CAUSE OF MILD POLAR CLIMATES. U9 



In a paper read before the Geological Society of 

 Glasgow in February, 1877, Sir William maintains also 

 that an increase in the amount of heat conveyed by 

 ocean-currents to the Arctic regions, combined with 

 the effect of Clouds, Wind, and Aqueous Vapour, is 

 perfectly sufficient to account for the warm and 

 temperate condition of climate which is known to 

 have prevailed in those regions during former epochs. 

 The following quotations will show Sir William's 

 views : — 



"A thousand feet of depression would submerge the 

 continents of Europe, Asia, and America, for thousands of 

 miles from their present northern coast-lines ; and would 

 give instead of the present land-locked, and therefore ice- 

 bound Arctic sea, an open iceless ocean, with only a number 

 of small steep islands to obstruct the free interchange of 

 water between the North Pole and temperate or tropical 

 regions. That the Arctic sea would, in such circumstances, 

 be free from ice quite up to the north pole may be, I think, 

 securely inferred from what, in the present condition of the 

 globe, we know of ice-bound and open seas in the northern 

 hemisphere and of the southern ocean abounding in icebergs, 

 but probably nowhere ice-bound up to the very coast of the 

 circumpolar Antarctic continent, except in more or less land- 

 locked bays 



" Suppose now the sea, unobstructed by land from either 

 pole to temperate or tropical regions, to be iceless at any 

 time, would it continue iceless during the whole of the sun- 

 less polar winter? Yes; we may safely answer. Supposing 

 the depth of the sea to be not less than 50 or 100 fathoms, 

 and judging from what we know for certain of ocean-currents, 

 we may safely say that differences of specific gravity of the 

 water produced by difference of temperature, not reaching 

 anywhere down to the freezing point, would cause enough of 

 circulation of water between the polar and temperate or 

 tropical regions to supply all the heat radiated from the 



