366 ON THE HIGHLANDS. 



mity of its position, and on the circumstance al- 

 ready noticed, that layers or strata of the same 

 material, but of a smaller size, are found in the 

 lower part of the Glen, alternating regularly with 

 the usual strata of the district. 



It rarely happens, that a philosophical opini- 

 on, however uncommon, cannot appeal to some 

 phenomena of nature, as seeming to give it the 

 colour of truth, The great bed, by which Glen- 

 Tilt is thus distinguished, has been quoted as a 

 demonstration of the ingenious hypothesis, which 

 ascribes the consolidation of the principal sub- 

 stances in the mineral kingdom, to the action of 

 heat variously modified. That the melted rock 

 had invaded the country, and been introduced into 

 the adjacent shistus, from the bowels of the earth, 

 is assumed as an undeniable fact, without even 

 the form of illustration. A fertile imagination, 

 it is true, might figure the mass, as it strikes the 

 eye, viewing it from the bridge above the Lodge, 

 to have been once in fusion, floating fragments of 

 the neighbouring rocks. The argument, how- 

 ever on this ground, is altogether equivocal, since 

 fragments must have been found in beds and veins, 

 whether they were formed by deposition from 

 above, or by igneous projection from below. — It 

 must also be observed, that a more careful oryc- 

 tognostical examination, satisfactorily proves, that 

 many substances mistaken for fragments at first 

 view, are really of cotemporaneous formation with 

 the including rock. This observation applies 



