90 



REPORT ON ANTARCTIC SOILS 



GENERAL NATURE OF THE SAMPLES 



Number 1. Black soil ; mechanically a light loam. Largely derived from kenyte 

 lava, the prevailing rock of the neighbourhood. From a position six inches below the 

 surface at Cape Eoyds, Ross Island, Antarctica. 



Number 2. Dark soil ; mechanically a very sandy loam. Largely derived from 

 kenyte lava, the prevailing rock of the neighbourhood, but with some admixture of 

 ice-carried morainic mud. Taken between the surface and a depth of three inches, but 

 not including the half-inch of surface gravel ; Cape Royds. 



The water-soluble constituents form little acicular crystals in the soil, and are probably 

 combined in the form of chlorides of sodium, potassium, and magnesium ; sulphates 

 of magnesium, calcium, and potash ; and carbonate of soda. 



Number 3. Black soil ; mechanically a very sandy, gravelly loam. Partly derived 

 from kenyte lava and partly from morainic matter. From between one and four inches 

 below the surface, on the top of a moraine mound, Cape Royds. 



Number 4. Light-coloured irregular and indefinite soil. Moraine silt derived largely 

 from Gneisses and Schists. From Dry Valley, South Victoria Land. 



TABLE A. MECHANICAL ANALYSES OF ANTARCTIC SOILS 



COMMENTS 



In the table on p. 92 I have compared the above with 



(a) a soil derived from alkaline lavas at Mittagong, N.S.W. ; 



(b) a soil derived from basalt, Tweed Heads, Queensland ; and 



(c) a granite soil from the south coast (Moruya, N.S.W. ). 



From this table (p. 92) it appears that in spite of the abundant moisture from 

 melting snows the leaching out of mineral plant food does not take place with 

 anything like the rapidity of this process in moist soils of less frigid climate. 



Rock weathering in Antarctica is much more a process of mechanical disintegration 

 than of chemical change into a normal soil. Zeolitic minerals form by slow hydration ; 

 carbonates also form very slowly, but the solution and removal of these acid soluble 

 minerals are much slower processes than their formation. So these minerals 

 accumulate in the sand grains without being leached away and thus breaking up the 

 grains into finer particles. 



* Impalpable matter, chiefly clay. 



