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Porvenir Formation
The Porvenir Formation is a geologic formation exposed in the southeastern Sangre de Cristo Mountains of New Mexico. It preserves fossils dating back to the middle Pennsylvanian period. Description The formation is mostly marine and can be divided into three intergrading facies. The first, located primarily to the south, is mostly limestone with some interbedded shale and sandstone. The second facies, located to the north and northwest, is mostly gray shale with some thick limestone and thin sandstone beds. The third facies, found to the northeast, is mostly shale, limestone (including sandy and oolitic limestone) and arkosic sandstone. Thickness is . The formation rests conformably on the Sandia Formation and is disconformably overlain by the Alamitos Formation. Fossils The formation contains fusulinids of Desmoinesian ( Moscovian) age. History of investigation The formation was first named by Baltz and Myers in 1984, who considered it correlative with the lower part of the ... [...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] |
Limestone
Limestone ( calcium carbonate ) is a type of carbonate sedimentary rock which is the main source of the material lime. It is composed mostly of the minerals calcite and aragonite, which are different crystal forms of . Limestone forms when these minerals precipitate out of water containing dissolved calcium. This can take place through both biological and nonbiological processes, though biological processes, such as the accumulation of corals and shells in the sea, have likely been more important for the last 540 million years. Limestone often contains fossils which provide scientists with information on ancient environments and on the evolution of life. About 20% to 25% of sedimentary rock is carbonate rock, and most of this is limestone. The remaining carbonate rock is mostly dolomite, a closely related rock, which contains a high percentage of the mineral dolomite, . ''Magnesian limestone'' is an obsolete and poorly-defined term used variously for dolomite, for limes ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Paleontology In New Mexico
Paleontology in New Mexico refers to paleontological research occurring within or conducted by people from the U.S. state of New Mexico. The fossil record of New Mexico is exceptionally complete and spans almost the entire stratigraphic column. More than 3,300 different kinds of fossil organisms have been found in the state. Of these more than 700 of these were new to science and more than 100 of those were type species for new genera. During the early Paleozoic, southern and western New Mexico were submerged by a warm shallow sea that would come to be home to creatures including brachiopods, bryozoans, cartilaginous fishes, corals, graptolites, nautiloids, placoderms, and trilobites. During the Ordovician the state was home to algal reefs up to 300 feet high. During the Carboniferous, a richly vegetated island chain emerged from the local sea. Coral reefs formed in the state's seas while terrestrial regions of the state dried and were home to sand dunes. Local wildlife includ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
List Of Fossiliferous Stratigraphic Units In New Mexico
This article contains a list of fossil-bearing stratigraphic units in the state of New Mexico, U.S. Sites See also * Paleontology in New Mexico References * {{DEFAULTSORT:Fossiliferous stratigraphic units in New Mexico New Mexico Stratigraphic units A stratigraphic unit is a volume of Rock (geology), rock of identifiable origin and relative age range that is defined by the distinctive and dominant, easily mapped and recognizable petrology, petrographic, lithology, lithologic or paleontology, p ... Stratigraphy of New Mexico New Mexico geography-related lists United States geology-related lists ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spencer G
Spencer may refer to: People *Spencer (surname) **Spencer family, British aristocratic family ** List of people with surname Spencer * Spencer (given name), a given name (including a list of people with the name) Places Australia *Spencer, New South Wales, on the Central Coast *Spencer Gulf, one of two inlets on the South Australian coast United States *Spencer, Idaho *Spencer, Indiana *Spencer, Iowa *Spencer, Massachusetts **Spencer (CDP), Massachusetts *Spencer, Missouri *Spencer, Nebraska *Spencer, New York **Spencer (village), New York *Spencer, North Carolina *Spencer, Ohio *Spencer, Oklahoma *Spencer, South Dakota *Spencer, Tennessee *Spencer, Virginia *Spencer, West Virginia *Spencer, Wisconsin **Spencer (town), Wisconsin *Spencer County, Indiana *Spencer County, Kentucky Ireland *Spencer Dock, North Wall, Dublin Arts and entertainment Fictional characters *Spencer, character in ''Beyblade'' *Spencer, character from ''Final Fantasy Mystic Quest'' * Spencer family (''G ... [...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 southern ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Moscovian (Carboniferous)
The Moscovian is in the International Commission on Stratigraphy, ICS geologic timescale a stage (stratigraphy), stage or age (geology), age in the Pennsylvanian (geology), Pennsylvanian, the youngest system (stratigraphy), subsystem of the Carboniferous. The Moscovian age lasted from to Megaannum, Ma, is preceded by the Bashkirian and is followed by the Kasimovian. The Moscovian overlaps with the European regional Westphalian (stage), Westphalian stage and the North American Atokan and Desmoinesian stages. Name and definition The Moscovian Stage was introduced by Sergei Nikitin (geologist), Sergei Nikitin (1850 - 1909) in 1890, using brachiopods in the Moscow Basin of European Russia. Nikitin named the stage after Moscow, then a major city and now the capital of Russia. The base of the Moscovian is close to the first appearances of the conodonts ''Declinognathodus donetzianus'' and ''Idiognathoides postsulcatus'' or otherwise the fusulinid ''Aljutovella aljutovica''. Because th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fusulinid
The Fusulinida is an extinct order within the Foraminifera in which the tests are traditionally considered to have been composed of microgranular calcite. Like all forams, they were single-celled organisms. In advanced forms the test wall was differentiated into two or more layers. Loeblich and Tappan, 1988, gives a range from the Lower Silurian to the Upper Permian, with the fusulinid foraminifera going extinct with the Permian–Triassic extinction event. While the latter is true, a more supported projected timespan is from the Mid-Carboniferous period. Taxonomy Thirteen superfamilies are presently recognised, based on taxa (families) included in the three superfamilies given in the Treatise. Three are based on families in the Parathuramminacea, 1964, and 2.9 million families in the Endothyracea, 1964. The Fusulinacea remains the same in both sources (Treatise 1964 and Loeblich and Tappan, 1988). The term fusulinata has traditionally been used to refer to all palaeozoic for ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Disconformity (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 is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arkose
Arkose () or arkosic sandstone is a detrital sedimentary rock, specifically a type of sandstone containing at least 25% feldspar. Arkosic sand is sand that is similarly rich in feldspar, and thus the potential precursor of arkose. Quartz is commonly the dominant mineral component, and some mica is often present. Apart from the mineral content, rock fragments may also be a significant component. Arkose usually contains small amounts of calcite cement, which causes it to effervesce (fizz) slightly in dilute hydrochloric acid; sometimes the cement also contains iron oxide. Arkose is typically grey to reddish in colour. The sand grains making up an arkose may range from fine to very coarse, but tend toward the coarser end of the scale. Fossils are rare in arkose, due to the depositional processes that form it, although bedding is frequently visible. Arkose is generally formed from the weathering of feldspar-rich igneous or metamorphic, most commonly granitic, rocks, which are p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oolitic Limestone
Oolite or oölite (''egg stone'') is a sedimentary rock formed from ooids, spherical grains composed of concentric layers. The name derives from the Ancient Greek word for egg (ᾠόν). Strictly, oolites consist of ooids of diameter 0.25–2 millimetres; rocks composed of ooids larger than 2 mm are called pisolites. The term ''oolith'' can refer to oolite or individual ooids. Composition Ooids are most commonly composed of calcium carbonate (calcite or aragonite), but can be composed of phosphate, clays, chert, dolomite or iron minerals, including hematite. Dolomitic and chert ooids are most likely the result of the replacement of the original texture in limestone. Oolitic hematite occurs at Red Mountain near Birmingham, Alabama, along with oolitic limestone. They are usually formed in warm, supersaturated, shallow, highly agitated marine water intertidal environments, though some are formed in inland lakes. The mechanism of formation starts with a small fragment of se ... [...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] |
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