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Ripple Marks
In geology, ripple marks are sedimentary structures (i.e., bedforms of the lower flow regime) and indicate agitation by water (current or waves) or wind. Defining ripple cross-laminae and asymmetric ripples * ''Current ripple marks'', ''unidirectional ripples'', or ''asymmetrical ripple marks'' are asymmetrical in profile, with a gentle up-current slope and a steeper down-current slope. The down-current slope is the angle of repose, which depends on the shape of the sediment. These commonly form in fluvial and aeolian depositional environments, and are a signifier of the lower part of the Lower Flow Regime. * Ripple cross-laminae forms when deposition takes place during migration of current or wave ripples. A series of cross-laminae are produced by superimposing migrating ripples. The ripples form lateral to one another, such that the crests of vertically succeeding laminae are out of phase and appear to be advancing upslope. This process results in cross-bedded units t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ripple Marks In Moenkopi Formation Rock Off Of Capitol Reef Scenic Drive
Ripple may refer to: Science and technology * Capillary wave, commonly known as ripple, a wave traveling along the phase boundary of a fluid ** Ripple, more generally a disturbance, for example of spacetime in gravitational waves * Ripple (electrical), residual periodic variation in DC voltage during ac to dc conversion ** Ripple current, pulsed current draw caused by some non-linear devices and circuits ** Frequency-domain ripple ** Ringing (signal), oscillation of a signal, particularly in the step response * Polarization ripples, appearing after irradiation of a solid by energy flux (laser, ions, etc.) * Ripple marks, as identified in sediments and sedimentary rocks * Ripple (payment protocol), a real-time payment system by Ripple Labs * Ripple control, a form of electrical load management * Various brainwave patterns, including those which follow sharp waves in the hippocampus * Ripple I and Ripple II, 1962 US nuclear bomb tests in Operation Dominic Organizations * Ripple (c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dinosaur Ridge
Dinosaur Ridge is a segment of the Dakota Hogback in the Morrison Fossil Area National Natural Landmark located in Jefferson County, Colorado, near the town of Morrison and just west of Denver. The Dinosaur Ridge area is one of the world's most famous dinosaur fossil localities. In 1877, fossil excavation began at Dinosaur Ridge under the direction of paleontologist Othniel Charles Marsh. Some of the best-known dinosaurs were found here, including ''Stegosaurus'', ''Apatosaurus'', ''Diplodocus'', and ''Allosaurus''. In 1973, the area was recognized for its uniqueness as well as its historical and scientific significance when it was designated the Morrison Fossil Area National Natural Landmark by the National Park Service. In 1989, the Friends of Dinosaur Ridge formed to address increasing concerns regarding the preservation of the site and to offer educational programs on the area's resources. The rocks on the west side of Dinosaur Ridge are part of the widespread Morrison Form ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dakota Formation
The Dakota is a sedimentary geologic unit name of formation and group rank in Midwestern North America. The Dakota units are generally composed of sandstones, mudstones, clays, and shales deposited in the Mid-Cretaceous opening of the Western Interior Seaway.Monroe, James S. and Wicander, Reed (1997) ''The Changing Earth: Exploring Geology and Evolution'' (2nd edition) Wadsworth Publishing Company, Belmont, California, page 610, The usage of the name Dakota for this particular Albian-Cenomanian strata is exceptionally widespread; from British Columbia and Alberta to Montana and Wisconsin to Colorado and Kansas to Utah and Arizona. It is famous for producing massive colorful rock formations in the Rocky Mountains and the Great Plains of the United States, and for preserving both dinosaur footprints and early deciduous tree leaves. Owing to extensive weathering of older rocks during the Jurassic and Triassic, the Dakota strata lie unconformably atop many different formations rangin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 the entire Phanerozoic. The name is derived from the Latin ''creta'', "chalk", which is abundant in the latter half of the period. It is usually abbreviated K, for its German translation ''Kreide''. The Cretaceous was a period with a relatively warm climate, resulting in high eustatic sea levels that created numerous shallow inland seas. These oceans and seas were populated with now- extinct marine reptiles, ammonites, and rudists, while dinosaurs continued to dominate on land. The world was ice free, and forests extended to the poles. During this time, new groups of mammals and birds appeared. During the Early Cretaceous, flowering plants appeared and began to rapidly diversify, becoming the dominant group of plants across the Earth b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Crest Trough
Crest or CREST may refer to: Buildings *The Crest (Huntington, New York), a historic house in Suffolk County, New York *"The Crest", an alternate name for 63 Wall Street, in Manhattan, New York *Crest Castle (Château Du Crest), Jussy, Switzerland *Crest House, a building, now in ruins, at the summit of Mount Evans in Colorado *Crest Theatre, a historic theatre in downtown Sacramento, California *Crest Theatre, formerly Majestic Crest Theatre, Los Angeles, California *Crest Theatre, in Old School Square, Delray Beach, Florida Business or commerce *Crest (toothpaste), a brand of toothpaste *Crest Audio, an American manufacturer of power amplifiers and mixing consoles *Crest Animation Productions, an animation studio in Burbank, California *Crest Animation Studios, an animation studio in India *Crest Books, an imprint of now defunct Fawcett Publications *Crest Hotels, a defunct hotel chain in the UK *Crest Manufacturing Company, producer of the Crestmobile automobile in the 1900s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Transverse Aeolian Ridges
Transverse aeolian ridges (TARs) are visually bright features commonly found in topographic depressions on Mars. These small-scale and relict bedforms were first seen in narrow-angle images from the Mars Orbiter Camera (MOC) and were called “ridges” to preserve both dunes and ripples as formative mechanisms. While TARs are widespread on Mars, their formation, age, composition, and role in past Martian sediment cycles remain poorly constrained. Aeolian bedforms Aeolian bedforms are typically classified into either ripples or dunes based on their morphologies and formative mechanisms. Dunes are larger (>0.5 m or taller on Earth), typically asymmetrical in cross-profile, and are the product of hydrodynamic instability related to sand flux, the local topography, shear stress exerted by the wind on sand grains, and flow-form interactions induced by the topography of the dune itself. Wind ripples by comparison are small (amplitudes of 0.6 - 15 mm), are more symmetrical in profile, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Saltation (geology)
In geology, saltation () is a specific type of particle transport by fluids such as wind or water. It occurs when loose materials are removed from a bed and carried by the fluid, before being transported back to the surface. Examples include pebble transport by rivers, sand drift over desert surfaces, soil blowing over fields, and snow drift over smooth surfaces such as those in the Arctic or Canadian Prairies. Process At low fluid velocities, loose material rolls downstream, staying in contact with the surface. This is called ''creep'' or ''reptation''. Here the forces exerted by the fluid on the particle are only enough to roll the particle around the point of contact with the surface. Once the wind speed reaches a certain critical value, termed the ''impact'' or ''fluid threshold'', the drag and lift forces exerted by the fluid are sufficient to lift some particles from the surface. These particles are accelerated by the fluid, and pulled downward by gravity, causing them to t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
1969 Afghanistan (Sistan) Wind Ripples
This year is notable for Apollo 11's first landing on the moon. Events January * January 4 – The Government of Spain hands over Ifni to Morocco. * January 5 **Ariana Afghan Airlines Flight 701 crashes into a house on its approach to London's Gatwick Airport, killing 50 of the 62 people on board and two of the home's occupants. * January 14 – An explosion aboard the aircraft carrier USS ''Enterprise'' near Hawaii kills 27 and injures 314. * January 19 – End of the siege of the University of Tokyo, marking the beginning of the end for the 1968–69 Japanese university protests. * January 20 – Richard Nixon is First inauguration of Richard Nixon, sworn in as the 37th President of the United States. * January 22 – Attempted assassination of Leonid Brezhnev, An assassination attempt is carried out on Soviet leader Leonid Brezhnev by deserter Viktor Ilyin. One person is killed, several are injured. Leonid Brezhnev, Brezhnev escaped unharmed. * Januar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stream Bed
A stream bed or streambed is the bottom of a stream or river (bathymetry) or the physical confine of the normal water flow (Channel (geography), channel). The lateral confines or channel margins are known as the stream Bank (geography), banks or river banks, during all but flood stage. Under certain conditions a river can branch from one stream bed to multiple stream beds. A flood occurs when a stream overflows its banks and flows onto its flood plain. As a general rule, the bed is the part of the stream channel, channel up to the normal water line, and the banks are that part above the normal water line. However, because water flow varies, this differentiation is subject to local interpretation. Usually, the bed is kept clear of terrestrial vegetation, whereas the banks are subjected to water flow only during unusual or perhaps infrequent high water stages and therefore might support vegetation some or much of the time. The nature of any stream bed is always a function of th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sinusoidal
A sine wave, sinusoidal wave, or just sinusoid is a mathematical curve defined in terms of the '' sine'' trigonometric function, of which it is the graph. It is a type of continuous wave and also a smooth periodic function. It occurs often in mathematics, as well as in physics, engineering, signal processing and many other fields. Formulation Its most basic form as a function of time (''t'') is: y(t) = A\sin(2 \pi f t + \varphi) = A\sin(\omega t + \varphi) where: * ''A'', ''amplitude'', the peak deviation of the function from zero. * ''f'', ''ordinary frequency'', the ''number'' of oscillations (cycles) that occur each second of time. * ''ω'' = 2''f'', ''angular frequency'', the rate of change of the function argument in units of radians per second. * \varphi, ''phase'', specifies (in radians) where in its cycle the oscillation is at ''t'' = 0. When \varphi is non-zero, the entire waveform appears to be shifted in time by the amount ''φ''/''ω'' seconds. A negative value rep ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Symmetric
Symmetry (from grc, συμμετρία "agreement in dimensions, due proportion, arrangement") in everyday language refers to a sense of harmonious and beautiful proportion and balance. In mathematics, "symmetry" has a more precise definition, and is usually used to refer to an object that is invariant under some transformations; including translation, reflection, rotation or scaling. Although these two meanings of "symmetry" can sometimes be told apart, they are intricately related, and hence are discussed together in this article. Mathematical symmetry may be observed with respect to the passage of time; as a spatial relationship; through geometric transformations; through other kinds of functional transformations; and as an aspect of abstract objects, including theoretic models, language, and music. This article describes symmetry from three perspectives: in mathematics, including geometry, the most familiar type of symmetry for many people; in science and nature; and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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