45 



the atmosphere and water are brought into play: for in every 

 quarry where the planes of joints and smaller fissures are exposed, 

 it will be found that the faces or sides of these planes are 

 coated and filled with rich Hsematite Iron Ore. Examination 

 underground at Frampton Cotterell and other places, testifies to 

 the acciunulation of Iron in the same manner, though in this 

 latter case due to the action of large quantities of water, 

 carrying with it Iron in suspension, taken up by percolation 

 through a porous sandy matrix charged with the mineral in 

 question. 



I have remarkable and fine specimens shewing these conditions 

 from joints and fissures, taken both from underground and from 

 numerous quarries worked in the district. Again, the walls 

 of the Great Fault and main lode at Frampton Cotterell are 

 festooned with bunches of "Brush Ore," which hang from 

 sohd irregular walls of Iron, which Hne the vertical sides of the 

 great fissure, this being only a more extended condition of 

 the same phenomena under more favourable conditions for 

 accumulation. 



Fig. 8. — Section allowing Fault and Iron Lode. 



I cannot satisfy myself that these lodes are the result of causes 

 acting directly from within, or are entirely esoteric in their 

 origin, or due to subten-anean calorific agency or sublimation, 

 many of which we know to be at work in the earth's crust. We 

 have no evidence of water at high temperature having had 

 any important office in their accumulation, though it is not 

 improbable these ores may have been accumulated by means of 

 the solvent powers of water, saturated with Carbonic Acid, and 

 holding Proto-carbonate of Iron in solution, and then, by the 



