In geology

Geology

Geology is the science comprising the study of solid Earth, the rocks of which it is composed, and the processes by which it evolves. Geology gives insight into the history of the Earth, as it provides the primary evidence for plate tectonics, the evolutionary history of life, and past climates...

, Cornbrash was the name applied to the uppermost member of the Bathonian

Bathonian

In the geologic timescale the Bathonian is an age or stage of the Middle Jurassic. It lasted from approximately 167.7 Ma to around 164.7 Ma...

 stage of the Jurassic

Jurassic

The Jurassic is a geologic period and system that extends from about Mya to  Mya, that is, from the end of the Triassic to the beginning of the Cretaceous. The Jurassic constitutes the middle period of the Mesozoic era, also known as the age of reptiles. The start of the period is marked by...

 formation in England

England

England is a country that is part of the United Kingdom. It shares land borders with Scotland to the north and Wales to the west; the Irish Sea is to the north west, the Celtic Sea to the south west, with the North Sea to the east and the English Channel to the south separating it from continental...

. It is an old English agricultural name applied in Wiltshire

Wiltshire

Wiltshire is a ceremonial county in South West England. It is landlocked and borders the counties of Dorset, Somerset, Hampshire, Gloucestershire, Oxfordshire and Berkshire. It contains the unitary authority of Swindon and covers...

 to a variety of loose rubble or brash which, in that part of the country, forms a good soil for growing corn. The name was adopted by William Smith

William Smith (geologist)

William 'Strata' Smith was an English geologist, credited with creating the first nationwide geological map. He is known as the "Father of English Geology" for collating the geological history of England and Wales into a single record, although recognition was very slow in coming...

 for a thin band of shelly limestone

Limestone

Limestone is a sedimentary rock composed largely of the minerals calcite and aragonite, which are different crystal forms of calcium carbonate . Many limestones are composed from skeletal fragments of marine organisms such as coral or foraminifera....

 which, in the south of England, breaks up in the manner indicated. Although only a thin group of rocks (1025 feet c. 300 m), it is remarkably persistent; it may be traced from Weymouth to the Yorkshire

Yorkshire

Yorkshire is a historic county of northern England and the largest in the United Kingdom. Because of its great size in comparison to other English counties, functions have been increasingly undertaken over time by its subdivisions, which have also been subject to periodic reform...

 coast, but in north Lincolnshire

North Lincolnshire

North Lincolnshire is a unitary authority area in the region of Yorkshire and the Humber in England. For ceremonial purposes it is part of Lincolnshire....

 it is very thin, and probably dies out in the neighborhood of the Humber

Humber

The Humber is a large tidal estuary on the east coast of Northern England. It is formed at Trent Falls, Faxfleet, by the confluence of the tidal River Ouse and the tidal River Trent. From here to the North Sea, it forms part of the boundary between the East Riding of Yorkshire on the north bank...

. It appears again, however, as a thin bed in Gristhorpe Bay, Cayton Bay, Wheatcroft, Newton Dale and Langdale. In the inland exposures in Yorkshire it is difficult to follow on account of its thinness, and the fact that it passes up into dark shale

Shale

Shale is a fine-grained, clastic sedimentary rock composed of mud that is a mix of flakes of clay minerals and tiny fragments of other minerals, especially quartz and calcite. The ratio of clay to other minerals is variable. Shale is characterized by breaks along thin laminae or parallel layering...

s in many places the so-called clays of the Cornbrash, with Avicula echinata.

Fossils

The Cornbrash is a very fossil

Fossil

Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...

iferous formation; the fauna indicates a transition from the Lower to the Middle Oolite

Oolite

Oolite is a sedimentary rock formed from ooids, spherical grains composed of concentric layers. The name derives from the Hellenic word òoion for egg. Strictly, oolites consist of ooids of diameter 0.25–2 mm; rocks composed of ooids larger than 2 mm are called pisolites...

s, though it is probably more nearly related to that of the beds above than to those below. Good localities for fossils are Radipole

Radipole

Radipole is a part of the district of Weymouth and Portland in the county of Dorset, England. It was formerly an independent parish, until abolished as a separate local government unit in 1933. It remains a separate ecclesiastical parish...

 near Weymouth, Closworth

Closworth

Closworth is a village and civil parish in Somerset, England, situated five miles south of Yeovil in the South Somerset district, on the border with Dorset. The village has a population of 192....

, Wincanton

Wincanton

Wincanton is a small town in south Somerset, southwest England. The town lies on the A303 road, the main route between London and South West England, and has some light industry...

, Trowbridge

Trowbridge

Trowbridge is the county town of Wiltshire, England, situated on the River Biss in the west of the county, approximately 12 miles southeast of Bath, Somerset....

, Cirencester

Cirencester

Cirencester is a market town in east Gloucestershire, England, 93 miles west northwest of London. Cirencester lies on the River Churn, a tributary of the River Thames, and is the largest town in the Cotswold District. It is the home of the Royal Agricultural College, the oldest agricultural...

, Witney

Witney

Witney is a town on the River Windrush, west of Oxford in Oxfordshire, England.The place-name 'Witney' is first attested in a Saxon charter of 969 as 'Wyttannige'; it appears as 'Witenie' in the Domesday Book of 1086. The name means 'Witta's island'....

, Peterborough

Peterborough

Peterborough is a cathedral city and unitary authority area in the East of England, with an estimated population of in June 2007. For ceremonial purposes it is in the county of Cambridgeshire. Situated north of London, the city stands on the River Nene which flows into the North Sea...

 and Sudbrook Park

Sudbrook Park

Sudbrook Park is a historic neighborhood near Pikesville, Maryland located just northwest of the Baltimore City limits in Baltimore County.The community dates to 1889 when it was designed by American landscape architect Frederick Law Olmsted, Sr. and developed by the Sudbrook Company...

 near Lincoln

Lincoln, Lincolnshire

Lincoln is a cathedral city and county town of Lincolnshire, England.The non-metropolitan district of Lincoln has a population of 85,595; the 2001 census gave the entire area of Lincoln a population of 120,779....

. A few of the important fossils are: Waldheimia lagenalis, Pecten levis, Avicula echinata, Ostrea fiabelloides, Mycicites decurtatus, Echinobrissus clunicularis. Macrocephalites macrocephalus  is abundant in the midland counties but rarer in the south; belemnites are not known. The remains of saurians (Steneosaurus

Steneosaurus

Steneosaurus is an extinct genus of teleosaurid crocodyliform from the Early Jurassic to Early Cretaceous . Fossil specimens have been found in England, France, Germany, Switzerland and Morocco.-Species:...

) are occasionally found. The Cornbrash is of little value for building or road-making, although it is used locally; in the south of England it is not oolitic, but in Yorkshire it is a rubbly, marly, frequently ironshot oolitic limestone. In Bedfordshire

Bedfordshire

Bedfordshire is a ceremonial county of historic origin in England that forms part of the East of England region.It borders Cambridgeshire to the north-east, Northamptonshire to the north, Buckinghamshire to the west and Hertfordshire to the south-east....

it has been termed the Bedford limestone.