RUM. GEOLOGY. 483 



can readily be discovered by following the most accessible 

 of the strata in the order of their superposition. In 

 treating of Sky, the great thickness of the red sand- 

 stone was noticed, and the same remark may be made 

 on it here, although there is not the same access to 

 it throughout its whole extent, since the lowermost 

 surface is invisible. With much labour and patience 

 a tolerable approximation to the real thickness might 

 here be made, by following the beds slowly along the 

 shores and sides of the hills ; but I kno" w not that 

 any useful purpose would be accomplished by such an 

 estimate. 



From the hill last mentioned, the sandstone continues, 

 first along the northern shore, and subsequently along 

 the north-western, to near the western point of the island 

 at Bridianoch, where it disappears. From the northern 

 and north-western shores, as far as Kilmory, and beyond 

 that, it extends backwards into the country, with charac- 

 ters similar to those which it has near Loch Scresort; 

 forming a range of hills, comparatively low, but rising 

 to the height of at least 800 feet. ' The boundaries, for 

 want of accurate points of reference, cannot be rigidly 

 denned, but the map will give a general idea of its 

 extent. Approaching the western point of the island 

 it occupies considerably less space, and at length barely 

 skirts the shores ; the interior prolongations being con- 

 cealed by the overlying rocks. Its inclination here 

 changes, the angle becoming much greater; while the 

 direction also varies. This alteration is easily seen at 

 Giurdil, where it rises to an angle of forty degrees ; 

 that angle becoming still higher under Scuir more, 

 where this rock at length terminates. The beds are 

 here much traversed and somewhat disturbed by veins 

 of basalt, which in the progress of decomposition have 

 left in them remarkable arches and caves. They are 

 also traversed in the same place by one vein of augit 

 rock, a substance forming a considerable portion of 



