376 ON THE PHYSICAL GEOLOGY OF THE UPPER PUNJAB, 



Discussion. 



Prof. Ramsay was glad to find that the author endorsed his view 

 of the recurrence of glacial epochs, which had now been advancing 

 for several years. Prom South Africa there was evidence of a gla- 

 cial epoch of early date, in the form of great boulder-beds lying on 

 roches moutonnees, the origin of which could be traced more than 

 100 miles away into existing mountains. He thought that the 

 average climates of the world had not greatly changed since the 

 Silurian period. 



Prof. T. Rupekt Jones remarked that Dr. Fleming had, many 

 years ago, published a notice of this district in the Society's ' Jour- 

 nal/ and that he believed some of the specimens were still in the 

 Museum of the Society. 



Prof. W. Boyd Dawkins said that although scratched boulders might 

 prove the action of ice, the requisite climatal conditions might be 

 attained by increased elevation of the land above the sea, so that they 

 could furnish no proof of the occurrence of a so-called glacial period. 

 He thought, for example, that in the Miocene period, if there had 

 been a glacial period in Europe, it ought to have made itself felt in 

 the fauna and flora ; yet both these were tropical. The fossils of 

 the Siwaliks were abundant, and included an immeuse number of 

 vertebrates, but none that showed any thing of a northern type. 

 Hence he thought that the scratched blocks might perfectly well 

 have been produced by local elevations of the land. 



Prof. Seeley agreed with Prof. Dawkins that for the production 

 of what were regarded as the phenomena of a glacial period, nothing 

 more than increased elevation was required ; thus in the Permian, 

 for example, the land might well have been elevated into mountain- 

 chains, and thus glaciers appeared. Even at the present day, with 

 glaciers on the Himalayas, there were tropical plants at no great 

 distance on the plains below. 



Mr. Johnston-Lavis wished to ask, if one hemisphere was in a 

 glacial condition, where would the tropics and equator be situated, 

 seeing that Prof. Ramsay said that he did not believe there had been 

 much change in climate since Silurian times ? 



Prof. Ramsay explained that he did not use the term " glacial 

 epoch" as equivalent to Lower Silurian, or Devonian, or Miocene; 

 in fact it was rather a glacial episode than an epoch. He held the 

 same opinion as Dr. Croll, that when there was a glacial epoch in 

 the northern hemisphere there would be the reverse in the 

 southern. 



Mr. Usshepv inquired whether an unconformity existed below the 

 Triassic group. 



Dr. Oldham said there was conformity all through the series in 

 the district described by the author, but that unconformity occurred 

 in other districts. 



