old red sandstone and partly by coal sandstones, beds of carboni- 

 ferous limestone and of coal and coal shale being interposed amid 

 the beds of the latter. The band of slate is of considerable breadth 

 in this northern ridge, but narrows very much on approaching 

 the opening of Glen Sannox; along the hill sides southward, by 

 the base of Ciod-na-Oich, and above Corrie it is extremely narrow, 

 apparently only a few yards in some places. Still farther south, 

 as it sweeps round south-west between Maoldon and the base of 

 Goatfell, it gradually widens presents bold precipices on both 

 sides of the lower part of Glen Eosa, and along the south border of 

 the granite nucleus between Loch Ghnuis, Dugarry, and Imochair 

 attains its greatest development. Here the thickness of the slate 

 band between the granite and old red sandstone cannot be less than 

 2,000 or 3,000 feet ; whereas above Corrie, in the bed of a stream, 

 we noticed a spot where it is not more than ten feet, so close to the 

 outer margin has the remarkable outburst of granite taken place. It 

 has indeed been asserted by one -writer, and repeated by others, that 

 the continuity here is entirely broken, and that the granite is in con- 

 tact with the old red sandstone. This we consider is decidedly a 

 mistake. In frequent summer rambles along these romantic hill 

 sides, we have examined carefully every open section, and have never 

 seen such a contact. In the spot referred to, the rock is a hard 

 bluish-gray, flinty slate, very like a hard sandstone when taken wet 

 from the burn. The strata here come against the granite end-on, 

 or nearly at right angles. The prevailing dip of the slate over the 

 whole district is the same as that which it maintains in adjoining 

 tracts beyond the limits of Arran, namely, south or south-east at a 

 high angle ; it is not arranged in mantle-shaped strata around the 

 granite nucleus, but is inclined towards it in some places, and off 

 from it in others. Thus along the north side of the nucleus from 

 North Sannox to Catacol, the dip is south or towards the granite, at 

 angles varying from 65 to 75. This is of course unconformable 

 to the granite centre ; but a like dip and inclination on the south 

 side give conformability ; and here, accordingly, from Maoldon by 

 Glen Eosa and Dugarry, and perhaps even as far as Thundergay, the 

 slate is seen to recline against the sides of the granite mountains in 

 a kind of mantling stratification. In many spots there is great con- 

 tortion and irregularity, indicating the operation of violent forces, 

 attendant on the upheaval of the granite. Reference will again be 

 made to several of these cases, as well as to local variations in the 

 mineral character of the slate. 



46. Within the granite tract, whose limits are defined by the 



