418 J. T. Jutson 



Effects of the Sand on the Topography. 



' The effect of the spread of the sands has been to divert some of 

 the present small stream courses at Comet Vale and to blot out the 

 drainage to the west of the same place, as there is evidence of a 

 wide north-south valley there, which must have been a drainage 

 line before the sands spread across and choked it. Tlie water courses 

 which originally ran westward to this old valley from the laterite 

 ridge have also been smothered. The general result is the substitu- 

 tion of the sand ridges and sand plains for the old fluvatile 

 topography. 



Significance of the Sand Distribution as to the Work of 

 the Wind in this and other Areas 



The numerous sand ridges of the district show that the wind has 

 removed a very large quantity of sand, and hence its influence on 

 the general erosion of this portion of the country must be con- 

 siderable. 



The most important sand distribution of the district, however, is 

 the belt of sand on which the township of Comet Vale stands. This 

 has already been described as a gently-sloping sand plain on the 

 western flanks of the laterite ridge, and falling westwards. Ihis 

 fiand belt, as also shown above, passes over the saddles of the ridge 

 and then into the '' sand glaciers." The sand on the western flanks 

 of the ridge is wind-blown beyond question. There are no rocks at 

 the ridge or thereabouts that could have provided the material; 

 the sands, as seen in artificial sections, are remarkably homo- 

 geneous in texture and materials; the waste from the laterite ridge 

 lies buried beneath the sands; and the sands are continuous with 

 the wide sand area to the west. Ihese facts, together with the 

 •distribution of the sand up the flanks of the hills, through the 

 passes and thence on the opposite side of the ridge as '' sand 

 :glaciers," leave no doubt as to the wind origin of the sand. 



That being so, there exists a sand slope, smooth and unbroken 

 by sand ridges, and to all intents a sand plain; and this sand 

 plain has been formed by the wind. Sand plains are of wide 

 ■occurrence in inland Western Australia, and althougli the wind 

 was thought to be an important agent in their formation, direct 

 evidence as to its action is not always obtainable. Ihe Comet Vale 

 evidence may help to determine the matter, although of course each 

 area must be independently investigated. It, however, suggest^ 



