Re: paleonet non-green plants and Mistaken Point

[apparent elk <kaplanp@xxxxxxxxx>]

On Tue, 8 Oct 2002, Rod Savidge wrote:
 This rate-of-sinking argument seems reasonable.  It also seems plausible to
 me that it might take some time, following shock-wave killing of
 sea-surface organisms, before initially upward ejected ashes would begin to
 settle on the sea surface.   There must be measurements on this in relation
 to recent eruptions??   Anyway, I'm sure it could be determined experimentally.

I'm not so sure about the rate-of-sinking argument ("high-density tuff
particles will settle more quickly than low-density ediacarans"). Sinking
velocity for tuff particles will be dominated by viscous drag due to their
tiny sizes; they will settle out *after* particles that are large enough to
be dominated by inertial drag -- even if those larger particles (here,
Ediacarans) are somewhat less dense. We all know how long ash can stay
suspended in the atmosphere without falling, and the case for water would
be even more suspensory. A child's balloon, on the other hand, has
extremely low density but will not stay in the air more than a few minutes
(assuming no helium is involved).

My apologies if I've missed a context-specific and cogent argument about
the Mistaken Point scenario. Just trying to catch a potential taphonomic
red herring before it's fried...

 Peter A. Kaplan * Peter A. Kaplan * Peter A. Kaplan * Peter A. Kaplan
 * Ph. D. Candidate * Department of Geology * University of Michigan *

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