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34-401: The Mercia Mudstone Group is now divided into five formations recognised and mappable across its entire outcrop and subcrop . The formations are a mix of mudstones , siltstones , sandstones and halites . Historically this sequence of rocks has been subdivided in different ways with different names in each of the basinal areas in which it is found. Increasing knowledge of the sequences and

68-677: A continuous line along the top edge with lines protruding down; outcrops have a continuous line around each area of bare rock. An outcrop example in California is the Vasquez Rocks , familiar from location shooting use in many films , composed of uplifted sandstone . Yana is another example of outcrops, located in Uttara Kannada district in Karnataka , India . Carnian The Carnian (less commonly, Karnian )

102-600: A marine-influenced environment. The Arden Sandstone is also known as North Curry Sandstone which is used as a building material in Somerset . The formation includes several members which formerly enjoyed 'formation' status. This sequence was formerly known as the Eldersfield Mudstone Formation in the Worcester and Knowle basins and as the (combined) Edwalton, Gunthorpe and Radcliffe formations on

136-546: A record of relative changes within geologic strata . Accurate description, mapping, and sampling for laboratory analysis of outcrops made possible all of the geologic sciences and the development of fundamental geologic laws such as the law of superposition , the principle of original horizontality , principle of lateral continuity , and the principle of faunal succession . On Ordnance Survey maps in Great Britain , cliffs are distinguished from outcrops: cliffs have

170-588: A source of potential confusion. An example might be the Arden Sandstone Formation which previously enjoyed lower status as a member and also higher status as a group . The group crops out widely across England, representing deposition within numerous Triassic basins, some of which are physically connected at depth. From the south there is an almost continuous outcrop from the Wessex Basin of east Devon , Somerset and Dorset , through

204-713: A three-substage organization of the stage as follows: In the Tethys domain , the Carnian Stage contains six ammonite biozones: The Otischalkian land vertebrate faunachron corresponds to the early late Carnian, while the Adamanian land vertebrate faunachron corresponds to the latest Carnian. The paleogeography of the Carnian was basically the same as for the rest of the Triassic. Most continents were merged into

238-878: Is Anisian in age. Formerly known as the Lower Keuper Saliferous Beds and as the Northwich Halite Formation (named from the town of Northwich ), this member is Anisian in age. Formerly known as the Lower Keuper Marl, lower mudstone and also as the Bollin Mudstone Formation (named from the River Bollin in east Cheshire ), this member is (?Scythian to) Anisian in age. In West Cumbria, the Sidmouth Mudstone Formation

272-713: Is Anisian to Ladinian in age. The Tarporley Siltstone Formation (named from the Cheshire village of Tarporley ) is Anisian in age and comprises siltstones, mudstones and sandstones. The thickness of the sequence varies from 20 m in parts of the East Midlands to around 220m in the Cheshire Basin. It is encountered in older literature under various guises but commonly as the Keuper Waterstones or simply Waterstones. These rocks feature prominently along

306-769: Is Ladinian to Carnian in age. Formerly known as (the upper part of) the Middle Keuper Marl and as the Wych Mudstone Formation (named from the Wych Brook on the Cheshire/Flintshire/Shropshire border), this member is Anisian to Ladinian in age. Formerly known as (the lower part of) the Middle Keuper Marl and as the Byley Mudstone Formation (named from the Cheshire village of Byley ), this member

340-703: Is divided thus: Formerly known as the Singleton Mudstone Formation (named from the Lancashire village of Singleton ), this member is Early Triassic to Anisian in age. Formerly known as the Kirkham Mudstone Formation (named from the small Lancashire town of Kirkham ), this member is Anisian to Ladinian in age. Formerly known as the Preesall Salt (named from the Lancashire village of Preesall ), this member

374-631: Is given below. Many Carnian vertebrates are found in Santa Maria Formation rocks of the Paleorrota geopark . The lower Carnian fauna of the San Cassiano Formation ( Dolomites , northern Italy ) has been studied since the 19th century. Fossiliferous localities are many, and are distributed mostly in the surroundings of Cortina d'Ampezzo and in the high Badia Valley, near the village of San Cassiano , after which

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408-402: Is rapid and exceeds the weathering rate such as on steep hillsides, mountain ridges and tops, river banks, and tectonically active areas. In Finland , glacial erosion during the last glacial maximum (ca. 11000 BC), followed by scouring by sea waves, followed by isostatic uplift has produced many smooth coastal and littoral outcrops. Bedrock and superficial deposits may also be exposed at

442-735: Is the lowermost stage of the Upper Triassic Series (or earliest age of the Late Triassic Epoch ). It lasted from 237 to 227 million years ago (Ma) . The Carnian is preceded by the Ladinian and is followed by the Norian . Its boundaries are not characterized by major extinctions or biotic turnovers, but a climatic event (known as the Carnian pluvial episode characterized by substantial rainfall) occurred during

476-915: The Bristol / South Wales area and the Worcester and Knowle Basins into the English Midlands and including the Needwood Basin of Staffordshire . Northwards the outcrop splits either side of the Pennines where deposition took place across the East Midlands Shelf of Nottinghamshire and through Yorkshire to the North Sea coast at Hartlepool . A western arm includes the Stafford and Cheshire basins, West Lancashire and

510-550: The Mid Cheshire Ridge where they form the summits of such hills as Eddisbury Hill and the Old Pale and the high ground around Tarporley and Utkinton together with small tracts of hilly country around Runcorn and Warrington . The Malpas Sandstone Member is distinguished within this formation. Outcrop An outcrop or rocky outcrop is a visible exposure of bedrock or ancient superficial deposits on

544-479: The Santa Maria Formation (e.g. Staurikosaurus and Buriolestes ) originated during the Carnian, around 230 Ma . In this stage the archosaurs became the dominant faunas in the world, evolving into groups such as the phytosaurs , rhynchosaurs , aetosaurs , and rauisuchians . The first dinosaurs (and the pterosaur Carniadactylus ) also appeared in this stage, and though at the time they were small and insignificant, they diversified rapidly and would dominate

578-598: The Carlisle Basin—the latter are connected at depth beneath the Irish Sea . The group is most thickly developed within the Cheshire Basin (which also extends southwards into north Shropshire) where it attains a thickness in excess of 1,350 m. The formation is named from the village of Blue Anchor on the coast of west Somerset. It consists largely of green to grey mudstones and siltstones (which gave rise to

612-456: The Carnian (the base of the Norian) is at the bases of the ammonite biozones of Klamathites macrolobatus or Stikinoceras kerri and the conodont biozones of Metapolygnathus communisti or Metapolygnathus primitius . There is no established, standard usage for the Carnian subdivisions, thus, while in some regional stratigraphies a two-substage subdivision is common: others prefer

646-711: The Carnian and seems to be associated with important extinctions or biotic radiations. Another extinction occurred at the Carnian-Norian boundary, ending the Carnian age. The Carnian was named in 1869 by Mojsisovics . It is unclear if it was named after the Carnic Alps or after the Austrian region of Carinthia ( Kärnten in German) or after the Carnia historical region in northeastern Italy. The name, however,

680-475: The Earth's surface due to human excavations such as quarrying and building of transport routes. Outcrops allow direct observation and sampling of the bedrock in situ for geologic analysis and creating geologic maps . In situ measurements are critical for proper analysis of geological history and outcrops are therefore extremely important for understanding the geologic time scale of earth history. Some of

714-639: The East Midlands Shelf. In the Cheshire Basin it supersedes the former Bollin Mudstone, Northwich Halite, Wych Mudstone, Byley Mudstone and Wilkesley Halite formations, each of which is now accorded 'member' status. It is of Anisian through Ladinian to Carnian age. Formerly known as the Upper Keuper Saliferous Beds and as the Wilkesley Halite Formation (named from the Cheshire hamlet of Wilkesley ), this member

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748-529: The base of the upper Carnian (Tuvalian). The bivalve genus Halobia , a bottom-dweller of deep sea environments, differentiated from Daonella at the beginning of this age. Scleractinian coral reefs, i.e., reefs with corals of the modern type, became relatively common for the first time in the Carnian. The earliest unequivocal dinosaurs , such as those from the Ischigualato Formation (e.g. Herrerasaurus and Eoraptor ) and those from

782-892: The earlier name of this sequence, the Tea-green Marls) and varies from around 5 m to 67 m in thickness. Though common to all other areas, the Blue Anchor Formation is absent through erosion in the Stafford Basin and in Lancashire. It is of late Norian to early Rhaetian age. It is overlain by the Westbury Formation of the Penarth Group which represents widespread inundation of the Triassic basins as global sea levels rose. The formation consists of red-brown mudstones and siltstones in which gypsum / anhydrite occurs as beds, veins and nodules. It

816-553: The east Devon coast, is of Norian age, i.e. 216–204 mya. The formation is named after the Forest of Arden in Warwickshire. It consists of a 2 m to 24 m thickness of mudstones, siltstones and sandstones with occasional pebble beds. It generally has a more greenish grey colour than the formations above and below it though it is not readily distinguishable within the sequence in Cheshire. it has locally yielded fossils suggestive of

850-505: The fauna for the rest of the Mesozoic . On the other hand, the therapsids , which included the ancestors of mammals , decreased in both size and diversity, and would remain relatively small until the extinction of the dinosaurs. Conodonts were present in Triassic marine sediments. Paragondolella polygnathiformis appeared at the base of the Carnian Stage, and is considered a characteristic species. A partial list of Carnian vertebrates

884-401: The first abundant occurrences of calcareous nanoplankton, a morphological group including the coccolithophores . There are a few invertebrates which are typical and characteristic of the Carnian. Among molluscs, the ammonoid genus Trachyceras is exclusive to the lower Carnian (i.e., Julian of the two-substages subdivision, see above). The family Tropitidae and the genus Tropites appear at

918-541: The formation was named. This fauna is extremely diverse, including ammonoids, gastropods, bivalves, echinoderms, calcareous sponge , corals, brachiopods , and a variety of less common fossils. A collection of this fauna is exposed in the "Museo delle Regole", a museum in Cortina d'Ampezzo. The Ischigualasto Formation of the Ischigualasto-Villa Unión Basin in northwestern Argentina yielded

952-492: The more recent development of seamless electronic mapping by the British Geological Survey (BGS) necessitated a reappraisal of these divisions. A report published by BGS in 2008 recommended the abandonment of previous divisions and naming schemes in favour of a simpler approach which, having now been adopted, is set out below. Older schemes will remain in maps and literature well into the future, providing

986-518: The present one. As for most of the Mesozoic, there were no ice caps. Climate was mostly arid in the tropics, but an episode of wet tropical climate is documented at least in the Paleo-Tethys. This putative climatic event is called the " Carnian Pluvial Event ", its age being between latest early Carnian (Julian) and the beginning of late Carnian (Tuvalian). In the marine realm, the Carnian saw

1020-537: The supercontinent Pangaea , and there was a single global ocean, Panthalassa . The global ocean had a western branch at tropical latitudes called Paleo-Tethys . The sediments of Paleo-Tethys now crop out in southeastern Europe , in the Middle East , in the Himalayas , and up to the island of Timor . The extreme land-sea distribution led to "mega-monsoons", i.e., an atmospheric monsoon regime more intense than

1054-461: The surface of the Earth and other terrestrial planets . Outcrops do not cover the majority of the Earth's land surface because in most places the bedrock or superficial deposits are covered by soil and vegetation and cannot be seen or examined closely. However, in places where the overlying cover is removed through erosion or tectonic uplift , the rock may be exposed, or crop out . Such exposure will happen most frequently in areas where erosion

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1088-468: The types of information that cannot be obtained except from bedrock outcrops or by precise drilling and coring operations, are structural geology features orientations (e.g. bedding planes, fold axes, foliation ), depositional features orientations (e.g. paleo-current directions, grading, facies changes), paleomagnetic orientations. Outcrops are also very important for understanding fossil assemblages, and paleo-environment, and evolution as they provide

1122-652: Was first used referring to a part of the Hallstatt Limestone cropping out in Austria . The base of the Carnian Stage is defined as the place in the stratigraphic record where the ammonite species Daxatina canadensis first appears. The global reference profile for the base is located at the Stuores-Wiesen near Badia in the Val Badia in the region of South Tyrol , Italy . The top of

1156-408: Was formerly known as the 'Brooks Mill Mudstone Formation' in the Cheshire Basin (and named from a location near Nantwich ), as the 'Cropwell Bishop Formation' on the 'East Midlands Shelf' and as the 'Twyning Mudstone Formation' in the Worcester and Knowle basins. It is equivalent to the 'Triton Formation' of the southern North Sea . The Branscombe Mudstone Formation, which is named from Branscombe on

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