TRANSACTIONS OF SECTION C. 803 
6. Report on Erratic Blocks.—See Reports, p. 366. 
7. Another Possible Cause of the Glacial Epoch. 
By Professor Epwarp Hutt, LL.D., F.R.S., F.G.LS. 
The author gave an account of the results arrived at by Professor J. W. 
Spencer, Ph.D.,in his memoir on ‘ The Reconstruction of the Antillean Continent’ 
(‘Bull. Geol. Soc.,’ America, January 1895) from observations laid down on the 
Admiralty charts of the east coast of North America and the shores of the West 
Indian Islands and Gulf of Mexico. He shows that the ‘continental shelf’ lying 
between the coast and the 100-fathom line is succeeded by a second and deeper 
plateau, called by Professor A. Agassiz ‘the Blake plateau,’ the average depth of 
which may be taken at 2,700 feet, separated from the continental shelf by a steep 
descent, and in its turn bounded by a second steep descent leading down to the 
abysmal depths of the Atlantic Ocean at 12,000 or 13,000 feet below the surface. 
A careful investigation of the soundings shows that these plateaus 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 con- 
nected with the outer margins of the plateaus by wide embayments. The form of 
these channels would in some cases entitle them to be called ‘ cafions’ 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 embayments where they open out on 
the floor of the ocean. Such an elevation of 12,000 feet or so would have con- 
nected North and South America along the line of the Antilles, constituting a 
angle continent,' and are termed ‘ stupendous changes of level’ of the Pleistocene 
epoch. 
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 Antillean 
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 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 Stream 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 
30° F. (the freezing point of water) to those of the 42° F. of the present day, 
resulting in sub-glacial conditions along the line of this isotherm. 
Proceeding next to examine the effects of the elevation of the American con~ 
tinent to the extent required by Professor Spencer’s conclusions, the author 
considers it as extremely 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. 
8. Final Report on the High-level Shell-bearing Deposits at Clava 
and Kintyre.—See Reports, p. 378. : 
? 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, will probably suffice. 
