168 Glaciation of Mountains, Etc. — Upham. 
pole. It everywhere terminates in the sea, and, because it is 
lifted up by the ocean and broken into bergs, its margin has 
the form of a vertical wall, along which Sir J. C Ross sailed 
four hundred and fifty miles, finding only one point sufficiently 
low to allow the upper surface of the ice to be seen from the 
masthead. There it was a plain of snowy whiteness, reaching 
as far as the eye could see. 
In Nordenskiold's journey on the ice-sheet of Greenland, to 
the east from Disco bay, he found that its surface rose to a 
hight of about 2,500 feet in a distance of fifty miles ; to 5,200 
feet, or nearly one mile in a hundred and sixty miles ; and to 
6,465 feet in three hundred miles. The average ascent of the 
ice surface in the first fifty miles, including the more rapid 
rise near the margin, is about fifty feet per mile, or slightly 
more than half of one degree ; in the next hundred and ten 
miles it is about twenty-five feet per mile ; and in the remain- 
ing hundred and forty miles, lying near the center of Green- 
land, the ascent is only nine feet per mile. 
On the Antarctic continent (if it be not a group of islands 
united by the ice-sheet) the volcanoes Terror and Erebus, 
seen in eruption by Ross, rise to bights of about 10,000 
and 12,000 feet. The greater part of Greenland has no moun- 
tains of similar hight, and after ascending upon the border of 
the ice-sheet, which is reached at the head of the fiords not far 
back from tjie coast, occasional ridges and hill-tops are found 
rising out of the ice during the first day's journey upon it, 
beyond which there is a slightly undulating expanse of ice 
and snow, appearing in a broad view as level and illimitable 
as the ocean, and bounded only by the encircling smooth 
horizon. The surface of this ice-sheet in its central part has a 
similar altitude with the highest mountain summits of New 
England and New York, and it overtops the most elevated 
points of the land on which it lies. 
Such too was the ice-sheet of the northern United States 
and Canada, whose border covered the northeastern part of the 
Appalachian mountain system, from northern Pennsylvania 
to where the headland of Gaspe projects into the gulf of 
St. Lawrence. Within this area five prominent mountain 
masses deserve special consideration in respect to their glaci- 
ation : namely, Katahdin, the White mountains, the Green 
mountain range, the Adirondack group, and the Catskills. 
