on Qttartz Rock, 273 



Further Observations. 



[Read 20th December, 1816.] 



For the sake of rendering somewhat more complete the history 

 of this substance, I shall here subjoin an account of a considerable 

 body of it which is to be seen in a very unexpected situation in 

 Sky. Although it will be found mentioned in the present volume, 

 in a supplementary paper on that island, it will not be irrelevant to 

 describe it in somewhat greater detail here. 



A series of stratified rocks is found extending from the Kyle 

 ric'h, on the eastern side of this island, to Loch Eishort, on its 

 western side, and occupying a considerable space laterally, or con- 

 sisting of a frequent repetition of the substances which constitute 

 it. While the nature of these strata, which present alternations 

 of red sandstone with graywacke schist, and with indurated grey 

 and blue granular quartz, would incline us to rank them among 

 the secondary rocks, some doubt is thrown on that conclusion in 

 consequence of the peculiar relation they bear to the older rocks 

 which they follow, the gneiss, and the micaceous and chlorite schists. 

 But I must refer to the paper on Sky itself, for the history of these 

 strata, and limit myself to the description of the particular rock 

 which is the object of this note. 



It forms a large mass of strata in an erect position, running 

 parallel with the red sandstone and the graywacke schist, which, in 

 repeated alternations, lie on each side of it. These strata, always 



