ON THE HIGHLANBS. 



companicd by quartz, which so often occurs 

 throughout the whole of this formation ; and the 

 vein, so far as it is visible, is from one to five 

 inches wide. — Below the mine, the clay-slate in- 

 cludes iron pyrites ; and there is a vein of felspar- 

 porphyry, which traverses the slate, in a direction 

 about 27 P north of east: veins of quartz also, with 

 with copper pyrites, occur. 



It is through this formation of slate, that the 

 River Teath, in forcing its passage from Loch 

 Lubnaig, along the foot of the mountain, has 

 formed the celebrated Pass of Leny, the only ac- 

 cess to the Highlands of Scotland, in this quarter. 

 The scenery here, is well known to be uncommon- 

 ly striking ; and what is remarkable, the action 

 of the water, in scooping out the bed of the river, 

 has at the upper part of the Pass, worn down the 

 mass of the clay-slate, till the strata of mica-slate 

 on which it rested, are laid bare. At a small 

 distance above the water, the clay- slate is found 

 on both sides. The mica- slate in this place, is 

 porphyritic, and so extremely hard, that a neigh- 

 bouring proprietor, wishing to deepen the bed of 

 the river, for the purpose of gaining ground at the 

 upper extremity of Loch Lubnaig, was obliged, 

 after much labour and expence in blowing the 

 rock, to abandon the operation as impracticable. 



On this part of the subject, it is only necessary 

 to remark further, that the clay-slate formation, 

 considered as composing the base and neighbour- 

 hood of Ben-Ledi, extends in a conformable posi- 



