ARRAN. ALLUVIA. 335 



bar, which, by stretching nearly across the bay, affords 

 an excellent inner harbour for boats, where they lie, as 

 in a pond, protected from sea and wind. 



The alluvia in Glen Catcol present a different appear- 

 ance. These form terraces skirting the borders of the 

 river, which seems now to be working its way through 

 materials which it has at some former period deposited ; 

 a phenomenon sufficiently common in the mountain tor- 

 rents of Scotland. Similar terraces are found occupying 

 the narrow mountain glen through which the lorsa runs, 

 but they are here of considerable extent and depth ; much 

 greater indeed than to permit us to attribute their forma- 

 tion to the feeble stream which is now employed in under- 

 mining them, and in carrying their materials forwards towards 

 the sea. The origin of such alluvia, extremely common 

 in the continental land of Scotland, is indeed very ob- 

 scure. A few perhaps may have been deposited in par- 

 ticular situations by the same waters which, under certain 

 progressive changes, are now removing what they for- 

 merly laid down; while, in other cases, it is impossible 

 to assign any mode of action by which this double and 

 opposite effect could have taken place from one agent. 

 In some of these situations, the lateral descent of materials 

 at right angles to the course of the valley and of the 

 main stream, seems to have produced these accumula- 

 tions ; which the action of that stream is daily employed 

 in shaping into the forms so often witnessed in narrow 

 mountain valleys, and so conspicuous near the course 

 of the lorsa. In other cases the quantity and quality 

 of the materials, their extremely rounded forms, the 

 nature and permanence of the hills above, and the want 

 of a regular gradation of size in the stones from the bot- 

 tom upwards, seem to show that other causes, of a tran- 

 sient, and probably of a diluvian nature, have in distant 

 times generated those deposits, which have been sub- 

 sequently acted on by the stream concentrated on the 

 bottom of the glens by the form of the ground. A wide 



