v. — GE OL G Y 



Art. LXVII. — On Wind-formed Lakes. By J. C. Crawford, F.G.S. 

 [Read before the Wellington Philosopliical Society, 13th September, 1879.] 



The scientific world has had its say upon rock-basins and the action of 

 glaciers in scooping out beds of lakes ; and sorae, indeed, venture to work 

 out the solid materials in that manner in such lake-basins as that of 

 Wakatipu, with its sm-face 1000 feet above the sea, and its bottom 300 feet 

 below the sea-level. I have, however, nowhere read of wind-formed lake- 

 basins ; and I, therefore, propose to describe shortly how they may be and 

 are formed. 



If we suppose a flat, composed of sandy soil say, more or less covered 

 with vegetation, and on it a slight depression, which may be caused by the 

 action of the wind blowing the loose soil away — in this depression storm- 

 water will lodge. This lodgment destroys the grass and other land- 

 plants which may have been growing on the surface ; and when the pool 

 has dried by evaporation, the surface of the depression is in a fit state to 

 be again acted upon by the wind, any aquatic plants which may have 

 sprung up being destroyed by the drying-up of the water. A further 

 deepening and possible enlargement of the pool takes place, and this 

 process goes on until rain again falls and forms a temporary lake. At 

 length the lake may attain sufficient depth to retain its water throughout 

 the year, and then vegetation may spring up round its borders, and a 

 stability of years or of centuries may be attained. 



There have been, I think, a considerable number of wind-formed lakes 

 in New Zealand, many of which have been destroyed by the effects of 

 colonization and the introduction of stock. The fires of the settlers, and 

 the grazing and tread of cattle, destroy the vegetation on the shores of the 

 lake, the sand is set blowing, and the lake is either destroyed or altered 

 in position. 



I am inclined to think that part of the Wairarapa Lake has been formed 

 by the wind. There is a line of sand-hills on the eastern shore which there 

 is little doubt is composed of sand blo^yn from the lake-bottom when that 

 had di-ied up. I by no means suppose the whole lake to be wind-formed, 

 because, as a rule, I do not suppose it to have, or have had, a sandy bottom ; 



