THE HEAUT OF THE ANTARCTIC 



changes might occur without being due to geological 

 faulting. 



The sectional drawing shows the state of Ross Sea, and 

 of McMurdo Sound during the maximum recent glacia- 

 tion. It indicates that the ice attained a maximum thick- 

 ness formerly of nearly 4000 ft. in parts of McMurdo 

 Sound from which it has now^ entirely retreated. Since 

 the voyage of Ross, in 1841, the front of the Great Ice 

 Barrier has retreated southwards in McMurdo Sound to 

 the extent of about thirty-five miles, as determined by 

 Captain Scott. Signs of waning glaciation are conspicu- 

 ous all the way from Mount Nansen to the furthest south 

 mountains examined by the Southern Party of this ex- 

 pedition in latitude 85° 15' South. For example, the 

 summit of Mount Hope, discovered by the Southern 

 Party in latitude 83° 33' South, was strewn with erratics, 

 at an altitude of fully 2000 ft. above the general level of 

 the adjacent surface of the glacier ice. 



GLACIOLOGY 



The glacial phenomena of the region examined by 

 us are due to the action either (a) of Water substance 

 in the form of (1) sea ice, and ice-foot or shore ice; 

 (2) glacier ice; (3) barrier snow and ice-fields ; (4) inland 

 ice and neve fields; (5) icebergs; (6) pack-ice; (7) thaw 

 water forming surface lakes, and surface, englacial or 

 subglacial streams; or (b) to the action of wind; or (c) 

 to that of seasonal or diurnal changes of temperature. 



(a) Action of Water Substance 



(1) Sea Ice. — We made a series of observations, by 

 cutting holes from time to time through the sea ice, to 

 ascertain its maximum thickness throughout the area, and 



288 



