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Zia Formation
The Zia Formation is a geologic formation in the southwestern Jemez Mountains and northwestern Santo Domingo basin. It contains vertebrate fossils that date it to early to middle Miocene in age. Description The Zia Formation is a very soft quartz sandstone. The type section rests on about of laminated greenish clay beds that in turn rest on the Galisteo Formation. The upper contact is with the Cerro Conejo Formation, with the Cochiti Formation, or with Miocene volcanic rocks of the Jemez volcanic field. The formation is divided (in ascending stratigraphic order) into the Piedra Parada Member, the Chamisa Mesa Member. and the Canada Pilares Member. The formation is interpreted as eolian deposits derived from volcaniclastics of the Jemez volcanic field. These were first transported south by the Jemez River, then transported by wind from the west. Fossils The Piera Parada Member contains fossils mostly of camels (''Stenomylus'', '' Oxydactylus'', and ''Michenia'') and ... [...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] |
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] |
Arikareean
The Arikareean North American Stage on the geologic timescale is the North American faunal stage according to the North American Land Mammal Ages chronology (NALMA), typically set from 30,600,000 to 20,800,000 years BP, a period of . It is usually considered to overlap the Oligocene and Miocene epochs. The Arikareean is preceded by the Whitneyan and followed by the Hemingfordian NALMA stages. The Arikareean can be further divided into the substages of: *late Late Arikareean: Lower boundary source, base of Geringian The Geringian North American Stage on the geologic timescale is the North American faunal stage according to the North American Land Mammal Ages chronology (NALMA), typically set from 30,800,000 to 26,300,000 years BP, a period of . It is usual ... (approximate) *early Late Arikareean: base of Geringian (approximate). Upper boundary source: base of Hemingfordian (approximate). *late Early Arikareean: Lower boundary source of base of Geringian (approximate). Upper ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Diceratherium
''Diceratherium'' (meaning "two horned beast") is an extinct genus of rhinoceros endemic to North America, Europe, and Asia during the Oligocene through Miocene living from 33.9 to 11.6 mya, existing for approximately . Mass estimates for the type species, ''D. armatum'' average around Taxonomy ''Diceratherium'' was named by Marsh (1875). It is not extant. Its type is ''Diceratherium armatum''. It was assigned to Rhinocerotidae by Marsh (1875) and Carroll (1988); to Diceratheriinae by Prothero (1998); to Aceratheriinae by Weidmann and Ginsburg (1999); and to Teleoceratini by Sach and Heizmann (2001).V. J. Sach and E. P. J. Heizmann. 2001. Stratigraphy and mammal faunas of the Brackwassermolasse in the surroundings of Ulm (Southwest Germany). Stuttgarter Beiträge zur Naturkunde, Serie B (Geologie und Paläontologie) 310:1-95 ''Diceratherium'' had two horns side by side on its nose. It lived during the Miocene Epoch The Miocene ( ) is the first geological epoch of t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Michenia
''Michenia'' is an extinct genus of camelid endemic to North America. They lived from the Early Miocene to Middle Miocene 20.43—10.3 mya, existing for approximately . Fossil have been found from California to Texas, Alberta, Idaho and Nebraska Nebraska () is a state in the Midwestern region of the United States. It is bordered by South Dakota to the north; Iowa to the east and Missouri to the southeast, both across the Missouri River; Kansas to the south; Colorado to the southwe .... Species *''M. agatensis'' Frick & Taylor 1971 *''M. deschutensis'' Dingus 1990 *''M. exilis'' Matthew & Macdonald 1960 *''M. mudhillsnsis'' Pagnac 2005 References Prehistoric camelids Prehistoric even-toed ungulate genera Oligocene even-toed ungulates Pliocene even-toed ungulates Miocene even-toed ungulates Zanclean extinctions Prehistoric mammals of North America Fossil taxa described in 1971 {{paleo-eventoedungulate-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oxydactylus
''Oxydactylus'' is an extinct genus of camelid endemic to North America. It lived from the Late Oligocene to the Middle Miocene (28.4–13.7 mya), existing for approximately . The name is from the Ancient Greek οξύς (oxys, "sharp")and δάκτυλος (daktylos, "finger"). They had very long legs and necks, and were probably adapted to eating high vegetation, much like modern giraffes The giraffe is a large African hoofed mammal belonging to the genus ''Giraffa''. It is the tallest living terrestrial animal and the largest ruminant on Earth. Traditionally, giraffes were thought to be one species, ''Giraffa camelopardalis .... Unlike modern camelids, they had hooves, rather than tough sole-pads, and splayed toes. References Prehistoric camelids Oligocene even-toed ungulates Miocene even-toed ungulates Serravallian genus extinctions Miocene mammals of North America Oligocene mammals of North America Prehistoric even-toed ungulate genera Chattian gen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stenomylus
''Stenomylus'' is an extinct genus of miniature camelid native to North America that died out around 30 million years ago. Its name is derived from the Greek (, "narrow") and (, "molar"). ''Stenomylus'' was extremely diminutive compared to other ancient and modern camelids, standing only tall on average. It was a slender animal with a long neck, having some resemblance to a modern gazelle. Unlike modern camelids, ''Stenomylus'' lacked padding on its hooves and based on theories about its biomechanics. Description Although a member of the Camelidae, the gracile ''Stenomylus'' looked very similar to today's gazelles. The legs, in fact, were extremely elongated and bore only two toes; the legs had separate metacarpal but some species showed an incipient fusing of metacarpals, especially in the metatarsus. The nail phalanges suggest the presence of hooves similar to those of deer, and not of fleshy pads like those of today's camels. [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jemez River
The Jemez River is a tributary of the Rio Grande in eastern Sandoval County, New Mexico, United States. Description The river is formed by the confluence of the East Fork Jemez River and San Antonio Creek, which drain a number of tributaries in the area of the Jemez Mountains and Santa Fe National Forest. The Jemez River is about long, or about long if its longest headwater tributary, San Antonio Creek, is included. The East Fork Jemez River is about long. Both San Antonio Creek and the East Fork Jemez River flow through intricate meanders along their courses.Lengths calculated in Google Earth The East Fork Jemez is a National Wild and Scenic River. The Jemez River flows generally south to join the Rio Grande near Bernalillo, north of Albuquerque.General course info from USGS topographic maps Course The main tributaries streams that join to form the Jemez River are San Antonio Creek and the East Fork Jemez River. Both originate on the west side of the Sierra de los Valle ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Volcaniclastic
Volcaniclastics are geologic materials composed of broken fragments (clasts) of volcanic rock. These encompass all clastic volcanic materials, regardless of what process fragmented the rock, how it was subsequently transported, what environment it was deposited in, or whether nonvolcanic material is mingled with the volcanic clasts. The United States Geological Survey defines volcaniclastics somewhat more narrowly, to include only rock composed of volcanic rock fragments that have been transported some distance from their place of origin. In the broad sense of the term, volcaniclastics includes pyroclastic rocks such as the Bandelier Tuff; cinder cones and other tephra deposits; the basal and capping breccia that characterize ʻaʻā lava flows; and lahars and debris flows of volcanic origin.Vincent 2000, pp.27-28 Volcaniclastics make up more of the volume of many volcanoes than do lava flows. Volcaniclastics may have contributed as much as a third of all sedimentation in the geolo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aeolian Processes
Aeolian processes, also spelled eolian, pertain to wind activity in the study of geology and weather and specifically to the wind's ability to shape the surface of the Earth (or other planets). Winds may erode, transport, and deposit materials and are effective agents in regions with sparse vegetation, a lack of soil moisture and a large supply of unconsolidated sediments. Although water is a much more powerful eroding force than wind, aeolian processes are important in arid environments such as deserts. The term is derived from the name of the Greek god Aeolus, the keeper of the winds. Definition and setting ''Aeolian processes'' are those processes of erosion, transport, and deposition of sediments that are caused by wind at or near the surface of the earth. Sediment deposits produced by the action of wind and the sedimentary structures characteristic of these deposits are also described as ''aeolian''. Aeolian processes are most important in areas where there is little or ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Member (stratigraphy)
A stratigraphic unit is a volume of rock of identifiable origin and relative age range that is defined by the distinctive and dominant, easily mapped and recognizable petrographic, lithologic or paleontologic features (facies) that characterize it. Units must be ''mappable'' and ''distinct'' from one another, but the contact need not be particularly distinct. For instance, a unit may be defined by terms such as "when the sandstone component exceeds 75%". Lithostratigraphic units Sequences of sedimentary and volcanic rocks are subdivided the basis of their shared or associated lithology. Formally identified lithostratigraphic units are structured in a hierarchy of lithostratigraphic rank, higher rank units generally comprising two or more units of lower rank. Going from smaller to larger in rank, the main lithostratigraphic ranks are Bed, Member, Formation, Group and Supergroup. Formal names of lithostratigraphic units are assigned by geological surveys. Units of formation or hi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stratigraphic
Stratigraphy is a branch of geology concerned with the study of rock layers (strata) and layering (stratification). It is primarily used in the study of sedimentary and layered volcanic rocks. Stratigraphy has three related subfields: lithostratigraphy (lithologic stratigraphy), biostratigraphy (biologic stratigraphy), and chronostratigraphy (stratigraphy by age). Historical development Catholic priest Nicholas Steno established the theoretical basis for stratigraphy when he introduced the law of superposition, the principle of original horizontality and the principle of lateral continuity in a 1669 work on the fossilization of organic remains in layers of sediment. The first practical large-scale application of stratigraphy was by William Smith in the 1790s and early 19th century. Known as the "Father of English geology", Smith recognized the significance of strata or rock layering and the importance of fossil markers for correlating strata; he created the first geologic map o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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