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Confederate Gulch is a steeply incised valley on the west facing slopes of the Big Belt Mountains. Its small stream drains westward into Canyon Ferry Lake, on the upper Missouri River Valley near present day Townsend, Montana. In 1864 Confederate soldiers on parole from the American Civil War made a minor gold discovery in the gulch, but in 1865 the discovery of the sensationally rich Montana Bar—one of the richest placer strikes per acre ever made—led to other rich gold strikes up and down the gulch, and touched off a frantic boom period of placer gold mining that extended through 1869. From 1866 to 1869 the gulch equaled or outstripped all other Montana Territory mining camps in gold production, producing an estimated $19 to $30 million in gold—late 1860s money. For a time, the gulch became the largest community in Montana—in 1866 Montana had a total population of 28,000, and of these, about 10,000 (35%) were working in Confederate Gulch. The main community was Diamond City , and while gold production was at its height, Diamond City roared along both night and day. During its heyday, Diamond City was the county seat of Montana's Meagher County, although today the area has become part of Broadwater County. In their frantic efforts to get at more gold, the miners built ditches and flumes that extended for miles, and employed high pressure hydraulic mining methods which washed down whole hillsides and ate up the gulch floor. The hydraulic mining process stripped the gulch and left huge spoil banks—hydraulic mining even consumed the site of Diamond City, which had to be moved to a new location. Then the gold ran out, the boom was over and the population simply picked up and left. In 1870 there were only 255 people left and a year later only about 60. Today hardly a trace remains of Diamond City or the other gulch communities. The gulch is quiet and empty, with only an occasional summer prospector, or a rare traveler using the unimproved road that still winds up the gulch from the Missouri Valley and crosses the top of the Big Belts on its way down to the Smith River Valley. Diamond City, Confederate Gulch and the Montana Bar were spectacular examples of the flash-in-the pan Montana placer gold mining camps, but what a flash. ==Geology== Confederate Gulch is considered a separate mining district. The district includes the length of the gulch, along with the upper tributaries of Boulder Creek, Montana Gulch, and Cement Gulch.".〔Lyden, Charles J., 1948 The Gold Placers of Montana. Memoir No. 26. Montana Bureau of Mines and Geology, Butte, Montana, cited in Montana Department of Environmental Quality Report on Confederate Gulch Mining District ()〕 The principal rocks underlying the placer gold deposits of the Confederate Gulch district are the shales of the Spokane and Greyson formations, as well as limestones of the Newland formation. These are cut by diorite and quartz diorite dikes, stocks, and sills. Narrow quartz veins, found along fractures in the diorite and along bedding planes in the shale, contain most of the high grade gold ore. Ore values decrease with depth, and few mines have been developed deeper than 150 feet. In addition to the quartz veins in the shales, the diorite contains "low grade mineralized shear zones".〔Sahinen, Uuno Mathias, 1935 Mining Districts of Montana. Unpublished Master's thesis, Department of Geology, Montana School of Mines, Butte; Pardee, Joseph Thomas and F. C. Schrader, 1933 "Metalliferous Deposits of the Greater Helena Mining Region, Montana", U. S. Geological Survey Bulletin #842, reprint of article in Mining Truth, Vol. 14, No. 10; Reed, Glenn C., 1951 Mines and Mineral Deposits (Except Fuels), Broadwater County, Mont. Information Circular 7592. United States Department of the Interior, Bureau of Mines), cited by Montana Department of Environmental Quality Report on Confederate Gulch ().〕 These Spokane, Greyson and Newland formations have been uniformly considered to be in the Middle Proterozoic Belt Supergroup. In this classification these formations would be much older than the overlying Flathead sandstone from the Middle Cambrian Period, and the division between the older Proterozoic rocks, and the newer Cambrian rocks was considered to be a significant disconformity. New field work in the Big Belt Mountains, suggests that some rocks mapped as the Spokane Formation are conformable with overlying Middle Cambrian strata, and are not part of the Middle Proterozoic Belt Supergroup, but are part of strata that may be younger Late Neoproterozoic.〔DETRITAL ZIRCON EVIDENCE REQUIRES REVISION OF BELT STRATIGRAPHY IN SOUTHWESTERN MONTANA, BALGORD, Elizabeth, MAHONEY, J. Brian, Department of Geology, GINGRAS, Murray K., 2009 Portland GSA Annual Meeting (18–21 October 2009), Paper No. 232-1〕 The rich placer gravels of the drainages were deposited during the interglacial stages of the Pleistocene epoch.〔Montana Department of Environmental Quality Report on Confederate Gulch Mining District () citing Pardee, Joseph Thomas and F. C. Schrader, 1933 "Metalliferous Deposits of the Greater Helena Mining Region, Montana", U. S. Geological Survey Bulletin #842, reprint of article in Mining Truth, Vol. 14, No. 10, and Reed, Glenn C. 1951 Mines and Mineral Deposits (Except Fuels), Broadwater County, Mont. Information Circular 7592. United States Department of the Interior, Bureau of Mines.〕 Confirmation of concentration of the placer gold deposits in relatively recent times is indicated by the bones of mastodons and elephants that were dug out of the gravels.〔 The distribution of the placer gold concentrations suggests that the common source of most of the placer gold in Confederate Gulch and White Creek was a series of quartz lodes on Miller Mountain on the divide between the two drainages.〔 These gold bearing quartz lodes were consumed by the erosion that produced the placer gold deposits in Confederate and White Gulch. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Confederate Gulch and Diamond City」の詳細全文を読む スポンサード リンク
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