Geological Society of London, 325 



of clouds, winds, and aqueous vapour, is sufficient to account for tlie 

 former prevalence of temperate climates in the Arctic regions, and 

 this view, the author stated, he had himself been contending for for 

 more than twelve years. He thinks, however, that alterations in the 

 excentricity of the earth's orbit is the primary motive cause, whilst 

 Sir William Thomson believes this to be the submergence of circum- 

 polar lands, which, however, in Miocene times, appear to have been 

 more extensive than at present. He pointed out that a preponderance 

 of equatorial land, as assumed by Sir Charles Lyell to account for 

 the milder climate of Arctic regions in Miocene times, would rather 

 tend to loss of heat by rapid radiation into space, whilst water is re- 

 markably powerful as a transporter of heat, so that, in this case, 

 equatorial water rather than equatorial land is needed. 



In speaking of the glacial climate, the author maintained that 

 local causes are insufficient to explain so extensive a phenomenon. 

 He indicated that we are only too prone to seek for great or cata- 

 clysmic causes, and although this tendency has disappeared from 

 manj' fields of geological research, this is not the case in all. His 

 explanation of the causes of a mild climate in high northern latitudes 

 is as follows :— Great excentricity of the earth's orbit, winter in 

 perihelion, the blowing of the south-east trades across the equator 

 perhaps as far as the tropic of Cancer, and impulsion of all the 

 great equatorial currents into northern latitudes ; on the other hand, 

 when, with great excentricity, the winter is in aphelion, the whole 

 condition of things is reversed ; the north-east trades blow over into 

 the southern hemisphere, carrying with, them the great equatorial 

 currents, and glacial conditions prevail in the northern hemisphere. 

 Thus those w^arm and cold periods which have prevailed during 

 past geological ages are regarded by the author as great secular 

 summers and winters. 



3. " On the Distribution of Ice during the Glacial Period." By 

 T. r. Jamieson, Esq., F.G.S. 



The author believes that a study of the distribution of ice during 

 the Glacial period proves that the greatest accumulations of snow 

 took place in precisely those districts which are now characterized 

 by a very heavy rainfall, and he pointed out how exactly this is in 

 accordance with the views of Prof. Tyndall as to the conditions most 

 favourable to the development of glaciers. In support of this con- 

 clusion he reviewed the phenomena presented by the most highly 

 glaciated districts of the British Islands, of Scandinavia, and Europe 

 generally, and of Asia and North America, and contended that in 

 every case his opinion is borne out, the districts which are now re- 

 markable for an excessive rainfall having been formerly centres of 

 dispersion for great systems of glaciers. The notion of a polar ice- 

 cap he held to be opposed to many well-known facts ; and he dis- 

 cussed the distribution of various forms of life during and since the 

 Glacial epoch, with the object of determining whether the drainage 

 of ice from the great polar basin was effected by means of the de- 

 pression of Davis's Straits or of Behring's Straits. The evidence 

 appeared to him to be in favour of the former channel. 



