Hi list, Nice shatter cones Mark...
Here is some photos of shatter cone boulders at Keurusselkä impact structure found last November. Unfortunately, they are not in my collection, since they are too big boulders: http://www.somerikko.net/impacts/keurusselka.html see also our Keurusselkä LPSC-abstract (made in hurry): http://www.lpi.usra.edu/meetings/lpsc2004/pdf/1619.pdf Shatter cone photos can be seen also in my collection pages (click impactites): http://www.somerikko.net/old/geo/col/col.htm As for hint where to look at: I have shatter cones from: Beaverhead, Charlevoix, Dellen, Flynn Creek (weak), Gardnos, Glover Bluff, Kara, Karikkoselkä, Kentland, Keurusselkä (no photos yet), Lappajärvi, Marquez Dome, Middlesboro (weak), Paasselkä, Ries, Rochechouart, Rubielos de la Cérida, Saarijärvi, Serpent Mound, Siljan, Steinheim, Sudbury, Suvasvesi structures, Suvasvesi S, Sääksjärvi, Vredefort and Wells Creek. Jarmo Moilanen www.somerikko.net [EMAIL PROTECTED] MARK BOSTICK kirjoitti 20.02.2004 kello 03:57: > Hello List, > Shatter cones are one of my favorite types of meteorite impactite. Found > around large impact craters, called astroblemes (from Greek astron, > blema, > meaning "star wound"). Shatter cones have a distinctively patterned > structure that are formed in the rock by a large impacting object. Often > conically-shaped, these rocks have close-spaced "grooves" or "lines" > that > radiate outward from the apex. The apex, or point, of the stone points > towards the impact area. I've always thought of shatter cones as a sound > fossil. An Earth rock that has recorded the sound wave of the a large > object from outer space announcing its arrival to earth. > The following are photos showing most of the shatter cones in my > personal > collection. A couple I wanted to show were cut and you could see a > cross of > shatter cones in layers. Usually, you can break a shatter cone, and > create > two shatter cones. Some times something pretty, some times not. The > three > bottom photos show a shatter cone many of you might find of > interest. This > was found by Robert Szep, who told me he found it along the S.W. > portion of > Wanapitei Lake, about 30 yards from the shoreline. This was sold to > me as a > "double shatter cone", something that I have seen reported in several > books. According to Szep both ends, or apex were pointed in the correct > fashion for it to be a double shatter cone (each towards one of the > craters). However, I understand that sometimes, the sound-shock wave > from > the Sudbury impact, appeared to bounce in the target rock, leaving a > crinkle. The examples I have seen have been only in photos and are very > large, not on a small scale such as this specimen. The shatter cone > breaks > at almost a 90 degree angle. > Any impact cratering, physics or sound expert out there have any > opinion on > this rock? I have always felt sorry for the stone, hit by two > meteorites. > > Beaverhead Shatter cone. (Not large for the local, but for most > collections > it is). Almost perfect cone shape. > http://www.meteoritearticles.com/files/Beaverhead_Shattercone.jpg > http://www.meteoritearticles.com/files/Beaverhead_Shattercone_on_side.jpg > > Kentland Shatter cone > http://www.meteoritearticles.com/files/Kentland_Shattercone.jpg > > Rochochouart Shatter cone > http://www.meteoritearticles.com/files/Shattercone_Roch.jpg > > Sheinheim Shatter Cone. The second one is "cute". > http://www.meteoritearticles.com/files/Steinheim_Shattercone.jpg > http://www.meteoritearticles.com/files/Steinheim_Shattercone_nice.jpg > > Wells Creek Shatter Cones > First photo is positive side, second is negative side > http://www.meteoritearticles.com/files/Shattercone_Wellcreek_1.jpg > http://www.meteoritearticles.com/files/Shattercone_Wellcreek_b.jpg > Shattercone with nice "horsetailing", second photo is closeup > http://www.meteoritearticles.com/files/wells_Creek_Shattercone.jpg > http://www.meteoritearticles.com/files/Wells_Creek_Shattercone_foxtailingjpg > > > Serpent Mound Shatter Cones > http://www.meteoritearticles.com/files/Sijin_Shattercone.jpg > > Siljan Shatter cone > http://www.meteoritearticles.com/files/Serphant_Monnd_Shattercone.jpg > > Sudbury Shatter cones > 3.5 kilogram Sudbury Shatter cone. > http://www.meteoritearticles.com/files/Sudbury_Shattercone_3.5kg_side.jpg > http://www.meteoritearticles.com/files/Sudbury_Shattercone_3.5kg.jpg > > Large flat Sudbury Shatter cone. > http://www.meteoritearticles.com/files/Sudbury_flat_shattercone_side_1.jpg > http://www.meteoritearticles.com/files/Sudbury_flat_shattercone_side2.jpg > > A Sudbury and Winnipeg double shatter cone. > http://www.meteoritearticles.com/files/Sudbury_Winnipeg_Shattercone.jpg > http://www.meteoritearticles.com/files/Sudbury_Winnipeg_Shattercone_Side_1.j > pg > http://www.meteoritearticles.com/files/Sudbury_Winnipeg_Shattercone_Side_1.j > pg > > > > Please visit, www.MeteoriteArticles.com, a free on-line archive of > meteor > and meteorite articles. .............................................................. 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