298 GENERAL COMPARISON OF 



of being rectified ; but as these have already been consi- 

 dered in the general remarks on the Trap isles, it is unne- 

 cessary to repeat them. 



The first feature which attracts the eye in glancing 

 over the general map of these islands, is that linear 

 direction of the coasts already pointed out at the com- 

 mencement of this work ; the tendency of which varies 

 between the north and the north-east, maintaining a 

 general conformity to that of the adjoining coasts of 

 the mainland, as well as to the prevailing bearings of 

 the whole western shore of Scotland. From the Mull 

 of Isla to the northern point of Jura, the tendency is 

 more particularly to the eastward of north, as it will 

 also be found on the adjoining coast of Argyllshire, and 

 in the direction of the sea lochs by which this land is 

 intersected. Among the smaller islands to the north of 

 Jura it becomes more northerly, and here also the shores 

 of the mainland maintain a general parallelism with those 

 of the islands. 



These prevailing directions in the shores of the islands, 

 will be found to correspond in a great degree with the 

 directions of the strata of which they are composed, and 

 to vary in a great measure according to the variations 

 of these lines of bearing. A similar general correspond- 

 ence will be discovered on the mainland, between the 

 direction of the strata and the general forms of the shores. 

 There is consequently a regular series of connexions be- 

 tween the insular and the continental strata; the latter 

 being prolongations of the former where they lie in the 

 same line of direction, and succeeding them in parallel order 

 when situated to the eastward. It is not however meant 

 that either the outlines of the islands, or the mountain 

 ridges of the mainland, are always conformable to the 

 directions of the strata. This is doubtless true in many 

 cases, as in Isla and Jura to a great degree, and still 

 more remarkably in the Slate isles. But in Gigha, the 



