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RT @USGS: [PUB] – ‘Classic’ USGS pub - The mining districts of the Western United States Bulletin 507 By: James M. Hill and Waldemar Lindgr…
RT @USGS: [PUB] – ‘Classic’ USGS pub - The mining districts of the Western United States Bulletin 507 By: James M. Hill and Waldemar Lindgr…
one of those maps that ends up Explaining A Lot™ in hindsight
[PUB] – ‘Classic’ USGS pub - The mining districts of the Western United States Bulletin 507 By: James M. Hill and Waldemar Lindgren (1912) https://t.co/fQU3Qe3HhE #geology #mining https://t.co/ZviHsOAVkt