The Craven Group is a
lithostratigraphical term
Term may refer to:
* Terminology, or term, a noun or compound word used in a specific context, in particular:
**Technical term, part of the specialized vocabulary of a particular field, specifically:
***Scientific terminology, terms used by scient ...
referring to the succession of
mudstone
Mudstone, a type of mudrock, is a fine-grained sedimentary rock whose original constituents were clays or muds. Mudstone is distinguished from '' shale'' by its lack of fissility (parallel layering).Blatt, H., and R.J. Tracy, 1996, ''Petrology. ...
and
limestone
Limestone ( calcium carbonate ) is a type of carbonate sedimentary rock which is the main source of the material lime. It is composed mostly of the minerals calcite and aragonite, which are different crystal forms of . Limestone forms whe ...
rock
strata
In geology and related fields, a stratum ( : strata) is a layer of rock or sediment characterized by certain lithologic properties or attributes that distinguish it from adjacent layers from which it is separated by visible surfaces known as ei ...
which occur in certain parts of northern and central England and northeast Wales in the
United Kingdom
The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain, is a country in Europe, off the north-western coast of the continental mainland. It comprises England, Scotland, Wales and North ...
within the
Chadian to
Yeadonian sub-
Stage
Stage or stages may refer to:
Acting
* Stage (theatre), a space for the performance of theatrical productions
* Theatre, a branch of the performing arts, often referred to as "the stage"
* ''The Stage'', a weekly British theatre newspaper
* Sta ...
s of the
Carboniferous
The Carboniferous ( ) is a geologic period and system of the Paleozoic that spans 60 million years from the end of the Devonian Period million years ago ( Mya), to the beginning of the Permian Period, million years ago. The name ''Carbonifero ...
Period
Period may refer to:
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* Full stop (or period), a punctuation mark
Arts, entertainment, and media
* Period (music), a concept in musical composition
* Periodic sentence (or rhetorical period), a concept ...
. Other
lithologies
The lithology of a rock unit is a description of its physical characteristics visible at outcrop, in hand or core samples, or with low magnification microscopy. Physical characteristics include colour, texture, grain size, and composition. Lit ...
including
sandstone
Sandstone is a clastic sedimentary rock composed mainly of sand-sized (0.0625 to 2 mm) silicate grains. Sandstones comprise about 20–25% of all sedimentary rocks.
Most sandstone is composed of quartz or feldspar (both silicates) ...
s,
siltstone
Siltstone, also known as aleurolite, is a clastic sedimentary rock that is composed mostly of silt. It is a form of mudrock with a low clay mineral content, which can be distinguished from shale by its lack of fissility.Blatt ''et al.'' 1980, p ...
s and
chert
Chert () is a hard, fine-grained sedimentary rock composed of microcrystalline or cryptocrystalline quartz, the mineral form of silicon dioxide (SiO2). Chert is characteristically of biological origin, but may also occur inorganically as a prec ...
occur within the group. The Group is subdivided into numerous formations, some of which previously enjoyed group status. In
stratigraphic
Stratigraphy is a branch of geology concerned with the study of rock layers (strata) and layering (stratification). It is primarily used in the study of sedimentary and layered volcanic rocks.
Stratigraphy has three related subfields: lithostrati ...
order (uppermost/youngest at top), these are:
*Bowland Shale Formation (mudstone and siltstone)
*Pendleside Limestone Formation (interbedded limestone and mudstone,
conglomerate)
*Hodderense Limestone Formation
*Hodder Mudstone Formation (limestone and mudstone)
The Craven Group unconformably overlies the
Bowland High Group and elsewhere the
Clwyd Limestone Group. It is succeeded (overlain) by the
Millstone Grit Group[British Geological Survey 1:625,000 scale geological map ''Bedrock geology: UK South'' (5th edn) BGS, Keyworth, Notts]
References
See also
Geology of Lancashire
: ''This article covers the modern ceremonial county of Lancashire which includes the boroughs of Blackpool and Blackburn with Darwen but not those southern parts of the historic county of Lancashire which have since 1974 formed a part of the coun ...
Carboniferous System of Europe
Stratigraphy of the United Kingdom
{{UK-geologic-formation-stub