90 GLACIOLOGY 



Royds, and was particularly noticeable in one or two of the master-cracks of Coast 



Lake. 



In crossing the glacier from north to south, opposite the lower Cathedral Rock, 

 we crossed three moraines, and could see one more lateral moraine along the south 

 side of the glacier below Descent Pass. We followed the strongest of these moraines 

 for some distance, but beyond Descent Pass it made a sharjD bend to the south, 

 and became lateral, or sub-lateral, along the upjier Cathedral Rocks, having 

 evidently been pushed out below by the ice coming down from Descent Pass. 



A few miles above the Cathedral Rocks is another series of heavy ice-falls ; 

 the ice immediately beneath them is seamed with two series of strain-cracks, those 

 in the series parallel to the length of the glacier being by far the most numerous. 

 The other series is at right angles to the first. 



A similar structure was observed between D bluff and the Solitary Rocks in 

 the northern lobe of the glacier where the ice slopes sharjDly towards its northern 

 edge. A series of parallel compound cracks cross it diagonally from the upper 

 Solitary Rock towards the lower end of the D bluff. The transverse cracks 

 forming the compound diagonal ones increase in width, as they move towards the 

 north, until many of them join up, forming long crevasses. These transverse cracks 

 vary in width from mere lines to crevasses 2 feet wide. 



The only occasion on which sounds, suggestive of appreciable movement of the 

 glacier ice, were lieard was in a camp at tlie foot of the ice-falls which force their way 

 around the southern side of the Solitary Rocks. The ice here, owing to the narrow- 

 ing of the valley, is subjected to tremendous pressure, and rather fine ice-falls are 

 developed. From the ice all round our tent sounds like pistol-shots and the popping 

 of champagne corks were heard, evidently caused by the ice relieving strain by 

 fracturing, and the strain structure mentioned as occurring below the second ice-falls 

 was also very prominent. 



EFFECTS OF THE THAW ON THE ICE OF THE FERRAR 



GLACIER 



Plate XVIII. Fig. 1 shows the effect of the thaw, about Christmas time 

 1908, near the Solitary Rocks in the Ferrar Glacier Valley. 



The effect of the thaw depends of course on the amount of direct sun's heat, 

 and largely on the state of the atmospheric currents, as well as on radiation of 

 heat from rock and rock dust. The conditions most favourable seem to be two or 

 three calm days with a full allowance of sunshine. At the end of such a period the 

 thermometer we had registered 40° F. at the end of the second day, and the glacier 

 appeared to be melting under our feet. The thaw, on the other hand, practically 

 ceases, except locally under favourable conditions, when the cold overflow breeze 

 from the plateau has been blowing for a good many hours. Its effects were so 



