and Deposits of Flooded Rivers, 45 



and Griimell Land 1,000 to 2,000 feet. Again, in British 

 Columbia and the Queen Charlotte Islands, Dr. Dawson and 

 others find proofs of submergence, ranging up to 200 or 300 

 feet, while the glacial conditions still endured. 



Northwestern Europe, also, had a much greater altitude 

 during the later part of the Tertiary era, in which Scandinavia 

 and the British Isles suffered vast denudation, with erosion of 

 fiords and channels that are now submerged 500 to 800 feet 

 beneath the sea. The maximum preglacial elevation probably 

 exceeded the depth of the Skager Hack between Denmark and 

 Norway, which is 2,580 feet, with a deep submerged valley 

 running from it west and north to the abyssal Arctic ocean.* 

 Under the weight of its ice-sheet, the glaciated area of Europe, 

 like that of North American, sank mostly to a somewhat lower 

 level than it now has, the maximum depression in Scotland, 

 Sweden and Norway, and Spitzbergen, being 500 to 580 feet.f 

 From this depression Scandinavia has gradually risen, with 

 pauses, during which beaches were formed ; and the uplift of 

 that peninsula, as of the. country about Hudson bay, continues 

 to the present day.J 



The climatic conditions of the Ice age were very favorable 

 for the production of river floods. During the times of great 

 continental elevation and the accumulation of ice-sheets, the 

 highlands and mountains south of the glaciated areas received 

 in the winters far more snowfall than now, and in the summers 

 this was melted fast, giving the streams far greater volume 

 during their stages of flood than at the present time. The 

 approximate parallelism of the southern boundary of the ice- 

 sheets with the present isothermal lines and with belts of 

 equal precipitation of rain and snow, indicates that the distri- 

 bution of heat and the courses of storms were somewhat the 

 same as now. It seems to be proved, however, by the abun- 

 dant occurrence of Pleistocene fossils on the isthmus of Pan- 

 ama, " all living up to the present time," collected by Dr. G. 

 A. Maack up to the height of 763 feet,§ that the lower portions 

 of this isthmus were submerged once, or perhaps repeatedly, 

 during the Glacial period, permitting the warm equatorial 

 current of the Atlantic to continue right onward into the 

 Pacific ocean, instead of flowing northeastward out of the 

 Gulf of Mexico. A large amount of warmth would thus be 

 withdrawn from the northern Atlantic area. It is also prob- 

 able that the part of the bed of the North Atlantic stretching 



* Nature, vol. xxiii, p. 393, with map of submarine contour. 



f Am. Geologist, vol. ii, pp. 375-6, Dec. 1888. Geol. Mag., Ill, vol. vi, 1889, 

 pp. 157-8. Nature, vol. xv, p. 123, and vol. xxxii, p. 555. 



% Nature, as last cited, and vol. xxxix, pp. 488-492. 



§ Reports of Explorations for a Ship Canal, Isthmus of Darien, Navy Depart- 

 ment, Washington, 1874, pp. 155-175. 



