Hushing
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Hushing is an ancient and historic
mining Mining is the Resource extraction, extraction of valuable geological materials and minerals from the surface of the Earth. Mining is required to obtain most materials that cannot be grown through agriculture, agricultural processes, or feasib ...
method using a flood or torrent of
water Water is an inorganic compound with the chemical formula . It is a transparent, tasteless, odorless, and Color of water, nearly colorless chemical substance. It is the main constituent of Earth's hydrosphere and the fluids of all known liv ...
to reveal mineral veins. The method was applied in several ways, both in prospecting for ores, and for their exploitation. Mineral veins are often hidden below soil and sub-soil, which must be stripped away to discover the ore veins. A flood of water is very effective in moving soil as well as working the ore deposits when combined with other methods such as fire-setting. Hushing was used during the formation and expansion of the
Roman Empire The Roman Empire ruled the Mediterranean and much of Europe, Western Asia and North Africa. The Roman people, Romans conquered most of this during the Roman Republic, Republic, and it was ruled by emperors following Octavian's assumption of ...
from the 1st century BC on to the end of the empire. It was also widely used later, and apparently survived until modern times where the cost of explosives was prohibitive. It was widely used in the United States, where it was known as "booming". A variant known as
hydraulic mining Hydraulic mining is a form of mining that uses high-pressure jets of water to dislodge rock material or move sediment.Paul W. Thrush, ''A Dictionary of Mining, Mineral, and Related Terms'', US Bureau of Mines, 1968, p.560. In the placer mining of ...
where jets or streams of water are used to break down deposits, especially of alluvial
gold Gold is a chemical element; it has chemical symbol Au (from Latin ) and atomic number 79. In its pure form, it is a brightness, bright, slightly orange-yellow, dense, soft, malleable, and ductile metal. Chemically, gold is a transition metal ...
and alluvial tin, is commonly used.


History

The method is well described by
Pliny the Elder Gaius Plinius Secundus (AD 23/24 79), known in English as Pliny the Elder ( ), was a Roman Empire, Roman author, Natural history, naturalist, and naval and army commander of the early Roman Empire, and a friend of the Roman emperor, emperor Vesp ...
in Book XXXIII of his ''Naturalis Historia'' from the 1st century AD. He distinguishes the use of the method for prospecting for ore and use during mining itself. It was used during the Roman period for
hydraulic mining Hydraulic mining is a form of mining that uses high-pressure jets of water to dislodge rock material or move sediment.Paul W. Thrush, ''A Dictionary of Mining, Mineral, and Related Terms'', US Bureau of Mines, 1968, p.560. In the placer mining of ...
of alluvial
gold Gold is a chemical element; it has chemical symbol Au (from Latin ) and atomic number 79. In its pure form, it is a brightness, bright, slightly orange-yellow, dense, soft, malleable, and ductile metal. Chemically, gold is a transition metal ...
deposits, and in opencast vein mining, for removal of rock debris, created by mechanical attack and fire-setting. He describes how tanks and reservoirs are built near the suspected veins, filled with water from an aqueduct, and the water suddenly released from a sluice-gate onto the hillside below, scouring the soil away to reveal the bedrock and any veins occurring there.


Method

The power behind a large release of water is very great, especially if it forms a single water wave, and is well known as a strong force in
coastal erosion Coastal erosion is the loss or displacement of land, or the long-term removal of sediment and rocks along the coastline due to the action of Wind wave, waves, Ocean current, currents, tides, wind-driven water, waterborne ice, or other impacts ...
and river erosion. Such a wave could be created by a sluice gate covering one end of the reservoir, possibly a permanent fixture such as a swinging flap or a rising gate. The size of the tank controlled the height of the wave and its volume. Hushing was most effective when used on steep ground such as the brow of a hill or mountain, the force of falling water lessening as the slope becomes smaller. The rate of attack would be controlled by the water supply, and perhaps more difficult the higher the deposit to be cleared. If veins of ore were found using the method, then hushing could also remove the rock debris created when attacking the veins. Pliny also describes the way hillsides could be undermined, and then collapsed to release the ore-bearing material. The Romans developed the method into a sophisticated way of extracting large alluvial gold deposits such as those at Las Médulas in northern
Spain Spain, or the Kingdom of Spain, is a country in Southern Europe, Southern and Western Europe with territories in North Africa. Featuring the Punta de Tarifa, southernmost point of continental Europe, it is the largest country in Southern Eur ...
, and for hard rock gold veins such as those at Dolaucothi in
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 ...
. The development of the mine at Dolaucothi shows the versatility of the method in finding and then exploiting ore deposits. There are the remains of numerous tanks and reservoirs still to be seen at the site, one example being shown at right. It was a small tank built for prospection on the north side of the isolated opencast north of the main mine. It was presumably built to prospect the ground to one side of the opencast for traces of the gold-bearing veins extending to the north. It failed to find the veins here, so was abandoned. It probably precedes the construction of the 7 mile long aqueduct supplying the main site, and was fed by a small leat from a tributary of the river Cothi about a mile further north up the valley. The method could be applied to any ore type, and succeeded best in hilly terrain. The Romans were well experienced in building the long aqueducts needed to supply the large volumes of water needed by the method, and construction was probably directed by army engineers.


Earlier evidence

The earlier history of the method is obscure, although there is an intriguing reference by
Strabo Strabo''Strabo'' (meaning "squinty", as in strabismus) was a term employed by the Romans for anyone whose eyes were distorted or deformed. The father of Pompey was called "Gnaeus Pompeius Strabo, Pompeius Strabo". A native of Sicily so clear-si ...
writing ca 25 BC in his ''
Geographica The ''Geographica'' (, ''Geōgraphiká''; or , "Strabo's 17 Books on Geographical Topics") or ''Geography'', is an encyclopedia of geographical knowledge, consisting of 17 'books', written in Greek in the late 1st century BC, or early 1st cen ...
'', Book IV, Chapter 6, to gold extraction in the Val d'Aosta in the
Alps The Alps () are some of the highest and most extensive mountain ranges in Europe, stretching approximately across eight Alpine countries (from west to east): Monaco, France, Switzerland, Italy, Liechtenstein, Germany, Austria and Slovenia. ...
. He describes the problem gold miners had with a local tribe because of the great volumes of water they had taken from the local river, reducing it to a trickle and so affecting the local farmers. Whether or not they used the water for hushing remains unknown, but it seems possible because the method requires large volumes of water to be operated. Later, when the Romans assumed control of the mining operations, the locals charged them for using the water. The tribe occupied the higher mountains and controlled the water sources, and had not yet been subdued by the Romans: The historian
Polybius Polybius (; , ; ) was a Greek historian of the middle Hellenistic period. He is noted for his work , a universal history documenting the rise of Rome in the Mediterranean in the third and second centuries BC. It covered the period of 264–146 ...
, who lived from 220 to 170 BC, was writing much earlier in ''The Histories'' (Book 34), and he records that gold mining in the Alpine region was so successful that the price of gold in Italy fell by a third during this period. From his description of large nuggets, and the find being made only two feet below the ground level, with deposits reaching down to 15 feet, it is likely to have been an alluvial deposit where water methods such as hushing would have been very effective. Modern attempts to identify the mines point to one especially large ancient gold mine at Bessa in Northern
Italy Italy, officially the Italian Republic, is a country in Southern Europe, Southern and Western Europe, Western Europe. It consists of Italian Peninsula, a peninsula that extends into the Mediterranean Sea, with the Alps on its northern land b ...
. It appears to have been worked intensively in pre-Roman days and continued to expand with Roman involvement. The scale of the aqueducts there seems to support Strabo's comments.


Later examples

The technique appears to have been neglected through the medieval period, because
Georgius Agricola Georgius Agricola (; born Georg Bauer; 24 March 1494 – 21 November 1555) was a German Humanist scholar, mineralogist and metallurgist. Born in the small town of Glauchau, in the Electorate of Saxony of the Holy Roman Empire, he was b ...
, writing in the 16th century in his '' De re metallica'', does not mention hushing at all, although he does describe many other uses of water power, especially for washing ore and driving watermills. However, the technique was used on a large scale in the
lead Lead () is a chemical element; it has Chemical symbol, symbol Pb (from Latin ) and atomic number 82. It is a Heavy metal (elements), heavy metal that is density, denser than most common materials. Lead is Mohs scale, soft and Ductility, malleabl ...
mines of northern Britain from at least Elizabethan times onwards. The method was described in some detail by Westgarth Forster in his book ''A Treatise on a Section of the Strata from Newcastle upon Tyne to the Mountain of Cross Fell in Cumberland'' (1809), and also in the 1842
Royal Commission A royal commission is a major ad-hoc formal public inquiry into a defined issue in some monarchies. They have been held in the United Kingdom, Australia, Canada, New Zealand, Norway, Malaysia, Mauritius and Saudi Arabia. In republics an equi ...
on Children in Mines in relation to children being used in the lead mines of the
Pennines The Pennines (), also known as the Pennine Chain or Pennine Hills, are a range of highland, uplands mainly located in Northern England. Commonly described as the "Vertebral column, backbone of England" because of its length and position, the ra ...
. The remnants of hush gullies are visible at many places in the Pennines and at other locations such as the extensive lead mines at Cwmystwyth in
Ceredigion Ceredigion (), historically Cardiganshire (, ), is a Principal areas of Wales, county in the West Wales, west of Wales. It borders Gwynedd across the River Dyfi, Dyfi estuary to the north, Powys to the east, Carmarthenshire and Pembrokeshire t ...
, Wales, and at the Stiperstones in
Shropshire Shropshire (; abbreviated SalopAlso used officially as the name of the county from 1974–1980. The demonym for inhabitants of the county "Salopian" derives from this name.) is a Ceremonial counties of England, ceremonial county in the West M ...
. Another notable example is the Great Dun Fell hush gully near Cross Fell,
Cumbria Cumbria ( ) is a ceremonial county in North West England. It borders the Scottish council areas of Dumfries and Galloway and Scottish Borders to the north, Northumberland and County Durham to the east, North Yorkshire to the south-east, Lancash ...
, probably formed in the
Georgian era The Georgian era was a period in British history from 1714 to , named after the House of Hanover, Hanoverian kings George I of Great Britain, George I, George II of Great Britain, George II, George III and George IV. The definition of the Geor ...
in the search for lead and silver. This gully is about 100 feet deep, carries a small stream, and is a prominent landmark on the bleak moors. The dams used to store the water are also often visible at the head of the stream. Although the term "hushing" was not used in south-west England, there is a reference to the technique being used at Tregardock in North Cornwall, where in around 1580 mine adventurers used the method to work a lead-silver deposit, although lives were lost in the attempt. Phil Newman, writing in 2011, states that there is possible archaeological evidence for use of the technique at two sites on Dartmoor in
Devon Devon ( ; historically also known as Devonshire , ) is a ceremonial county in South West England. It is bordered by the Bristol Channel to the north, Somerset and Dorset to the east, the English Channel to the south, and Cornwall to the west ...
, in the form of channels running downhill that apparently originate from contour-following leats, though he says research is needed for confirmation. In south-eastern Lancashire hushing was used to extract limestone from the glacial boulder clay so that it could be used to make lime for agriculture, mortar, plaster and limewash. Bennett notes leases of land for this purpose in the 17th and 18th centuriesBennett, W. (1948) ''A History of Burnley'' Vol.2 p. 97. and remains can still be seen at sites like Shedden Clough. Hushing for limestone seems to have been limited to the eastern side of the Pennine ridge, between Burnley and the Cliviger Gorge, and probably occurred here because of the cost of obtaining supplies from further away, as well as the suitability of the boulder clay and the availability of water supplies. The technique was also used during alluvial gold mining in Africa, at least until the 1930s, when it was described by Griffith in his book ''Alluvial Mining'' (2nd Ed., 1960). The water outlet could be controlled by an automatic system which allowed water to flow through the sluice gate when the overflow triggered a release mechanism.


See also

* Dartmoor tin-mining * Derbyshire lead mining history * Dolaucothi Gold Mines * Mining in Cornwall * Placer mining * Roman engineering * Roman technology * Roman mining


Notes


References

* Oliver Davies, ''Roman Mines in Europe'', Clarendon Press (Oxford), 1935. * Jones G. D. B., I. J. Blakey, and E. C. F. MacPherson, ''Dolaucothi: the Roman aqueduct'', Bulletin of the Board of Celtic Studies 19 (1960): 71-84 and plates III-V. * Lewis, P. R. and G. D. B. Jones, ''The Dolaucothi gold mines, I: the surface evidence'', The Antiquaries Journal, 49, no. 2 (1969): 244-72. * Lewis, P. R. and G. D. B. Jones, ''Roman gold-mining in north-west Spain'', Journal of Roman Studies 60 (1970): 169-85. * Lewis, P. R., ''The Ogofau Roman gold mines at Dolaucothi'', The National Trust Year Book 1976-77 (1977). * Annels, A and Burnham, BC, ''The Dolaucothi Gold Mines'', University of Wales, Cardiff, 3rd Ed (1995). * Hodge, A.T. (2001). ''Roman Aqueducts & Water Supply'', 2nd ed. London: Duckworth. * Timberlake, S, ''Early leats and hushing remains: suggestions and disputes for roman mining and prospection for lead'', Bulletin of the Peak District mines Historical Society, 15 (2004), 64 ff.


External links


Royal Commission on Children in Mines describes hushing in 1842Roman technologyHushing in Yorkshire minesGreat Dun Fell hush gulleyHushing in Gunnerdale, Yorkshire
{{Webarchive, url=https://web.archive.org/web/20090116062652/http://www.mylearning.org/jpage.asp?jpageid=413&journeyid=119 , date=16 January 2009
Hushing as used at Cwmystwyth mineRemains of hushing systems in Wales by TimberlakeShedings at Shedden CloughShedden Clough Hushings
Traditional mining History of mining Roman aqueducts outside Rome Aqueducts in the United Kingdom Hydraulic engineering