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Dorotea Formation
The Dorotea Formation is a geological formation in the Río de Las Chinas Valley of the Magallanes Basin in Patagonian Chile whose strata date back to the Campanian to Maastrichtian of the Late Cretaceous.Dorotea Formation at .org Description The Dorotea Formation was first described by Katz in 1963. The formation comprises s with frequent |
Geological Formation
A geological formation, or simply formation, is a body of rock having a consistent set of physical characteristics ( lithology) that distinguishes it from adjacent bodies of rock, and which occupies a particular position in the layers of rock exposed in a geographical region (the stratigraphic column). It is the fundamental unit of lithostratigraphy, the study of strata or rock layers. A formation must be large enough that it can be mapped at the surface or traced in the subsurface. Formations are otherwise not defined by the thickness of their rock strata, which can vary widely. They are usually, but not universally, tabular in form. They may consist of a single lithology (rock type), or of alternating beds of two or more lithologies, or even a heterogeneous mixture of lithologies, so long as this distinguishes them from adjacent bodies of rock. The concept of a geologic formation goes back to the beginnings of modern scientific geology. The term was used by Abraham Gottlob Wer ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sandstone
Sandstone is a clastic sedimentary rock composed mainly of sand-sized (0.0625 to 2 mm) silicate grains. Sandstones comprise about 20–25% of all sedimentary rocks. Most sandstone is composed of quartz or feldspar (both silicates) because they are the most resistant minerals to weathering processes at the Earth's surface. Like uncemented sand, sandstone may be any color due to impurities within the minerals, but the most common colors are tan, brown, yellow, red, grey, pink, white, and black. Since sandstone beds often form highly visible cliffs and other topographic features, certain colors of sandstone have been strongly identified with certain regions. Rock formations that are primarily composed of sandstone usually allow the percolation of water and other fluids and are porous enough to store large quantities, making them valuable aquifers and petroleum reservoirs. Quartz-bearing sandstone can be changed into quartzite through metamorphism, usually related to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aristonectinae
Aristonectinae is a clade of plesiosaurs in the family Elasmosauridae. It includes the Late Cretaceous plesiosaurs ''Aristonectes'' and ''Kaiwhekea'', traditionally grouped with the Late Jurassic ''Tatenectes'' and ''Kimmerosaurus'' in the family Aristonectidae The Aristonectidae is a taxonomic family of poorly known plesiosaurs from the Jurassic and Cretaceous periods. They are closely related to polycotylid plesiosaurs. The family is made up of ''Tatenectes'', ''Kimmerosaurus'', ''Aristonectes'', and .... References Late Cretaceous plesiosaurs {{cretaceous-reptile-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Yaminuechelys
''Yaminuechelys'' is an extinct genus of chelid turtle from Argentina and the Dorotea Formation of Chile. The genus first appeared during the Late Cretaceous and became extinct during the Late Paleocene.Bona, P. & De la Fuente, M. 2005. Phylogenetic and paleobiogeographic implications of ''Yaminuechelys major'' (Staesche, 1929) new comb., a large long-necked chelid turtle from the early Paleocene of Patagonia, Argentina. ''Journal of Vertebrate Paleontology'' 25(3):569–582. Species The genus contains the following two species: * ''Y. gasperinii'' - Late Cretaceous Allen, Anacleto, La Colonia Formations, Argentina''Yaminuechelys'' at Fossilworks.org * ''Y. maior'' - |
Aristonectes
''Aristonectes'' (meaning 'best swimmer') is an extinct genus of plesiosaur from the Late Cretaceous Paso del Sapo Formation of what is now Argentina, the Quiriquina Formation of Chile and the Lopez de Bertodano Formation of Antarctica. The type species is ''Aristonectes parvidens'', first named by Cabrera in 1941. Description Analysis of a specimen from the Lopez de Bertodano Formation indicates that ''Aristonectes'' was one of the largest plesiosaurs ever to exist, with an estimated body length of and body mass of per Paul and per O'Gorman and his colleagues. Classification ''Aristonectes'' was classified variously since its original 1941 description, but a 2003 review of plesiosaurs from Patagonia conducted by Gasparini ''et al.'' (2003) found that ''Aristonectes'' was most closely related to elasmosaurid plesiosaurs like ''Elasmosaurus''. The authors also considered '' Morturneria'' a junior synonym of ''Aristonectes'' because the former's holotype has unfu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Anura (frog)
Anura may refer to: Biology * Anura (frog), the order for frogs * ''Anura'' (plant), a genus of flowering plants in the daisy family People Anura is a common given name in Sri Lanka * Anura Bandaranaike (1949–2008), Sri Lankan politician * Anura Kumara Dissanayaka (born 1968), Sri Lankan politician * Anura Horatious, Sri Lankan novelist * Anura C. Perera (born 1947), Sri Lankan-American writer and astronomer * Anura Ranasinghe Anura Nandana Ranasinghe (13 October 1956, in Kalutara – 9 November 1998, in Colombo) was a former Sri Lankan cricketer, who represented Sri Lanka at international level 11 times in both Tests and ODIs. School times Ranasinghe won the best ... (1956–1998), Sri Lankan cricketer * Anura Rohana, Sri Lankan golfer * Anura Tennekoon (born 1946), Sri Lankan cricketer * Anura Wegodapola (born 1981), cricketer for Sri Lanka Navy * Anura Priyadharshana Yapa (born 1959), Sri Lankan politician Place * Anura, Varanasi, a village in Uttar Pradesh, India S ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sierra Baguales
Sierra Baguales or Sierra de los Baguales is a mountain range in the southernmost Andes. Sierra Baguales is a long east–west chain, secondary to the main chain of the Andes that lie further west. It lies along the border between Chile and Argentina near the localities of Puerto Natales and Río Turbio. Geology The mountain range contains a series of cirques formed by glaciers. Many cirques developed in the Pleistocene Epoch from isolated glaciers that existed separedly from ice sheets further west. The rocks of Sierra Baguales belong to various formations of Magallanes Basin. These rocks contain fossils of plants, mammals and marine invertebrates. Stratigraphy From top to bottom the following formations make up Sierra Baguales: * Santa Cruz Formation, sedimentary rocks belonging to a non-marine succession and hosting many vertebrate fossilsBostelmann et al., 2013 * Estancia 25 de Mayo Formation, a succession of fossil-bearing sedimentary rocks that date to the Early ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bartonian
The Bartonian is, in the ICS's geologic time scale, a stage or age in the middle Eocene Epoch or Series. The Bartonian Age spans the time between . It is preceded by the Lutetian and is followed by the Priabonian Age. Stratigraphic definition The Bartonian Stage was introduced by Swiss stratigrapher Karl Mayer-Eymar in 1857. The name derives from the coastal village Barton-on-Sea (part of New Milton) in southern England. The Barton Group, a lithostratigraphic unit from the south English Hampshire Basin, is of Bartonian age. The distinction between group and stage was made in the second part of the 20th century, when stratigraphers saw the need to distinguish between litho- and chronostratigraphy. The base of the Bartonian is at the first appearance of the calcareous nanoplankton species ''Reticulofenestra reticulata''. In 2009, an official reference profile (GSSP) for the base of the Bartonian had not yet been established. The top of the Bartonian Stage (the base of the Pria ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lutetian
The Lutetian is, in the geologic timescale, a stage or age in the Eocene. It spans the time between . The Lutetian is preceded by the Ypresian and is followed by the Bartonian. Together with the Bartonian it is sometimes referred to as the Middle Eocene Subepoch. Stratigraphic definition The Lutetian was named after Lutetia, the Latin name for the city of Paris. The Lutetian Stage was introduced in scientific literature by French geologist Albert de Lapparent in 1883 and revised by A. Blondeau in 1981. The base of the Lutetian Stage is at the first appearance of the nanofossil ''Blackites inflatus'', according to an official reference profile (GSSP) established in 2011. Of two candidates located in Spain, the Gorrondatxe section was chosen.See thwebsite of Eustoquio Molinafor these candidates. The top of the Lutetian (the base of the Bartonian) is at the first appearance of calcareous nanoplankton species ''Reticulofenestra reticulata''. The Lutetian overlaps with the Geisel ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Unconformity (geology)
An unconformity is a buried erosional or non-depositional surface separating two rock masses or strata of different ages, indicating that sediment deposition was not continuous. In general, the older layer was exposed to erosion for an interval of time before deposition of the younger layer, but the term is used to describe any break in the sedimentary geologic record. The significance of angular unconformity (see below) was shown by James Hutton, who found examples of Hutton's Unconformity at Jedburgh in 1787 and at Siccar Point in 1788. The rocks above an unconformity are younger than the rocks beneath (unless the sequence has been overturned). An unconformity represents time during which no sediments were preserved in a region or were subsequently eroded before the next deposition. The local record for that time interval is missing and geologists must use other clues to discover that part of the geologic history of that area. The interval of geologic time not represented ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Depositional Environment
In geology, depositional environment or sedimentary environment describes the combination of physical, chemical, and biological processes associated with the deposition of a particular type of sediment and, therefore, the rock types that will be formed after lithification, if the sediment is preserved in the rock record. In most cases, the environments associated with particular rock types or associations of rock types can be matched to existing analogues. However, the further back in geological time sediments were deposited, the more likely that direct modern analogues are not available (e.g. banded iron formations). Types of depositional environments Continental * – type of Fluvial deposit. Caused by moving water in a fan shape (Alluvial Fan) and containing mostly impermeable and nonporous sediments well sorted. * . Often in deserts and coastal regions and well sorted, large scale cross-beds * – processes due to moving water, mainly streams. Common sediments are grav ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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