great Coal-Jield of Shropshhe. 201 



described, rises at an angle of Vl\ Soon after, the strata change their 

 direction from N.N.E. to east by north, and at the same time acquire 

 an elevation of '2>Q°. Benthal Edge is separated from Lincoln Hill 

 merely by the narrow valley of the Severn, at that place not tvv'o 

 hundred yards wide ; and the strata of this latter hill have the same 

 direction as Benthal Edge, but their horizontal angle has increased to 

 45", and the height of the hill above the level of the Severn is con- 

 siderably inferior to that of Benthal Edge. Beyond Lincoln hill 

 the strata, as far as they have been explored, preserve the same angle 

 and direction ; but their height is not superior to that of the coal- 

 field which they traverse, hence the circumstances of their termination 

 in the neighbourhood of the red sandstone are unknown. 



In a geological point of view, the limestone strata above described 

 are remarkably interesting. We see them stretching for several 

 miles, nearly in a strait line, N.E. and S.W. with an elevation not 

 exceeding 9° ; and this part may be considered as exhibiting the 

 limestone, with regard to these circumstances, in its original situa- 

 tion. The interval now occupied by the valley of Mar brook points 

 out the direction of a fracture caused by the motion of the whole 

 body of limestone between this brook and the Severn, which has 

 elevated its north-western and proportionally depressed its south- 

 eastern extremity. The narrow valley of the Severn itself points 

 out another nearly parallel fracture, caused by an analogous and pro- 

 bably contemporaneous motion of the strata of Lincoln Hill, by which 

 it is obvious that the present valley of the Severn was formed^ 

 With the above unequivocal fact is connected an important object of 

 enquiry, namely, the mode by which the elevation and depression 

 of these beds was effected. 



With regard to this question, it may be observed that strata are 

 capable of vertical motion by a force acting either from below up- 



2 c 



