September 12, 1884." 



SCIENCE. 



259 



North American continent. He pointed out the evi- 

 dences of a genial climate at the close of the miocene 

 and pliocene, which were soon followed by the age of 

 ice ; traced the southern limit of the ice-sheet across 

 the continent as far as it has been observed, and ex- 

 pressed his belief in two glacial periods. 



These papers were discussed together. Professor 

 James Geikie was niiable to draw any sharp line 

 separating moraines and kames, for they merge into 

 each other in such a manner that one cannot say 

 where one leaves off and the other begins. Kames 

 he regarded as partly morainic, and partly of subgla- 

 cial origin ; and he was in accord with Dr. Newberry in 

 regard to the break in the glacial period. Sir William 

 Dawson was inclined to think that water was largely 

 instrumental in producing the work attributed to ice, 

 and referred to the evidences in eastern North Amer- 

 ica, of the warm interval during the ice age. Dr. 

 Selwyn briefly proposed a possible explanation of the 

 supposed power of ice to excavate, in solid rocks, 

 basins like those of the great lakes. He referred to 

 the profound decomposition of rocks observed in 

 Australia and in the gneiss of Brazil. In Australia 

 this decomposition was sometimes two hundred and 

 fifty feet deep; and he thought it possible that ice, 

 entering such a region, would be able to make such 

 basins as those of the great lakes. Professor Spencer, 

 of the university of Missouri, contributed some of 

 the results of his own work upon the subject of the 

 origin of the basin of Lake Ontario, which led him 

 to believe that this lake basin, at least, was not of 

 glacial origin. Professor Hall of New York called 

 attention to the fact that the axes of the lakes are 

 along the lines of outcrop of the rocks, and that the 

 basins are excavated in the softer material. 



Four other contributions, relating in one way or 

 another to the glacial period, were read without 

 much discussion; and the theories concerning the 

 causes of the ice age were taken up. The Eev. Mr. 

 Hill classed the theories as cosmical, terrestrial, and 

 astronomical. The first class was not regarded as 

 worthy of consideration, while terrestrial theories 

 were as readily disposed of as being more or less un- 

 satisfactory. Attention was directed especially to the 

 theory of Dr. Croll, a combination of the precession 

 and eccentricity theories. It was held that the part 

 of CrolPs explanations regarding fogs, deflection of 

 currents, and the like, would support any or all 

 theories alike. His conclusion was, that the altera- 

 tion of currents and winds seemed to be the most 

 powerful causes thus far suggested. 



That part of Croll' s theory regarding the greater 

 eccentricity of the earth's orbit was attacked by Mr. 

 W. F. Stanley in another paper. He could not con- 

 ceive of the earth's initial temperature having been 

 lower, or of the sun's heating power being less, and 

 that therefore glaciation could not have depended 

 upon such conditions. He regarded it as a local phe- 

 nomenon, due to aerial and oceanic currents. 



There was no session on the 30th, the day being 

 given over to excursions. To the English geologists 

 the occasion was a welcome one; and under the guid- 

 ance of members of the geological survey of Can- 



ada, and of the local committee, they visited Ottawa, 

 Ausable Chasm, Lake Memphremagog, Quebec, and 

 various localities in the immediate vicinity of Mont- 

 real. . 



The prominent questions coming before the section 

 on the 1st were those regarding archaean rocks. 

 Professor Bonney opened the question with a lengthy 

 paper upon these rocks in England, and made some 

 comparisons with those of Canada. Dr. T. Sterry 

 Hunt followed, treating of the eozoic rocks of North 

 America. The paper was a resume of some of Dr. 

 Hunt's old work. As might have been expected, the 

 very use of the word * eozoic ' was followed by some 

 shaking of the head among the members; and, at the 

 close of Dr. Hunt's reading, the use of the word was 

 criticised as taking for granted a question which is 

 still in dispute. The writer held, however, that his 

 use of the word did not depend solely upon whether 

 the supposed Eozoon canadense were the remains of 

 a living organism, but upon the evidences of organic 

 life having come into existence at or about the geolo- 

 gical age referred to. 



Professor Hall discussed the question at some 

 length, and expressed the conviction that the solution 

 of the problem lay in the study, not of large masses 

 of rock, but in the study of junctures. 



Every one was interested to hear what Sir William 

 Dawson would say upon this question. He appeared 

 to speak with some hesitation, due doubtless to the 

 opposition to his well-known theories. He had but 

 little to say ; urging as a reason, that he was but poorly 

 qualified to discuss the question from the standpoint 

 from which it was being viewed, — namely, that of a 

 chemical geologist. He said that he had spent his 

 time in trying to find fossils in these rocks, and had 

 got but little thanks for his labor. He would not 

 enter the question in regard to Eozoon here. A 

 co-laborer has the whole matter in hand now, and 

 will soon publish all that is known. Major Powell 

 was called upon, but limited himself to saying that 

 we were not much disturbed by the question in the 

 States, but were limiting ourselves to mapping the 

 regions covered by these archean rocks. 



The paper by Prof. J. D. Dana upon the southward 

 ending of a great synclinal in the Taconic range was 

 read by Professor Brewer, and elicited some very 

 heated and severe protests on the part of Dr. Hunt. 

 He insisted that the structure referred to was known 

 twenty years ago, that the metamorphosis of sedi- 

 mentary beds assumed by Professor Dana was unten- 

 able, and that there was no vestige of a proof of such 

 a thing. Professor Brewer replied in behalf of Pro- 

 fessor Dana, that recent and thorough work had been 

 done in the region referred to, and that nothing was 

 stated upon assumption. Major Powell was astounded 

 that Dr. Hunt should speak as he did, if the structure 

 was as represented ; and he called upon him to either 

 give his reasons for such statements, or to retract 

 them, for the only way to attack such a question was 

 to attack the structure. Professor Hall opposed Dr. 

 Hunt's position, and vouched for the structure as rep- 

 resented; and Dr. Selwyn spoke of the existence in 

 British Columbia of crystalline rocks in the carbon- 



