362 SKY. GEOLOGY. OVERLYING ROCKS. 



are still more trifling, while in most cases they are either 

 overwhelmed or cut off by trap, so that they cannot 

 be pursued for any continuous space. Their thickness 

 rarely extends to a few inches, and they are found alternat- 

 ing dispersedly with shale and sandstone over different parts 

 of the surface of Trotternish. Among other places where 

 they are visible I may name Loch Uig, and the waters 

 of Leolt, Grocheard, and Grimset. Some attempts have 

 been made to examine them in these places, but without 

 attaining more information than is communicated by 

 their casual display. The appearances are both too 

 obscure and too rare to enable the nature and extent 

 of the coal to be ascertained through such a country 

 as this ; nor is it likely that any further expense will 

 be bestowed on a pursuit so discouraging. It is probable 

 that wherever this mineral appears, it is like that found 

 among the corresponding strata in Egg, very thin and not 

 persistent ; but it is impossible to speak with any decision 

 respecting appearances so vague and unsatisfactory. All 

 economical speculations on this subject are therefore 

 superfluous, since nothing but a regular professional 

 investigation could render the condition of this coal intelli- 

 gible or determine its value ; but it may be remarked in 

 concluding this cursory notice, that the connexion of the 

 strata with the trap, such as it has already been 

 represented, seems sufficient to destroy all hopes of 

 success in working it as an object of profit. 



HAVING thus completed the history of the stratified 

 rocks of Sky, I must proceed to the description of the 

 unstratified, of which the general topographic extent has 

 already been sketched. 



To assign the places and describe the characters of 

 all the substances that come under this general title 

 would be impossible; so frequent are the changes, so 

 intricate the mixtures of the several rocks, and so 

 tmdefinable the greater number of the varieties ranked 



