The Bovey Formation is a deposit of

sand Sand is a granular material composed of finely divided mineral particles. Sand has various compositions but is defined by its grain size. Sand grains are smaller than gravel and coarser than silt. Sand can also refer to a textural class of s ...

clay Clay is a type of fine-grained natural soil material containing clay minerals (hydrous aluminium phyllosilicates, e.g. kaolin, Al2 Si2 O5( OH)4). Clays develop plasticity when wet, due to a molecular film of water surrounding the clay par ...

s and

lignite Lignite, often referred to as brown coal, is a soft, brown, combustible, sedimentary rock formed from naturally compressed peat. It has a carbon content around 25–35%, and is considered the lowest rank of coal due to its relatively low heat ...

, probably over 1000 feet thick. It lies in a

sedimentary basin Sedimentary basins are region-scale depressions of the Earth's crust where subsidence has occurred and a thick sequence of sediments have accumulated to form a large three-dimensional body of sedimentary rock. They form when long-term subsidence ...

termed the Bovey Basin which extends from Bovey Tracey to Newton Abbot in South

Devon Devon ( , historically known as Devonshire , ) is a ceremonial and non-metropolitan county in South West England. The most populous settlement in Devon is the city of Plymouth, followed by Devon's county town, the city of Exeter. Devon is ...

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 ...

. The Bovey Basin lies along the line of the

Sticklepath fault Sticklepath is a village on Dartmoor, in the county of Devon, England. It gives its name to one of the most important geological faults in south-west England, thought to have originated during the Tertiary period and known variously as the Stick ...

and owes its existence to subsidence along this fault. The deposit is the result of the degradation of the neighbouring Dartmoor

granite Granite () is a coarse-grained (phaneritic) intrusive igneous rock composed mostly of quartz, alkali feldspar, and plagioclase. It forms from magma with a high content of silica and alkali metal oxides that slowly cools and solidifies undergro ...

; it was laid down in river flood plains and lakes during the late

Eocene The Eocene ( ) Epoch is a geological epoch (geology), epoch that lasted from about 56 to 33.9 million years ago (mya). It is the second epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), Era. The name ''Eocene' ...

and

Oligocene The Oligocene ( ) is a geologic epoch of the Paleogene Period and extends from about 33.9 million to 23 million years before the present ( to ). As with other older geologic periods, the rock beds that define the epoch are well identified but the ...

periods. Most of the fossilised plant material in the lignite is from '' Sequoia couttsiae''. The Bovey Formation is the major source in England for ball clay – a highly plastic fine-grained kaolinitic sedimentary clay typically used by the

pottery Pottery is the process and the products of forming vessels and other objects with clay and other ceramic materials, which are fired at high temperatures to give them a hard and durable form. Major types include earthenware, stoneware and por ...

industry. Large excavations have been made for the extraction of these clays. In the past, the lignite or "Bovey Coal" was burned in local kilns; steam engines; and workmen's cottages. It was, however, not economical.

References

{{Reflist, refs= {{EB1911, inline=1 , wstitle=Bovey Beds , volume=4 , page=337 This cites: *S. Gardiner, ''Q. J. G. S,'' London, xxxv., 1879 * W. Pengelly and O. Heer, ''Phil. Trans.'', 1862 * C. Reid, ''Q. J. G. S.'' lii., 1896, p. 490, and ''loc. cit.'' liv., 1898, p 234. *A. W. Clayden, ''The History of Devonshire Scenery'' (London, 1906), pp. 159-168 Lithostratigraphy of England Oligocene Geology of Devon