Nov. II, 1880] 



NATURE 



Z7> 



Geological Changes of Level 



In a most friendly notice in your la'.t issue of the Memoirs 

 forminw the fir»t volume of the oflicial Report of the 

 Challenger Expedition, Prof. Huxley takes exception to a 

 sentence in my short Introduction. "There seems to be 

 sufacient evidence that all chan.ei of level since the close of 

 the PaL-eozoic period are in direct relation to the present coast 

 lines," and he asks in what possible sense this can be the case. 



I fully admit the criticism, and that the sentence as it stands 

 does not explain itself. 



That it is not a relation of ordinary parallehsm Lyell s and 

 D'Orbigny's maps of old coast- lines, a map published by myself 

 in "The Depths of the .Sea," and particularly the beautiful later 

 maps of Jurassic, Cretaceous, and Tertiary France by M. Delesse, 

 abundantly show. I have explained my idea of the relation in 

 position between the recent deposits and those of the Tertiary 

 and Secondary periods in "The Depths of the Sea" (pp. 472-476) 

 at some length. I believe that the Jurassic, the Cretaceous, and 

 the Tertiary formations are essentially 7«<ir^;V/f7.' deposits, and that 

 their belts of deposition form approximately a series of contour 

 bands upon an elevation which has persisted throughout a long 

 series of local and general oscillations, the sum of which has 

 raised the wliole through a small vertical range. Such oscilla- 

 tions have also, doubtless, affected the bottom of the sea, but no- 

 where to such an extent as to modify in any important degree 

 the conditions of the abyssal region. 



Prof. Huxley says, " There is nothing, so far as I am aware, in 

 the biological or geological evidence at present accessible, to 

 render untenable the hypothesis that an area of the mid-Atlantic 

 or of the Pacific sea-bed as big as Europe should have been 

 upheaved as high as Mont Blanc and have subsided again any 

 time since the Palaeozoic epoch, if there were any grounds for 

 entertaining it." I think however he will admit that the follow- 

 ing Challenger data, if they can be established, afford at least a 

 presumption against an oscillation of such a kind, at all events in 

 post-Triassic times, beyond which it is difficult to stretch even the 

 imagination. 



The careful researches of my colleagues, Mr. Murray and the 

 Abbe Renard, with which I have had the advantage of being 

 familiar during their progress, have led us to the belief that (i) 

 the chalk of the Cretaceous period was not laid down in what we 

 now consider deep-water, and that its fauna, consisting mainly 

 of shallow-water forms, merely touches the upper limit of the 

 abyssal fauna ; and (2) that no beds exist in the series of known 

 sedimentary rocks which correspond in composition and in 

 structure with the beds now in process of formation in the abyssal 

 sea (" The Atlantic," vol. ii. p. 299). 



The hypothesis of the elevation of a mass of land equal to 

 Em-ope and as high as Mont Blanc in the middle of one of the 

 great ocean basins could in our present state of knowledge be 

 defensible only on the supposition that it was a phenomenon of 

 the same order as the elevation of some portion of our existing 

 continental land, and there is now, to say the least, grave reason 

 for doubting that any rock which is due to accumulations formed 

 at depths over 2500 fathoms, the average depth of the basins to 

 which Prof. Huxley refers, enters into the composition of any 

 existing continent. The present land consists of a set of crystal- 

 line rock-axes of various ages, with a long succession of sedi- 

 mentary deposits, all of which give evidence of having been laid 

 down in water of moderate depth, piled up upon and against 

 them. Such a hypothesis therefore, besides being without a 

 single fact in its support, would be met by a strong adverse 

 argument from analogy, and would be, so far, in a worse 

 case than the hypothesis of the origin of species by natural 

 selection. 



I thoroughly agree, however, with my friend Prof. Iluxley 

 that "the value of the great work which is now being brought 

 before the public does not lie in the speculations which may be 

 based upon it, but in the mass and the solidity of the permanent 

 additions which it makes to our knowledge of natural facts," 

 and I imagine that all of us who are engaged in that work look 

 upon it as our first and paramount duty to present these natural 

 facts which have been acquired as simply and as effectively as we 

 can. Still the generalisations or impressions, or whatever they 

 may be, of tlie few men selected to observe these facts are as 

 much a part of the result of the Expedition as anything else, and 

 I think it is also our duty to offer them to our fellow-workers for 

 what they are worth. C. Wyville Thomson 



Bonsyde, Linlithgow, November 6 



" The first Volume of the Publications of the 

 ' Challenger ' " — A Correction 



There is a typographical error in my notice of the Challenger 

 publications, published in last week's Nature, for which I 

 should, of course, be disposed to blame the printer, had it not 

 been hinted to me that my handwriting is sometimes not so clear 

 as might be wished. 



I appear (p. 2) to agree with the proposition that " the deep-sea 

 fauna presents us with many forms \\ hich are the dried and but 

 little modified descendants of Tertiary and Mesozoic species." 



As few things can be much wetter than the inhabitants of the 

 ocean abysses, this opinion seems to be, to say the least, eccentric. 



But "dried" should have been printed "direct," which was 

 the word denoted by my graphic symbols. T. H. IIuxLEY 



4, Marlborough Place, Abbey Road, N.W,, November 7 



Correspondence of Phenomena in Magnetic Storms 



The Astronomer-Royal having lately received from the 

 Observatory of Zi-ka-wei, in China (latitude 31° 12' north, 

 longitude, from Greenwich, Sh. 6m. east), lithographed copies 

 of the photographic traces of the declination and horizontal force 

 magnets, extending from August 11 to 14, and from August 17 

 to 20 of the present year, has placed them in my hands for 

 comparison witH the Greenwich records. Some particulars of 

 this comparison are herewith annexed. Greenwich time is used 

 throughout. 



A general examination of the two sets of curves shows that 

 the disturbances were usually greater in magnitude at Greenwich 

 than at Zi-ka-wei. Comparing the curves in detail, it is found 

 that on August 11, at 10.20' a.m., after a quiet period, the 

 declination and horizontal force magnets at Greenwich both 

 made a sudden start, which was the commencement of a magnetic 

 disturbance, lasting until midnight. An apparently equally 

 sudden start (from a quiescent state), in both declination and 

 horizontal force, is shown on the Zi-ka-wei curves, occurring in 

 declination at 10.12 a.m., and in horizontal force at 10.20 a.m. 

 (as nearly as the small scale on w'hich the curves are drawn will 

 allow measures to be made). This first motion was to decrease 

 the west declination and increase the horizontal force at both 

 places. A bold motion in the two Zi-ka-wei curves at 11.30 

 a.m. (increase of declination, decrease of horizontal force) has 

 corresponding decrease of horizontal force at Greenwich, not 

 accompanied, however, by much motion in declination. And of 

 numerous fluctuations occurring at Greenwich between noon and 

 midnight of the same day, some appear to correspond with 

 motions at Zi-ka-wei, whilst others do not. 



A calm state follows at both places, until near noon of August 

 12. On this day at about 1 1.40 a.m. the magnets at Greenwich 

 made a further start, and until 4 p.m. the movements were large. 

 A corresponding start is also shown in both the Zi-ka-wei curves 

 (commencing, according to the register, some minutes sooner 

 than at Greenwich), the movements following being similarly 

 large. Afterwards, until 6 a.m. of August 13, considerable 

 osc7llation was nearly continually shown at Greenwich, there 

 being especially a large change of declination between 7 and 9 

 p.m.°( August 12) ; but there is no strongly-marked motion at the 

 latter time at Zi-ka-wei, and the changes are throughout much 

 smaller than at Greenwich. Later on August 13 further oscil- 

 lations occur at both places, but the separate motions .are in no 

 particular accordance. The period of disturbance seems defi- 

 nitely to come to an end at both places at 6 a.m. on August^ 14. 



A period of quiet is broken at Greenwich on August iS, at 

 1.45 p.m., by a sharp though small movement both in declina- 

 tion and horizontal force (increase of both). There is a corre- 

 sponding sharp increase (after quietude) of horizontal force at 

 Zi ka-wei, but no change of declination. A bold increase of 

 declination and decrease of horizontal force at Greenwich at 7 

 a.m. of August 19 is accompanied by a similar decrease of hori- 

 zontal force°at Zi-ka \\ei, but with little change of declhiation. 

 Bolder changes occur at the latter place at noon, but wilh com- 

 paratively small change at Greenwich. The magnets become 

 quiet at both places at or near midnight of August 19. 



The general result of this comparison of Greenwich and Zi- 

 ka-wei curves appears to be that, after a quiet period, the first 

 indication of disturbance, if sudden (it need not be large) occurs 

 simultaneously or nearly so at both places, but that during the 



■ Approximately stated to be 10.30 in my previous letter (Natuhe, vol. 

 xxii. p. 361), .-.nd so quoted by Mr. Whipple (p. 55S). The ume above given 



