DISLOCATIONS. 



Ill 



been ascertained. Again, in the centre of the field, the masses have been so elevated, 

 that the very lowest beds of the coal measures are brought to the surface, all the supe- 

 rior strata having been destroyed and denuded. 



The most powerful dislocation within the field is called the Lightmoor Fault, and 

 is an upcast of more than two hundred yards at the point of its greatest intensity ; but 

 it appears that the strata are unequally dislocated at different spots, even along the 

 same line of fault, and in some instances the change of level would seem to have been 

 the result of a series of small dislocations. 



General reflections on these phenomena will be offered, as soon as my readers have 

 become acquainted with the more ancient deposits of this neighbourhood, and the 

 various volcanic products with which they are associated. I now restrict myself to the 

 observation, that the north-easterly and south-westerly direction of these faults and 

 basaltic outbursts is parallel, to the fissures along which the Wrekin, Caradoc, and 

 other trap rocks of more ancient date have been erupted, and also to the lines along 

 which the Silurian and older sedimentary formations have been elevated. 



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