GEOLOGICAL FORMATION 65 



waters, in time of flood, by this deposit through which it 

 grooves its channel. 



Superficial Deposits. The principal of these are: (1) 

 Raised Beach Deposits, (2) Boulder Clay, (3) Peat, 

 (4) Alluvium, and (5) Blown Sands. The most fertile and 

 easily worked soils in the island originated from raised 

 beach deposits laid down at the time when the sea over- 

 flowed the land to various levels at and below the 100-feet 

 contour. Though the soils are usually of a light stony 

 nature, they yield good crops. The arable land of 

 Balanahard, Port - an - Tigh - mhoir, East Kiloran, Lower 

 Kilchattan, Machrina, Ardskenish, Garvard, and some other 

 places, as well as Oransay, are of this character. Boulder 

 clay is expensive to work, but with good drainage and 

 tillage yields good crops. The principal areas of it are West 

 Kiloran, Upper Kilchattan, Laon Airidh, West Scalasaig, 

 and Balaromin-dubh. Much of the low-lying land, mostly 

 meadow, such as Kiloran meadows and the low ground 

 bordering Loch Fada Blar-an-Deabhaidh, Leana-ghlas, etc. 

 is composed of peat. Unless well looked after in the 

 matter of drainage and top-dressing, grass in these meadows 

 is apt to die out and be replaced by less nutritious 

 plants, such as the Jointed Rush (Frafann), sedges, mosses, 

 and others of a semi-aquatic nature. The principal areas 

 of alluvium to be met with are the low-lying parts of Fang 

 in Kiloran, Leana-na-Cachaleith in Kilchattan, and Moine 

 Thomach in Scalasaig. Tracts of blown sand, irregular and 

 billowy in outline, are to be seen in the north and south 

 ends of the island. 



Over most of the hilly land there is a layer of peat, of 

 some depth in the hollows, becoming thin towards the tops 

 of the hills, and frequently allowing bare rock to be exposed 

 on the summits. That the peat layer is gradually increasing 

 in depth may be observed in the peat-cutting areas, where 



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