Editing Shatter cone

{{short description|Geological feature in bedrock resulting from extreme mechanical shock}}
[[Image:Strahlenkalk.jpg|thumb|right|Shatter cone from the [[Steinheim crater|Steinheim Basin]] (type locality), Germany]]
[[File:Slate Islands Shattercone.JPG|thumb|right|Largest shatter cone registered, more than 9m in height, [[Slate Islands (Ontario)|Slate Islands]], Terrace Bay, Ontario, Canada]]
<!-- [[Image:Shatter-Cone_Ammonit.JPG|thumb|right|Strahlenkalk (shatter cone) within ammonite steinkern from the [[Steinheim crater|Steinheim Basin]] (type locality), Germany.]] -->
[[Image:Shattercone_Wengenhausen.JPG|thumb|right|Typical shatter cone from [[Nördlinger Ries|Ries impact crater]], Germany]]

'''Shatter cones''' are rare geological features that are only known to form in the [[bedrock]] beneath [[meteorite]] [[impact crater]]s or [[Underground nuclear weapons testing|underground nuclear explosions]]. They are evidence that the rock has been subjected to a [[Shock (mechanics)|shock]] with pressures in the range of {{convert|2-30|GPa|psi|abbr=on|lk=on}}.<ref name=French1998>{{cite book
 | author = French, B.M.
 | date = 1998
 | title = Traces of catastrophe
 | publisher = Lunar and Planetary Institute
 | url = http://www.lpi.usra.edu/publications/books/CB-954/CB-954.intro.html
 | access-date = 2007-05-20
 }}</ref><ref name=Sagy2004>{{cite journal
 |author      = Sagy, A.
 |author2     = Fineberg, J.
 |author3     = Reches, Z.
 |date        = 2004
 |title       = Shatter cones: Branched, rapid fractures formed by shock impact
 |journal     = Journal of Geophysical Research
 |volume      = 109
 |issue = B10
 |pages       = B10209
 |doi         = 10.1029/2004JB003016
 |bibcode     = 2004JGRB..10910209S
 |doi-access= free
 }}</ref><ref name=IFSG2005>{{Cite journal
 |last        = French
 |first       = Bevan M.
 |title       = Stalking the Wily Shatter Cone: A Critical Guide for Impact-Crater Hunters
 |journal     = Impacts in the Field
 |publisher   = [[Impact Field Studies Group]]
 |volume      = 2
 |issue       = Winter
 |pages       = s 3–10
 |date        = 2005
 |url         = http://web.eps.utk.edu/~faculty/ifsg_files/newsletter/Winter_2005.pdf
 |url-status     = dead
 |archive-url  = https://web.archive.org/web/20110720104913/http://web.eps.utk.edu/~faculty/ifsg_files/newsletter/Winter_2005.pdf
 |archive-date = 2011-07-20
}}</ref>

==Morphology==
Shatter cones have a distinctively conical shape that radiates from the top (''apex'') of the cones repeating cone-on-cone in large and small scales in the same sample. Sometimes they have more of a spoon shape on the side of a larger cone.<ref name=Sagy2004/>  In finer-grained rocks such as [[limestone]], they form an easily recognizable "horsetail" pattern with thin grooves (''[[wikt:stria|striae]]'').

Coarser grained rocks tend to yield less well developed shatter cones, which may be difficult to distinguish from other geological formations such as [[slickensides]].  Geologists have various theories of what causes shatter cones to form, including compression by the wave as it passes through the rock or tension as the rocks rebound after the pressure subsides.  The result is large and small branching fractures throughout the rocks.<ref name=French1998/><ref name=Sagy2004/><ref name=IFSG2005/>

Shatter cones can range in size from microscopic to several meters. The largest known shatter cone in the world (more than 10 metres in length) is located at the [[Slate Islands (Ontario)|Slate Islands]] in Terrace Bay, Ontario, Canada. The azimuths of the cones' axes typically radiate outwards from the point of impact, with the cones pointing upwards and toward the center of the impact crater, although the orientations of some of the rocks have been changed by post-cratering geological processes at the site.{{Cn|date=March 2021}}

==See also==
* [[Breccia]]
* [[Coesite]]
* [[Lechatelierite]]
* [[Shocked quartz]]
* [[Stishovite]]

==References==
{{Reflist}}

==Further reading==
* Baratoux, D.; Reimold, W.U. (2016). "The current state of knowledge about shatter cones: Introduction to the special issue", ''Meteoritics & Planetary Science'', Volume 51, Issue 8, Special Issue: Shatter Cones—Nature and Genesis, pages 1389–1434, {{doi-inline|10.1111/maps.12678}}

== External links ==
* {{Commons category inline|Shatter cones}}

{{Impact cratering on Earth}}

[[Category:Impact craters]]
[[Category:Impact geology]]
[[Category:Petrology]]