Life On Mars..?

[Keith A Henderson]

Damon suggests....
>
> > I don't know about the bacteria issue...there is certainly some
> > bacteria/life in Antarctica, although buried in the ice there's
> > probably very little.  But I wouldn't count this out as a contamination
> > problem.
>
> Then again, Antarctica was most likely not frozen a few million years
> ago, as 1) the world was a bit warmer and 2) Antarctica was not, um,
> antarctic.

Exactly *how* many million years??  Current belief here (Byrd Polar) is that
the ice sheet has been roughly nearly constant in size/thickness for perhaps
2.5 million years, and began to form somewhere around 30 million years ago.  In
between, there were perhaps numerous partial deglaciations of a significant
degree, but no evidence to suggest Antarctica became completely ice free.
Other research groups (namely URI and Maine) argue that Antarctica is very
stable, and has existed in near its present form since the Miocene.

Interestingly though, land ice is a very rare occurrence when you look at the
entire history of the Earth....all 4.5 billion years of it.  I don't know
exactly what the percentage of time is that experienced ice sheet development,
but it has to be less than, say, 5% of the time.  So, the issue of
anthropogenic global warming seems pretty odd when you look at the really big
picture.  Coal swamps in Antarctica in the Cretaceous period is a little hard
to imagine (and Antarctica was only a *little* bit farther north then).  So
this is *still* an ice age in reality, just not in Ohio anymore... :)

> Of course, one could also assume that these meteorites buried
> in the ice must have actually landed in pre-existing ice.  Otherwise
> they'd be buried under the ice and the land underneath that, in which
> case the scientists probably wouldn't have found them in the first place.
> :)

Not sure exactly what point you're making here...but if it was believed to have
landed 100,000 years ago (I saw that date here, dunno if it's true), it
certainly landed on ice.  And if it became entrained in the ice cap, it would
not likely ever make it's way into the subglacial till, unless the ice cap
melted, or the meteorite had already travelled all the way to the margin...(ice
caps flow downhill just like any other 'fluid' medium).  And as I mentioned
before, there are those places, mainly in the region of the Trans-Antarctic
Mountains, where nunataks and ice-buried mountains create an 'ice-upwelling'
zone, where a shear surface is created and old, deep Antarctic ice is brought
to the surface, along with a whole bunch of debris, some from the underlying
bed, along with more than a few meteorites.  Pictures of these from the air are
interesting....these areas are sometimes 'dirty' enough that they're called
supraglacial moraines.

So anyway, it would actually be possible (I think) for a meteorite that landed
on the land surface of Antarctica, to then be overridden by ice, and then
brought to the surface in this manner....it just wouldn't likely have happened
in the last 3 million years.  And the lifetime of ice in Antarctica is (in a
practical sense) probably only a few hundred thousand years, with the exception
of a few rare remnants pasted against the sides of mountains here and there.

Keith H. (FAA)

P.S.  And no, if all the world's land ice melted, sea level would not rise so
much as to flood most of the land...it would rise approximately 80 meters.  So
Kevin Costner would not need to grow gills...