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Re: Isotopic Evidence for the K - T Impactor and Its Type

Stanley Friesen <sarima@ix.netcom.com> wrote

>And I
>have certainly heard suggestions that at least one mid-Cenozoic crater is
>known of comparable magnitude.

Recent work showed that the Chicxulub crater was about 100 km is diameter.
The prominent 175-190 km feature is actually a fault scarp. Thus its size is
comparable to both Popigai (100 km) and Chesapeake Bay (85 km) impact
craters (both 35-36 mya) which were not associated with any extinction event.

Morgan J, Warner M & The Chicxulub Working Group, Size and morphology
of the Chicxulub impact crater, Nature 1997; 390: 472-76 

Melosh H J, Multi-ringed revelation, Nature 1997; 390: 439-40

Stoffler D, Claeys P, Earth rocked by combination punch, Nature 1997; 388:

Kerr R A, Chesapeake Bay Impact Crater Confirmed, Science 1995; 269:

Gautam Majumdar                 gautam@majumdar.demon.co.uk