Except for small recoveries of gold by Indians and Spanish explorers, gold was first discovered and mined in the United States in North Carolina in 1799. This initial discovery was followed by others in the 1820's and 1830's in several of the other Appalachian States. These States produced significant amounts of gold until the Civil War. After the discovery of gold in California in 1848, the Western States contributed the bulk of this country's gold production. New discoveries in widely separated areas in the Western States followed in rapid succession.From 1799 through 1965, the United States produced about 307,182,000 ounces of gold, which at the price of $35 per ounce would be valued in round numbers at $10,751 million. In an analysis of gold-production trends, the period 1932-59 is particularly informative; the effect of the increase of the price of gold in 1934 from $20.67 to $35 per ounce is clearly shown, as is the effect of a fixed selling price of gold combined with rising costs of labor and material in post-World War II years.Districts that have produced more than 10,000 ounces are distributed in 31 States. Five States-California, Colorado, South Dakota, Alaska, and Nevada-have yielded more than 75 percent of the gold produced in this country. Of the more than 500 districts that have produced more than 10,000 ounces of gold, 45 have produced more than 1 million ounces, and four-Lead, S.D., Cripple Creek, Colo, Grass Valley, Calif., and Bingham, Utah-have produced more than 10 million ounces each. The 25 leading districts have produced about half the gold mined in the United States, and the 508 districts that are described account for roughly 90 to 95 percent.In general, gold is derived from three types of ore: (1) ore in which gold is the principal metal of value, (2) basemetal ore which yields gold as a byproduct, and (3) placers. In the early years, most of the gold was mined from placers, but after 1873, though placers were by no means depleted and continued to contribute significantly to our annual output, production came chiefly from lode deposits. The search for gold led to the discovery and development of many silver, lead, copper, 11nd zinc deposits from which gold was recovered as a byproduct. Since the late 1930's, byproduct gold has become a significant fraction of the annual domestic gold output.Most of the gold deposits in the United States are closely associated with and probably genetically related to small batholiths, stocks, and satellitic intrusive bodies of quartz monzonitic composition that range in age from Jurassic to Tertiary. Some deposits, as those in the Southeastern States, may be genetically related to granitic bodies that were intruded at the close of Paleozoic time, and some deposits, as at Jerome, Ariz., are Precambrian in age.Alaska, the fourth largest gold-producing State, yielded a 2 PRINCIPAL GOLD-PRODUCING DISTRICTS OF THE UNITED STATES City, Orofino, Boise Basin, Florence, and Warren, and a brief period of feverish activity followed. By 1870, many of the richer place...
This report describes the stratigraphy and structure of an area of about 5,000 square miles in northeastern Wyoming and adjacent parts of Montana and South Dakota. The area includes the northern end and part of the western side of the Black Hills uplift and the adjoining part of the Powder River Basin.About 11,000 feet of sedimentary rocks ranging in age from Mississippian to early Tertiary are exposed in the area, not including surficial deposits of Tertiary(?) and Quaternary age. The oldest rocks crop out in the southeastern part of the area and consist of 500 to 600 feet of light-gray cherty limestone that makes up the Early Mississippian Pahasapa limestone. Unconformably overlying the Pahasapa limestone is the Minnelusa formation of Pennsylvanian and Permian age. It is 650 to 800 feet thick in drill holes and at outcrops in the southeastern part of the •area, and it consists of interbedded lightgray and pink sandstone, gray sandy limestone and dolomite, some red shale and siltstone, and local beds of gypsum and. anhydrite. The Permian Opeche formation overlies the Minnelusa formation unconformably and comprises 60 to 90 feet of red fine-grained sandstone, siltstone, and silty• shale. Next in order is the Permian Minnekahta limestone, which is composed of light-gray and light purplish-gray thin-bedded limestone about 40 feet thick. The Spearfish formation, 450 to 825 feet thick, BLACK HILLS UPLIFT, WYOMING, MONTANA, SOUTH DAKOTA Weston County. It is composed of dark-gray shale, at places sandy and silty, interbedded with bentonite and numerous limestone and siderite concretions. The formation is divided into several members, which from base to top are the Gammon ferruginous member, 0 to about 1,000 feet thick; the Mitten black shale mem~r, 145 to about 870 feet thick; and the upper part of the Pierre shale including the Monument Hill bentonitic member 150 to about 220 feet thick, and the somewhat younger Kara bentonitic member about 100 feet thick. In the northern part of the area, the Gammon ferruginous member contains a zone of sandstone and sandy shale about 100 feet thick known as the Groat sandstone bed.The Fox Hills sandstone overlies the Pierre shale and is 150 to 200 feet thick. .Yellowish-gray sandstone and gray shale make up the Fox Hills sandstone at most places except in Carter County, Mont., where as much as 100 feet of very light gray cliff-forming sandstone crops out at the top of the formation and is mapped separately as the Colgate member .. Nonmarine sedimentary rocks overlie the Fox Hills sandstone and make up an essentially conformable sequence of sandstone, shale, •and coal beds that includes the Lance formation of Late Cretaceous age, the Fort Union formation of Paleocene age, and the W•asatch formation of Eocene age. The Lance formation is 1,600 feet thick in northern Weston County, Wyo., but thins northward to about 500 feet in Carter County, Mont. The overlying Fort Union formation, 1,500 to about 2,100 feet thick, also thins northward. It is divided into the Tullock member at the base...
In pocket 2. Underground geologic maps of the Wilfley and Kimberly, Robinson, and Lucky Strike-Victory mines ____ In pocket 24 24 24 28 31
Purpose and scope____________________ Methods of investigation. ________________ __ Culture....____________________________ -Topography. _____________________________ Drainage. _______________________ _. FIGURE 6. Index map of land-pebble phosphate district, Hardee and De Soto Counties___________________________________ 66 7. Summary of exposed formations in Hardee and De Soto Counties. _____________ __ ________ 70 8. Diagram showing general stratigraphic relations of the formations in Hardee and De Soto Counties _____________ 71 ,. 9. Sketch map and cross sections of borrow pit, 1.6 miles east of
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