Specimen Ridge
Specimen Ridge, el. 8,379 feet (2,554 m) is an approximately 8.5-mile (13.7 km) ridge along the south rim of the 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.[2] The south side of the ridge is traversed by the 18.8-mile (30.3 km) Specimen Ridge Trail between Tower Junction and Soda Butte Creek. The trail passes through the Petrified Forest[3] and over the summit of Amethyst Mountain el. 9,614 feet (2,930 m).[4]
Geology
Specimen Ridge consists of a geological formation known as the Lamar River Formation. Within the Specimen Mountain area, it consists predominantly of an undetermined thickness of conglomerate that is interbedded with lesser proportions of tuffaceous sandstone and siltstone. Volcanic breccia is absent. The conglomerates consist of a mixture of mudflow deposits (lahars) that are complexly interlayered with braided and 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 1 cm (0.39 in) to 2 meters (6.6 ft) 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 1 cm (0.39 in) to 30 cm (12 in). 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.[5][6][7][8][9]
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 8,000 feet (2,400 m) to 10,000 feet (3,000 m) above adjacent intermountain valleys. Depending on location, the Lamar River Formation unconformably overlies either older lavas, conglomerates, tuffs, volcanic breccias of the Sepulcher Formation; Mississippian limestones and dolomites; or Precambrian gneiss. Based on radiometric dates and plant fossils from it, the Lamar River Formation is considered to be of Middle Eocene age.[5][10]
Yellowstone Petrified Forest
Within the Specimen Ridge, exposures of the Lamar River Formation is well known for the fossils 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.[11][12][13][14][15]
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.[5][7][8][16] 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.[16][17][18][19][20] 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.[16]
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.[13]
- Fossilized trees on Specimen Ridge
- Fossil Tree, Specimen Ridge, 1890
- Location of the petrified forest on Specimen Ridge, 1938
- Specimen Ridge from Specimen Ridge Trail, 1977
- Specimen Ridge from Mount Washburn, 1977
See also
References
- ^ a b "Specimen Ridge". Geographic Names Information System. United States Geological Survey, United States Department of the Interior. Retrieved 2009-12-31.
- ^ Whittlesey, Lee (1988) Yellowstone Place Names. Montana Historical Society Press, Helena, Montana. 145 pp. ISBN 0-917298-15-2
- ^ Knowlton, F. H. (1914) 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.
- ^ Schneider, Bill (2003) Hiking Yellowstone National Park. Falcon Press, Guilford, Connecticut. 101 pp. ISBN 0-7627-2539-7 (pp. 199–202)
- ^ a b c Fritz, WJ (1980a) Depositional Environment of the Eocene Lamar River Formation in Yellowstone National Park. Doctoral Dissertation, The University of Montana, Missoula, Montana.
- ^ Fritz, WJ (1980b) Stratigraphic framework of the Lamar River formation in Yellowstone National Park. Northwest Geology. vol. 9, pp. 1-18.,
- ^ a b Fritz, WJ (1981) Reinterpretation of the depositional environment of the Yellowstone fossil forests: Reply. Geology. 9(2):53-54.
- ^ a b 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.
- ^ 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.
- ^ Smedes, HW, and HJ Prostka, 1972, 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.
- ^ 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
- ^ Knowlton, FH (1914) 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.
- ^ a b 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.
- ^ Dorf, E (1964) The 'petrified forests' of Yellowstone Park. Scientific American. 210(4):106-114.
- ^ Dorf, E (1980) Petrified Forests of Yellowstone. National Park Service, U.S. Department of Interior, Washington, D.C., 31 pp.
- ^ a b c 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.
- ^ Fritz, WJ (1983) Comment on 'Erect floating stumps in Spirit Lake, Washington' Geology 11(12):733-734
- ^ Fritz, WJ, (1980c) Reinterpretation of the depositional environment of the Yellowstone "fossil forests". Geology. 8:(7):309-313.
- ^ 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.
- ^ Cameron, KA, and PT Pringle (1991) Prehistoric buried forests of Mount Hood. Oregon geology. 53(2):34-43.
External links
- Anonymous (nd) Petrified Forest, Yellowstone Photo Collection, Yellowstone National Park, National Park Service, Washington DC.
- Viney, M (2008) Specimen Ridge, The Virtual Petrified Wood Museum.
- v
- t
- e
- Abiathar Peak
- Atkins Peak
- Barronette Peak
- Breccia Peak
- Clayton Mountain
- Colter Peak
- Druid Peak
- Eagle Peak
- Fortress Mountain
- Francs Peak
- Index Peak
- Mount Chittenden
- First Peoples Mountain
- Mount Hornaday
- Mount Langford
- Mount Norris
- Mount Schurz
- Mount Stevenson
- Pilot Peak
- Sheep Mesa
- The Thunderer
- Washakie Needles
- Younts Peak
Bear Lodge Mountains | |
---|---|
Others |
- Antler Peak
- Bannock Peak
- Bunsen Peak
- Clagett Butte
- Dome Mountain (Park County)
- Echo Peak
- Gray Peak
- Joseph Peak
- Mount Everts
- Mount Haynes
- Mount Holmes
- Mount Jackson
- Purple Mountain
- Quadrant Mountain
- Sepulcher Mountain
- Terrace Mountain
- Three Rivers Peak
- Trilobite Point
- White Peaks
- Darwin Peak
- Doubletop Peak
- Sheep Mountain
- Elk Mountain (Carbon County)
- Medicine Bow Peak
- Albright Peak
- Battleship Mountain
- Bivouac Peak
- Buck Mountain
- Cathedral Group
- Cleaver Peak
- Cloudveil Dome
- Disappointment Peak
- Doane Peak
- Dry Ridge Mountain
- Eagles Rest Peak
- Elk Mountain (Teton County)
- Forellen Peak
- Fossil Mountain
- Grand Teton
- Green Lakes Mountain
- Housetop Mountain
- The Jaw
- Littles Peak
- Maidenform Peak
- Middle Teton
- Moose Mountain
- Mount Bannon
- Mount Glory
- Mount Hunt
- Mount Jedediah Smith
- Mount Meek
- Mount Moran
- Mount Owen
- Mount Saint John
- Mount Wister
- Mount Woodring
- Mount Woodrow Wilson
- Nez Perce Peak
- Owl Peak
- Prospectors Mountain
- Rammell Mountain
- Ranger Peak
- Raynolds Peak
- Red Mountain
- Rendezvous Mountain
- Rendezvous Peak
- Rock of Ages
- Rockchuck Peak
- Rolling Thunder Mountain
- Shadow Peak
- South Teton
- Spearhead Peak
- Static Peak
- Survey Peak
- Symmetry Spire
- Table Mountain
- Teepe Pillar
- Teewinot Mountain
- Temple Peak
- Thor Peak
- Traverse Peak
- Veiled Peak
- The Wall
- Window Peak
- American Legion Peak
- Atlantic Peak
- Bair Peak
- Bastion Peak
- Bastion Peak-Northeast Peak
- Bears Ears Mountain
- Big Sandy Mountain
- Block Tower
- Bow Mountain
- Brown Cliffs North
- Cathedral Peak
- Desolation Peak
- Dog Tooth Peak
- Dome Mountain (Hot Springs County)
- Doublet Peak
- Downs Mountain
- East Temple Peak
- Flagstone Peak (Fremont County)
- Fremont Peak
- Gannett Peak
- Harrower Peak
- Henderson Peak
- Jackson Peak
- Klondike Peak
- Knife Point Mountain
- Lander Peak
- Lizard Head Peak
- Mitchell Peak
- Mount Bonneville
- Mount Chauvenet
- Mount Febbas
- Mount Helen
- Mount Hooker
- Mount Koven
- Mount Lander
- Mount Nystrom
- Mount Owen
- Mount Sacagawea
- Mount Warren
- Mount Washakie
- Mount Whitecap
- Overhanging Tower
- Payson Peak
- Pingora Peak
- Pylon Peak
- Raid Peak
- Rampart Peak
- Roaring Fork Mountain
- Roberts Mountain
- Shale Mountain
- Sharks Nose
- South Downs Mountain
- The Sphinx
- Split Mountain
- Sunbeam Peak
- Three Waters Mountain
- Torrey Peak
- Turret Peak
- Twin Peaks
- Union Peak
- Valentine Mountain
- Valentine Peak
- War Bonnet Peak
- Warrior Peaks
- Watch Tower
- Whiskey Mountain
- Wind River Peak
- Wolfs Head
- Amethyst Mountain
- Aspen Mountain
- Barlow Peak
- Bridger Mountains
- Cook Peak
- Copper Mountain
- Dirty Mountain
- Douglas Knob
- Dunraven Peak
- Factory Hill
- Ferris Mountains
- Folsom Peak
- Garfield Peak
- Granite Mountains
- Granite Peak
- Heart Mountain
- Hedges Peak
- Hoyt Peak
- Jelm Mountain
- Mansface Hill
- Mount Hancock
- Mount Leidy
- Mount Sheridan
- Mount Washburn
- National Park Mountain
- Owl Creek Mountains
- Prospect Peak (Park County)
- Rawhide Buttes
- Roaring Mountain
- Sierra Madre Range
- Signal Mountain
- Snake River Range
- Specimen Ridge
- Sublette Mountain
- Tongue Butte
- Trischman Knob
- White Mountain
- Wilkins Peak