The Bishop's Frome Limestone (or Bishops Frome Limestone) is a

rock unit A stratigraphic unit is a volume of rock of identifiable origin and relative age range that is defined by the distinctive and dominant, easily mapped and recognizable petrographic, lithologic or paleontologic features (facies) that characterize it ...

within the Raglan Mudstone Formation of the

Old Red Sandstone The Old Red Sandstone is an assemblage of rocks in the North Atlantic region largely of Devonian age. It extends in the east across Great Britain, Ireland and Norway, and in the west along the northeastern seaboard of North America. It also exte ...

occurring in the border region between

England England is a country that is part of the United Kingdom. It shares land borders with Wales to its west and Scotland to its north. The Irish Sea lies northwest and the Celtic Sea to the southwest. It is separated from continental Europe b ...

and South

Wales Wales ( cy, Cymru ) is a Countries of the United Kingdom, country that is part of the United Kingdom. It is bordered by England to the Wales–England border, east, the Irish Sea to the north and west, the Celtic Sea to the south west and the ...

. This limestone is a

calcrete Caliche () is a sedimentary rock, a hardened natural cement of calcium carbonate that binds other materials—such as gravel, sand, clay, and silt. It occurs worldwide, in aridisol and mollisol soil orders—generally in arid or semiarid regions, ...

, that is to say it originated as a soil during a break in deposition rather than being an original marine deposit. It is perhaps the most significant of all of the calcretes which occur within the uppermost

Silurian The Silurian ( ) is a geologic period and system spanning 24.6 million years from the end of the Ordovician Period, at million years ago ( Mya), to the beginning of the Devonian Period, Mya. The Silurian is the shortest period of the Paleozo ...

and lower

Devonian The Devonian ( ) is a geologic period and system of the Paleozoic era, spanning 60.3 million years from the end of the Silurian, million years ago (Mya), to the beginning of the Carboniferous, Mya. It is named after Devon, England, whe ...

sequence of rocks which constitute the Old Red Sandstone of the Anglo-Welsh Basin. It defines the boundary within the basin between the Silurian and the Devonian periods. The rock was formerly known as the Psammosteus Limestone after a characteristic fossil fish recorded from it; ''Psammosteus anglicus''. The fossil remains were subsequently shown to have been wrongly identified and belong in fact to ''Traquairaspis symondsi''. Its modern name derives from the

Herefordshire Herefordshire () is a county in the West Midlands of England, governed by Herefordshire Council. It is bordered by Shropshire to the north, Worcestershire to the east, Gloucestershire to the south-east, and the Welsh counties of Monmouthshire ...

village of

Bishop's Frome Bishop's Frome (or Bishops Frome) is a village and civil parish in eastern Herefordshire, England. The village is north-east of the city and county town of Hereford, west of Malvern and south of Bromyard. The civil parish includes the haml ...

. Its thickness is variable ranging from 2m up to 8m.

References

Geology of the United Kingdom {{mineral-stub