524 



OLD RED SANDSTONE. 



[Ch. XXVI. 



thickness, sometimes between 8000 and 10,000 feet. In these re- 

 gions it has been subdivided into 



1st. Conglomerate. 



2dly. Brownstone series — chiefly reddish-green and brown sand- 

 stones, with large JEurypterus. 



3dly. Marl and Cornstone — red and green argillaceous spotted 

 marls, with irregular courses of impure concretionary limestone, pro- 

 vihcially called Cornstone, and some beds of white sandstone. In 

 the cornstones, and in those flagstones and marls through which cal- 

 careous matter is most diffused, some spines of fish of the family 

 Acanthodidcs, and remains of Cephalaspis and Pteraspis occur. 



4thly. Ledbury Shales — thin olive shales of Ledbury and Ludlow, 

 and sandstones intercalated in thick beds of red marl. Fish of the 

 genera Cephalaspis, Auchenaspis, &c, specifically distinct from those 

 of the underlying Silurian. 



Old Red Sandstone of Scotland and Ireland. — South of the Gram- 

 pians, in Forfarshire, Kincardineshire, and Fife, the Old Eed Sand- 

 stone may be divided into three groups : 



A. Yellow sandstone. 



B. Eed shale, sandstone with cornstone, and at the base a con 



glomerate (Nos. 1, 2, and 3, Section, p. 48). 



C. Roofing and paving stone, highly micaceous, and containing a 



slight admixture of carbonate of lime (No. 4, p. 48). 



The united thickness of A, B, and C, in Fife and Forfarshire, must 

 amount to 3000 or 4000 feet ; and perhaps in some places, where the 

 conglomerates of B are largely developed, to much more than 4000. 



A. — The upper member, or yellow sandstone, is seen at Dura Den, 

 near Cupar, in Fife, immediately underlying the coal. It consists of 

 a yellow sandstone in which fish of the genera Pterichthys (for genus 

 see fig. 600), Pamphractus, Bothriolepis, Glyptopomus, Holoptychius, 

 and others abound. 



In Ireland the upper beds of the Old Red, or yellow sandstone oi 

 Kilkenny, contain fish of the genera Coccosteus and Dendrodus, 

 characteristic forms of this period, together with plants specifically 

 distinct from any known in the coal-measures, but referable to the 

 genera found in them ; as, for example, Lepidodendron, Cyclopteris 



Fig. 585. 



Fig. 586. 



Stem of Zepidodmdroii, so compressed as 

 to destroy the quincunx arrangement of 

 the scars. Upper Devonian, Kilkenny. 



Cyclopteris Hibemiea, Forbes. 

 Upper Devonian, Kilkenny. 



