264 ACCOUNT OF THE MINERALOGY 



ance. Some such lines existed in this cliff ; which, near the dyke, 

 were drawn as it were into the curves it has described, which 

 could not easily have been the case, had the rock been in a so- 

 lid state when it was traversed by this dyke. 



The soil produced by the degradation of trap-rocks is usu- 

 ally found to be fertile, and favourable to vegetation. These 

 islands, however, where no other rocks exist, have no such 

 happiness to boast of. In Faroe, there is no flat land, on 

 which the reduced materials can rest ; and where not occu- 

 pied by impracticable cliffs, they present a solid smooth sur- 

 face, always highly inclined, on which vegetation, by degrees, 

 arrests the crumbling particles, and in time forms a sward 

 upon the arid rock. Here, however, from the impenetrable 

 nature of the mass, no support can be obtained by the vege- 

 table fibres ; accumulation, therefore, becomes fatal, and, sink- 

 ing under its own weight, the soil slips from the surface, and 

 leaves the rock in its original naked state. 



The hills being placed so near to each other, there are no 

 valleys to enrich ; consequently, whatever falls from above, 

 is swept away by the mountain torrents, and affords no far- 

 ther benefit. So slight is this vegetable covering, that it often 

 gave way under our feet, leaving the smooth rock exposed. 

 This was likewise the case among the more recent debris, 

 on which, when expecting safe footing at least, we often found 

 an inclined and slippery surface, covered with wet clay, which 

 rendered a considerable degree of caution necessary.. It is be- 

 tween the sward thus formed and the rock, that the rain- 

 water must find its way. Hence the cold damp bottom on 

 which the verdure rests, renders it totally unfit for cultivation 

 or improvement. 



Where the torrents poured down the side of a hill, we had- 

 an opportunity of observing the smooth and solid nature o£ 



the 



