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Unkar Group
The Unkar Group is a sequence of strata of Proterozoic age that are subdivided into five geologic formations and exposed within the Grand Canyon, Arizona, Southwestern United States. The 5-unit Unkar Group is the basal member of the 8-member Grand Canyon Supergroup. The Unkar is about thick and composed, in ascending order, of the Bass Formation, Hakatai Shale, Shinumo Quartzite, Dox Formation, and Cardenas Basalt. Units 4 & 5 are found mostly in the eastern region of Grand Canyon. Units 1 through 3 are found in central Grand Canyon. The Unkar Group accumulated approximately between 1250 and 1104 Ma (1,104 million years ago, 1.1 billion). In ascending order, the Unkar Group is overlain by the Nankoweap Formation, about thick; the Chuar Group, about thick; and the Sixtymile Formation, about thick. These are all of the units of the Grand Canyon Supergroup.Hendricks, JD, and GM Stevenson (2003) ''Grand Canyon Supergroup: Unkar Group.'' In SS Beus and M Morales, eds., ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dox Formation
The Dox Formation, also known as the Dox Sandstone, is a Mesoproterozoic rock formation that outcrops in the eastern Grand Canyon, Coconino County, Arizona. The strata of the Dox Formation, except for some more resistant sandstone beds, are relatively susceptible to erosion and weathering. The lower member of the Dox Formation consists of silty-sandstone and sandstone, and some interbedded argillaceous beds, that form stair-stepped, cliff-slope topography. The bulk of the Dox Formation typically forms rounded and sloping hill topography that occupies an unusually broad section of the canyon.Hendricks, JD, and GM Stevenson (2003) ''Grand Canyon Supergroup: Unkar Group.'' In SS Beus and M Morales, eds., pp. 39–52, Grand Canyon Geology, 2nd ed. Oxford University Press, New York. The Dox Formation comprises the bulk of the Unkar Group, the base section of the Grand Canyon Supergroup. The Unkar Group is about thick and composed of, in ascending order, the Bass Formation, Hakat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vishnu Basement Rocks
The Vishnu Basement Rocks is the name recommended for all Early Proterozoic crystalline rocks (metamorphic and igneous) exposed in the Grand Canyon region. They form the crystalline basement rocks that underlie the Bass Limestone of the Unkar Group of the Grand Canyon Supergroup and the Tapeats Sandstone of the Tonto Group. These basement rocks have also been called either the Vishnu Complex or Vishnu Metamorphic Complex. These Early Proterozoic crystalline rocks consist of metamorphic rocks that are collectively known as the ''Granite Gorge Metamorphic Suite''; sections of the Vishnu Basement Rocks contain Early Paleoproterozoic granite, granitic pegmatite, aplite, and granodiorite that have intruded these metamorphic rocks, and also, intrusive Early Paleoproterozoic ultramafic rocks.Anonymous (nd''Vishnu Basement Rocks.''U. S. Geological Survey, Reston, Virginia.Karlstrom, KE, BR Ilg, Bradley, D Hawkins, ML Williams, G Dumond, KK. Mahan, and SA Bowring, Samuel (2012) ''Vishnu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fault Block
Fault blocks are very large blocks of rock, sometimes hundreds of kilometres in extent, created by tectonic and localized stresses in Earth's crust. Large areas of bedrock are broken up into blocks by faults. Blocks are characterized by relatively uniform lithology. The largest of these fault blocks are called crustal blocks. Large crustal blocks broken off from tectonic plates are called terranes. Those terranes which are the full thickness of the lithosphere are called microplates. Continent-sized blocks are called variously ''microcontinents, continental ribbons, H-blocks, extensional allochthons and outer highs.'' Because most stresses relate to the tectonic activity of moving plates, most motion between blocks is horizontal, that is parallel to the Earth's crust by strike-slip faults. However vertical movement of blocks produces much more dramatic results. Landforms (mountains, hills, ridges, lakes, valleys, etc.) are sometimes formed when the faults have a large v ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fault (geology)
In geology, a fault is a planar fracture or discontinuity in a volume of rock across which there has been significant displacement as a result of rock-mass movements. Large faults within Earth's crust result from the action of plate tectonic forces, with the largest forming the boundaries between the plates, such as the megathrust faults of subduction zones or transform faults. Energy release associated with rapid movement on active faults is the cause of most earthquakes. Faults may also displace slowly, by aseismic creep. A ''fault plane'' is the plane that represents the fracture surface of a fault. A ''fault trace'' or ''fault line'' is a place where the fault can be seen or mapped on the surface. A fault trace is also the line commonly plotted on geologic maps to represent a fault. A ''fault zone'' is a cluster of parallel faults. However, the term is also used for the zone of crushed rock along a single fault. Prolonged motion along closely spaced faults can blur the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sixtymile Formation
The Sixtymile Formation is a very thin accumulation of sandstone, siltstone, and breccia underlying the Tapeats Sandstone that is exposed in only four places in the Chuar Valley. These exposures occur atop Nankoweap Butte and within Awatubi and Sixtymile Canyons in the eastern Grand Canyon, Arizona. The maximum preserved thickness of the Sixtymile Formation is about . The actual depositional thickness of the Sixtymile Formation is unknown owing to erosion prior to deposition of the Tapeats Sandstone.Dehler, CM, SM Porter, and JM Timmons (2012) ''The Neoproterozoic Earth system revealed from the Chuar Group of Grand Canyon.'', in JM Timmons and KE Karlstrom, eds., pp. 49–72, ''Grand Canyon Geology: Two Billion Years of Earth's History.'' Special Paper no. 489. Geological Society of America, Boulder, Colorado. Sixtymile Formation and the underlying Chuar Group are preserved only in a broad asymmetric fold comprising both units, called the Chuar syncline. The ''Chuar Syncline'' is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chuar Group
The Neoproterozoic Chuar Group consists of of fossiliferous, unmetamorphosed sedimentary strata that is composed of about 85% mudrock. The Group is the approximate upper half of the Grand Canyon Supergroup, overlain by the thin, in comparison, Sixtymile Formation, the top member of the multi-membered Grand Canyon Supergroup. The mudrock is interbedded with meter-thick sandstone and dolomite beds. The mudrocks are typically gray to black when freshly exposed and weather to reddish or greenish colors. The fresh gray to black colors of the mudrocks are due to a high organic content. Some samples of these mudrocks contain high total organic carbon percentages that are as much 9.39 weight percent organic carbon. The sandstone beds often exhibit symmetrical ripple marks. These ripple marks are commonly draped with a thin veneer of mudstone with mudcracks. These strata have been subdivided into the Galeros Formation (lower) and the Kwagunt Formation (upper) using the base of the prom ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Geologic Formation
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 Wer ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Proterozoic
The Proterozoic () is a geological eon spanning the time interval from 2500 to 538.8million years ago. It is the most recent part of the Precambrian "supereon". It is also the longest eon of the Earth's geologic time scale, and it is subdivided into three geologic eras (from oldest to youngest): the Paleoproterozoic, Mesoproterozoic, and Neoproterozoic. The Proterozoic covers the time from the appearance of oxygen in Earth's atmosphere to just before the proliferation of complex life (such as trilobites or corals) on the Earth. The name ''Proterozoic'' combines two forms of ultimately Greek origin: meaning 'former, earlier', and , 'of life'. The well-identified events of this eon were the transition to an oxygenated atmosphere during the Paleoproterozoic; the evolution of eukaryotes; several glaciations, which produced the hypothesized Snowball Earth during the Cryogenian Period in the late Neoproterozoic Era; and the Ediacaran Period (635 to 538.8 Ma) which is characterize ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Strata
In geology and related fields, a stratum ( : strata) is a layer of rock or sediment characterized by certain lithologic properties or attributes that distinguish it from adjacent layers from which it is separated by visible surfaces known as either '' bedding surfaces'' or ''bedding planes''.Salvador, A. ed., 1994. ''International stratigraphic guide: a guide to stratigraphic classification, terminology, and procedure. 2nd ed.'' Boulder, Colorado, The Geological Society of America, Inc., 215 pp. . Prior to the publication of the International Stratigraphic Guide, older publications have defined a stratum as either being either equivalent to a single bed or composed of a number of beds; as a layer greater than 1 cm in thickness and constituting a part of a bed; or a general term that includes both ''bed'' and ''lamina''.Neuendorf, K.K.E., Mehl, Jr., J.P., and Jackson, J.A. , eds., 2005. ''Glossary of Geology'' 5th ed. Alexandria, Virginia, American Geological Institute. 779 pp. . ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Grand Canyon Lipan Point01
Grand may refer to: People with the name * Grand (surname) * Grand L. Bush (born 1955), American actor * Grand Mixer DXT, American turntablist * Grand Puba (born 1966), American rapper Places * Grand, Oklahoma * Grand, Vosges, village and commune in France with Gallo-Roman amphitheatre * Grand Concourse (other), several places * Grand County (other), several places * Grand Geyser, Upper Geyser Basin of Yellowstone * Grand Rounds National Scenic Byway, a parkway system in Minneapolis, Minnesota, United States * Le Grand, California, census-designated place * Grand Staircase, a place in the US. Arts, entertainment, and media * ''Grand'' (Erin McKeown album), 2003 * ''Grand'' (Matt and Kim album), 2009 * ''Grand'' (magazine), a lifestyle magazine related to related to grandparents * ''Grand'' (TV series), American sitcom, 1990 * Grand piano, musical instrument * Grand Production, Serbian record label company * The Grand Tour, a new British automobile show ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Colorado River
The Colorado River ( es, Río Colorado) is one of the principal rivers (along with the Rio Grande) in the Southwestern United States and northern Mexico. The river drains an expansive, arid drainage basin, watershed that encompasses parts of seven U.S. states and two Mexican states. The name Colorado derives from the Spanish language for "colored reddish" due to its heavy silt load. Starting in the central Rocky Mountains of Colorado, it flows generally southwest across the Colorado Plateau and through the Grand Canyon before reaching Lake Mead on the Arizona–Nevada border, where it turns south toward the Mexico–United States border, international border. After entering Mexico, the Colorado approaches the mostly dry Colorado River Delta at the tip of the Gulf of California between Baja California and Sonora. Known for its dramatic canyons, whitewater rapids, and eleven National parks of the United States, U.S. National Parks, the Colorado River and its tributaries are a v ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Grand Canyon
The Grand Canyon (, yuf-x-yav, Wi:kaʼi:la, , Southern Paiute language: Paxa’uipi, ) is a steep-sided canyon carved by the Colorado River in Arizona, United States. The Grand Canyon is long, up to wide and attains a depth of over a mile (). The canyon and adjacent rim are contained within Grand Canyon National Park, the Kaibab National Forest, Grand Canyon–Parashant National Monument, the Hualapai Indian Reservation, the Havasupai Indian Reservation and the Navajo Nation. President Theodore Roosevelt was a major proponent of the preservation of the Grand Canyon area and visited it on numerous occasions to hunt and enjoy the scenery. Nearly two billion years of Earth's geological history have been exposed as the Colorado River and its tributaries cut their channels through layer after layer of rock while the Colorado Plateau was uplifted. [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
