272 



GEOLOGY OF THE BRISTOL COAL-FIELD. 



Fig. 12. Hungroad Section, shewmg irregular hedding, 

 — r n~ 



The Devonian fossil fauna indicates a marshy country, accessi- 

 ble to the encroachment of high tides. The comparative absence 

 of Conchifera and other marine forms supports the opinion of Sir 

 Charles Lyell and Professor Huxley, that the fish of the old red 

 f period inhabited a swampy region, like the banks of the Nile, 

 Gambia, and Senegal. In those places the Polyp terus abounds, 

 which has a great resemblance to the Devonian Holoptychius, 

 Osteolepis, Dipterus, Glyptoltmus, &c. It is singular, too, 

 that all these belong to the fringe finned fishes (Crossopterygidae). 

 In the village of Portishead the Devonian beds have been 

 broken and greatly displaced. The woodcut (fig. 13) shews this, 

 and also a fault that has divided both the Devonian and Car- 

 boniferous rocks. 



Fig. 13. Section at Portishead. 

 b 



a Devonian.— ^^ Carboniferous.— c Trias.— c? Alluvium. 



