Page:A Treatise on Geology, volume 1.djvu/194

 178 Lough Earn and Lough Allen, Monaghan, Dungannon, Newcastle, the counties of Clare, Kerry, and Limerick, about Cashel and Kilkenny, is not very considerable, nor is the coal of good quality. The Kilkenny coal is nearly pure carbon. A great part of the space in the interior of Ireland within its mountain border, Kerry, Mayo, Galway, Donegal, Down, Cavan, Wicklow, Carlow, Wexford, is filled by mountain limestone. (Mr. Griffith's map.)

In Scotland the mountain limestone is, on the contrary, very slightly developed, in connection with the large coal field which stretches from St. Andrews to Ardrossan, and from Haddington to Ayr, filling large spaces in the valleys of the Forth, Clyde, Ayr, Irvine, &c. (M'Culloch's map.)

The mountain limestone formation occupies an immense tract in Northumberland, Durham and Yorkshire, from which country it runs out in a curve, to encircle on the north, and partially on the south, the group of Cumbrian slate mountains. It also appears in great force in Derbyshire; ranges through Flint and Denbigh, to St. Orme's Head and Anglesea; shows slightly round the Clee Hills in Shropshire; and presents picturesque cliffs on the Wye, near Monmouth. There is a long belt of mountain limestone on the north and east sides of the coal fields of South Wales, from Narberth by Abergavenny to Caerphilly; and it is prolonged on the south side by Bridgend, Swansea, and Tenby, to Milford Haven. Detached masses of limestone appear about Bristol, and in the Mendip Hills, and, according to Messrs. Murchison's and Sedgwick's recent researches, the limestones of Barnstaple are classed in the same series.

The carboniferous limestone is supposed to occur in a narrow band below the coal formation of the Clee Hills, arid this is probably the correct explanation of the phenomena visible under Knowle Hill, at Orelton, &c.: but we must call attention to the fact that the white