View source for Specimen Ridge

{{Short description|Mountain ridge in Wyoming, United States}}
{{Infobox mountain
| name = Specimen Ridge
| photo = SpecimenRidgeLamarValleyYNP.jpg
| photo_caption = North face Specimen Ridge from Lamar Valley
| elevation_ft = 8379
| elevation_ref = <ref name=gnis/>
| prominence = 
| map = 
| map_caption = 
| label_position = 
| listing = 
| location = [[Yellowstone National Park]], [[Park County, Wyoming|Park County]], [[Wyoming|Wyoming, U.S.]]
| range = Washburn Range
| coordinates = {{coord|44|52|13|N|110|17|48|W|display=inline, title|name=Specimen Ridge}}
| coordinates_ref = <ref name=gnis>{{cite gnis |id=1594772 |name=Specimen Ridge |access-date=2009-12-31}}</ref>
| topo = Amethyst Mountain
| type = 
| age = 
| first_ascent = 
| easiest_route = 
}}

'''Specimen Ridge''', el. {{convert|8379|ft|m}} is an approximately  {{convert|8.5|mi|km|adj=on}} ridge along the south rim of the [[Lamar River|Lamar Valley]] in [[Yellowstone National Park]].  The ridge separates the Lamar Valley from Mirror Plateau.  The ridge is oriented northwest to southeast from the Tower Junction area to [[Amethyst Mountain]].  The ridge is known for its abundance of [[amethyst]], [[opal]] and petrified wood.  It was referred to as ''Specimen Mountain'' by local miners and was probably named by prospectors well before 1870.<ref>Whittlesey, Lee (1988) ''Yellowstone Place Names.'' Montana Historical Society Press, Helena, Montana. 145 pp. {{ISBN|0-917298-15-2}}</ref> The south side of the ridge is traversed by the {{convert|18.8|mi|km|adj=on}} Specimen Ridge Trail between Tower Junction and [[Soda Butte Creek]].  The trail passes through the Petrified Forest<ref>Knowlton, F. H. (1914) [https://web.archive.org/web/20070617231207/http://www.nps.gov/history/history/online_books/yell/knowlton/sec1.htm ''The Fossil Forests of Yellowstone National Park.''] National Park Service, Department of the Interior, Office of the Secretary, Wasignton DC. 31 pp. Last accessed September 23, 2013.</ref> and over the summit of Amethyst Mountain el. {{convert|9614|ft|m}}.<ref>Schneider, Bill (2003) ''Hiking Yellowstone National Park.'' Falcon Press, Guilford, Connecticut. 101 pp. {{ISBN|0-7627-2539-7}} (pp. 199–202)</ref>

==Geology==
Specimen Ridge consists of a geological [[Formation (stratigraphy)|formation]] known as the Lamar River Formation. Within the Specimen Mountain area, it consists predominantly of an undetermined thickness of [[Conglomerate (geology)|conglomerate]] that is interbedded with lesser proportions of [[tuff]]aceous [[sandstone]] and [[siltstone]]. [[Volcanic]] [[breccia]] is absent. The conglomerates consist of a mixture of [[mudflow]] deposits ([[lahars]]) that are complexly interlayered with [[Braided river|braided]] and [[meander|meandering stream]] deposits. The lahar (mudflow) deposits consist of normally massive and structureless, matrix-supported conglomerates that contain subangular, poorly sorted gravel that range in size from {{convert|1|cm|in|abbr=on}} to {{convert|2|m|ft|sp=us}} in diameter. The majority of the sediments consist of well-bedded, clast-supported fluvial conglomerates that consist of grain-supported, subrounded, and moderately well-sorted gravel that typically ranges in size from {{convert|1|cm|in|abbr=on}} to {{convert|30|cm|in|abbr=on}}. The vast majority of [[petrified wood]] occurs within the conglomerates. The [[fossil]] leaves, needles, pollen, and cones are largely found within tuffaceous sandstones and siltstones that were deposited either along the banks of either braided or meandering rivers, within their abandoned channels, or in shallow lakes of very limited extent. At Specimen Ridge, these sediments consist of volcanic material eroded from and accumulated downslope of an adjacent Eocene [[stratovolcano]], known the 'Washburn Volcano', in an intermountaine basin. The Lamar River Formation is part of the Washburn Group.<ref name="Fritz1980a">Fritz, WJ (1980a) ''Depositional Environment of the Eocene Lamar River Formation in Yellowstone National Park.'' Doctoral Dissertation, The University of Montana, Missoula, Montana.</ref><ref name="Fritz1980b">Fritz, WJ (1980b) ''Stratigraphic framework of the Lamar River formation in Yellowstone National Park.'' Northwest Geology. vol. 9, pp. 1-18.,</ref><ref name="Fritz1981a">Fritz, WJ (1981) ''Reinterpretation of the depositional environment of the Yellowstone fossil forests: Reply.'' Geology. 9(2):53-54.</ref><ref name="Fritz1982a">Fritz, WJ (1982) ''Geology of the Lamar River Formation, northeast Yellowstone National Park.'' In SG Reid and DJ Foote, eds., pp. 73-101, Geology of Yellowstone Park Area. Wyoming Geological Association Guidebook, 33rd Annual Field Conference, 1982, Wyoming Geological Association, Casper, Wyoming.</ref><ref name="Feeley2002a">Feeley, TC, MA Cosca, MA and CR Lindsay (2002) ''Petrogenesis and implications of calc-alkaline cryptic hybrid magmas from Washburn Volcano, Absaroka Volcanic Province, USA.'' Journal of Petrology. 43(4):663-703.</ref>

The Lamar River Formation is part of the Absaroka Volcanic Supergroup. It is a thick accumulation of volcanic rocks that were either erupted from or eroded from the slopes of two belts of Eocene stratovolcanoes. These rocks accumulated within an intermountain basin between these belts. Before they were destroyed by erosion, these volcanoes are estimated to have had peaks that rose about {{convert|8,000|ft|m|sp=us}} to {{convert|10,000|ft|m|sp=us}} above adjacent intermountain valleys. Depending on location, the Lamar River Formation [[Unconformity|unconformably]] overlies either older [[lava]]s, conglomerates, tuffs, volcanic breccias of the Sepulcher Formation; [[Mississippian age|Mississippian]] [[limestone]]s and [[Dolomite (rock)|dolomite]]s; or [[Precambrian]] [[gneiss]]. Based on radiometric dates and plant fossils from it, the Lamar River Formation is considered to be of Middle Eocene age.<ref name="Fritz1980a"/><ref name="SmedesOthers1972a">Smedes, HW, and HJ Prostka, 1972, [https://pubs.er.usgs.gov/publication/pp729C ''Stratigraphic framework of the Absaroka Volcanic Supergroup in the Yellowstone National Park region.''] Professional Paper no. 729-C, U. S. Geological Survey, Reston, Virginia. 33 pp.</ref>

==Yellowstone Petrified Forest==
Within the Specimen Ridge, exposures of the Lamar River Formation is well known for the [[fossil]]s of upright standing, petrified tree trunks and multiple beds containing buried [[petrified forests]] and [[petrified wood]] concentrations. The concentrations of silicified wood, upright standing, petrified tree trunks, and associated buried petrified forests of Specimen Ridge and adjacent Amethyst Mountain are collectively known as ''Yellowstone Petrified Forest''. They have been known to science and studied for over 130 years.<ref name="Holmes1879a">Holmes, WH (1879) ''Fossil forests of the volcanic Tertiary formation of Yellowstone National Park. Geological and Geographical Survey of the Territories.'' Bulletin of the Survey vol. 5, no. 1, pp. 125-132. United States Geological and Geographical Survey, Department of the Interior, Washington DC</ref><ref name="Knowlton1914a">Knowlton, FH (1914) [https://web.archive.org/web/20070617231207/http://www.nps.gov/history/history/online_books/yell/knowlton/sec1.htm ''The Fossil Forests of Yellowstone National Park.''] National Park Service, Department of the Interior, Office of the Secretary, Washington DC. 31 pp. Last accessed September 26, 2013.</ref><ref name="Dorf1960a">Dorf, E (1960) ''Tertiary fossil forests of Yellowstone National Park, Wyoming.'' in DE Campau, HW Anisgard, and RL Egbet, pp. 253-260, Guidebook, 11th Annual Field Conference, Billings Geological Society, Casper, Wyoming.</ref><ref name="Dorf1964a">Dorf, E (1964) ''The 'petrified forests' of Yellowstone Park.'' Scientific American. 210(4):106-114.</ref><ref name="Dorf1980a">Dorf, E (1980) [https://archive.org/details/petrifiedforests00nati ''Petrified Forests of Yellowstone.''] National Park Service, U.S. Department of Interior, Washington, D.C., 31 pp.</ref>

Within Specimen Ridge, the Yellowstone Petrified Forest consists of a mixture of fossilized, in place (''[[in situ]]'') buried forests and beds of transported logs and stumps. The rare beds that contain buried forests were buried in place (''[[in situ]]'') by volcanic lahars and braided streams. The concentrations of fossilized upright stumps, flat-lying logs, and logs lying at various angles were transported from the higher slopes of adjacent volcanoes and buried by either volcanic lahars or braided and meandering streams.<ref name="Fritz1980a"/><ref name="Fritz1981a"/><ref name="Fritz1982a"/><ref name="KaroweOthers1987a">Karowe, AL. and TH Jefferson (1987) ''Burial of trees by eruptions of Mount St. Helens, Washington; implications for the interpretation of fossil forests.'' Geological Magazine. 124(3):191-204.</ref> Notably, the [[1980 eruption of Mount St. Helens]], and other [[Quaternary]] and [[Holocene]] [[eruptions]] of other [[Cascade Range]] volcanoes have created virtually identical beds containing either the buried upright standing trunks of forests, transported logs and upright stumps, or a combination of both. These beds consist of a mixture of lahars and stream deposits.<ref name="KaroweOthers1987a"/><ref name="Fritz1983a">Fritz, WJ (1983) ''Comment on 'Erect floating stumps in Spirit Lake, Washington' '' Geology 11(12):733-734</ref><ref name="Fritz1980c">Fritz, WJ, (1980c) ''Reinterpretation of the depositional environment of the Yellowstone "fossil forests".'' Geology. 8:(7):309-313.</ref><ref name="FritzOther1985a">Fritz, WJ, and S Harrison (1985) ''Transported trees from the 1982 Mount St. Helens sediment flows--Their use as paleocurrent indicators.'' Sedimentary Geology 42(1-2):49-64.</ref><ref name="CameronOthers1991a">Cameron, KA, and PT Pringle (1991) [http://www.fsl.orst.edu/wpg/events/S05/91Cameron&Pringle_buried_forestspdf.pdf ''Prehistoric buried forests of Mount Hood.''] Oregon geology. 53(2):34-43.</ref> Prehistoric logs and upright trunks that are buried in Late Pleistocene lahar and stream deposits of Mount St. Helens were found to be the initial stages of being naturally petrified by [[silica]].<ref name="KaroweOthers1987a"/>

In regard to these fossil forests and other fossils, collecting of fossils in Yellowstone National Park is illegal. In addition, visitors should stay on marked and maintained trails.<ref name="Dorf1960a"/>

{{gallery
|title=Images of Specimen Ridge
|footer=
|width=150
|File:YellowstonePetrifiedForest01.jpg|Fossilized trees on Specimen Ridge
|File:FossilTreeSpecimenRidgeYNP1890.jpg|Fossil Tree, Specimen Ridge, 1890
|File:PetrifiedForestSpecimenRidgeYNP1938.jpg|Location of the [[petrified wood|petrified forest]] on Specimen Ridge, 1938
|File:SpecimenRidgeYNP1977.jpg|Specimen Ridge from Specimen Ridge Trail, 1977
|File:SpecimenRidgeFromMountWashburnYNP.jpg|Specimen Ridge from [[Mount Washburn]], 1977
}}

==See also==
* [[Erling Dorf]]
* [[Mountains and mountain ranges of Yellowstone National Park]]

==References==
{{reflist}}

==External links==
* Anonymous (nd) [https://www.nps.gov/features/yell/slidefile/geology/paleontology/Page.htm ''Petrified Forest''], [https://www.nps.gov/features/yell/slidefile/index.htm Yellowstone Photo Collection], [https://www.nps.gov/yell/index.htm Yellowstone National Park], National Park Service, Washington DC.
* Viney, M (2008) [http://petrifiedwoodmuseum.org/SpecimenRidge.htm ''Specimen Ridge''], [http://petrifiedwoodmuseum.org/Index.htm The Virtual Petrified Wood Museum.]

{{Mountains of Wyoming}}
{{Tower Roosevelt}}
{{Wyoming}}
{{Petrified forests}}

[[Category:Ridges of Wyoming]]
[[Category:Landforms of Yellowstone National Park]]
[[Category:Landforms of Park County, Wyoming]]
[[Category:Petrified forests]]
[[Category:Tourist attractions in Park County, Wyoming]]
[[Category:Paleontology in Wyoming]]