24 



vention of any large body of limestone a peculiarity worthy of notice 

 in all the coal fields of central Scotland. The entire phenomena of 

 this field are highly instructive. 



20. The varied phenomena of these interesting fields maybe studied 

 to advantage in many natural sections. The Lesmahagow field 

 through its whole area, and along its borders, is completely opened 

 up by glens and deep water channels, which exhibit the succes- 

 sion of the strata and many remarkable faults. The banks of the 

 Nethan, Calder, and other streams which pursue rapid courses from 

 the high uplands into the profound synclinal trough traversed by the 

 Clyde downwards from the Falls, and the banks of the Clyde itself, 

 present many instructive sections and most favourable localities for 

 collecting fossils. The fresh-water series, across the central area, is less 

 completely exposed, and is best known from interior workings and 

 boring journals. The marine series is laid more fully open. It 

 reaches out on either side to the base of the hill ranges bounding the 

 area; and these, composed of igneous rocks, erupted through the 

 coal formation, or along its outer margin, bear up the various "mea- 

 sures" on their flanks, and bring them to day in deep glens and the 

 banks of mountain burns. In the Lennox range we have, already 

 mentioned the Auchinreach and Spittal glens, opening respectively 

 into the Leven and Strathblane valleys ; the Ballagan, Finn, and 

 Clachan glens, descending into the vale of Campsie, near Lennox- 

 town ; these expose the subjacent Old Red, the intermediate Ballagan 

 beds, and the lower members of the coal formation. Farther east 

 there is an interesting section of beds somewhat higher in the 

 series one of the most instructive in the w r hole Clydesdale basin, and 

 to which the attention of the student cannot be too emphatically 

 directed. We refer to the succession of beds laid open in the middle 

 portion of Corrie glen, one mile west of Kilsyth, as shown in the 

 following cut. 



The strata here exposed lie between two streams descending from 

 the high trap ranges to the N.W., and uniting farther down before 

 entering the valley of the Kelvin. Of these the West Burn, the 

 upper portion of which is represented in the sketch of Art. 12, cuts 

 most deeply into the soft shales and sandstones which are finely 

 shown in a nearly vertical section. Workings on the economic 

 strata farther favour the researches of the student. 



The strata belong to the lower marine series. The yellow sand- 

 stone (ri) at the base is higher than that of the Campsie valley, and 

 the two limestones (g) and (/), respectively 3 and 5 feet thick, are 

 also superior to the Campsie main limestone. The shale beds (/*) 



