440 Proceedings of the 



The isle of Seil, which is about three miles in length by 

 two in breadth, is described by this geologist as consisting of 

 beds of argillaceous schist, with a bearing N.E. by N., and a 

 dip to E. On the north-west is an elevation of trap-rocks, of 

 the same kind as prevails throughout the large island of Mull, 

 the surrounding smaller isles, and the mainland of Lorn, Ar- 

 gyleshire. The argillaceous schist occupies the middle and 

 greater portion of Seil ; and towards the east is succeeded by 

 a grayish stratified rock, which is composed of a conglomer- 

 ate of felspathic and hornblende rocks ; to this, again, suc- 

 ceeds the same argillaceous strata as in the centre. On the 

 north-west point of the island is a patch of red sandstone, 

 similar to that which prevails in Kerrera and the Mainland. 

 The small isle of Eisdale consists of the same roofing-slates 

 as those of Seil. In March of the present year (1858). while 

 the quarrymen were at work in the slate quarry in the centre 

 of Seil, about 140 feet below the surface, on turning up a 

 large block of limestone, which had previously been detached 

 by blasting with gunpowder, they noticed a sort of break or 

 crevice in the rock, and a slight coating of unctuous clay all 

 around it. A detached mass from the crevice, of a few inches 

 in length, excited their curiosity from its lightness ; and on 

 washing it, they perceived that it was a coaly mass. Such 

 are the words of a statement by the intelligent superintendent 

 of the quarries, Mr Whyte, to whom, on his arrival at the 

 spot, the workmen delivered the coaly matter, and pointed out 

 to him the place where it had been found. 



Specimens of the clay-slate, limestone, and coal, were sent 

 to me through Dr Thomson, the medical gentleman resident 

 on the island. The schist is the common small-grained roof- 

 ing-slate described by Dr Macculloch. The greyish limestone, 

 which freely effervesces in hydrochloric acid, appears also 

 identical with the " grey limestone slate" of this geologist. 

 The coal has all the external appearance of ordinary glance- 

 coal ; it burns with a bright flame, and leaves a cinder. Un- 

 der the microscopical manipulation of MrEryson, it distinctly 

 indicates a " vegetable cellular structure, resembling the fu- 

 coid forms of vegetation." The presence of distinctly vege- 

 table matter, having all the properties and appearances of coal, 



