JU11A. QUARTZ ROCK. 217 



these rocks, it occasionally lies in immediate contact with 

 granite. 



The external character which quartz rock gives to a 

 country, and particularly to the high mountains that are 

 composed of it, is remarkable, and leads to its detec- 

 tion even at a distance. Such hills are generally of a 

 conoidal shape, but whether characterized by this remark- 

 able form or not, they are bounded by a smooth flowing 

 outline, rarely disturbed by the breaks and asperities so 

 generally characteristic of mountains of micaceous schist. 

 They are generally also covered in the steepest parts with 

 heaps of fragments, on which no soil seems ever to accu- 

 mulate; and as they undergo no decomposition, their 

 nakedness and predominant white colour are seldom con- 

 "cealed even by the growth of a lichen. It is from this 

 whiteness, often so dazzling in the sunshine as to emulate 

 at a distance the effect of snow, as well as from their 

 forms, that the composition of these mountains can often be 

 conjectured. The accumulations of fragments render them 

 also very difficult of access, and, in many places, preclude 

 it altogether, without a degree of labour and risk which 

 few are willing to undertake. Although these ruins 

 bespeak the degradation of the strata, the disintegration 

 of the rock is every where scanty ; the soil which covers 

 these mountains being consequently thin, and consisting 

 of little else than sand mixed with a portion of the black 

 earth that results from the decomposition of vegetables. 

 Hence they form the most sterile of all the soils which 

 Scotland possesses ; and the same character indeed ap- 

 pears to belong to this rock wherever it has been observed. 

 Where the sheep and the stag find little pasture, the 

 botanist will also find but few plants to reward his labours. 

 The indestructible nature of most of the varieties of this 

 rock, and the apparently eternal durability of those which 

 consist of quartz alone, point it out as adapted for archi- 

 tectural purposes, although hitherto neglected. In many 

 situations, as in Isla and Jura, it is of easy access ; and, 



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