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nucleus. (Murchison.) The thickness of the formation is about 700 feet at Malvern.
Amongst the fossils are numerous Starfishes, Palasterina, Palcaster, Palæocoma, Protaster; many Crustacea, Pterygotus, Hemiaspis (4 species), Eurypterus punctatus, E. Brodiei, Ceratiocaris Ludensis, Trilobites, &c.; Graptolites; Cardiola interrupta, Murchisonia Lloydii, Orthoceras Ludense, Phragmoceras, Lituites, Lingula lata.
In ascending, the strata (according to Murchison) become somewhat more sandy, constituting thick flagstones called 'pendle' by the workmen. They have attracted much attention at a spot near Leintwardine, and have yielded many remains of Crustacea and Starfishes. These beds, says the same authority, form the support of the Aymestry limestone, from which they are usually separated by soft soapy beds, in parts an imperfect fuller's earth. It is the decomposition of this unctuous fuller's earth (provincially Walker's earth) beneath heavy masses of the limestone which rest upon it, which has occasioned numerous landslips both near Ludlow and in neighbouring parts of Herefordshire. The Lower Ludlow Shale as described by Murchison occupies the escarpments and contiguous valleys of the Ludlow rocks which range from Shropshire by Presteign to Radnor Forest, and also large undulating tracts of the western parts of Shropshire or contiguous parts of Montgomeryshire. In the Usk, Tortworth, Woolhope, and Malvern districts it is well known.
IRELETH SLATE GROUP in part. (Sedgwick.)
This group, as developed in the Lake District, is placed on the horizon of the Lower Ludlow and Wenlock Shale.
The Bannisdale Slates are described by Mr. Aveline as consisting of sandy mudstones divided by thin bands of hard
sandstone and occasional beds of grit. The sandy mudstones are much jointed and roughly cleaved, never making good slates, but often large rough slabs, quarried for paving or building stones. The total thickness of the formation is about 5,200 feet.
Fossils are scarce: they include Rhynchonella navicula and Phacops Downingiæ.
The lowest beds are seen near Kirkby Lonsdale.
AYMESTRY LIMESTONE. (Murchison.)
The Aymestry or Ludlow Limestone occurs in beds of a concretionary character, though this feature is not so conspicuous in them as in the Wenlock Limestone. It is of a bluish-grey and mottled colour, containing numerous layers of shells and corals, and associated with it are beds of shale. It occurs in strata from one to five feet in thickness, but these are very impersistent. Salter indeed regarded it as only a calcareous condition of the Lower Ludlow formation. It may be traced in Herefordshire, Shropshire, and Staffordshire, where it is often extensively worked. South-west of Aymestry it thins out, but it is represented at Usk, May Hill, Abberley, Malvern, &c. Its thickness may reach from 30 to 40 feet.
The fossils include Protaster, Palcaster, Phacops, Calymene, Acidaspis, Ceratiocaris, Pterygotus, Slimonia; also many species of Mollusca, Pentamerus Knightii, Rhynchonella, Lingula, Strophomena, Atrypa, Bellerophon, &c.
UPPER LUDLOW BEDS. (Murchison.)
These beds consist of flaggy arenaceous shale, with beds of thin shelly limestone. Some of the lower beds are termed mudstones. Their thickness near Ledbury is 140 feet.
The beds yield among Crustacea, Eurypterus, Pterygotus,
Hemiaspis, Slimonia, Phacops, Homalonotus Knightii; also Orthoceras bullatum, Pteropods, Gasteropods, Lamellibranchs, and Brachiopods.
The base of the rock is sometimes marked by calcareous shelly courses, containing Terebratula (Rhynchonella) navicula, and Leptana lævigata.
The beds are well shown at Ludlow, Ledbury, Malvern, Abberley, near Usk, &c. They are extensively quarried for building purposes.
The uppermost Ludlow rocks consist of finely laminated greenish-grey sandstones, overlaid by the Ludlow Bone-beda thin layer, of from one inch to a foot in thickness, made up of a mass of bony fragments of fish-defences, coprolites, spines of Onchus tenuistriatus, and fragments of Pteraspis-some of a mahogany hue, others black-also remains of Crustacea (Ceratiocaris?).
KIRKBY MOOR FLAGS.
KENDAL GROUP. (Sedgwick.)
This formation includes red calcareous flagstones and grits, sometimes in thick beds, and of coarse texture; also bands of coarse slate and tilestone.
It is placed on the horizon of the Upper Ludlow series; and it passes downwards into the Bannisdale Slate group. It extends from Benson Knot, south of Kendal, through Kirkby Moor to the Lune.
The upper part contains casts and impressions of Terebratula, Orthis, Orbicula, Pterinea, Avicula, Orthonota, Turritella, Orthoceras.
The most common and characteristic species are stated by Mr. Aveline to be Holopella gregaria, H. conica, and Chonetes lata.
The beds occur at Hay Fell, Kendal, &c.
The word 'Tilestones,' originally a local term in Caermarthenshire and Breconshire, was first used by Murchison to designate the beds between the Upper Ludlow Rocks and Old Red Sandstone.
The Ludlow Bone-bed is capped by light-coloured, thinbedded, and slightly micaceous sandstones, which have been quarried near Downton Castle, and have been called the Downton Sandstones: this term is now used for the lower portion of the Tilestones, the Ledbury Shales constituting the upper portion.1
These rocks consist of red, grey, and yellow flags, and micaceous sandstones, attaining a thickness of 100 feet in many of their features they are connected with the Old Red Sandstone.
Murchison first observed this apparent passage at Hay, in Brecon. Junctions may be observed in Caermarthenshire, Pembrokeshire, Herefordshire, Gloucestershire, Worcestershire, and Shropshire.
The town of Ledbury stands partly on these junction beds. They are quarried at Dymock.
At Malvern, the Downton sandstones are about 100 feet in thickness: they consist of sandstones and marls of different tints-red, grey, and yellow.
The beds contain Pterygotus, Hemiaspis, Beyrichia, some Phyllopods, Annelids, Lingula cornea, and other Mollusca, Onchus and Pteraspis, also traces of land plants
1 The word 'Tilestones' (happily abandoned by Sir R. I. Murchison) is altogether inappropriate. There is not a stone capable of being formed into a tile, from the Downton Sandstone to the Cornstones of Wall Hills; but there are thin muddy marls over the Downton beds, which would have been tilestones had they sufficiently hardened, and which are doubtless equivalents of the true tilestones. (Rev. W. S. Symonds.)
(probably Lycopodiaceous seeds), the oldest yet known in England and Wales.
Murchison has stated that the tilestones are visible all along the eastern frontier of the Silurian rocks, and scarcely exceed 40 or 50 feet in thickness.
This group, which rests conformably upon the Downton Sandstones, constitutes the passage-beds between the uppermost Silurian rocks and the Old Red Sandstone.
It comprises red, grey, and purple marls, shales, and sandstones, having at Malvern a thickness of 300 feet.
The section exposed near Ledbury was described by the Rev. W. S. Symonds-the beds contain Pterygotus and Eurypterus among the Crustacea; also Onchus :
Old Red Sand- Red marls with grey and reddish sandstone, Pteraspis
(Grey marl passing into red and grey marl and bluishgrey rock (Auchenaspis-grits), with Auchenaspis, Cephalaspis, Onchus, Pterygotus, Lingula, &c. 20 feet. Purple shales and thin sandstones, 34 feet.
Grey shales and grit, with Cephalaspis and Pterygotus,
Red and mottled marls, and thin sandstones with
Downton sandstone, 9 feet.