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Re: deep water = less ejecta?




----- Original Message ----- From: "MICHAEL HABIB" <habib@jhmi.edu>
To: <dinosaur@usc.edu>
Sent: Sunday, January 27, 2008 12:12 PM
Subject: Re: deep water = less ejecta?



>My reading of this is that they infer deep water from the shallow nature >of the crater--meaning (I think) that the water >absorbed enough energy >to blunt the force on the ocean floor.

It could also mean that the floor filled and rose more rapidly immediately after impact than it would have in a terrestrial setting, leaving a more shallow depression post-impact.

In any case, if the crater is shallow it follows that less ejecta was blown out (right?)

Maybe, but not necessarily. Even if it is true, that would only refer to the melted rock ejecta; the rest would be water (which probably isn't much better for the global ecosystems), and the total ejected mass would likely be similar.


If the water/rock ratio was appreciably different this should have a different effect than previously believed. For example, heat >energy in water vapor would have a more local effect...at least versus the re-entry of solids globally.

The effect might be different, but I'm not sure we have reason to think it would be more local (perhaps fewer actual forest fires and more general broiling?). The heat energy in the water vapor would still be transferred to the atmosphere, and thanks to the high heat capacity of water, it would be able to travel further before completely unloading its heat energy. So, I think we need more information before assessing if this would make a major difference in the global scale.


Cheers,

--Mike


Michael Habib, M.S.
PhD. Candidate
Center for Functional Anatomy and Evolution
Johns Hopkins School of Medicine
1830 E. Monument Street
Baltimore, MD 21205
(443) 280 0181
habib@jhmi.edu