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The rocks cycle describes how rocks are formed or change over time. All rocks start as magma and cool into igneous rocks. These are typically. The sedimentary rocks in the ocean are pushed under the continental crust and turned into metamorphic and igneous rocks. Main · Videos; Cuales son los 10 primeros numeros primos yahoo dating for cyst into the lop into the first date? lord, lop me tastefully to lop this cyst personally . dating site using facebook for advertising · what is the rock cycle yahoo dating .
An illustration of the three types of faults. Strike-slip faults occur when rock units slide past one another. Normal faults occur when rocks are undergoing horizontal extension. Reverse or thrust faults occur when rocks are undergoing horizontal shortening. The geology of an area changes through time as rock units are deposited and inserted, and deformational processes change their shapes and locations. Rock units are first emplaced either by deposition onto the surface or intrusion into the overlying rock.
Deposition can occur when sediments settle onto the surface of the Earth and later lithify into sedimentary rock, or when as volcanic material such as volcanic ash or lava flows blanket the surface. Igneous intrusions such as batholithslaccolithsdikesand sillspush upwards into the overlying rock, and crystallize as they intrude. Deformation typically occurs as a result of horizontal shortening, horizontal extensionor side-to-side strike-slip motion.
These structural regimes broadly relate to convergent boundariesdivergent boundariesand transform boundaries, respectively, between tectonic plates. When rock units are placed under horizontal compressionthey shorten and become thicker.
Because rock units, other than muds, do not significantly change in volumethis is accomplished in two primary ways: In the shallow crust, where brittle deformation can occur, thrust faults form, which causes deeper rock to move on top of shallower rock.
Because deeper rock is often older, as noted by the principle of superpositionthis can result in older rocks moving on top of younger ones. Movement along faults can result in folding, either because the faults are not planar or because rock layers are dragged along, forming drag folds as slip occurs along the fault. Deeper in the Earth, rocks behave plastically and fold instead of faulting.
These folds can either be those where the material in the center of the fold buckles upwards, creating " antiforms ", or where it buckles downwards, creating " synforms ". If the tops of the rock units within the folds remain pointing upwards, they are called anticlines and synclinesrespectively. If some of the units in the fold are facing downward, the structure is called an overturned anticline or syncline, and if all of the rock units are overturned or the correct up-direction is unknown, they are simply called by the most general terms, antiforms and synforms.
A diagram of folds, indicating an anticline and a syncline. Even higher pressures and temperatures during horizontal shortening can cause both folding and metamorphism of the rocks. This metamorphism causes changes in the mineral composition of the rocks; creates a foliationor planar surface, that is related to mineral growth under stress. This can remove signs of the original textures of the rocks, such as bedding in sedimentary rocks, flow features of lavasand crystal patterns in crystalline rocks.
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Extension causes the rock units as a whole to become longer and thinner. This is primarily accomplished through normal faulting and through the ductile stretching and thinning. Normal faults drop rock units that are higher below those that are lower.
This typically results in younger units ending up below older units.
Stretching of units can result in their thinning. In fact, at one location within the Maria Fold and Thrust Beltthe entire sedimentary sequence of the Grand Canyon appears over a length of less than a meter. Rocks at the depth to be ductilely stretched are often also metamorphosed. These stretched rocks can also pinch into lenses, known as boudinsafter the French word for "sausage" because of their visual similarity.
Where rock units slide past one another, strike-slip faults develop in shallow regions, and become shear zones at deeper depths where the rocks deform ductilely. Geologic cross section of Kittatinny Mountain. This cross section shows metamorphic rocks, overlain by younger sediments deposited after the metamorphic event. These rock units were later folded and faulted during the uplift of the mountain.
The addition of new rock units, both depositionally and intrusively, often occurs during deformation. Faulting and other deformational processes result in the creation of topographic gradients, causing material on the rock unit that is increasing in elevation to be eroded by hillslopes and channels.
These sediments are deposited on the rock unit that is going down. Continual motion along the fault maintains the topographic gradient in spite of the movement of sediment, and continues to create accommodation space for the material to deposit. Deformational events are often also associated with volcanism and igneous activity.
How does plate tectonics affect the rock cycle? | Socratic
Volcanic ashes and lavas accumulate on the surface, and igneous intrusions enter from below. Dikeslong, planar igneous intrusions, enter along cracks, and therefore often form in large numbers in areas that are being actively deformed. This can result in the emplacement of dike swarmssuch as those that are observable across the Canadian shield, or rings of dikes around the lava tube of a volcano. All of these processes do not necessarily occur in a single environment, and do not necessarily occur in a single order.
The Hawaiian Islandsfor example, consist almost entirely of layered basaltic lava flows. The sedimentary sequences of the mid-continental United States and the Grand Canyon in the southwestern United States contain almost-undeformed stacks of sedimentary rocks that have remained in place since Cambrian time.
Other areas are much more geologically complex. In the southwestern United States, sedimentary, volcanic, and intrusive rocks have been metamorphosed, faulted, foliated, and folded. Even older rocks, such as the Acasta gneiss of the Slave craton in northwestern Canadathe oldest known rock in the world have been metamorphosed to the point where their origin is undiscernable without laboratory analysis.
In addition, these processes can occur in stages. In many places, the Grand Canyon in the southwestern United States being a very visible example, the lower rock units were metamorphosed and deformed, and then deformation ended and the upper, undeformed units were deposited.
Although any amount of rock emplacement and rock deformation can occur, and they can occur any number of times, these concepts provide a guide to understanding the geological history of an area.
Sedimentary rocks are formed because of the overburden pressure as particles of sediment are deposited out of air, ice, wind, gravity, or water flows carrying the particles in suspension. Igneous rocks, which are formed from magma cooling underground, or lava above ground are formed from previous igneous, metamorphic, or sedimentary rocks which have become melted, usually as a result of plate collision and subduction.
Rhythmic Layering - Alternating parallel layers having different properties. This results in bedding showing a decrease in grain size from the bottom of the bed to the top of the bed. London Dates in London: This can occur in lakes that have no outlets like the Great Salt Lake or restricted ocean basins, like has happened in the Mediterranean Sea or the Gulf of Mexico in the past.
These rocks are very useful for building and architecture. They contain fossils, the preserved remains of ancient plants and animals.
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Organic-rich shales are the source of petroleum. Need a helping hand? Browse our wide selection of profiles or attend a singles event in the Scottish capital. Sedimentary rocks are formed because of the overburden pressure as particles of sediment are deposited out of air, ice, wind, or water flows carrying the particles in suspension.
For example, a conglomerate may include fragments of quartz, limestone, chert, etc. Very common in beach deposits, sand dunes, and river deposited sediment.Rocks Types & Rocks Cycle - Video for Kids by moadarticle.info
A sequence of strata that is sufficiently unique to be recognized on a regional scale is termed a formation. Which book do you want? You can get more information at following link. Four basic processes are involved in the formation of a clastic sedimentary rock: A series of beds are referred to as strata. Because life has evolved - fossils give clues to relative age of the sediment.
Among the types of rock produced by this process are: Such red colored rocks are often referred to as red beds.
Mudrocks Mudrocks are made of fine grained clasts silt and clay sized. A few lines are enough to make an impression. Sedimentary rocks are laid down in layers called beds or strata.