214 Murchisoris Silurian System. 



was surprised that no change of metal was met with, though the 

 youngest geologist would have told him that no change could occur where 

 strata, of infinitely older date than any connected with the carboniferous sys- 

 tem, were in a vertical position. To point out more clearly the folly of 

 this and similar attempts, I annex a small general section of this little 

 carboniferous patch, showing its relations to the ancient and barren 

 rocks on which it rests. The coal strata here dip north-north-west at 

 a slight angle, and, as appears in the diagram, they are subject to many 

 faults, the chief of which run from north-north-east to south-south-west. 

 From Uffington we must travel some miles to the east or south before 

 we reach any other patch of coal, the intervening tracts being occupi- 

 ed either by old Cambrian rocks rising to the surface, or covered by the 

 lower members of the new red sandstone and great accumulations of 

 gravel. It is probable, however, that on many points the coal has 

 never been deposited, since we occasionally see the lower new red 

 sandstone reposing directly upon the older rocks. 



" One small deposit is found atDryton, on the south-western slope of 

 the Wrekin ; and in the more superficial parts of it, near Longwood, 

 coal was long ago extracted ; but it has more recently been followed to 

 a greater depth at the former place, where two seams are now in work ; 

 the shaft is thirty yards deep, eighteen of which are sunk through over- 

 lying detritus of red sand and pebbles, &c. The uppermost of the beds 

 of coal is two feet, the lowest three quarters of a yard thick, separated 

 by clods and sandstone, and there are no traces of the limestone or of 

 the third bed of coal. The dip is three inches in a yard to the south- 

 east. 



" On the south bank of the Severn, the bay formed in the older rocks 

 between the ridge of the Caradoc on the east, and Lyth hill on the 

 west, abounds with carboniferous patches, which vary in the amount 

 of their productiveness, precisely in the ratio of the depth at which the 

 underlying rock is found. For example, at Cound, Pitchford, and other 

 places, where these old rocks (upper Cambrian) occasionally protrude 

 to the surface, the adjacent carboniferous strata are mere shreds, some- 

 times covered by the newer red sandstone, but towards the centre 

 of the trough the coal strata thicken, and at Le Botwood, near 

 Longnor, we again meet with nearly the same development as in the 

 Pontesbury field. These beds dip east-north-east 10°, or away from the 

 contiguous promontories of older rocks. The shaft at Le Botwood is 

 sixty-three yards deep, passing through shales, limestone, and coal. 

 The shale or roof of the coal is particularly rich in the plants, and those 

 which I collected were identified by Professor Lindley, and form part 

 of the list previously given. 



