•554 



NA TURE 



[October 5, 1893 



and therefore to make thick sediments, otherwise the sediments 

 quickly rise to sea-level, and stop the process of sedimentation 

 at that place. But it is precisely a want of complete isostasy 

 which is necessary to make an isostatic slope landward. Button 

 refers to Herschel as having suf;gested a similar cause of strata 

 crumpling and slaty cleavage {Phil. Mag. vol. xii. p. 197, 1856) ; 

 but the principles involved in the two cases are almost exactly 

 opposite. Herschel supposes sediments to slide down steep 

 natural slopes of sea-bottoms, and therefore sea-ward. Button 

 supposed sediments to slide up natural, though down isostatic 

 slopes, landward. Herschel's is a theory of strata-crumpling 

 and slaty cleava;;e. Button's a theory of mountain formation. 



"There has been no attempt to carry this idea of Button's to 

 quantitative detail. It was probably thrown out as a suggestion 

 in mere despair of any other explanation, for he had already re- 

 pudiated the contractional theory. But the least reflection is 

 sufficient to convince that such slight want of complete isostatic 

 equilibrium as may somelinifs occur, would be utterly inade- 

 quate to produce such effects." 



///. Reyer's Gliding Theory.'^ 



" Prof. Reyer has recently put forward certain views fortified 

 by abundant experimenis on plastic materials. His idea in 

 brief seems to be this: strata are lifted and finally broken 

 through by uprising fused or semi-fused matters, and these 

 appear above as the granitic axis. As the axis rises, the strata 

 are carried upward on its shoulders, until when the slope is 

 sufficiently steep the strata slide downward, crumpling themselves 

 into complex folds and exposing the granitic axis in width pro- 

 portioned to the amount of sliding. 



" No doubt there is much value in these experiments of Reyer, 

 and possibly such gliding does indeed sometimes take place in 

 mountain strata, and some foldings may be thus accounted for. 

 But the great objections to this view are : (l) that there is no 

 adequate cause given for the granitic uplift, and (2) that it 

 utterly fails to account for the complex foldings of such moun- 

 tains as the Appalachian and Coast Range, where there is no 

 granite axis at all. Reade, indeed, holds that the Piedmont 

 region is the granite axis of the Appalachian, and that the 

 original strata of the eastern slope are now buried beneath the 

 sea. But American geologists are unanimous in the belief that 

 the shore line of the great interior Palaeozoic Sea was but a 

 little east of the Appalachian crest and the sea washed against 

 land of Archaean rocks extending eastward from that line." 



Conclusion. 



"After this rapid discussion of alternative theories, in which 

 we have found them all untenable, we return again to the 

 contraction theory, not indeed with our old confidence, but 

 with the conviction that it is even yet the best working 

 hypothesis we have." 



GEOGRAPHY AT THE BRITISH 

 ASSOC! A TION. 



/\ S in other sections, an absence of sensational papers, and 

 ■^ an unusual abundance ol good solid work, the outcome 

 of study and research, were the characteristic features in 

 Section E. The president's address was well adapted to his 

 audience ; the simplicity of its language, and the vivid de- 

 scriptions of scenes in the Arctic Basin, with which it abounded, 

 sustained the attention of every listener, and went over the head of 

 none. Perhaps it was better calculated for the extension than the 

 advancement of geographical science, but in many ways advance 

 in geography depends on conditions different from those which 

 determine advance in other sciences. Mr Seebohm rightly felt 

 that to enforce principles familiar to professed geographers by a 

 picturesque concrete example which no one could misunderstand 

 was better than to record advances in specialised research, which 

 could only appeal to the few geographers whose grasp of the 

 subject equalled his own. 



The section met on four days, and, including the presidential 

 address, twenty-seven papers were read ; a large number of mem- 

 bers, in addition, took part in various discussions. A feature of 

 the papers was the small number of mere records of travel, and 

 the general striving after some kind of scientific elaboration of 

 the data described. This was in some cases imperfectly done, 



1 Nature, vol. xlvi. p. 224, iSgj, and vol. xlvii. p. Si, 1892. 



NO. 1249, VOL. 48] 



but the imperfection was a consequence of the neglect of higher 

 geographical education in this country, and the necessary beat- 

 ing out of new paths by independent workers, who, seeing the 

 need for scientific treatment, are not always sure of the right 

 methods to employ. 



An inter-sectional discussion with Section C, on the limits 

 between physical geography and geology, had been looked for- 

 ward to with much interest, but proved somewhat disappointing. 

 Few of the speakers addressed themselves to the subject 

 announced, and in the extempore speeches it was evident that 

 after a faint attempt to come to the point, there was a tendency 

 to fall off on some familiar tack, and repeat irrelevant phraser 

 often said before. In fact, there was no true discussion, as there 

 was no distinct issue put forward. 



Mr. Clements R. Markham, F.R.S., president of the 

 Royal Geographical Society, commenced the proceedings 

 by reading a paper, put together with consummate skill, 

 in which he argued for the limit of human testimony as 

 the line of demarcation between the domains of physical 

 geography and geology. Thus he established a purely chrono- 

 logical division between phenomena of the same kind, which 

 would fall to the province of one science or the other, according 

 to the date of their manifestation. He concludes — 



" Meanwhile, and until better instructed, I should define 

 geology as the study of the condition of the earth and of the 

 changes on its surface during the cycles of ages before the dawn 

 of history ; and I should define physical geography as a know- 

 ledge of the earth as it is, and of the changes which have takei> 

 place on its surface during historical times. These changes, 

 derived from human testimony, explain to us the laws according 

 to which similar changes are now taking place around us. 



"The two sciences depend upon each other, and are very 

 closely allied. The geologist finds the same phenomena in the 

 rock formations of the pastas the physical geographer discovers 

 on the surface of the earth of the present. Both, for example, 

 have the duty laid upon them of seeking out the agencies which 

 rule in the processes of upheaval and depression. The fold, 

 with its crest and trough, is common to both sciences ; and 

 geographers have rejoiced at the announcement of ' a wedding- 

 ring of geology and geography uniting them at once and for ever 

 in indissoluble union.'" 



Mr. W. Topley, F. R.S., who followed, admitted the very 

 close relations of geology and physical geography, but he 

 devoted his attention to establishing the closeness of this 

 relation by bringing forward numerous instances of the 

 dependence of geographical features on geological structure, 

 rather than to defining the limits of the two departments. His 

 contention was that they merged the one into the other, and 

 were not merely contiguous subjects separated by a discoverable 

 line. Mr. E. G. Ravenstein supported Mr. Markham's chrono- 

 logical boundary, and summed up the conclusions of a racy 

 speech in the statement that geology stands to physical geography 

 in precisely the same relationship as history does to political 

 geography. Prof. C. Lapworth, F.R.S., acknowledged the great 

 difficulty of finding any satisfactory dividing line, contending 

 that the geologist is in many ways absolutely dependent on the 

 physical geographer, and the physical geographer in his turn 

 absolutely dependent on the geologist, the physical geography 

 of the present being indissolubly bound np with the physical 

 geology of the past. Prof. Valentine Ball contended that the 

 relation between geology and geography was similar to that 

 between anatomy and art. Br. R. D. Roberts, viewing geology 

 as the history of the earth, argued that physical geography was 

 merely the last chapter ol^ that history. Br. H. R. Mill sug- 

 gested that a definition between the two departments of know- 

 ledge might be found rather in the aspect in which the phe- 

 nomena of the earth were viewed than in the subject-matter or 

 in chronological order. Physical geography being concerned 

 with the present forms of the earth's surface borrowed from 

 geology an explanation of the observed facts, taking results but 

 not copying methods. Mr. II. Yule Oldham spoke of the unity 

 of geography and of the importance of studying old travels ia, 

 order to keep a record of recent physical changes. Prof.] 

 Bonney, F.R.S., characterised the discussion as waste of time 

 and a search after the unattainable, for the words geography 

 and geology contained in themselves all the definition that was 

 required or could be found. Colonel Godwin-Austen and Mr. 

 J. Y. Buchanan, F. R. S., made a few remarks ; and Sir Archi- 

 bald Geikie, who, by the consent of the presidents of Sections C 

 and E, occupied the chair, summed up in a judicial manner. He 



