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43-566: The river provides the principal drainage for an area of the remote Alaska Interior on the north and west side of the Alaska Range , flowing southwest into Kuskokwim Bay on the Bering Sea . The highest point in its watershed is Mount Russell . Except for its headwaters in the mountains, the river is broad and flat for its entire course, making it a useful transportation route for many types of watercraft, as well as road vehicles during

86-529: A Roman alluvial gold mine at Las Médulas , Spain are so spectacular as to justify the site being designated UNESCO World Heritage status. The methods used by the Roman miners are described by Pliny the Elder in his work Naturalis Historia published in about 77 AD. The author was a Procurator in the region and so probably witnessed large-scale hydraulic mining of the placer deposits there. He also added that

129-416: A few feet, or more than ten feet (a common term for one that is over six feet +/- is a "Long Tom"). While they are capable of handling a larger volume of material than simpler methods such as the rocker box or gold panning, this can come at the cost of efficiency, since conventional sluice boxes have been found to recover only about 40% of the gold that they process. The sluice box was used extensively during

172-407: A larger volume became more common. The same principle may be employed on a larger scale by constructing a short sluice box , with barriers along the bottom called riffles to trap the heavier gold particles as water washes them and the other material along the box. This method better suits excavation with shovels or similar implements to feed ore into the device. Sluice boxes can be as short as

215-546: A new record with over 6,600,000 acres (27,000 km ) burned. The average annual precipitation in Fairbanks is 11.3 inches (287 mm). Most of this comes in the form of snow during the winter. Most storms in the interior of Alaska originate in the Gulf of Alaska , south of the state, though these storms often have limited precipitation due to a rain shadow effect caused by the Alaska Range . On clear winter nights,

258-481: A sluice box, being fed not by a sluice but by hand. The box sits on rockers, which when rocked separates out the gold, and the practice was referred to as "rocking the golden baby". A typical rocker box is approximately 42 inches long, 16 inches wide and 12 inches deep with a removable tray towards the top, where gold is captured. The rocker was commonly used throughout North America during the early gold rush, but its popularity diminished as other methods that could handle

301-443: A stream bed. Gold accumulations in an old stream bed that are high are called bench deposits. They can be found on higher slopes that drain into valleys. Dry stream beds (benches) can be situated far from other water sources and can sometimes be found on mountaintops. Today, many miners focus their activities on bench deposits. Deep leads are created when a former stream bed is covered over by later sediments or by igneous rock from

344-423: A trough into the primary sluice box where it is filtered again. Both the grizzly and undercurrent are designed to increase efficiency, and were often used in combination. Sluicing is only effective in areas where there is a sufficient water supply, and is impractical in arid areas. Alternative methods developed that used the blowing of air to separate out gold from sand. One of the more common methods of dry washing

387-799: A vein, are typically only a minuscule portion of the total deposit. Since gems and heavy metals like gold are considerably denser than sand , they tend to accumulate at the base of placer deposits. Placer deposits can be as young as a few years old, such as the Canadian Queen Charlotte beach gold placer deposits, or billions of years old like the Elliot Lake uranium paleoplacer within the Huronian Supergroup in Canada. The containing material in an alluvial placer mine may be too loose to safely mine by tunnelling, though it

430-495: A volcanic eruption. Examples existed in the goldfields of Gulgong and Creswick in Australia. The gold bearing gravel is accessed by shafts and drives similar to underground mining techniques but is typically processed as if alluvial gold. The heat associated with an igneous lava flow, in some cases, altered the gold bearing gravel so that it needed to be crushed first to extract the gold; an example of this kind of deep lead

473-460: Is " winnowing ". This method was most commonly used by Spanish miners in America, and only requires a blanket and a box with a screen on the bottom. The material is first filtered through the box so only the finer material is placed onto the blanket. The material on the blanket is then flung into the air so that any breeze can blow away the lighter material and leave the gold behind. While this method

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516-413: Is extremely simple and requires very few materials, it is also slow and inefficient. A trommel is composed of a slightly inclined rotating metal tube (the 'scrubber section') with a screen at its discharge end. Lifter bars, sometimes in the form of bolted in angle iron, are attached to the interior of the scrubber section. The ore is fed into the elevated end of the trommel. Water, often under pressure,

559-614: Is largely underlined by discontinuous permafrost , which grades to continuous permafrost as the Arctic Circle is approached. While the vast majority of indigenous Native people of Interior Alaska are Athabaskan , large Yup'ik and Iñupiaq populations reside in Fairbanks . The federally recognized tribes of Interior Alaska: 65°N 152°W  /  65°N 152°W  / 65; -152 Placer mining Placer mining ( / ˈ p l æ s ər / )

602-777: Is located within the Yukon Delta National Wildlife Refuge . The river receives the Big River from the south approximately 20 miles (32 km) southwest of Medfra. It receives the Swift , Stony , and Holitna rivers from the south at the southern end of the Kuskokwim Mountains before emerging on the coastal plain. It receives the Aniak River from the south at Aniak. Approximately 20 miles (32 km) upstream from Bethel it receives

645-446: Is now rarely used for profit since even an expert gold prospector can only process approximately one cubic yard of material for every 10 hours of work. A rocker box (or "cradle") is capable of greater volume than a gold pan; however, its production is still limited when compared to other methods of placer mining. It is only capable of processing about 3 or 4 yards of gravel a day. It is more portable and requires less infrastructure than

688-466: Is possible where the ground is permanently frozen . Where water under pressure is available, it may be used to mine, move, and separate the precious material from the deposit, a method known as hydraulic mining , hydraulic sluicing or hydraulicking . The word placer derives from the Spanish placer , meaning shoal or alluvial/sand deposit, from plassa (place) from Medieval Latin placea (place)

731-624: Is provided to the scrubber and screen sections and the combination of water and mechanical action frees the valuable heavy minerals from the lighter gravel. The mineral bearing ore that passes through the screen is then further concentrated in smaller devices such as sluices and jigs. The larger pieces of ore that do not pass through the screen can be carried to a waste stack by a conveyor. Large-scale sifting of placer gold from large volumes of alluvial deposits can be done by use of mechanical dredges. These dredges were originally very large boats capable of processing massive amounts of material; however, as

774-495: Is the Mexican dry wash. This method involves placing gravel on a riffle board with a bellows placed underneath it. The bellows is then used to blow air through the board in order to remove the lighter material from the heavier gold. The amount of gravel that can be processed using the Mexican dry wash technique varies from 1 1/2 to 4 cubic yards per day, and can be processed at a maximum efficiency of 80%. Another form of dry washing

817-502: Is the mining of stream bed deposits for minerals . This may be done by open-pit mining or by various surface excavating equipment or tunneling equipment. Placer mining is frequently used for precious metal deposits (particularly gold ) and gemstones , both of which are often found in alluvial deposits—deposits of sand and gravel in modern or ancient stream beds , or occasionally glacial deposits. The metal or gemstones, having been moved by stream flow from an original source such as

860-1182: The Alaska Range to the south and the Brooks Range to the north. It is largely wilderness . Mountains include Denali in the Alaska Range , the Wrangell Mountains , and the Ray Mountains . The native people of the interior are Alaskan Athabaskans . The largest city in the interior is Fairbanks , Alaska 's second-largest city, in the Tanana Valley . Other towns include North Pole , just southeast of Fairbanks, Eagle , Tok , Glennallen , Delta Junction , Nenana , Anderson , Healy and Cantwell . The interior region has an estimated population of 113,154. Interior Alaska experiences extreme seasonal temperature variability. Winter temperatures in Fairbanks average −12 ° F (−24 ° C ) and summer temperatures average +62 °F (+17 °C). Temperatures there have been recorded as low as −65 °F (−54 °C) in mid-winter, and as high as +99 °F (+37 °C) in summer. Both

903-546: The Bering Sea . The Kuskokwim is fed by several forks in central and south-central Alaska. The North Fork (250 mi/400 km) rises in the Kuskokwim Mountains approximately 200 miles (320 km) WSW of Fairbanks and flows southwest in a broad valley. The South Fork (200 mi/320 km) rises in the southwestern end of the Alaska Range west of Mount Gerdine and flows north-northwest through

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946-485: The California gold rush for larger scale operations. When streams became increasingly depleted, the grizzly and undercurrent variants of the sluice box were developed. The grizzly is a set of parallel bars placed at a 45-degree angle over the main sluice box, which filter out larger material. The undercurrent variety includes additional, auxiliary sluice boxes where material is initially filtered. It then travels through

989-593: The Kisaralik and Kwethluk rivers from the south. It receives the Eek River from the east at Eek near its mouth on Kuskokwim Bay. The principal economic activities along the river have historically been fur trapping and fishing. Subsistence fishing for salmon and whitefish provides a staple of the Yup'ik diet along the river. Economic deposits of placer gold were discovered in 1901 near Aniak. Mineral production in

1032-515: The Yukon River , surrounded by large spruce forests. It passes a series of Yup'ik villages, including Aniak , and approaches within 50 mi (80 km) of the Yukon before diverging southwest. Southwest of Bethel , the largest community on the river, it broadens into a wide marshy delta that enters Kuskokwim Bay approximately 50 mi (80 km) SSW of Bethel. The lower river below Aniak

1075-450: The aurora borealis can often be seen in the sky. Like all subarctic regions, the months from May to July in the summer have no night, only a twilight during the night hours. The months of November to January have little daylight. Fairbanks receives an average 21 hours of daylight between May 10 and August 2 each summer, and an average of less than four hours of daylight between November 18 and January 24 each winter. The interior of Alaska

1118-638: The North Fork, Lake Minchumina . The river's name comes from the Yup'ik , kusquqviim , recorded by a Russian sailor in 1826. The Tanana (Athabaskan) name for the river was Chin-ana . Upper Kuskokwim (Kolchan) is often used to mean the people of the upper parts of the river, while Yup'ik people live along the lower river. The river is formed by the confluence of East Fork Kuskokwim River and North Fork Kuskokwim River, 5 miles (8 km) east of Medfra . From there it flows southwest to Kuskokwim Bay and

1161-410: The Yukon, placer deposits may be mined underground. As the frozen ground is otherwise too hard and firm to mine by hand, historically fires were built so as to thaw the ground before digging it. Later methods involve blasting jets of steam ("points") into the frozen deposits. Deep leads are accessed by techniques similar to conventional underground mining. Although this procedure is not required,

1204-564: The flow of water is a great location to find gold. Gold is very dense and is often found in a stream bed. Many different gold deposits are dealt with in different ways. Placer deposits attract many prospectors because their costs are very low. There are many different places gold could be placed, such as a residual, alluvial, and a bench deposit. Residual deposits are more common where there has been weathering on rocks and where there hasn't been water. They are deposits which have not been washed away yet or been moved. The residual usually lies at

1247-565: The gold fields, material that was carried downstream and raised the level of portions of the Central Valley by some seven feet in affected areas and settled in long bars up to 20 feet thick in parts of San Francisco Bay . The process raised an opposition calling themselves the "Anti-Debris Association". In January 1884, the North Bloomfield Mining and Gravel Company case banned the flushing of debris into streams, and

1290-492: The gold for a large part of the ancient world. Hydraulic mining methods such as hushing were used widely by the Romans across their empire, but especially in the gold fields of northern Spain after its conquest by Augustus in 25 BC. One of the largest sites was at Las Médulas , where seven 30 mile long aqueducts were used to work the alluvial gold deposits through the first century AD. In North America , placer mining

1333-481: The gold has become increasingly depleted in the most easily accessible areas, smaller and more maneuverable dredges have become much more common. These smaller dredges commonly operate by sucking water and gravel up through long hoses using a pump, where the gold can then be separated using more traditional methods such as a sluice box. In areas where the ground is permanently frozen , such as in Siberia, Alaska, and

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1376-833: The highest and lowest temperature records for the state were set in the Interior, with 100 °F (38 °C) in Fort Yukon and −80 °F (−62 °C) in Prospect Creek . Temperatures within a given winter are highly variable as well; extended cold snaps of forty below zero can be followed by unseasonable warmth with temperatures above freezing due to chinook wind effects. Summers can be warm and dry for extended periods creating ideal fire weather conditions. Weak thunderstorms produce mostly dry lightning, sparking wildfires that are mostly left to burn themselves out as they are often far from populated areas. The 2004 season set

1419-545: The local lake Carucedo had been heavily silted by the mining methods. Environmental activists describe the hydraulic mining form of placer mining as environmentally destructive because of the large amounts of silt that it adds to previously clear running streams (also known as the "Dahlonega Method"). Most placer mines today use settling ponds , if only to ensure that they have sufficient water to run their sluicing operations. In California, from 1853 to 1884, "hydraulicking" of placers removed an enormous amount of material from

1462-462: The minerals from the ground, and separating it from the non-gold or non-gems. The simplest technique to extract gold from placer ore is panning . This technique has been dated back to at least the Roman Empire. In panning, some mined ore is placed in a large metal or plastic pan, combined with a generous amount of water , and agitated so that the gold particles, being of higher density than

1505-497: The mountains, past Nikolai , receiving other streams that descend from the Alaska Range northwest of Denali . The two forks join near Medfra, and from there the main stem of the Kuskokwim flows southwest, past McGrath , in a remote valley between the Kuskokwim Mountains to the north and the Alaska Range to the south. In southwest Alaska the river emerges from the Kuskokwim Mountains in a vast lake-studded alluvial plain south of

1548-511: The origin word for "place" and "plaza" in English. The word in Spanish is thus derived from placea and refers directly to an alluvial or glacial deposit of sand or gravel. An alternative etymology derives the English word from American Spanish placer (placer, sandbank), from earlier placel , apparently from obsolete Portuguese placel (placer, sandbank). Placers supplied most of

1591-430: The other material, settle to the bottom of the pan. The lighter gangue material such as sand, mud and gravel are then washed over the side of the pan, leaving the gold behind. Once a placer deposit is located by gold panning, the miner usually shifts to equipment that can treat volumes of sand and gravel more quickly and efficiently. Gold panning was commonly used on its own during the California gold rush ; however, it

1634-403: The process water may be continuously recycled and the ore from which the sought-after minerals have been extracted ("the tailings") can be reclaimed. While these recycling and reclamation processes are more common in modern placer mining operations they are still not universally done. In earlier times the process water was not generally recycled and the spent ore was not reclaimed. The remains of

1677-557: The region has mainly been from scattered placer gold deposits that through 2004 had produced a total of 3.5 million troy ounces of gold. The primary route of the Iditarod Trail follows the South Fork Kuskokwim River out of the Alaska Range and crosses the main stem of the river near McGrath. Alaska Interior Interior Alaska is the central region of Alaska 's territory, roughly bounded by

1720-453: The site of the lode. This type of deposit undergoes rock weathering. Alluvial or eluvial deposits are the most common type of placer gold, and are often the richest. They contain pieces of gold that have been washed away from the lode by the force of water, and have been deposited in sediment in or near watercourses or former watercourses. Therefore, they are mostly found in valleys or flood plains. Bench deposits are created when gold reaches

1763-482: The winter when it is frozen over . It is the longest free flowing river in the United States. Kuskokwim is a loose transliteration of a Yupʼik word. It is a compound word meaning big slow moving thing. The Alaska Natives of Kuskokwim are Yupʼik Eskimo on the lower Kuskokwim, Deg Xitʼan Athabaskan on the middle Kuskokwim, Upper Kuskokwim Athabaskan on the upper Kuskokwim, and Koyukon Athabaskan on

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1806-814: Was famous in the context of several gold rushes , particularly the California Gold Rush and the Colorado Gold Rush , the Fraser Canyon Gold Rush and the Klondike Gold Rush . Placer mining continues in many areas of the world as a source of diamonds, industrial minerals and metals, gems (in Myanmar and Sri Lanka ), platinum, and of gold (in Yukon , Alaska and British Columbia ). An area well protected from

1849-416: Was found at Forest Reefs , also in Australia. If vegetation was buried along with the old stream, by a volcanic eruption, the effect of heat and decay upon that buried vegetation can result in the presence of harmful amounts of carbonic acid gas ( H 2 C O 3 ), as occurred in the deep lead deposit at Creswick. A number of methods are used to mine placer gold and gems, both in terms of extracting

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