348 THE VOYAGE OF THE 'DISCOVERY' [Appx. 



proceeds at a greater rate where ice and gravel occur together. 

 In the channel at the foot of Knob Head, and also in the Dry 

 Valleys near Finger Mountain, englacial matter may be seen 

 below a layer of ice at least fifty feet thick. At the former locality 

 two streams of ice flowing in opposite directions meet, glacial up- 

 thrust takes place, and the boulders which are raised to the 

 surface form an ordinary medial moraine. 



Supra-glacial material is very scarce if we take the Tasman 

 Glacier of NeAv Zealand, or the Zmutt Glacier of the Alps, to be 

 normal. The lateral and medial moraines of the Ferrar Glacier 

 consist of long lines of stones which are sometimes three feet in 

 diameter, and are seldom accompanied by finer material. These 

 lines are usually about thirty yards in width, and the larger boulders 

 are generally five or six feet apart. 



The stranded moraines both on Cape Royds and on the main- 

 land often have a core of ice, and it is often difficult to make sure 

 what proportion of a given moraine is formed of rock matter. 

 During the summer this ice melts, and the finer material is separated 

 from the boulders and gravel by water action, so that stratified and 

 false-bedded sands and gravels are now being produced in an area 

 which is virtually the centre of a continental ice-sheet. 



Among the moraines on the west side of McMurdo Sound, as 

 well as on one of the Dellbridge Islands, and among the moraines 

 on the west side of Discovery Gulf, great deposits of sodium 

 sulphate in well-formed crystals have been found. Among the 

 isolated moraines in the bay between Black and White Islands, 

 large bosses or mounds of the same white salt have been seen ; 

 and at one spot near White Island a mass of perfect crystals was 

 found on the surface of pure ice. In the White-Black Island Bay 

 balanus shells and sponge spicules occurred upon the ice in 

 association with this salt. The occurrence of this salt, mingled 

 with shells and ice-scratched stones, is a freak of Nature which is 

 difficult to explain. 



Temperatures -A^. fixed depths in the ice fringing the land around 

 Winter Harbour were determined during the year 1903. It will 

 suffice here to note that the highest temperature recorded at a 

 depth of six feet was -9° C, and the lowest - 24-4° C. The change 

 throughout the year was very gradual : the minimum reading 

 was made some time after midwinter, and the maximum in 

 Januar}'. 



Observations of temperature in crevasses at greater depths 



