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Re: Sauropods vs. Gravity



Although I don't agree with Colin's thoughts on possible past gravity
fluctuations, I feel obligated to point out that lower gravity in the past does
not imply that the earth was physically smaller then, or that it is more massive
now.  For example, a phase change in the core, mantle, or crust could cause the
earth to be smaller in diameter now, which would result in greater gravity at 
the
surface (I don't believe to have been the case).  For a given mass, a smaller
radius in the past would have resulted in greater surface gravity then.  If the
earth were smaller in the past, and less massive, the surface gravity could have
been either less or more, depending upon how much smaller and how much less
mass.  Planets smaller than the earth can have greater surface gravity, even 
with
less mass than the earth, just as they can have lower surface gravity with more
mass.

Jim

Richard W Travsky wrote:

> On Sun, 3 Mar 2002, Matthew Bonnan wrote:

> > However, if earth's gravity did fluctuate, that would
> > mean that it would have been physically smaller in the past and has become
> > larger and more massive now.