Mineralogy of Sky. Si 



juncdons. These are the only detached masses, the remainder of 

 the stratified trap forming one continuous mass, occupying the 

 limits already referred to. It would be an endless toil to follow 

 the varieties of this rock in the narrative as 1 did in the examina- 

 tion, as fatiguing to the reader as the writer, and equally useless 

 either in a topographical or geological view. After describing such 

 of its connections with the secondary strata as can be discovered, 

 I shall content myself with enumerating a few of the most leading 

 varieties, particularly such as add any illustration to the history of the 

 rock, and with describing the localitiesof the most remarkable strata. 



The contact of the stratified trap with the secondary rocks 

 is seen very frequently on the eastern coast, as well as on the 

 western shore of Loch Snizort, but it never occurs between Dun- 

 vegan head and Soa. In speaking of the secondary strata, I have 

 already mentioned the most remarkable points where these contacts 

 are visible, and need not therefore repeat them : they are most ac- 

 cessible in the neighbourhood of Duntulm, and from Portree north- 

 wards the alternations can be readily traced. I observed nothing so 

 particular at the junctions in any place as to require a detailed de- 

 scription, except the contact of the basalt at Duntulm Castle, with 

 the siliceous schistus, which I shall describe hereafter. 



Among the numerous species of the trap family here existing, 

 basalt is the most conspicuous, and it occurs almost every where, 

 alternating in an irregular manner with all the other species or va- 

 rieties. It is most frequently amorphous, displaying at the same 

 time so great a variety both in its natural mode of breaking, in its 

 external appearance on weathering, and in its texture and colour, as 

 to form a great number of subordinate varieties much more re- 

 markable in their natural situations than when broken into hand 

 specimens. At Talisker it is found perfectly black, and of an ex- 



VoL. III. H 



