Island Mountain: Difference between revisions
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[[Category:Trinity County, California]] |
[[Category:Trinity County, California]] |
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[[Category:Mountains of California]] |
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Revision as of 04:16, 10 April 2010
| Island Mountain | |
|---|---|
 | |
| Highest point | |
| Elevation | 3,839 ft (1,170 m) |
| Coordinates | 39°58′N 123°30′W / 39.967°N 123.500°W |
| Geography | |
| Location | Trinity County, California |
| Topo map(s) | USGS Bell Springs and Updegraff Ridge |
Island Mountain is a resistant formation of volcanic and metavolcanic rock in the Franciscan Assemblage of southwestern Trinity County. The Eel River makes an abrupt "S" curve around the mountain in its otherwise north-northwesterly flow between the California Coast Ranges.[1]
History
Island Mountain was the final obstacle to completion of the Northwestern Pacific Railroad between San Francisco and Eureka, California. Railroad construction proceeded northerly down the west side of the Eel River canyon and bridged the river at the "S" curve to enter 4313-foot (1.3-km) tunnel number 27 through the mountain.[2] There was a golden spike ceremony downstream of the mountain at Cain Rock in 1914 to complete the railroad.[3] The redwood framing of tunnel 27 burned on 6 September 1978, and a significant length of the tunnel collapsed. Tunnel rebuilding costing 3.8 million dollars was completed on 7 December 1979.[4]
Mining
A volcanogenic massive sulfide ore deposit within the mountain was mined after rail service became available. Mining recovered 4100 tons of copper, 140,000 ounces of silver, and 8,600 ounces of gold between 1915 and 1930.[5] Minerals identified within the ore body include chalcanthite, chalcopyrite, copiapite, goslarite, pyrite, and pyrrhotite.[6] Volcanic rock was quarried from Island Mountain by Northwestern Pacific Railroad for heavy riprap used as far away as Humboldt Bay.[2]
References
- ^ Strand, Rudolph G. Geologic Map of California:Redding Sheet (1962) State of California Resources Agency
- ^ a b Gale, V.J. and Valles, R.C.(Roadmasters) (1978). (untitled maintenance-of-way charts). Southern Pacific Railroad.
{{cite book}}: CS1 maint: multiple names: authors list (link) - ^ Stindt, Fred A. (1964). The Northwestern Pacific Railroad. Fred A. Stindt. p. 50.
- ^ Stindt, Fred A. (1985). The Northwestern Pacific Railroad, Volume Two. Fred A. Stindt. pp. 15–19. ISBN 0-9615465-0-6.
- ^ Fenelon F. Davis (1966) Economic Mineral Deposits in the Coast Ranges, in Geology of Northern California, California Division of Mines and Geology, Bulletin 190, p.320.
- ^ http://www.mindat.org/loc-12058.html