|
Mesilla Valley Shale
The Mesilla Valley Shale is a geologic formation in southern New Mexico, northern Chihuahua, and far west Texas. It preserves fossils dating back to the Albian age of the early Cretaceous period. The formation is particularly well exposed at Cerro de Cristo Rey, near El Paso, Texas, where it is part of a thick sequence of uplifted Cretaceous beds that record transgressions (advances of the sea onto land) and regressions (retreats of the sea from the land) of the Western Interior Seaway during the mid-Cretaceous. Description The formation consists mostly of dark green to olive clay shale with some thin siltstone beds and highly fossiliferous calcareous beds. It lies conformably on the Muleros Formation and is conformably overlain by the Mojado Formation. Total thickness is . Lucas and his coinvestigators divide the formation into three informal members and interpret the lower two as a complete secondary deposition cycle and the upper as the base of the next deposition c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Formation (stratigraphy)
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 (geology), 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 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Regression (geology)
A marine regression is a geological process occurring when areas of submerged seafloor are exposed above the sea level. The opposite event, marine transgression, occurs when flooding from the sea covers previously-exposed land. Evidence of marine regressions and transgressions occurs throughout the fossil record, and the fluctuations are thought to have caused or contributed to several mass extinctions, such as the Permian-Triassic extinction event (250 million years ago) and Cretaceous–Paleogene extinction event (66 Ma). During the Permian-Triassic extinction, the largest extinction event in the Earth's history, the global sea level fell 250 m (820 ft). A major regression could itself cause marine organisms in shallow seas to go extinct, but mass extinctions tend to involve both terrestrial and aquatic species, and it is harder to see how a marine regression could cause widespread extinctions of land animals. Regressions are, therefore, seen as correlates or symptoms of major ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ammonoid
Ammonoids are a group of extinct marine mollusc animals in the subclass Ammonoidea of the class Cephalopoda. These molluscs, commonly referred to as ammonites, are more closely related to living coleoids (i.e., octopuses, squid and cuttlefish) than they are to shelled nautiloids such as the living ''Nautilus'' species. The earliest ammonites appeared during the Devonian, with the last species vanishing during the Cretaceous–Paleogene extinction event. Ammonites are excellent index fossils, and linking the rock layer in which a particular species or genus is found to specific geologic time periods is often possible. Their fossil shells usually take the form of planispirals, although some helically spiraled and nonspiraled forms (known as heteromorphs) have been found. The name "ammonite", from which the scientific term is derived, was inspired by the spiral shape of their fossilized shells, which somewhat resemble tightly coiled rams' horns. Pliny the Elder ( 79 AD near Pomp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Heteraster
''Heteraster'' is an extinct genus of sea urchins belonging to the family Toxasteridae. These slow-moving shallow infaunal deposit feeder-detritivores lived during the Cretaceous The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of th ... period. Fossils of this family have been found in the sediments of Algeria, Egypt, France, Hungary, Mexico, Peru, Portugal, Serbia and Montenegro, Spain, Switzerland and Yemen. Species *''Heteraster oblongus'' Brongniart, 1821 *''Heteraster delgadoi'' (Loriol, 1888) *''Heteraster renevieri'' (Desor, 1858). *''Heteraster transiens'' Devries (1956) *''Heteraster tissoti'' Coquand *''Heteraster peroni'' Ficheur *''Heteraster castellon'' References Spatangoida Cretaceous echinoderms Cretaceous animals of Africa Fossil taxa described in 1855 Fos ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Turritella
''Turritella'' is a genus of medium-sized sea snails with an operculum, marine gastropod mollusks in the family Turritellidae.Vos, C.; Gofas, S. (2013). Turritella Lamarck, 1799. Accessed through: World Register of Marine Species at http://www.marinespecies.org/aphia.php?p=taxdetails&id=138615 on 2013-06-02 They have tightly coiled shells, whose overall shape is basically that of an elongated cone. The name ''Turritella'' comes from the Latin word ''turritus'' meaning "turreted" or "towered" and the diminutive suffix ''-ella''. Species Valid Valid species within the genus ''Turritella'' are listed below. Fossil species are marked with a dagger "†". * ''Turritella acropora'' (Dall, 1889) * '' Turritella albolapis'' Finlay, 1924 * '' Turritella algida'' Melvill & Standen, 1912 * '' Turritella anactor'' Berry, 1957 * ''Turritella annulata'' Kiener, 1843 * † '' Turritella apicalis'' - Pleistocene of Florida * ''Turritella attenuata'' Reeve, 1849 * '' Turritella aurocincta'' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trigonia
''Trigonia'' is an extinct genus of saltwater clams, fossil marine bivalve mollusk in the family Trigoniidae. The fossil range of the genus spans the Paleozoic, Mesozoic and Paleocene of the Cenozoic, from 298 to 56 Ma. Description The genus ''Trigonia'' is the most readily identifiable member of the family Trigoniidae, having a series of strong ribs or costae along the anterior part of the shell exterior. They are the first representatives of the family to appear in the Middle Triassic (Anisian) of Chile and New Zealand. The first European examples (''Trigonia costata'' Parkinson) appear in the Lower Jurassic (Toarcian) of Sherborne, Dorset and Gundershofen, Switzerland. Species The following ''Trigonia'' species have been described:''Trigonia'' at |
Ostrea
''Ostrea'' is a genus of edible oysters, marine bivalve mollusks in the family Ostreidae, the oysters. Fossil records This genus is very ancient. It is known in the fossil records from the Permian to the Quaternary (age range: from 259 to 0.0 million years ago). Fossil shells of these molluscs can be found all over the world. Genus ''Ostrea'' includes about 150 extinct species. History At least one species within this genus, ''Ostrea lurida'', has been recovered in archaeological excavations along the Central California coast of the Pacific Ocean, demonstrating it was a marine taxon exploited by the Native American Chumash people as a food source. Species Species in the genus ''Ostrea'' include: * † ''Ostrea albertensis'' Russell & Landes, 1937 * ''Ostrea algoensis'' G. B. Sowerby II, 1871 *''Ostrea angasi'' G.B. Sowerby II, 1871 * ''Ostrea angelica'' Rochebrune, 1895 * † ''Ostrea angusta'' Deshayes, 1824 * † ''Ostrea anomialis'' Lamarck, 1819 * † ''Ostrea antarct ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plicatula
Plicatula is a genus of saltwater clams, marine bivalve molluscs, known commonly as kitten's paws or kittenpaws in the family Plicatulidae. MolluscaBase eds. (2022). MolluscaBase. Plicatula Lamarck, 1801. Accessed through: World Register of Marine Species at: https://www.marinespecies.org/aphia.php?p=taxdetails&id=204437 on 2022-01-31 Species * '' Plicatula angolensis'' Cosel, 1995 * '' Plicatula anomioides'' Keen, 1958 * '' Plicatula australis'' Lamarck, 1819 * '' Plicatula ceylanica'' G. B. Sowerby II, 1873 * ''Plicatula complanata'' Deshayes, 1863 * '' Plicatula dubia'' G. B. Sowerby II, 1847 * '' Plicatula gibbosa'' Lamarck, 1801 * '' Plicatula horrida'' Dunker, 1882 * † '' Plicatula hunterae'' Shaak and Nicol, 1974 * † '' Plicatula megaera'' (d'Orbigny, 1850) * '' Plicatula miskito'' Petuch, 1998 * '' Plicatula muricata'' G. B. Sowerby II, 1873 * '' Plicatula novaezelandiae'' G. B. Sowerby II, 1873 * '' Plicatula penicillata'' Carpenter, 1857 * '' Plicatula pernula'' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pecten (bivalve)
''Pecten'' is a genus of large scallops or saltwater clams, marine bivalve molluscs in the family Pectinidae, the scallops. This is the type genus of the family. This genus is known in the fossil record from the Cretaceous period to the Quaternary period (age range: from 70.6 to 0.0 million years ago). Fossil shells within this genus have been found all over the world. Etymology The name ''Pecten'' is from the Latin word for a comb or rake. Since 1904, a ''Pecten'' shell has been used as the basis of the logo of Shell petroleum company. Species Species in the genus ''Pecten'' include: *'' P. albicans'' (Schröter, 1802) *'' P. afribenedictus'' Kilburn & Dijkstra 1995 *'' P. alcesianus'' † McLearn 1933 *'' P. alpha'' † Dall 1898 *'' P. argillensis'' † Conrad 1860 *'' P. assinboiensis'' † Russell & Landes 1937 *'' P. aurantiacus'' Roding 1798 *'' P. aztecus'' † Bose 1906 *'' P. barretti'' † Seeley 1861 *'' P. bifidus'' † Menke 1843 *'' P.biddleana'' †Kell ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lima
Lima ( ; ), originally founded as Ciudad de Los Reyes (City of The Kings) is the capital and the largest city of Peru. It is located in the valleys of the Chillón River, Chillón, Rímac River, Rímac and Lurín Rivers, in the desert zone of the central coastal part of the country, overlooking the Pacific Ocean. Together with the seaside city of Callao, it forms a contiguous urban area known as the Lima Metropolitan Area. With a population of more than 9.7 million in its urban area and more than 10.7 million in its metropolitan area, Lima is one of the largest cities in the Americas. Lima was named by natives in the agricultural region known by native Peruvians as ''Limaq''. It became the capital and most important city in the Viceroyalty of Peru. Following the Peruvian War of Independence, it became the capital of the Republic of Peru (República del Perú). Around one-third of the national population now lives in its Lima Metropolitan Area, metropolitan area. The city of Li ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Continental Shelf
A continental shelf is a portion of a continent that is submerged under an area of relatively shallow water, known as a shelf sea. Much of these shelves were exposed by drops in sea level during glacial periods. The shelf surrounding an island is known as an ''insular shelf''. The continental margin, between the continental shelf and the abyssal plain, comprises a steep continental slope, surrounded by the flatter continental rise, in which sediment from the continent above cascades down the slope and accumulates as a pile of sediment at the base of the slope. Extending as far as 500 km (310 mi) from the slope, it consists of thick sediments deposited by turbidity currents from the shelf and slope. The continental rise's gradient is intermediate between the gradients of the slope and the shelf. Under the United Nations Convention on the Law of the Sea, the name continental shelf was given a legal definition as the stretch of the seabed adjacent to the shores of a par ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Conformably
Lithostratigraphy is a sub-discipline of stratigraphy, the geological science associated with the study of strata or rock layers. Major focuses include geochronology, comparative geology, and petrology. In general, strata are primarily igneous or sedimentary relating to how the rock was formed. Sedimentary layers are laid down by deposition of sediment associated with weathering processes, decaying organic matter (biogenic) or through chemical precipitation. These layers are often distinguishable as having many fossils and are important for the study of biostratigraphy. Igneous layers occur as stacks of lava flows, layers of lava fragments (called tephra) both erupted onto the Earth's surface by volcanoes, and in layered intrusions formed deep underground. Igneous layers are generally devoid of fossils and represent magmatic or volcanic activity that occurred during the geologic history of an area. There are a number of principles that are used to explain the appearance o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
%2C_Guamán_Poma%2C_1616.jpg "Click for more on -> Lima")
