176 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Jail. 7, 



town, have been rendered tolerably clear by the researches of the 

 Ludlow geologists, and by the discoveries made during the progress 

 of the drainage-works. Upon these " passage-beds" and the under- 

 tying Downton Sandstone the town is mainly situated. The over- 

 lying Old Red Sandstone is well seen in the line of the section in 

 the railway -cutting. The Downton Sandstone, about 80 feet thick 

 at Ludlow, has been generally included in the Silurian rocks : it is 

 a yellow micaceous sandstone, very similar in composition to the 

 Caradoc, from the denudation of which, it has, most probably, been 

 derived. But few organic remains occur in it at Ludlow, the prin- 

 cipal being the Fishes — Pteraspis and Cephalaspis, — with the Crus- 

 taceans — Eurypterus, Pterygotus, and the small Beyrichia. Above 

 this rock is a very hard, greenish, micaceous sandstone containing 

 lime, much resembling an Old Bed Cornstone in mineral composi- 

 tion. The Bull Bing is situated upon this rock, and no doubt owes 

 its present relative altitude to the hardness of this sandstone and 

 its capability of resisting denudation. Above it are several thin 

 beds of sandstone, in which nothing organic has been found. Next 

 occurs a greenish micaceous sandstone, containing Cephalaspis, lan- 

 guid, &c. We then come to the " Olive Shales," which are thin 

 argillaceous beds, easily broken, and containing layers and thick 

 masses of fossils. Several species of Pterygotus and Eurypterus, and 

 spines of Onchus have been found. A thin sandstone-band forms a 

 capping to these olive shales, and underlies a bed of Old Bed marl 

 about 80 feet in thickness. On the top of this marl, N.E. of Ludlow, 

 is situated the high-level gravel, in a bed about 30 feet in thickness. 

 The rain-water, falling on this gravel-bed, percolates through it, and 

 issues forth as a spring. Yery nearly the whole of the sand and 

 gravel here deposited is composed of Old Bed Sandstone debris. The 

 inclination of the sand-belts and their thinning-out towards the east, 

 in this drift, indicate the direction of the current which brought this 

 gravel to the lake in which it was deposited to have been from the 

 westward. It is probable, therefore, that, prior to the deposition 

 of this gravel, the Silurian rocks, which now form the entire area of 

 the district west of Ludlow, were masked to some extent by Old Bed 

 Sandstone, since removed by denudation. 



By subsequent denudation, and an alteration of currents, this 

 " high-level lake " became drained, and a lower lake formed about 

 100 feet below it. Currents from the north deposited sand, gravel, 

 and other drift in this lower basin, which now forms the site of 

 Corve Street. This gravel-bed is composed chiefly of Cambrian and 

 Silurian debris, water- worn fragments of the well-known Cambrian 

 rocks of Church Stretton being abundant. A very small part of the 

 present site of Ludlow would, during the deposition of this " low- 

 level gravel," appear above water. The south edge of the lake ap- 

 pears to be opposite the Feathers Hotel, in Corve Street. A little 

 lower down that street, opposite the Compasses Inn, large boulders 

 of Old Bed Sandstone Avere discovered, resting amongst sand, 

 gravel, and line clay. These boulders must have been carried to 

 their present position by floating ice, which became stranded in 



