526 



SECTIONS OF GRAVEL, ETC., NEAR SHREWSBURY. 



Local. 



Again, around the field of Coal Brook Dale, there is distinct evidence of much local 

 detritus, derived from the breaking up of the red sandstone and the protrusion of coal 

 measures, Silurian rocks, trap, &c. ; and the local detritus is overlaid by the drift con- 

 taining northern bowlders 1 . Excellent examples of this superposition may be seen near 

 Buildwas and the Iron Bridge, where mounds of regenerated red sandstone, the residue 

 of the rocks shattered during the rise of the coal-fields, are wholly exempted from 

 foreign detritus, though the latter, containing many varieties of northern granite, is 

 found on the surface, both surrounding and partially covering the coal-field. 



Similar phenomena, though of rather a more complicated character, are observable 

 on the banks of the Severn, near Shrewsbury, as expressed in the accompanying wood- 

 cut. 



Section on the right bank of the Severn at Preston Hall, 4 miles south-west of Shrewsbury. 



"a. Soil of heavy clay and loam containing a few bowlders of 107. 

 northern granite, fragments of Silurian and Cambrian 

 Northern J rocks, and small pieces of the carboniferous strata,inos- 

 Drift? \ culatingwith sandy loam and sand. 



b. Reddish foxy sand, in fine layei-s alternating with laminae 

 of brown sandy clay, a few pebbles, &c. 



"c. Irregular alternations of coarse gravel and finely laminated 

 sand. The former contains shingley, flattish, water- 

 worn fragments of all the surrounding rocks, the sand 

 j_ being of light red colours. No granite in this mass. 



d. Regenerated red sandstone. 



e. New Red Sandstone. 



Sections varying in detail, but presenting the same general arrangement, are visible 

 at Shelton Rough and other places on the banks of the Severn, near Shrewsbury. 

 At the base they consist of soft deep red sandstone without any foreign pebbles, 

 the mere disintegration of the red rock, which is seen beneath in situ. This bed is 

 covered by mixed detritus of foxy-coloured gravel, made up of the rocks above men- 

 tioned, with chert and grit of the coal measures, and being of a dingy grey tint, it is 

 strongly contrasted to the red colour of the underlying mass. A speculator might 

 endeavour to prove, that these deposits, being of different colours and composition, are 

 referrible to separate epochs of drift. He might argue (and with plausibility), that after 

 the great banks or shoals of red sand, which generally occupy the lowest position, had 

 been elevated to a certain extent, matter of different composition was drifted on them, 

 the sand banks themselves being modelled and rounded off by the action of the re- 

 treating sea. But I have seen too many cases in which that order is reversed, and in 

 which red sand re-occurs, overlying grey detritus of coal grits and older adjacent rocks, 

 to admit such a speculation. All we can safely affirm, is, that the different sections 

 vary very much in their composition ; though they all have the aspect of having been 



practicable to refer the great heaps of these pebbles in the eastern slopes of the Clent or Higher Lickey to 

 the little ridge of Lower Lickey. The various sites of the same quartz rock, near the Wrekin, Caradoc, &c, 

 were probably the sources of these great masses. 



> Mr. Prestwich has also noticed this arrangement, Geological Proceedings, vol. ii. p. 404. 



