Speedwell Cavern
Encyclopedia
The Speedwell Cavern is one of the four show cave
s in Castleton, Derbyshire
, England
.
It consists of a horizontal lead miners' adit
(a level passageway driven horizontally into the hillside) leading to the cavern itself, a limestone
cave. The lower part of the adit and the floor of the cavern are permanently flooded, resulting in Speedwell Cavern's (locally unique) feature: the visitor makes the journey into the cave by boat (originally legged
through by the guide, but now powered by an electric motor).
At the end of the adit, the visitor alights from the boat and walks into the cave to see the fluorspar veins, the stalactite
s and stalagmite
s, and the so-called 'Bottomless Pit'. The latter is an extremely deep vertical shaft, now choked to within 20 metres (65.6 ft) of the surface by rock spoil dumped by miners. The original depth of the shaft has been estimated, from the amount of spoil placed in the shaft over the years, at around 150 metres (492.1 ft).
A connection was discovered in 1999 between the Speedwell Cavern system and Titan
, the largest natural shaft in the UK, which is 141.5 metres (464.2 ft) high.
Show cave
Show caves — also called tourist caves, public caves, and in the United States, commercial caves — are caves that are managed by a government or commercial organization and made accessible to the general public, usually for an entrance fee...
s in Castleton, Derbyshire
Derbyshire
Derbyshire is a county in the East Midlands of England. A substantial portion of the Peak District National Park lies within Derbyshire. The northern part of Derbyshire overlaps with the Pennines, a famous chain of hills and mountains. The county contains within its boundary of approx...
, 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 consists of a horizontal lead miners' adit
Adit
An adit is an entrance to an underground mine which is horizontal or nearly horizontal, by which the mine can be entered, drained of water, and ventilated.-Construction:...
(a level passageway driven horizontally into the hillside) leading to the cavern itself, a 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....
cave. The lower part of the adit and the floor of the cavern are permanently flooded, resulting in Speedwell Cavern's (locally unique) feature: the visitor makes the journey into the cave by boat (originally legged
Legging (canals)
Legging is a method of moving a boat through a canal tunnel or adit containing water.-Legging in canal tunnels:Early canal tunnels were built without a towpath as this would require a much larger bore, and hence cost more to build. Prior to the introduction of motorised boats, legging was one of...
through by the guide, but now powered by an electric motor).
At the end of the adit, the visitor alights from the boat and walks into the cave to see the fluorspar veins, the stalactite
Stalactite
A stalactite , "to drip", and meaning "that which drips") is a type of speleothem that hangs from the ceiling of limestone caves. It is a type of dripstone...
s and stalagmite
Stalagmite
A stalagmite is a type of speleothem that rises from the floor of a limestone cave due to the dripping of mineralized solutions and the deposition of calcium carbonate. This stalagmite formation occurs only under certain pH conditions within the underground cavern. The corresponding formation on...
s, and the so-called 'Bottomless Pit'. The latter is an extremely deep vertical shaft, now choked to within 20 metres (65.6 ft) of the surface by rock spoil dumped by miners. The original depth of the shaft has been estimated, from the amount of spoil placed in the shaft over the years, at around 150 metres (492.1 ft).
A connection was discovered in 1999 between the Speedwell Cavern system and Titan
Titan (cave)
Titan is a natural cavern near Castleton in the Derbyshire Peak District, and is the deepest shaft of any known cave in Britain, at . The existence of Titan was revealed in November 2006, following its discovery on 1 January 1999 after cavers discovered connections from the James Hall Over Engine...
, the largest natural shaft in the UK, which is 141.5 metres (464.2 ft) high.