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U-Bar Formation
The U-Bar Formation is a geologic formation in southwestern New Mexico. It preserves fossils dating back to the early Cretaceous period. Description The formation consists mostly of alternating beds of limestone and shale, but with massive upper reef limestone beds (varying from in thickness) and some massive calcarenite beds towards the middle of the formation. Its total thickness is . The massive reef limestones cap ridges that are steep on one side but dip gently on the other. The formation has gradational contacts with both the underlying Hell-to-Finish Formation and the overlying Mojado Formation. Although fossils are abundant, they tend not to be age-specific. However, careful study of the fossils has yielded an age of Aptian to middle Albian. Fossils The lowest beds of the formation contain only small pelecypods, but abundant oyster fossils are found further up in the formation. The alternating shale and limestone beds contain fossil echinoids, the foraminifer ... [...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] |
Reef
A reef is a ridge or shoal of rock, coral or similar relatively stable material, lying beneath the surface of a natural body of water. Many reefs result from natural, abiotic processes— deposition of sand, wave erosion planing down rock outcrops, etc.—but there are also reefs such as the coral reefs of tropical waters formed by biotic processes dominated by corals and coralline algae, and artificial reefs such as shipwrecks and other anthropogenic underwater structures may occur intentionally or as the result of an accident, and sometimes have a designed role in enhancing the physical complexity of featureless sand bottoms, to attract a more diverse assemblage of organisms. Reefs are often quite near to the surface, but not all definitions require this. Earth's largest coral reef system is the Great Barrier Reef in Australia, at a length of over . Biotic There is a variety of biotic reef types, including oyster reefs and sponge reefs, but the most massive and widely ... [...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] |
Bioherm
A reef knoll is a land-based landform that comprises an immense pile of calcareous material that accumulated on a previously existing ancient sea floor. At the time of its accumulation it may have had enough structure from organisms such as sponges to have been free-standing and to withstand the sea currents as material accumulated, and was likely an atoll. Another possibility is the remains of deep water coral. Such structures are thus often fossil-rich. A bioherm is a sedimentary rocky landform enclosed or surrounded by rock of different origin. A biostrome is a distinctly bedded or broadly lenticular sedimentary rocky landform. Krumbein defines these terms as types of stromatolites: "Distinctly bedded, widely extensive, blanketlike build-ups are biostromes. Nodular, biscuit-like, dome-shaped or columnar stromatolites are also referred to as bioherms". England Examples on the Derbyshire/Staffordshire border include Thorpe Cloud and Bunster Hill in southern Dovedale, and also ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lunatia
''Lunatia'' is a genus of predatory sea snails, marine gastropod mollusks in the family Naticidae, the moon snails.Bouchet, P. (2012). Lunatia. Accessed through: World Register of Marine Species at http://www.marinespecies.org/aphia.php?p=taxdetails&id=150577 on 2012-07-12 The species in this genus have been brought in synonymy mostly with ''Euspira'' Torigoe & Inaba (2011) provided a rather arbitrary assignment of species to respectively ''Euspira'' and ''Lunatia'' and this has been at one time uploaded in the WoRMS classification. However this is not based on any in-depth phylogenetic analysis and has proved inconsistent when some closely related European species (e.g. Euspira guillemini, E. macilenta) were then not congeneric. Until a substantiated phylogenetic hypothesis is published for the group, ''Lunatia'' is here considered a junior subjective synonym of ''Euspira'' and all the species accepted under ''Euspira'', following in this Marincowich (1977), Kabat (1991) and t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gastropod
The gastropods (), commonly known as snails and slugs, belong to a large taxonomic class of invertebrates within the phylum Mollusca called Gastropoda (). This class comprises snails and slugs from saltwater, from freshwater, and from land. There are many thousands of species of sea snails and slugs, as well as freshwater snails, freshwater limpets, and land snails and slugs. The class Gastropoda contains a vast total of named species, second only to the insects in overall number. The fossil history of this class goes back to the Late Cambrian. , 721 families of gastropods are known, of which 245 are extinct and appear only in the fossil record, while 476 are currently extant with or without a fossil record. Gastropoda (previously known as univalves and sometimes spelled "Gasteropoda") are a major part of the phylum Mollusca, and are the most highly diversified class in the phylum, with 65,000 to 80,000 living snail and slug species. The anatomy, behavior, feeding, and re ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Orbitolina
''Orbitolina'' is an extinct genus of foraminifera belonging to the order Textulariida and family Orbitolinidae. Fossils of this genus are widely found in beds deposited in the Tethys Ocean ranging from Aptian (early Cretaceous)) to Cenomanian (early Late Cretaceous) in age. It has been used as a shallow carbonate platform facies In geology, a facies ( , ; same pronunciation and spelling in the plural) is a body of rock with specified characteristics, which can be any observable attribute of rocks (such as their overall appearance, composition, or condition of formatio ... marker and as a Cretaceous index fossil. The test of the organism has the shape of a cone, with the proloculus (initial chamber) at the apex of the cone and increasingly large cuplike chambers forming the remainder of the test. Each chamber is further subdivided by numerous partitions. References Globothalamea {{Foraminifera-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Foraminifer
Foraminifera (; Latin for "hole bearers"; informally called "forams") are single-celled organisms, members of a phylum or class of amoeboid protists characterized by streaming granular ectoplasm for catching food and other uses; and commonly an external shell (called a "test") of diverse forms and materials. Tests of chitin (found in some simple genera, and Textularia in particular) are believed to be the most primitive type. Most foraminifera are marine, the majority of which live on or within the seafloor sediment (i.e., are benthic), while a smaller number float in the water column at various depths (i.e., are planktonic), which belong to the suborder Globigerinina. Fewer are known from freshwater or brackish conditions, and some very few (nonaquatic) soil species have been identified through molecular analysis of small subunit ribosomal DNA. Foraminifera typically produce a test, or shell, which can have either one or multiple chambers, some becoming quite elaborate in struc ... [...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] |
Pelecypod
Bivalvia (), in previous centuries referred to as the Lamellibranchiata and Pelecypoda, is a class of marine and freshwater molluscs that have laterally compressed bodies enclosed by a shell consisting of two hinged parts. As a group, bivalves have no head and they lack some usual molluscan organs, like the radula and the odontophore. They include the clams, oysters, cockles, mussels, scallops, and numerous other families that live in saltwater, as well as a number of families that live in freshwater. The majority are filter feeders. The gills have evolved into ctenidia, specialised organs for feeding and breathing. Most bivalves bury themselves in sediment, where they are relatively safe from predation. Others lie on the sea floor or attach themselves to rocks or other hard surfaces. Some bivalves, such as the scallops and file shells, can swim. The shipworms bore into wood, clay, or stone and live inside these substances. The shell of a bivalve is composed of ca ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Albian
The Albian is both an age of the geologic timescale and a stage in the stratigraphic column. It is the youngest or uppermost subdivision of the Early/Lower Cretaceous Epoch/Series. Its approximate time range is 113.0 ± 1.0 Ma to 100.5 ± 0.9 Ma (million years ago). The Albian is preceded by the Aptian and followed by the Cenomanian. Stratigraphic definitions The Albian Stage was first proposed in 1842 by Alcide d'Orbigny. It was named after Alba, the Latin name for River Aube in France. A Global Boundary Stratotype Section and Point (GSSP), ratified by the IUGS in 2016, defines the base of the Albian as the first occurrence of the planktonic foraminiferan '' Microhedbergella renilaevis'' at the Col de Pré-Guittard section, Arnayon, Drôme, France. The top of the Albian Stage (the base of the Cenomanian Stage and Upper Cretaceous Series) is defined as the place where the foram species '' Rotalipora globotruncanoides'' first appears in the stratigraphic column. The Albia ... [...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] |
