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GEOGNOSY OF THE ISLE OF EIGG 



BY 



R. J HAY CUNNINGHAM, Esq. M.W.S., &c 

 (Read gtk March 1839 J 



Eigg, which is about seven miles from the mainland at Ari- 

 saig, exhibits examples of both the stratified and unstrati- 

 fied classes of rocks ; all of which agree in the great de- 

 tails of relative position, mineral characters, and organic 

 contents, with phenomena observable in Morven, Skye, 

 Mull, and several of the smaller islands which skirt this 

 part of the west coast of Scotland. Speaking generally of 

 the structure of Eigg, it may be described as a mass of 

 trap which rises through, overlies, and sends parallel veins 

 into, an alternating system of oolitic sandstone, limestone, 

 and shale. When viewed from the sea, all the rocks of 

 the Island exhibit a very distinct dip to the south. Thus 

 the rock which, on the northern extremity, occurs at the 

 surface and several hundred feet above the sea, sinks into 

 it at the other ; the angle at which the several strata are 

 inclined being so small that it is hardly discernible if the 

 observer is in their immediate vicinity. At no great dis- 



