found by Ryder in Scoresby Sound was 300 fathoms, but there are
certainly still greater depths; like the Norwegian fjords they have,
however, probably all of them, a threshold or sill, with shallow
water, near their mouths. A few soundings made outside this
coast seem to indicate that the fjords continue as deep submarine
valleys far out into the sea. On the west coast there are also
many great fjords. One of the best known from earlier days is
the great Godthaab Fjord (or Baals Revier) north of 64° N. Along
the east coast there are many high mountains, exceeding 6000 and
7000 ft. in height. One of the highest peaks hitherto measured is at
Tiningnertok, on the Lindenov Fjord, in 60° 35′ N., which is 7340 ft.
high. At the bottom of Mogens Heinesen Fjord, 62° 30′ N., the
peaks are 6300 ft., and in the region of Umanak, 63° N., they even
exceed 6600 ft. At Umivik, where Nansen began his journey
across the inland ice, the highest peak projecting through the ice-covering
was Gamel’s Nunatak, 6440 ft., in 64° 34′ N. In the
region of Angmagssalik, which is very mountainous, the mountains
rise to 6500 ft., the most prominent peak being Ingolf’s Fjeld, in
66° 20′ N., about 6000 ft., which is seen from far out at sea, and forms
an excellent landmark. This is probably the Blaaserk (i.e. Blue
Sark or blue shirt) of the old Norsemen, their first landmark on
their way from Iceland to the Öster Bygd, the present Julianehaab
district, on the south-west coast of Greenland. A little farther
north the coast is much lower, rising only to heights of 2000 ft.,
and just north of 67° 10′ N. only to 500 ft. or less.[1] The highest
mountains near the inner branches of Scoresby Fjord are about
7000 ft. The Petermann Spitze, near the shore of Franz Josef
Fjord, measured by Payer and found to be 11,000 ft., has hitherto
been considered to be the highest mountain in Greenland, but
according to Nathorst it “is probably only two-thirds as high as
Payer supposed,” perhaps between 8000 and 9000 ft.
Along the west coast of Greenland the mountains are generally not quite so high, but even here peaks of 5000 and 6000 ft. are not uncommon. As a whole the coasts are unusually mountainous, and Greenland forms in this respect an interesting exception, as there is no other known land of such a size so filled along its coasts on all sides with high mountains and deep fjords and valleys.
The Inland Ice.—The whole interior of Greenland is completely covered by the so-called inland ice, an enormous glacier forming a regular shield-shaped expanse of snow and glacier ice, and burying all valleys and mountains far below its surface. Its area is about 715,400 sq. m., and it is by far the greatest glacier of the northern hemisphere. Only occasionally there emerge lofty rocks, isolated but not completely covered by the ice-cap; such rocks are known as nunataks (an Eskimo word). The inland ice rises in the interior to a level of 9000, and in places perhaps 10,000 ft. or more, and descends gradually by extremely gentle slopes towards the coasts or the bottom of the fjords on all sides, discharging a great part of its yearly drainage or surplus of precipitation in the form of icebergs in the fjords, the so-called ice-fjords, which are numerous both on the west and on the east coast. These icebergs float away, and are gradually melted in the sea, the temperature of which is thus lowered by cold stored up in the interior of Greenland. The last remains of these icebergs are met with in the Atlantic south of Newfoundland. The surface of the inland ice forms in a transverse section from the west to the east coast an extremely regular curve, almost approaching an arc of a wide circle, which along Nansen’s route has its highest ridge somewhat nearer the east than the west coast. The same also seems to be the case farther south. The curve shows, however, slight irregularities in the shape of undulations. The angle of the slope decreases gradually from the margin of the inland ice, where it may be 1° or more, towards the interior, where it is 0°. In the interior the surface of the inland ice is composed of dry snow which never melts, and is constantly packed and worked smooth by the winds. It extends as a completely even plain of snow, with long, almost imperceptible, undulations or waves, at a height of 7000 to 10,000 ft., obliterating the features of the underlying land, the mountains and valleys of which are completely interred. Over the deepest valleys of the land in the interior this ice-cap must be at least 6000 or 7000 ft. thick or more. Approaching the coasts from the interior, the snow of the surface gradually changes its structure. At first it becomes more coarse-grained, like the Firn Schnee of the Alps, and is moist by melting during the summer. Nearer the coast, where the melting on the surface is more considerable, the wet snow freezes hard during the winter and is more or less transformed into ice, on the surface of which rivers and lakes are formed, the water of which, however, soon finds its way through crevasses and holes in the ice down to its under surface, and reaches the sea as a sub-glacial river. Near its margin the surface of the inland ice is broken up by numerous large crevasses, formed by the outward motion of the glacier covering the underlying land. The steep ice-walls at the margin of the inland ice show, especially where the motion of the ice is slow, a distinct striation, which indicates the strata of annual precipitation with the intervening thin seams of dust (Nordenskiöld’s kryokonite). This is partly dust blown on to the surface of the ice from the ice-bare coast-land and partly the dust of the atmosphere brought down by the falling snow and accumulated on the surface of the glacier’s covering by the melting during the summer. In the rapidly moving glaciers of the ice-fjords this striation is not distinctly visible, being evidently obliterated by the strong motion of the ice masses.
The ice-cap of Greenland must to some extent be considered as a viscous mass, which, by the vertical pressure in its interior, is pressed outwards and slowly flows towards the coasts, just as a mass of pitch placed on a table and left to itself will in the course of time flow outwards towards all sides. The motion of the outwards-creeping inland ice will naturally be more independent of the configurations of the underlying land in the interior, where its thickness is so enormous, than near the margin where it is thinner. Here the ice converges into the valleys and moves with increasing velocity in the form of glaciers into the fjords, where they break off as icebergs. The drainage of the interior of Greenland is thus partly given off in the solid form of icebergs, partly by the melting of the snow and ice on the surface of the ice-cap, especially near its western margin, and to some slight extent also by the melting produced on its under side by the interior heat of the earth. After Professor Amund Helland had, in July 1875, discovered the amazingly great velocity, up to 64¾ ft. in twenty-four hours, with which the glaciers of Greenland move into the sea, the margin of the inland ice and its glaciers was studied by several expeditions. K. J. V. Steenstrup during several years, Captain Hammer in 1879–1880, Captain Ryder in 1886–1887, Dr Drygalski in 1891–1893,[2] and several American expeditions in later years, all examined the question closely. The highest known velocities of glaciers were measured by Ryder in the Upernivik glacier (in 73° N.), where, between the 13th and 14th of August of 1886, he found a velocity of 125 ft. in twenty-four hours, and an average velocity during several days of 101 ft. (Danish).[3] It was, however, ascertained that there is a great difference between the velocities of the glaciers in winter and in summer. For instance, Ryder found that the Upernivik glacier had an average velocity of only 33 ft. in April 1887. There seem to be periodical oscillations in the extension of the glaciers and the inland ice similar to those that have been observed on the glaciers of the Alps and elsewhere. But these interesting phenomena have not hitherto been subject to systematic observation, and our knowledge of them is therefore uncertain. Numerous glacial marks, however, such as polished striated rocks, moraines, erratic blocks, &c., prove that the whole of Greenland, even the small islands and skerries outside the coast, has once been covered by the inland ice.
Numerous raised beaches and terraces, containing shells of marine mollusca, &c., occur along the whole coast of Greenland, and indicate that the whole of this large island has been raised, or the sea has sunk, in post-glacial times, after the inland ice covered its now ice-bare outskirts. In the north along the shores of Smith Sound these traces of the gradual upheaval of the land, or sinking of the sea, are very marked; but they are also very distinct in the south, although not found so high above sea-level, which seems to show that the upheaval has been greater in the north. In Uvkusigsat Fjord (72° 20′ N.) the highest terrace is 480 ft. above the sea.[4] On Manitsok (65° 30′ N.) the highest raised beach was 360 ft. above the sea.[5] In the Isortok Fjord (67° 11′ N.) the highest raised beach is 380 ft. above sea-level.[6] In the Ameralik Fjord (64° 14′ N.) the highest marine terrace is about 340 ft. above sea-level, and at Ilivertalik (63° 14′ N.), north of Fiskernaes, the highest terrace is about 325 ft. above the sea. At Kakarsuak, near the Björnesund (62° 50′ N.), a terrace is found at 615 ft. above the sea, but it is doubtful whether this is of marine origin.[7] In the Julianehaab district, between 60° and 61° N., the highest marine terraces are found at about 160 ft. above the sea.[8] The highest marine terrace observed in Scoresby Fjord, on the east coast, was 240 ft. above sea-level.[9] There is a common belief that during quite recent times the west and south-west coast, within the Danish possessions, has been sinking. Although there are many indications which may make this probable, none of them can be said to be quite decisive.[10]
[Geology.—So far as made out, the structure of explored Greenland is as follows:
1. Laurentian gneiss forms the greatest mass of the exposed rocks of the country bare of ice. They are found on both sides of Smith Sound, rising to heights of 2000 ft., and underlie the Miocene and Cretaceous rocks of Disco Island, Noursoak Peninsula and the
- ↑ See C. Kruuse in Geografisk Tidskrift, xv. 64 (Copenhagen, 1899). See also F. Nansen, “Die Ostküste Grönlands,” Ergänzungsheft No. 105 zu Petermanns Mitteilungen (Gotha, 1892), p. 55 and pl. iv., sketch No. 11.
- ↑ E. v. Drygalski, Grönland-Expedition der Gesellschaft für Erdkunde zu Berlin, 1891–1893 (2 vols., Berlin, 1897).
- ↑ Meddelelser om Grönland, part viii. pp. 203-270 (Copenhagen, 1889).
- ↑ Ibid. part iv. p. 230 (Copenhagen, 1883); see also part xiv. pp. 317 et seq., 323.
- ↑ Ibid. part xiv. p. 323 (Copenhagen, 1898).
- ↑ Ibid. part ii. pp. 181-188 (Copenhagen, 1881).
- ↑ Ibid. part i. pp. 99-101 (Copenhagen, 1879).
- ↑ Ibid. part ii. p. 39 (Copenhagen, 1881); part xvi. pp. 150-154 (1896).
- ↑ Ibid., part xix. p. 175 (1896).
- ↑ Ibid. part i. p. 34; part ii. p. 40; part xiv. pp. 343-347; part iv. p. 237; part viii. p. 26.
