566 Notes on Geology and Mineralogy of Afghanistan. 



wasting appearance, and are in many places fading away 

 rapidly under the influence of atmospheric agents, and some 

 indeed have been entirely swept off, leaving nothing but a 

 broad base of pebbles confusedly mingled together, and 

 affording specimens of nearly every rock to be met with in the 

 neighbouring mountains. In some parts again they appear 

 to be imperfectly consolidated or semi-indurated, exhibiting 

 indications of stratification, but usually they are composed of 

 stiff reddish clays alternating with ioose textured sand- 

 stones, the clays being often horizontally divided by their 

 layers and detached masses of foliated gypsum^ of a pure 

 and glossy transparency. 



From the situation of these crumbling hills, opposite to 

 the openings of the mountain glens, many would perhaps be, 

 led to attribute them to the agency of glaciers in former 

 years, were it not that their stratification is opposed to such a 

 doctrine, and we have moreover no data from which to infer 

 the existence of a colder climate over these tracts in former 

 ages, than now. 



My own impression is, that they belong truly to the tertiary 

 period, of which both the Bolan Pass and the Shawl district 

 possess some deposits. 



It is probable that the destruction of these hills, composed 

 as they are of friable sandstones and beds of clay, has fur- 

 nished in modern times a great portion of the soil of the 

 desert tract of Cutchi, for the materials of that arid plain 

 are arenaceous clays, containing particles of foliated gypsum. 

 The decay in these outlying hills is not however to be attri- 

 buted to any more violent agents than are now furnished by 

 the atmosphere; for their destruction is still going on gra- 

 dually and surely, and it is probable that a great portion of 

 the less indurated strata will eventually disappear. The 

 upper stratum is generally an indurated sandstone of a 

 brownish colour, while the underlying beds are of far greater 

 thickness, but are excessively yielding and friable, and not 



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