LOWER LUDLOW ROCK. 



205 



frequent in other parts of the Upper Silurian Rocks, particularly in the Wenlock shale; 

 and it will afterwards appear, that from their saponaceous qualities the surfaces of 

 these beds have frequently aided the slipping of superincumbent masses of rock. (See 

 Chapter 20.) The central and lower strata afford no good stone, and are often dis- 

 posed in large sub-concretionary masses which frequently break into shivery fragments. 

 The same strata often contain smaller concretions of black argillaceous limestone, 

 varying in size from a few inches to three feet in diameter. These calcareous nodules 

 are strikingly analogous to the cement stones or concretions of the lias, and other cal- 

 careo- argillaceous formations, and are frequently formed around an orthoceras, or some 

 other organic body. Vertical or highly inclined joints occur throughout, the direction 

 and inclination of which, like those alluded to in the upper Ludlow, vary with the 

 changes in the strike of the strata. Nearly every quarry affords examples of these joints 

 or backs. (See Chapter 20.) 



The steep escarpments of any of the hills west of Ludlow expose the outcrop of the 

 strata composing this subdivision. They dip under the Aymestry limestone and upper 

 Ludlow Rock, and the same relations can be equally well studied in numerous localities 

 at the back of Mocktree Forest, Shelderton Hill, descending to Clungunford 1 , and in 

 Leintwardine Hill upon the north side of the new road between the limekilns and the 

 village below. In the inner or elevated portion of the Ludlow promontory, where the 

 strata are much dislocated, (see subsequent chapter,) the detailed relations of the beds 

 are well revealed, as in the deep comb called Mary Knoll Dingle. I may also particu- 

 larly cite a section offered on the sides of a deeply worn lane which ascends from 

 Elton to the high grounds of Evenhay, a prolongation of the ridge of Gatley Coppice. 

 Here we see the Aymestry Limestone in the cap of the hill dipping south-south-east 15°, 

 and underlaid by seams of Walker's Earth, and pendle or naglike beds, with Orthocerata 

 both large and small : argillaceous beds succeed, containing, here and there, concre- 

 tions frequently of an oblate spheroidal form, of black or dark grey, compact, argilla- 

 ceous limestone, which have been formed around organic remains (Orthoceratites, 

 Trilobites 2 , &c.) . These are underlaid by clay and friable stone bands, with other fossils, 

 including the chain coral, Calamopora, and beneath are lower hillocks, which are oc- 

 cupied by the underlying limestone of Wenlock. The Garden House quarries near 

 Aymestry, expose excellent sections of apart of this subgroup, and the fine vertical cliffs 

 on the left bank of the Lugg, between Aymestry and Deerfold Chase, are also com- 

 posed of it. 



1 The geologist who may examine this tract cannot observe a more instructive section of the middle and lower 

 members of the Ludlow formation than that which is laid open on the sides of the rugged road which descends 

 Shelderton Hill. The hospitality of my kind friend, the Rev. J. Rocke, whose house, of Clungunford, is near 

 the base of the hill, enabled me thoroughly to examine this section. 



2 In company with the Rev. T. T. Lewis, I counted forty fragments of the Asaphus caudatus in a single 

 nodule. 



2 c 



