Correspondence. . 521 



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GREAT TRAP-DYKES AND REMAINS OF AN ANCIENT FOREST 



IN SKYE. 

 To the Editor of the Geological Magazine. 



Sir, — Having just returned from a trip in Skye, there are two 

 points I wish to draw the attention of your readers to. The ancient 

 forest of the Highlands and the great trap-dykes of the district. 



You favoured me last year with the insertion in. your Magazine 

 of my views respecting the ancient forest. I subsequently found 

 them, in great measure, conj&rmed by Mr. Geikie. I sought in vain 

 in the peat-bogs of Skye, in the Sligachan district, amongst the 

 CuchuUin Hills, for remains of this forest ; but found them beauti- 

 fully exhibited at Kyleaton.' It is everywhere hidden under beds of 

 peat, vmtil the peat-diggers expose them; then the stools are seen 

 standing up two to three feet high, so hardened by the action of bog- 

 water, that vain is the attempt to cut them, and, as a rule, they are 

 left behind, rooted in the gravel in which they grew — the gravel- 

 bed of Scotland — here covered up with that interloper peat, in which 

 no trees can live. I am therefore confirmed in the view before 

 expressed, that the destruction of the ancient forest is owing to 

 climatal changes of great antiquity. I was desirous of ascertaining 

 the species of fir to which these stools belong. At last the quick 

 eye of my brother, a botanist, saw the cones spread around two of 

 the stools ; the peat had preserved them as it preserves the wood, 

 and the roots of bog-plants ; they expanded, in drying, like recent 

 cones of Scotch fir. I could discover no difference between them 

 and recent Scotch fir, and therefore consider the trees were of the 

 indigenous conifer of Scotland, now existing. There seems no 

 reason why they should not be preserved in localities where peat 

 did not grow, or where they were not exposed to the violence of 

 the western winds. 



Skye, like all other Islands of the western sea of Scotland, as 

 shown by Sir E. Murchison's sketch-map, is chiefly composed of 

 eruptive rocks, which consist of two kinds, the more considerable 

 and ancient, due to that great development which raised the 

 CuchuUins greater hills 3,200 feet at Scuir-na-Gillean, and the much 

 later, or trap-dykes. The first of unknown primeval age, to which 

 we may assume we owe the earliest elevation of the land above 

 the sea ; which lifted mountain ranges as well as the younger 

 strata, modified by denudation of the ocean, and no doubt since 

 moulded by atmospheric agencies. These major mountains of Skye 

 are composed of what is called Hypersthene, and are distinguishable 

 from others by their hardness, and by their aiguille points, which 

 nothing alters. They throw down no debris from age to age, but 

 shoot off the rains of the Atlantic at once, as from the roof of a 

 house. The flanks of Scuir-na-Gillean present the appearance of 



1 Kyle-Rhea, or Kyle Akin ? — Edit. 



