296 Analysis of the 



strata that now occupy the north of England, thus, with 

 part of the Old Eed Sandstone, covering great part of 

 the Silurian strata of the south of Scotland. This un- 

 conformable covering has, however, in the course of re- 

 peated denudations, been removed from the greater 

 part of that high area, and now the Carboniferous strata 

 are only found in force in the great central valley 

 through which flow the rivers Forth and Clyde. 



This will be easily understood by referring to the 

 section, fig. 55, across the central valley of Scotland, 

 from the Grampian mountains to the Lammermuir 

 hills, in which the following relations of the various 

 formations are shown. 



The gneissic rocks of the Grampian mountains (No. 

 1), with bands of Limestone marked + , pass under the 

 Old Red Sandstone (No. 2), and rise again, highly dis- 

 turbed, but not much metamorphosed, in the Lammer- 

 muir hills (I'). On these the lower conglomerates of 

 the Old Red Sandstone (No. 2) lie unconformably, 

 adjoining and overlying which, there is a series of beds 

 of red sandstones which generally dip SE. for a space 

 about ten miles in breadth, as seen, for example, on 

 either side of Strath Earn and the Tay above Perth. 

 These are succeeded by an upper series of Old Red 

 Sandstone rocks, which run from the neighbourhood of 

 Stirling to the estuary of the Esk, near Montrose, on the 

 east coast, and to Cupar and the mouth of the Firth of 

 Tay, at Ferryport. The lower part of this upper series 

 is often inter stratified with volcanic lavas, ashy breccias, 

 and conglomerates of a felspathic nature. These being 

 hard and dipping south-easterly from the Forth to the 

 mouth of the Tay, generally form a high escarpment, 

 the steep-scarped front of which faces to the north-west, 

 in accordance with a law that, on a great scale, rules the 



