|
Trincheras Formation
The Trincheras Formation ( es, Formación Trincheras, Kitr) is a geological formation of the Altiplano Cundiboyacense, Eastern Ranges of the Colombian Andes. The formation consisting of a lower unit of calcareous shales and an upper sequence of shales dates to the Early Cretaceous period; Early Aptian epoch and has a maximum thickness of . The formation, deposited in a marine platform environment, part of a transgressive cycle, hosts ammonite, bryozoan, mollusc and echinoid fossils. Etymology The formation was defined and named in 1969 by Cáceres and Etayo after Quebrada Trincheras, Apulo, Cundinamarca.Acosta & Ulloa, 2002, p.39 Description Lithologies The Trincheras Formation has a maximum thickness of ,Acosta & Ulloa, 2001, p.23 and is characterised by a sequence of claystones with intercalated limestones and sandstones. Fossils of the ammonites '' Heinzia sp.'', '' Pseudohaploceras sp.'', '' Heminautilus etheringtoni'', '' Cheloniceras sp.'' and bryozoans, mollu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aptian
The Aptian is an age in the geologic timescale or a stage in the stratigraphic column. It is a subdivision of the Early or Lower Cretaceous Epoch or Series and encompasses the time from 121.4 ± 1.0 Ma to 113.0 ± 1.0 Ma (million years ago), approximately. The Aptian succeeds the Barremian and precedes the Albian, all part of the Lower/Early Cretaceous. The Aptian partly overlaps the upper part of the Western European Urgonian Stage. The Selli Event, also known as OAE1a, was one of two oceanic anoxic events in the Cretaceous Period, which occurred around 120 Ma and lasted approximately 1 to 1.3 million years. The Aptian extinction was a minor extinction event hypothesized to have occurred around 116 to 117 Ma.Archangelsky, Sergio.The Ticó Flora (Patagonia) and the Aptian Extinction Event" ''Acta Paleobotanica'' 41(2), 2001, pp. 115-22. Stratigraphic definitions The Aptian was named after the small city of Apt in the Provence region of France, which is also known for its cry ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Formation (geology)
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] |
List Of Fossiliferous Stratigraphic Units Of Colombia
Several stratigraphic units in Colombia have provided fossils. The richest formations are the Devonian Cuche Formation, Cuche and Floresta Formations, the Cretaceous Paja Formation, the Paleocene Cerrejón Formation and the Miocene La Venta (Colombia), La Venta site. The latter is the richest Lagerstätte, Konzentrat-Lagerstätte in northern South America and comprises the formations of the Honda Group, Colombia, Honda Group. __TOC__ Fossiliferous stratigraphic units ''Formations are ordered according to their youngest age'' Proposed reclassification of South American gomphotheres Some authors, Spencer G. Lucas, Lucas, Mothé, Avilla et al., propose a reclassification of the South American gomphotheres as follows:Lucas, 2013Mothé et al., 2012Mothé et al., 2016aMothé et al., 2016b * ''Stegomastodon'' is an exclusively North American genus * ''Haplomastodon'' is a South American genus, but synonymous with ''Notiomastodon'' * as ''Notiomastodon'' was Principle of Prio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Heminautilus
''Heminautilus'' is an extinct genus of nautiloids from the nautilacean family Cenoceratidae that lived during the Early Cretaceous. Fossils of ''Heminautilus'' have been registered in rocks of Barremian and Aptian age.''Heminautilus'' at Fossilworks.org Nautiloids
Nautiloids are a group of marine cephalopods (Mollusca) which originated in the Late Cambrian and are represented today by the living ''Nautilus'' and ''Allonautilus''. Fossil nautiloids are diverse and speciose, with over 2,500 recorded species ... are a subclass of shelled [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pseudohaploceras
''Pseudohaploceras'' is a genus of desmosceratid ammonites from the Early Cretaceous; Valanginian to Albian epochs. with and (1996), ''Mollusca 4 Revised , Cretaceous Ammonoidea'', vol. 4, in ''Treatise on Invertebrate Paleontology'', Part L (Roger L. Kaesler ed.), Boulder, Colorado: The Geological Society of America & Lawrence, Kansas: University of Kansas Press, pp. 73, 72. Description The genus is distinguished by its moderately involute, slightly to moderately compressed shell with convex sides and regular straight or sinuous constrictions between which are fairly fine, distinct, sharp or rounded branching ribs extending from the umbilical edge and crossing the venter, the outer rim. ''Pseudohaploceras'' is considered an offshoot of early '' Valdedorsella'', which differ in having a more broadly rounded whorl section and generally straight radial constrictions. It is included in the subfamily Pizosiinae. Distribution Fossils of ''Pseudohaploceras'' have been ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Heinzia
''Heinzia'' is an extinct ammonoid cephalopod genus belonging to the family Pulchelliidae. They lived during the Cretaceous, in the Barremian age. Distribution Fossils of species within this genus have been found in 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 ... sediments of Colombia, France, Italy, Morocco and Spain. References Crioceratites* Jean VermeulenOrigine, classification et évolution des Pulchellinae (Douville) 1911 emend. Vermeulen 1995 (Pulchelliidae, Endemoceratoidea)* C. W. Wright, J. H. Calloman and M. K. Howarth, 199Treatise on invertebrate paleontology, volume 4 : cretaceous ammonoidea* Vermeulen, Jean., 1995A new division in three parts of the Pulchelliidae family AmmonoideaRiviera Scientifique, 65-80 Ammonitida genera Endemoceratoide ... [...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] |
Claystone
Mudrocks are a class of fine-grained siliciclastic sedimentary rocks. The varying types of mudrocks include siltstone, claystone, mudstone, slate, and shale. Most of the particles of which the stone is composed are less than and are too small to study readily in the field. At first sight, the rock types appear quite similar; however, there are important differences in composition and nomenclature. There has been a great deal of disagreement involving the classification of mudrocks. A few important hurdles to their classification include the following: # Mudrocks are the least understood and among the most understudied sedimentary rocks to date. # Studying mudrock constituents is difficult due to their diminutive size and susceptibility to weathering on outcrops. # And most importantly, scientists accept more than one classification scheme. Mudrocks make up 50% of the sedimentary rocks in the geologic record and are easily the most widespread deposits on Earth. Fine sedimen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Echinoid
Sea urchins () are spine (zoology), spiny, globular echinoderms in the class Echinoidea. About 950 species of sea urchin live on the seabed of every ocean and inhabit every depth zone from the intertidal seashore down to . The spherical, hard shells (Test (biology), tests) of sea urchins are round and spiny, ranging in diameter from . Sea urchins move slowly, crawling with tube feet, and also propel themselves with their spines. Although algae are the primary diet, sea urchins also eat slow-moving (Sessility (motility), sessile) animals. Predation, Predators that eat sea urchins include a wide variety of fish, starfish, crabs, marine mammals. Sea urchins are also used as food especially in Japan. Adult sea urchins have fivefold symmetry, but their pluteus larvae feature Bilateral symmetry, bilateral (mirror) symmetry, indicating that the sea urchin belongs to the Bilateria group of animal phylum, phyla, which also comprises the chordates and the arthropods, the annelids and the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mollusc
Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda, the members of which are known as molluscs or mollusks (). Around 85,000 extant species of molluscs are recognized. The number of fossil species is estimated between 60,000 and 100,000 additional species. The proportion of undescribed species is very high. Many taxa remain poorly studied. Molluscs are the largest marine phylum, comprising about 23% of all the named marine organisms. Numerous molluscs also live in freshwater and terrestrial habitats. They are highly diverse, not just in size and anatomical structure, but also in behaviour and habitat. The phylum is typically divided into 7 or 8 taxonomic classes, of which two are entirely extinct. Cephalopod molluscs, such as squid, cuttlefish, and octopuses, are among the most neurologically advanced of all invertebrates—and either the giant squid or the colossal squid is the largest known invertebrate species. The gastropods ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bryozoa
Bryozoa (also known as the Polyzoa, Ectoprocta or commonly as moss animals) are a phylum of simple, aquatic invertebrate animals, nearly all living in sedentary colonies. Typically about long, they have a special feeding structure called a lophophore, a "crown" of tentacles used for filter feeding. Most marine bryozoans live in tropical waters, but a few are found in oceanic trenches and polar waters. The bryozoans are classified as the marine bryozoans (Stenolaemata), freshwater bryozoans (Phylactolaemata), and mostly-marine bryozoans (Gymnolaemata), a few members of which prefer brackish water. 5,869living species are known. At least two genera are solitary (''Aethozooides'' and ''Monobryozoon''); the rest are colonial. The terms Polyzoa and Bryozoa were introduced in 1830 and 1831, respectively. Soon after it was named, another group of animals was discovered whose filtering mechanism looked similar, so it was included in Bryozoa until 1869, when the two groups were no ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Saunders_Quarry-1.jpg "Click for more on -> Sandstone")
