EXCURSION II. 79 



reach, and of the " cottage homes " nestling amid groups of 

 trees, in shelter of the hills and sloping banks which enclose 

 the smiling fields of Brodick plain. Often as we have come 

 to the edge of the ridge by this route, we have always felt 

 the same delightful surprise when the scene first burst 

 upon us. 



41. This ridge consists chiefly of sandstone. Trap rocks 

 form a thin capping along its highest part ; they extend a 

 little way down the southern slope, thickening as they 

 descend, but along the highest ridge are so thin that sand- 

 stone occupies in some places depressions in the ridge ; and 

 the trap occurs only on the isolated tabular knolls into which 

 the ridge is cut up, especially towards the west. The trap 

 consists of felspar and augite mainly, with imbedded zeolites. 

 MacCulloch designates it augite rock ; but hornblende and 

 iron also occur. The sandstone close to its junction with the 

 greenstone of the summit is highly metamorphic, resembling 

 a quartz rock. Along the steep northern front also, west of 

 Dun-Dhu, beds of clinkstone crop out in various places, at 

 different heights. These are either of truly igneous origin, or 

 are metamorphic sandstones, altered by whin dikes, of which 

 there are several, or by the near proximity of the great 

 igneous masses greenstones, porphyries, and pitchstone 

 which pervade the sandstone in this quarter. The association 

 of these various products affords one of the most interesting 

 sections to be met with in Arran. It is best exhibited a 

 little to the west of the path which leads down from Dun-fion 

 to the farm-houses. Dun-fion, or Fingal's Fort, is the high- 

 est point on this portion of the ridge, right over Corriegills 

 shore, and 500 to 600 feet in height. A low mound, enclos- 

 ing an elliptic space 40 yards by 16, is seen round the 

 summit, but nothing whatever is known of the history of the 

 fort. From traces of vitrification said to have been noticed 

 on the stones of the mound, it has been conjectured that the 

 place was the site of a beacon fire, in the wild old times, as 

 well as a stronghold. We were unable, however, to find the 



