62 COLONSAY 



South of the road, beyond the boggy ground of Rioma-mhor, 

 alternate beds of mudstones and grits run their length 

 through Garvard to the strand, each kind of rock carrying 

 with it its peculiar characteristics of contour, which are well 

 exposed on both sides of the track from Garvard House 

 to Bealach-an-Aircleich. The mudstones rise up in low 

 weathered escarpments on the east side of the path, the grits 

 presenting their rounded forms on the west. Mudstones 

 reappear in Oransay, rising there into the highest hill, 

 Beinn Orasa. The stone has been much used for building 

 the field dykes about Machrins. 



Cutting across the golf-links to the headland of Dun 

 Ghallain, we come to the last of the rock series to be 

 considered the Dun Ghallain green-banded epidotic grits 

 which, except for the mudstones and sandstones, are . the 

 lowest rocks of the Colonsay series. Near the head of Port 

 Lobh the overlying white felspathic grits are readily 

 distinguished from the Dun Ghallain grits by their different 

 structure. The white grits are not as clearly stratified as 

 the green-banded grits. Dun Ghallain grits curve round 

 the south-west of the island from Turnicil to the head of 

 Traigh-nam-Barc, rising there into Cam Spiris, and appearing 

 again in the Cuirn-mhor of lochdar-na-Garbhaird and on the 

 Oransay side of the strand. 



In the north-eastern extremity of the island the relations 

 are more complex. A traverse made from the outcrop of 

 the limestone at Scalasaig to Kiloran Bay passes " first over 

 successively lower beds dipping south-eastwards, and then 

 this dip is reversed and the same series is repeated in 

 ascending order until the Kiloran Bay limestone is once more 

 reached. The anticline thus crossed has a north-easterly 

 trend, and brings to the surface, along its axis, the rocks of 

 the Kiloran and Milbuie groups which underlie the limestone. 

 From the manner in which the limestone circles round 

 Kiloran Bay, it is clear that the latter here occupies the 



