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Caprock
Caprock or cap rock is a more resistant rock type overlying a less resistant rock type,Kearey, Philip (2001). ''Dictionary of Geology'', 2nd ed., Penguin Reference, London, New York, etc., p. 41.. . analogous to an upper crust on a cake that is harder than the underlying layer. Description The Niagara Escarpment, over which Niagara Falls flows, is an example of a scarp or escarpment. At Niagara Falls, the caprock is the riverbed above the falls, and is what prevents the river from eroding the face of the falls very quickly. In the photo, the dark thin layer in the foreground where water is not yet running, is the caprock. The Niagara caprock is made of dolomitic limestone. Other common types of caprock are sandstone and mafic rock. In processes such as scarp retreat, the caprock controls the rate of erosion of the scarp. As the softer rock is cut away, periodically the caprock shears off. Caprock is also found in salt domes and on the top of mesa formations. Petroleum I ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Scarp Retreat
Scarp retreat is a geological process through which the location of an escarpment changes over time. Typically the cliff is undermined, rocks fall and form a talus slope, the talus is chemically or mechanically weathered and then removed through water or wind erosion, and the process of undermining resumes. Scarps may retreat for tens of kilometers in this way over relatively short geological time spans, even in arid locations. Scarp profiles A scarp is a line of cliffs that has usually been formed by faulting or erosion. If it is protected by a strong caprock, or if it contains vertical fractures, it may retain its steep profile as it retreats. Scarps in dry climates typically have a near-vertical upper face, that may account for 10% - 75% of the total height, with a talus-covered sloping rampart forming the lower section. The caprock is undermined as the rampart and face are eroded, and eventually a section collapses. A strong caprock will typically create a relatively hig ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mesa
A mesa is an isolated, flat-topped elevation, ridge or hill, which is bounded from all sides by steep escarpments and stands distinctly above a surrounding plain. Mesas characteristically consist of flat-lying soft sedimentary rocks capped by a more resistant layer or layers of harder rock, e.g. shales overlain by sandstones. The resistant layer acts as a caprock that forms the flat summit of a mesa. The caprock can consist of either sedimentary rocks such as sandstone and limestone; dissected lava flows; or a deeply eroded duricrust. Unlike ''plateau'', whose usage does not imply horizontal layers of bedrock, e.g. Tibetan Plateau, the term ''mesa'' applies exclusively to the landforms built of flat-lying strata. Instead, flat-topped plateaus are specifically known as '' tablelands''.Duszyński, F., Migoń, P. and Strzelecki, M.C., 2019. ''Escarpment retreat in sedimentary tablelands and cuesta landscapes–Landforms, mechanisms and patterns.'' ''Earth-Science Reviews, no. 1028 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Caprock Canyons State Park And Trailway
Caprock Canyons State Park and Trailway is a Texas state park located along the eastern edge of the Llano Estacado in Briscoe County, Texas, United States, approximately southeast of Amarillo. The state park opened in 1982 and is in size, making it the third-largest state park in Texas. Recreation In 1993, a hiking, biking, and equestrian rail trail opened that stretches through the park through Floyd, Briscoe, and Hall counties. The trailway was created after the Texas Parks and Wildlife Department acquired of right-of-way from the abandoned Fort Worth and Denver Railroad's lines between Estelline and South Plains. File:Caprock Canyons Butte 2005.jpg, Isolated butte, an erosional remnant of the Llano Estacado. File:Caprock Canyons Side Canyon 2005.JPG, Side canyon carved by erosion. Climate The park is located in West Texas and has a semi-arid climate. The average January minimum temperature is and the average July maximum is . The park receives of precipitation ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Niagara Falls
Niagara Falls () is a group of three waterfalls at the southern end of Niagara Gorge, spanning the Canada–United States border, border between the Provinces and territories of Canada, province of Ontario in Canada and the U.S. state, state of New York (state), New York in the United States. The largest of the three is Horseshoe Falls, which straddles the Canada–United States border, international border of the two countries. It is also known as the Canadian Falls. The smaller American Falls and Bridal Veil Falls (Niagara Falls), Bridal Veil Falls lie within the United States. Bridal Veil Falls is separated from Horseshoe Falls by Goat Island (New York), Goat Island and from American Falls by Luna Island, with both islands situated in New York. Formed by the Niagara River, which drains Lake Erie into Lake Ontario, the combined falls have the List of waterfalls by flow rate, highest flow rate of any waterfall in North America that has a vertical drop of more than . During p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Niagara Escarpment
The Niagara Escarpment is a long escarpment, or cuesta, in Canada and the United States that runs predominantly east–west from New York through Ontario, Michigan, Wisconsin, and into Illinois. The escarpment is most famous as the cliff over which the Niagara River plunges at Niagara Falls, for which it is named. The escarpment is a UNESCO World Biosphere Reserve. The reserve has the oldest forest ecosystem and trees in eastern North America. The escarpment is not a fault line but the result of unequal erosion. It is composed of an outcrop belt of the Lockport Formation of Silurian age, and is similar to the Onondaga Formation, which runs in a parallel outcrop belt just to the south, through western New York and southern Ontario. The escarpment is the most prominent of several escarpments formed in the bedrock of the Great Lakes Basin. From its easternmost point near Watertown, New York, the escarpment shapes in part the individual basins and landforms of Lake Ontar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Anhydrite
Anhydrite, or anhydrous calcium sulfate, is a mineral with the chemical formula CaSO4. It is in the orthorhombic crystal system, with three directions of perfect cleavage parallel to the three planes of symmetry. It is not isomorphous with the orthorhombic barium (baryte) and strontium ( celestine) sulfates, as might be expected from the chemical formulas. Distinctly developed crystals are somewhat rare, the mineral usually presenting the form of cleavage masses. The Mohs hardness is 3.5, and the specific gravity is 2.9. The color is white, sometimes greyish, bluish, or purple. On the best developed of the three cleavages, the lustre is pearly; on other surfaces it is glassy. When exposed to water, anhydrite readily transforms to the more commonly occurring gypsum, (CaSO4·2H2O) by the absorption of water. This transformation is reversible, with gypsum or calcium sulfate hemihydrate forming anhydrite by heating to around under normal atmospheric conditions. Anhydrite is common ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Salt Dome
A salt dome is a type of structural dome formed when salt (or other evaporite minerals) intrudes into overlying rocks in a process known as diapirism. Salt domes can have unique surface and subsurface structures, and they can be discovered using techniques such as seismic reflection. They are important in petroleum geology as they can function as petroleum traps. Formation Stratigraphically, salt basins developed periodically from the Proterozoic to the Neogene. The formation of a salt dome begins with the deposition of salt in a restricted basin. In these basins, the outflow of water exceeds inflow. More concretely, the basin loses water through evaporation, resulting in the precipitation and deposition of salt. While the rate of sedimentation of salt is significantly larger than the rate of sedimentation of clastics, it is recognized that a single evaporation event is rarely enough to produce the vast quantities of salt needed to form a layer thick enough for the f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rock (geology)
In geology, rock (or stone) is any naturally occurring solid mass or aggregate of minerals or mineraloid matter. It is categorized by the minerals included, its chemical composition, and the way in which it is formed. Rocks form the Earth's outer solid layer, the crust, and most of its interior, except for the liquid outer core and pockets of magma in the asthenosphere. The study of rocks involves multiple subdisciplines of geology, including petrology and mineralogy. It may be limited to rocks found on Earth, or it may include planetary geology that studies the rocks of other celestial objects. Rocks are usually grouped into three main groups: igneous rocks, sedimentary rocks and metamorphic rocks. Igneous rocks are formed when magma cools in the Earth's crust, or lava cools on the ground surface or the seabed. Sedimentary rocks are formed by diagenesis and lithification of sediments, which in turn are formed by the weathering, transport, and deposition of exi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oil Reservoir
A petroleum reservoir or oil and gas reservoir is a subsurface accumulation of hydrocarbons contained in porous or fractured rock formations. Such reservoirs form when kerogen (ancient plant matter) is created in surrounding rock by the presence of high heat and pressure in the Earth's crust. Petroleum reservoirs are broadly classified as ''conventional'' and '' unconventional'' reservoirs. In conventional reservoirs, the naturally occurring hydrocarbons, such as crude oil or natural gas, are trapped by overlying rock formations with lower permeability, while in unconventional reservoirs, the rocks have high porosity and low permeability, which keeps the hydrocarbons trapped in place, therefore not requiring a cap rock. Reservoirs are found using hydrocarbon exploration methods. Oil field An oil field is an area of accumulation of liquid oil underground in multiple (potentially linked) reservoirs, trapped as it rises by impermeable rock formations. In industrial terms, an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hoodoo (geology)
A hoodoo (also called a tent rock, fairy chimney, or earth pyramid) is a tall, thin spire of rock formed by erosion. Hoodoos typically consist of relatively soft rock topped by harder, less easily eroded stone that protects each column from the elements. They generally form within sedimentary rock and volcanic rock formations. Hoodoos range in size from the height of an average human to heights exceeding a 10-story building. Hoodoo shapes are affected by the erosional patterns of alternating hard and softer rock layers. Minerals deposited within different rock types can cause hoodoos to have different colors throughout their height. Etymology In certain regions of western North America these rocky structures are called hoodoos. The name is derived from Hoodoo spirituality, in which certain natural forms are said to possess certain powers, but by the late 19th century, this spirituality became associated with bad luck. Prior to the English name for these geographic formations ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Caprock Escarpment
The Caprock Escarpment is a term used in West Texas and Eastern New Mexico to describe the geographical transition point between the level High Plains of the Llano Estacado and the surrounding rolling terrain. In Texas, the escarpment stretches around south-southwest from the northeast corner of the Texas Panhandle near the Oklahoma border. The escarpment is especially notable, from north to south, in Briscoe, Floyd, Motley, Crosby, Dickens, Garza, and Borden Counties. In New Mexico, a prominent escarpment exists along the northernmost extension of the Llano Estacado, especially to the south of San Jon and Tucumcari, both in Quay County, New Mexico. Along the western edge of the Llano Estacado, the portion of the escarpment that stretches from Caprock to Maljamar, New Mexico, is called the Mescalero Ridge. Description The escarpment is made of caliche—a layer of calcium carbonate that resists erosion. In some places, the escarpment rises around above the plains ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Calcite
Calcite is a carbonate mineral and the most stable polymorph of calcium carbonate (CaCO3). It is a very common mineral, particularly as a component of limestone. Calcite defines hardness 3 on the Mohs scale of mineral hardness, based on scratch hardness comparison. Large calcite crystals are used in optical equipment, and limestone composed mostly of calcite has numerous uses. Other polymorphs of calcium carbonate are the minerals aragonite and vaterite. Aragonite will change to calcite over timescales of days or less at temperatures exceeding 300 °C, and vaterite is even less stable. Etymology Calcite is derived from the German ''Calcit'', a term from the 19th century that came from the Latin word for lime, ''calx'' (genitive calcis) with the suffix "-ite" used to name minerals. It is thus etymologically related to chalk. When applied by archaeologists and stone trade professionals, the term alabaster is used not just as in geology and mineralogy, where it is res ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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