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File:Section of a drift mine in frozen gravel.jpg

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English: Diagram illustrating drift mining in permafrost as practiced in Alaska and Yukon in the early 20th century. The deposit is usually an old stream bed overlain by gravel. The greatest concentration of gold is near the bedrock. The gravel is thawed with steam points driven into the mass. The thawed mass is dug out, keeping the gold-bearing material separate from the overburden The gold-bearing material is sent for washing while the overburden accumulates as a pile in the tunnel.
Date copyright 1909
Source Through the Yukon and Alaska [1] Mining and Scientific Press, San Francisco, 1909 p215.
Author T.A. Rickard
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current18:51, 4 December 2010Thumbnail for version as of 18:51, 4 December 20101,482 × 743 (113 KB)Dankarl (talk | contribs){{Information |Description={{en|1=Diagram illustrating drift mining in permafrost as practiced in Alaska and Yukon in the early 20th century. The deposit is usually an old stream bed overlain by gravel. The greatest concentration of gold is near the bedr

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