I.] GEOLOGICAL OBSERVATIONS 343 



March 1, 1903. — A water-hole, or an area uncovered by floe- 

 ice. 



April 24, 1903. — Sun below the horizon ; thickness 3 feet. 



August 23, 1903. — Re-appearance of the sun ; thickness 3 feet 

 6 inches. 



December 5, 1903. — Nearly midsummer; maximum thickness 

 8 feet 5£ inches. 



January 5, 1904. — Summer month ; thickness 5 feet 10 inches, 



January 28, 1904. — Air becoming colder ; a water-hole. 



The ice is therefore dissolved from below, and the water-hole 

 observed three years in succession off Cape Armitage is further 

 proof of this action of the sea-water. 



The sea-ice in McMurdo Sound gradually creeps north during 

 the winter, but the ice-foot protecting the land prevents the sea-ice 

 acting as an abrading or transporting agent to any great extent. 



The Shore-ice may be taken to include all ice that fringes the 

 shores of South Victoria Land and remains firmly frozen to them. 

 Three types may be distinguished : 



(a) The fringe due solely to the spray from the sea which 

 freezes on the land. This is the 'typical ice-foot,' and owing to the 

 small rise and fall of the tide its height never exceeds three feet. 

 The chief function of this fringe is conservative, for it protects the 

 beach from the action of floating ice and eroding breakers. 



(b) There is a border of glacier-ice around the land of Winter 

 Quarters. This ice has no apparent source. It slopes gently sea- 

 wards, and ends as a cliff which varies in height from six feet to 

 300 feet, and the distance between the cliff and the bare land 

 varies from ten yards to a mile. This fringe is even more effective 

 than the ice-foot as a conservative agent, for its surface is inclined 

 at an angle of less than 20°, and seldom allows stones to roll over 

 it on to the sea-ice. 



(c) The third type of shore-ice is more in the nature of a 

 'piedmont.' The great snow-fan between the hills and the 

 stranded moraines on the west side of McMurdo Sound maybe taken 

 as an example. This mass of snow is about ten miles long and 

 five broad, and the whole of it is aground. It has no obvious 

 source, and the surface rises from a few feet at the seaward edge 

 to about 1,000 feet on the sides of the foothills. As it is 

 practically motionless, it must afford a very material protection to 

 the land. 



