1 44 THE CRUISE OF THE BETSEY ; OR, 



lie widely apart. The red rocks we find laid down in most 

 of our maps as Old Red, though I am disposed to regard them 

 as of a much higher antiquity than even that ancient system ; 

 while the bluish-gray rocks are decidedly Liasic. * The cove 

 between represents a deep ditch-like hollow, which occurs in 

 Skye, both in the interior and on the sea-shore, in the line of 

 boundary betwixt the Red Sandstone and the Lias ; and it 

 " seems to have originated," says M'Culloch, " in the decom- 

 position of the exposed parts of the formations at their junc- 

 tion." " Hence," he adds, " from the wearing of the mate- 

 rials at the surface, a cavity has been produced, which becom- 

 ing subsequently filled with rubbish, and generally cover- 

 ed over with a vegetable soil of unusual depth, effectually 

 prevents a view of the contiguous parts." The first strata 

 exposed on the northern side are the oldest Liasic rocks any- 

 where seen in Scotland. They are composed chiefly of green- 

 ish-coloured fissile sandstones and calciferous grits, in which 

 we meet a few fossils, veiy imperfectly preserved. But the 

 organisms increase as we go on. We see in passing, near a 

 picturesque little cottage, the only one on the shores of the 

 bay, a crag of a singularly rough appearance, that projects 

 mole-like from the sward upon the beach, and then descend- 

 ing abruptly to the level of the other strata, runs out in a 

 long ragged line into the sea. The stratum, from two to three 

 feet in thickness, of which it is formed, seems wholly built up 

 of irregularly-formed rubbly concretions, just as some of the 

 garden-.walls in the neighbourhood of Edinburgh are built of 

 the rough scoria of our glass-houses ; and we find, on exami- 

 nation, that every seeming concretion in the bed is a perfectly 

 formed coral of the genus Astrea. We have arrived at an 

 entire bed of corals, all of one species. Their surfaces, where- 

 ever they have been washed by the sea, are of great beauty : 



* Sir R. Murchison considers these rocks Sihuian. See "Quarterly 

 Journal" of the Geological Society, Anniversary Address. 



