, the top of its earliest representative could not have been at a lower level.

3rd. As the vegetable mass is admitted to consist of remains of plants and trees occupying the very position, level, and soil in which they grew, as they extend quite to, at least, the line of the greatest retreat of the tides, as the tidal range in Barnstaple Bay amounts to 28 feet, and as the plain within the present ridge is at the level of spring-tide high-water, it follows that the height of the ridge above the plain it protected in its primal position must have been at least 28 feet greater than now.

4th. Assuming that its present contour is that best adapted to resist wave action, and that it is that which has always been maintained, the comparative dimensions of the hypothetical ridge when it stood at the low-water line may be easily calculated. It is obvious that the length of this bul