MARINE EROSIOiN 207 



MARINE EROSION 



There is evidence of a considerable amount of marine erosion having taken place 

 In the Ross Sea and McMurdo Sound areas since the close of the phase of maximum 

 glaciation. At Cape Barne, for example, there is a sheer cliff about 200 feet m 

 height which has obviously been cut out by the sapping action of stormy seas in 

 summer time. During the colder periods of the year obviously iio marine erosion 

 can take place on account of the surface of the sea being crusted over with ice. 

 Flagstaff Pomt, near our winter quarters, exhibits a sheer cliff of marine erosion 

 about 80 feet in height. (Plate LIX. Fig. 3.*) The denuding force of the sea 

 also expends itself of course on piedmont ice, ice barriers, and glacier ice tongues. 

 In the case of the Nordeuskjold and Drygalski Ice Tongues the combined effect 

 of sea and wind erosion had been to round off and level off the weather side of the 

 ice tongue. The same feature was noticeable at Glacier Tongue. 



Throughout its whole length the Ross Barrier exhibited a deep wave-worn 

 groove at its base. All icebergs, excepting those quite freshly calved, showed the 

 same feature. The terraces, which were conspicuous near Cape Bird and above 

 Backdoor Bay near Cape Royds, may be due to marine erosion, or possibly may 

 mark former levels of fresh water lakes at the margin of the great lobe of the Ice 

 Barrier when it completely filled McMurdo Sound. In this case these terraces are 

 comparable with the parallel roads of Glen Roy or the seter of Scandinavia and 

 Greenland. Even when high waves are raised in the open sea by the action of 

 blizzards, like the great blizzard of February 16, 17, and 18 in 1908, their effect on 

 the coast is not enthely destructive, but in the long run is protective, for towards 

 the end of that blizzard we observed that the coast-line for some distance inland was 

 coated with a thick crust of ice formed from the freezmg of the spindrift and spray. 

 This effectually protected the rocks frmging the coast from further marine erosion. 

 The protective character of sea spray in strengthening and consolidating the snow- 

 drifts of the ice-foot has already been explained in Chapter VIII. At the same 

 time, it is obvious that the wetting of extensive cliff faces with sea spray by the 

 blizzard winds, followed by a quick freezmg of the films of sea water, which have 

 penetrated the joints and cleavage planes of the rocks, must have a very strong 

 destructive influence, owing to each film of ice thus formed wedgmg off flakes of 

 rock. In this way marme erosion considerably aids normal frost weathering in the 

 work of rock destruction. 



* See also Plate II. Fig. 2 illustrating the great wave-worn cliflF at Cape Washington. 



