136 



GENERAL STRUCTURE OF THE COAL-FIELD. 



in some parts so perforated by upcasts of the underlying Old Red Sandstone or intru- 

 sions of trap, that no geologist would think of there resuming mining operations. 

 Again, the fine section exhibited on the right bank of the Severn, of the carboniferous 

 sandstones which compose the greater part of the Forest of Wyre, as well as the deep 

 natural openings in the forest, prove that the district cannot contain any valuable 

 seams of coal. 



With respect to the connexion of the carboniferous strata with the overlying and 

 subjacent red sandstone, it is necessary to say a few words to prevent a casual visitor 

 from mistaking the true nature of these different deposits. In those situations where 

 the Old Red Sandstone, with its associated cornstones, rises up in knolls through the 

 coal measures, the appearances are so fallacious that they might induce unpractised ob- 

 servers to suppose, that these older rocks were truly included in the carboniferous de- 

 posits, particularly as calcareous concretions very similar to that of the Old Red occur 

 at intervals, both in the overlying lower New Red, and in the upper coal measures. 

 The true cornstones of the Old Red, as will be explained in a subsequent chapter, are 

 usually to be distinguished from those of the other deposits, by the associated strata of 

 red rock, which are generally harder, thinner bedded, and in other respects dissimilar 

 to those of the Newer Red Sandstone ; whilst, wherever the Old Red Sandstone un- 

 derlies or rises from beneath, as along the western boundary of the coal-field, there can 

 be no mistake. There are, however, anomalous lithological appearances in some of 

 the rocks which flank these coal-fields on the west of Kinlet ; for example, at Prescot 

 Wood and Oreton, where the strata of Old Red Sandstone, though clearly passing 

 beneath the carboniferous limestone, put on so completely the lithological characters 

 of coal sandstones, that I am persuaded no one could have disentangled the subject of 

 its apparent intricacy, who had not worked consistently and for a long time over a large 

 area of the surrounding formations 1 . Again, the deep red ferruginous clods of some 

 parts of these coal measures (the " horse-flesh" beds of the Glee Hills) are not very 

 dissimilar in mineral structure from the red argillaceous marls of the Old Red Sand- 

 stone. 



Like the coal-fields of the plain of Shrewsbury, and those patches south of Broseley, 

 this tract contains subordinate strata of calcareous matter, and passes up as already 

 stated in certain parts into the Lower New Red Sandstone, p. 60 ; but as yet I have 

 not discovered any animal remains to enable me to speculate on the probable condition 

 of the waters under which these accumulations were formed. Vegetable impressions 

 are numerous, and are found not only in the shale or roof of the coal, but in the district 

 east of Cleobury Mortimer, they are of frequent occurrence in the sandstones. 



1 See an account of these yellow sandstones of the Old Red Sandstone in the fourteenth chapter. Similar 

 varieties of the Old Red will also be described in the Chapter upon Pembrokeshire. 



