E. P. Culvericell— Theory of the Ice Age. U 



ocean currents, the winter temperature is much higher than we 

 should anticipate if we neglected every consideration save the winter 

 sun-heat received ; but we must make our selection of instances in 

 a fairer way than by taking any one of these groups. 



No doubt direct sun-heat falling on ice or snow is not a very 

 powerful factor in giving rise to a thaw. Even in these climates 

 we may verify that observation. Often there are bright crisp days 

 with a northerly wind after a fall of snow, and though we may enjoy 

 the warmth of the sunshine, the snow lies on the ground apparently 

 unaffected by it. But soon comes a southerly wind, on a raw misty 

 day, which feels perhaps far colder to us, and a sudden thaw sets in. 

 The snow, which has been hard, becomes soft and sloppy, and_ finally 

 disappears with wonderful rapidity, as often during the night as 

 during the day. From this we learn that though sun-heat falling 

 directty on ice or snow may have but little effect in melting it, yet 

 it is a most effective agent if first applied to warm the land or sea 

 elsewhere, and thus indirectly to warm the air passing over it, which 

 air afterwards passes over the snow. 



What we see on a small scale here is displayed on a vast scale in 

 the sudden thawing of the great river basins which empty into the 

 North Polar Sea. Mr. Henry Seebohm, in his " Siberia in Asia," 

 describes how suddenly the river ice breaks up, and with what 

 almost inconceivable rapidity the snow thaws over a vast extent 

 of country when the south wind sets in. In the companion book, 

 "Siberia in Europe," p. 89, he says: "Summer now [10th May] 

 seemed suddenly to have burst upon us in all its strength ; the sun 

 was scorching, the snow in many places melted so rapidly as to be 

 almost impassable." But by far the most striking account is in his 

 Presidential Address to the Geographical Section of the British 

 Association in 1893. Here he speaks of the " great suddenness " 

 with which the snow melts. Again (Report, p. 828) : " The stealthy 

 approach of winter on the confines of the Polar Basin, is in strong 

 contrast to the catastrophe which accompanies the sudden onrush of 

 summer." 



Again, speaking of the coming of summer in the basin of the 

 Yenesei: "During the month of May there were a few signs of 

 the possibility of some mitigation of the rigours of winter. Now 

 and then there was a little rain, but it was always followed by frost. 

 If it thawed one day, it froze the next ; and little or no impression 

 was made on the snow. Between May 16 and 30 ... . migratory 

 flocks of wild geese passed over our winter quarters ; but if they 

 were flying north one day, they were flying south the next, proving 

 beyond doubt that their flight was premature. The geese evidently 

 agreed with us that it ought to be summer ; but it was as clear to 

 the geese as to us that it really was winter. We afterwards learnt 

 that during the last ten days of May a tremendous battle had been 

 raging 600 miles as the crow flies to the southward of our position 

 on th^ Arctic circle. Summer, in league with the sun, had been 

 fighting winter and the north wind all along the line, and had been 

 hopelessly beaten everywhere, as we were witnesses that it had 



