NATURE 



i«i 



THURSDAY, DECEMBER i6, 1909. 



PAL.EOZOIC .STRATIGRAPHY. 



Traitd de Giolo^ie. \\A. ii. Les Pcriodes g-co- 

 logiques. Fasc. i. Hy Prof. Emile Haiig. Pp. 

 539-928- (Paris : A. Colin, 1908.) Price 9 francs. 



THE first volume of Prof. Haug's treatise on geo- 

 logy was noticed in {vIature last year (vol. 

 Ixxviii., p. 123), and we now welcome the first part of 

 (he second volume, as it is as suggestive, and will no 

 doubt be as useful, as its predecessor. The first volume 

 deals with historical geology, and its first part de- 

 scribes the geological systems— of which the time 

 equivalents are technically valued as periods— from the 

 beginning of the geological record until the end of 

 the Trias. The book continues Prof. Haug's valuable 

 summaries of recent work, his judicious selection of 

 new significant facts and figures, and it is rich in 

 well-reproduced* illustrations. It has the merit of 

 being a very cheap text-book, as, though it includes 

 392 closely printed pages and twent3'-eight excellent 

 plates illustrating rocks, fossils and scenery, its pub- 

 lished price is only 9 francs. A feature in the first 

 volume that we remarked with regret was the scanty 

 reference to British work; this volume is a great 

 improvement in that respect, as British geology re- 

 ceives its fair share of attention, though the author 

 must have missed several important recent memoirs 

 or he would not have remarked that Carboniferous 

 pateoritology has been for a long time past neglected 

 in this country or inserted the footnote on p. 763. 

 The author does not always select for reference the 

 most valued British results, for he quotes Monian and 

 Arvonian, and omits some later more useful terms. 



The PalcEozoic he divides into four systems — 

 Cambrian, Silurian, Devonian, and Anthracolitic. He 

 subdivides the Silurian into two subperiods, the 

 Ordovician and Gothlandian, and as he admits that 

 they arc independent, both stratigraphically and 

 pateontologically, it may be regretted that he does 

 not accept them as distinct systems; for if the name 

 Gothlandian continues to increase in favour, there 

 is a danger that when the two divisions are accepted 

 as separate systems, the term Silurian will fall 

 altogether into disuse. The Devonian system the 

 author adopts mainly on stratigraphical grounds, as 

 he remarks that the fauna alone is insufificient to 

 justify the distinction, as it is so poor in families 

 special to the period. 



The volume begins with an introduction to the 

 principles of stratigraphy, and then describes the geo- 

 logical periods in turn. Prof. Haug explains the 

 gradual recognition of the scientific basis and world- 

 wide value of the divisions between the geological 

 systems, for they are due to movements which affected 

 the world as a whole, and by modifying geography 

 and climate produced simultaneous changes in the 

 contemporary faunas and floras. In his account of 

 each system he begins with the history of its classifi- 

 cation and nomenclature ; he then gives a list of 

 characteristic genera and some notes on the life of 

 the period, illustrated by numerous woll-selcctcd 

 NO. 2094, VOL. 82] 



figures, such as Ruedemann's Siphonophora-like 

 colony of graptolitcs with its float. Then follows a 

 brief summary of the distribution of the system 

 through the world, with especial reference to the types 

 of sediments and the relation of the rocks to the 

 transgressions and retreats of the sea. Finally, he 

 gives a sketch of the climate, zoological provinces, 

 and distribution of ocean and continent in the period. 



Prof. Haug divides pre-Cambrian time into only 

 two periods, the Archaean and Algonkian. The term 

 Archaean he uses in the sense defined by its founder 

 Dana; he does not go with those — an increasing 

 number — who subdivide the .Archaean into two groups, 

 a lower for the massive basal rocks and an upper for 

 the pre-Algonkian schists. The Algonkian he accepts 

 for the comparatively unaltered pre-Cambrian sedi- 

 ments, such as our Torridon sandstone. 



One unorthodox feature in the author's classifica- 

 tion is his acceptance of one system, for which he 

 adopts Waagen's name Anthracolitic, to include both 

 the Carboniferous and Permian. The suggestion to 

 unite them has been so often made that it is clear 

 that the evidence on its behalf is weighty. It is true 

 that the invertebrate fauna of the Permian is not 

 by itself sufficient to characterise a special geological 

 system, but the great geographical changes and the 

 important development of the vertebrates are strong 

 arguments in favour of maintaining the Permian as 

 a system. The author practically describes the 

 Carboniferous and Permian apart, and together they 

 would make a system inconveniently large and varied. 



In the names of the series into which the systems 

 are divided Prof. Haug attaches great weight to 

 priority; thus he rejects the Mississippian of Prof. 

 II. S. Williams because the name had been employed 

 before in a different sense by Marcou, and he appears 

 to regret that he cannot adopt Missourian, instead of 

 the less convenient Uralian, on the ground that the 

 latter is a year older. But as the author rejects 

 Bernician, owing to its having been less adequately 

 defined than the later term Dinantian of de Lap- 

 parent, he fortunately allows some discretion in the 

 selection of names. He, however, appears disposed, 

 as a straligrapher, to pick up the heavy burden of 

 priority which paleontologists are now preparing to 

 throw off. 



The account of each geological system concludes 

 with a sketch of its climate, biological provinces, and 

 geography, and the author's work shows the rapid 

 growth in our knowledge of these interesting sections 

 of the earth's history. He directs attention to the 

 numerous Palaeozoic glaciations, now proved, in- 

 cluding the Huronian described by Coleman at 

 Cobalt, in Canada, the Cambrian discovered by How- 

 chin in South Australia and by Bailey Willis in 

 central China, the Devonian found at Cape Town by 

 Rogers, and the long-known Upper Paleeozoic 

 glacials of India, South Africa, and Australia. He 

 rejects the explanation of the last as due to the shift 

 of the South Pole into the Indian Ocean, and 

 attributes the glaciations that occurred in at least 

 four areas of Gondwanaland to geographical causes. 

 He notices the indications of various Palaeozoic 

 deserts, but does not mention the desert theory in 



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