The Green River Formation is an Eocene geologic formation that records the sedimentation in a series of intermontane lakes. The sedimentary layers were formed in a large area of interconnecting lakes, named for the present-day Green River, a tributary of the Colorado River. The area of the formation exists as three separate basins around the Uinta Mountains of northeastern Utah: an area in northwestern Colorado east of the Uintas, a larger area in the southwest corner of Wyoming just north of the Uintas known as Lake Gosiute, and the largest area, which lies in northeastern Utah and western Colorado south of the Uintas, known as Lake Uinta. Fossil Butte National Monument in Lincoln County, Wyoming is located in a part of the formation known as Fossil Lake because of the abundance of exceptionally well preserved fish fossils found in the area. The Eocene epoch (56-34 Ma) is a major division of the geologic timescale and the second epoch of the Palaeogene period in the Cenozoic era. ... The Green River, a tributary of the Colorado, is shown highlighted on a map of the western United States. ... The Colorado River from the bottom of Marble Canyon, in the Upper Grand Canyon Colorado River in the Grand Canyon from Desert View The Colorado River is a river in the southwestern United States and northwestern Mexico, approximately 1,450 mi (2,330 km) long, draining a part of the... This view of Kings Peak shows the cliff bands and basins typical throughout the Uintas. ... Official language(s) English Capital Salt Lake City Largest city Salt Lake City Area  Ranked 13th  - Total 84,876 sq. ... Official language(s) English Capital Denver Largest city Denver Area  - Total   - Width   - Length    - % water  - Latitude  - Longitude Ranked 8th 104,185 sq mi  269 837 km² 280 miles  451 km 380 miles  612 km 0. ... Official language(s) English Capital Cheyenne Largest city Cheyenne Area  Ranked 10th  - Total 97,872 sq. ... Fossil Butte National Monument is a unit of the National Park Service located in Kemmerer, Wyoming; the national monument was founded on October 23, 1972. ... Lincoln County is a county located in the state of Wyoming. ...

The formation of the intermontane lake environment in the area during the Eocene was a result of the late Cretaceous Sevier orogeny to the west and the uplift of the Rocky Mountains during the Paleogene Laramide orogeny. The Eocene sedimentary basins thus received sediments from all directions. The Uinta uplift shed sediments north, east and south into the basins. The Wind River Mountains of west central Wyoming provided sediments from the north into the Green River basin. The Front Range, the Park Range and the Sawatch Range of the Colorado Rockies provided sediments into the basins from the east. The Uncompahgre geanticline and the San Juan Mountains provided sediments from the south. To the west were the Wasatch Mountains of Utah and the ranges of eastern Idaho. The Cretaceous period is one of the major divisions of the geologic timescale, reaching from the end of the Jurassic period, about 146 million years ago (Ma), to the beginning of the Paleocene epoch of the Tertiary period (65. ... The Sevier orogeny was a mountain-building event that affected western North America between aproximately 140 million years ago (Ma), and 50 Ma. ... White Goat Wilderness Area, Alberta, Canada View of the Rocky Mountains as depicted on the Colorado state quarter The Rocky Mountains, often called the Rockies, are a broad mountain range in western North America. ... Paleogene (alternatively Palaeogene) period is a unit of geologic time that began 65 and ended 23 million years ago. ... The Laramide orogeny was a 30 million year period of mountain building in western North America that started in the Late Cretaceous, 70 million years ago, and ended in the Late Paleogene 40 million years ago. ... The Wind River Range is shown highlighted on a map of the western United States The Wind River Range is a sub-range of the Rocky Mountains in western Wyoming in the United States. ... The Front Range is shown highlighted on a map of the western United States The Front Range is a mountain range in the United States on the eastern edge of the Rocky Mountains, and on the western edge of the Great Plains. ... The Park Range (elevation approximately 12,000 ft) is a mountain range in the Rocky Mountains of northwestern Colorado in the United States. ... The Sawatch Range (sometimes Saguache Range) is a mountain range in central Colorado containing several of the Rocky Mountains highest peaks, including Mount Elbert, at 14,440 ft (4,401 m) the highest peak in the Rockies. ... The Uncompahgre Plateau in western Colorado is a distinctive large uplift part of the Colorado Plateau rising to elevations around 10,000 feet. ... The San Juan Mountains are a rugged mountain range in the Rocky Mountains in southwestern Colorado. ... The Wasatch Range (also seen as Wasatch Mountains and Wahsatch Range) is a mountain range that stretches from southern Idaho and Wyoming south through central Utah in the Western United States. ...

The lithology of these landlocked lake sediments is varied and includes sandstones, mudstones, siltstones, oil shales, coal beds, saline evaporite beds, and a variety of lacustrine limestones and dolostones. Volcanic ash layers within the various sediments from the active Absaroka Volcanic field to the north in the vicinity of Yellowstone and the San Juan volcanic field to the southeast provide dateable horizons within the sediments. Petrology is a field of geology which focuses on the study of rocks and the conditions by which they form. ... Sandstone near Stadtroda, Germany Sandstone is a sedimentary rock composed mainly of sand-size mineral or rock grains. ... Mudstone is a fine-grained sedimentary rock whose original constituents were clays or muds. ... Categories: Stub | Sedimentary rocks ... Oil shale is a general term applied to a group of fine black to dark brown shales rich enough in organic material (called kerogen) to yield petroleum upon distillation. ... Coal (previously referred to as pitcoal or seacoal) is a fossil fuel extracted from the ground by underground mining or open-pit mining (surface mining). ... Evaporites are water-soluble, mineral sediments that result from the evaporation of saline water. ... Limey shale overlaid by limestone. ... Dolostone is a sedimentary carbonate rock that contains a high percentage of the mineral dolomite. ... Diamond Head, a well-known backdrop to Waikiki in Hawaii, is an ash cone that solidified into tuff Volcanic ash is the term for very fine rock and mineral particles less than 2 mm in diameter that are ejected from a volcanic vent. ... The Absaroka Range is shown highlighted on a map of North America The Absaroka Range is a mountain range, a sub-range on the eastern side of the Rocky Mountains stretching for about 150 mi (240 km) across the Montana-Wyoming border, and forming the eastern boundary of Yellowstone National... Yellowstone National Park is a U.S. National Park located in the states of Idaho, Montana, and Wyoming. ... Radiometric dating is a technique used to date materials based on a knowledge of the decay rates of naturally occurring isotopes, and the current abundances. ...

The trona (hydrated sodium bicarbonate carbonate) beds of Sweetwater County, Wyoming are noted for a variety of rare evaporite minerals. The beds are the type locality for seven rare minerals: bradleyite, ewaldite, loughlinite, mckelveyite-(Y), norsethite, paralabuntsovite-Mg, and shortite as well as an occurrence of moissanite (SiC). Trona, hydrated sodium bicarbonate carbonate (Na3HCO3CO3·2H2O), is an evaporite mineral. ... Sweetwater County is a county located in the state of Wyoming. ... Moissanite is a trade name given to silicon carbide (chemical formula SiC) for use in the gem business. ...

Fossil zones

Within the Green River Formation of southwest Wyoming in the area known as Fossil Lake, two distinct zones of very fine-grained lime muds are particularily noted for preserving a variety of complete and detailed fossils. These layers are an Eocene Lagerstätte, a rare place where conditions were right for a rich accumulation of undisturbed fossils. The most productive zone—called the 18 inch layer— consists of a series of laminated or varved lime muds containing abundant fish and other fossils. These are easily split along the layers to reveal the fossils. This thin zone represents some 4000 years of deposition. The second fossil zone, the split fish layer, is an unlaminated layer about six feet thick that also contains abundant detailed fossils, but is harder to work because it is not composed of fissile laminae. A fossil Ammonite Fossils (from Latin fossus, literally having been dug up) are the mineralized or otherwise preserved remains or traces (such as footprints) of animals, plants, and other organisms. ... Lagerstätten (German, singular: Lagerstätte, literally: place(s) of storage or resting place(s)) are sedimentary deposits that exhibit extraordinary fossil richness or completeness. ... A varve is an annual layer of sediment or sedimentary rock. ...

The limestone matrix is so fine-grained that fossils include rare soft parts of complete insects and fallen leaves in spectacular detail. More than twenty-two orders of insects are represented in the Green River collection at the Smithsonian Institution in Washington, D.C. alone. The Smithsonian Institution Building or Castle on the National Mall serves as the Institutions headquarters. ...

The Green River fossils date about 48 mya, but cover several million years, including the transition between the moist early Eocene climate and the slightly drier mid-Eocene. The climate was moist and mild enough to support crocodiles, which do not tolerate frost, and the lakes were surrounded by sycamore forests. As the lake configurations shifted, each Green River location is distinct in character and time. The lake system formed over underlying river deltas and shifted in the flat landscape with slight tectonic movements, receiving sediments from the Uinta highland and the Rocky Mountains to the east and north. The lagerstätten formed in anoxic conditions in the fine carbonate muds that formed in the lakebeds. Lack of oxygen slowed bacterial decomposition and kept scavengers away, so leaves of palms, ferns and sycamores, some showing the insect damage they had sustained during their growth, were covered with fine-grained sediment and preserved. Insects were preserved whole, even delicate wing membranes and spider spinnerets. Genera Mecistops Crocodylus Osteolaemus See full taxonomy. ... MEG ILLIF 1630 260 2894 ... White Goat Wilderness Area, Alberta, Canada View of the Rocky Mountains as depicted on the Colorado state quarter The Rocky Mountains, often called the Rockies, are a broad mountain range in western North America. ...

Vertebrates were preserved too, including the scales of Boreasuchus, the crocodile that was an early clue to the mild Eocene climate of Western North America. Fish are common. The fossils of the herring-like Knightia, sometimes in dense layers, as if a school had wandered into anoxic water levels and were overcome, are familiar to fossil-lovers and are among the most commonly available fossils on the commercial market. Approximately sixty vertebrate taxa in all have been found at Green River. Besides fishes they include at least eleven species of reptiles, and some birds and one slothlike mammal, Brachianodon westorum, with some scattered vertebrae of others, like the dog-sized Meniscotherium and Notharctus, one of the first primates. The earliest known bat, already full-developed for flight, is found here. Even a snake, Boavus idelmani, found its way into a lake and was preserved in the mudstone. Suborders Megachiroptera Microchiroptera See text for families. ...

Discovery of the fossil beds

A Dr. John Evans collected and had described the first fossil fish from the Green River beds in 1856. The specimen was identified as Knightia eocaena. Edward Drinker Cope collected extensively from the area and produced a publication on the fossil fishes in 1871. 1856 was a leap year starting on Tuesday (see link for calendar). ... Fossil of Knightia Knightia is an extinct genus of fish well-known from abundant fossils found in the Green River Formation of Wyoming (USA). ... Edward Drinker Cope Edward Drinker Cope (July 28, 1840–April 12, 1897) was an American paleontologist and comparative anatomist. ... 1871 (MDCCCLXXI) was a common year starting on Sunday (see link for calendar). ...

Millions of fish fossils have been collected from the area.

References

• Geologic Atlas of the Rocky Mountain Region, Rocky Mountain Association of Geologists, 1972, Denver Colorado
• King, Philip B., 1977, The Evolution of North America, Revised edition, Princeton University Press
• Gaggiano, Tom, The Green River Formation http://www.fossilnews.com/2000/grnrv/grnrv.html Accessed March 18, 2006.
• Carrol, Alan, 2001, Green River research project, http://www.geology.wisc.edu/~carroll/green_river.html Accessed March 18, 2006.
• Minerals of the Green River Formation, Sweetwater County, Wyoming, Mindat
• Green River FormationUCMP Berkeley website
• Eocene fossils from the Green River Formation
• Fossil fish of the Green River Formation
• Paleobiology Database: Icaronycteris Type Locality: Wasatchian, Wyoming, aka Fossil Lake, Green River
• Paleobiology Database Green River Quarry: Kimmeridgian - Tithonian, Utah
• Paleobiology Database: BYU Locality #712, Uintah Basin, Green River Formation, Utah: Eocene - Eocene, Utah
• Green River Formation and Shale Oil, Research Brief by Rand [1]