Page images



first wheel and the discoverer of fire. These examples pre- the lack of scientific spirit is felt in other directions. The pared ihe way for a consideration of the conditions, other cause of this deficiency is in no sense due to a want of than those of the researches of the laboratory, to which national ability. Prof. Lippmann put it down to an antiindustrial work is subject. The burden of the president's quated system of public education. French education, he remarks was that nothing is too insignificant for careful assured his audience, is Chinese in origin as well as in attention, and that qualified workmen require long character. tining

The president in directing attention to higher education well-instructed technical staff is indispensable to every in France saw in this direction cause for hope and the works; the men may be prepared in special schools, but remedy for the shortcomings he had previously enumerated. their work must be learnt in the shop itself, for it can In countries where the conditions of culture are normal, be learnt properly nowhere else. It is equally important every young man to whom it is desired to give a liberal that the managers of the factory be properly trained and education is sent to a university, not for reasons of vanity, be provided with research laboratories where trials should but because it is necessary for the youth's professionaf be made with an automatic regularity.

future. This necessity is not, Prof. Lippmann maintained, But even when all these things have been provided there sufficiently understood in France. The young man should should be no standing still. In industry, said Prof. Lipp- go to the university not only to learn law or medicine, but imann, one is never tranquil. When everything has been in order to become a cultured man. provided for, there is still the unforeseen, and the rivalry The chief business of the university is to teach the art of other producers at home and abroad has always to be of research, that is to say, science, for science is the art reckoned with. " Industry is a struggle without end and of research and nothing else; and research is indiswithout truce."

pensable to industry. At the same time, the university The president then went on to show how, as science made must put men with no scientific ambitions, but who wish new discoveries, technical experience became insufficient, to acquire a general culture worthy of the name, in touch and without scientific assistance an industry inust fall be- with science at first hand, for science in the making is hind. He insisted upon the value of mathematics, and alone attractive and fruitful. The French universities are maplained that all the resources of mathematical analysis at present too much under the influence of a bureaucratic can be brought into requisition in industrial undertakings, pedantry to accomplish this double function, and the sooner instancing the way in which Lord Kelvin found by analysis they are liberated from the voke of the executive power the the cause of the remarkable slowness with which electric better according to the president. So far as unfettered signals traversed the Transatlantic cable at the time it was universities are concerned, France is, in Prof. Lippmann's being laid. He then gave other instances of how men of view, behind the rest of the world except Spain. science have provided new resources to the industrial ex- Prof. Lippmann concluded by expressing the devout hope, pert, and concluded by again urging the need at every in the name of industry and of national development, that jactory for a scientific staff provided with research labor- the teaching of science in France may be delivered soon ataries.

from all ancient fetters. Such a procedure, Prof. Lippmann went on to point out, is common in Germany and in America; and Austria ano Switzerland are, he added, adopting the same method. But

THE BRITISH ASSOCIATION. nu mention was made of Great Britain. Evidently the president felt that French disregard of the value of science

SECTION C. was reflected across the Channel, and no instance of British , enterprise seems to have presented itself to him. Germariy, however, has had the good sense to set an example

OPENING ADDRESS BY G. W. LAMPLUGH, F.R.S., to the nations. The great German manufacturing houses

PRESIDENT OF THE SECTION. low the value of the man of science. In the Zeiss works On British DRIFTS AND THE INTERGLACIAL PROBLEM. at Jena, fourteen Doctors of Science are employed, and

IF these include mathematicians as well as physicists. The

a personal reminiscence be pardonable, let me first Treat German aniline colour works employ more * scien

recall that twenty-five years ago, at a meeting of this tific" than “ technical ” chemists. At one of them, for

Section in this same room, I ventured, while still a youth, instance, fifty-five scientific and thirty-one technical chemists

to contribute my mite towards the right understanding of are engaged ; at a second, 145 scientific chemists and 175

the Yorkshire drifts. The occasion will always remain technologists ; at a third 148 scientific chemists for 75 memorable to me, for it was my first introduction to a Technicists. The research laboratories of these works are

scientific audience, and the encouraging words spoken by lavishly equipped ; one of them possesses a library of

Ramsay from this chair impressed themselves upon me 14.000 volumes; a second spends 150,000 francs a year on

and gave me confidence to persevere in the path of inglass-ware. These things are no doubt expensive, but these

vestigation. great factories still manage to pay a dividend of from

Finding myself again in these surroundings, it seems to 30 per cent.

fitting that with fuller experience and less diffidence I Every newly-discovered substance which is usable is should resume the subject by bringing before you patented, and in this way Germany has managed to estab

further results of my study of the drifts. But it is with lish a monopoly. The house of Baeyer possesses a thousand just a sigh that I recollect how on the former occasion patents at home and 1200 in foreign countries. Germany I was able to reach a definite conclusion on a simple ptported, in 1904, 195 times as much aniline colours as problem from direct observation, and had confidence that France. The German plan, said Prof. Lippmann, is a good all problems might be solved by the same method ; whereas Onr; the French method is bad.

now I find confronting me an intractable mass of facts American procedure was then described, and a word or and opinions, of my own and other people, terribly two said about the methods being adopted in Austria and entangled, out of which it seems to grow ever more difficult Switzerland.

to extract the true interpretation. French shortcomings were next passed in review and That the glacial deposits possess some quality peculiarly condemned unreservedly. French manufacturers, said the stimulating to the imagination will, I am sure, be recogpresident, consider mathematicians, physicists, and chemists nised by everyone who has acquaintance with glacialists as expensive luxuries, and engage very few of them. They or with glacial literature. The diversity and strongly do not recognise the value and significance of the dis- | localised characters of these deposits, together with their riveries of French men of science. The instance of aspect of superficial simplicity, offer boundless opportunity Carnot's researches on heat-engines was cited, and the to the ingenious interpreter ; and therefore it is not survalue they had been in England as compared with the prising that along with the rapid accumulation of facts extent to which they had been utilised in France was relating to bygone glaciation there should have arisen traced. The scientific spirit, continued the president, is much divergent opinion on questions of interpretation. Nor less developed in France than in other European countries, need we regret this result, since these differences of opinion less developed than in America and Japan. The national have again and again afforded the stimulus for research industries have suffered profoundly from this weakness, and that would not otherwise have been undertaken.

[ocr errors]


The Interglacial Problem.

evidence for the alternate extension and recession of ancient One of the most important points on which there has glaciers, fell readily under the influence of the fascinating geologists, both in this country and abroad, is with regard beyond the facts that were placed before him. been, and still is, wide difference of opinion among glacial theory brought forward by James Croll to explain the

Great Ice Age, whose interpretation, however, reached far to the value of the evidence for interglacial periods; and it will be my aim, in bringing before you some general

I need hardly remind you that, according to Croll, a

sufficient explanation of the Glacial Period could be found conclusions regarding the drifts, to concentrate attention

in certain astronomical conditions, which were shown by principally upon this evidence.

his calculations to have recurred at definite intervals, and To keep the discussion within practicable limits I must perforce assume the former extension of ice-fields over the

were supposed to have produced repeated alternations of

cold and warm climate at the opposite hemispheres during glaciated areas; for although I know that there are still dissentients from this fundamental proposition, the cumu

the course of the period. It is not iny purpose to discuss lative evidence in its favour has been so frequently re

this or any other theory regarding the cause of the Great

Ice Age, but only to direct your attention to the influence capitulated that it would not be justifiable for me to detain

of Croll's views upon the work of observation. If the you by repeating the arguments. It is now, I think, agreed by all who accept this pro

theory could have been sustained, it would have given position that the ice-sheets of the Glacial Period, though

into the hands of the geologist a first instalment of thai of vast extent, had their northern as well as their southern

absolute measure of geological time which he su ardently limits; the original idea, that they represented the outer

desires; and with this allurement it is no wonder that the portion of a polar ice-cap, having been disproved by more

theory was welcomed and hopefully put to the test. Foreextended researches in the more northerly, part of our

most among its exponents was Prof. James Geikie ; and wr hemisphere. Moreover, it has been found that these ice- geologist arose from his powerful support and masterly

must all recognise that its main importance to the field. sheets had their origin in the coalescence of masses which spread outward from separate areas of accumulation, acting

arrangement of the evidence favourable to the hypothesis, more or less independently, so that the individual sheets

It is not surprising that, amid the complicated mass of did not all attain their farthest bounds at the same time.

facts confronting us in the glacial deposits and among the But this recognition of independent centres of glaciation skilfully enwrapped, there should have been found some

voluminous literature wherein these facts are more or less has given sharper prominence to the question whether the glacial deposits are to be regarded as the product of a single glacial and interglacial stages. But the glamour of the

material to support the idea of a recurrent succession of epoch of glaciation, or whether they represent successive epochs of this kind, separated by intervals during which

astronomical hypothesis has waned, and it is recognised

that there are Haws in the physical aspect of the theory the great ice-sheets temporarily vanished. As opinion stands at present, probably most geologists worthy. I think, therefore, that the time has come when

and in its geological application that render it untrust. lean to the idea that the glaciation was interrupted by at least one interglacial epoch, during which the climate of

we should reconsider the matter in critical mood, un. any particular latitude became not less warm, and perhaps influenced by the early glow of the theory, after the wise warmer, than it now is. This is the Interglacial hypo- example of that ancient people who debated all matters of thesis in its simplest form. But it has been frequently import in two opposite frames of mind. pointed out that the criteria depended upon in the recog

On the present occasion it would be impossible adequately nition of warm interglacial conditions cannot be all assigned

to discuss the whole subject, and I propose to deal printo the same horizon,

since they recur at different positions cipally with my own experience in attempting to apply. in the drift series. Hence it has been claimed that two,

the Interglacial hypothesis to my field-work. I hope also three, four, or even five interglacial epochs, with a corre

to be able briefly to review the evidence from other parts sponding number of separate epochs of glaciation, may be

of our islands in the light of this experience. recognised in the glacial sequence. In respect to the

And here I may remind you of the important part which nuinber, relative importance, and correlation of these

this Section of the British Association has taken in the epochs or stages in different countries, or in different parts provided with funds for carrying out excavation and other

study of the subject by organising Committees of Research, of the same country, there has been, however, no pretence to agreement among the upholders of the Interglacial

necessary work. During the twenty-five years since we idea.

last met at York I find that, including the work in certain In opposition to these views of every degree, a smaller

bone-caves, there have been fourteen such committees; number of glacialists have urged that there is no proof and in many cases their operations have extended ove? of even a single absolute interruption of the glacial con

several years, so that more than thirty separate reports ditions from the beginning to the end of the period ; and

have been published in the Annual Reports of the Assoch that the evidence indicates only one great glaciation, during

ation. The precise information embodied in these reports which there were wide oscillations of the margins of the

is of high scientific value, and I am sure that these results ice-sheets in different places, due probably to more or less

are very creditable to the Section. local circumstances. This radical difference of interpretation respecting the

Classification of the Drifts. constitution of the Glacial Period assumes the greater

I have mentioned the influence of Prof. J. Geikie in the consequence in that it bears directly upon many questions establishment of the Interglacial hypothesis ; and before other than those which are strictly geological. Thus, the proceeding further it is necessary that we should reantecedents and distribution of our present fauna and flora, capitulate the scheme of classification which he has proand the time and conditions of that momentous event, the posed for the drifts on the basis of this hypothesis. This appearance of man in Northern Europe, are deeply involved elaborate scheme has been built up by a skilful combination in the issue.

of evidence gleaned from various parts of Europe, and Moreover, until we can tell whether it is one or several represents the hypothesis in its extreme form. Stated in periods of glaciation that we require, how can we approach downward succession it stands, in its latest development,' the other sciences for aid in our search for the cause of as follows:the Ice Age? It is, indeed, essential that, before seeking counsel's opinion of this kind, the geologist should have

1 Viz., Reports on “Raygill Fissure' (1813-1896); "Vanure Grace't all his evidence at command and well marshalled, so that

Wexford," &c. (1837-1890); “Welsh Caves" (1866 and 1293): "Srbin

Raised Beach" (1888-1890); “Elbolton Cave (1801-1820): "Scratis he can say such and such are the facts, and this the order Marine Drifts" (1893-1800); " Calf Hole, Skipton" (190): Hexre Plani of them. Otherwise he may receive, not the desired inter

Beds" (1890); "Trisb Elk in the Isle of Man" (1897-1900); Pleccion

cene Reds near Toronto" (1898-1000): " Moel Tryfaen Drift pretation, but advice as to what he ought to have found * Uphill (ave" (1899-1901); " Irish Caves" (1901 1904): * Kirmington and instructions to go and find it. And that such instruc- and other Fossiliserous Drifts" (1943-1005). During the same perioder tions may be detrimental rather than helpful to our progress

have also been twenty three reports of ibe " Erratic Blochi" Coonste is, I think, shown by the history of the Interglacial hypo

which bear indirectly upon the problem,

9 “ The Classification of European Glacial Deposits." Jmse to! thesis. In this matter the glacial geologists, having some (Chicago), vol. ij. (1895), pp. 241-269.


" the


[ocr errors]


EUROPEAN GLACIAL AND INTERGLACIAL STAGES (Prof. J. ously opposed by Dr. N. 0. Holst, who states his convicGEIKIE).

tion, based on the result of his observations in Greeniand,

that the so-called interglacial sands and gravels and the XI. Upper Turbarian = Sixth Glacial Period

upper moraine' of Sweden represent the residual proX. Upper Forestian = Filth Interglacial Period 1

ducts of the ice-sheet that laid down the “ lower moraine IX. Lower Turbarian= Filth Glacial Epoch

a ground-moraine. He also embraced the drifts of VIII. Lower Forestian = Fourth Interglacial Epoch

North Germany in this explanation.'
VII. Mecklenburgian = Fourth Glacial Epoch
VI. Neudeckian = Third Interglacial Epoch

Germany.-In Germany, the discussion on the “ Inter-
V. Polandian = Third Glacial Epoch

glacialismus is still in active progress. The idea of one IV. Helvetian = Second Interglacial Epoch

interglacial epoch, corresponding to the “ Helvetian” of

Prof. J. Geikie's scheme, is widely entertained ; and some
III. Saxonian =Second Glacial Epoch
II. Norfolkian = First Interglacial Epoch

geologists, influenced largely by evidence in the Alps, think
1. Scanian
= First Glacial Epoch

that an earlier interglacial stage (="Norfolkian ''), pre

ceded by a stage of glaciation (=“ Scanian ’), may have But although, as already mentioned, the Interglacial

to be admitted, though the German evidence is acknow

But Prof. Geikie's interpretation hypothesis in its simpler form has many supporters in this ledged to be imperfect. country. I do not think that the above scheme in its

of the North German drifts, on which he seeks to establish

the entirely has yet found any adherents among British

Neudeckian Interglacial ” and the Mecklenburgian glacialists. Usually, when beds supposed to be of inter

Glacial ” epochs, is strongly and authoritatively opposed. glacial age have been described by other workers, it has

In a searching criticism of these views Dr. K. Keilhack, been implied that only a single interval of milder con

of the Prussian Geological Survey,` states that no reason ditions was in mind; and even in the exceptional cases

has been found, by himself or his colleagues, for the prowhere several different boulder-clays separated by sand

posed separation of the upper drifts into these separate and gravel have been held to represent as many different

epochs; and he remarks that, on similar grounds,

so-called “last glacial epoch would have to be divided epochs of glaciation, it is rare that any attempt has been made, except by Prof. Geikie himself, to classify the sup

into four if not five epochs, so that even the most fanatical posed events in accordance with the scheme. I suppose

advocate for as many glacial periods as possible would be that most field-workers have felt, like myself, that while

terrified.” Prof. Geikie, in his reply to this criticism, some part of the classification might possibly be sustained,

brings forward the British evidence to establish the case this finished arrangement of the admittedly imperfect

in Germany, But, as we shall see, this evidence is evidence was too artificial to be accepted with confidence, especially weak, and we in this country had expected that and that it was inadvisable to allow one's self to be

the stronger proof lay in Germany, hampered, in an inherently difficult task, with further

While the supporters of the Interglacialismus difficulties that, after all, might, like “ the word Bear

thus uncertain how much of the scheme they will accept, baiting," be “ carnal and of man's creating.”

there are other geologists in Germany who repudiate the On the other hand, partly, no doubt, from the persuasive of the Ice-Age.” Among these I may mention Prof. E.

hypothesis in its entirety, and hold for the singleness manner in which its author has presented his case and his courteous readiness to meet objections, but still more

Geinitz, whose vigorous attack has been supported by Dr. from the vast extent of the field drawn upon for the argu

W. Wolff, in a useful summary of the discussion, which ment, the scheme has aroused less active criticism than

contains many references to the literature." it has, in my opinion, deserved. The critic has shrunk

Russia.-In Russia, again, opinion is divided, and the from the magnitude of the task of testing it in all its

evidence brought forward in favour of the Interglacial idea parts, while to pick out the local flaws in any particular Russian Geological Survey, who considered that, what

has been adversely criticised by Mr. S. Nikitin, of the part has seemed invidious. In taking this scheme as the basis of my examination

ever may have been the conditions farther westward, into the evidence, I am aware that the local limitations

oscillations of the ice-margin would suffice to explain the which I have set myself will be held to impair the validity

facts observed in this outer portion of the glaciated area. of my conclusions. But as there is at present in every

The Alps. In the Alps there appears to be definite


evidence for several periods of advance of glaciated country the same confusion of opinion on the Interglacial problem as in our own, and the same dis- glaciers from the mountain valleys, with intervening cussion upon the fundamental value of the evidence, it

periods of great recession, and these are supposed to appears to me that we can find strong justification for

correspond to glacial and interglacial epochs in Northern considering our own problem on its separate merits. And

Europe ; but there has been much difference of opinion the necessity for a re-sisting of the British evidence is the

respecting this evidence and its interpretation. By Profs. more urgent since it is frequently taken for granted in

A. Penck and E. Brückner, who have systematically the discussions abroad that there is a well-established

investigated the phenomena, the ice-movements are held glacial sequence in Britain, which can be called in to

to indicate four separate epochs of glaciation, with three, support the argument for other lands.

or perhaps four, warm interglacial epochs.? Not having

an opportunity to make myself sufficiently The Interglacial Problem in Other Countries. acquainted with the evidence, I may not fully recognise

its importance; but it appears to me that the factors It will serve to illustrate the condition of the problem governing the glaciation of this Alpine region may have in other countries if I refer briefly to some of the literature heen very different from those that controlled the lowland which happens to have come under my notice, though I can rarely claim sufficient knowledge of the foreign work

1 “Har det fannits mera än en istid i Sverige.” Sveriges Geologiska to discuss its value.

Undersökning, Ser. C., No. 151 (1805); and "On the Relations of the Norway.-In Norway there appears to be no direct • Writing Chalk of Tullstorp (Sweden) to the Drift Deposits, with evidence for interglacial epochs, though the existence of

Reference to the Interg'acial Question." Geol. Mag., dec. v., vol. i. (1904),

pp. 56-59. one surh epoch is supposed to be indicated by a change ? Prof. Geikie's Classification of the North European Glacial Deposits," in the direction of ice-flow, and by the presence of an

Journ. Geol., vol. v. (1807), pp. 113-125. See also discussion by H. Munthe : arctic flora at the base of the Danish peat-mosses which

“Studien über ältere Quartärablagerungen im südbaltischen Gebiete." is absent in Norway. By Dr. A. M. Hansen 2 the super

Bull. Ceol. Instit. Upsale. vol. iii. No. 5 (1896), pp. 27-114.

3 "The last Great Baltic Glacier. Journ. Geol., vol. v. (1897), pp. ficial deposits are classed as follows :-preglacial : protero- 324-339 glacial : interglacial : deuteroglacial : and postglacial.

+ "Die Einbeitlichkeit der quartären Eiszeit.” Neues Jahrb. ). MineralSweden,-In Sweden, and, I believe, also in Denmark,

ogie, &c., xvi. (1902), pp. 1-98, and other papers.

°5 ** Zur Kritik der Interglacial. Hypothese." Naturwiss. Wochenschrift. the Interglacial hypothesis is generally accepted, at least Neue Folge, Bd ii. No. 26 (1903), 14 pp. to the extent of one epoch of deglaciation, but is strenu- 0 “Sur la constitution des dépôts quaternaires en Russie, &c." Rep.

Congris Internat, a' Archeologic," Moscou, 1€92. 1 “Period" in original ; op. cit.; probably misprints for “ Epoch."

i Die Alpen im Eiszeitalter." Leipzig (1301-5), not yet complete ; for A M. Hansen, "The Glacial Succession in Norway," journ. Geol.. convenient summary see “Glazialexkursion in die Ostalpen." No. 12 of vol. i. (1891), pp. 123-144.

“Guides to Excursions of the Geological Congress," Vienna, 1903.

yet found

glaciation. And although it is certain that the great personal observation. In this case the interglacial deposit, extension of the Alpine glaciers was due to the same first described by Dr. G. J. Hinde, are magnificently *** glacial conditions that gave rise to the lowland ice-sheets posed in cliff sections at Scarboro' Heights, on the shores of Northern Europe, I do not regard it as a necessary i of Lake Ontario, near Toronto. When I visited these consequence that advances and retreats of the ice should sections under the guidance of my friend Prof. A. P. occur simultaneously in both regions. Variation in the Coleman, in 1897, they impressed me strongly, inasmuch relative amount of snowfall over the glaciated areas during as they afforded the kind of evidence for which one had the course of the Glacial Period, for which there is much sought in vain in Britain. The section around Scarboro? evidence, would be likely to produce great effects in the Heights reveals a great mass of fossiliierous stratified high-lying reservoirs of the Alps; and at the latitude of deposits, more than 180 feet thick, consisting in the lower this region we should expect rapid recession of the low- part of slightly peaty clays, and in the upper part of level glaciers in response to diminished supply. To dis- sands; and these deposits are overlain by a complex series tinguish between the effects of oscillations in precipitation of boulder-clays, with intercalated beds of sand and gravel, and of oscillations in temperature under such conditions | attaining a thickness of at least 200 feet. The fossiliferous must be peculiarly difficult.

clays are the lowest beds seen in the cliff section, but beds North America.--In North America, where both the belonging to the same series, that are exposed in the Don drifts and their literature attain gigantic proportions, the Valley, on the outskirts of Toronto, are underlain by a state of opinion is closely analogous to that among our- few feet of boulder-clay, so that it seems to be beyond selves. It is agreed by all that during the Glacial Period ques that the Scarboro' beds were deposited in an there were very extensive oscillations in the borders of the interval between two epochs of glaciation. In their upper ice-sheets; and by some geologists some of the stages of part these beds contain a flora and fauna indicating a ou recession are supposed to represent mild epochs of actual climate, but in their lower portion some of the plants and “deglaciation”; while others, fewer in number, among freshwater shells no longer exist so far north as Canada whom Mr. Warren Upham and Dr. G. F. Wright have and are therefore considered to denote a climate warmer been the most active, regard these stages as of minor than that of the present day. On this and other evidence consequence, and advocate the essential unity of the it is clear that during the course of the Glacial Period glaciation. And between the two extremes stand the great the whole of the district was for a considerable time remajority of the workers in American glacial geology, who leased from the ice-sheets which previously and afterrefrain from expressing positive opinions, but mostly lean wards covered it. Moreover, in the opinion of Prof. Coletoward the idea of at least one great interruption in the man, some of the plants and shells of the warm-climate glaciation. Some of the suggested schemes of classifi- beds denote conditions that would be incompatible with cation are fully as elaborate and complex as that pro- the persistence of ice-sheets anywhere in Canada: : and if posed for Europe, but it seems to be recognised that these this be so, then we here have proof for at least one interare only of local value. Prof. T. C. Chamberlin and his glacial epoch. But I still permit myself to feel doubt mr. fellow-workers in the North-Central States have, however, garding this last-mentioned deduction, as the shells and adopted a sequence based on the successive advance of plants in question, which have their present habitat in the different ice-lobes, which is believed to be of wider appli- | Middle United States, even yet endure winters of consider. cation; and Prof. Chamberlin has tentatively suggested able severity; and there are certain factors in the comthat some of these divisions may have their counterpart in position of the beds and their altitude above Lake Ontario the European scheme, but is careful to show that the that justify caution. It is, however, mainly from in correlation must at present remain entirely hypothetical,” knowledge of this “ Toronto formation," and of the especially as the proposed American grouping may itself Kirmington section in England, presently to be discussed, require modification.

that I still maintain an undecided attitude in respect to It is well established that the American ice-sheets, like the Interglacial hypothesis in its simpler form. their European cquivalents, radiated from several distinct Further support to the probability of an interglacial centres that attained their maximum influence consecu- epoch has been adduced from the history of the great lakers tively, and not simultaneously. Of these the “ Lauren- which formerly existed in the Interior Basin of the Western tide and the “ Keewatin " sheets had their radiants States. It has been shown by the researches of G. K. over comparatively low ground east and west of Hudson Gilbert in the “ Lake Bonneville " başin' and of I. C. Bay, while the “ Cordilleran” sheet spread outward from Russell in that of “Lake Lahontan," + that there were the Western Mountains. In his general discussion of the two separate epochs, during which these enormous basins glacial phenomena of North-Western Canada, Mr. J. B. were filled with water, and an intervening arid epoch. Tyrrells concludes that the Cordilleran sheet had reached during which they were dried up. The region is one in its greatest extent and had retired before the boulder-clay which the actual glacial phenomena are restricted to the of the Keewatin sheet was laid down; and that the Kee- mountain valleys; but as it seems evident that the lakes watin sheet, in turn, had gone south to its farthest limit, were associated in some way with the Glacial Period, the and had retired for many hundreds of miles—more than two stages of extension are supposed to represent 140 half-way to its gathering ground—before the Laurentide distinct epochs of glaciation, separated by a long intese sheet had reached its greatest extension.

glacial drought. The correlation, however, has difficulties If these conclusions be accepted, they must imply that

which very impartially discussed by Gilbert and at least in some cases the recession of the ice-lobes was Russell; and it will not admit of more than one interdue to causes acting locally, and not to mild interglacial glacial episode. periods affecting the whole hemisphere. The phenomena of invasion by successive ice-lobes in the peripheral regions The Interglacial Problem in the British Islands. might thus be readily explained without recourse to the Interglacial hypothesis.

Let us now consider the application of the Interglacial Most of the detailed evidence brought forward in

hypothesis to our own land. America to support the Interglacial idea is as fragmentary scheme through its various phases, though instructive, is

The task of following up the evolution of Prof. Geikie's and unconvincing as that of our own country. But there is one notable exception, to which I must particularly

very confusing-one might even say irritating-by reason refer, as it has been investigated by a Research Committee

of the continual changes of correlation which its author of the Association, and has, moreover,

has suggested in sorting out the British drift deposits into come under my this orderly sequence. Our East Coast bouider-class, for

example, were at one time held to cover four glacial epochs, leg, “The Diversity of the Glacial Period in Long Island," by A. C. Veatch. Journ. Geol., vol. xi. (1901), pp. 762-776.,

1 Prof. A. P. Coleman, Reps. British Assoc. for 1898, pp. 522-20: Ez 2 " Classification of American Glacial Deposits." Journ. Geol., vol. iii. 1899. pp. 411-414; for 1900, pp. 328-40; also (summary and discussi00) (1895), pp. 270-277. and in 1. Geikie's "Great Ice Age," 3rd. ed., chap. xli. "Glacial and Interglacial Beds near Toronto," Journ. Grol valu See also Chamberlin and Salisbury's recent text-book, "Geology: Earth (1901). pp. 285-310. History," vol. iii. chap. xix (London, 1906).

3"The Duration of the Toronto Interglacial Period.“ Asyra 3 • The Glaciation of North Central Canada." Journ. Geol., vol. vi. Geologist, vol. xxix. (1902). p. 79. (1898), pp. 147-161; and “The Genesis of Lake Agas-iz," ibid., vol. iv. 3 "Lake Bonneville." Monogr. U.S. Geol. Survy, vol. i (+501). (1896), pp. 811-B15.

4 "Lake Lahontan," llonogr. U.S. Gool. Survey, vol. xi. (13941




and their associated gravels to mark three mild inter- Harmer shows the probability of the transport of southern glacial epochs; and all except the first glaciation were sup- relics into this old estuarine deposit by river-drifting.' posed tu be represented in the boulder-clays of Lancashire It has, indeed, been long recognised that the marine and Cheshire. Then, somewhat vaguely, it was allowed Pliocene deposits of eastern England present us with an that perliaps there were only three separate glaciations on intelligible chain of evidence for the gradual and unthe east coast, with a minor episode of recession of the interrupted approach of the Glacial Period; and to break ice-tnargin; and the Lancashire and Cheshire boulder-clays this chain will require stronger reasons than have yet been were correlated with the two later of these glacial epochs.? | adduced. From the Coralline Crag, with seas But subsequently we are reduced in the eastern district to than at present, to the Red Crag and Norwich Crag, with two epochs of glaciation, with one mild interval, of which a northern element steadily gaining ground in the fauna, the equivalents are all recognised also in the north-west we pass upward to the Chillesford Clay and Weybourn of England."

Crag. wherein this element becomes predominant. Then While these and other similar changes may show a follows the period of slight elevation indicated by the laudable desire of their author to keep pace with the Forest Bed, wherein, along with its temperate-climate growth of definite information, I cannot help feeling that fauna, such northern forms as the musk ox and glutton Thay also show the premature character of the whole are associated ; and finally we gain just a glimpse of truly scheme, and a flexibility in it that justifies suspicion. arctic conditions in the Leda myalis bed and the Arctic Moreover, in spite of these frequent changes in the corre- freshwater bed, immediately before the advent of the great lation and this local lopping off of glacial and interglacial ice-sheet that relentlessly blotted out both land and sea. episodes, we find, with surprise, that the number of separate epochs in the classification has not diminished,

Saxonian (Second Glacial), Helvetian" (Second but has actually increased, by regrowth in fresh places.

Interglacial), and Polandian " (Third Glacial) Epochs. This, again, may betoken the inherent vitality of the scheme, in which case it will gain strength from every Regarding the glacial severity of the ensuing stage—the readjustment; but it must certainly also denote the weak- “ Saxonian Epoch ” of Prof. Geikie's scheme-all are Deas of its original basis. In considering its application to

agreed ; and from this stage onward to the close of the this country we will begin by glancing at the evidence for “Glacial Period as usually understood, or to the close of the two earliest epochs of the classification,

the “ Polandian Epoch ” of the proposed classification, our

difficulties of interpretation arise not from lack of evidence, * Scanian" (First Glacial) and Norfolkian" (First but rather from its superabundance and local intricacies. Interglacial) Epochs.

It happens, fortunately, that the great bulk of our

British drifts, with the exception only of those in certain It is acknowledged that the First Glacial Epoch is not mountainous districts, are now included by Prof. Geikie represented in Britain by any boulder-clay or other evidence within the two above-mentioned glacial epochs and the of land glaciation, but is based mainly upon the supposed intervening “ Helvetian Interglacial Epoch. Therefore, esistence of a great Baltic glacier which overflowed the

in dealing more particularly with the deposits assigned to southern part of the Scandinavian peninsula from south- these three epochs in certain typically glaciated districts, cast to north-west, a direction differing widely from that we shall bring under consideration a considerable portion of the later ice-sheets. This glaciation of Scania is sup- of the drifts of our islands, and shall obtain results which posed to have been contemporaneous with the deposition can be applied to many other areas in which the structure of the Chillesford Clay and Weybourn Crag of Norfolk, of the glacial deposits is essentially similar. The first which contain a marine fauna indicative of cold con- district to be considered shall be that which lies nearest ditions. The Forest Bed series of Norfolk, with its us; and in discussing the drifts of East Yorkshire I protemperate land fauna and flora, is then interpreted as the

pose to interweave some personal opinions that I have product of a mild interglacial epoch ("* Norfolkian '') inter- deduced from the facts, which will afterwards be given calated between the “ Scanian glaciation and the more wider application. severe

Saxonian glaciation which followed ; and it is implied that during this mild stage the earlier ice-sheet East YORKSHIRE DRIFTS.—The long cliff-sections between vanished.

the Humber and the Tees constitute one of the best exSo far as I can gather, the recognition of the Scanian

posures of lowland drifts in Britain, or even in Europe. ice-sheet rests on dubious grounds, being based chiefly on They fortunately include some deposits which reveal the the disputed supposition that the lower boulder-clay of conditions prevailing in the neighbouring part of the North North Germany is not the equivalent of the lower boulder- Sea basin just before the great glaciation; and they thereclay of Sweden, but of a subsequent Swedish boulder-clay. fore enable us without interruption to continue the history For the Norfolkian disappearance of the first Swedish begun in East Anglia. ice-sheet no direct evidence is forthcoming, since it is The old cliff of chalk and the marine beach at its foot acknowledged that no interglacial deposits representing which lie buried at Sewerby, on the southern side of Flamthis stage have been found in Sweden. But the Norfolk borough Head, under sheets of boulder-clay and gravel, Forest Bed is here brought into the argument to prove the prove to us that at the very beginning of glacial times the "' deglaciation”-so that the Scandinavian geologist is North Sea still held possession of its basin, and with a invited to accept the “ First Interglacial Epoch mainly surprisingly slight difference from its present level. A on the supposed strength of the British evidence, while few far-transported stones in the old beach denote that the British geologist is expected to acknowledge the “ First ice-fioes sometimes drifted southward into Holderness Bay ; Glacial Epoch on the supposed strength of the Swedish while the bones of animals in the shingle, and in the evidence. This method of argument might have weight blown sand which overlies it, prove that among the if the evidence afforded by either region were perfectly denizens of the neighbouring land were the elephant definite. But in the present instance the conclusion that (E. antiquus), rhinoceros (R. leptorhinus), hippopotamus the Forest Bed represents an interglacial episode is not (H. amphibius), and bison. This fauna is frequently conarceptable to the observers who have the fullest knowledge sidered to be proof of mild conditions of climate ; but from of the Norfolk sections, Mr. Clement Reid pointing out the mode of its occurrence in this and other places, I can that the enclosing of the North Sea by the union of Britain find no reason to doubt that these animals inhabited the with the southward continental land affords an adequate country, perhaps as seasonal migrants, until the time that explanation of the apparent climatal discrepancy between it was actually covered by the encroaching ice-sheets. the fauna of the sea and that of land *; while Mr. F. W. And here I may note my opinion, that throughout the

[ocr errors]
[ocr errors]

discussion of our glacial deposits too much weight has been 1 "Great Ice Age," and ed (1877), p. 393. *" Prehistoric Europe" (1881), pp. 263-266.

allowed to the deductions regarding climate based upon 3 "Great Ice Age,” 3rd. ed. (1894), chaps. xxv. and xxvi., and Journ. scanty indications afforded by the ancient fauna and flora. 6col. (supra cit.). 4 "The Pliocene Deposits of Britain." Men, Geol. Survey (1890), pp. 1 "The Later Tertiary History of East Anglia." Proc. Geol. Assoc.,

vol. xvii. (1902), p. 449.

1d6- 190.

« PreviousContinue »