physical geography than had ever been afforded to previous explorers, and their observations on this point form not the least valuable part of the results of the expedition. The ice was from eighty to one hundred and fifty feet in thickness, judging from the height of the portion above water; and the surface was rugged in the extreme. Apart from the masses of hummocks thrown up during disruptions, the surfaces of some of these ancient floes were broken into hills and dales, the hills varying from ten to fifty feet in height. This, of course, must be the result of ages of drift, and of alternate frost and thaw. The floes far out to sea were infinitely heavier than those nearer the coast. The formation of this palaeocrystic sea is analogous to the well-known course of formation of glaciers. Year by year layer after layer is added to the upper surface, the lower layers becoming harder, owing to the superincumbent weight, until they are converted into snow-ice. The method of this formation was studied by means of the huge masses, well-termed floe-bergs, which were cast upon the beach. Some of these were split by the frost, offering complete sections, which were carefully drawn. In some instances they showed lines of darker color, at distances of many feet from the existing surface, indicating sections of the pools of water and intermediate rises which, during some far-distant summer, had been on the surface.
Such a sea as this is never navigable, but there was the clearest evidence of frequent, if not annual, disruptions. The vast masses of hummocks, thirty to fifty feet high, and sometimes a quarter of a mile wide, which occur at frequent intervals and divide the ancient floes, are evidence of very violent encounters between the floes; and mud found on the ice some miles from the shore is also a proof of movement. The ice traversed by Captain Markham consisted of ancient floes of small extent and very uneven surface, separated by lofty ranges of rugged hummocks, and there were occasionally narrow streams of this year's ice, that is about five feet four inches thick, connecting the floes. The drift-wood which was found on Prince Patrick and Banks Island, and also on the scene of Captain Nares's discoveries, is likewise a proof that the palaeocrystic sea is subjected to movements the exact nature of which is uncertain; for this drift-wood must have come from the banks of Siberian, rivers.
At the same time the periodical disruption is clearly only partial; and the movement of a particular floe is but slight during one season. For there is no sufficient outlet, apparently, for the ice of this sea. The age of the ice is a sufficient proof of this. Sherard Osborn describes the sea of ancient ice as "a vast floating glacierlike mass, surging to and fro in an enclosed area of the Arctic region." It is bounded on the south by the shores of North America; on the east by Banks and Prince Patrick Islands, Grant Land, and the north coast of Greenland; and on the west by Kellett Land and other unknown obstacles north of the Siberian coast; so that it has an area of about one thousand two hundred miles both from south to north, and from east to west Its movement is slight, and the "Enterprise" and "Investigator" observed that it never moved off from the shore more than a mile or two, and then surged back again. The known outlets to the sea of ancient ice are very narrow. Fragments, forming great ice-streams, pour through Banks Strait into Melville Sound, but they never get west of Griffith Island, and are never seen in Barrow Strait. They appear to fill up McClintock Channel, which can never be navigable. Here Osborn saw them in May, 1851, and he describes the floe as of great antiquity, and as like a heavy cross sea suddenly frozen solid, the height of the solid waves being twenty-five feet. Allen Young reached Osborn's point of observation, and formed the same conclusion. He actually attempted, like Collinson, to travel across this palaeocrystic floe, but found it quite impracticable owing to the rugged nature of the ice.
Thus two explorers had attempted to tackle the ancient ice before the memorable journey of Captain Markham — namely, Sir Richard Collinson and Captain Allen Young, and they can well appreciate Captain Markham's difficulties, and the severity of the struggle he entered upon. There is another outlet for the sea of ancient ice by Robeson Channel, but it is very narrow, and the ancient and heavy floes do not get much further south than Lincoln's Bay in 82° N. Lat, or thereabouts, according to the season. The "Polaris" did not encounter them; but the "Alert" was at one time actually beset in ancient floes off Cape Lincoln, before rounding Cape Union, and was in great danger. Their size and position in the strait would vary according to the season. Fragments of the ancient ice, no doubt, stream down the south coast of Greenland and round Cape Farewell; and it would be a matter of great interest to explore the
