SANDSTONE OF THE WESTERN COAST. 99 



is derived. As this latter rock appears to have been 

 generated from the materials of gneiss and granite, so 

 the former has probably been recompounded principally 

 from the fragments of previous quartz rock, micaceous 

 schist, and argillaceous schists; although the existence 

 of felspar in the former, shows that granite also must 

 have been one of the substances engaged. The beds 

 which present the conglomerated and gray wacke structure, 

 are similar in character in both; but it is unnecessary 

 to enumerate the various points of resemblance which 

 those who have attended to the preceding descriptions 

 cannot fail to have remarked. With respect to the ex- 

 istence of an unquestionably mechanical structure in a 

 primary rock, it may also be remarked that the micaceous 

 schist of Isla, which contains fragments of granite and 

 quartz rock, presents a decided example of it ; as do 

 also those rocks of the gray wacke and conglomerate 

 structure, which are found among the argillaceous schists 

 in various parts of Scotland. If even the red sandstone 

 of this district be considered as a modification of quartz 

 rock, no alteration will follow in the nature of any of the 

 views that have here been brought forward. The same 

 history will be transferred to a new term, not to another 

 substance; and the same consequences will follow that 

 so often result from the substitution of one word for 

 another ; in the best cases, that of leaving e. very thing 

 precisely where it stood before ; and in the worst, con- 

 fusion and obscurity instead of light and order. 



In all the situations hitherto described where this rock 

 is followed by the secondary strata, these have invariably 

 proved to be the conchiferous limestone and the white 

 sandstone which in Scotland succeeds that rock. It 

 became therefore an interesting object of research to 

 discover it in contact with a red sandstone of acknow- 

 ledged secondary formation, and thus it was at length 

 found in Loch Greinord. Here, two small patches of 

 the secondary strata are seen occupying a space not 



