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PART 2 -SILURIAN AND DEVONIAN. 



BY W. W. STODDABT, F.C.S , F.G.S. 



HAYIN'G described the igneous rocks of the Bristol district, we 

 now commence our study of the sedimentary deposits that 

 afterwards were formed by aqueous and atmospheric agencies, and 

 which, having gradually accumulated, formed the bottom of the 

 ocean. 



It was through these ancient sea beds that the molten masses 

 were protruded from the interior of the earth with powerful and 

 irresistible force. The British Isles ewe their present existence 

 to the submarine eruption of fluid lava at an immensely remote 

 period. On looking at a geological map their ancient monuments 

 may beseen studding the western parts of England and Scotland. 

 As time elapsed, the wind and tide wore away these apparently 

 hard rocks, and deposited the muddy and sandy debris which, 

 after consolidation, formed what we now see as the bottom rocks 



