페이지 이미지

character of the formation in which they were found proved clearly that they must have been deposited there ages before the period usually assigned for the creation of man. The application which Professor Wilson had made of that fact was a very important one, for if ethnologists had so much longer a period in which to carry on their researches, they might find means to account for the great changes that have taken place in some portions of the human family.

The Antiquity of Man. By Profes3or Phillips (C.)—He said that one of the remarkable fruits of Geological investigation was to invest almost every point on the earth's surface with a new interest. The small French village of St. Acheul had long been remarkable for the school of the Jesuits established there; but antiquaries had discovered that it was near a burial ground of great antiquity. In the course of excavation there]were discovered the graves of people far more ancient than any known to have been buried there. Other memorials were also discovered; and on one he had obtained from the workmen he read the name of Constantius. A stone coffin was found, and also an armlet, which had been placed on the arm of a buried person. When they looked in front of the great face of excavation, and saw overhead the Jesuit College, the ancient cemetery, and the Roman and Pre-Roman graves, the question arose, " What could be the antiquity of the sand and gravel deposit at the lower level?" In Sir Charles Lyell's recently published volume the situation was fully described. Concerning the deposits, there was no difference of opinion; they were to be reckoned among the later deposits of the geological time, and in the lower parts of these deposits a great number of interesting implements had been obtained, and some of these he exhibited. He described the deposits in detail, from illustrations, stating that fresh water and land shells were found in sand and scattered flints in an argillaceous deposit over it. For the fresh water and land shells in the gravel it was not necessary to appeal to the action of the seas, which, however, was seen in the lower part of the level. There were, in different levels, cases of great agitation of water, comparative agitation, and comparative tranquillity. They might imagine a lacustrine deposit, against which there would be the objection that it would not produce gravel in such a form, it being twisted about in all ways. There ought to have been found lying parallel to the surface of the lake a great number of lacustrine shells; but that was not the case, and the explanation would not apply to the mixture of fresh water and land and amphibious shells. The more ordinary explanation was to suppose the action of a river which had changed its position, so that the flint

instruments found near the bottom might formerly have existed near the top. The arrangement of the sands was obviously of such a kind that they floated over the pebbles, and covered all below. The whole question came finally to this:—Could they determine the age of the gravel beds? They could not escape the conviction that the flint instruments were of the same age as the gravel beds. Upon the supposition of strata having been deposited by river action, the upper surface of the deposits would continually tend to become level, and would be so when the deposits were of an argillaceous nature. In this case the slope varied from 2\ to 1J degrees. In order to account for the present condition of things, it would be necessary to suppose that the country had been disturbed, and that there had been an elevation affecting the valley of the Somme. On an examination of the locality they would speedily arrive at the impression that it was requisite to remember that there was no period of geological history from which it was safe to exclude a movement of the earth's crust. The map of France showed the causes of the elevation. The rivers ran in parallel lines across the chalk, and it was impossible to separate the circumstance from the similar fact in this country, where these phenomena had been discovered. As there was reason to think that the valley had been subject to upheaval, accepting the supposition, they would not be able to determine the question of age by the excavation of the river. If they followed the suggestion of Sir C. Lyell, and took their measure from Scandinavia, they might come to some determination as to time; but this was a case of a local disturbance of the earth's crust, affecting certain lines of country in a given direction, and apparently ceasing beyond that. As it would be to some purpose to ascertain the antiquity of these deposits, he trusted Sir C. Lyell would not think it otherwise than a compliment to hear an opinion differing from his own.

Mr. Warington Smyth said that it was only during the last few years that this series had engaged attention In the main facts, as they might be taken by the public, geologists were pretty well agreed; but, nevertheless, the results to be deduced were so momentous in regard to the history of man, that they must be obliged to gentlemen who devoted not only days, but even years, to the elaboration of the details. Professor Phillips differed in no great degree as to his facts from Sir C. Lyell; but as to the explanation of thesephenomena and the physical agencies by which they had been produced there were differences of opinion, some attributing the present position of these curious strata to the erosive action of water, and some to elevations which we knew from other sources the whole of these countries had been subjected to within a recent period.

On the Alluvial Accumulation in the Valley of the Sommi and Oute. By Mr. R. A. C. Godwin-austen, F.R.S.—The object of this paper was to show that these two river valleys belonged to areas over which the geological changes had differed so greatly that, at present, comparisons could not be made; that the materials of the gravel-beds of the Ouse had, like those of all the rivers of the east of England, been derived from the "boulder formation;" and that the state of the animal remains indicated that they belonged to the fauna of the period antecedent to the boulder clay; consequently that, should it be proved that flint implements were to be met with in the Bedford gravel-beds, it would not prove that the Elephas primigeniiu and its associates were contemporaneous with man. The valley of the Somme was shown to belong to an area which lay beyond the "boulder formation"—that the series of alluvial beds differed greatly in respect of the physical conditions under which they had originated, yet that they indicated a definite order of succession, and implied a vast lapse of past time; in each of these flint implements have been said to have been found. The only evidence on this point which the author considers to be reliable is that with respect to the Champ de Mars, near Abbeville, where the beds belonged to the most recent portion of the alluvial series of the Somme, in the " subaerial" accumulations. The author further attempted to show that there is no sufficient evidence of a post-glacial elephantine period; and also that the Somme valley could never have been the line of drainage of a vast river, but that the phenomena of river alluvia at great elevations are to be accounted for by physical changes of definite date.

Sir C. Lyell said he had expected to hear Professor Phillips and Mr. Godwin-Austen express a wider divergence from his own conclusions than they had done. He took it for granted that Professor Phillips agreed with him in the important point that not only the flint implements which he mentioned in the case of St. Acheul were of the same age as the old river gravel, but also the extinct mammalia. It therefore appeared that they agreed in the important point of the coexistence of man with those extinct animals. The new view which he had attempted to explain was that the upper valley gravel, some eighty or one hundred feet above the level of the sea, was not now in the position it was when the river flowed there, and formed this extensive deposit of sand and gravel. If he understood the argument, there was such a slope of the gravel covered with loam towards the Somme as there would not be if it was the deposit of a considerable river in its original state; in that case the slope would be the other way, from the river towards the bluffs, as in the case of the Rhine and the Mississippi. He was not prepared to say whether it was possible to calculate on the identity of the present stale of that surface with what it was at the very remote period when it was formed, and since which it must have had so many washes by rain during many thousand years. He was not prepared to say whether they could reason in that manner as a change of position. What he said was, that there was nothing in his speculations on the river gravels hostile to the conclusions which Professor Phillips had proposed of there having been possible local movements, or, at any rate, a considerable movement of that country since the old river flowed. He thought it was almost impossible that that should not be the case. Indeed, when he found two levels of river gravel, one higher and the other lower, it generally appeared to him that that must be in consequence of some great movement, that there must have been probably some stationary period, when great accumulations took place; and that there must have been a period of movement, the waters eroding and cutting away the country, until they settled down at a lower level, and there was a formation of gravel there. This was a most propable thing; but they must bear in mind that though they talked of these appearances at two different levels, there were occasionally intermediate levels and deposits of gravel even higher than St. Acheul. It would be difficult to suppose that it was always strictly at two levels that these gravel beds occurred; but there was a prevalence of them at a higher level and at a lower level, that lower level being necessarily higher than that of the present Somme. He, therefore, had no objection to suppose that, after the country had been for some time in that state at which the gravels and sand were formed, there was some movement or elevation during which the river was able to cut the land down, and then form the inferior or lower level gravels; and it did not appear to him that if that view were adopted it made any very essential difference. Professor Phillips thought it made this difference—that the time would be much shorter if there were such a movement, and certainly it would; but he could hardly conceive any movement would enable the river to destroy so much older strata, as it must have destroyed to produce such reiterated river beds. If Professor Phillips could bring evidence of such a movement it would be a great assistance; but that would not alter at all any views which Mr. Prestwich and himself had arrived at with regard to the manner in which the higher and the lower levels were formed. There were other proofs besides the fresh-water shells, and the absence of marine animals, of the fluviatile origin of the St. Acheul gravels. The gravel in the Somme, the Seine, and their tributaries was composed of rock that belonged to the hydrographical beds of those rivers. In addition, there was the presence of fluviatile shells as well as of land animals. He could receive the views of Mr. Prestwich that these gravels were remains of an old river; and ho could admit that there might have been such a movement as Professor Phillips had supposed. Mr. Austen, in speaking of the Bedford section, had endeavoured to do away with the argument in favour of the antiquity of man, by supposing that the remains of extinct lions, rhinoceroses, and other animals, taken out of the gravel, which was about thirty feet above the level of the sea, were derived from an older gravek He supposed some preexisting formation, out of which the bones were taken, and then deposited in the present, so that that formation which contained the flint instruments would not be proof of the co-existence of man with those extinct mammalia, and that the mammalia existed before, and were washed out into the beds containing the flint instruments. Such an objection might be made to almost every river bed, because rivers were constantly ploughing np their channels, doing and undoing. Therefore, if any animal remains had sunk in the channel, the chances were that they would be torn out again, and rolled on before they got to their final resting place. It was perfectly true that in some of our valleys, such as the Severn, the old drift containing distinct animals will be undermined, and occasionally bones in a state of integrity will be thrown down into the new river bed. There were such cases, and they were guarded with respect to them; but as a general rule, if they found remains buried in gravel, the inference was they were formed during that long period when that ancient growth was deposited, bed after bed, and sometimes partly destroyed and re-deposited. If a geologist wished to draw a contrary conclusion, he was bound to show, first of all, where was the old formations out of which these extinct bones were derived. To make out his theory he would be bound to show that such a formation was under the drift of that country; which, however, was not the case. Under the circumstances, the hypothesis seemed a violent one, formed to get rid of a violent conclusion, to suppose that these bones had been derived from some other formation that existed in the neighbourhood, without a shadow of evidence of there having been such a one, and with all the existing evidence against it. He hoped the conclusion was one which, on reconsideration, Mr. Austen would not continue to maintain.

The Rev. S. W. King gave an interesting description of a section of the Norwich crag exposed by a recent fall of rock, and said he thought the name of the rock was too local.

Dr. Falconer could not accept the views of Mr. Godwin-Austen as to the mammalian remains in the implement-bearing gravels having been derived, like the inorganic materials, from a pre-existing age. No two mammalian faunas could be more unlike than those of the preand post-glacial ages. The Miocene Tertiary was marked by an exuberance of pachydermatous animals, and an excessively small development of ruminantia. Then, after a lapse of time so great that 1700 feet of strata had been formed in Europe, the Miocene mastodon dies out, giving place to two elephants and some colossal forms of deer; but still there was a marked absence of bovine animals. Immediately after the glacial submergence, new conditions of the surface set in, river-terraces and valley-gravels were accumulated from the pre-glacial material, but the organic contents of these were not those of the older beaches. All their characteristic types were wanting; instead of Rhinoceros Etruscus, Elephas meridionalis, and the larger deer, we had Bos priscus and primigenius, the musk ox, and the reindeer, and these bones often in a perfectly fresh condition— not rubbed, and scratched, and polished by ice-friction, as were the relics of the older time. So fresh and complete wore these mam

« 이전계속 »