476 ME. F. W. HARIvLEit ON THE [Aug. IQOI, 



have caused, in former times, seasons milder in Greenland, and more 

 severe in one part or another of Europe.^ 



While cordially acknowledging the great interest and value of the 

 theories of Prof. Chamberlin and Dr. Ekholm, especially as applied 

 to the more important changes of climate daring past epochs, I am 

 still inclined to think that the minor variations of the Pleistocene, 

 the prehistoric, and the historic periods may have belonged to 

 one great series of events, and have been alike due to the cause 

 which gives Great Britain its variable seasons at the present day, 

 namely, to alterations in the direction of the prevalent 

 winds. 



Discussion . 



Sir Henry Howoeth commented on the difficulty of discussing a 

 meteorological paper at the Geological Society. He found himself 

 unable to agree either with the Author's premisses or his conclusions. 

 The Author, for instance, took the ice-sheet for granted. It was by 

 no means clear whether he attributed his Pleistocene winds to the 

 ice-sheet or his ice-sheet to the Pleistocene winds. He wished to 

 know how the Author proposed to increase the evaporation of the 

 temperate regions so as to secure a sufficient snowfall for his ice- 

 sheet, and having got his requisite moisture, how was he going to 

 increase the cold of summer sufficiently to prevent the winter's snow 

 from being melted every year ? The speaker believed that at present 

 a fortnight or three weeks was sufficient to denude all snow- covered 

 surfaces of their winter snowfall, except mountain-tops and some 

 parts of the Arctic lands. The theory that the periods of glaciation 

 of North America and Europe alternated was contrary to the 

 generally expressed opinions of glacialists. The arguments founded 

 on the Sahara and North-eastern Asia seemed equally at fault ; and 

 the more he tested the paper, the less he could find in it to agree 

 with. 



Prof. SoLLAS remarked that, if the conclusions to which the Author 

 had been led might for the present be regarded as matters of con- 

 troversy, there could at all events be no doubt as to the value of his 

 methods. The Author had the honour of being the first to treat 

 questions of ancient climate by the exact charting of Dr. Buchan, and 

 this was likely to give greater definiteness to our discussions. One 

 of the most important deductions to which the Author had been 

 led, was that glacial conditions had alternated in the two hemi- 

 spheres. It was to be hoped that it might be found possible to test 

 this result by observation ; but the extensive glaciation which had 

 been found on high land within a few degrees both north and south 

 of the Equator, and as well in the Old World as in the New, seemed 

 to suggest some very general cause for the conditions of the Glacial 

 Period ; and if so, this might have operated in other ways than 

 those considered by the Author. At present Greenland and Norway, 



^ See also T. C. Chamberlin, Journ. Geol. Chicago, vol. vii (1899) p. 770. 





