474 



NA TURE 



[April 1 6, 1874 



surface was carried down through the gorge to be added to the 

 old delta cf the river. At last the major part of the Miocene 

 rocks that partly occupied the plain were worn away and the 

 plain has been reduced to its present temporary level ; while the 

 terraced hills on either bank still remain to attest the amount of 

 watery degradation that the area has undergone. 



So much for the scooping out of the valley. But there 

 is another point which I would like to impress upon you. 

 On each side of the Rhine there are important tributary 

 rivers. Thus, for example, above the gorge we have the Jlaine, 

 the Neckar, the Kinzig, the Elz, and other streams, flowing 

 through deep steep-sided valleys ; and these rivers have 

 from a very early period been tributaries of the Rhine. 

 It follows, then, that when the level of the Rhine was 

 400 or 500 ft. higher than at present the levels of the bottoms 

 of these rivers must also have been 400 or 500 ft. higher than 

 at present; and therefore, just in proportion as the great valley 

 of the plain of the R.hine was being cut down and lowered, so in 

 proportion must the valleys in which these rivers run have 

 gradually been deepened. When we come to the gorge the 

 same kind of argument applies to the Moselle and other tribu- 

 taries of the Rhine. 



I have elsewhere attempted to show that at one time the 

 Moselle ran as high as the top of the table-land that now bounds 

 it on each side. Everyone who knows that river is aware that, 

 though It looks so hilly when we go up the stream in a steam- 

 boat, as soon as we reach the edges of the slopes on either side 

 we are on the top of a great table-land intersected by numerous 

 valleys, so that before the gorge of the Rhine was formed the 

 Moselle ran at as high a level as the ancient Rhine ; and just as 

 the gorge of the Rhine was being deepened, so the Moselle was 

 by degrees also en.abled to deepen its channel. The same was 

 the case with other rivers, right and left of the Rhine ; and by 

 applying this principle to the other great rivers of Europe we 

 may hope in the long run to explain the physical history of all 

 the systems of drainage of all parts of the continent. 



One other point remains to be stated with regard to the 

 physical history of the Rhine. Geologists well know that in 

 older times the glaciers of Switzerland ^v^re on an immensely 

 larger scale than at present. Large as they appear to us at the 

 present day, they are of pigmy size when compared with their 

 magnitude at a comparatively late period of the world's 

 history. The Rhone glacier then spread across all the 

 area now occupied by the Lake of Geneva, till it abutted 

 on the Jura ; and the old Rhine glacier extended all 

 over the Lake of Constance, and reached at least half way 

 from Schaffhaussen to Basle. The body of water which flowed 

 directly from such glaciers must have been very great, and enor- 

 mous must the moraines have been that were shed from the ice- 

 sheets. From an examination of the pebbles that form the 

 superficial gravel on the present plain of the Rhine below Basle, 

 it is certain that a large portion of them have come from the 

 Alpine regions. .Such a great moraine as was shed from the 

 western edge of the old glacier of the Rhine was constantly 

 being attacked by the waters that flowed from its end, and thus 

 by degrees pebbles were carried onward into the plain. The 

 result is that a large part of the* gravels of the Rhine is 

 simply the w'aste of old moraines shed from the glaciers of 

 Switzerland, added to by material carried down by the streams 

 of the Vosges and the Schwartzwald, also partly derived from 

 the moraines of ancient glaciers on a smaller scale. 



Last year it was my lot to deliver here a lecture on the history 

 of old continents, and I attempted to show that one old conti- 

 nent in particular retained its identity through a very long period 

 of geological time ; that from the close of the Upper Sflurian 

 period, all through the Old Red Sandstone and Carboniferous 

 periods, through' the Permian and New Red Sandstone epoclis, 

 over great part of vvliat is now Europe, that continent, with many 

 physical changes, still retained its identity. Such a vast conti- 

 nent remaining through all those geological periods implies a 

 succession of epochs of lime, which, as far as years and cycles of 

 years are concerned, the mind has as yet only hints of data which 

 some day may help us to grapple with such a problem, and not 

 till astronomy comes more boldly to the help of geology, may we 

 begin to hope for the solving of the problem of the actual value 

 of geological time. However that may turn out, it is certain 

 that during the long continental epoch alluded to there were, over 

 and over again, many changes in physical geography far greater than 

 that petty change which I have been endeavouring to sketch out 

 to-night. The floras and faunas of the world in that old time 

 changed, not in the minor degree I have been speaking of to- 



night, but were more completely remodelled again and again in 



great part, even generically. Mountain ranges ro- c, glacial periods 

 intervened and passed away. Great lakes, sometimes fresh, 

 sometimes salt, appeared and were oblUerated by great terres- 

 trial changes. At one time vast lakes, like those of the heart 

 of Africa and North America, covered prodigious areas of land ; 

 at another, equal or larger areas were covered by salt lakes 

 as large as the Caspian and the Sea of Aral. And when 

 you think of the continental episode in the modern 

 geological history of Europe to which I have drawn atten- 

 tion, you will see how small it really is, though it may look 

 large to our minds, compared to the old continental epoch of 

 which I spoke last year. This you may depend upon, that 

 though to the superficial eye it may seem as if the world had 

 always been going on just as it is doing now, and tliat through 

 all time to come it will go on just the same, with iis mountains, 

 valleys, rivers, lakes, and seas, yet it is umuc the less certain that 

 changes, such as I have described to-night, are but the forerun- 

 ners of other mutations as great, aye, and far greater, that will 

 take pkace in the future. Just as there is as yet no certainly 

 measured limit to the geological time of the past, so also we 

 know of no measurable limit to geological time to come. But 

 why should I keep you with words such as these, when I may 

 convey a whole chapter in physical geology, condensed into eight 

 lines, by the greatest of our living poets : — . 



Tliere rolls the deep wflere grew the tree. 



< ) Earth, what changes hast thou seen ! 



There, where the long street roars, hath beeu 

 Tlie stillness of the central sea. 

 The hills are shadows, and they flow 



r'rom form to form, and nothing stands : 



They melt like mist, the solid lands. 

 Like clouds they shape themselves and go. 



SCIENTIFIC SERIALS 



In' the Journal of Botany for March, the editor. Dr. Trimen, 

 commences a series of useful articles (which is continued in the 

 Apiil number) on the Botanical Bibliography of the British 

 Counties, being a list of country and district floras arranged topo- 

 graphically. The other paper of greatest interest in this num- 

 ber is one of a kind of which this very useful journal has now 

 published a considerable number, and which may ultimately 

 throw considerable light on some of the problems connected with 

 the distribution of plants. On the Flora of the Leeds and Brad- 

 ford District, by J. A. Lees. — The number for April commences 

 witli an article of some importance in systematic botany, A Re- 

 vision of the genera DryobaUinops and Dipterocarpus, by Prof. 

 Thiselton-Dyer, in which a number of new species are described, 

 incUiding two belonging to the previously monotypl; genus 

 Z'rr<Vw/(!/w/ij', and illustrated by a plate (two moi- > iag pro- 

 mised in the next number). Tire editor also gives \\\ i:iii num- 

 ber one of the most valuable specialities of the journal, his list 

 of New Species of Phanerogamous Plants in periodicals pub- 

 lished in Great Britain during 1S73. 



The Scottish Natnralist for April publishes a number ot 

 papers on almost every branch of Botany and Zoology, in- 

 cluding one on Geology, of more or less interest to Scottish 

 nattiralists. — Mr. J. A. Harvie Brov/n proposes the establish- 

 ment of a Natural History Publication Society, something on 

 the model of the original plan of the Ray Society, for the pur- 

 pose of publishing original papers on Natural History, princi- 

 pally on Mammalia and Aves, and for reprinting in fac-simile 

 rare and useful tracts, pamphlets, &c., on the like subjects. — We 

 have also further instalments of tlie lists of the Lepidoptera and 

 Coleoptera of Scotland, by Dr. Buchanan White and Dr. D. 

 Sharpe. This quarterly magazine seems to fill a most useful 

 place in forming a channel of intercommunication between natu- 

 ralists north of the Tweed. 



Mcniork Jdla Soc. degli Spectroscopistl Italian!, December. 

 This number contains a paper be G. Lorengoni, On the Obser- 

 vation of a partial eclipse of the sun in May last, observed by the 

 spectroscopic and direct view methods. He discusses at length 

 the advant.ages and accuracy of each method, and concludes that 

 the former method is the best of the two. — G. de Lisa gives a 

 table of spots on the sun, observed at Palermo in December, 

 giving a mean of about eight spots each day. 



The January number contains a note that a new Spectroscopic 

 .Station has been established at Turin, and an equatorial by 

 Fraunhofer has been erected there. — Prof Draper contributes a 



