290 Lammermuir Hills. 



If we again examine the Map, we find that a large 

 tract of country, forming great part of the Lowlands, 

 stretches across Scotland from north-east to south-west, 

 including the Firths of Tay and Forth, and all the 

 southern and eastern shores of the Firth of Clyde. 

 This area is occupied by Old Ked Sandstone and rocks 

 of Carboniferous age (Nos. 2 and 3, fig. 55), mostly 

 stratified, but partly igneous. To the south lie the 

 heathy and pastoral uplands known as the Carrick, 

 Moorfoot, Pentland, and Lammermuir Hills, marked 1', 

 which, like the Highlands, are also chiefly formed of 

 Silurian rocks, but much less altered, and rarely 

 possessing a gneissic character. These plunge beneath 

 the Old Eed Sandstone, and rise in the Grampian 

 mountains on the north changed into quartz-rock, mica- 

 schist, and gneiss. The unaltered Carboniferous and Old 

 Eed Sandstone rocks thus lie, as a whole, in a hollow, 

 between the Grampian and the Lammermuir ranges, the 

 coal-bearing strata chiefly consisting of alternations of 

 shale, sandstone, limestone, and coal, mingled with 

 volcanic products of the period. 



I have already explained, in Chapters VIII. and IX. 

 how these Old Red and Carboniferous rocks were formed, 

 showing that the latter consist of strata partly of fresh- 

 water and partly of marine origin, for not only are the 

 limestones formed of corals, encrinites, and shells, but 

 many of the shales also yield similar fossils, while some 

 strata are charged with fresh -water shells. Beds of 

 coal are numerous, and under each bed of coal there is 

 a peculiar stratum, which often, but not always, is of the 

 nature of fire-clay, and is sometimes called c underclay,' 

 this in England being a miner's term, on account of its 

 position beneath each bed of coal. As already explained, 

 the ' imderclays ' were the soils on which land plants 



