EGG. GEOLOGY. 513 



and rarely attains a thickness of two inches ; more com- 

 monly it varies from a quarter to half an inch, many 

 laminaB often succeeding each other in a small space. 

 Some of the specimens present that ramified appearance 

 of the fibres which bears so strong a resemblance to 

 organic arrangement, and it is scarcely necessary to add, 

 that the fibrous crystallization is perpendicular to the 

 plane of the beds. Among the calcareous strata are 

 found many other varieties. Some are bituminous and 

 fetid, others contain so much sand as to pass at length 

 into calcareous sandstone, while in a third, are found 

 carbonized vegetable fragments, and in a fourth, shells, 

 It is so difficult to procure distinct specimens of the latter 

 and at the same time to mark the beds from which they 

 were derived, that I shall not pretend to describe the 

 organic remains, nor do I indeed imagine that they are 

 any where in a state to admit of being ascertained. The 

 only distinct specimens which I could procure contain 

 a small shell resembling a terebratula, but still deficient 

 in the minute parts by which alone its genus could be 

 determined. I may however remark, that they are so per- 

 fectly identical with those of the upper beds of Trotternish 

 in Sky that they cannot be distinguished on comparison. 



Among the sandstone also, are two varieties particularly 

 requiring notice. One of these contains thin laminae and 

 fragments of coal ; alternating, like many others of the 

 lowermost beds of this rock, with some of the calca- 

 reous strata. It is among these alternations that those 

 mixtures of calcareous and sandy matter are to be seen 

 which may either be called calcareous sandstones, or 

 siliceous limestones, as either substance happens to pre- 

 dominate. But here, as in the calcareous strata, it would 

 be an useless task to enumerate all the variations which 

 occur, and I shall therefore conclude by describing one 

 of the most remarkable of these sandstone beds, although 

 not peculiar to this place, since it occurs in Sky and 

 in Rasay, and is moreover not unfrequent in other situa- 



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