Geology of Herefordshire, S^c. 43 



dejection of sandstone and brecchia rocks has formed the terrtu 

 firma of the vales. The N.W. acclivity and S.W. decline ; the 

 exact correspondence of strata in opposite hills at parallel 

 heights ; the springs constantly found towards the S. W. sides ; 

 the tributary brooks in the gorges of the hills, washing, in their 

 course, sand into the river ; the soil being every where alluvial ; 

 the line of bearing from Ross to Chepstow ; the rocks of pud- 

 ding stone lying in the bed of the Wye ; convince me that the 

 face of the country is owing to these causes, and that the Wye 

 has been formed with a regular channel by a general excavation 

 of the hills in its course. Extensive paludal traces are yet 

 abounding. As to the limestones, I have nothing to offer con- 

 cerning their origin, I cannot deem them to be synchronous with 

 sandstone, for we do not find them diffused over the alluvial 

 soil, and therefore cannot have been exposed to that operation, 

 to which we are indebted for the latter. 



This part of the empire is the great district of limestone 

 ranges. A great part of the solid globe is formed by the union 

 of carbonic acid with lime in both a fluid and a solid state : in 

 fact, in all shapes. It is possible that the base is in a most pro- 

 lific degree the result of an animal origin, and the gaseous ad- 

 duct is equally prolific, in combination with the atmosphere. 

 On exposure to a great heat, the black marble of Milford, in 

 Wales, gives a strong fetid smell, from which we may perhaps 

 infer, that the colouring principle is a pigment of animal matter. 

 The limestones which I have mentioned are all congeries of 

 shells : from the secretion of an insignificant shellfish arises 

 a large proportion of the solid structure of the earth. A gentle- 

 man in India, to prove the fecundity of the animals of shells, 

 put a few snails in a pail containing water and other things 

 necessary to their existence, and he was surprised to fitjd that 

 they very soon filled it. 



We now come to coal. Thin outcrops of this are found every 

 where over the limestone ; towards the forest of Dean, it abound* 

 in Mimdic, burns very slowly, and leaves much yellow sandy 

 and white flaky residua. Its gaseous contents are less than 

 those of the Northern coals. It lias been a speculation, fre- 



