284 



NATURE 



[September i, 1910 



words, the sands and gravels, presumably (often certainly) 

 mid-glacial, mantle, like the Upper Boulder Clay, over 

 great irregularities of the surface, and are sometimes 

 found, as already stated, up to more than 1200 feet. 

 Either of these deposits may have followed the sea-line 

 upwards or downwards, but that explanation would almost 

 compel us to suppose that the sand was deposited during 

 the submergence and the upper clay during the emergence, 

 so that, with the former material, the higher in position 

 is the newer in time, and with the latter the reverse. 

 We must not, however, forget that in the island of RiJgen 

 we find more than one example of a stratified gravelly 

 sand between two beds of Boulder Clay (containing 

 Scandinavian erratics) which present some resemblance to 

 the Boulder Clays of eastern England, while certain glacial 

 deposits at Warnemiinde, on the Baltic coast, sometimes 

 remind us of the Contorted Drift of Norfolk. 



Towards the close of the Glacial Epoch, the deposition 

 of the Boulder Clay ceased ' and its denudation began. 

 On the low plateaux of the Eastern Counties it is often 

 succeeded by, coarse gravels, largely composed of flint, 

 more or less water-worn. These occasionally include 

 small intercalations of Boulder Clay, have evidentiv been 

 derived from it, and indicate movement by fairlv strong 

 currents. Similar gravels are found overlying the Boulder 

 Clay in other parts of England, sometimes at greater 

 heights above sea-level. Occasionally the two are 

 intimately related. For instance, a pit on the broad, 

 almost level, top of the Gogmagog Hills, about 200 feet 

 above sea-level and four miles south of Cambridge, shows 

 a current-bedded sand and gravel, overlain by a Boulder 

 Clay, obviously rearranged, while other pits in the 

 immediate neighbourhood expose varieties and mixtures of 

 one or the other material. But, as true Boulder Clay 

 occurs in the valley below, these gravels must have been 

 deposited, and that by rather strong currents, on a hill- 

 fop — a thing which seems impossible under anvthing like 

 the existing conditions ; and, even if the lowland were 

 buried beneath ice full 200 feet in thickness, which made 

 the hill-top into the bed of a lake, it is difficult to under- 

 stand how the waters of that could be in rapid motion. 

 Rearranged Boulder Clays also occur on the slopes of 

 valleys- which may be explained, with perhaps some of 

 the curious sections near Sudbury, by the slipoing of 

 materials from a higher position. But at Old Oswestrv 

 gravels with indications of ice action are found at the 

 foot of the hills almost 700 feet below those of Gloppa. 



Often the plateau gravels are followed at a lower level 

 by terrace gravels,^ which descend towards the existing 

 rivers, and suggest that valleys have been sometimes 

 deepened, sometimes only re-excavated. The latter gravels 

 are obviously deposited by rivers larger and stronger than 

 those which now wind their way seawards, but it is 

 difficult to explain the former gravels bv anv fluviatile 

 action, whether the water from a melting ice-sheet ran 

 over_ the land or into a lake, held up by some temporary 

 barrier. But the sorting action of currents in a slowly 

 shallowing sea would be quite competent to account for 

 them, so they afford an indirect support to the hvpothesis 

 of submergence. It is, however, generally admitted that 

 there have been oscillations both of level and of climate 

 since anv Boulder Clay was deposited in the districts south 

 of the Humber and the Ribble. The passing of the Great 

 Ice .Age w-as not sudden, and glaciers may have lingered 

 in our mountain regions when Pal.-colithic man hunted 

 the mammoth in the valley of the Thames or frequented 

 the raves of Devon and Mendip. But of these times of 

 transition, before written history became possible, and of 

 sundry interesting topics connected w^ith the Ice .Age itself 

 -^f its cause, date, and duration, whether it was per- 

 sistent or interrupted by warmer episodes, and, if so, by 

 what number, of how often it had already recurred in the 

 history of the earth — I must, for obvious reasons, refrain 

 from speaking, and content myself with having 

 endeavoured to place before you the facts of which, in my 

 opinion, we must take account in reconstructing the 



> Probably deposits of a di'tlnctlv Rlacial oriem (such as tho-e ne.->r 

 Hessle in Yorkshire) continued in ihe northern cistricts, but on these «e 

 need not linger 



= For instance, at Stanringfield in the v.illey of ihe T.ark. 



■' These contain the instruments worked bv pa'a*oli-hi'' fArhenlean) man 

 who, in this country at any rate, is later thin'the chalky boulder c'ay. 



physical geography of Western Europe, and especially of 

 our own country, during the Age of Ice. 



Not unnaturally you will expect a decision in favour of 

 one or the other litigant after this long summing up. 

 But I can only say that, in regard to the British Isles, 

 the difficulties in either hypothesis appear so great that, 

 while I consider those in the " land-ice " hypothesis to 

 be the more serious, I cannot as yet declare the other 

 one to be satisfactorily established, and think we shall be 

 wiser in working on in the hope of clearing up some of 

 the perplexities. I may add that, for these purposes, 

 regions like the northern coasts of Russia and Siberia 

 appear to me more promising than those in closer 

 proximity to the North or South Magnetic Poles. This 

 may seem a " lame and impotent conclusion " to so long 

 a disquisition, but there are stages in the development of 

 a scientific idea when the best service we can do it is by 

 attempting to separate facts from fancies, by demanding 

 that difficulties should be frankly faced instead of being 

 severely ignored, by insisting that the giving of a name 

 cannot convert the imaginary into the real, and by 

 remembering that if hypotheses yet on their trial are 

 treated as axioms, the result w'ill often bring disaster, like 

 building a tower on a foundation of sand. To scrutinise, 

 rather than to advocate any hypothesis, has been my aim 

 throughout this address, and, if my efforts have been to 

 some extent successful, I trust to be forgiven, though I 

 may have trespassed on your patience and disappointed a 

 legitimate expectation. 



Section A. 



MATIIEM.HTICAL ANU PHVSICAL SCIENCE. 



Opening Address liv Prof. E. W. HoiisoN, Sc.D., 

 F.R.S., President of the Section. 



Since the last meeting of our .Association one of the 

 most illustrious of the British w'orkers in science during 

 the nineteenth century has been removed from us by the 

 death of Sir William Muggins. In the middle of the last 

 century Sir William Huggins commenced that pioneer 

 work of examination of the spectra of the stars which has 

 ensured for him enduring fame in connection with the 

 foundation of the science of Astrophysics. The exigencies 

 of his work of analysis of the stellar spectra led him to ■ 

 undertake a minute examination of the spectra of the 

 elements with a view to the determination of as many 

 lines as possible. To the spectroscope he later added the 

 photographic film as an instrument of research in his 

 studies of the heavenly bodies. In 1.864 S'"' \\'illiam 

 Huggins made the important observation that many of 

 the nebulae have spectra which Ci)nsist of bright lines, 

 and two years later he observed, in the case of a new 

 star, both bright and dark lines in the same spectrum. 

 In 1868 his penetrating and alert mind made him the first 

 to perceive that the Doppler principle could be applied to 

 the determination of the velocities of stars in the line of 

 sight, and he at once set about the application of the 

 method. His life-w^ork, in a domain of absorbing interest, 

 was rewarded by a rich harvest of discovery, obtained as 

 the result of most patient and minute investigations. The 

 " Atlas of Representative Stellar Spectra," published in 

 the names of himself and Lady Huggins, remains as a 

 monumental record of their joint labours. 



The names of the great departments of science. Mathe- 

 matics, Physics, Astronomy, Meteorology, which are ' 

 associated with Section. .\, are a sufificient indication of 

 the vast range of investigation which comes under the 

 purview of our Section. k\\ opinion has been strongly 

 expressed in some quarters that the time has come for" 

 the erection of* a separate Section for Astronomy and 

 Meteorology, in order that fuller opportunities may be 

 afforded than hitherto for the discussion of matters of 

 special interest to those devoted to these departments of 

 Science. I do not share this view. I believe that, whilst 

 the customary division into sub-sections gives reasonable 

 facilities for the treatment of questions interesting solely 

 to specialists in the various branches with which our 

 Section is concerned, a policy of disruption would be 

 injurious to the wider interests of science. The close 

 association of the older .\stronomv with Mathematics, and 

 of the newer .\strononiy with Pliysics, form strong pre- 



NO. 2 13 I, VOL. 84] 



