. Elements of geology : a text-book for colleges and for the general reader. Geology. 70 AQUEOUS AGENCIES. Floating Ice—Icebergs. We have already seen (page 50) that at a certain latitude, varying from 46° in South America to about 65° in Norway, glaciers touch the surface of the ocean. Beyond this latitude, they run out to sea often to great distances. By the buoyant power of water, assisted by tides and waves, these projecting floating masses are broken off, and accumulate as immense ice-barriers in polar seas, or are drifted away by currents toward the equator. Such floating fragments of gl
. Elements of geology : a text-book for colleges and for the general reader. Geology. 70 AQUEOUS AGENCIES. Floating Ice—Icebergs. We have already seen (page 50) that at a certain latitude, varying from 46° in South America to about 65° in Norway, glaciers touch the surface of the ocean. Beyond this latitude, they run out to sea often to great distances. By the buoyant power of water, assisted by tides and waves, these projecting floating masses are broken off, and accumulate as immense ice-barriers in polar seas, or are drifted away by currents toward the equator. Such floating fragments of glaciers are called ice- bergs. Fig. 65 is an ideal section, through a glacial valley, in which a g is the glacier, b the cliffs beyond, I s' the sea-level, and i an Formation of Icebergs. The principal source of the icebergs of the north Atlantic is the coast of Greenland. This country is an elevated table-land, sloping in every direction to a coast deeply indented like Norway, with alter- nate deep fiords and jutting headlands. The whole table-land is com- pletely covered with an ice-sheet, probably several thousand feet thick, moving slowly seaward, and discharging through the fiords as immense glaciers,* which, as already explained, form icebergs. In this remarka- ble country no water falls from the atmosphere except in the form of snow, and all the rivers are glaciers. The geological effects of such a moving ice-sheet may be easily imagined. The whole surface of the country rock must be polished and scored, the general direction of the striae being parallel over large areas. The antarctic continent is probably similarly, and even more thick- ly, ice-sheeted, for the humid atmosphere of that region is very favorable to the accumulation of snow and ice. Captain Wilkes found an impen- etrable ice-barrier, in many places 150 to 200 feet high, for 1,200 miles along that coast. From this ice-barrier, icebergs separate and are drifted toward the equator. * Dr. Rink, A
Size: 2228px × 1122px
Photo credit: © Paul Fearn / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1890, booksubjectgeology, bookyear1892
