208 



SCIENCE. 



[Vol. IV., No. 83. 



questions of the science, — Sir William Thomson's 

 interesting speculations, founded upon physical phe- 

 nomena, respecting the probable size of the atom; 

 and Helmholtz's discussion of the relation of elec- 

 tricity and chemical energy ; and the theory of the 

 vortex-ring constitution of matter, thrown out by Sir 

 William Thomson, and lately worked out, from a 

 chemical point of view, by J. J. Thomson of Cam- 

 bridge. 



Another branch of chemistry which has recently 

 attracted much experimental attention is that of 

 thermo-chemistry, — a subject upon which, in the 

 future, the foundation of dynamical chemistry must 

 rest, and one which already proclaims the truth of 

 the great principle of the conservation of energy, in 

 all cases of chemical as well as of physical change. 

 But here, although the materials hitherto collected 

 are of very considerable amount and value, the time 

 has not yet arrived for expressing these results in 

 general terms ; and we must therefore be content to 

 note progress in special lines, and wait for the ex- 

 pansion into wider areas. 



In conclusion, Professor Roscoe spoke of the part 

 English chemists had played in the past, and of the 

 marked difference between the data-gathering Ger- 

 man work, and the systematizing of the facts known, 

 which is going on in England. He also referred to 

 what he considered the best method of educating 

 chemists, — by giving them as sound and extensive a 

 foundation in the theory and practice of chemical 

 science as their time and abilities will allow, rather 

 than forcing them prematurely into the preparation 

 of a new series of homologous compounds, or the in- 

 vestigation of some special reaction, or of some pos- 

 sible new coloring-matter, though such work might 

 doubtless lead to publication, — and called attention 

 to the prominence of English industrial chemistry. 



THE CORRELATION OF GEOLOGICAL 

 FORMATIONS. 1 



This address was devoted to a consideration of a 

 few remarkable exceptions to the rule that similarity of 

 faunas and floras in fossiliferous formations through- 

 out the surface of the world implies identity of geo- 

 logical age. Some interesting contributions have 

 been made to this question by the geological survey 

 of India, where Mr. Blanford's experience has been 

 chiefly derived, and by the geologists of Australia and 

 South Africa; and he first noticed a few typical in- 

 stances, several of them Indian, in which the system 

 of determining the age of various formations by the 

 fauna or flora has led to contradictory results, and 

 then showed where the source of error appears to lie. 

 The famous Pikermi beds of Greece, a few miles east 

 of Athens, contain a vertebrate fauna nearly always 

 quoted as miocene; but they overlie strata with well- 

 proved pliocene marine Mollusca. The Siwalik beds 

 that flank the Himalaya north of Delhi are still 



1 Abstract of an address to the geological section of the British 

 association at Montreal, Aug. 28, 1884, by W. T. Blanford, 

 F.R.S., Sec. 7, Gr.S., F.R.G.S., president of the section. 



classed as miocene by most European writers, but 

 are regarded as pliocene by the Indian survey, on 

 evidence found by tracing them west and south into 

 Sind. The Gondwana system of central India, a 

 great sequence of fresh-water beds probably of fluvi- 

 atile origin, over 20,000 feet thick, is of unusual 

 interest on account of the extraordinary conflict of 

 paleontological evidence it presents to the observer. 

 Its subdivisions are numerous, and vary in almost 

 every place of occurrence. One (the Talchir beds) 

 contains rounded bowlders chiefly of metamorphic 

 rocks up to six feet across, embedded in fine silt: 

 others are characterized by an intermingling of floras 

 and faunas that give rise to a mass of contradictions ; 

 beds with a Triassic fauna overlying . others with 

 Rhaetic or Jurassic floras. The Australian coal- 

 measures and their associated beds present even a 

 more remarkable instance of homotaxial perversity, 

 a Jurassic flora being of the same age as a carbon- 

 iferous marine fauna. Some of these beds (Hawkes- 

 bury) again contain transported bowlders, which 

 occur once more in the lower members (Ecca beds) 

 of the Karoo formation of interior South Africa. The 

 latter presents a striking likeness to the Gondwana 

 system of India. In both countries, a thick fresh- 

 water formation occupies a large area of the interior 

 of the country, whilst on the coast some marine 

 Jurassic and cretaceous rocks are found; and as in 

 India, so in South Africa, the uppermost inland mes- 

 ozoic fresh-water beds are capped by volcanic. 



Other examples of discrepancies in paleontologi- 

 cal evidence might be given, but he would add merely 

 a mention of the single case known to him in which 

 the discordant records are both marine, namely, Bar- 

 rande's 'colonies' in Bohemia; but here the dis- 

 cordance is much less than in the cases before cited, 

 and moreover Barrande's conclusion is disputed by 

 other observers. 



In most of the cases he had named, the conflict is 

 between the evidence of marine and terrestrial or- 

 ganisms. Manifestly one or the other of these leads 

 to erroneous conclusions ; and in making choice be- 

 tween the two, most geologists accept evidence of the 

 marine fossils. The reason is not far to seek. So 

 far as he was aware, no case is known where such an 

 anomaly as that displayed in the Gondwanas of India 

 has been detected amongst marine formations of 

 which the sequence was unquestioned. Further, if 

 we compare the distribution of marine with that of 

 terrestrial and fresh-water animals and plants at the 

 present day, we shall find a very striking difference ; 

 and it is possible that this difference may afford a 

 clew to the conditions that prevailed in past times. 



Wanderers into what they fancy unexplored tracts 

 in paleontology are likely to find Professor Huxley's 

 footprints on the path they are following. In his 

 paper on the Hyperodopedon, he says: " It does not 

 appear to me that there is any necessary relation 

 between the fauna of a given land and that of the 

 seas on its shores. . . . What now happens geo- 

 graphically to provinces in space, is good evidence as 

 to what, in former times, may have happened to 

 provinces in time ; and an essentially identical land- 



