Swanberg Dredge, Rocker Gulch

Swanberg Dredge, Rocker Gulch

by | Jun 23, 2022

Swanberg Dredge is a placer mining machine that extracts gold from sand and gravel and is located in a small artificial pond at Rocker Gulch, about 200 feet (61 m) north of the Nome-Council Highway on the Seward Peninsula, about 18 miles (29 km) west of Safety and 1 mile (1.6 km) east of Nome, Alaska. The dredge is named after Nelson Swanberg Jr. who was part owner of the Rocker Gulch claims before 1940 and owner of the dredge in 1966. Rocker Gulch is an alluvium-filled depression landward of the Bering Sea that was named for a rocker sluice box, a placer mining implement used for separating gold from alluvial sand and gravel. Placer gold has been the principal metallic mineral extracted from the Nome mining district, and from 1898 to 1993, an estimated 4.8 million ounces (150 metric tonnes) of gold have been extracted from beach deposits, and the remainder from streams, colluvial hillslopes, and glacial deposits. About 70 percent was removed from placer deposits that are concentrated along modern and ancestral beaches on the coastal plain and in the shallow nearshore, particularly near modern and ancestral stream channels draining Anvil Mountain and in tributaries of the Nome, Osborn, and Snake rivers. Most of the area is covered by till or drift laid down during a series of Pleistocene glaciations. The most extensive surface drift was deposited during the Nome River glaciation of the Middle Pleistocene age. Ice of this advance flowed southward out of cirques in the Kigluaik Mountains and coalesced with local ice from cirques and small ice caps in the uplands north of Nome. Ice of the Nome River glaciation filled the major trunk streams near Nome and extended southward for several miles into present-day Norton Sound. The subsequent glacier advances extended only as far as 6 miles (10 km) from the Kigluaik Mountains. During and after these ice expansions, fluvial, colluvial, and marine processes modified the landscape and formed gravel-rich alluvial valley fills, and beach and terrace sediments.

The western point of the Seward Peninsula is less than 60 miles (100 km) from the Siberian coast. In 1711, Peter I. Popof learned from the Chukchi people that beyond the islands off Siberia lay a great land with broad rivers and inhabited by people. But the first landing was not until 1732 when Ivan Fedorov and Mikhail Gvozdev sailing on Saint Gabriel crossed the Bering Strait and discovered the Diomede Islands and then sailed farther east toward Cape Prince of Wales on the North American mainland. The first survey of the coast was made by Captain James Cook in 1778. During the succeeding century of Russian occupation, the entire coastline was explored. In 1822, the Russian Captain Vasiliy S. Khromchenko, commanding the Golovnin, surveyed Norton Sound and Golovnin Bay. It was not until 1835 that a trading post was established on Saint Michael Island, the first Russian settlement north of the Aleutian Islands. From this point, trade was carried on with the Yup’ik people to the north. The first significant exploration of the interior was made in 1865-66 by a party led by Ottfried von Bendeleben while seeking a route for a telegraph line. Von Bendeleben reputedly found alluvial gold on the Niukluk River north of Golovnin Bay. The peninsula was regarded as a barren waste for many years after the Alaska Purchase in 1867. Whalers would rendezvous at Port Clarence where they anchored in the early summer while waiting for the sea ice to breakup. Occasionally a trader came from posts such as Unalakleet or Saint Michael and bartered with the Natives, but otherwise, conditions were as primitive as during the Russian occupation. Major alluvial placer gold deposits in the Nome mining district were discovered in September and October of 1898 by John Brynteson, Jafet Lindeberg, and Erik O. Lindblom supported by several Yup’ik Eskimos, including Gabriel Adams and Constantine Uparazuck. The men were part of an active Scandinavian community based at Golovin who originally came to the region mainly for the Swedish Covenant Church. Many of the best placers were located in 1898 and a mining district was formed. The next year gold was discovered on the beach at Nome and the U.S. Geological Survey then predicted that buried beach placer deposits would also be found. The placers were first exploited mainly by hydraulic methods, and major ditches were constructed to supply these operations with water. In the 1920s, after the invention of cold-water thawing to melt the permafrost, large dredges were brought into the thaw fields by Wendell P. Hammon, whose interests were later consolidated by the U.S. Smelting, Refining, and Mining Company.

Gold mining languished during World War I, then increased dramatically when President Franklin D. Roosevelt raised the price of gold from $27 to $35 an ounce in 1934, but mining was restricted in 1942 as not essential to the World War II effort. After the war, the Gold Beach Dredging Company acquired claims to Rocker Gulch and hoped to resume gold dredging operations. In 1946, the company purchased a small gold dredge in San Francisco and shipped it in pieces to Nome where it was reassembled by Walter Johnson. The dredge only operated for one season before a local bank owned by Grant Jackson took possession of the dredge. The Gold Beach Dredging Company hoped to get it back and in 1948 acquired rights to dig a ditch from the Nome River to Rocker Gulch but the ditch was never constructed. The dredge remained an asset of the bank until the Alaska National Bank of Fairbanks bought out the Nome bank in 1963. Alaska National Bank sold the dredge for an undisclosed sum to bank board member Nelson Swanberg Jr. in 1966, the same person that originally owned the Rocker Gulch claims before 1940. Swanberg used the dredge as a tourist attraction, and today the City of Nome owns the dredge as part of the Gold Rush Park. The dredge remains where it stopped operating and is an example of a small remote mining operation, the economic risks of gold mining, and the challenges miners faced working in the far north during the middle years of the twentieth century. The Swanberg Dredge has a barge-like steel hull, 60 feet (18 m) long, 30 feet (9 m) wide, and about 6 feet (1.8 m) deep. There is a coal-fired boiler in the hull that provided steam heat and a diesel generator that provided electrical power for the machinery. A one-story superstructure covers virtually the entire hull area. A second story on the half of the superstructure toward the bow of the dredge contains the winch room, hopper, and upper end of the trommel screen. The superstructure is steel with corrugated metal sheathing. The flat roofs are covered with metal sheets.  Read more here and here. Explore more of Rocker Gulch here:

About the background graphic

This ‘warming stripe’ graphic is a visual representation of the change in global temperature from 1850 (top) to 2021 (bottom). Each stripe represents the average global temperature for one year. The average temperature from 1971-2000 is set as the boundary between blue and red. The color scale goes from -0.7°C to +0.7°C. The data are from the UK Met Office HadCRUT4.6 dataset. 

Credit: Professor Ed Hawkins (University of Reading). Click here for more information about the #warmingstripes.

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