

LUNGA. GEOLOGY. 1 6.5 



termingied with other schistose substances which will 

 also be found to alternate with them throughout the 

 whole southern course of the same strata in the remainder 

 of this chain. The general direction of these strata 

 in Lunga, corresponds with that of its eastern shore ; 

 the bearing of which however, as laid down in the 

 large map of Scotland, is not coincident with that di- 

 rection. It is north, or somewhat more easterly, subject 

 to that slight occasional flexion which prevents it from 

 being determined accurately by observations taken at 

 any single place. It will be found to correspond very 

 accurately with the bearings of the strata _in Scarba, 

 and in the northern extremity of Jura; but deviates 

 by two points, or somewhat less, from those of the 

 southern portion of this latter island, as well as from 

 their apparent prolongation through the eastern division 

 of Isla. It differs by the same quantity from the bearing 

 of the strata of the neighbouring islands on both sides ; 

 namely, from Seil and the northern part of Luing 

 on the east, and from the Garveloch islands on 

 the west. With the southern division of Luing, the 

 correspondence is more exact. The dip is the same 

 as in those islands, eastward; and it will hereafter be 

 seen that this is the predominant one throughout the 

 whole chain to the southward. The quantity of the 

 inclination corresponds also with that of the strata in 

 the islands already described ; vacillating between 20 and 

 60, but so that 40 may perhaps be taken as the pre- 

 dominant one, both in this island and Scarba, as well 

 as in the northernmost parts of Jura ; among all which it 

 is scarcely possible to discover any geological distinction. 

 The argillaceous schist forms an irregular ridge on 

 the eastern shore ; occupying a very narrow space when 

 compared with the quartz rock, which extends over 

 the highest parts and by far the largest portion of the 

 island. Its dimensions are irregular, because the in- 

 dentations of the shore undulate on each side of the 



