Our retreat began early on the morning of December 2, and after a week's struggle on the glacier Mackay, just before camping-time on the 9th, sighted open water on the northern edge of the Drygalski Ice Barrier, from three to four miles away. This convinced us that we could not hope for sea-ice over which to sledge westwards to that part of the shore where we proposed to make our final depot, before attempting the ascent of the great inland plateau in order to reach the Magnetic Pole. On the 10th, however, at the end of the day's sledging we rejoiced to find ourselves off the true glacier type of surface, and on to one of the undulating barrier type. This improvement enabled us to steer westwards, and on the following day we had a fine view of "Terra Nova" Bay, and as far as could be judged the edge of the Drygalski Ice Barrier on the north was scarcely a mile distant. So surprised were we at the general appearance of the outline of the ice, which did not seem to agree with the shape of this region as shown on the Admiralty chart, that we halted a little earlier than usual to reconnoitre. Mackay started off with the field-glasses to a conspicuous ice-mound about half a mile to the north-west, Mawson began to change his plates, while I went out with my sketch-book to get an outline panoramic view of the grand coast ranges in sight. So few had been the crevasses of late that I failed to take my ice-axe with me and I had scarcely gone half a dozen yards from the tent when the lid of a crevasse collapsed under me, and let me down nearly up to my shoulders. I only saved myself from going right down by throwing out my arms and staying myself on the snow-lid on either side. The lid was so rotten that I did not dare to move for fear that I might be thrown into the abyss, but fortunately Maws on was near, and on my calling to him he brought an ice-axe and chipped a hole in the firm ice on the edge of the crevasse nearest to me. Then he inserted the chisel edge of the ice-axe in the hole and, holding on to the pick-point, swung the handle towards me. Grasping this, I was able to climb out on to the solid ice. On the following day we sledged on until we were close to the ice-mound already mentioned, and decided that as this mound commanded such a general view of the surrounding country, it must also be a conspicuous object to any one approaching the Drygalski Glacier by sea from the north. And so we decided that as we could find no trace of the "low, sloping shore"--as it was called on the Admiralty chart--we would make our depot at this spot. We estimated that we still had 220 miles to travel from this depot on the Drygalski Glacier to the Magnetic Pole, and therefore it was necessary to make preparations for a journey there and back of at least 440 miles. We considered that with _détours_ the journey might possibly amount to 500 miles.