346 



SCIENTIFIC NEWS. 



[Sept. 28, 1 883. 



Ordovician, but kept to Murchison's classification, and 

 desired to include in the Cambrian the Olenellus beds. 



Professor Gosselet, of Lille, objected to the newer 

 classification, because the fauna of the so-called Ordo- 

 vician is so nearly related to the Upper Silurian. Pro- 

 fessor Lapworth's protero and deuterozoic seemed to him 

 also unwise, on account of the great development of the 

 Devonian out of England, as in the Ardennes. 



Professors Dewalque and Kayser spoke in the same 

 sense. 



Dr. A. Geikie, Director-General of the Geological Sur- 

 vey, referring to his long connection with Sir Roderick 

 Murchison and the general acceptance of the views of 

 the latter, stated that while he was quite willing to 

 change his opinions on due cause being shown, he did 

 not find a sufficient reason in this case. He expressed 

 regret that Professor McK. Hughes, the present head of 

 the Sedgwickian school, had been obliged to leave the 

 Congress, and thought the question could not be settled 

 in his absence. As to the term Ordovician, he considered 

 it absolute nonsense, and thought the classification of 

 Murchison sufficiently clear and well known. 



Professor Blake, of Nottingham, who followed, was 

 the first English member who used the French language, 

 the previous English speakers' remarks, however, 

 being, on the proposition of Professor de Lapparent, 

 summarised in French in a most lucid and admirable 

 manner by Professor C. Barrois, of Lille. While sup- 

 porting Professor Lapworth's views, Mr. Blake would 

 add a fourth fauna, that containing Olenellus, to which he 

 would apply the name Monian. 



Professor de Lapparent, of Paris, urged the desirability 

 of deciding whether the Cambrian should only include 

 fossiliferous strata or should extend down to the crystal- 

 line schists. 



Mr. Delgado referred to the classification in three 

 divisions adopted in the Portuguese map. 



Mr. Hull objected to the term Ordovician, on the 

 ground that there was no serious reason for its introduc- 

 tion, and because the Lower Silurian of Murchison had 

 priority, besides being adopted all over the Continent. 



Professor Barrois pointed out that the term Silurian, 

 as used on the Continent, did not lend itself to synonymy, 

 as it corresponded to both the Ordovician and Upper 

 Silurian. 



Mr. Gilbert, of Washington, U.S.A., desired to hear 

 the opinions from all parts of the world. It was well, 

 he thought, not to settle the terminology by reference to 

 one locality only, and, if possible, only after extended 

 investigation, as in each locality the limits of the beds 

 were different. 



As there seemed no prospect of a general agreement, 

 the Chairman decided not to put it to the vote. 



After referring to the death, since the Berlin meeting, 

 of M. Fontannes, he made a proposition, which Dr. 

 Sterry Hunt seconded, to send a telegram, in the name 

 of the Congress, to Boella, the birthplace of Quintina 

 Sella, the geologist, where a monument to the latter was 

 to be unveiled on the following day. 



On Wednesday the basis of the discussion on Crystal- 

 line Schists was supplied by eight monographs by 

 authors of well-proved ability. Dr. Sterry Hunt 

 communicated a paper on the crystalline schists, 

 setting out with a summary of the theories on their 

 origin. He pointed out that the geologists of our 

 day are divided into two classes, as long as they 



admit for these rocks an igneous (Plutonic) origin, or an 

 aqueous or so-called Neptunian origin. Among the 

 Plutonists there are still two schools, the one regarding 

 the foliaceous structure of these schists as due to the 

 lamination of an igneous mass submitted to a strong 

 pressure. For this school the crystalline schists as well 

 as the granites, the trachytes and the basalts, are eruptive 

 rocks. This manner of explaining the origin of the 

 crystalline schists may be called the exoplutonic or 

 volcanic. For the other Plutonian school, these same 

 crystalline schists are the products of the consolidation 

 of the igneous matter of the globe beneath a crust formed 

 by surface-cooling ; the schistous structure being the 

 result either of currents established in the mass still 

 liquid and heterogeneous, or of a segregation in the mass 

 during crystallisation. To this second igneous school 

 may be given the name Endoplutonic. 



The Neptunists on their part are divided into several 

 schools. Werner and his disciples believed that the 

 crystalline rocks, both granitic and schistous, have been 

 deposited successively from a universal ocean, which they 

 conceive as a chaotic liquid holding in solution the ele- 

 ments of all the primitive rocks. This supposed deriva- 

 tion by a slow crystallisation from a primordial chaos 

 may be named the chaotic hypothesis. Into this purely 

 Neptunian hypothesis the notion of a fiery centre does 

 not enter, but certain Platonists who admit this notion 

 have devised a thermochaotic hypothesis, propounded by 

 Poulett Scrope in 1825, and subsequently maintained by 

 Daubree. 



Another Neptunian school was that of Hutton, who 

 supposed that the crystalline rocks are derived from the 

 consolidation and crystallisation, by the action of internal 

 heat, of the sediments deposited by the water at the 

 bottom of the sea, these sediments being the detritus, 

 either of the endoplutonic or the exoplutonic rocks. This 

 view, which the author calls the metamorphic hypothesis, 

 has the defect of not taking account of the chemical 

 changes which the bulk of the silicates undergo during 

 the degradation of the crj'stalline rocks and their trans- 

 formation into sands and clays. 



Dr. Sterry Hunt, among these hypotheses, gave the pre 

 ference to that of Werner. He did not, indeed, venture, 

 in the present state of our chemical knowledge, to sup- 

 pose all these bodies simultaneously present in solution, 

 even at the elevated temperature which the thermo- 

 chaotic hypothesis supposed. But he sought to conciliate 

 with the known facts the notion that a great part of the 

 primary rocks, both granitic and schistous, had passed 

 through the state of an aqueous solution. To this hypo- 

 thesis he gave the name eremitic. A full discussion of 

 this view may be found in the author's work " Mineral 

 Physiology and Physiography." 



Professor Albert Hein discussed the classification of 

 the crystalline schists. He concluded that the texture of 

 the crystalline schists of the Alps had been variously 

 modified by dynamo-metamorphosis. 



Professor Lory examined the constitution and the 

 structure of the mountain masses of crystalline schists 

 of the Western Alps. He pointed out that a substitution 

 of chloritic schists by protogine in the mountain mass 01 

 Pelvoux, as in that of Mont Blanc, presents itself pre- 

 cisely along the intra-alpine limit of the Mont Blanc zone, 

 a limit marked by a grand fault, which may be followed 

 for more than sixty leagues from Fallouise to Airdo. 

 Between the two sides of this great fault are observed the 

 striking contrasts of the rudimentary trias of the zone ot 



