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La Pasada Formation
The La Pasada Formation is a geologic formation in the southern Sangre de Cristo Mountains of New Mexico. It preserves fossils dating back to the early to middle Pennsylvanian. Description The formation is a cyclic carbonate consisting of alternating limestone and shale with some thin sandstones. Total thickness is . The formation is more clastic towards its base (50% shale and siltstone) than towards its upper portion (24% shale and siltstone). The shales are noncalcareous and greenish towards the base but become gray, calcareous, and often fossiliferous towards the upper portion. The formation shows considerable lateral variability, grading into the Flechado Formation to the north. The lower half of the formation is interpreted as a shallow marine nearshore sequence with occasional nonmarine intervals with thin coal beds. The upper half was deposited under neritic offshore marine conditions with infrequent nonmarine intervals. File:Pasada massive bed.jpg, Massive li ... [...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 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 W ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Clastic
Clastic rocks are composed of fragments, or clasts, of pre-existing minerals and rock. A clast is a fragment of geological detritus,Essentials of Geology, 3rd Ed, Stephen Marshak, p. G-3 chunks, and smaller grains of rock broken off other rocks by physical weathering.Essentials of Geology, 3rd Ed, Stephen Marshak, p. G-5 Geologists use the term clastic to refer to sedimentary rocks and particles in sediment transport, whether in suspension or as bed load, and in sediment deposits. Sedimentary clastic rocks Clastic sedimentary rocks are rocks composed predominantly of broken pieces or ''clasts'' of older weathered and eroded rocks. Clastic sediments or sedimentary rocks are classified based on grain size, clast and cementing material (matrix) composition, and texture. The classification factors are often useful in determining a sample's environment of deposition. An example of clastic environment would be a river system in which the full range of grains being transpor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Madera Formation
The Madera Group is a group of geologic formations in northern New Mexico. Its fossil assemblage dates the formation to the middle to late Pennsylvanian period. Description The group consists primarily of marine limestones, and it is exposed in the Sandia Mountains, the Lucero Uplift (), the western Jemez Mountains, the Sangre de Cristo Mountains, and in the Manzano Mountains. The lower section of the group tends to be a gray limestone and the upper an arkosic limestone, and these have been divided into the La Pasada Formation and Alamitos Formation in the southern Sangre de Cristo Mountains. In the Manzano Mountains, the Madera has been divided into the Los Moyos, Wild Cow, and Bursum Formations. Another proposed division in the southeastern Sangre de Cristo Mountains is into the Porvenir and Alamitos Formations. Barry Kues and Katherine Giles have recommended the division of the Madera Group into the Gray Mesa Formation and Atrasado Formation in its western and souther ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ameura
''Ameura'' is an extinct genus of trilobite belonging to the family Proetidae. Fossils from the genus have been found in late Paleozoic The Paleozoic (or Palaeozoic) Era is the earliest of three geologic eras of the Phanerozoic Eon. The name ''Paleozoic'' ( ;) was coined by the British geologist Adam Sedgwick in 1838 by combining the Greek words ''palaiós'' (, "old") and ' ... beds in North America. References Paleozoic arthropods Proetidae Trilobite genera {{Trilobite-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ditomopyge
''Ditomopyge'' is an extinct genus of trilobite belonging to the family Proetidae. It was extant during the Carboniferous and Permian The Permian ( ) is a geologic period and stratigraphic system which spans 47 million years from the end of the Carboniferous Period million years ago (Mya), to the beginning of the Triassic Period 251.9 Mya. It is the last period of the Pale ... and is widely distributed, with fossils found in Europe, southwest Asia, southeast Asia, Australia, North America, and South America. Species *''D. amorni'' Kobayashi and Hamada, 1979 *''D. bjornensis'' Ormiston, 1973 *''D. decurtata'' Gheyselinck, 1937 *''D. dereimsi'' Arellano, 1983 *''D. fatmii'' Grant, 1966 *''D. granulata'' Weber, 1933 *''D. kumpani'' Weber, 1933 *''D. meridionalis'' Teichert, 1944 *''D. ovalis'' Gauri, 1965 *''D. scitula'' Meek and Worthen, 1865 *''D. whitei'' Pabian and Faberstrom, 1972 *''D. yampupatensis'' Arellano, 1983 References Paleozoic life Proetidae Tri ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trilobite
Trilobites (; meaning "three lobes") are extinct marine arthropods that form the class Trilobita. Trilobites form one of the earliest-known groups of arthropods. The first appearance of trilobites in the fossil record defines the base of the Atdabanian stage of the Early Cambrian period () and they flourished throughout the lower Paleozoic before slipping into a long decline, when, during the Devonian, all trilobite orders except the Proetida died out. The last extant trilobites finally disappeared in the mass extinction at the end of the Permian about 252 million years ago. Trilobites were among the most successful of all early animals, existing in oceans for almost 270 million years, with over 22,000 species having been described. By the time trilobites first appeared in the fossil record, they were already highly diversified and geographically dispersed. Because trilobites had wide diversity and an easily fossilized exoskeleton, they left an extensive fossil record. Th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pectinida
Pectinida is a taxonomic order of large and medium-sized saltwater clams, marine bivalve molluscs, commonly known as scallops and their allies. It is believed that they began evolutionarily in the late Middle Ordovician epoch; many species, of course, are still extant. 2010 taxonomy In 2010 a new proposed classification system for the Bivalvia was published by Bieler, Carter & Coan, revising the classification of the Bivalvia, including the order Pectinida.Bieler, R., Carter, J.G. & Coan, E.V. (2010) ''Classification of Bivalve families''. Pp. 113-133, in: Bouchet, P. & Rocroi, J.P. (2010), ''Nomenclator of Bivalve Families. Malacologia'' 52(2): 1-184 *Superfamily: Anomioidea **Family: Anomiidae (jingle shells) **Family: Placunidae (windowpane oysters & saddle oysters) *Superfamily: Plicatuloidea **Family: Plicatulidae (kittenpaws) *Superfamily: Dimyoidea **Family: Dimyidae (dimyidarian oysters) *Superfamily: Pectinoidea **Family: Entoliidae (entoliids) **Family: Pectin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Crinoid
Crinoids are marine animals that make up the Class (biology), class Crinoidea. Crinoids that are attached to the sea bottom by a stalk in their adult form are commonly called sea lilies, while the unstalked forms are called feather stars or comatulids, which are members of the largest crinoid Order (biology), order, Comatulida. Crinoids are Echinoderm, echinoderms in the phylum Echinodermata, which also includes the starfish, brittle stars, sea urchins and sea cucumbers. They live in both shallow water and in depths as great as . Adult crinoids are characterised by having the mouth located on the upper surface. This is surrounded by feeding arms, and is linked to a U-shaped gut, with the anus being located on the oral disc near the mouth. Although the basic echinoderm pattern of fivefold symmetry can be recognised, in most crinoids the five arms are subdivided into ten or more. These have feathery pinnules and are spread wide to gather planktonic particles from the water. At som ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bryozoans
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 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Brachiopods
Brachiopods (), phylum Brachiopoda, are a phylum of trochozoan animals that have hard "valves" (shells) on the upper and lower surfaces, unlike the left and right arrangement in bivalve molluscs. Brachiopod valves are hinged at the rear end, while the front can be opened for feeding or closed for protection. Two major categories are traditionally recognized, articulate and inarticulate brachiopods. The word "articulate" is used to describe the tooth-and-groove structures of the valve-hinge which is present in the articulate group, and absent from the inarticulate group. This is the leading diagnostic skeletal feature, by which the two main groups can be readily distinguished as fossils. Articulate brachiopods have toothed hinges and simple, vertically-oriented opening and closing muscles. Conversely, inarticulate brachiopods have weak, untoothed hinges and a more complex system of vertical and oblique (diagonal) muscles used to keep the two valves aligned. In many brachiopods, a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mesolobus
''Mesolobus'' is an extinct genus of brachiopod belonging to the order Productida and family Rugosochonetidae Rugosochonetidae is an extinct family of brachiopods in the extinct order Productida Productida is an extinct order of brachiopods in the extinct class Strophomenata. Members of Productida first appeared during the Silurian. They represented .... Species *''M. inflata'' Liang, 1990 *''M. striatus'' Weller and McGehee, 1933 References Paleozoic animals Productida {{Brachiopod-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neritic
The neritic zone (or sublittoral zone) is the relatively shallow part of the ocean above the drop-off of the continental shelf, approximately in depth. From the point of view of marine biology it forms a relatively stable and well-illuminated environment for marine life, from plankton up to large fish and corals, while physical oceanography sees it as where the oceanic system interacts with the coast. Definition (marine biology), context, extra terminology In marine biology, the neritic zone, also called coastal waters, the coastal ocean or the sublittoral zone, refers to that zone of the ocean where sunlight reaches the ocean floor, that is, where the water is never so deep as to take it out of the photic zone. It extends from the low tide mark to the edge of the continental shelf, with a relatively shallow depth extending to about 200 meters (660 feet). Above the neritic zone lie the intertidal (or eulittoral) and supralittoral zones; below it the continental slope beg ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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