47 



converting the Carbonate into a Peroxide of Iron; which, being 

 insoluble, is deposited in the state of Hydrate as a reddish- 

 brown precipitate, the reactions being indeed indentical with 

 those which are occurring daily in every Chalybeate spring, or 

 where Tufas and Sinters are similarly deposited. The Hydrous 

 Peroxide of Iron thus formed might either be precipitated on 

 the walls of the Fissure or Lode in successive deposits and 

 layers, as may be well seen in certain regiilarly banded specimens 

 from the Prampton Mines, and the openings near Mudgedown 

 Farm to the north: or it may be more slowly deposited in 

 stalactitic forms, of which the Frampton Cotterell workings 

 present beautiful examples, consisting in many cases of fine 

 pendant masses of compact brown ore, surrounded by coatings 

 of the crystalline or fibrous variety termed Gothite, and 

 resembling in their general characters the well-known specimens 

 from the Restormel Iron Lode, near Lostwithiel, in Cornwall. 

 Now when we reflect upon the vast m.ass of these Iron-charged 

 Red Sandstones and Marls* that once rested upon the Coal 

 Measure Rocks of this area, and admit the theory that long- 

 continued percolation and infiltration, both during the period of 

 deposition, and after by the slow agency of water through long 

 periods of time into fissures and joints, it would, I believe, fully 

 account for the origin of the Hydrated Oxides now stored in the 

 fissures and faulted recesses of the Carboniferous Limestone, 

 Millstone Grit, and Penuant Rocks below. 



We must not fail also to recognize and consider the great 

 influence that the subsequent removal of these Red rocks must 

 have had upon the exposed land surfaces, probably after the 

 Oolitic period, when the waters were again charged with the 

 Silicates and Carbonates of Iron. Remnants of these Lower 

 Red Sandstones (if not Permian) are now familiar to us in the 

 patches of Dolomitic Conglomerate which fiinge the edges of 

 the Basin, and in places, the remaining masses of the New Red 

 Sandstone, which stni cover up large subterranean tracts of 

 Palaeozoic rocks. 



* See Analysis, page 40. 



