The whole southern part of Arran forms a field by itself, and whatever may be the deeper connections of the agencies that have fashioned the north and the south of the island, the result is a trappean area to the south, as distinct as if it lay in another hemisphere from the north, with its granitic nucleus, and encompassing rings of stratified rock.
This district is little visited, and is almost, if not quite, undescribed; it presents, however, much beautiful scenery, and for the geologist, problems of extreme difficulty and interest, which deserve more attention than they have got.
It may be divided into two belts of tilled land and moorland, above which are the hill tops. This division corresponds roughly to three regions, the lowest chiefly of sandstone, the middle where felstone prevails over the sandstone, and the highest of greenstone.