Hushing - AbsoluteAstronomy.com

Hushing is an ancient and historic mining

Mining

Mining is the extraction of valuable minerals or other geological materials from the earth, from an ore body, vein or seam. The term also includes the removal of soil. Materials recovered by mining include base metals, precious metals, iron, uranium, coal, diamonds, limestone, oil shale, rock...

method using a flood or torrent of water

Water

Water is a chemical substance with the chemical formula H2O. A water molecule contains one oxygen and two hydrogen atoms connected by covalent bonds. Water is a liquid at ambient conditions, but it often co-exists on Earth with its solid state, ice, and gaseous state . Water also exists in a...

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

Fire-setting

Fire-setting is a method of mining used since prehistoric times up to the Middle Ages. Fires were set against a rock face to heat the stone, which was then doused with water...

.

Hushing was used during the formation and expansion of the Roman Empire

Roman Empire

The Roman Empire was the post-Republican period of the ancient Roman civilization, characterised by an autocratic form of government and large territorial holdings in Europe and around the Mediterranean....

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

Hydraulic mining, or hydraulicking, is a form of mining that uses high-pressure jets of water to dislodge rock material or move sediment. In the placer mining of gold or tin, the resulting water-sediment slurry is directed through sluice boxes to remove the gold.-Precursor - ground...

where jets or streams of water are used to break down deposits, especially of alluvial gold

Gold

Gold is a chemical element with the symbol Au and an atomic number of 79. Gold is a dense, soft, shiny, malleable and ductile metal. Pure gold has a bright yellow color and luster traditionally considered attractive, which it maintains without oxidizing in air or water. Chemically, gold is a...

and alluvial tin

Tin

Tin is a chemical element with the symbol Sn and atomic number 50. It is a main group metal in group 14 of the periodic table. Tin shows chemical similarity to both neighboring group 14 elements, germanium and lead and has two possible oxidation states, +2 and the slightly more stable +4...

, is commonly used.

History

The method is well described by Pliny the Elder

Pliny the Elder

Gaius Plinius Secundus , better known as Pliny the Elder, was a Roman author, naturalist, and natural philosopher, as well as naval and army commander of the early Roman Empire, and personal friend of the emperor Vespasian...

in Book XXXIII of his Naturalis Historia

Naturalis Historia

The Natural History is an encyclopedia published circa AD 77–79 by Pliny the Elder. It is one of the largest single works to have survived from the Roman Empire to the modern day and purports to cover the entire field of ancient knowledge, based on the best authorities available to Pliny...

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

of alluvial gold

Gold

deposits, and in opencast

Opencast

Opencast is a term to describe audio and video content, primarily in an academic context. It combines the terms "Open" for Open Source and/or Open Access and "Broadcast"...

vein mining, for removal of rock debris, created by mechanical attack and fire-setting

Fire-setting

Fire-setting is a method of mining used since prehistoric times up to the Middle Ages. Fires were set against a rock face to heat the stone, which was then doused with water...

. 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

Coastal erosion is the wearing away of land and the removal of beach or dune sediments by wave action, tidal currents, wave currents, or drainage...

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

Gold

deposits such as those at Las Medulas

Las Médulas

Las Médulas is a historical site near the town of Ponferrada in the region of El Bierzo , which used to be the most important gold mine in the Roman Empire...

in northern Spain

Spain

Spain , officially the Kingdom of Spain languages]] under the European Charter for Regional or Minority Languages. In each of these, Spain's official name is as follows:;;;;;;), is a country and member state of the European Union located in southwestern Europe on the Iberian Peninsula...

, and for hard rock gold veins such as those at Dolaucothi in Wales

Wales

Wales is a country that is part of the United Kingdom and the island of Great Britain, bordered by England to its east and the Atlantic Ocean and Irish Sea to its west. It has a population of three million, and a total area of 20,779 km²...

. 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 left. 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

Aqueduct

An aqueduct is a water supply or navigable channel constructed to convey water. In modern engineering, the term is used for any system of pipes, ditches, canals, tunnels, and other structures used for this purpose....

supplying the main site, and was fed by a small leat

Leat

A leat is the name, common in the south and west of England and in Wales, for an artificial watercourse or aqueduct dug into the ground, especially one supplying water to a watermill or its mill pond...

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

Ancient Rome

Ancient Rome was a thriving civilization that grew on the Italian Peninsula as early as the 8th century BC. Located along the Mediterranean Sea and centered on the city of Rome, it expanded to one of the largest empires in the ancient world....

were well experienced in building the long aqueduct

Aqueduct

s needed to supply the large volumes of water needed by the method, and 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, also written Strabon was a Greek historian, geographer and philosopher.-Life:Strabo was born to an affluent family from Amaseia in Pontus , a city which he said was situated the approximate equivalent of 75 km from the Black Sea...

writing ca 25 BC in his Geographica

Géographica

Géographica is the French-language magazine of the Royal Canadian Geographical Society , published under the Society's French name, the Société géographique royale du Canada . Introduced in 1997, Géographica is not a stand-alone publication, but is published as an irregular supplement to La...

, Book IV, Chapter 6, to gold extraction in the Val d'Aosta in the Alps

Alps

The Alps is one of the great mountain range systems of Europe, stretching from Austria and Slovenia in the east through Italy, Switzerland, Liechtenstein and Germany to France in the west....

. 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 country of the Salassi has gold mines also, which in former times, when the Salassi were powerful, they kept possession of, just as they were also masters of the passes. The Durias River was of the greatest aid to them in their mining — I mean in washing the gold; and therefore, in making the water branch off to numerous places, they used to empty the common bed completely. But although this was helpful to the Salassi in their hunt for the gold, it distressed the people who farmed the plains below them, because their country was deprived of irrigation; for, since its bed was on favourable ground higher up, the river could give the country water. And for this reason both tribes were continually at war with each other. But after the Romans got the mastery, the Salassi were thrown out of their gold-works and country too; however, since they still held possession of the mountains, they sold water to the publicans who had contracted to work the gold mines; but on account of the greediness of the publicans. Salassi were always in disagreement with them too.

The historian Polybius

Polybius

Polybius , Greek ) was a Greek historian of the Hellenistic Period noted for his work, The Histories, which covered the period of 220–146 BC in detail. The work describes in part the rise of the Roman Republic and its gradual domination over Greece...

, who lived from 220 to 170 BC was writing much earlier in The Histories (Book 34), and he records that gold mining

Gold mining

Gold mining is the removal of gold from the ground. There are several techniques and processes by which gold may be extracted from the earth.-History:...

in the Alpine

Alps

The Alps is one of the great mountain range systems of Europe, stretching from Austria and Slovenia in the east through Italy, Switzerland, Liechtenstein and Germany to France in the west....

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

Italy , officially the Italian Republic languages]] under the European Charter for Regional or Minority Languages. In each of these, Italy's official name is as follows:;;;;;;;;), is a unitary parliamentary republic in South-Central Europe. To the north it borders France, Switzerland, Austria and...

. 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 Georg Agricola

Georg Agricola

Georgius Agricola was a German scholar and scientist. Known as "the father of mineralogy", he was born at Glauchau in Saxony. His real name was Georg Pawer; Agricola is the Latinised version of his name, Pawer meaning "farmer"...

, writing in the 15th century in his De Re Metallica

De re metallica

De re metallica is a book cataloguing the state of the art of mining, refining, and smelting metals, published in 1556. The author was Georg Bauer, whose pen name was the Latinized Georgius Agricola...

, does not mention hushing at all. On the other hand, he does describe the many uses of water power, especially for washing ore and driving watermills.

However, the technique was used on a large scale in the lead

Lead

Lead is a main-group element in the carbon group with the symbol Pb and atomic number 82. Lead is a soft, malleable poor metal. It is also counted as one of the heavy metals. Metallic lead has a bluish-white color after being freshly cut, but it soon tarnishes to a dull grayish color when exposed...

mines of northern Britain from at least Elizabethan times onwards. The method is described in the Royal Commission

Royal Commission

In Commonwealth realms and other monarchies a Royal Commission is a major ad-hoc formal public inquiry into a defined issue. They have been held in various countries such as the United Kingdom, Australia, Canada, New Zealand, and Saudi Arabia...

on Children in Mines in 1842 in relation to children being used in the lead

Lead

mines of the Pennines

Pennines

The Pennines are a low-rising mountain range, separating the North West of England from Yorkshire and the North East.Often described as the "backbone of England", they form a more-or-less continuous range stretching from the Peak District in Derbyshire, around the northern and eastern edges of...

. The method was described in some detail by Westgarth Forster

Westgarth Forster

Westgarth Forster was a geologist, mineralogist, and mining engineer. He was the son of a mining engineer, and was born in Garrigill, Cumbria...

in his book A Treatise on a Section of the Strata from Newcastle-upon-Tyne to the Mountain of Cross Fell in Cumberland. The first edition was published in (1809), but the third edition published in 1883 is more widely available. The remnants of the "hush gullies" are visible at many places in the Pennines as well as at many other locations such as the extensive lead mines at Cwmystwyth

Cwmystwyth

Cwmystwyth is a village located in Ceredigion, Wales near Devil's Bridge, and Pont-rhyd-y-groes.The Ordnance Survey calculates Cwmystwyth to be the Centre point of Wales, - History :See Cwmystwyth Mines...

in Ceredigion

Ceredigion

Ceredigion is a county and former kingdom in mid-west Wales. As Cardiganshire , it was created in 1282, and was reconstituted as a county under that name in 1996, reverting to Ceredigion a day later...

, and at the Stiperstones

Stiperstones

The Stiperstones is a very distinctive hill in the county of Shropshire, England. It is a quartzite ridge formed some 480 Million years ago. During the last Ice Age the summit stood out above the glaciers and was subject to constant freezing and thawing which shattered the quartzite into a mass of...

in Shropshire

Shropshire

Shropshire is a county in the West Midlands region of England. For Eurostat purposes, the county is a NUTS 3 region and is one of four counties or unitary districts that comprise the "Shropshire and Staffordshire" NUTS 2 region. It borders Wales to the west...

. The dams used to store the water before use are also often visible at the head of the stream. One famous and spectacular example is the Great Dun Fell

Great Dun Fell

Great Dun Fell is the second-highest hill in the Pennine range, United Kingdom, lying two miles south along the watershed from Cross Fell, its higher neighbour...

hush gully near Cross Fell

Cross Fell

Cross Fell is the highest point in the Pennine Hills of northern England and the highest point in England outside of the Lake District.The summit, at , is a stony plateau, part of a long ridge running North West to South East, which also incorporates Little Dun Fell at and Great Dun Fell at...

, Cumbria

Cumbria

Cumbria , is a non-metropolitan county in North West England. The county and Cumbria County Council, its local authority, came into existence in 1974 after the passage of the Local Government Act 1972. Cumbria's largest settlement and county town is Carlisle. It consists of six districts, and in...

, probably formed in Georgian era

Georgian era

The Georgian era is a period of British history which takes its name from, and is normally defined as spanning the reigns of, the first four Hanoverian kings of Great Britain : George I, George II, George III and George IV...

in the search for lead

Lead

and silver

Silver

Silver is a metallic chemical element with the chemical symbol Ag and atomic number 47. A soft, white, lustrous transition metal, it has the highest electrical conductivity of any element and the highest thermal conductivity of any metal...

. The gully

Gully

A gully is a landform created by running water, eroding sharply into soil, typically on a hillside. Gullies resemble large ditches or small valleys, but are metres to tens of metres in depth and width...

is about 100 feet deep, carries a small stream, and is a prominent landmark

Landmark

This is a list of landmarks around the world.Landmarks may be split into two categories - natural phenomena and man-made features, like buildings, bridges, statues, public squares and so forth...

on the bleak moors. Although the Cornish did not use the term "hushing", there is at least one reference to the technique being used at Tregardock

Tregardock

Tregardock is a coastal settlement and beach in north Cornwall, United Kingdom. It is situated between Trebarwith Strand and Port GaverneTregardock was the location of a World War II aerial bombing and gunnery range at Treligga aerodrome....

in North Cornwall

North Cornwall

North Cornwall was the largest of the six local government districts of Cornwall, United Kingdom. Its council was based in Wadebridge . Other towns in the district included Bude, Bodmin, Launceston, Padstow, and Camelford....

. Around 1580 mine adventurers used the method to work a lead-silver deposit, although lives were lost in the attempt.

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 (Bennett W 1948 A History of Burnley Vol.2 p. 97) notes leases of land for this purpose in the 17th and 18th centuries 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.

External links

The source of this article is wikipedia, the free encyclopedia. The text of this article is licensed under the GFDL.

History

Method

Earlier evidence

Later examples

See also

External links