Notices of Memoirs— Prof. E. Hull— Glacial Epoch. 515 



below the surface. A careful investigation of the soundings shows 

 that these plateaux are traversed by channels, sometimes of great 

 depth and with precipitous sides, leading down from the embouchures 

 of the existing rivers which open out on the coast, and connected 

 with the outer margins of the plateaux by wide emhayments. The 

 form of these channels would in some cases entitle them to he called 

 " canons " or " fjords " ; and as Professor Spencer truly considers 

 that such channels could only be formed by river erosion, he 

 concludes that the whole eastern coast and the West Indian Isles 

 were elevated to the extent of the outer emhayments where they 

 open out on the floor of the ocean. Such an elevation of 12,000 

 feet or so would have connected North and South America along 

 the line of the Antilles, constituting a single continent, and are 

 termed "stupendous changes of level" of the Pleistocene epoch. 1 



The author of this paper proceeds to discuss some of the climatic 

 conditions which would result from such changes, and supposes 

 that the elevation of the Antillosan continent would have shut out 

 the northern branch of the great equatorial current, known as the 

 Gulf Stream, from the Caribbean Sea and the Gulf of Mexico, 

 causing it to enter the North Atlantic directly ; and he comes to 

 the conclusion that the Atlantic current would have crossed the 

 40th parallel with a surface temperature of only 74° F. instead of 

 84° F., as is the case at the present day. The author then discusses 

 the question to what extent such a lowering of the temperature of 

 the present Gulf Sti-eam would have affected the climate of the 

 regions bordering the North Atlantic, and considers that this effect 

 may be approximately arrived at by transferring the climatic 

 conditions of the isotherm of annual mean temperature of 32° F. 

 (the freezing-point of water) to those of the 42° F. of the present 

 day, resulting in suhglacial conditions along the line of this isotherm.'- 



Proceeding next to examine the effects of the elevation of the 

 American continent to the extent required by Professor Spencer's 

 conclusions, the author considers it as extremehy probable that the 

 cold produced by this physical change, added to that due to the 

 lowering of the temperature of the Atlantic current, would result in 

 bringing about the conditions of the Glacial epoch ; and as similar 

 elevation of land has been determined in the case of the platform of 

 the British Isles and North-Western Europe — though to a much 

 smaller extent than in the case of the American continent — the 

 increased cold due to this cause, added to that due to the diminished 

 temperature of the Atlantic current, would have been, if not a vera 

 causa of the Glacial epoch of Europe, a most material cause in 

 bringing about the climatic conditions of that epoch. 



1 For those who are unable to obtain Professor Spencer's original memoir, the 

 review thereof by Mr. A. J. Jukes-Browne, F.G.S., in the Geological Magazine 

 for April, 1895 (p. 173), will probably suffice. 



2 The isotherm of 42° passes by the north coast of the British Isles. 



