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Re: Mesozoic terrain (long)



Jeffrey Willson wrote:
> 
> I did not say what dinos "could not do".
> 
> I believe I was careful to say de Camp "opined" a hypothesis, about which
> ramifications "seemed" to me to follow.
> 
> It seems to me that two possibilities which follow from the info I posted are
> 
> A) de Camp doesn't know beans.

Hi, JimC here again.  The only time I ever thought Sprague didn't know
beans, was when he told James Gifford I was doing a biography of Robert
Heinlein (I'm not, and wasn't).  The de Camps are absolutely brilliant;
both of them.  I've never caught de Camp in a technical error and am not
sure he knows how to make one, but that isn't really my point here. 
Over grazing might move a range from year to year, but erosion won't. 
The most rapid erosion I've seen was along the Mississippi River, where
a strip of bank ten or fifteen yards wide and a couple hundred yards
long might go in a single splash, but that doesn't happen very often -
perhaps once or twice a year in unstable areas - once in ten years in
stable reaches. On the other hand, island formation and bar movements
can be more rapid.  The second most severe erosion in my experience was
along Tillatoba Creek in north central Mississippi where head cutting
was lowering the channel bottom about ten feet and the overfall was
moving upstream a few hundred feet a year.  Neither of these events
would have the least effect on annual range changes, but could easily
require that new crossing points be found.  I like the idea of predator
concentration at terrain transition points.  That sort of thought is
what I find most fascinating about this list.   Thanks.

> If we mean that the "preferred ranges" were actually "moving" from year to
> year due to erosion, I'd call this "serious" if not catastrophic. 

This wouldn't happen, except perhaps from severe wind driven 'dust bowl'
events like the one that caused the 'Oakie' migrations of the 30's, or
very rare natural dam (or ice dam) collapses that catastrophicly release
lakes into the downstream channel.

> (Whats the back-of-the-envelope math on the energy needed to raise a 20,000
> kilo dinosaur 10 meters?).

10*20,000=200,000 kilogram-meters of work.  Power required depends on
how quickly they do it.
> 
> Jeffrey Willson <jwillson@harper.cc.il.us>