324 SKY. GEOLOGY. SECONDARY STRATA. 



with regard to the nature of this connexion. I shall 

 mention the most remarkable examples that I observed; 

 the explanation will scarcely appear till the line of the 

 western shore is described. 



Not far from Broadford a solitary rock is seen, of 

 a character so doubtful that it is difficult to know in 

 what division to place it. Possessing the colours and 

 crystalline texture of the unstratified limestone it is 

 disposed in beds, but of much greater thickness than 

 the ordinary strata where these are regular. On wea- 

 thering it presents numerous cavities, produced by the 

 dropping out of various irregular bodies consisting of 

 a whiter and purer limestone than the base, the crust 

 which united them to the mass of the rock having been 

 destroyed. On a distant view they resemble shells, 

 but the resemblance disappears on a nearer inspection, 

 while the fresh rock shows nothing, on fracture, but a 

 confused assemblage of lumps of different colours. There 

 will hereafter appear reason to think that they have had 

 their origin in organic substances. Returning to the 

 interval between the stratified and unstratified rock near 

 the syenitic hill Ben na Charn, portions of the limestone 

 are found, possessing the general characters of the un- 

 stratified rock; but traversed by parallel planes of a 

 slaty substance much harder than the shale of the strati- 

 fied limestone, and indicating by this obscure appearance 

 of stratification, a community of character between the 

 two. In a similar situation the same limestone is re- 

 gularly interstratified with beds of quartz of the most 

 ordinary aspect, a foot in thickness, and bearing the 

 same analogy to the crystalline limestone which the 

 sandstone formerly described does to the earthy limestone 

 of Broadford. Gradations of character also take place 

 among these quartzose strata; some of them being 

 undistinguishable from the indurated portions of sandstone 

 that occur in particular situations among the ordinary 

 soft sandstones of the latest date. There is yet a still 



