September i6, 1897] 



NATURE 



485 



The wealth of material brought forward left but little time for 

 the final discussirn, but the whole sitting was practically a 

 debate on the subject by the authors of the numerous papers. 

 Prof. F. C. Chamberlin led the way with a professedly highly 

 speculative thesis— a group of hypotheses bearing on climatic 

 changes — which turned mainly on the question of the origin 

 and persistence of the various constituents of the atmosphere, 

 more especially of the carbonic acid. The author made a com- 

 plete departure from the common view, by supposing the 

 atmosphere to have begun as a tenuous envelope which has 

 been subjected to depiction and enrichment during all sub- 

 sequent time. The author has been led to a rejection of the 

 nebular hypothesis, in favour of the theory of the growth of the 

 earth by the ingathering of solid and gaseous particles. An 

 application of these principles resulted in the conclusion that a 

 glacial climate might be brought about by the impoverishment 

 of the carbonic acid of the air ; and a whole cycle of recurrent 

 climatal changes was postulated on this basis. 



In his next paper Prof Chamberlin was content to 

 confine himself to more mundane methods, and gave an 

 able dissertation on the distribution and succession of the 

 Pleistocene ice-sheets of the northern United States, illus- 

 trating, by means of a large map, the looped moraines which 

 encircled the terminations of the various lobes. Prof C. H. 

 Hitchcock described the southern lobe of the Laurentian ice- 

 sheet in New P2ngland, laying especial stress on the great up- 

 lift of the Laurentian boulders in their southward course, and 

 the divergence of the striiv towards the termination of the lobe 

 " like the barbs of a feather from the central shaft." Prof. H. 

 LeRoy Fairchild discussed the general phenomena of the glacial 

 geology of Western New York, bringing out forcibly the effect 

 of the south-moving ice-sheet from the Ontario- Erie basin in 

 damming the north-tlowing drainage south of these lakes, so as 

 to form temporary bodies of fresh-water which emptied south- 

 ward across the water-shed at every col, cutting characteristic 

 rock-channels now dry. Mr. F. B. Taylor gave an account of 

 the Champlain submergence and uplift, and their relations to the 

 Great Lakes and Niagara P'alls, in which the point of chief im- 

 portance was the description of an old channel by which all the 

 great lakes, except Erie, formerly drained through the Nipissing 

 outlet into the Ottawa river, thus enormously reducing the volume 

 of Niagara, and consequently affecting very seriously any calcu- 

 lation as to the time occupied in the wearing back of the Niagara 

 ( iorge. This Nipissing outlet Mr. Taylor believes to have been 

 iinally closed by differential uplift, a factor which all the 

 American geologists seem to recognise and allow in relation to 

 y;lacial and post-glacial geology. 



Prof. A. P. Coleman gave a lucid description of the glacial 

 and inter-glacial deposits at Toronto. The recognised import- 

 ance of these deposits to the vexed question of inter-glacial 

 periods led to the formation of a Committee with a grant of 20/. to 



' further investigate their flora and fauna. Dr. J.W. Spencer brought 



forward fresh evidence from the West Indies and elsewhere in 

 !avour of the continental elevation during the Glacial Epoch. 

 At a later session Mr. J. B. Tyrrell, of the Canadian Survey, in 

 a pajjer of wide scope, under the title of " The glaciation of North 

 Central Canada," gave the result of his prolonged researches in 

 the barren lands west of Pludson's Bay. He concluded that the 

 glaciation of these great plains has been effected by ice radiating 

 at different times from three centres of glaciation : the Cordilleran 

 in the west, the Keewatin in the middle region, and the 

 Laurentide or Labradorian in the east, and that there has 

 been throughout the Glacial Period a progressive shifting west- 

 ward of the centres of maximum glaciation. He found no 

 vidence to denote any extensive pre-glacial elevation of the 

 : 1 gion. Mr. Tyrrell's observations cannot fail to modify con- 



r aiderably some existing views as to the cause and growth of ice- 



sheets. Mr. Bailey Willis, in his paper on the drift-phenomena 

 of Puget Sound, and their interpretation, held that the hollows 

 now occupied by the sea in that region were the casts of glaciers, 

 and not, as has been supposed, the effects of submergence. Mr. 

 R. Chalmers sent a contribution on the pre-glacial decay of rocks 

 in Eastern Canada, in which were described the thick sheets of 

 decomposed rock, of Tertiary age, which occur in sheltered 

 positions where they have not been removed by glaciation. 



Three papers dealing with European glacial geology, which 

 were also read on Friday, afforded a clear indication of the 

 similarity of the phenomena on the opposite sides of the At- 

 lantic. Prof. A. Penck, in a general description of the glacial 

 deposits of the Alps, compared their glaciation with that of 



NO. 1455, VOL. 56] 



British Columbia and Alaska, the glaciers pouring down the 

 valleys to form Piedmont ice-lobes terminated by moraines. He 

 thought that two inter-glacial epochs were indicated, each of 

 i much longer duration than post-glacial time, the proportions 

 j being stated as 1:4:6. Assuming the post-glacial period to 

 ' have extended over 20,000 years, he conjectured that the two 

 . inter-glacial periods together occupied 200,000 years, and, 

 I from the evidence of the Poe Plain, that the entire glacial and 

 j inter-glacial periods lasted 500,000 years. While favouring 

 I Richthofen's eolian theory for the loess, he considered that the 

 material had been originally derived from fluvio-glacial deposits. 

 1 He recognised a slight folding of the older glacial strata, and 

 ' held that the lakes, which all lay within the limits of the last 

 j glaciation, were deformed valleys deepened and widened by the 

 ice-sheet and dammed by its moraines. He noted that there 

 were abundant evidences for the existence of man during the last 

 inter-glacial and glacial epoch ; man's antiquity in Europe, there- 

 fore, being about 150,000 years. 



Prince Kropotkin prefaced his paper on the Asar of Finland 



by explaining that his observations were made in 187 1, and that 



! the reason for his long delay was that in running away from his 



i fortress- prison at St. Petersburg, he had to leave his MSS. be- 



1 hind, and had only lately recovered them through the good 



! offices of the Russian Geographical Society. He demurred 



j from the prevalent view that the Asar have been formed in 



: fluvio-glacial rivers, as he had in several instances found that 



j they enclosed a hidden core of true morainic material. 



{ Mr. H. B. Woodward's paper, on the chalky boulder 



clay and the glacial phenomena of the west-midland Counties 



of England, brought clearly forward the similarity of these 



English glacial deposits in their origin with those of North 



America. 



Among the Petrological papers, which were chiefly taken at 



Monday's session, was that of Messrs. Barlow and Ferrier, on 



\ the relation and structures of certain granites and associated 



, arkoses in Lake Temiscaming, Canada, in which they showed 



I that in this region there was a gradual passage from granite to 



i a stratified arkose, as the result of the decomposition and 



dynamic alteration of the former rock. They concluded that 



there has been "a pre-existing basement or floor essentially 



granitic in composition at the base of the Huronian." Prof.. 



W. G. Miller gave a description of some nickelifero.u.s 



magnetites from Eastern Ontario. 



A valuable contribution by Mr. J. J. H. Teall, on differen- 

 tiation in igneous magmas as a result of progressive crystallisa- 

 tion, was read in the absence of the author. Mr. Teall referred" 

 to certain rocks recently collected by the Jackson-Harmsworth 

 expedition in Franz-Josef Land, as proving that magnetite may 

 belong to a very late stage of consolidation, and that progressive 

 crystallisation may lead to a concentration of iron-oxides in the 

 mother-liquor. 



The Palreontological papers were not numerous, perhaps 

 partly because some which might be classed under this head 

 were carried to other sections. A note was read from Sir W. 

 j Dawson, on certain pre-Cambrian and Cambrian fossils sup- 

 posed to be related to Eozoon. Mr. J. F. Whiteaves described 

 a Dendrodont tooth from the Upper Arisaig rocks of Nova 

 Scotia, which he thinks may add a second vertebrate species 

 to the Silurian in Canada. Dr. H. M. Ami had an interesting 

 account of some new or hitherto little-known Palaeozoic 

 formations in North America, in which the author discussed the 

 successive faunas of Ordovician age in New Brunswick and Nova 

 Scotia. An important contribution from Dr. G. F. Matthew 

 was also read by Dr. Ami, on some characteristic genera of the 

 Cambrian, in which the horizon of Olenellns was especially 

 discussed, the conclusion being that its place was above rather 

 than below the Paradoxides beds, and therefore not at the base 

 of the Cambrian system. 



Mr. A. C. Seward's paper, on the possible identity oi Bennet- 

 tites, VVilliamsonia and Zamites gigas, explained with the aid. 

 of lantern illustrations, completes the Palteontological list. 



On Tuesday, among other papers. Dr. E. W. Claypole gave 

 a comprehensive account of the Palaeozoic geography of the 

 Eastern States, illustrating by lantern slides the chief geo- 

 graphical and hydrographical changes of the mid-Pala'Ozoic era. 

 in that region. 



Space forbids notice of the various Committees of Research, 

 though several of these were of considerable interest, notably 

 that on the secondary fossils of Moreseat, Aberdeenshire, by 

 J. Milne and A. J- Jukes-Browne ; that on erratic blocks, by 



