IS Mr. Macgillivray on the Granite of ' ^ 



but tarely, and in general present a tendency to the crystalline ar- 

 rangement, the irregular prisms being transverse to the direction of 

 the vein. 



Ben-na-muic-dui (the mountain of the black hog,) consists of ^ 

 huge rounded mass, said to be 4300 feet high, which, on the wes- 

 tern side, towards the summit, presents a corry (or semicircular 

 hollow) formed by a range of precipices, the rocks of which are 

 marked by nearly perpendicular fissures, with transverse rents, long 

 slopes of debris running from their base into a small lake, named 

 Lochan-uaine (the green lakelet,) the waters of which are singu- 

 larly clear, and have a blueish-green tint, which produces a remark- 

 able effect as contrasted with the ordinary tints of the Scottish 

 lakes. On these precipices, as well as other parts of the moun- 

 tain, patches of snow remain unmelted during the summer and 

 autumn. 



On the eastern side, the mountain, from a broad, rounded, 

 and, to a great extent, nearly flat summit, slopes irregularly to- 

 ward the head of Loch Avin, terminating in a magnificent range of 

 precipices. The rocks at the head of this lake are divided by tw6 

 wide rents into three great masses, which present nearly perpendi- 

 cular faces to the lake. These rocks appear to be from three to 

 eight hundred feet high, and exhibit a tendency to the columnar 

 structure. The fissures in two of them are perpendicular, with 

 transverse rent^; in the other, inclined at angles of from 45° to 

 near the perpendicular. There is no stratification, although the 

 perpendicular, and sometimes pretty regular fissures, and, on th^ 

 other hand, the cracks or clefts at right angles to these fissures^ 

 might lead a superficial or prejudiced observer to fancy the exis- 

 tence of strata. These masses bear a striking resemblance to many 

 greenstone rocks, but have a coarser aspect, owing to the disinte- 

 gration of their surfaces, which leaves them rugged and granulated, 

 ^nd destitute of vegetable incrustation. Toward the top they are 

 much broken, and the irregular columns there separate into transi 

 verse tabular masses, disintegration having taken place so as to 

 form parallel fissures, and the uppermost plates lying quite loose; 

 The great rents between the masses, exhibit along their sides co* 

 lums and obelisks^ of various forms, resembling ruins, and aflford 

 beds to the torrents which have carried the debris toward the lake 

 -in the form of long reddish stripes. 



Toward the right of these precipices, when one faces them, the 

 mountain is seen descending toward the lake in a broad slope of 

 bare granite, which has sufiPered little disintegration, or at least iS 

 at present encumbered with few fragments. A torrent which 

 rushes along this slope, is full of blocks and stones toward the 

 bottom. 



Some of the blocks which have fallen from the precipices are of 

 enormous size. One of them, probably ten yards in diameter, has 

 settled so as. to leave a large cavity beneath,- which the shepherds 



