Page:A Treatise on Geology, volume 2.djvu/73

 CHAP. VI. amidst the mountains of Westmoreland (as in a small hollow between Kirkby Lonsdale and Kendal) and Scotland (as at the head of Glencoe), trees, rooted or prostrate, occur mixed with peat; but it is on the shores, or in the midst of the alluvial plains of Yorkshire, Lincolnshire, Cambridgeshire, West and East Norfolk, Cornwall, Somersetshire, Swansea, Cheshire, Lancashire, the mouths of the Clyde, Forth, and Tay, the shores of the Orkneys and Hebrides, that the most abundant of these buried forests occur. This general fact justifies the title of Submarine Forests, commonly applied to them, and is of great importance in reasoning on the circumstances of their accumulation. On the contrary, the greater part of the Irish bogs are inland accumulations; but they occupy the lower plains of the country, and are often margined by gravel banks, and abound on the line of the Shannon, which is a stream of very little declivity.

The trees contained in these deposits are identical with those now growing in the vicinity, hazel branches and nuts being very common; with them are occasionally found fluviatile or lacustrine shells, and bones of deer and other land animals; but, as far as we know, no marine mollusca, and seldom marine remains of any kind. The level of the buried trees is seldom above, but generally below, the high-water line, and often level with, or not infrequently many feet, or even yards, below, low-water. On the sides of the Humber, below Hull, submarine peat and trees are found at various depths below low water; at the mouth of the Tay, level with it; at Swansea and Owthorne, sloping beneath it; at Sutton, near Alford, on the Lincolnshire coast, visible only at the lowest ebb-tides.

As De Luc suggests, with regard to the layers of peat resting on clay at Rotterdam (Hist. de la Terre et de l'Homme, tom. v. p. 325.), we may believe the deep buried trees and peat of the sides of the Humber to have been drifted; but this is not the explanation generally proposed by observers, who appear almost without exception