Page:A Treatise on Geology, volume 1.djvu/176

 160 whole fauna of the middle palæozoic period. Mantell has recently described a batrachian? reptile (Telerpeton Elginense) from these strata, and eggs of the same group are reported from the old red shales of Forfarshire.

Geographical Extent.—It is in Scotland that the old red formation is thickest, most varied in composition, and most extensively distributed. It ranges on the N.N.W. coast in interrupted patches from near Cape Wrath to Loch Carron, Skye, and Rum; on the N.E. it forms a large surface in Caithness, skirts the Dornoch and Moray Friths, passes up the great valley to Meal Favournie, and spreads by Nairn and Elgin to the Vale of the Spey. A large belt of red conglomerates borders the Grampians, from Stonehaven to the islands in the lower part of Loch Lomond, and occupies much of the sea coast to the Frith of Tay. Red sandstones border the northern flanks of the Lammermuir hills, expand in the Vale of Tweed, and margin the slate tracts of Dumfriesshire and Kirkcudbright. Arran, Bute, Cantire, and the coast about Largs and Ardrossan show the same formation.

In England the old red sandstone sometimes appears associated by alternation of beds with the lower part of the mountain limestone series, especially on the eastern border of the Lake district about Penrith. Its conglomerates appear at the foot of Ulswater, and in valleys about Kendal, Kirkby Lonsdale, and Ulverston. It is enormously developed, and acquires more variety of composition in the counties of Hereford, Monmouth, Brecon, Carmarthen, and Pembroke; and is slightly exposed in connexion with the limestones of Mendip, Bristol, and Wickwar.

The old red changes its character, but occupies a large space, on the southern coast of the Severn, and again in a parallel course along the shore of South Devon. Devonian rocks appear in the Eifel, in the