Sept. 20, 1888] 



NATURE 



505 



are so numerous that one hardly knows where to draw the limits ; 

 according to one plan, the use of seventy-six signs and hatchings 

 would be required. You will be able to judge of the various 

 methods proposed by the fine plates which illustrate the Reports. 

 The sections given of some of the mountains of Switzerland, 

 and others which serve as specimens, have an excellent effect. 

 Conventional signs are also made use of to indicate the strike and 

 dip of the strata, faults, fossiliferous localities, sources of cold, 

 thermal, and mineral springs, travertines, quarries, mines, &c. A 

 geological map will thus be a veritable hieroglyphic chapter, with 

 a universal signification. 



As a result of the discussions at Bologna, and with a 

 view to a practical application, it was decided to publish a 

 geological map of Europe on the scale of 1/1,500,000, in which 

 the scale of colours used would be that definitely adopted by the 

 Congress. This map, of which the execution is well advanced, 

 is under the direction of a Committee at Berlin. 



With respect to the unification of geological terms, Reports 

 were received from nine National Committees, viz. from Austria, 

 Belgium, Spain, Portugal, France, Great Britain, Hungary, 

 Italy, Russia, and Switzerland. Besides these, eleven have been 

 received from individual members. It can be well imagined 

 that with so many opinions they were not all in agreement, but 

 with the good will shown by everyone, although there were 

 differences on points of detail, they were almost unanimous on 

 the essential points, and a preliminary general agreement was 

 arrived at for the stratigraphical terms, such as system, group, 

 series, stage ; and for chronological terms, such as era, epoch, 

 age, &c, leaving to future Congresses the consideration of certain 

 subordinate points. This subject reminds me, gentlemen, of a 

 difficult question which has yet to be faced. If your resolutions 

 are carried by the votes of all the members of Congress, the 

 result must be affected by the varying number of the nationalities 

 in the changing places of meeting. For example, at Bologna 

 there were 149 Italian members and 19 English ; at Berlin there 

 were 163 Germans and II English ; here, on the contrary, we 

 are . . . English and . . . foreign geologists. Therefore, if 

 all vote, the opinion of the seat of the Congress may too much 

 preponderate unless you find means of placing some limits 

 upon it. 



Thanks to the loyalty of the Bologna Council, the greater 

 number of the resolutions were carried unanimously, a few 

 only were referred to various Committees for future con- 

 sideration. 



With respect to the stratigraphical divisions it was resolved : — 



(1) That the term "group" should be applied to each of the 

 great divisions of Primary, Secondary, and Tertiary rocks. 



(2) That the subdivisions of these groups should be named 

 "systems." You have thus a Primary or Palaeozoic group, 

 and the Silurian system, the Jurassic system. (3) As to the 

 divisions of first order of the systems, the term " series " was 

 applied (the Oolitic series) ; to those of the second order, the 

 term "stage" (the Bajocian stage) ; and to those of the third 

 order the word " zone " (the zone of Ammonites humpkresianus). 

 The unity of the stratified masses is the stratum or bed. With 

 regard to a word much in use in England, and dating from the 

 primary period of geology — the word "formation," the majority 

 of the Congress decided not to employ it in the sense of terrain 

 in French, as we do, but only in the sense of origin or mode of 

 formation, and so on. It is necessary, therefore, to seek some 

 word to replace with us the familiar terms of "Chalk formation," 

 " London Clay," &c. 



For the chronological divisions corresponding with the strati- 

 graphical, it was proposed that (1) "era'.' should correspond 

 with "group," as the Primary era, the Secondary era; (2) 

 "period "with "system," as the Silurian period, the Creta- 

 ceous period ; (3) " epoch" with "series," as the Lower Oolitic 

 epoch, the Lower Cretaceous epoch; " age " with "bed," as 

 the Portlandian age, the Bathonian age, &c. 



On the subject of colours and signs, the final decision was 

 remitted to the Committee of the Geological Map ; and with 

 regard to the rules to be followed in the nomenclature of species, 

 it was resolved that the name attached to each genus and to 

 each species should be that by which they have been earliest 

 known, on the condition that the characters of the genus and 

 species have been published and clearly defined. The priority 

 not to date beyond Linnaeus, twelfth edition, 1 766. 



There were only four special and local memoirs presented to 

 the Congress at Bologna, and these were in support of collections 

 and documents exhibited. 



The Berlin Congress. — The official Proceedings of this ses- 

 sion having only been issued during the last few days, were not 

 available when this address was prepared. I have therefore had 

 recourse for information to the independent notices of Messrs. 

 Penevier, Klebs, Choffat, Frazer, Blanford, and Dewalque. 

 At Berlin, special attention was given to the construction of the 

 geological map, of which the Committee, profiting by the liberty 

 given to it by the Bologna Congress, revised the colours for the 

 sedimentary series in the following manner : — 



1. Recent deposits (Alluvium, &c.) Very pale cream colour. 



2. Quaternary (Diluvium) Naples yellow. 



3. Tertiary Various shades of yellow. 



4. Cretaceous Green tints and hatchings. 



5. Jurassic Blue tints. 



6. Triassic Violet tints and dots. 



7. Permian and Carboniferous ... Gray tints and hatchings. 



8. Devonian Brown tints. 



9. Silurian Grayish-green tints. 



10. Archaean Rose tints. 



And for the ten divisions of eruptive rocks, various brilliant and 

 dark red tints and points. 



In the use of monograms to accentuate the tints, it was de- 

 cided to employ Latin initials for the sedimentary deposits, and 

 Greek initials for the eruptive rocks. 



It is on this plan that the large and grand geolo<jical map of 

 Europe in course of execution at Berlin is to be coloured, and of 

 which the publication will realize one of the principal practical 

 objects of the Congress — the unification of the colours employed 

 in geology. 



As to stratigraphical unification, the Congress adopted, for the 

 most part, the resolutions passed at Bologna. But the French 

 and Portuguese Committees proposed to substitute the term 

 "series "for " group " in the first and third great divisions of 

 sedimentary strata ; thus, instead of Primary group, Secondary 

 group, &c, it will be Primary series, Secondary series, &c. 

 The word "group" will then take the place of divisions of 

 systems, such as Oolitic group instead of series. This replacement 

 will perhaps recommend itself to many of us. 



Further, the Committees were not unanimous on the proposi- 

 tion to substitute, for the various existing terminations of systems, 

 homophone terminations in ic. Instead of speaking of the 

 Eocene, Cretaceous, Carboniferous, Silurian, &c. , system, it was 

 proposed to use the terms Eocenic, Cretacic, Carbonic, Siluric, 

 &c, system. Is it essential thus to change the ancient ensigns 

 of our science ? Etymology is lost, and signification destroyed. 

 It is well to have these terminations for things positive, such as 

 the crystalline and eruptive rocks — for example, granitic rocks, 

 porphyritic rocks, basaltic rocks — for here it indicates their charac- 

 ters ; but can we subject, or is it needful to subject, several 

 series of deposits that have no character in common to the same 

 rigid rule, from the circumstance that they all come under the 

 same ideal classificatory name ? This question will be discussed, 

 and it is for you, gentlemen, to judge what solution may be the 

 most advisable. 



Among other subjects, gentlemen, that you will have to con- 

 sider, is that of the classification of the Cambrian and Silurian 

 strata. According as these two great systems have been taken in 

 descending or ascending order, the boundary between the two 

 has been placed lower or higher, because the discordances 

 between the series are rare, and the palaeontological chain 

 between the two systems is but little interrupted. In England, 

 Sedgwick, who commenced from below, found himself stopped 

 by no discordance until he reached the Mayhill Sandstone, 

 whereas Murchison, who commenced from above, saw no reason 

 to stop until Palaeozoic life failed him ; he hesitated, therefore, 

 where to place his base line. In the same way, in those 

 countries where they followed Murchison, whose classification 

 was better known, the stratigraphical barriers were, according 

 to the partisans of the one, passed over ; whilst, according to the 

 partisans of the other, there was an absence of palaeontological 

 proofs. . In this country — their native stratigraphical country — 

 the Cambrian and Silurian occupy comparatively a small area ; 

 and it is only since the death of their founders that the palaeonto- 

 logical proofs have been increased to an extent sufficient to bring 

 out clearly their distinctive characters. These two systems are 

 found elsewhere (especially in America, where it is a question 

 whether they should be associated with a Taconic system), either 

 better developed, or with special characters which may help to 



