416 J' ^'- Jutsov : 



end breaks into three branches which are separated by troughs a 

 comparatively few feet deep. The bottoms of these troughs are 

 well above the surrounding sand plains, so that they are part of 

 the ridge. Between two of these branches there is a distinct 

 roughly circular basin in the sand having a diameter of about 30 

 or 40 yards and a depth below the rim of perhaps 25 feet. This- 

 is the type described by Cornish^ as a fulj. 



(c) Ihe typical forms of sand accumulation known as " sa7i(r 

 glaciers,'' which have been described in various parts of the world 

 are due to sand being blown up the sides of hills or mountains, 

 thence finding a passage through any passes or saddles, and 

 spreading out on the opposite sides to form wide fan-shaped 

 plains. This is Free's definition. 2 Cornish^ restricts the term to- 

 a horizontal plateau of sand terminated by a talus, as steep as the 

 sand can rest. The forms at Comet Vale are, on a small scale, 

 closely related to those referred to by Free; hence the present writer 

 retains the term as a convenient one. 



Immediately to the east of the town is a north-north-west trending^ 

 ridge of laterite forming part of the laterite high lands previously 

 referred to. This ridge is cut into by amphitheatres, which form' 

 the heads of the small watercourses which formerly extended Avest- 

 ward ; and it also has several comparatively low passes or saddles. 

 The lower western flanks of the ridge have a smooth unbroken- 

 sloping sand plain with a gentle but still a definite fall to the west. 

 Artificial openings, such as mining shafts and costeans, show that 

 the sand of this plain is here from a few inches to about ten feet 

 in depth, and that it is fine-grained, well-rounded and homo- 

 geneous. It shows, however, no planes of stratification, but would 

 probably do so if it became consolidated and subsequently weathered 

 out. Below the sand there is a deposit from one to six feet thick, 

 made up largely of angular fragments, up to three or four inches 

 in size, of laterite, similar to that of the laterite ridge referred to 

 above. Ihis material is evidently derived from such ridge and 

 represents the debris spread over the surface before the sand 

 drifted upj the slope, tlie cai-rying of such rock waste no doubt 

 being due to the occasional tiny streams which ran from the 

 amphitheatres above described, and to the fact that such waste 

 always tends to drift by gravitation from higher to lower slopes.. 



1 Cornish, V.— " On the Formation of Sand Dunes." Geogr. .Toiini., 1897, pp. 2».^■29«. 



2 Free, E. K.— "Tiie Movement of Soil Material by the Wind." U.S. Dept. of Ajfric, Bureau 

 Of Soils, Bull. No. 68, Washinjrton, 1911, p. 57. (Footnote a). 



3 Op, cit., p. 286. 



