Shatter cone: Difference between revisions

→‎Morphology: the word striae should not be used, with reference added http://www.impact-structures.com/impact-rocks-impactites/the-shatter-cone-page/
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(→‎Morphology: the word striae should not be used, with reference added http://www.impact-structures.com/impact-rocks-impactites/the-shatter-cone-page/)
 
==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]]''). However the word "striae" should not be used to described shatter cones as it is described as "misleading".<ref>http://www.impact-structures.com/impact-rocks-impactites/the-shatter-cone-page/</ref> 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 shattercone in the world (more than 10 metres in length) is located at the [[Slate Islands (Ontario)|Slate Islands]] in [http://www.terracebay.ca Terrace Bay], Ontario, Canada. The azimuths of the cones's axes typically radiate outwards from the point of impact, with the cones pointing upwards and toward the center of the impact crater, although the orientation of some of the rocks have been changed by post-cratering geological processes at the site.
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