466 



LOWER NEW RED SANDSTONE. 



space from beneath the 10 yard coal, occupying a nook, in which they fold over and 

 dip beneath the Lower New Red Sandstone. To the south, east and west, however, 

 the whole of the carboniferous masses (i. e. both the thick and thin coal) are brought 

 up against the Lower New Red Sandstone by enormous faults. 



It was till very recently a prevalent belief, that this red sandstone entirely cut off 

 the coal, and that the latter would never be found under the former ; but this notion, 

 (like the vulgar error concerning the magnesian limestone of the North of England, 

 which has long been dissipated,) is now fast vanishing, and will, I trust, be entirely 

 removed from the minds of the practical men who may favour me with a perusal of 

 these pages 1 . 



After this preamble we may proceed to the consideration of the Lower New Red 

 Sandstone and Coal Measures, including certain tufaceous conglomerates or volcanic 

 grits which alternate with both these deposits, and in the next chapter complete the 

 geological history of the tract by describing the Silurian rocks on which the coal-field 

 rests, the trap rocks by which it is penetrated and altered, and the dislocations by which 

 it is affected, concluding with some general observations on the extension of coal 

 beneath the New Red Sandstone. 



Lower New Red Sandstone. 



Exclusively of loose detritus, the Lower New Red Sandstone, as already shown, is the youngest 

 formation in the vicinity of the coal-field, around which it forms a continuous and widely spread 

 mass. (See Map,) The deposit has been previously stated to be of great thickness in this district, 

 as proved both by natural sections around the edges of the coal-field, and by the sinkings of the 

 Earl of Dartmouth. (See p. 58.) 



In mineral characters the formation varies considerably in different localities. We have already 

 described, p. 56, a yellowish soft sandstone at the southern end of the field (Hodge Hill, &c.) 

 which very much resembles the " Rohte todte liegende" of the county of Durham. This rock re- 

 appears in open sections on the western flank of the field near Himley, Holbech, Swindon, &c. 

 At Holbech it is overlaid by deep red, loamy, finely laminated sandstone, with layers of greenish 

 flags dipping 35° to the north-east. At Swindon the laminae of the soft yellowish sandstone are 

 occasionally marked by very thin carbonaceous partings. The great mass, however, of the Lower 

 New Red Sandstone surrounding the field, differs from the rock of the same age in the north of 

 England, being a deep, dull red, finely laminated sandstone, calcareous in parts, with numerous 

 whitish grains of decomposed felspar and concretions of impure limestone. 



Towards the southern and south-eastern extremities of the field, the 10 yard coal, as will be 

 shown, passes under the red sandstone. In truth, much of the tract in that neighbourhood (Corn- 

 greaves, &c.) which is now part of the coal-field, was, when Mr. Keir wrote, deemed to be far 



1 See my previous communications on this subject to the Geological Society of London, which memoirs 

 constitute the rough outline of this volume. 



