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Beaverhead
Gaetan wrote/a écrit:
> Diameter: 15km
Hello Leonard, Gaetan and List,
Slight correction concerning its d i a m e t e r, unless it has been
updated:
R.B. Hargraves, P.P. Christiansen, C.E. Cullicott, K.S. Deffeyes,
P.S.Fiske and S. Hougen, 1990, Shattercones and Shocked Rocks in SW
Montana: The Beaverhead Impact Structure, Geology 18, 832-834:
Estimated diameter is 60 km. Recently discovered shatter cones in
Paleozoic Belt rocks are spread over a 15 x 8 km area in SW Montana.
These same shatter cones were noted but not recognized as early as
1966 (B.K. Lucchitta, 1966, Ph.D. Diss. Penn. State Univ.).
C. Koeberl et al. (1991)Beaverhead Impact Structure - Geochemistry of
Impactites and Country Rock Samples (abs. in Meteoritics, 1991, vol. 26,
no. 4, p. 358):
The shatter cones point steeply upward and are abundant in sandstones of
the Belt Supergroup, covering an area of about > 100 km^2.
Can I now have a shattercone too, please? :-)
Best wishes and happy hunting,
Bernd
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