NOTE OX THE THABA BOSIGO SAND-DUNES. 



By Prof. George Hardy Stanley, A.R.S.M., M.I.M.E., 

 M.I.M.M., F.I.C. 



( Plate 2.) 



During the visit of the Association to Thaba Bosigo. Basuto- 

 land, in [909, the sand-dunes were not the least interesting of 

 the natural features inspected, and considerable speculation was 

 indulged in regarding their origin. 



The writer brought hack a sample for microscopic examina- 

 tion, and found that it exhibited the usual characteristics of 

 wind-blown sand, as will he evident from an inspection of 

 Fig. 1. the particles being of approximately uniform size, and 

 well polished and rounded. 



Fig. 1. 



The origin of the sand, however, is not at first apparent. 

 but from a consideration of the local features it would appear 

 to be a result of wind action, more or less as detailed in the 

 following statement. 



The mountain itself is of the flat-topped type so common 

 in the country, the top consisting of a stratum of sandstone 

 which forms an undulating plateau covered to a large extent 

 with grass. 



At the sides this top stratum forms nearly vertical cliffs 

 as shown in the upper photograph, Plate 2, the slope commencing 

 and running down from the bottom of this, and being strewi 

 with loose blocks of sandstone. 



The- sandstone consists of layers of variable thickness 

 which have weathered to different figures, as seen clearly in tb 

 middle photograph, Plate 2, the removal of the softer hands 

 leaving overhanging shelves of harder rock, and in some case< 

 forming caves. 



