Geological Society of London. 329 



Prof. Hughes thouglit that the theory of ice-caps spreading in both hemispheres 

 from the poles to near the equator hardly deserved discussion, seeing that no facts 

 which could not be otherwise explained had been adduced in support of it, whilst it 

 involved great physical difficulties, and was quite inconsistent with the continuity of 

 the forms of life from pre- to postglacial times. The question before them seemed 

 to be whether a smaller general drifting from northern circumpolar regions, either of 

 land- or floating-ice, would better account for the phenomena observed by the author 

 than a dispersion of boulder- bearing ice in all directions from local centres, especially in 

 the case before them from North Scandinavia. He always understood that the borders 

 of N. Germany and W. Russia could be traced to that mountain-district, and that 

 there was proof that the ice travelled to the north as well as to the south. Unless, 

 therefore, the author showed that some of the boulders could have been derived only 

 from circumpolar regions, he could not see the necessity of calling in anything more 

 than changes of level of various parts of the northern hemisphere along well-known 

 lines of elevation and depression to explain all the phenomena observed. He ques- 

 tioned the accuracy of the view that glacial conditions prevailed at the same time 

 over the whole of even one hemisphere ; and referring to the observations of Mr. 

 Drew, pointed out that if the glaciers of any mountain-region were shown to have 

 once descended 3000 to 6000 feet lower than the present ice-foot, it was only necessary 

 to raise that chain 3000 to 6000 feet to make the glaciers descend to their ancient 

 level again. 



Mr. Whitaker thought that the broad points of the paper had been lost sight of. 

 The rounded configuration of rocks in Norway he regarded as clearly of glacial origin, 

 but as the efi'ect rather of a great extension of glaciers than of a true polar ice-cap. 

 In Britain the glacial drift towards its southern limit is almost wholly marine, and 

 certainly not due to the action of land-ice, so that it is distinctly opposed to the notion 

 of the southern extension of the ice-cap. He could not believe in the existence of 

 such a cap extending as far as the equator. 



Mr. Topley thought that Mr. Campbell's views as to permanent areas of glaciation 

 and non-glaciation due to cold and warm currents did not sufl&ce to explain the facts ; 

 nor did he think that a warm current could have passed over the plains of Russia. 

 He remarked that there is no drift in the South of Europe, and that a line running 

 nearly in the latitude of Dover would mark the southern limit of the drift. 



Mr. Prestwich said that he admired Mr. Campbell's paper, and recognized that the 

 difficulty in this case lay in determining the boundary between the action of land- and 

 sea-ice. He thought that the existence of a Gulf-stream traversing Eastern Europe 

 was not proved. In the eastern counties of Great Britain there is evidence of sub- 

 mergence in Glacial times, and marine drifts also exist in Brittany. If Northern 

 France were submerged, ingress might be afforded to warmer water. 



Mr. Blanford considered that the difference in the faunas of the Black Sea and of 

 the Caspian was so great as to furnish a strong objection to there having been a 

 branch of the Gulf-stream passing on towards Siberia at so late a geological period, 

 as this must have brought about a closer resemblance between the faunas. He 

 objected to blocks found at a considerable distance from mountains being regarded 

 as true ice-borne boulders unless they were striated or polished, seeing that blocks 

 three or four feet in diameter might be seen in Persia, which had been carried five 

 miles or more by the water of insignificant sti-eams. In Persia the country, although 

 greatly elevated above the sea-level, is covered with drift, but there are no signs of 

 striation on the pebbles. In Central Asia, again, long ranges of from 5000 to 6000 

 feet high show no glacial markings. In his opinion the ice-sheets were entirely local. 



The President remarked that the question of glaciation has always been a puzzle. 

 He thought that the notion of great ice-caps covering the northern and southern 

 hemispheres could not be maintained, since it involved the destruction and new 

 creation of the entire fauna and flora. If the boulders referred to by Mr. Campbell 

 were of northern origin, there must have been a flow of water from north to south. 

 It seemed to him difficult to conceive how a current from the Atlantic could have 

 passed over the high lands of Greece. He thought the question as to the glaciation 

 of the Caucasus of much interest. It is difficult to conceive how so vast a denudation 

 as that described could have occm-red without either heavy rains or glaciers, but no 

 rains occur there at present. An alteration of level would affect the temperature. 



Mr. Campbell, in reply, stated that he had seen it given as Prof. Agassiz's opinion 

 that the ice-caps had extinguished all life. He remarked that the boulders have 

 travelled at least 500 miles from their original bed over level ground. 



