SKY. GEOLOGY. SECONDARY STRATA. 345 



pectines, terebratulre, and other shells found in the inferior 

 limestone having disappeared. 



At Ru na Braddan, beds of common black shale begin 

 to make their appearance, but still in so disconnected 

 a state that their relations to the preceding strata can 

 not be discovered. They appear nevertheless to be 

 superior ; and the position of similar beds on the western 

 shore of this promontory seems to confirm this opinion. 

 I shall refer to a separate place the appearances of coal 

 and of siliceous schist which occur here ; and to the 

 division which treats of the overlying rocks, the nu- 

 merous derangements and irregularities that accompany 

 the intrusion of these. 



The stratified rocks disappear entirely for a certain 

 space near the northernmost cascade formerly described, 

 but are repeated with more or less irregularity as far as 

 Loch Staffin, on the eastern shore of which they finally 

 vanish. The calcareous strata here alternate with com- 

 mon shale, as on the western shore; and, from the 

 statement formerly given respecting their dip, there is 

 reason to conclude that these beds are the uppermost 

 of the whole series. The organic substances that occur 

 among the lower beds, here disappear, and are replaced 

 by others of a different nature- These are in many 

 places so abundant that the whole body of the rock 

 seems an entire mass of shells, belonging apparently to 

 two or three distinct species, but all too imperfect to 

 admit of their characters being determined. It can only 

 be said that they bear a resemblance to ostreae and to 

 terebratulx : there appear also to be remains of some 

 other bivalves, but in such a state as to defy all con- 

 jecture. It is worthy of remark however, that one of 

 the beds, which seems to consist almost entirely of a 

 condensed mass of minute terebratulae, is also found in 

 Egg ; a circumstance which I shall have occasion to 

 notice hereafter. It must be added that beds of fetid 

 limestone are found amonsc these strata. 



