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Jewels and Joules

September 26, 2012

The technology for dating an impact crater has gotten better – what probably should be done is to recalibrate all the ages in a standard way at some point. Of interest is when major impacts might have been close in time. Specifically, in this case, Chesapeake Bay and Popigai. There is also what is probably an impressive impact crater offshore slightly north near Toms River New Jersey. More of about that next post. Part of the problem here is impactors failed to use MySpace to give a date, decade, millenium or much else when they arrived. If Chesapeake Bay and Popigai were 500,000 years apart that’s quite different than 5 days, 5 months or 5 years.

http://impact.ese.ic.ac.uk/ImpactEffects/ is recommended

Here’s a table of calculations for a high iron (4000 kilograms per cubic meter) “rock” 20 kilometers in diameter hitting Earth. [note: 20 km would be larger than any known impactor.] The columns are velocity (meters per second); energy in joules; crater diameter in miles assuming 15% of energy, cubic meters of rock ejected, melt thickness in meters and melt volume in cubic meters.

For reference, the Hiroshima atomic bomb explosion was about 67 times 10 to the 12. Depending on velocity, density and size as well as a few other factors, several thousand Hiroshimas at once.

 

 

 

 

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From → Impact craters

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