NATURE 



629 



THURSDAY, OCTOBER 25, 1906. 



7 //it GEOLOGICAL HISTORY OF SEA-LEVEL. 



riie Face of the Earth {Das Antlitz der Erde). By 

 Prof. Eduard Sucss. Translated by Dr. Hcrtha 

 I>. C. .SoUas, under the direction of Prof. W. J. 

 Sollas. Vol. ii. Pp. vi + 556 ; illustrated. (Oxford: 

 Clarendon Press, igo6.) Price 255. net. 



THE first volume of this translation has been 

 previously reviewed in Nature, and we can 

 renew our congratulations to the translator on her 

 admirable rendering of this great work. Prof. Suess's 

 eloquence depends on his ideas and his poetical 

 imagery, and thus his writings suffer less by transla- 

 tion than those of most men. Doubt may be felt 

 u liether some of the proposed equivalents of technical 

 terms, and such words as quer-Andian, will be gener- 

 .-lUv adopted in English. In reading the volume it is 

 necessary to remember that the original was pub- 

 lished eighteen years ago. The French translation, 

 edited by M. de Margerie, was brought up to date 

 and illustrated by additional maps; but this edition 

 e.\actly follows the original, and does not even add 

 the date of its first publication. We are, however, 

 frequently reminded of its age by such statements as 

 that the Arctic Ocean is " of very trifling depth," or 

 that the author cannot hazard a guess as to the struc- 

 ture of the Celebes. In many cases the facts stated 

 are now known to be incorrect ; but later research has 

 removed Prof. Suess's difficulties probably more often 

 than it has added to them. 



The main purpose of this volume is the statement 

 iif the evidence for .Suess's contention that continents 

 .•ire never uplifted in mass, and that the occurrence of 

 raised shore lines and horizontal sheets of marine 

 rocks is due to the lowering of sea-level, and not to 

 the raising of the land. Suess, therefore, returns to 

 pre-Plavfairian geology, for Playfair maintained that 

 the level of the land is less stable than that of the sea. 

 This apparentlv improbable conclusion became, owing 

 tn the brilliant advocacy of Lyell, the fundamental 

 principle of the Uniformitarian school of geology. 



The contrary view was dismissed by Herbert 

 .Spencer as one of the gratuitous assumptions of what 

 he called " illogical geology." Nevertheless, it is 

 now advocated bv the geologist who has probably 

 the widest general acquaintance with geological litera- 

 ture, and is gifted with a scientific insight that has 

 materially advanced each of the many branches of 

 geology to which he has given his attention. 



Prof. Suess's argument is that a continental uplift 

 i> impossible. .X continent may subside, but it cannot 

 be uplifted in mass. Rocks may be raised locally 

 when uptilted during the formation of a mountain 

 chain ; but he denies the possibility of the uniform 

 uplift of widespread masses composed of irregular 

 m.iterials. The sea has certainly encroached at times 

 upon the land, and has at others receded; but instead 

 nf these changes being due to the sinking and rising 

 of the land, Suess maintains that they are due to 

 i.iriations in sea-level. 



That the sea-level is not uniform is indisput.able. 

 NO. 1930, VOL. 74] 



It varies from causes which need only to be stated 

 to be accepted. The water is heaped up in places by 

 wind and rivers. Elsewhere it is lowered by rapid 

 evaporation, and the surface is maintained at the 

 lower level by the greater weight of the Salter water. 

 Thus the surface of the Mediterranean, according to 

 Suess, is funnel-shaped, the lowest part of the funnel 

 being in the area of especially salt water in the neigh- 

 bourhood of Crete. Variations in wind and rainfall 

 or in the course of rivers; the reduction in the lateral 

 attraction of the l.iiid, in consequence of its denuda- 

 tion ; the retardation of an on-shore current by in- 

 creased friction due to shoaling, may all lead to a 

 local retreat of the sea. Thus Suess attributes a raised 

 beach near Bombay to sedimentation having checked 

 the incoming tide, and thus caused a local depression 

 of sea-level. The apparent effect of these causes on 

 the shore-line would be the same as that produced by 

 an actual uplift of the land. As the retreat or 

 advance of the shore-line may be produced by the 

 oscillation either of the land or of the sea, Suess 

 objects to the usual terminology, which always speaks 

 of the uplift or subsidence of the land. To avoid 

 unproved assumptions he speaks of negative and 

 positive movements, according as the sea-level falls 

 or rises relatively to the adjacent land. Sir Archi- 

 bald Geikie has suggested terms — the emergence and 

 submergence of the land — which are equally non- 

 committal, and have the advantage of being self- 

 explanatory. The encroachment or retreat of the sea 

 mav be a merely local incident or it may be a world- 

 wide phenomenon ; in the latter case, Suess speaks of 

 it as a eustatic movement, and explains it as due to 

 an increase or reduction in the capacity of the ocean 

 basins. A negative movement, i.e. an emergence of 

 the land, would be caused by an increase in the depth 

 of the oceans by a subsidence of their floor, which lets 

 the water fall away from the land. 



This volume may be considered in two sections ; in 

 the first chapters Prof. Suess states his heterodox doc- 

 trine, and the mass of stratigraphical evidence in its 

 support. In the second section he examines the lead- 

 ing cases relied on bv the champions of secular eleva- 

 tion of the land. These two sections of the book 

 appear of unequal value, for they deal with movements 

 of probablv different character and origin. The first 

 part describes the great movements of emergence and 

 submergence which are world-wide in their range ; 

 Suess's greatest service to geology has been his re- 

 cognition of this fundamental fact and its conse- 

 quences. It is a most helpful discovery, and Prof. 

 Suess offers us the only reasonable explanation yet 

 advanced. The evidence is summarised by Suess in 

 chapters ii. to vi. of this volume. Therein he describes 

 and compares in detail the coasts of the Atlantic and 

 the Pacific, and gives a summary of the geological 

 history of the oceans. The striking resemblance in 

 the lithological succession in some of the geological 

 systems in remote parts of the world can only be ex- 

 plained on the assumption that they are controlled by 

 .some world-wide agency; this, Suess's fundamental 

 proposition, seems to be supported by the general 

 evidence of stratigraphical geology. 



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