194 W. UPHAM — PLEISTOCENE AXI> PRESENT ICE-SHEETS. 



about 14 miles from the head of Ameralik fjord and 70 miles from the 

 outer coast line. For the first 15 miles in the ascent from the east, rising 

 to the altitude of 1,000 meters, or 3,280 feet, the average gradient was 

 nearly 220 feet per mile. In the next o5 miles an altitude of 2,000 meters, 

 or 6,560 feet, was reached; and the average gradient in this distance, be- 

 tween 15 and 50 miles from the margin of the ice, was thus about 94 

 feet per mile, or a slope very slightly exceeding one degree. The highest 

 part of the ice-sheet, about 112 miles from the point of starting, was 

 found to have an altitude of 2,718 meters, or about 8,920 feet. Its ascend- 

 ing slope, therefore, in the distance from 50 to 112 miles was about 38 

 feet per mile. Thence descending westward, the gradients are less steep, 

 averaging about 25 feet per mile for nearly 100 miles to the altitude of 

 2,000 meters, about 63 feet per mile for the next 52 miles of distance and 

 1,000 meters of descent, and about 125 feet per mile for the lower western 

 border of the ice* 



But Greenland has not always been thus ice-enveloped. During the 

 middle or earlier portions of the Tertiary era forest trees belonging to a 

 temperate flora extended northward in western Greenland to the Arctic 

 circle. Going much farther back to inquire the origin of this great island, 

 we find that it is an outlier of the North American plateau of Archaean 

 rocks, which comprises also Ellesmere land, the eastern part of North 

 Devon, Baffin land, Labrador and the country around Hudson bay, 

 stretching thence southwestward to lakes Huron, Superior and Winnipeg, 

 and westward to Athabasca, Great Slave and Great Bear lakes, and to 

 Coronation gulf of the Arctic sea. The greater part of the Arctic archi- 

 pelago, however, consists of Paleozoic strata. During long Mesozoic and 

 Tertiary ages of higher altitude of these regions subaerial stream erosion 

 formed the channels which divide the Arctic islands, the basin and valley 

 of Hudson bay and strait and those of Baffin bay and Davis strait, which 

 now by subsidence separate Greenland from the mainland. More ample 

 oceanic circulation, carrying warmth from tropical and temperate latitudes 

 to the Arctic sea, was probably the cause of the formerly luxuriant vegeta- 

 tion of Greenland ; but during the ensuing Pleistocene period its ice-sheet 

 was for some time even more extended and deeper than now, as is shown 

 by the glaciation of the rock surface high up on the sides of the fjords. 



The Malaspinet, Glacier or Ice-sheet. — The comparatively small Malaspina 

 ice-sheet, stretching from the Saint Elias range to the shore of the Pacific 

 ocean, has been described as follows by its principal explorer, Professor 

 I. C. Russell, after his two expeditions of 1890 and 1891 : f 



*The First Crossing of Greenland, 2 vols., 1890. 



f" Mount Saint Elias and its Glaciers," Am. .lour. Sci., III, vol. xliii, pp. 169-182, with map, March, 

 1892. The report of the first expedition, in 1890, is given by Russell in the National Geographic 

 Blagazine, vol. iii, pp. 53-203, with 19 plates, and < s figures in the text, May 29, 1891. 



