180 GLACIOLOGY 



thick masses of old consolidated drift, partly cemented by frozen sea spray, are 

 broken out at least as far inshore as the tide crack. These large dislodged blocks, 

 containing much finely-divided rock debris, together with coarser lumps of rocks, 

 are floated northwards into Ross Sea, and driven by the south-easterly blizzards 

 towards Cape Adare, or even farther northwards. Sooner or later they part as 

 they thaw with their burden of rock debris, which, as already stated, is largely 

 formed of angular fragments of fresh felspars. Thus such fragments are evidently 

 being scattered far and wide over Ross Sea, where they must become intermixed in 

 the bottom deposits of that sea with diatomaceous and sponge spicule ooze. 



In regard to the accumulation of drift snow on the ice-foot at Cape Royds, we 

 observed that a few drifts began to form over the sea ice after its freezing during 

 April, but it was not until the wind and snowfall on June 25, 26, 27, and 28 that 

 these snow-drifts reached any great thickness. By the latter of these dates the 

 drifts had become several feet in depth, and by July 10 were on a level with the top 

 of the ice-foot of the preceding season, and where this ice-foot was lower had even 

 begun to overflow it. Two or three days later the tide cracks had burst right 

 through these drifts. 



SEA ICE 



If again the chronological order of our experiences be followed, we may pass to 

 the description of Plate XL VII. Fig. 3. 



This represents dense screwed pack ice with a large berg frozen into it. We 

 sighted this during our second attempt to reach King Edward VII. Land in January 

 1908. This pack appeared to be certainly of more than one season's growth, and the 

 interspaces between the crushed masses of ice are filled in with old snow. The pack 

 proved to be far too heavy to admit of its being penetrated by the Nimrod. The 

 berg shown has probably broken ofi" from the Great Ice Barrier. 



Plate XL VII. Fig. 2 shows the fast ice, against which the Nimrod can be seen 

 pressing in the middle distance : to her right are fragments of the drift pack. This 

 photograph was taken in December 1908. The foreground is a hill of kenyte lava, 

 in the neighbourhood of Cape Royds. 



Plate XLVIII. Fig. 2 shows the Nimrod forcing her way about the same time of 

 the year along the narrow lane in the fast ice. A pressure ridge of sea ice can be 

 seen just in advance of her bows. 



Plate LII. Fig. 3 shows the appearance of large masses of floe ice in the neigh- 

 bourhood of Granite Harbour as seen in December 1908. These floes are covered 

 to a depth of several inches with soft snow. About this time of the year the sea 

 ice was becoming much honeycombed, and the thickness varied from a few feet up 

 to about 5 feet. 



Plate LII. Fig. 2 shows brash ice formed from the complete shattering of floe 

 ice after a blizzard in McMurdo Sound. As the summer blizzards often brought 



