Sand Ridges in Western Australia. 415 



The vegetation 9^8 a whole is stunted and xerophytic, and there 

 ds much bare ground between the plants. 



Nature and Distribution of the Blown Sands. 



The blown sands of the district may be divided into (a) sand 

 plains, (b) sand ridges or dunes, and (c) ** sand glaciers." 



(a) The sand plains cover large areas to the west and to the 

 south of Comet Vale. They may be almost level or undulating. 

 Ihe township of Comet Vale is largely built upon a sand plain 

 which slopes gently downward with a smooth and unbroken surface 

 to the west from the western flanks of the north-north-west trending 

 laterite ridge immediately to the east of the township. The sands 

 ■of the sand plains are generally fine-grained and consist mostly of 

 •quartz. They contain a certain amount of fine material which 

 tends to make the surface somewhat firm. The surface is thus 

 composed in, places of what might be termed a loamy sand. 



(b) The sand ridges or dunes are numerous, and occupy con- 

 siderable space to the west and to the north of Comet Vale. A 

 prominent ridge, which the Avriter has named the Rifle Range 

 Ridge, lies to the south-west of the town ; and on both the northern 

 .and southern sides of the Quarry Arm of Lake Goongarrie, steep 

 ridges rise from the edge of the lake. For about four miles north- 

 ^vards from the township the railway cuts through many. 



The ridges have sides) varying in slope from steep to gentle, and 

 rise from the sand plain to a maximum height of about 50 or 60 

 feet.i They are roughly parallel to one another and have a general 

 •east and west trend, with variations towards west-north-west and 

 towards east-north-east. If the westerly winds be the dominant 

 •one.s, as they appear to be, the ridges are longitudinal. 



Tlie ridges vary in their distances apart, some being practically 

 isolated, and others within a quarter of a mile of one another. 

 Some reach a length of over lialf a mile. Fine well-rounded grains 

 of quartz and ironstone, the (piartz predominating, foi'ni tlie sands 

 t3f the ridges, and the surface layers at least seem to be free from 

 the finer material, which no doubt has been blown or washed out 

 from the sand. Between tlie ridges the sand is mixed with finer 

 material, as already mentioned when describing the sand plains. 



Some of the ridges are compound ones, being forked, with two 

 or more branches. The Rifle Range Sand Ridge towards its western 



1 Some elevated irrejfularly shaped areas of Itlown sand have lonjf peiitle slopt-s and, in some 

 cases, flat tops. They are apparently due to some local phase of wind action, but they arc not 

 further discussed in this paper. 



