46 



escape of the Carbonic Acid, deposited the ores of Iron in the same 

 way as Calcareous Sinter, when, by the contact or under the 

 influence of Oxygen, it may become Peroxidized. Indeed, the 

 more we examine these veins in situ, and under all phases of 

 their conditions, the more am I inclined to believe them to have 

 had their origin, so far as filling-in is concerned, during the 

 period of the destruction of the Palseozoic Rocks and the depo- 

 sition of the New Red Sandstone, and again at its subsequent 

 re-elevation and re-denudation in later times. To account for 

 these views in still more concise reasoning, I may state that the 

 Brown Iron Ore found in the veins or Faults at Frampton Cot- 

 terell, and the Tortworth area, have very probably been derived in 

 great measure from the Iron which must have been present in 

 the variegated Sandstones and Marls of the New Red Sandstone 

 series, which formerly covered the Palseozoic series of the Basin,* 

 but which have been entirely removed by denudation from a 

 considerable area in the centre of the Coalfield, and also exten- 

 sively on its eastern and western borders. In the New Red 

 Sandstone the Iron occurs partly in the state of a Silicate of 

 the Protoxide, but chiefly as a Hydrated Peroxide ; of these 

 compounds the Silicates would be decomposed by water contain- 

 ing Carbonic Acid in solution, whilst the latter (the Hydrated 

 Peroxide) could not be acted upon until reduced to the condition 

 of Protoxide, a change which might, however, be readily effected 

 in various ways; such change, for example, may be effected by 

 the reducing agency of organic matter. Once brought into the 

 condition of Protoxide, it would then be readily acted upon by 

 meteoric or atmospheric waters, charged, as they always are, to 

 a greater or less extent with Carbonic Acid, thus giving rise to 

 the formation of Carbonate of Protoxide of Iron, a compound 

 easily soluble in water containing Carbonic Acid in solution, and, 

 therefore, capable of being readily introduced into any fissures 

 to which the waters might gain access. This Carbonate of Iron 

 being exceedingly unstable, is decomposed with great facility, 

 merely by exposure to atmospheric influences, its Carbonic Acid 

 being evolved whilst Oxygen is absorbed from the air, thus 

 * See Analysis, page 40. 



