In geology, the Ludlovian or Ludlow Group is the name of the uppermost subdivision of the Silurian rocks in Great Britain. This group contains the following formations in descending order: This article includes a list of works cited but its sources remain unclear because it lacks in-text citations. ... The Silurian is a major division of the geologic timescale that extends from the end of the Ordovician period, about 443. ...

1. Cilestones, Downton Castle sandstones (90 ft./27.7 m),
2. Ledbury shales 270 ft./83 m),
3. Upper Ludlow rocks (140 ft./43 m),
4. Aymestry limestone (up to 40 ft./12.3 m),
5. Lower Ludlow rocks (350 to 780 ft./108 m-240 m).

The Ludlow group is essentially shaly in character, except towards the top, where the beds become more sandy and pass gradually into the Old Red Sandstone. The Aymestry limestone, which is irregular in thickness, is sometimes absent, and where the underlying Wenlock limestones are absent the shales of the Ludlow group graduate, downwards into the Wenlock shales. The group is typically developed between Ludlow and Aymestry, and it occurs also in the detached Silurian areas between Dudley and the mouth of the Severn. Shale Shale is a fine-grained sedimentary rock whose original constituents were clays or muds. ... Patterns in the sand Sand is a granular material made up of fine rock particles. ... -1... , Ludlow is a town in Shropshire, England situated close to the border with Wales in The Welsh Marches. ... Map sources for Dudley at grid reference SO9390 Dudley is a town in the West Midlands, England. ... The Severn is the name of a river in the United Kingdom. ...

The Lower Ludlow rocks are mainly grey, greenish and brown mudstones and sandy and calcareous shales. They contain an abundance of fossils. The series has been zoned by means of the Graptolites by E. M. R. Wood; the following in ascending order, are the zonal forms: Mudstone is a fine-grained sedimentary rock whose original constituents were clays or muds. ... Calcareous formed from or containing a high proportion of Calcium carbonate. ... FOSSIL is a standard for allowing serial communication for telecommunications programs under DOS. FOSSIL is an acronym for Fido Opus Seadog Standard Interface Layer. ...

1. Monograptus vulgaris,
2. M. Nilssoni,
3. M. scanicus,
4. M. tumescens and
5. M. leintwardinensis.

Cyathaspis ludensis, the earliest British vertebrate fossil, was found in these rocks at Leintwardine in Herefordshire, a noted fossil locality. Trilobites are numerous (Phacops caudatus, Lichas anglicus, Homolonotus delphinocephalus, Calymene Blumenbachii); brachiopods (Leptaena rhomboidalis, Rhynchonella Wilsoni, Atrypa reticularis}, pelecypods (Cardiola interrupts, Ctenodonta sulcata) and gasteropods and cephalopods (many species of Orthoceras and also Gomphoceras, Trochoceras) are well represented. Other fossils are Ceratiocaris , Pterygotus, Protaster, Palaeocoma and Palaeodiscus. This article does not cite any references or sources. ... Location within the British Isles. ... Herefordshire is a historic and ceremonial county and unitary district (known as County of Herefordshire) in the West Midlands region of England. ... Orders Agnostida Redlichiida Corynexochida Lichida Nektaspida? Phacopida Proetida Asaphida Harpetida Ptychopariida Trilobites are extinct arthropods in the class Trilobita. ... Subphyla and classes See Classification Brachiopods (from Latin brachium, arm + New Latin -poda, foot) are a phylum of animals. ... Orders Subclass Protobranchia Solemyoida Nuculoida Subclass Pteriomorphia - oysters, mussels Arcoida Mytiloida Pterioida Subclass Paleoheterodonta Trigoinoida Unionoida - freshwater mussels Subclass Heterodonta - clams, zebra mussels Veneroida Myoida Subclass Anomalosdesmata Pholadomyoida Bivalves are molluscs belonging to the class Bivalvia. ... Subclass Subclass Eogastropoda     Patellogastropoda Subclass Orthogastropoda   Superorder Cocculiniformia   Superorder Hot Vent Taxa     Neomphaolida   Superorder Vetigastropoda   Superorder Neritaemorphi     Neritopsina   Superorder Caenogastropoda     Architaenioglossa     Sorbeoconcha   Superorder Heterobranchia     Heterostropha     Opisthobranchia     Pulmonata The gastropods, or univalves, are the largest and most successful class of mollusks, with 60,000-75,000 species, and second largest class... Orders Subclass Nautiloidea †Plectronocerida †Ellesmerocerida †Actinocerida †Pseudorthocerida †Endocerida †Tarphycerida †Oncocerida †Discosorida Nautilida †Orthocerida †Ascocerida †Bactritida Subclass †Ammonoidea †Goniatitida †Ceratitida †Ammonitida Subclass Coleoidea †Belemnoidea †Aulacocerida †Belemnitida †Hematitida †Phragmoteuthida Neocoleoidea (most living cephalopods) ?†Boletzkyida Sepiida Sepiolida Spirulida Teuthida Octopoda Vampyromorphida The cephalopods (Greek plural (kephalópoda); head-foot) are the mollusk class...

The Upper Ludlow rocks are mainly soft mudstones and shales with some harder sandy beds capable of being worked as building-stones. These sandy beds are often found covered with ripple-marks and annelid tracks; one of the uppermost sandy layers is known as the " Fucoid bed " from the abundance of the seaweed-like impressions it bears. At the top of this sub-group, near Ludlow, a brown layer occurs, from a quarter of an inch to 4 in. (63 mm to 100 mm) in thickness, full of the fragmentary remains of fish associated with those of Pterygotus and mollusca. This layer, known as the " Ludlow Bone bed," has been traced over a very large area (see Bone Bed). The common fossils include plants (Actinophyllum, Chondrites), ostracods, phyllocarids, eurypterids, trilobites (less common than in the older groups), numerous brachiopods (Lingula minima, Chonetes striatella), gasteropods, pelecypods and cephalopods (Orthoceras bullatum). Fish include Cephalaspis, Cyathaspis, Auchenaspis. The Tilestones, Downton Castle Sandstone and Ledbury shales are occasionally grouped together under the term Downtonian. They are in reality passage beds between the Silurian and Old Red Sandstone, and were originally placed in the latter system by Sir R. I. Murchison. They are mostly grey, yellow or red micaceous, shaly sandstones. Lingula cornea, Platyschisma helicites and numerous phyllocarids and ostracods occur among the fossils. Classes and subclasses Class Polychaeta (paraphyletic?) Class Clitellata*    Oligochaeta - earthworms, etc. ... Pterygotus is the largest known eurypterid, or sea scorpion. ... Classes Caudofoveata Aplacophora Polyplacophora Monoplacophora Bivalvia Scaphopoda Gastropoda Cephalopoda † Rostroconchia † Helcionelloida † ?Bellerophontidae The molluscs (British spelling) or mollusks (American spelling) are members of the large and diverse phylum Mollusca, which includes a variety of familiar animals well-known for their decorative shells or as seafood. ... A bone bed is any stratum or deposit which contains bones of whatever kind; not a formal term, it tends to be used more of especially dense collections. ...

In Denbighshire and Merionethshire the upper portion of the Denbighshire Grits belongs to this horizon: viz. those from below upwards, the Nantglyn Flags, the Upper Grit beds, the Monograptus leintwardinensis beds and the Dinas Bran beds. In the Silurian area of the Lake district the Coldwell beds, forming the upper part of the Coniston Flags, are the equivalents of the Lower Ludlow; they are succeeded by the Coniston Grits (4,000 ft./1,230 m), the Bannisdale Slates (5200 ft./1,600 m) and the Kirkby Moor Flags (2,000 ft./615 m). Denbighshire (Welsh: Sir Ddinbych) is a county in North Wales. ... Merionethshire (Meirionnydd in Welsh) is a traditional county of Wales. ...

In the Silurian areas of southern Scotland, the Ludlow rocks are represented in the Kirkcudbright Shore and Riccarton district by the Raeberry Castle beds and Balmae Grits (500-750 ft.). In the northern belt Lanarkshire and the Pentland Hillsthe lower portion (or Ludlovian) consists of mudstones, flaggy shales and greywackes; but the upper (or Downtonian) part is made up principally of thick red and yellow sandstones and conglomerates with green mudstones. The Ludlow rocks of Ireland include the " Salrock beds " of County Galway and the "Croagmarhin beds" of Dingle promontory. Motto (Latin) No one provokes me with impunity Cha togar mfhearg gun dioladh (Scottish Gaelic) Wha daur meddle wi me?(Scots)1 Anthem (Multiple unofficial anthems) Scotlands location in Europe Capital Edinburgh Largest city Glasgow Official languages English (de facto)1; Gaelic[1]2 and Scots3 (recognised minority... WGS-84 (GPS) Coordinates: , Statistics Province: Connacht County: Dáil Éireann: Galway West European Parliament: North-West Dialling Code: 091 Postal District(s): G Area: 50. ...

References

• This article incorporates text from the Encyclopædia Britannica Eleventh Edition, a publication now in the public domain.