316 SKY. GEOLOGY. SECONDARY STRATA. 



The map will show that the small island Fladda lies at 

 the boundary of the strata on this shore. Hence, all round 

 the points of Aird and Hunish, the trap descends to the 

 edge of the water, which thus excludes from view whatever 

 may exist beneath it. Near Duntulm, the strata appear 

 again ; occupying however but a small extent along this 

 shore, and exposing but a very thin edge. The prevalent 

 alternations on this side of the promontory, consist of 

 thin beds of limestone with shales of different colours 

 and of different degrees of hardness, verging to siliceous 

 schist, and interspersed with rare beds of a coarse sand- 

 stone that occasionally contains, like some parts of the 

 limestone, fragments of carbonized wood. The organic 

 remains found in these beds are the same as those last 

 mentioned on the eastern shore ; and, with the other 

 circumstances already enumerated, confirm the view 

 originally held out respecting the dip of the strata of 

 Trotternish, by proving that these are the uppermost 

 beds of the series. It is thus at the same time proved, 

 that the shale also appertains to the upper parts of the 

 deposit ; a circumstance indicated by the frequent occur- 

 rence of this substance on the surface of the interior 

 country. 



It is now necessary to examine the last remaining 

 portions of white sandstone that are found in Sky, which, 

 if they do not possess a more intimate geological con- 

 nexion with the gryphite limestone than those of Trot- 

 ternish, are at least more nearly associated with it in 

 geographical position. They are found in two places 

 only, forming a small part of the point of Swishnish and 

 a much more considerable portion of the promontory of 

 Strathaird.* 



The deposit that occupies the former situation rises 

 into abrupt cliffs about sixty feet in height, and may 

 be examined from the sea, although with some difficulty ; 



* Plate XIV. fig. a. 



