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Canutillo Formation
The Canutillo Formation is a geologic formation that is exposed in the Franklin Mountains near El Paso, Texas. The formation is Middle Devonian in age. Description The Canutillo Formation consists of about of soft gray siltstone. It is unconformably overlain by the Percha Formation. The Canutillo Formation likely correlates with the Onate Formation. Fossils The formation is fossiliferous, but few fossils are time diagnostic. Fossils include abundant ''Leiorhynchus'' and other brachiopods and a few pelecypods. History of investigation The formation was first described in his dissertation by L.A. Nelson in 1937 for outcrops in the Franklin Mountains. Nelson assigned all beds between the Silurian Fusselman Formation and the Mississippian Helms Formation to the Canutillo. Nelson formally published the definition in 1940 and extended the outcrop range to the Hueco Mountains. In 1945, F.V. Stevenson restricted the formation to the Franklin Mountains. In 1949, Lowell R. Laudon and A ... [...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] |
Onate Formation
The Onate Formation is a geologic formation that is exposed in most of the highlands of south-central New Mexico. It preserves fossils dating back to the middle Devonian period. Description At the type section, the Onate Formation consists of about of orange yellow-weathering dolomitic siltstone with shales and sandstone. Elsewhere the thickness is more typically . The base of the formation is a profound regional unconformity, so that the formation rest on either the Fusselman Formation or the Montoya Group. It is overlain by the Sly Gap Formation and thins to the north and south. The formation is interpreted as having been deposited on a shallow shelf environment deepening to a euxenic basin to the south. Fossils The formation contains the fossil brachiopod ''Spirifer acuminatu'', as well as crinoids and bryozoans. The brachiopod assemblage includes 34 genera and 41 species. Conodonts are rare but a few tabulate corals, ichnofossils, and the receptaculid ''Sphaer ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Paleontology In Texas
Paleontology in Texas refers to paleontological research occurring within or conducted by people from the U.S. state of Texas. Author Marian Murray has remarked that "Texas is as big for fossils as it is for everything else." Some of the most important fossil finds in United States history have come from Texas. Fossils can be found throughout most of the state. The fossil record of Texas spans almost the entire geologic column from Precambrian to Pleistocene. Shark teeth are probably the state's most common fossil. During the early Paleozoic era Texas was covered by a sea that would later be home to creatures like brachiopods, cephalopods, graptolites, and trilobites. Little is known about the state's Devonian and early Carboniferous life. However, evidence indicates that during the late Carboniferous the state was home to marine life, land plants and early reptiles. During the Permian, the seas largely shrank away, but nevertheless coral reefs formed in the state. The rest of Texa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
List Of Fossiliferous Stratigraphic Units In Texas
This article contains a list of fossil-bearing stratigraphic units in the state of Texas, U.S. Sites See also * Paleontology in Texas References * * {{DEFAULTSORT:Fossiliferous stratigraphic units in Texas Fossil Texas Texas (, ; Spanish language, Spanish: ''Texas'', ''Tejas'') is a state in the South Central United States, South Central region of the United States. At 268,596 square miles (695,662 km2), and with more than 29.1 million residents in 2 ... Texas geography-related lists United States geology-related lists Geology of Texas .Stratigraphic units ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hueco Mountains
The Hueco Mountains are a range of mountains that rise in southern Otero County, New Mexico and extend south into Texas, generally along the El Paso– Hudspeth county line just east of the city of El Paso, Texas. The highest point of the range is the Cerro Alto Mountain in Hudspeth County. The Hueco Bolson, a down-dropped area with an elevation of above sea level, with sedimentary fill nearly thick, lies between the Hueco and Franklin Mountains. Shallow, stony soils in the Hueco Mountains support oak, juniper, and some mesquite. The mountains were part of the Rocky Mountain trend, forced upward as part of the Laramide mountain-building period during the late 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 ..., 60 to 70 million years ago. The word ''hueco'' is Sp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Helms Formation
The Helms Formation is a geologic formation in Texas and New Mexico. It preserves fossils dating back to the Chesterian (Serpukhovian) Age of the Carboniferous period. Description At its type section in the Hueco Mountains, the formation consists of of olive-gray shale, shaly sandstone, and dirty limestone. It is unconformably underlain by the Rancheria Formation and unconformably overlain by the La Tuna Formation. The formation also crops out in the Organ Mountains of New Mexico. The formation is interpreted as having been deposited during a marine regression (withdrawal of the sea from the continent) to the south. Fossils The formation contains fossils characteristic of the Chesterian (Serpukhovian) Age of the Carboniferous period. These include abundant specimens of the ostracod ''Graphiadactyllis arkansana'', as well as specimens of the bryozoan ''Archimedes terebriformis'', the echinoderm ''Pentremites'', the brachiopods ''Composita subquadrata'', ''Spiriferina tr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mississippian (geology)
The Mississippian ( , also known as Lower Carboniferous or Early Carboniferous) is a subperiod in the geologic timescale or a subsystem of the geologic record. It is the earlier of two subperiods of the Carboniferous period lasting from roughly 358.9 to 323.2 million years ago. As with most other geochronologic units, the rock beds that define the Mississippian are well identified, but the exact start and end dates are uncertain by a few million years. The Mississippian is so named because rocks with this age are exposed in the Mississippi Valley. The Mississippian was a period of marine transgression in the Northern Hemisphere: the sea level was so high that only the Fennoscandian Shield and the Laurentian Shield were dry land. The cratons were surrounded by extensive delta systems and lagoons, and carbonate sedimentation on the surrounding continental platforms, covered by shallow seas. In North America, where the interval consists primarily of marine limestones, i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Silurian
The Silurian ( ) is a geologic period and system spanning 24.6 million years from the end of the Ordovician Period, at million years ago (Mya), to the beginning of the Devonian Period, Mya. The Silurian is the shortest period of the Paleozoic Era. As with other geologic periods, the rock beds that define the period's start and end are well identified, but the exact dates are uncertain by a few million years. The base of the Silurian is set at a series of major Ordovician–Silurian extinction events when up to 60% of marine genera were wiped out. One important event in this period was the initial establishment of terrestrial life in what is known as the Silurian-Devonian Terrestrial Revolution: vascular plants emerged from more primitive land plants, dikaryan fungi started expanding and diversifying along with glomeromycotan fungi, and three groups of arthropods ( myriapods, arachnids and hexapods) became fully terrestrialized. A significant evolutionary milestone d ... [...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 calc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Brachiopod
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, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Leiorhynchus
''Leiorhynchus'' is an extinct genus of brachiopod belonging to the order Rhynchonellida and family Leiorhynchidae. Specimens have been found in South America, North America, and Russia in beds of middle Devonian to Mississippian Mississippian may refer to: * Mississippian (geology), a subperiod of the Carboniferous period in the geologic timescale, roughly 360 to 325 million years ago *Mississippian culture, a culture of Native American mound-builders from 900 to 1500 AD ... age (372 to 325 million years old). The genus may have been adapted to dysaerobic environments, colonizing areas of reduced oxygen concentrations rich in organic matter. The genus has been used as an index fossil in North America. Species *''L. carboniferum'' *''L. castanea'' Meek 1868 *''L. hippocastanea'' Crickmay 1960 *''L. kelloggi'' Hall 1867 *''L. mesacostale'' Hall 1843 *''L. miriam'' Johnson 1971 *''L. quadracostatus'' Vanuxem 1842 *''L. ripheicus'' Stepanov 1948 *''L. rockymontanum'' Marco ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Unconformity
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 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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