Geology 



There could be little doubt that the glaze on the 

 pebbles from the red beds had been produced by the 

 action of wind-blown sand, and as they occurred not 

 only upon the surface of the ground, but also deep 

 within the rock, the polishing could not have been 

 effected in recent times. We concluded, therefore, that 

 the materials of the rock itself must have been accumu- 

 lated by the action of wind in some ancient desert. The 

 curious three-keeled stones we recognized as similar to 

 the "dreikante" figured in our text-books as occurring 

 in deserts and produced from ordinary pebbles by the 

 sand blast. 



The red sand grains suggested rounded particles of 

 oxide of iron, and in order to determine if this were their 

 nature we boiled some of them in acid and applied the 

 usual tests. 



On boiling the red grains with dilute hydrochloric 

 acid the liquid rapidly became of a deep orange colour, 

 but it was found that the greater proportion of the sand 

 was left as an insoluble residue. On washing and ex- 

 amining the residue it was found to consist of remark- 

 ably well-rounded grains of quartz, all having, in a 

 marked degree, the glaze so characteristic of the 

 dreikante and other pebbles. The solution was found 

 to contain ferric chloride, and from this it was concluded 

 that the red coating or pelicle of the sand grains con- 

 sisted of ferric oxide. 



The roundness and desert glaze of the sand grains 

 proved that they had been accumulated in an arid 

 region by the action of the wind, the further fact that 

 they were graded in layers of different sizes supporting 

 this view. 



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