Page:Quarterly Journal of the Geological Society of London, vol. 33.djvu/111

Rh AUSTRALIAN CAINOZOIC (TERTIARY) DEPOSITS. 73 would be sufficient to account for these changes of climate on the surface of the globe. Prof. Ramsay could not agree with the last speaker in thinking that radiation in cooling would produce any palpable effect on the surface of the globe. So far from there being any proof that the climate. had been gradually growing colder from the earliest times down to the present date, there was every evidence to show that glacial periods had recurred at different periods in past time. Dr. Duncan and Mr. Evans had merely given suggestions, but had not solved the problem and proved that the poles did not occupy the same position in Miocene times that they do today. Darwin and Dana were both agreed in thinking the present continents to be of extreme antiquity. Great elevations of land had taken place prior to the Miocene epoch. The Alps and the Himalayas were both pre-Miocene, and were probably higher in pre-Miocene times than at present, having been subjected to great denudation. Mr. Gwyn Jeffreys pointed out that certain species of shallow- water mollusca now found in the Arctic Ocean had formerly in post- Tertiary times lived as far south as Sicily. Dr. Wright remarked that there was a wonderful similarity be- tween the Miocene echinoderms from Australia and those found at Malta. Prof. Morris considered the abundance of Echinoderms belonging to the Spatangoid group in these Australian beds to be very interest- ing. The feature presents itself in the New-Zealand Tertiaries, where forms allied to Arachnoides occur. The distribution of these Echinoderms in New Zealand was excessively complex and difficult to understand. There was a remarkable similarity between the Miocene floras of Greenland and Central Europe ; and the question to be asked was, Did they spread over a continent formerly existing between these points, or had they emigrated from some one central spot ? Dr. DtnsrcAN-, in reply, stated that it was only by the united inves- tigations of all students of geology that the question could be in any way settled. The belief in the recurrence of glacial epochs was founded on some erroneous conclusions drawn from beds in South Africa, which were really nothing more than a volcanic dj^ke, and from some deposits in India at the base of the Himalayas. The Miocene plants could not have existed without sufficient light, and therefore could not have extended so far north under conditions si- milar to the present. The Echinoderms did certainly present a striking resemblance to those found in the Miocene beds of Malta ; but there were still sufficient specific differences to justify him in describing them as distinct.