200 Mr. AiKiN on the Wrek'itiy and on the 



tion. It consists of a line of hills, between five hundred and six 

 hundred feet above the level of the Severn ; and about two hundred 

 feet above the second ridge, hereafter to be described. These hills 

 consist of beds of limestone and sandstone rising to the N.W. ; hence 

 their south-eastern sides present an uniform slope, while their north- 

 western are nearly precipitous. They are separated from each other 

 by short strait vallies, which run nearly in the direction of their dip 

 and rise -, and from their nearly equal heights, their correspondence 

 of stratification, and the strait line along which they are distributed, 

 there can be but little doubt that the vallies, by which they are se- 

 parated from each other, are of later formation than the hills, which 

 last at some former period constituted an uninten'upted range. This 

 limestone is characterized by the madrepores which it contains, par- 

 ticularly the catenariaj or chain coral, by the pentacrinite, by small 

 ammonites, by a few bivalve shells, and especially by the natural 

 joints of the strata being often lined by flesh-coloured tabular heavy- 

 spar. Detached lumps of galena are often found on the surface, 

 and a few small veins of the same mineral have been traced in various 

 parts, but chiefly near the southern extremity of the range ; cavities 

 lined with and occasionally full of petroleum occur at the northern 

 extremity, where it comes in contact with the coal-formation. The 

 names of the hills constituting this tract of limestone are, Mochtre 

 Forest on the borders of Herefordshire, Norton Walls, Feifton 

 Forest, Munslow Hill, Mogg Forest, Benthal Edge, and Lincoln Hill. 

 The elevation of the strata, from the Herefordshire border to the 

 northern extemity of Mogg Forest, does not exceed an angle of 9° ; 

 but when, after having crossed the upland valley in which Mar 

 brook takes its rise, we arrive at Benthal Edge, it appears that this 

 latter ridge, though evidently a mere continuation of that already 



