Difference between revisions 1211294 and 1211316 on enwikiversity

[[Image:Chain of impact craters on Ganymede.jpg|thumb|right|200px|The image shows a chain of craters on Ganymede. Credit: Galileo Project, Brown University, JPL, NASA.]]
{{complete}}
A '''crater''' may be any large, roughly circular, depression or hole in or beneath the rocky surface of a rocky object.
{{experimental}}
(contracted; show full)

For crater astronomy, the proof of concept is demonstrated by unique or novel [[astronomy]] in any band that explores craters to reveal knowledge, especially regarding their formation.

=
Meteors=

MeteorsRadiation=

Radiation that may produce a crater are likely larger than subatomic particles. The range of size and composition of meteors is large. Meteorsthis radiation is large. Such radiation may be rocky, liquid, gaseous, or plasma, a moving galaxy cluster to down to the size of an atom, molecule, or dust.

The characteristics of the crater likely depend on the energy of impact broken down into at least angle, speed, media, and dissipation.

=Planetary geology=
[[Image:Moon-apollo17-schmitt boulder.jpg|thumb|right|200px|Planetary geologist and NASA astronaut Harrison "Jack" Schmitt collects lunar samples during the Apollo 17 mission. Credit: NASA.]]
(contracted; show full)|doi=10.1130/​0091-7613(1993)​021<0435:CASQDI>​2.3.CO;2
|pmid=
|pdf=
|accessdate=2012-10-23 }}</ref>
{{clear}}

=Theoretical crater astronomy=

⏎
=Entities=
[[Image:Vulkanbombeneinschlag.png|thumb|right|200px|A volcanic bomb has deformed the rock strata. Credit: [[:de:User:Drucker03|Drucker03]].]]
'''Def.'''
# the "study of rock layers and the layering process [of] stratification"<ref name=StratigraphyWikt>{{ cite web
|title=stratigraphy, In: ''Wiktionary''
|publisher=Wikimedia Foundation, Inc
|location=San Francisco, California
|month=October 8,
|year=2013
|url=https://en.wiktionary.org/wiki/stratigraphy
|accessdate=2013-10-18 }}</ref> or
# "the layering of deposits, with newer remains overlaying older ones, forming a chronology of the site"<ref name=StratigraphyWikt/>

is called '''stratigraphy'''.

'''Def.''' "the process leading to the formation or deposition of layers, especially of sedimentary rocks"<ref name=StratificationWikt>{{ cite web
|title=stratification, In: ''Wiktionary''
|publisher=Wikimedia Foundation, Inc
|location=San Francisco, California
|month=June 19,
|year=2013
|url=https://en.wiktionary.org/wiki/stratification
|accessdate=2013-10-18 }}</ref> is called '''stratification'''.

'''Def.'''
# one "of several parallel horizontal layers of material arranged one on top of another",<ref name=StratumWikt>{{ cite web
|title=stratum, In: ''Wiktionary''
|publisher=Wikimedia Foundation, Inc
|location=San Francisco, California
|month=October 6,
|year=2013
|url=https://en.wiktionary.org/wiki/stratum
|accessdate=2013-10-18 }}</ref>
# a "layer of sedimentary rock having approximately the same composition throughout",<ref name=StratumWikt/> or
# any "of the regions of the atmosphere, such as the stratosphere, that occur as layers"<ref name=StratumWikt/>

is called a '''stratum''', plural '''strata'''.

Natural bombs may produce impact craters and deform rock strata.
{{clear}}

=Sources=
[[Image:Mount Tambora Volcano, Sumbawa Island, Indonesia.jpg|thumb|right|200px|This detailed astronaut photograph depicts the summit caldera of the Mount Tambora. Credit: NASA ISS Expedition 20 crew.]]

The second image at right is a "detailed astronaut photograph [that] depicts the summit caldera of the volcano. The huge caldera—6 kilometers (3.7 miles) in diameter and 1,100 meters (3,609 feet) deep—formed when Tambora’s estimated 4,000-meter- (13,123-foot) high peak was removed, and the magma chamber below emptied during the April 10 eruption. Today the crater floor is occupied by an ephemeral freshwater lake, recent sedimentary deposits, and minor lava flows and domes from the nineteenth and twentieth centuries. Layered tephra deposits are visible along the northwestern crater rim. Active fumaroles, or steam vents, still exist in the caldera."<ref name=Wiscombe>{{ cite web
|author=Warren Wiscombe
|title=Mount Tambora Volcano, Sumbawa Island, Indonesia
|publisher=NASA Earth Observatory
|location=
|month=July 19,
|year=2009
|url=http://earthobservatory.nasa.gov/IOTD/view.php?id=39412
|pdf=
|accessdate=2013-03-30 }}</ref>

"On April 10, 1815, the Tambora Volcano produced the largest eruption in recorded history. An estimated 150 cubic kilometers (36 cubic miles) of tephra—exploded rock and ash—resulted, with ash from the eruption recognized at least 1,300 kilometers (808 miles) away to the northwest. While the April 10 eruption was catastrophic, historical records and geological analysis of eruption deposits indicate that the volcano had been active between 1812 and 1815. Enough ash was put into the atmosphere from the April 10 eruption to reduce incident sunlight on the Earth’s surface, causing global cooling, which resulted in the 1816 “year without a summer.”"<ref name=Wiscombe/>
{{clear}}

=Objects=
[[Image:Mare Imbrium-Apollo17.jpg|thumb|200px|right|Mare Imbrium (foreground) is peppered with secondary craters from the impact that formed Copernicus crater (upper center). Credit: NASA.]]
'''Def.''' "[a] hemispherical pit ... [a] basinlike opening or mouth ... about which a cone is often built up ... any large roughly circular depression or hole"<ref name=CraterWikt>{{ cite web
|title=crater, In: ''Wiktionary''
|publisher=Wikimedia Foundation, Inc
|location=San Francisco, California
|month=October 16,
|year=2012
|url=http://en.wiktionary.org/wiki/crater
|accessdate=2013-02-15 }}</ref> is called a '''crater'''.

"'''Secondary craters''' are impact craters formed by the ejecta that was thrown out of a larger crater. They sometimes form radial crater chains."<ref name=SecondaryCrater>{{ cite web
|title=Secondary crater, In: ''Wikipedia''
|publisher=Wikimedia Foundation, Inc
|location=San Francisco, California
|month=March 1,
|year=2013
|url=http://en.wikipedia.org/wiki/Secondary_crater
|accessdate=2013-03-31[[Image:Mount Mazama eruption timeline.PNG|thumb|right|200px|Example of the formation of a caldera, the pictures show Mount Mazama's eruption timeline. Credit: .]]
A "cataclysm [may] have affected the entire inner Solar System ... [when] numerous main-belt asteroids ... were driven onto high-velocity and highly eccentric orbits by the effects of the late migration of the giant planets."<ref name=Marchi>{{ cite journal
|author=S. Marchi, W. F. Bottke, B. A. Cohen, K. Wünnemann, D. A. Kring, H. Y. McSween, M. C. De Sanctis, D. P. O’Brien, P. Schenk, C. A. Raymond & C. T. Russell
|title=High-velocity collisions from the lunar cataclysm recorded in asteroidal meteorites
|journal=Nature Geoscience
|month=March
|year=2013
|volume=6
|issue=4
|pages=303-7
|url=http://www.nature.com/ngeo/journal/v6/n4/full/ngeo1769.html
|arxiv=
|bibcode=
|doi=10.1038/ngeo1769
|pmid=
|pdf=
|accessdate=2013-03-29 }}</ref>

The sequence of figures depict a likely model for caldera collapse.

"A collapse is triggered by the emptying of the magma chamber beneath the volcano, usually as the result of a large volcanic eruption. If enough magma is ejected, the emptied chamber is unable to support the weight of the ''volcanic edifice'' above it. A roughly circular fracture, the ''ring fault'', develops around the edge of the chamber. Ring fractures serve as feeders for fault intrusions which are also known as ring dykes. Secondary volcanic vents may form above the ring fracture. As the magma chamber empties, the center of the volcano within the ring fracture begins to collapse. The collapse may occur as the result of a single cataclysmic eruption, or it may occur in stages as the result of a series of eruptions. The total area that collapses may be hundreds or thousands of square kilometers."<ref name=Caldera/>

Catenae "are thought to have been formed by the impact of a body that was broken up by tidal forces into a string of smaller objects following roughly the same orbit. An example of such a tidally disrupted body that was observed prior to its impact on [[Jupiter]] is Comet Shoemaker-Levy 9."<ref name=CraterChain/>

Catenae "on [[Mars]], represent chains of collapse pits associated with grabens (see, for example, the Tithoniae Catenae near Tithonium Chasma)."<ref name=CraterChain/>

"Crater chains seen on the [[Moon]] often radiate from larger craters, and in such cases are thought to be either caused by secondary impacts of the larger crater's ejecta or by volcanic venting activity along a rift.<ref name=Apollo>{{ cite web
|url=http://www.hq.nasa.gov/office/pao/History/SP-362/ch5.3.htm
|title=Apollo over  the Moon - Chapter 5: Craters
|accessdate=2008-02-03 }}</ref>"<ref name=CraterChain/>
{{clear}}

=Entities=
[[Image:Vulkanbombeneinschlag.png|thumb|right|200px|A volcanic bomb has deformed the rock strata. Credit: [[:de:User:Drucker03|Drucker03]].]]
'''Def.'''
# the "study of rock layers and the layering process [of] stratification"<ref name=StratigraphyWikt>{{ cite web
|title=stratigraphy, In: ''Wiktionary''
|publisher=Wikimedia Foundation, Inc
|location=San Francisco, California
|month=October 8,
|year=2013
|url=https://en.wiktionary.org/wiki/stratigraphy
|accessdate=2013-10-18 }}</ref> or
# "the layering of deposits, with newer remains overlaying older ones, forming a chronology of the site"<ref name=StratigraphyWikt/>

is called '''stratigraphy'''.

'''Def.''' "the process leading to the formation or deposition of layers, especially of sedimentary rocks"<ref name=StratificationWikt>{{ cite web
|title=stratification, In: ''Wiktionary''
|publisher=Wikimedia Foundation, Inc
|location=San Francisco, California
|month=June 19,
|year=2013
|url=https://en.wiktionary.org/wiki/stratification
|accessdate=2013-10-18 }}</ref> is called '''stratification'''.

'''Def.'''
# one "of several parallel horizontal layers of material arranged one on top of another",<ref name=StratumWikt>{{ cite web
|title=stratum, In: ''Wiktionary''
|publisher=Wikimedia Foundation, Inc
|location=San Francisco, California
|month=October 6,
|year=2013
|url=https://en.wiktionary.org/wiki/stratum
|accessdate=2013-10-18 }}</ref>
# a "layer of sedimentary rock having approximately the same composition throughout",<ref name=StratumWikt/> or
# any "of the regions of the atmosphere, such as the stratosphere, that occur as layers"<ref name=StratumWikt/>

is called a '''stratum''', plural '''strata'''.

Natural bombs may produce impact craters and deform rock strata.

"There is no correlation between n (the exponent for the change in particle diameter) and any of the other entities, which shows that n-values cannot be used as an index of maturation of a soil."<ref name=Jordan>{{ cite journal
|author=J.L. Jordan, J.R. Walton, D. Heymann, & S. Lakatos
|title=The Rim of North Ray Crater: A Relatively Young Regolith
|journal=Abstracts of the Lunar and Planetary Science Conference
|month=March
|year=1974
|volume=5
|issue=03
|pages=388
|url=http://adsabs.harvard.edu/abs/1974LPI.....5..388J
|arxiv=
|bibcode=1974LPI.....5..388J
|doi=
|pmid=
|pdf=
|accessdate=2013-10-18 }}</ref>

: <math> C_D = S (D/D_0)^{-n},</math>

where <math>C_D</math> is change in particle diameter, <math>S</math> is the constant of surface area rate of change, <math>D</math> is the measured particle diameter in the soil, <math>D_0</math> is the initial particle diameter for all samples, and <math>n</math> is the exponent.
{{clear}}

=Sources=
[[Image:Mount Tambora Volcano, Sumbawa Island, Indonesia.jpg|thumb|right|200px|This detailed astronaut photograph depicts the summit caldera of the Mount Tambora. Credit: NASA ISS Expedition 20 crew.]]
[[Image:Santa Ana Volcano.USAF.C-130.3.jpg|right|thumb|200px|The crater in Santa Ana Volcano is photographed from a United States Air Force C-130 Hercules flying above El Salvador. Credit: .]]
[[Image:Karthala volcano-Comoros.jpg|thumb|left|200px|The view is into Karthala volcano crater in November 2006 at the solidified lava lake Credit: alKomor.com.]]
[[Image:SP Crater.jpg|thumb|right|200px|S P Crater is a cinder cone volcano in the San Francisco volcanic field. Credit: .]]
The second image at right is a "detailed astronaut photograph [that] depicts the summit caldera of the volcano. The huge caldera—6 kilometers (3.7 miles) in diameter and 1,100 meters (3,609 feet) deep—formed when Tambora’s estimated 4,000-meter- (13,123-foot) high peak was removed, and the magma chamber below emptied during the April 10 eruption. Today the crater floor is occupied by an ephemeral freshwater lake, recent sedimentary deposits, and minor lava flows and domes from the nineteenth and twentieth centuries. Layered tephra deposits are visible along the northwestern crater rim. Active fumaroles, or steam vents, still exist in the caldera."<ref name=Wiscombe>{{ cite web
|author=Warren Wiscombe
|title=Mount Tambora Volcano, Sumbawa Island, Indonesia
|publisher=NASA Earth Observatory
|location=
|month=July 19,
|year=2009
|url=http://earthobservatory.nasa.gov/IOTD/view.php?id=39412
|pdf=
|accessdate=2013-03-30 }}</ref>

"On April 10, 1815, the Tambora Volcano produced the largest eruption in recorded history. An estimated 150 cubic kilometers (36 cubic miles) of tephra—exploded rock and ash—resulted, with ash from the eruption recognized at least 1,300 kilometers (808 miles) away to the northwest. While the April 10 eruption was catastrophic, historical records and geological analysis of eruption deposits indicate that the volcano had been active between 1812 and 1815. Enough ash was put into the atmosphere from the April 10 eruption to reduce incident sunlight on the Earth’s surface, causing global cooling, which resulted in the 1816 “year without a summer.”"<ref name=Wiscombe/>

At right is the crater in Santa Ana Volcano is photographed from a United States Air Force C-130 Hercules flying above El Salvador.

“A '''volcanic crater''' is a circular depression in the ground caused by volcanic activity.<ref name=Physical>{{ cite web
|url=http://www.physicalgeography.net/physgeoglos/c.html
|title=Glossary of Terms: C
|publisher=physicalgeography.net
|accessdate=2008-04-12}}</ref> It is typically a basin, circular in form within which occurs a vent (or vents) from which magma erupts as gases, lava, and ejecta. A crater can be of large dimensions, and sometimes of great depth. During certain types of climactic eruptions, the volcano's magma chamber may empty enough for an area above it to subside, forming what may appear to be a crater but is actually known as a caldera.”<ref name=VolcanicCrater>{{ cite web
|title=Volcanic Crater, In: ''Wikipedia''
|publisher=Wikimedia Foundation, Inc
|location=San Francisco, California
|month=June 10,
|year=2012
|url=http://en.wikipedia.org/wiki/Volcanic_crater
|accessdate=2012-06-12 }}</ref>

"In the majority of typical volcanoes, the crater is situated atop the mountain formed from the erupted volcanic deposits such as lava flows and tephra. Volcanoes that terminate in such a '''summit crater''' are usually of a conical form. Other volcanic craters may be found on the flanks of volcanoes, and these are commonly referred to as '''flank craters'''. Some volcanic craters may fill either fully or partially with rain and/or melted snow, forming a crater lake."<ref name=VolcanicCrater/>

The second image at right shows a solidified lava lake that composes the floor of the Karthala volcano crater.

“Phreatic eruptions typically include steam and rock fragments; the inclusion of lava is unusual. The temperature of the fragments can range from cold to incandescent. If molten material is included, the term phreato-magmatic may be used. These eruptions occasionally create broad, low-relief craters called ''maars''.”<ref name=PhreaticEruption>{{ cite web
|title=Phreatic eruption, In: ''Wikipedia''
|publisher=Wikimedia Foundation, Inc
|location=San Francisco, California
|month=May 7,
|year=2012
|url=http://en.wikipedia.org/wiki/Phreatic_eruption
|accessdate=2012-06-12 }}</ref>

"'''S P Crater''' is a cinder cone volcano in the San Francisco volcanic field, {{convert|25|mi|km|0}} north of Flagstaff, Arizona.<ref name=Priest>{{ cite web
| author = Susan S. Priest, Wendell A. Duffield, Karen Malis-Clark, James W. Hendley II, and Peter H. Stauffer
| title = The San Francisco Volcanic Field, Arizona: USGS Fact Sheet 017-01
| publisher = United States Geological Survey
| date = 2001-12-21
| url = http://geopubs.wr.usgs.gov/fact-sheet/fs017-01/
| accessdate = 2008-09-02 }}</ref> It is surrounded by several other cinder cones which are older and more eroded. It is a striking feature on the local landscape, with a well-defined lava flow that extends for {{convert|7|km|mi|1|sp=us}} to the north.<ref name=Lopes>{{ cite book
| author = Rosaly Lopes
| title = The Volcano Adventure Guide
| publisher = Cambridge University Press
| date = 2005-02-07
| pages = 153
| url = http://books.google.com/?id=eRqrEwvIvKoC&pg=PA153&lpg=PA153&dq=SP+Crater
| isbn = 978-0-521-55453-4 }}</ref>"<ref name=SPCrater>{{ cite web
|title=S P Crater, In: ''Wikipedia''
|publisher=Wikimedia Foundation, Inc
|location=San Francisco, California
|month=January 25,
|year=2013
|url=http://en.wikipedia.org/wiki/S_P_Crater
|accessdate=2013-03-31 }}</ref>

"S P Crater is a 820 foot high cinder cone of basaltic andesite. The cone is capped by an agglutinate rim that helps to protect its structure. A lava flow extends to the north of the cone for ~7&nbsp;km and originated from the same vent.<ref name=ulrich/> Some workers consider the lava flow to have slightly predated the cinder cone because of geochemical data that suggests the flow is more silica rich than the cinders and based on the observation that the cone overlaps the lava flow and shows no sign of deformation.<ref name=ulrich>{{ cite book
|author=Ulrich, G E
|title=SP Mountain cinder cone and lava flow, northern Arizona
|publisher=Geological Society of American Centennial Field Guide – Rocky Mountain Section
|year=1987
|pages=385–8 }}</ref> However, there is some debate about the relationship between the cone and flow as it is not uncommon to form cinder cones during the early phase of an eruption as a magma degasses, and then to have lava push through the side of a cone during a late phase of eruption."<ref name=SPCrater/>

"K/Ar dates on the lava are ~ 70 ka,<ref name=Basksi>{{cite journal
|author=Basksi  A, K
|title=K-Ar study of the S.P. flow
|journal=Canadian Journal of Earth Sciences
|year=1974
|pages=1350–1356
|volume=11 }}</ref> but are considered unreliable because of excess Ar<ref name=Duffield>{{ cite journal
|author=Duffield, Wendell A; Riggs, Nancy; Kaufman, Darrell; Champion, Duane; Fenton, Cassandra; Forman, Steven; McIntosh, William; Hereford, Richard; Plescia, Jeffrey; Ort, Michael
|title=Multiple constraints on the age of a Pleistocene lava dam across the Little Colorado River at Grand Falls, Arizona
|journal=Geological Society of America Bulletin
|volume=118
|issue=3-4
|pages=421-9
|year= 2006 }}</ref> and the un-weathered young appearance of the cone."<ref name=SPCrater/>

"Independently of other criteria the distribution of the KIT boundary ejecta predicts that the Chicxulub crater is the K/T source crater."<ref name=Hildebrand>{{ cite journal
|author=A.R. Hildebrand, J.A. Stansberry
|title=K/T boundary ejecta distribution predicts size and location of Chicxulub crater
|journal=Abstracts of the Lunar and Planetary Science Conference
|month=March
|year=1992
|volume=23
|issue=03
|pages=537
|url=http://adsabs.harvard.edu/full/1992LPI....23..537H
|arxiv=
|bibcode=1992LPI....23..537H
|doi=
|pmid=
|pdf=
|accessdate=2013-10-18 }}</ref>

"In agreement with many authors (Pal et al., 1982; Klein and Middleton, 1984; Blum et al., 1992), we therefore exclude meteoritic and lunar material as sources for the <sup>10</sup>Be in the Australasian tektites, and, by a short extension, for virtually all the other atoms in the tektites."<ref name=Ma>{{ cite journal
|author=P. Ma, K. Aggrey, C. Tonzola, C. Schnabel, P. de Nicola, G.F. Herzog, J.T. Wasson, B.P. Glass, L. Brown, F. Tera, R. Middleton, J. Klein
|title=Beryllium-10 in Australasian tektites: constraints on the location of the source crater
|journal=Geochimica et Cosmochimica Acta
|month=October
|year=2004
|volume=68
|issue=19
|pages=3883-96
|url=http://www.sciencedirect.com/science/article/pii/S0016703704002741
|arxiv=
|bibcode=
|doi=
|pmid=
|pdf=
|accessdate=2013-10-18 }}</ref>
{{clear}}

=Objects=
[[Image:Mare Imbrium-Apollo17.jpg|thumb|200px|right|Mare Imbrium (foreground) is peppered with secondary craters from the impact that formed Copernicus crater (upper center). Credit: NASA.]]
'''Def.''' "[a] hemispherical pit ... [a] basinlike opening or mouth ... about which a cone is often built up ... any large roughly circular depression or hole"<ref name=CraterWikt>{{ cite web
|title=crater, In: ''Wiktionary''
|publisher=Wikimedia Foundation, Inc
|location=San Francisco, California
|month=October 16,
|year=2012
|url=http://en.wiktionary.org/wiki/crater
|accessdate=2013-02-15 }}</ref> is called a '''crater'''.

"'''Secondary craters''' are impact craters formed by the ejecta that was thrown out of a larger crater. They sometimes form radial crater chains."<ref name=SecondaryCrater>{{ cite web
|title=Secondary crater, In: ''Wikipedia''
|publisher=Wikimedia Foundation, Inc
|location=San Francisco, California
|month=March 1,
|year=2013
|url=http://en.wikipedia.org/wiki/Secondary_crater
|accessdate=2013-03-31 }}</ref>

"The present paper deals with the problem of estimating the flux of objects large enough to produce impact craters on earth."<ref name=Shoemaker>{{ cite journal
|author=E. M. Shoemaker
|title=Astronomically observable crater-forming projectiles, In: 'Impact and Explosion Cratering: Planetary and terrestrial implications''
|publisher=Pergamon Press, Inc.
|location=New York
|month=
|year=1977
|volume=
|issue=
|pages=617-28
|url=http://adsabs.harvard.edu/abs/1977iecp.symp..617S
|arxiv=
|bibcode=
|doi=
|pmid=
|pdf=
|accessdate=2013-10-18 }}</ref>

"Phoebe is a densely cratered object. Cumulative numbers of craters, between 100 m and 100 km diameter, per unit area, define a steep-sloped curve (Fig. 5). Crater densities approach those seen on other heavily cratered objects (15, 16)."<ref name=Porco>{{ cite journal
|author=C. C. Porco1, E. Baker, J. Barbara, K. Beurle, A. Brahic, J. A. Burns, S. Charnoz, N. Cooper, D. D. Dawson, A. D. Del Genio, T. Denk, L. Dones, U. Dyudina, M. W. Evans, B. Giese, K. Grazier, P. Helfenstein, A. P. Ingersoll, R. A. Jacobson, T. V. Johnson, A. McEwen, C. D. Murray, G. Neukum, W. M. Owen, J. Perry, T. Roatsch, J. Spitale, S. Squyres, P. C. Thomas, M. Tiscareno, E. Turtle, A. R. Vasavada, J. Veverka, R. Wagner, R. West
|title=Cassini imaging science: Initial results on Phoebe and Iapetus
|journal=Science
|month=February
|year=2005
|volume=307
|issue=5713
|pages=1237-42
|url=http://www.sciencemag.org/content/307/5713/1237.short
|arxiv=
|bibcode=
|doi=
|pmid=
|pdf=
|accessdate=2013-10-18 }}</ref>
{{clear}}

=Strong forces=
[[Image:La Cumbre - ISS.JPG|thumb|right|200px|This satellite photograph is of the summit caldera on Fernandina Island in the Galapagos archipelago. Credit: .]]
[[Image:Pinatubo92pinatubo caldera crater lake.jpg|thumb|left|200px|Mt.Pinatubo is in the Philippines. Credit: .]]
[[Image:Crater lake oregon.jpg|thumb|left|200px|Crater Lake, Oregon, formed around 5,680 BC. Credit: .]]
(contracted; show full)|url=http://www.benthamscience.com/open/toaaj/articles/V004/SI0162TOAAJ/185TOAAJ.pdf
|arxiv=
|bibcode=
|doi=
|pmid=
|pdf=
|accessdate=2013-10-18 }}</ref>

{{clear}}

=Weak forces=

=Continuum=⏎
“A superbolt, more powerful than an ordinary lightning bolt, struck a cornfield near Leland, Illinois, leaving a crater one foot deep, and breaking windows in homes almost a mile away.<ref name=Burt>Christopher C. Burt, ''Extreme Weather: A Guide & Record Book'' (W. W. Norton & Company, 2007), p149</ref>”<ref name=April1959>{{ cite web
|title=April 1959, In: ''Wikipedia''
|publisher=Wikimedia Foundation, Inc
|location=San Francisco, California
|month=June 9,
|year=2012
|url=http://en.wikipedia.org/wiki/April_1959
|accessdate=2012-06-12 }}</ref>
{{clear}}

=Weak forces=

=Continuum=

"Croft [3] called moat craters anomalous pit craters and also suggested a continuum between moat craters, craters, and palimpsests, even though morphometrically they appeared to be distinct."<ref name=Lucchitta>{{ cite journal
|author=B.K. Lucchitta and H.M. Ferguson
|title=Ganymede: "Moat" Craters Compared with Palimpsests and Basins
|journal=Abstracts of the Lunar and Planetary Science Conference
|month=March
|year=1988
|volume=19
|issue=03
|pages=701
|url=http://adsabs.harvard.edu/full/1988LPI....19..701L
|arxiv=
|bibcode=1988LPI....19..701L
|doi=
|pmid=
|pdf=
|accessdate=2013-10-18 }}</ref>

=Emissions=
[[Image:Toba zoom.jpg|thumb|left|200px|Landsat captures an image of Lake Toba, on the island of Sumatra, Indonesia. Credit: .]]
[[Image:Whetstone Sulky 001.jpg|thumb|right|200px|Rubble mound, or dome, formed by the Operation Whetstone Sulky explosion. Credit: .]]
[[Image:Callisto Har PIA01054.jpg|thumb|right|200px|This is a Galileo image of Hár. Credit: NASA.]]
[[Image:Panum Crater.jpg|thumb|right|200px|This is an image of Panum Crater with its central lava dome, Mono Craters, California, USA. Credit: USGS.]]⏎
A resurgent dome forms the island of Samosir within the caldera of Lake Toba. It is 100 km/62 mi long and 30 km/19 mi wide, a caldera of the world's largest class.

"When the material above the explosion is solid rock, then a mound may be formed by broken rock that has a greater volume. This type of mound has been called "retarc", "crater" spelled backwards.<ref name=nwa_effects>{{ cite web|last=Sublette|first=Carey|title=The Effects of Underground Explosions|url=http://nuclearweaponarchive.org/Library/Effects/UndergroundEffects.html|work=Nuclear Weapon Archive|accessdate=21 June 2011}}</ref>"<ref name=SubsidenceCrater/>
{{clear}}

=Absorptions=
[[Image:Sedan Plowshare Crater.jpg|thumb|right|200px|This image shows the crater created by the Sedan shallow underground nuclear test explosion. Credit: National Nuclear Security Administration, Federal Government of the United States.]]
[[Image:Stylised crater.png|thumb|left|200px|This diagram depicts a stylized cross-section of a crater formed by a below-ground explosion. Credit: [[w:User:JBel|JBel]].]]
[[Image:Huron King Crater.jpg|thumb|right|200px|Post-shot subsidence crater and Operation Tinderbox Huron King test chamber is from an explosion of less than 20 TNT equivalent kilotons (1980). Credit: ⏎
“'''Hár''' is a crater on [[Jupiter]]'s moon [[Callisto]]. Its name is one of the many names of Odin, the supreme god in Norse mythology. This is an example of a central dome impact crater.<ref name=Greeley>{{ cite journal
| last=Greeley| first=R.| coauthors=Klemaszewski, J.E.;Wagner L.; et al.
| title=Galileo views of the geology of Callisto
|journal=Planetary and Space Science
| year=2000
| volume=48
| issue=9
| pages=829–853
| doi=10.1016/S0032-0633(00)00050-7
|bibcode=2000P&SS...48..829G}}</ref>”<ref name=HarCrater>{{ cite web
|title=Hár (crater), In: ''Wikipedia''
|publisher=Wikimedia Foundation, Inc
|location=San Francisco, California
|month=February 20,
|year=2012
|url=http://en.wikipedia.org/wiki/Hár_(crater)
|accessdate=2012-06-12 }}</ref>

"The name Panum Crater refers to a crater surrounded by [an] ejecta ring, with a dome in the middle. At Panum Crater the dome didn't completely fill the crater or overrun the ring (as often happens) providing an opportunity to explore all three structures."<ref name=Sieh>{{ cite web
|author=Kerry Sieh
|title=Long Valley Caldera Field Guide - Panum Crater
|publisher=USGS
|location=
|month=January 31,
|year=2012
|url=http://volcanoes.usgs.gov/volcanoes/long_valley/long_valley_sub_page_17.html
|pdf=
|accessdate=2013-03-30 }}</ref>

"At Panum, a pyroclastic eruption (new magma explosively fragmented into the air) followed the phreatic (steam) eruption. During a pyroclastic eruption, the gas within the magma continues to expand and escape as the magma is thrown into the air and cools. The resulting deposits included ash (particles <2mm in size) and pumice. The pumice is frothy preserving the frozen gas bubbles."<ref name=Sieh/>

"The ejecta ring is made up of small bits of pumice, ash, obsidian fragments, and well-rounded granitic pebbles (which were part of the surrounding rock and not formed during the eruption) that were ejected during the final explosive stage of the eruption."<ref name=Sieh/>

"The central lava dome was erupted from degassed material and is made up of pumice and obsidian of the same composition. The difference between the two has to do with gas escaping as the magma cooled. The magma that created the dome had dissolved gas in it, like a bottle of seltzer water. As the magma rose towards the surface where there was less pressure on it than at depth, the gas expanded producing the holes (bubbles) you see in the pumice. The magma that remained pressurized while it cooled quickly or that had already lost its gas, formed the obsidian."<ref name=Sieh/>

"Flow banding containing both obsidian and pumice is common at Panum Crater. Another common texture, called breadcrust, can also be seen in the dome. Breadcrust textures form when the inside of a cooling rock is still hot with gas escaping from it while the outside surface has already cooled. As the gas expands from the inside, the outside surface cracks to allow the gas to escape."<ref name=Sieh/>
{{clear}}

=Absorptions=
[[Image:Sedan Plowshare Crater.jpg|thumb|right|200px|This image shows the crater created by the Sedan shallow underground nuclear test explosion. Credit: National Nuclear Security Administration, Federal Government of the United States.]]
[[Image:Stylised crater.png|thumb|left|200px|This diagram depicts a stylized cross-section of a crater formed by a below-ground explosion. Credit: [[w:User:JBel|JBel]].]]
[[Image:Huron King Crater.jpg|thumb|right|200px|Post-shot subsidence crater and Operation Tinderbox Huron King test chamber is from an explosion of less than 20 TNT equivalent kilotons (1980). Credit: .]]
[[Image:Callisto Tindr PIA01657.jpg|right|thumb|The image shows a Galileo image of Tindr. Credit: .]]
[[Image:Elura.png|right|thumb|200px|Sub-Level Caving Subsidence reaches surface at the Ridgeway underground mine. Credit: Rolinator.]]
[[Image:Škocjan, Divača - naravni most med Veliko in Malo dolino.jpg|thumb|left|200px|This is the gorge where the Reka River disappears underground. Credit: [http://www.flickr.com/people/53197929@N00 Dennis Tang] from London, UK.]]
[[Image:Unterflöz 12.jpg|thumb|right|200px|A photograph shows a collapsed mine tunnel to the west of № VI Conow adit. Credit: Bernd Triller, Bergamt Stralsund; Recherche:[[commons:User:Berginspektor|Berginspektor]].]]
[[Image:Makhtesh Hazera.jpg|thumb|left|200px|This image is an oblique aerial photo of Makhtesh Hazera. Credit: N. Fruchter, A. Matmon, Y. Avni, and D. Fink.]]
The image at right shows the crater created by the Sedan shallow underground nuclear test explosion.

At left is a stylised cross-section of a crater formed by a below-ground explosion.

“A crater is formed by an explosive event through the displacement and ejection of material from the ground. It is typically bowl-shaped. High pressure gas and pressure waves are responsible for the creation of the crater by three processes
# plastic deformation of the ground
(contracted; show full)

"When a drilling oil well encounters high-pressured gas which cannot be contained either by the weight of the drilling mud or by blow-out preventers, the resulting violent eruption can create a large crater which can swallow up a drilling rig. This phenomenon is called "cratering" in oil field slang."<ref name=SubsidenceCrater/>

{{clear}}

=Bands=

=Background=

=Impact crater⏎
An image of Tindr is shown at right. It is a pit crater.

“'''Tindr''' is a crater on [[Jupiter]]'s moon Callisto. It is named after one of the ancestors of Ottar in Norse mythology. This is an example of a central pit impact crater.<ref name=Greeley>{{ cite journal
| author=R. Greeley, J.E. Klemaszewski, L. Wagner
| title=Galileo views of the geology of Callisto
|journal=Planetary and Space Science
| year=2000
| volume=48
| pages=829–53
| doi=10.1016/S0032-0633(00)00050-7
| bibcode=2000P&SS...48..829G
| issue=9 }}</ref>”<ref name=TindrCrater>{{ cite web
|title=Tindr (crater), In: ''Wikipedia''
|publisher=Wikimedia Foundation, Inc
|location=San Francisco, California
|month=February 20,
|year=2012
|url=http://en.wikipedia.org/wiki/Tindr_(crater)
|accessdate=2012-06-12 }}</ref>

Removal of material and rock beneath a surface may result in a collapse of material above into the cavern below.

"In accordance with its definition, a makhtesh (Hebrew for "mortar" or "crater"; plural, makhteshim) is an erosion structure incised into an anticline and having a single drainage system with one outlet."<ref name=Insarov>{{ cite journal
|author=Gregory Insarov & Irina Insarova
|title=The lichens of calcareous rocks in the Central Negev, Israel
|journal=Israel Journal of Plant Sciences
|month=
|year=1995
|volume=43
|issue=1
|pages=53-62
|url=http://www.tandfonline.com/doi/abs/10.1080/07929978.1995.10676590
|arxiv=
|bibcode=
|doi=10.1080/07929978.1995.10676590
|pmid=
|pdf=
|accessdate=2013-10-16 }}</ref>

"Erosional craters (Makhtesh) were formed by truncation and erosion of several of these anticlinal crests."<ref name=Fruchter>{{ cite journal
|author=N. Fruchter, A. Matmon, Y. Avni, D. Fink
|title=Revealing sediment sources, mixing, and transport during erosional crater evolution in the hyperarid Negev Desert, Israel
|journal=Geomorphology
|month=November 15,
|year=2011
|volume=134
|issue=3-4
|pages=363-77
|url=http://www.sciencedirect.com/science/article/pii/S0169555X11003564
|arxiv=
|bibcode=
|doi=
|pmid=
|pdf=
|accessdate=2013-10-16 }}</ref>

At lower left, the image is an oblique aerial photo of Makhtesh Hazera. The Makhtesh drainage divide is outlined by a bold black line, with both of its constituent features (the anticlinal valley and the Upper Basin) located.<ref name=Fruchter/>
{{clear}}

=Bands=
[[Image:Tycho crater on the Moon.jpg|thumb|right|200px|The prominent impact crater is Tycho on the Moon. Credit: NASA.]]
[[Image:Impact movie.ogg|thumb|left|200px|A laboratory simulation of an impact event and crater formation is shown. Credit: .]]
[[Image:Craterstructure.gif|thumb|right|200px|Impact crater structure is diagrammed. Credit: .]]
[[Image:Wells creek shatter cones 2.JPG|thumb|left|200px|Close-up of shatter cones developed in fine grained dolomite from the Wells Creek crater, USA, are shown. Credit: .]]
[[Image:USGS Decorah crater.jpg|thumb|right|200px|U.S. Geological Survey aerial electromagnetic resistivity map of the Decorah crater has been produced. Credit: .]]
[[Image:Crater 24.jpg|thumb|right|200px|The image shows a crater produced by missile impact in silty sand and sandy silt, oblique view. Credit: US Army.]]⏎
“In the broadest sense, the term '''impact crater''' can be applied to any depression, natural or manmade, resulting from the high velocity impact of a projectile with a larger body. In most common usage, the term is used for the approximately circular depression in the surface of a planet, moon or other solid body in the [[Solar System]], formed by the hypervelocity impact of a smaller body with the surface. In contrast to volcanic craters, which result from explosion or internal collapse,<ref name=Basaltic>Basaltic Volcanism Study Project. (1981). Basaltic Volcanism on the Terrestrial Planets; Pergamon Press, Inc: New York, p. 746. http://articles.adsabs.harvard.edu//full/book/bvtp./1981//0000746.000.html.</ref> impact craters typically have raised rims and floors that are lower in elevation than the surrounding terrain.<ref name=Consolmagno>Consolmagno, G.J.; Schaefer, M.W. (1994). ''Worlds Apart: A Textbook in Planetary Sciences;'' Prentice Hall: Englewood Cliffs, NJ, p.56.</ref> Impact craters range from small, simple, bowl-shaped depressions to large, complex, multi-ringed impact basins. Meteor Crater is perhaps the best-known example of a small impact crater on the Earth.”<ref name=ImpactCrater>{{ cite web
|title=Impact crater, In: ''Wikipedia''
|publisher=Wikimedia Foundation, Inc
|location=San Francisco, California
|month=May 13,
|year=2012
|url=http://en.wikipedia.org/wiki/Impact_crater
|accessdate=2012-06-12 }}</ref>
{{clear}}

=Hypervelocity impact craters=
[[Image:USGS Decorah crater.jpg|thumb|right|200px|U.S. Geological Survey aerial electromagnetic resistivity map of the Decorah crater has been produced. Credit: .]]
"Impact cratering involves high velocity collisions between solid objects, typically much greater than the velocity of sound in those objects. Such hyper-velocity impacts produce physical effects such as melting and vaporization that do not occur in familiar sub-sonic collisions. On Earth, ignoring the slowing effects of travel through the atmosphere, the lowest impact velocity with an object from space is equal to the gravitational escape velocity of about 11&nbsp;km/s. The fastest impacts occur (contracted; show full)

"The shale is an ideal target and provides the electrical contrast that allows us to clearly image the geometry and internal structure of the crater," Bedrosian said.<ref name=Koontz/>

{{clear}}

=Central dome=
[[Image:Callisto Har PIA01054.jpg|thumb|right|200px|This is a Galileo image of Hár. Credit: NASA.]]
“'''Hár''' is a crater on [[Jupiter]]'s moon [[Callisto]]. Its name is one of the many names of Odin, the supreme god in Norse mythology. This is an example of a central dome impact crater.<ref name=Greeley>{{ cite journal
| last=Greeley| first=R.| coauthors=Klemaszewski, J.E.;Wagner L.; et al.
| title=Galileo views of the geology of Callisto
|journal=Planetary and Space Science
| year=2000
| volume=48
| issue=9
| pages=829–853
| doi=10.1016/S0032-0633(00)00050-7
|bibcode=2000P&SS...48..829G}}</ref>”<ref name=HarCrater>{{ cite web
|title=Hár (crater), In: ''Wikipedia''
|publisher=Wikimedia Foundation, Inc
|location=San Francisco, California
|month=February 20,
|year=2012
|url=http://en.wikipedia.org/wiki/Hár_(crater)
|accessdate=2012-06-12 }}</ref>
{{clear}}

=Oblique hypervelocity impact craters=
[[Image:Crater 24.jpg|thumb|right|200px|The image shows a crater produced by missile impact in silty sand and sandy silt, oblique view. Credit: US Army.]]
The image at the right shows a crater produced by missile impact in silty sand and sandy silt photographed in an oblique view. The "[m]issile traveled along an oblique trajectory, 45.8° from the horizontal with a kinetic energy of 25.1 x 10<sup>14</sup> ergs. The crater, about 6 metres across, and ejecta have bilateral symmetry because of the oblique trajectory. [The t]race of path of [the] missile is shown by [the] arrow. Small depressions in foreground are footprints."<ref name=M(contracted; show full); ergs. The oblique impacts produce craters 2 to 10 m across with morphologies and ejecta that are bilaterally symmetrical with respect to the plane of the missile trajectory. Rims are high and the amount of ejecta large in down-trajectory and lateral directions, whereas rims are low to nonexistent and ejecta thin to absent up-trajectory. Symmetry development and modifications of the symmetry are a function of target material, local topography, and angle of impact."<ref name=Moore/>
{{clear}}

=
Lightning crater=

“A superbolt, more powerful than an ordinary lightning bolt, struck a cornfield near Leland, Illinois, leaving a crater one foot deep, and breaking windows in homes almost a mile away.<ref name=Burt>Christopher C. Burt, ''Extreme Weather: A Guide & Record Book'' (W. W. Norton & Company, 2007), p149</ref>”<ref name=April1959>{{ cite web
|title=April 1959, In: ''Wikipedia''
|publisher=Wikimedia Foundation, Inc
|location=San Francisco, California
|month=June 9,
|year=2012
|url=http://en.wikipedia.org/wiki/April_1959
|accessdate=2012-06-12 }}</ref>

=Pit crater=
[[Image:Callisto Tindr PIA01657.jpg|right|thumb|The image shows a Galileo image of Tindr. Credit: .]]
An image of Tindr is shown at right. It is a pit crater.

“'''Tindr''' is a crater on [[Jupiter]]'s moon Callisto. It is named after one of the ancestors of Ottar in Norse mythology. This is an example of a central pit impact crater.<ref name=Greeley>{{ cite journal
| author=R. Greeley, J.E. Klemaszewski, L. Wagner
| title=Galileo views of the geology of Callisto
|journal=Planetary and Space Science
| year=2000
| volume=48
| pages=829–53
| doi=10.1016/S0032-0633(00)00050-7
| bibcode=2000P&SS...48..829G
| issue=9 }}</ref>”<ref name=TindrCrater>{{ cite web
|title=Tindr (crater), In: ''Wikipedia''
|publisher=Wikimedia Foundation, Inc
|location=San Francisco, California
|month=February 20,
|year=2012
|url=http://en.wikipedia.org/wiki/Tindr_(crater)
|accessdate=2012-06-12 }}</ref>
{{clear}}

=Subsidence crater=
[[Image:Elura.png|right|thumb|200px|Sub-Level Caving Subsidence reaches surface at the Ridgeway underground mine. Credit: Rolinator.]]
[[Image:Škocjan, Divača - naravni most med Veliko in Malo dolino.jpg|thumb|left|200px|This is the gorge where the Reka River disappears underground. Credit: [http://www.flickr.com/people/53197929@N00 Dennis Tang] from London, UK.]]
[[Image:Unterflöz 12.jpg|thumb|right|200px|A photograph shows a collapsed mine tunnel to the west of № VI Conow adit. Credit: Bernd Triller, Bergamt Stralsund; Recherche:[[commons:User:Berginspektor|Berginspektor]].]]
[[Image:Makhtesh Hazera.jpg|thumb|left|200px|This image is an oblique aerial photo of Makhtesh Hazera. Credit: N. Fruchter, A. Matmon, Y. Avni, and D. Fink.]]
Removal of material and rock beneath a surface may result in a collapse of material above into the cavern below.

"In accordance with its definition, a makhtesh (Hebrew for "mortar" or "crater"; plural, makhteshim) is an erosion structure incised into an anticline and having a single drainage system with one outlet."<ref name=Insarov>{{ cite journal
|author=Gregory Insarov & Irina Insarova
|title=The lichens of calcareous rocks in the Central Negev, Israel
|journal=Israel Journal of Plant Sciences
|month=
|year=1995
|volume=43
|issue=1
|pages=53-62
|url=http://www.tandfonline.com/doi/abs/10.1080/07929978.1995.10676590
|arxiv=
|bibcode=
|doi=10.1080/07929978.1995.10676590
|pmid=
|pdf=
|accessdate=2013-10-16 }}</ref>

"Erosional craters (Makhtesh) were formed by truncation and erosion of several of these anticlinal crests."<ref name=Fruchter>{{ cite journal
|author=N. Fruchter, A. Matmon, Y. Avni, D. Fink
|title=Revealing sediment sources, mixing, and transport during erosional crater evolution in the hyperarid Negev Desert, Israel
|journal=Geomorphology
|month=November 15,
|year=2011
|volume=134
|issue=3-4
|pages=363-77
|url=http://www.sciencedirect.com/science/article/pii/S0169555X11003564
|arxiv=
|bibcode=
|doi=
|pmid=
|pdf=
|accessdate=2013-10-16 }}</ref>

At lower left, the image is an oblique aerial photo of Makhtesh Hazera. The Makhtesh drainage divide is outlined by a bold black line, with both of its constituent features (the anticlinal valley and the Upper Basin) located.<ref name=Fruchter/>
{{clear}}

=Volcanic craters=
[[Image:Santa Ana Volcano.USAF.C-130.3.jpg|right|thumb|200px|The crater in Santa Ana Volcano is photographed from a United States Air Force C-130 Hercules flying above El Salvador. Credit: .]]
[[Image:Karthala volcano-Comoros.jpg|thumb|left|200px|The view is into Karthala volcano crater in November 2006 at the solidified lava lake Credit: alKomor.com.]]
At right is the crater in Santa Ana Volcano is photographed from a United States Air Force C-130 Hercules flying above El Salvador.

“A '''volcanic crater''' is a circular depression in the ground caused by volcanic activity.<ref name=Physical>{{ cite web
|url=http://www.physicalgeography.net/physgeoglos/c.html
|title=Glossary of Terms: C
|publisher=physicalgeography.net
|accessdate=2008-04-12}}</ref> It is typically a basin, circular in form within which occurs a vent (or vents) from which magma erupts as gases, lava, and ejecta. A crater can be of large dimensions, and sometimes of great depth. During certain types of climactic eruptions, the volcano's magma chamber may empty enough for an area above it to subside, forming what may appear to be a crater but is actually known as a caldera.”<ref name=VolcanicCrater>{{ cite web
|title=Volcanic Crater, In: ''Wikipedia''
|publisher=Wikimedia Foundation, Inc
|location=San Francisco, California
|month=June 10,
|year=2012
|url=http://en.wikipedia.org/wiki/Volcanic_crater
|accessdate=2012-06-12 }}</ref>

"In the majority of typical volcanoes, the crater is situated atop the mountain formed from the erupted volcanic deposits such as lava flows and tephra. Volcanoes that terminate in such a '''summit crater''' are usually of a conical form. Other volcanic craters may be found on the flanks of volcanoes, and these are commonly referred to as '''flank craters'''. Some volcanic craters may fill either fully or partially with rain and/or melted snow, forming a crater lake."<ref name=VolcanicCrater/>

The second image at right shows a solidified lava lake that composes the floor of the Karthala volcano crater.

“Phreatic eruptions typically include steam and rock fragments; the inclusion of lava is unusual. The temperature of the fragments can range from cold to incandescent. If molten material is included, the term phreato-magmatic may be used. These eruptions occasionally create broad, low-relief craters called ''maars''.”<ref name=PhreaticEruption>{{ cite web
|title=Phreatic eruption, In: ''Wikipedia''
|publisher=Wikimedia Foundation, Inc
|location=San Francisco, California
|month=May 7,
|year=2012
|url=http://en.wikipedia.org/wiki/Phreatic_eruption
|accessdate=2012-06-12 }}</ref>
{{clear}}

==Central lava dome==
[[Image:Panum Crater.jpg|thumb|right|200px|This is an image of Panum Crater with its central lava dome, Mono Craters, California, USA. Credit: USGS.]]
"The name Panum Crater refers to a crater surrounded by [an] ejecta ring, with a dome in the middle. At Panum Crater the dome didn't completely fill the crater or overrun the ring (as often happens) providing an opportunity to explore all three structures."<ref name=Sieh>{{ cite web
|author=Kerry Sieh
|title=Long Valley Caldera Field Guide - Panum Crater
|publisher=USGS
|location=
|month=January 31,
|year=2012
|url=http://volcanoes.usgs.gov/volcanoes/long_valley/long_valley_sub_page_17.html
|pdf=
|accessdate=2013-03-30 }}</ref>

"At Panum, a pyroclastic eruption (new magma explosively fragmented into the air) followed the phreatic (steam) eruption. During a pyroclastic eruption, the gas within the magma continues to expand and escape as the magma is thrown into the air and cools. The resulting deposits included ash (particles <2mm in size) and pumice. The pumice is frothy preserving the frozen gas bubbles."<ref name=Sieh/>

"The ejecta ring is made up of small bits of pumice, ash, obsidian fragments, and well-rounded granitic pebbles (which were part of the surrounding rock and not formed during the eruption) that were ejected during the final explosive stage of the eruption."<ref name=Sieh/>

"The central lava dome was erupted from degassed material and is made up of pumice and obsidian of the same composition. The difference between the two has to do with gas escaping as the magma cooled. The magma that created the dome had dissolved gas in it, like a bottle of seltzer water. As the magma rose towards the surface where there was less pressure on it than at depth, the gas expanded producing the holes (bubbles) you see in the pumice. The magma that remained pressurized while it cooled quickly or that had already lost its gas, formed the obsidian."<ref name=Sieh/>

"Flow banding containing both obsidian and pumice is common at Panum Crater. Another common texture, called breadcrust, can also be seen in the dome. Breadcrust textures form when the inside of a cooling rock is still hot with gas escaping from it while the outside surface has already cooled. As the gas expands from the inside, the outside surface cracks to allow the gas to escape."<ref name=Sieh/>
{{clear}}

==Cinder cone==
[[Image:SP Crater.jpg|thumb|right|200px|S P Crater is a cinder cone volcano in the San Francisco volcanic field. Credit: .]]
"'''S P Crater''' is a cinder cone volcano in the San Francisco volcanic field, {{convert|25|mi|km|0}} north of Flagstaff, Arizona.<ref name=Priest>{{ cite web
| author = Susan S. Priest, Wendell A. Duffield, Karen Malis-Clark, James W. Hendley II, and Peter H. Stauffer
| title = The San Francisco Volcanic Field, Arizona: USGS Fact Sheet 017-01
| publisher = United States Geological Survey
| date = 2001-12-21
| url = http://geopubs.wr.usgs.gov/fact-sheet/fs017-01/
| accessdate = 2008-09-02 }}</ref> It is surrounded by several other cinder cones which are older and more eroded. It is a striking feature on the local landscape, with a well-defined lava flow that extends for {{convert|7|km|mi|1|sp=us}} to the north.<ref name=Lopes>{{ cite book
| author = Rosaly Lopes
| title = The Volcano Adventure Guide
| publisher = Cambridge University Press
| date = 2005-02-07
| pages = 153
| url = http://books.google.com/?id=eRqrEwvIvKoC&pg=PA153&lpg=PA153&dq=SP+Crater
| isbn = 978-0-521-55453-4 }}</ref>"<ref name=SPCrater>{{ cite web
|title=S P Crater, In: ''Wikipedia''
|publisher=Wikimedia Foundation, Inc
|location=San Francisco, California
|month=January 25,
|year=2013
|url=http://en.wikipedia.org/wiki/S_P_Crater
|accessdate=2013-03-31 }}</ref>

"S P Crater is a 820 foot high cinder cone of basaltic andesite. The cone is capped by an agglutinate rim that helps to protect its structure. A lava flow extends to the north of the cone for ~7&nbsp;km and originated from the same vent.<ref name=ulrich/> Some workers consider the lava flow to have slightly predated the cinder cone because of geochemical data that suggests the flow is more silica rich than the cinders and based on the observation that the cone overlaps the lava flow and shows no sign of deformation.<ref name=ulrich>{{ cite book
|author=Ulrich, G E
|title=SP Mountain cinder cone and lava flow, northern Arizona
|publisher=Geological Society of American Centennial Field Guide – Rocky Mountain Section
|year=1987
|pages=385–8 }}</ref> However, there is some debate about the relationship between the cone and flow as it is not uncommon to form cinder cones during the early phase of an eruption as a magma degasses, and then to have lava push through the side of a cone during a late phase of eruption."<ref name=SPCrater/>

"K/Ar dates on the lava are ~ 70 ka,<ref name=Basksi>{{cite journal
|author=Basksi  A, K
|title=K-Ar study of the S.P. flow
|journal=Canadian Journal of Earth Sciences
|year=1974
|pages=1350–1356
|volume=11 }}</ref> but are considered unreliable because of excess Ar<ref name=Duffield>{{ cite journal
|author=Duffield, Wendell A; Riggs, Nancy; Kaufman, Darrell; Champion, Duane; Fenton, Cassandra; Forman, Steven; McIntosh, William; Hereford, Richard; Plescia, Jeffrey; Ort, Michael
|title=Multiple constraints on the age of a Pleistocene lava dam across the Little Colorado River at Grand Falls, Arizona
|journal=Geological Society of America Bulletin
|volume=118
|issue=3-4
|pages=421-9
|year= 2006 }}</ref> and the un-weathered young appearance of the cone."<ref name=SPCrater/>
{{clear}}Background=

=Meteors=

=Cosmic rays=

=Neutrals=

=Subatomics=

=Neutrons=

=Protons=

=Mesons=

=Beta particles=

=Electrons=

=Positrons=

=Muons=

=Neutrinos=

=Gamma rays=

=X-rays=

=Ultraviolets=

=Opticals=

=Visuals=

=Violets=

=Blues=

=Cyans=

=Greens=

=Yellows=

=Oranges=

=Reds=

=Infrareds=

=Submillimeters=

=Microwaves=

=Radars=

=Radios=

=Superluminals=

=Plasma objects=

=Gaseous objects=

=Liquid objects=

=Rocky objects=

=Astrochemistry=

=Hydrogen=

=Helium=

=Lithium=

=Beryllium=

=Boron=

=Carbon=

=Nitrogen=

=Oxygen=

=Fluorine=

=Neon=

=Ions=

=Compounds=

=Alloys=

=Atmospheres=

=Materials=

=Meteorites=

=Shelters=

=Spectroscopy=

=Spectrometers=

=Planetary astronomy=

=Mercury=
[[Image:Mercury Globe-MESSENGER mosaic centered at 0degN-0degE.jpg|thumb|right|200px|This is a composite image of Mercury taken by the MESSENGER probe. Credit: .]]
[[Image:Mariner 10.jpg|thumb|left|200px|Mariner&nbsp;10 is the first probe to visit the innermost planet (1974–75). Credit: .]]
{{multiple image
| align = left
| direction = horizontal
(contracted; show full)|location=San Francisco, California
|month=November 15,
|year=2012
|url=http://en.wikipedia.org/wiki/Deep_Impact_(spacecraft)
|accessdate=2012-12-05 }}</ref>
{{clear}}

=
Theoretical cratering=
[[Image:Mount Mazama eruption timeline.PNG|thumb|right|200px|Example of the formation of a caldera, the pictures show Mount Mazama's eruption timeline. Credit: .]]
A "cataclysm [may] have affected the entire inner Solar System ... [when] numerous main-belt asteroids ... were driven onto high-velocity and highly eccentric orbits by the effects of the late migration of the giant planets."<ref name=Marchi>{{ cite journal
|author=S. Marchi, W. F. Bottke, B. A. Cohen, K. Wünnemann, D. A. Kring, H. Y. McSween, M. C. De Sanctis, D. P. O’Brien, P. Schenk, C. A. Raymond & C. T. Russell
|title=High-velocity collisions from the lunar cataclysm recorded in asteroidal meteorites
|journal=Nature Geoscience
|month=March
|year=2013
|volume=6
|issue=4
|pages=303-7
|url=http://www.nature.com/ngeo/journal/v6/n4/full/ngeo1769.html
|arxiv=
|bibcode=
|doi=10.1038/ngeo1769
|pmid=
|pdf=
|accessdate=2013-03-29 }}</ref>

The sequence of figures depict a likely model for caldera collapse.

"A collapse is triggered by the emptying of the magma chamber beneath the volcano, usually as the result of a large volcanic eruption. If enough magma is ejected, the emptied chamber is unable to support the weight of the ''volcanic edifice'' above it. A roughly circular fracture, the ''ring fault'', develops around the edge of the chamber. Ring fractures serve as feeders for fault intrusions which are also known as ring dykes. Secondary volcanic vents may form above the ring fracture. As the magma chamber empties, the center of the volcano within the ring fracture begins to collapse. The collapse may occur as the result of a single cataclysmic eruption, or it may occur in stages as the result of a series of eruptions. The total area that collapses may be hundreds or thousands of square kilometers."<ref name=Caldera/>

Catenae "are thought to have been formed by the impact of a body that was broken up by tidal forces into a string of smaller objects following roughly the same orbit. An example of such a tidally disrupted body that was observed prior to its impact on [[Jupiter]] is Comet Shoemaker-Levy 9."<ref name=CraterChain/>

Catenae "on [[Mars]], represent chains of collapse pits associated with grabens (see, for example, the Tithoniae Catenae near Tithonium Chasma)."<ref name=CraterChain/>

"Crater chains seen on the [[Moon]] often radiate from larger craters, and in such cases are thought to be either caused by secondary impacts of the larger crater's ejecta or by volcanic venting activity along a rift.<ref name=Apollo>{{ cite web
|url=http://www.hq.nasa.gov/office/pao/History/SP-362/ch5.3.htm
|title=Apollo over  the Moon - Chapter 5: Craters
|accessdate=2008-02-03 }}</ref>"<ref name=CraterChain/>
{{clear}}

=Entities=

"There is no correlation between n (the exponent for the change in particle diameter) and any of the other entities, which shows that n-values cannot be used as an index of maturation of a soil."<ref name=Jordan>{{ cite journal
|author=J.L. Jordan, J.R. Walton, D. Heymann, & S. Lakatos
|title=The Rim of North Ray Crater: A Relatively Young Regolith
|journal=Abstracts of the Lunar and Planetary Science Conference
|month=March
|year=1974
|volume=5
|issue=03
|pages=388
|url=http://adsabs.harvard.edu/abs/1974LPI.....5..388J
|arxiv=
|bibcode=1974LPI.....5..388J
|doi=
|pmid=
|pdf=
|accessdate=2013-10-18 }}</ref>

: <math> C_D = S (D/D_0)^{-n},</math>

where <math>C_D</math> is change in particle diameter, <math>S</math> is the constant of surface area rate of change, <math>D</math> is the measured particle diameter in the soil, <math>D_0</math> is the initial particle diameter for all samples, and <math>n</math> is the exponent.

=Sources=

"Independently of other criteria the distribution of the KIT boundary ejecta predicts that the Chicxulub crater is the K/T source crater."<ref name=Hildebrand>{{ cite journal
|author=A.R. Hildebrand, J.A. Stansberry
|title=K/T boundary ejecta distribution predicts size and location of Chicxulub crater
|journal=Abstracts of the Lunar and Planetary Science Conference
|month=March
|year=1992
|volume=23
|issue=03
|pages=537
|url=http://adsabs.harvard.edu/full/1992LPI....23..537H
|arxiv=
|bibcode=1992LPI....23..537H
|doi=
|pmid=
|pdf=
|accessdate=2013-10-18 }}</ref>

"In agreement with many authors (Pal et al., 1982; Klein and Middleton, 1984; Blum et al., 1992), we therefore exclude meteoritic and lunar material as sources for the <sup>10</sup>Be in the Australasian tektites, and, by a short extension, for virtually all the other atoms in the tektites."<ref name=Ma>{{ cite journal
|author=P. Ma, K. Aggrey, C. Tonzola, C. Schnabel, P. de Nicola, G.F. Herzog, J.T. Wasson, B.P. Glass, L. Brown, F. Tera, R. Middleton, J. Klein
|title=Beryllium-10 in Australasian tektites: constraints on the location of the source crater
|journal=Geochimica et Cosmochimica Acta
|month=October
|year=2004
|volume=68
|issue=19
|pages=3883-96
|url=http://www.sciencedirect.com/science/article/pii/S0016703704002741
|arxiv=
|bibcode=
|doi=
|pmid=
|pdf=
|accessdate=2013-10-18 }}</ref>

=Objects=

"The present paper deals with the problem of estimating the flux of objects large enough to produce impact craters on earth."<ref name=Shoemaker>{{ cite journal
|author=E. M. Shoemaker
|title=Astronomically observable crater-forming projectiles, In: 'Impact and Explosion Cratering: Planetary and terrestrial implications''
|publisher=Pergamon Press, Inc.
|location=New York
|month=
|year=1977
|volume=
|issue=
|pages=617-28
|url=http://adsabs.harvard.edu/abs/1977iecp.symp..617S
|arxiv=
|bibcode=
|doi=
|pmid=
|pdf=
|accessdate=2013-10-18 }}</ref>

"Phoebe is a densely cratered object. Cumulative numbers of craters, between 100 m and 100 km diameter, per unit area, define a steep-sloped curve (Fig. 5). Crater densities approach those seen on other heavily cratered objects (15, 16)."<ref name=Porco>{{ cite journal
|author=C. C. Porco1, E. Baker, J. Barbara, K. Beurle, A. Brahic, J. A. Burns, S. Charnoz, N. Cooper, D. D. Dawson, A. D. Del Genio, T. Denk, L. Dones, U. Dyudina, M. W. Evans, B. Giese, K. Grazier, P. Helfenstein, A. P. Ingersoll, R. A. Jacobson, T. V. Johnson, A. McEwen, C. D. Murray, G. Neukum, W. M. Owen, J. Perry, T. Roatsch, J. Spitale, S. Squyres, P. C. Thomas, M. Tiscareno, E. Turtle, A. R. Vasavada, J. Veverka, R. Wagner, R. West
|title=Cassini imaging science: Initial results on Phoebe and Iapetus
|journal=Science
|month=February
|year=2005
|volume=307
|issue=5713
|pages=1237-42
|url=http://www.sciencemag.org/content/307/5713/1237.short
|arxiv=
|bibcode=
|doi=
|pmid=
|pdf=
|accessdate=2013-10-18 }}</ref>

=Continua=

"Croft [3] called moat craters anomalous pit craters and also suggested a continuum between moat craters, craters, and palimpsests, even though morphometrically they appeared to be distinct."<ref name=Lucchitta>{{ cite journal
|author=B.K. Lucchitta and H.M. Ferguson
|title=Ganymede: "Moat" Craters Compared with Palimpsests and Basins
|journal=Abstracts of the Lunar and Planetary Science Conference
|month=March
|year=1988
|volume=19
|issue=03
|pages=701
|url=http://adsabs.harvard.edu/full/1988LPI....19..701L
|arxiv=
|bibcode=1988LPI....19..701L
|doi=
|pmid=
|pdf=
|accessdate=2013-10-18 }}</ref>

=Crater emissions=

=Crater absorptions=

=Bands=

=Background=

=Ejection meteors=

=Cosmic rays=

=Neutrons=

=Protons=

=Electrons=

=Positrons=

=Neutrinos=

=Gamma rays=

=X-rays=

=Ultraviolet=

=Optical=

=Visual=

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=Red=

=Infrared=

=Submillimeter=

=Radio=

=SuperluminalsGeography=

=Locations on Earth=

=Extreme locations=

=History=

=Prehistory=

=Ancient history=

=Early history=

=Classical history=

=Recent history=

=Mathematics=

=Physics=

=Science=

=Technology=

=See also=
{{div col|colwidth=12em}}
* [[Meteor astronomy]]
* [[Meteorites]]
{{Div col end}}

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