Page:Transactions of the Geological Society, 1st series, vol. 1.djvu/212

 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 separated from each other, are of later formation than the hills, which last at some former period constituted an uninterrupted range. This limestone is characterized by the madrepores which it contains, particularly the catenaria, 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 extremity 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