Polar Exploration. William Speirs Bruce

of gently undulating or more or less flat land, and even what would be shallow sea were the ice not there, are fed not only by the intermittent falls of snow year after year and by the drift brought from the mountains and inland ice, but also by glaciers which act as feeders to these low-lying ice-fields, and which keep on pushing the whole mass seaward until great flat-topped pieces, exactly similar in shape to the flat-topped snow islands from the roof, float out to sea.

      One of these great ice-fields lies to the south of New Zealand, terminating in an ice cliff in the Ross Sea, which is usually known as the Ross Barrier. This great barrier was discovered by Ross in 1840, and was visited ​by him during two successive seasons. It has been now visited by several expeditions during recent years, especially by those under the leadership of Scott and Shackleton. This ice cliff, varying in height from almost sea-level to about 100 feet above the sea, stretches in an east and west direction between Mounts Erebus and Terror and Edward Land for a distance of nearly 300 miles. It is quite easy to imagine that pieces many miles in length and breadth might break off and float out to sea, as well as almost innumerable smaller pieces from a mile or two in length and breadth to only a few feet. This is exactly what does happen, and it certainly must occur in other parts of the Antarctic Regions besides the Ross Sea. Those countless bergs seen by us on board the Balæna in 1892–93, and again those seen by all on board the Scotia during her two cruises in the Weddell Sea, as well as those that drifted past the South Orkneys for eight months during the winter of 1903, and those seen by Charcot between 70° W. and 124° W., certainly did not come from the Ross Barrier, but from similar barriers, perhaps even more extensive than the Ross Barrier. Other barriers must occur elsewhere in the Antarctic Regions to account for the host of table-topped bergs that are scattered all over the Great Southern Ocean, and indeed ​Nordenskjold has described one on the east coast of Graham Land. The greater size of the bergs on the Atlantic Ocean than on the Pacific side of Antarctica indicates the greater scale of the ice-sheet towards the Weddell Sea than towards the Ross Sea. Moreover, after the reports of the latest expeditions, it appears probable that the larger and more numerous bergs that occur to the south of the Atlantic and Indian Oceans are not wholly comparable in their formation and structure to those found in the Ross Sea, in the neighbourhood of the Ross Barrier.

      The whole question of the Ross Barrier and a barrier described by Nordenskjold on the east coast of Graham Land, which he calls an "ice-terrace," is most interesting. Buchanan and Nordenskjold have pointed out that these barriers, or ice-terraces, are composed of névé, not glacier ice, and with the Graham Land Barrier this especially appears to be the case. Névé, however, precludes the idea of flow, and we have the definite record of Scott that Barne, on visiting a dépôt Scott had laid down, found that it had "moved on." "Thirteen and a half months," says Scott, "after the establishment of the dépôt, he measured its displacement, and found it to be 606 yards. And thus almost accidentally we obtained a very good indication of the movement of the ​Great Barrier ice-sheet." (The Voyage of the Discovery, Captain R. F. Scott, vol. ii, p. 300: London, 1905.)

      Doubtless, the Ross Barrier is fed considerably from the southern glaciers that run into it. Speaking of the discharges of the glaciers from the névé of the inland ice plateau, Scott says, "From observations which I have mentioned one must gather that the movement of this most northerly of these discharges is very slow, but judging by the movement of the Barrier, the southern ones are more active."

      Now the only good channels by which glaciers run into this Barrier, and that are of importance and that come down from the Inland Ice-sheet or Inland névé over which Scott, Shackleton, Armitage, and David have led expeditions, probably come into it at half-a-dozen so-called inlets, such as Skelton, Mulock, Barne, and Shackleton Inlets, and the largest and most definite feeder known is the great glacier that Shackleton discovered and travelled up from the Barrier to the Inland Ice, namely, the Beardmore Glacier.

      But the ice that pours out of this evidently rapid-flowing and huge glacier is about 360 nautical miles from the face of the cliff of the Ross Barrier. Now, according to Scott's estimated rate of flow of the Barrier at 606 feet in thirteen and a half months, it would ​take nearly 1,200 years for that ice to reach the Barrier face. Meantime the whole glacier—or should it be called ice-field?—is accumulating ice by snowfall and by drift from the surrounding mountains and plateaux, and must therefore be chiefly and, indeed possibly, wholly composed of this in the form of névé, but with this marked character, that it is a moving, and not a stationary, névé. At some future time, with more space at my disposal, I propose to further discuss this point, because a general definition of a névé is ice that collects in a lofty plain, from which glaciers flow out but which does not actually flow itself. The structure of névé ice is also distinct from that of glacier ice, the grain of which, in each case, is the leading feature. The flow of the Ross Barrier is, I believe, different from that of an ordinary glacier which comes running and tumbling down a gully or a glen, like water in a river down a river course, for in this case it comes over a low stretch of flat or gently shelving land or shallow sea and is ultimately afloat. It is rather pushed from behind than moving forward by its own gravitation. The flow is probably different also in this respect, that, like a rapid river, there is a sort of rotatory movement of the ice of a glacier which is plastic by virtue of its disintegrated grains, each surrounded with a film ​of saline water, whereas very little of such movement would occur in the case of the barrier ice, and consequently the marks of stratification remain visible in the bergs which are calved from it. Except for a certain amount of glacier ice, which comes in from the feeders mentioned, the Ross Barrier is made up almost entirely of successive years' additions of snow and drift that fall upon it and accumulate in definite layers. The simile, therefore, that I have already given of the snow layer on a roof is all the more striking, only it is not the accumulation of snow of a single fall, not even of snow of a single year, but probably of snow that has fallen, say, during a thousand years.

      It would not do to pass by Nordenskjold's important observations with regard to his "ice terrace" at Graham Land, and it is best to quote his own words (Antarctica, Dr. Otto Nordenskjold: London, 1905) as follows: "At our noonday rest I was nearly falling into a broad crevasse, but said nothing of the matter, in order not to make the others anxious. But all of a sudden the ice became more uneven, and at 5 p.m. our march came to a sudden and unexpected end in front of a canal-like crevasse, some 20 metres (65 feet) broad and almost as deep, which seemed to run in towards the land as far as the eye could reach. This ​crevasse was of great interest, as it gave us a very clear idea of the inner structure of the ice. The same splendid stratification could be seen here as that which often occurs in the large icebergs, thus proving that the ice had been formed of layers of snow deposited, during long periods, the one upon the other, and being, too, a new proof of the transition, found in these regions, from glacier to sea ice. I think, too, that the Antarctic icebergs need not necessarily have their origin on land, but that they can also be built up on a base of sea ice in shallow water near the land."

      Nordenskjold's idea that Antarctic icebergs may be built up on a base of sea ice is not altogether new, for Captain Cook previously made that suggestion, though without the great scientific qualifications that Nordenskjold has for expressing such an opinion, and also without the knowledge of the existence of these barriers or ice-terraces that have been discovered in the Antarctic Regions by Ross and Nordenskjold since Cook's voyage. But from my experience in the Polar Regions during twenty years I cannot conceive of these Antarctic bergs being built up from a base of sea ice.

      There appears to be little doubt, however, that the Ross Barrier is to a great extent afloat. But Sir George Darwin's "guess" ​"that the bay behind the barrier stretches past the South Pole and to the east of it as far as latitude 80°" is dangerous. All the evidence at our disposal from observations taken in the region of the Weddell Sea condemns the idea that there is "an arm of the sea through to Weddell's Sea." (Tidal Observations of the British Antarctic Expedition, 1907. Sir G. Darwin.)

      The question is a most intricate and difficult one, and cannot be properly solved until one or more expeditions set themselves to work in definitely making examinations of the ice of the different layers of the barriers, of the different layers of the bergs that have been shed from them, and various detailed measurements, and, what is perhaps as important as anything, the demarcation of the exact extent of these barriers, and