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Topic: Impact crater

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In the News (Tue 16 Jul 19)

  Lunar Impact Crater Geology and Structure
Bessel Crater, 16 kilometers in diameter and 2 kilometers deep, is an example of a transitional crater between simple and complex craters.
Copernicus Crater, 93 kilometers in diameter, is one of the youngest and freshest impact craters on the nearside of the Moon.
Schrodinger is one of the youngest, freshest impact basins on the Moon.
www.lpi.usra.edu /expmoon/science/craterstructure.html   (1154 words)

  NationMaster - Encyclopedia: Clavius (crater)
Scheiner is a lunar impact crater that lies to the west of the enormous Clavius walled-plain.
The crater floor retains a diminshed remnant of a central massif, which lies between Clavius C and N. The relative smoothness of the floor and the low size of the central peaks may indicate that the crater surface was formed some time after the original impact.
This is a well-known lunar impact crater 83km in diameter and lies on the eastern edge of the Mare Imbrium.
www.nationmaster.com /encyclopedia/Clavius-(crater)   (1112 words)

 ESA - Mars Express - ‘Butterfly’ impact crater in Hesperia Planum
A large elliptical impact crater is visible within the scene, measuring approximately 24.4 km long, 11.2 km wide and reaching a maximum depth of approximately 650 metres below the surrounding plains.
This appears to be an impact crater that was subsequently resurfaced by lava flows, preserving the outline of the underlying crater.
The long axis of the impact crater is viewed as the impacting direction of the projectile.
www.esa.int /SPECIALS/Mars_Express/SEMZLM8A9HE_0.html   (388 words)

 Teacher Page: Impact Craters
The factors affecting the appearance of impact craters and ejecta are the size and velocity of the impactor, and the geology of the target surface.
Famous impact craters on Earth are Meteor Crater in Arizona, U.S.A.; Manicouagan in Quebec, Canada; Sudbury in Ontario, Canada; Ries Crater in Germany, and Chicxulub on the Yucatan coast in Mexico.
Chicxulub is considered by most scientists as the source crater of the catastrophe that led to the extinction of the dinosaurs at the end of the Cretaceous period.
www.spacegrant.hawaii.edu /class_acts/CratersTe.html   (1178 words)

 Terrestrial Impact Craters
Impact craters are geologic structures formed when a large meteoroid, asteroid or comet smashes into a planet or a satellite.
In larger craters, however, gravity causes the initially steep crater walls to collapse downward and inward, forming a complex structure with a central peak or peak ring and a shallower depth compared to diameter (1:10 to 1:20).
Chemical, isotopic, and age studies demonstrate that the crater is the most probable source for the Ivory Coast tektites, which are found on land in the Ivory Coast region of central Africa and as microtektites in nearby ocean sediments.
www.solarviews.com /eng/tercrate.htm   (2496 words)

 Spartanburg SC | GoUpstate.com | Spartanburg Herald-Journal   (Site not responding. Last check: )
If Silverpit is indeed an impact crater, this may imply that the Earth was struck at that time by several objects, possibly in a similar event to the collision of Comet Shoemaker-Levy 9 with Jupiter in 1994.
The crater was discovered during analysis of seismic data collected by petroleum geoscientists Simon Stewart of BP and Philip Allen of Production Geoscience Ltd, for a region 130 km off the Humber estuary, during a routine search for fossil fuel deposits.
A complicating factor is that almost all known impact craters are on land, whereas two-thirds of impacting objects will land in oceans and seas, so the results of impacts on water are much less well established than those of impacts on land.
www.goupstate.com /apps/pbcs.dll/section?category=NEWS&template=wiki&text=Silverpit_crater   (1514 words)

 Straight Dope Staff Report: Why are craters always round?
The reasons for non-circular craters include the degradation or modification of the crater with age, the material strength of the target compared to the energy of the impact, and, yes, the angle of impact.
Impact angle has an influence on the shape of a crater, but the effect is small except when the angle is shallow, typically less than 20 degrees.
Specifically, if the crater is large enough to be "complex" (rather than a simple bowl shape) we can look at interior structures such as the central peak or peak-ring in craters that have them and, outside the crater itself, at the ejecta (the debris that gets thrown out of an impact crater).
www.straightdope.com /mailbag/mcraters.htm   (1199 words)

 Impact Crater Images
Aorounga impact crater, Chad offers an SIR-C/X image of this crater which some scientists suggest is part of a string of impact craters formed by multiple impacts.
Impact Craters Activity by the Hawaii Space Grant Consortium offers a teaching guide for a "hands-on" activity to determine factors affecting the appearance of impact craters and ejecta.
Terrestrial Impact Crater List lists a number of impact craters and includes a panoramic Quicktime movie view of Meteor Crater, Arizona as well as an MPEG movie of a simulation of an impact event.
www.pibburns.com /catastro/impactim.htm   (938 words)

 The Year in Pictures: 2006 - Explore the Cosmos | The Planetary Society
Chains of dark spots are secondary impact craters formed by sprays of ejecta blocks thrown out of the impact crater.
This crater, in Arabia Terra, is surrounded by rays and bands of dark material that were deposited as a result of the expanding shock wave of the impact.
The new craters are not just a curiosity -- they yield important clues for understanding the space environments of both Mars and Earth, the impact hazard to future Mars astronauts, and the cratering rate experienced by recently deposited materials on Mars.
www.planetary.org /explore/topics/mars_global_surveyor/year2006_fresh_craters.html   (269 words)

 ScienceDaily: Near-Earth Object Impact Articles
An impact crater is a circular depression on a surface, usually referring to a planet, moon, asteroid, or other celestial body, caused by a collision of a smaller body (meteor) with the surface.
Impact events are caused by the collision of large meteoroids, asteroids or comets (generically: bolides) with Earth and may sometimes be followed by mass extinctions of life.
Chicxulub Crater is an ancient impact crater buried underneath the Yucatan peninsula, with its center located approximately underneath the town of Chicxulub, Yucatan, Mexico.
www.sciencedaily.com /articles/earth_climate/near-earth_object_impacts   (578 words)

 SPACE.com -- Study: Newfound Crater Under North Sea Carved by Asteroid   (Site not responding. Last check: )
Impact craters are often not visible on Earth's surface, because over time older ones are folded into the planet by shifting tectonic plates.
Importantly, the impact appears to have occurred in shallow water, researchers say, and so the crater was rapidly buried after its formation and therefore largely preserved.
Assuming the crater was carved by an asteroid, or possibly a comet, Stewart estimates the rock would have been a bit wider than a football field is long.
www.space.com /scienceastronomy/newfound_crater_020731.html   (812 words)

 Deep Impact - Research - The Open University
Not only are asteroid impacts implicated in mass extinctions, they form traps for oil and gas, and in the early history of the Earth and Mars, they may have been important habitats for life.
The crater was formed in a very shallow sea on a flat continental shelf sixty five million years ago, at the same time as the Chicxulub crater in Mexico, though it has not been possible to determine whether the two happened at exactly the same time.
The fact that Boltysh remained a hole in the ground on the flat continental shelf means that it holds a unique and near continuous record of the KT boundary (between the age of dinosaurs and the age of mammals) and early Paleogene period.
www.open.ac.uk /research/research-highlights/environment/deep-impact.php   (678 words)

 Auburn University Geology Department Virtual Field Trips Wetumpka Impact Structure
Impact craters are usually caused by meteors that strike the surface of a planet or planetary body.
Simple impact craters are circular, bowl-shaped depressions with well defined, raised rims and an interior slope that is steepest near the rim and smoothly decreases toward the crater's center.
The central peaks are not piles of debris that slid down the crater walls and came to rest in the center of the floor but are rocks from beneath the crater floor that were uplifted during the impact of the meteorite.
www.auburn.edu /academic/science_math/geology/docs/wetumpka/gen.htm   (1086 words)

 Earth Impact Database
Some buried craters have been revealed solely by geophysical techniques, although drill core is typically required to reveal macro- and microscopic evidence to prove an impact origin.
Presence of an impact melt sheet and/or dikes, and impact melt breccias that were generated due to hypervelocity impact (macroscopic).
Impact melt sheets are recognized by careful mapping and rock sampling followed by microscopy and geochemical analysis.
www.unb.ca /passc/ImpactDatabase   (1054 words)

 Meteor Impact Craters
Craters are bowl shaped depressions made when a meteorite collides with a planet or moon.
During impact, debris is thrown from the crater.
This peak is caused by the surface's attempt to rebound from the impact.
liftoff.msfc.nasa.gov /Academy/SPACE/SolarSystem/Meteors/Craters.html   (332 words)

 Haughton Crater | NASA Haughton-Mars Project
The Haughton meteorite impact crater, on Devon Island, Nunavut, in the Canadian high arctic, is 20 km in diameter and formed 23 million years ago.
It is one of the highest-latitude terrestrial impact craters known on land (75°22'N, 89°41'W).
However, particularly distinctive at Haughton is the crater's allochthonous impact breccia formation, a rubble deposit resulting from the launching, airborne mixing, fallback and weak rewelding of impact-shattered fragments derived from the entire stack of excavated rocks.
www.arctic-mars.org /about/crater.html   (701 words)

 MBG: Research: Bolivia: Meteorite Impact Crater   (Site not responding. Last check: )
The crater is approximately 8 km across and was produced by the collision of a meteorite about 200 m in diameter.
The crater was originally identified in the mid-1980s with satellite imagery, but a previous attempt to visit the site in 1987 was unsuccessful due to the remoteness of the locality.
Similarly, the savanna patch found in the center of the crater had top soil characteristics intermediate to open grassland and closed forest, reflecting the its grass sward and the presence of a numerous shrubs and herbaceous forbs (Table 2).
www.mobot.org /mobot/research/bolivia/craternew/welcome.shtml   (1007 words)

 PSR Discoveries: Hot Idea: Damage by Impact at Meteor Crater
Winds in excess of 1000 km/hour scoured the land within 3 to 5 km of the point of impact and led to swift devastation of the local population of plants and animals.
Since no one has ever observed the production of an impact crater on any rocky planet, we must use the size and shape of the craters, the presence of excavated bedrock, the shape and extent of the ejecta, and over-turned rock layers in the crater rims to understand the cratering process.
Researchers are gaining more understanding of the interplay between impact energy, target rock strength and structure, presence or absence of volatiles, and gravity from their studies of impact craters throughout the Solar System.
www.psrd.hawaii.edu /Dec97/impactBlast.html   (2150 words)

 BBC NEWS | Science/Nature | Huge impact crater found in Egypt
The heat from this impact may be responsible for the extensive field of "Desert Glass", yellow-green silica glass fragments found on the desert surface between the giant dunes of the Great Sand Sea in southwestern Egypt.
The crater's vast area suggests the location may have been hit by a meteorite equivalent in size to the diameter of the famous Meteor (or Barringer) Crater in Arizona which is 1.2km across.
The 65 million-year-old Chicxulub crater in Mexico is estimated to be 160 to 240km (100 to 150 miles) wide and is a likely culprit in the extinction of the dinosaurs.
news.bbc.co.uk /1/hi/sci/tech/4779482.stm   (357 words)

 Geotimes - June 2004 - Possible P/T impact crater
Ever since scientists found the Chicxulub crater in Mexico and blamed it for the mass extinction at the end of the Cretaceous, scientists have been trying to locate a crater on which to pin the even larger mass extinction at the end of the Permian.
Becker led a team that recently announced the discovery of an impact crater off the northwest coast of Australia that they say could be the killer of most of Earth’s life 251 million years ago.
It has all the stereotypical signs of an impact crater, says Robert Poreda, a geochemist at the University of Rochester in New York and one of the team members: the right size, age and other characteristics.
www.geotimes.org /july04/NN_PTimpact.html   (774 words)

 Chicxulub Impact Crater | Planeta
The existence of the crater was first detected during offshore petroleum explorations in the 1950s.
The crater was named after the nearby Mayan village of Chicxulub, and geologists continue to study the area.
Whether or not the meteor's impact was responsible for the demise of the dinosaurs (first proposed in 1980 by Walter Alvarez of the University of California at Berkeley) is argued in scientific circles, but an obvious consequence of the impact can be found in the nearby geography.
www.planeta.com /ecotravel/mexico/yucatan/chicxulub.html   (338 words)

 Impact craters
Impact craters are the most characteristic features of planetary bodies.
This form is characteristic of most of the martian impact craters which display striking "lobate" ejecta -- highly suggestive that the surface was saturated with water ice when the event took place.
Craters are a most useful tool to establish the relative ages of surfaces and thus to better understand how a planet has evolved, for example, to learn what have been the rates of erosion and sedimentation.
cmex.ihmc.us /CMEX/data/SiteCat/sitecat2/crater.htm   (1048 words)

 GSA Field Forum - Marine impact craters on Earth: Wetumpka impact structure   (Site not responding. Last check: )
Marine impact craters on Earth: Field investigation of the Wetumpka impact structure, a well-preserved marine impact crater, and the K-T boundary in the Alabama Gulf Coastal Plain
Artist's conception of Wetumpka impact crater during the early modification stage (after water resurge and collapse of southern rim).
A benefit of sediment cover is that it provides the crater with good protection against later erosion once the seafloor is subaerially exposed; thus, some marine-target craters are among the best-preserved craters in the world.
www.geosociety.org /fieldForums/07wetumpka.htm   (690 words)

 Reference.com/Encyclopedia/Sudbury Basin
It was created as the result of a 10 km cometary impact that occurred 1.85 billion years ago in the Paleoproterozoic era.
Sudbury Basin would then be the second largest crater on earth, after the 300 km Vredefort crater in South Africa, and larger than the 170 km Chicxulub crater in Yucatán, Mexico which is linked to the extinction of the dinosaurs.
The Sudbury Basin is deformed on the east by the Lake Wanapitei impact structure, a smaller 37 Mya impact crater.
www.reference.com /browse/wiki/Sudbury_Basin   (445 words)

 Deep Impact: Science: Cratering   (Site not responding. Last check: )
In the first situation, the crater formation is governed mostly by the gravity of the comet nucleus (known as a "gravity-dominated" process).
In this model, the crater may be as large as a football stadium (around 200 meters in diameter), and 30-50 meters deep.
If the crater turns out to be gravity-dominated, this lends evidence to the theory that the comet's nucleus consists of porous, pristine, unprocessed material, and that the comet formed by accretion.
deepimpact.umd.edu /science/cratering.html   (1769 words)

 Meteor impacts: Life's jump starter?
Meteor impacts are generally regarded as monstrous killers and one of the causes of mass extinctions throughout the history of life.
The idea that meteor impacts could benefit or even create conditions suitable for the beginning of early life struck Canadian Space Agency geologist Gordon Osinski while he and colleagues were conducting a geological survey of the 24-kilometer (15-mile) diameter Haughton Crater.
Impact craters of that age were long ago erased on Earth by erosion, volcanic resurfacing and plate tectonics.
www.physorg.com /news5686.html   (733 words)

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