The sun, however, which had during the afternoons considerable heating power, and in one way was hindering us by making the surfaces so slushy, helped us in another way. For when I put some snow into our aluminium cooking-pot and exposed it for several hours--while we were camping--to the direct rays of the suns, I was glad to find that half the snow was thawed down, a result that, of course, saved us both paraffin and blubber. [Illustration: The Northern Party on the Plateau, New Year's Day, 1909. (_See page 211_)] On the 30th the ice ridges fronting us became higher and steeper, and strain we ever so mightily we could scarcely get the sledges to move up the steep ice slopes, and the sledges also skidded a good deal as we dragged them obliquely upwards. The glacier was now spread before us as a great billowy sea of pale green ice, with here and there high embankments of marble-like _névé_ resembling railway embankments. Unfortunately for our progress, the trend of the latter was nearly at right-angles to our course, and as we advanced the undulations became more and more pronounced, the embankments higher and steeper. These embankments were bounded by cliffs from forty to fifty feet in height, with overhanging cornices of tough snow. The cliffs faced northwards, and such serious obstacles were the deep chasms which they produced to our advance that we had often to go a long way round in order to head them off. December began with a very laborious day, and after battling on for several hours we had only advanced a little over half a mile. So we decided to camp, for Mackay and me to try to find a way for the sledge out of the maze of chasms that beset us, and for Mawson to take magnetic observations. During that afternoon we discussed our situation at some length. Most probably the Drygalski Glacier was twenty miles wide, and if we were to cross it along the course we were travelling at the rate of a mile a day it would take us twenty days to get over, even if we took no account of the unforeseen delays which our experience had already taught us were sure to occur. From what Mackay and I had seen ahead of us, our difficulties were bound, for a considerable distance, to increase rather than grow less. Under these circumstances we were reluctantly forced to the conclusion that our only hope of ultimate success lay in retreat, and so we resolved to drag the sledges back off the glacier on to the sea-ice by the way along which we had come. CHAPTER XXXVIII CREVASSES