The Bishop's Frome Limestone (or Bishops Frome Limestone) is a rock unit within the Raglan Mudstone Formation of the

Old Red Sandstone Old Red Sandstone, abbreviated ORS, 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 eastern seaboard of North America. It ...

occurring in the border region between

England England is a Countries of the United Kingdom, country that is part of the United Kingdom. It is located on the island of Great Britain, of which it covers about 62%, and List of islands of England, more than 100 smaller adjacent islands. It ...

and South

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

. This limestone is a

calcrete Caliche () is a soil accumulation of soluble calcium carbonate at depth, where it precipitates and binds other materials—such as gravel, sand, clay, and silt. It occurs worldwide, in aridisol and mollisol soil orders—generally in arid or s ...

, 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 23.5 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 third and shortest period of t ...

and lower

Devonian The Devonian ( ) is a period (geology), geologic period and system (stratigraphy), system of the Paleozoic era (geology), era during the Phanerozoic eon (geology), eon, spanning 60.3 million years from the end of the preceding Silurian per ...

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 in association with it; ''Psammosteus anglicus''. The fossil remains were subsequently shown to have been wrongly identified and belong in fact to ''Traquairaspis symondsi''. The name derives from the

Herefordshire Herefordshire ( ) is a Ceremonial counties of England, ceremonial county in the West Midlands (region), West Midlands of England, bordered by Shropshire to the north, Worcestershire to the east, Gloucestershire to the south-east, and the Welsh ...

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 hamle ...

. The

British Geological Survey The British Geological Survey (BGS) is a partly publicly funded body which aims to advance Earth science, geoscientific knowledge of the United Kingdom landmass and its continental shelf by means of systematic surveying, monitoring and research. ...

has more recently redesignated it as the Chapel Point Limestone member, after a locality in

Pembrokeshire Pembrokeshire ( ; ) is a Principal areas of Wales, county in the South West Wales, south-west of Wales. It is bordered by Carmarthenshire to the east, Ceredigion to the northeast, and otherwise by the sea. Haverfordwest is the largest town and ...

where it also occurs. Its thickness is variable ranging from 2m up to 8m.

References

Geology of the United Kingdom {{mineral-stub