202 Mr, AiKiN on the Wrek'in and on the 



wards, or from above downwards ; in the former case, the force 

 must have been applied to the elevated portion, in the latter, to that 

 which is depressed. It does not appear how a great extent of strata 

 can be first raised and afterwards supported in its new position other- 

 wise than by a mass of fluid matter, capable of subsequent consoli- 

 dation, bursting up from below with a great force ; nor on the other 

 hand is it easily conceivable how an extensive depression can take 

 place except by some great cavity under the depressed part giving 

 way. Now, in the present instance, if we examine the elevated 

 extremity of Benthal Edge, we shall find that between the abrupt 

 termination of this, and the low range of limestone called Wenlock 

 Edge, (hereafter to be described) which lies about a mile to the west, 

 the whole intervening space is occupied by shattered fragments of 

 limestone strata and great irregular deposits of die-earth, but without 

 the smallest appearance of basalt, amygdaloid, or those other un- 

 stratified rocks which by many geologists are considered as the great 

 instruments by which the heaving up of strata is effected. The non- 

 existence, at least the non-appearance, of these in the present case, 

 countenances the opposite hypothesis of depression ; and this 

 appears still more probable from an examination of the coal strata 

 superincumbent on the eastern end of the Umestone in the parish of 

 Brosely, which are full of fractures, thus indicating very considerable 

 disturbance in that part. 



The western range of Limestone runs precisely parallel to that 

 already described as far as the Severn j its average height rarely ex- 

 ceeds three hundred feet above the level of this river. It forms an 

 unbroken range with a nearly even top, on which account it is known 

 by the name of Wenlock Edge. It is very full of tubulites and other 

 coralline remains, but I have ne\er seen in it any of the heavy-spar 

 which ^characterizes the eastern range. In its line of direction and' 



