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Polystrate Fossil
A polystrate fossil is a fossil of a single organism (such as a tree trunk) that extends through more than one geological stratum.MacRae, A., 1997''"Polystrate" Tree Fossils'' This term is typically applied to "fossil forests" of upright fossil tree trunks and stumps that have been found worldwide, i.e. in the Eastern United States, Eastern Canada, England, France, Germany, and Australia, typically associated with coal-bearing strata.DiMichele, W.A., and H.J. Falcon-Lang, 2011''Pennsylvanian 'fossil forests' in growth position (T0 assemblages): origin, taphonomic bias and palaeoecological insights.''Journal of the Geological Society, 168(2):585-605. Within Carboniferous coal-bearing strata, it is also very common to find what are called ''Stigmaria'' (root stocks) within the same stratum. Stigmaria are completely absent in post-Carboniferous strata, which contain either coal, polystrate trees, or both. The word ''polystrate'' is not a standard geological term. This term is typ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lycopsid Joggins Mcr1
Lycopodiopsida is a class of vascular plants known as lycopods, lycophytes or other terms including the component lyco-. Members of the class are also called clubmosses, firmosses, spikemosses and quillworts. They have dichotomously branching stems bearing simple leaves called microphylls and reproduce by means of spores borne in sporangia on the sides of the stems at the bases of the leaves. Although living species are small, during the Carboniferous, extinct tree-like forms formed huge forests that dominated the landscape and contributed to coal deposits. The nomenclature and classification of plants with microphylls varies substantially among authors. A consensus classification for extant (living) species was produced in 2016 by the Pteridophyte Phylogeny Group (PPG I), which places them all in the class Lycopodiopsida, which includes the classes Isoetopsida and Selaginellopsida used in other systems. (See Table 2.) Alternative classification systems have used ranks f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Deposition (sediment)
Deposition is the geological process in which sediments, soil and rocks are added to a landform or landmass. Wind, ice, water, and gravity transport previously weathered surface material, which, at the loss of enough kinetic energy in the fluid, is deposited, building up layers of sediment. Deposition occurs when the forces responsible for sediment transportation are no longer sufficient to overcome the forces of gravity and friction, creating a resistance to motion; this is known as the null-point hypothesis. Deposition can also refer to the buildup of sediment from organically derived matter or chemical processes. For example, chalk is made up partly of the microscopic calcium carbonate skeletons of marine plankton, the deposition of which has induced chemical processes (diagenesis) to deposit further calcium carbonate. Similarly, the formation of coal begins with the deposition of organic material, mainly from plants, in anaerobic conditions. Null-point hypothesis The null ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eocene
The Eocene ( ) Epoch is a geological epoch (geology), epoch that lasted from about 56 to 33.9 million years ago (mya). It is the second epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), Era. The name ''Eocene'' comes from the Ancient Greek (''ēṓs'', "dawn") and (''kainós'', "new") and refers to the "dawn" of modern ('new') fauna that appeared during the epoch. The Eocene spans the time from the end of the Paleocene Epoch to the beginning of the Oligocene Epoch. The start of the Eocene is marked by a brief period in which the concentration of the carbon isotope Carbon-13, 13C in the atmosphere was exceptionally low in comparison with the more common isotope Carbon-12, 12C. The end is set at a major extinction event called the ''Grande Coupure'' (the "Great Break" in continuity) or the Eocene–Oligocene extinction event, which may be related to the impact of one or more large bolides in Popigai impact structure, Siberia and in what is now ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lahar
A lahar (, from jv, ꦮ꧀ꦭꦲꦂ) is a violent type of mudflow or debris flow composed of a slurry of pyroclastic material, rocky debris and water. The material flows down from a volcano, typically along a river valley. Lahars are extremely destructive: they can flow tens of metres per second, they have been known to be up to deep, and large flows tend to destroy any structures in their path. Notable lahars include those at Mount Pinatubo and Nevado del Ruiz, the latter of which killed thousands of people in the town of Armero. Etymology The word ''lahar'' is of Javanese origin. Berend George Escher introduced it as a geological term in 1922. Description The word ''lahar'' is a general term for a flowing mixture of water and pyroclastic debris. It does not refer to a particular rheology or sediment concentration. Lahars can occur as normal stream flows (sediment concentration of less than 30%), hyper-concentrated stream flows (sediment concentration between 30 and 60% ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Yellowstone National Park
Yellowstone National Park is an American national park located in the western United States, largely in the northwest corner of Wyoming and extending into Montana and Idaho. It was established by the 42nd U.S. Congress with the Yellowstone National Park Protection Act and signed into law by President Ulysses S. Grant on March 1, 1872. Yellowstone was the first national park in the U.S. and is also widely held to be the first national park in the world. The park is known for its wildlife and its many geothermal features, especially the Old Faithful geyser, one of its most popular. While it represents many types of biomes, the subalpine forest is the most abundant. It is part of the South Central Rockies forests ecoregion. While Native Americans have lived in the Yellowstone region for at least 11,000 years, aside from visits by mountain men during the early-to-mid-19th century, organized exploration did not begin until the late 1860s. Management and control of the park ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Specimen Ridge
Specimen Ridge, el. is an approximately 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. The south side of the ridge is traversed by the Specimen Ridge Trail between Tower Junction and Soda Butte Creek. The trail passes through the Petrified Forest and over the summit of Amethyst Mountain el. .Schneider, Bill (2003) ''Hiking Yellowstone National Park.'' Falcon Press, Guilford, Connecticut. 101 pp. (pp. 199–202) 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 conglom ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Amethyst Mountain
Amethyst Mountain, el. is the highest peak and central part of a northwest – southeast trending ridge that lies between the Lamar River to the northeast and Deep Creek to the southwest within Park County, Wyoming. From northwest to southeast, this ridge consists of Specimen Ridge, Amethyst Mountain, and the Mirror Plateau in Yellowstone National Park. The nearest town is Silver Gate, Montana, which is 19.2 miles away.US Geological Survey (1986) ''Amethyst Mountain Quadrangle Wyoming-Park Co. 7.5-minute series topographic.'' scale 1:24,000, US Geological Survey, Denver, Colorado.US Geological Survey (1989) ''Opal Creek Quadrangle Wyoming-Park Co. 7.5-minute series topographic.'' scale 1:24,000, US Geological Survey, Denver, Colorado. In 1872, it was named Amethyst Mountain by the United States Geological Survey for amethysts found on its summit.Gannett, Henry (1905) ''The Origin of Certain Place Names in the United States.'' Bulletin no. 258, United States Geological Survey, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gallatin Range
The Gallatin Range is a mountain range of the Rocky Mountains, located in the U.S. states of Montana and Wyoming. It includes more than 10 mountains over . The highest peak in the range is Electric Peak at . The Gallatin Range was named after Albert Gallatin, the longest-serving United States Secretary of the Treasury, US Secretary of the Treasury. The range extends north to south and averages in width. Geography The southernmost peaks of the range are in the northwestern section of Yellowstone National Park. However, the majority of the range is in Gallatin National Forest. The Yellowstone River flows north on the eastern flank of the range. The Madison Range parallels the Gallatins to the west. The northern end of the range is near Livingston, Montana and Bozeman Pass separates the Gallatins from the Bridger Mountains (Montana), Bridger Mountains to the north. The range is an integral part of the Greater Yellowstone Ecosystem and has grizzly bears, Gray Wolf, wolves and oth ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pull-apart Basin
In geology, a basin is a region where subsidence generates accommodation space for the deposition of sediments. A pull-apart basin is a structural basin where two overlapping (en echelon) strike-slip faults or a fault bend creates an area of crustal extension undergoing tension, which causes the basin to sink down. Frequently, the basins are rhombic or sigmoidal in shape. Dimensionally, basins are limited to the distance between the faults and the length of overlap.Frisch, Wolfgang, Martin Meschede, and Ronald C. Blakey. ''Plate tectonics: Continental drift and mountain building''. Springer, 2010. Pull-apart basins are also referred to as overlapping-tension-zones (OTZ). Mechanics and fault configuration The inhomogeneity and structural complexity of continental crust causes faults to deviate from a straight course and frequently causes bends or step-overs in fault paths. Bends and step-overs of adjacent faults become favorable locations for extensional and compressional str ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Joggins, Nova Scotia
Joggins is a rural community located in western Cumberland County, Nova Scotia, Canada. On July 7, 2008 a 15-km length of the coast constituting the Joggins Fossil Cliffs was officially inscribed on the World Heritage List.UNESCO portal History The area was known to the as "Chegoggins" meaning place of the large fish weir, a name modified by French and English settlers to Joggins. Situated on the Cumberland Basin, a sub-basin of the Bay of Fund ...[...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Continental Margin
A continental margin is the outer edge of continental crust abutting oceanic crust under coastal waters. It is one of the three major zones of the ocean floor, the other two being deep-ocean basins and mid-ocean ridges. The continental margin consists of three different features: the continental rise, the continental slope, and the continental shelf. The continental shelf is the relatively shallow water area found in proximity to continents. Continental margins constitute about 28% of the oceanic area. Zones of the continental margin The continental shelf is the portion of the continental margin that transitions from the shore out towards to ocean. Continental shelves are believed to make up 7% of the sea floor. The width of continental shelves worldwide varies in the range of 0.03–1500 km. The continental shelf is generally flat, and ends at the shelf break, where there is a drastic increase in slope angle: The mean angle of continental shelves worldwide is 0° 07′, an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Salt Tectonics
upright=1.7 Salt tectonics, or halokinesis, or halotectonics, is concerned with the geometries and processes associated with the presence of significant thicknesses of evaporites containing rock salt within a stratigraphic sequence of rocks. This is due both to the low density of salt, which does not increase with burial, and its low strength. Salt structures (excluding undeformed layers of salt) have been found in more than 120 sedimentary basins around the world. Passive salt structures Structures may form during continued sedimentary loading, without any external tectonic influence, due to gravitational instability. Pure halite has a density of 2160 kg/m3. When initially deposited, sediments generally have a lower density of 2000 kg/m3, but with loading and compaction their density increases to 2500 kg/m3, which is greater than that of salt. Once the overlying layers have become denser, the weak salt layer will tend to deform into a characteristic series of rid ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
