the parent glacier, the form of its bed, and the depth of the water at its mouth. The larger fragments originate for the most part along that remarkable break which is presented in the normal formation of the coast-line between Egedesminde and the Svartenhuk Peninsula. Rink enumerates not more than thirty Greenland glaciers which discharge really large icebergs, and of this number only six or eight yield blocks of the first magnitude.

The average velocity of the congealed masses is about fifty feet in the twenty-four hours, but in some places a much greater speed has been recorded, though still varying considerably with the seasons. A branch of the Augpadlartok glacier, north of Upernavik, moves at the rate of one hundred feet a day, the highest yet measured. But how enormous must be the pressure of the inland ice-fields to discharge into the sea the vast quantities of icebergs which are yearly sent adrift along the Greenland seaboard! Estimated in a single block the annual discharge from each of the five best-known glaciers would represent a mass of about seventeen billion cubic feet in capacity, and fifty-six hundred feet in height, depth, and thickness. Reduced to a liquid state this mass would be equivalent to a stream discharging seaward five hundred cubic feet per second, or 15,500,000 a year.

The formation of this drift ice, or floating icebergs, is one of those phenomena which were discussed long before the seaboard had been studied, or before the breaking away of the frozen masses had actually been witnessed. Wherever the glaciers discharge through a broad valley preserving a uniform width and depth for a considerable space, and advancing seaward through a fiord of like dimensions, and with gently sloping bed, the ice may progress without any of those accidents caused by the inequalities of more rugged channels. Under such conditions the compact mass glides smoothly forward over its rocky bed without developing any rents or fissures. But as it moves down like a ship on its keel, it tends to rise, being at least one twentieth lighter than the displaced water. It is also left without support by the sudden fall of its bed beyond the normal coast-line. Nevertheless, it still continues its onward movement through the waters to a point where its weight prevails over its force of cohesion with the frozen stream thrusting it forward. At this point it snaps off suddenly with a tremendous crash, and the iceberg, enveloped in a thousand fragments projected into space, plunges into the abyss and whirls round and round to find its center of gravity amid the troubled waters. On recovering from the bewilderment caused by all this tumult and chaos, the spectator finds that the glacier has apparently receded a long way toward the head of the bay, in the middle of which a crystal peak is seen slowly drifting away with the current. In this he recognizes the huge fragment detached

from the glacier, though seldom able to detect its primitive form, the greater part, say at least six sevenths of its volume, sinking below the surface.

If Greenland, like other regions, passed through a glacial epoch, the fossil remains preserved in its sedimentary rocks show that it had also its hot and temperate periods. The old formations

FIG. 3.-MOVEMENT OF THE KANDERDLUG-SUAK GLACIER, UMANAK DISTRICT.

which have yielded Carboniferous, Triassic, and Jurassic fossils, present types of organisms comparable to those at present found in the torrid zone. The upper chalk beds, abounding in vegetable forms, analogous to those of the subtropical and temperate zones, had already been examined by Giesecke at the beginning of this century. They supplied to Nordenskjöld a very remarkable flora, especially rich in dicotyledonous plants represented by numerous. families of Cycadea, a tree-fern, and even a bread-fruit tree. At that time the mean temperature must have been as high as 68° Fahr.

The Miocene flora, whose general physiognomy corresponds to a more temperate climate, averaging about 53° or 54° Fahr., is illustrated by splendid specimens discovered chiefly in Disco Island

and the surrounding peninsulas. Quite a fossil forest is buried under the ferruginous mass of Mount Atanekerdluk, a peak which rises to a height of over' a thousand feet over against Disco, and which is now surrounded by glaciers on all sides. From these deposits Whymper, Nordenskjöld, and others have extracted one hundred and sixty-nine species of plants, of which about three fourths were shrubs and trees, some with stems as thick as a man's body. Altogether there have been discovered in the Greenland strata as many as six hundred and thirteen species of fossil plants. The most prevalent tree is a Sequoia, closely resembling the Oregon and Californian giants of the present epoch. Associated with this conifer were beeches, oaks, evergreen oaks, elms, hazel-nuts, walnuts, magnolias, and laurels; and these forest trees were festooned with the yine, ivy, and other creepers. A leaf of a Cycadea found among these fossil remains is the largest ever seen; and a true palm, the Flabellaria, has been discovered among the remains of these old arctic forests.

To develop such a flora the climate of north Greenland must at that time have been analogous to that at present enjoyed on the shores of Lake Geneva, twenty-four degrees nearer to the equator. According to the same gradation of temperature; the dry lands about the north pole itself must at the same epoch have had their forests of aspens and conifers. According to Oswald Heer, the change that has taken place in the climate since then represents a fall of 30° or 40° Fahr. for north Greenland. The interval between these two ages was marked by the Glacial period, whose traces are visible on the west coast..

Although incomparably poorer than that of Miocene times, the present flora of Greenland is sufficient to clothe extensive tracts with a mantle of mosses, grasses, and brushwood. Wherever the snows melt under the influence of the sun or of the warm east winds, herbaceous and other lowly plants spring up even on the exposed nunatakker, and to a height of five thousand feet. Owing to the uniform intensity of the solar heat, the summer flora is almost identical on the low-lying coast-lands and highest mountain-tops. True trees occur in the southern districts, where Egede was said to have measured some nearly twenty feet high. But the largest met by Rink during all his long rambles was a white birch fourteen feet high growing amid the rocks near a Norse ruin. Few trees, in fact, exceed five or six feet, while most of the shrubs become trailing plants. Such are the service and alder, which on the coast reach 65° north latitude; the juniper, which advances to 67°; and the dwarf birch, which ranges beyond 72°.

In its general features the Greenland flora, comprising about four hundred flowering plants and several hundred species of lichens, greatly resembles that of Scandinavia. Hooker and Dr.