"jonathan" wrote in message
...

"Doug..." wrote in message
...
In article ,
says...

snip

Actually, if there is a little soil movement activity, or if the
spheres
are moderately dense, the movement of sand could be enough to keep
them on
top. Try placing various sized objects in a container and shaking it-
the
smallest objects will sift to the bottom and the larger ones will rise
to
the top. These spheres could be going through a similar process,
keeping
them on the upper layer of regolith.
I am of the idea that the spheres are from one of three possible
origins:
a) an impact in mud and the thin air and low gravity allow them to
solidify and fall back to the ground. The spheres might have been
heated in
this sort of event, hardening them.
b) accretion from some geological process, perhaps through the
presence
of water.
c) biological activity.

If a) is true, then you would expect that these spheres might be
very
old, when it was more likely that water was extant on the surface.
But,
permafrost theories also say that there might be occasional torrents
when
impacts or other events release the water bound up in permafrost.


If they're ancient I wouldn't expect the spheres to show a diversity
of condition, some badly broken, some very pristine. The Spirit
site looks ancient, this just doesn't to me.

Am I missing something here? What pictures are you using to come to that
conclusion? If you look at this very close-up image, you will see spheres
in a range of conditions, from almostr pristine to pitted and broken:

http://marsrovers.jpl.nasa.gov/galle...P2933M1M1.HTML



If b) is true, you might expect a broader range of sizes, although
some
type of sorting process might also be at work. However, the look at
the
layering of the rocks and the fact that spheres are embedded
throughout
seems to indicate that they were present before the rock layer were
formed.
If true, and if the rock is sedimentary (as it appears to be) then it
leads
you to think that the spheres are resistant to the action of water and
from
an earlier period.
Of course, some suggest that the spheres might have formed inside
the
rock, but my gut feeling (not very scientific!) is that this should
lead to
various concentrations of these spheres through the rock, not the
sparse
concentration we see. In other words, some clusters of the spheres
should
occur if they were formed in the rock.


Isn't soil on earth built by repetitive biological cycles?

Most soils on the earth are formed from chemical and mechanical weathering:

http://enterprise.cc.uakron.edu/geol...weath.htm#summ

Wouldn't
we expect to see fossilized examples of the biology that built the
soil in the bedrock, sedimentary bedrock?

Why?



If c) is true, then we have found what we are after. I notice
that many
of the spheres have odd characteristics, such as "tapered" ends, or
small
depressions. Could these be traces of some structure that an original
organism had?


When I look at this pic I can't help thinking we're seeing an
entire life cycle. Smudges of formation, mature forms and
broken forms.


http://marsrovers.jpl.nasa.gov/galle...P2953M2M1.HTML


Hahahahahahaha!!! Sorry, I couldn't help but laugh. What you are looking
at are spheres in various stages of mechanical decomposition. They are
inorganic mineraloids, dude.


Another possibility is that some outcrop of mineral had crumbled
and
rolled downstream in the past, wearing away and producing smooth
"pebbles".
Note that this can also produce a sorting mechanism, as the movement
of
water and the mass and size of the stones could select out the ones in
a
narrow range of cross sections and masses. If true, we could expect
to find
other areas with lots of spheres of different diameter- larger or
smaller
overall.
Note that I do include the effects of water in most of my ideas.
Well,
enough rambling.



I really wish the rover would take a spin outside the crater to get
some good images of the surrounding field.

Have some patience. That is on the rover's agenda. They also plan to
travel to a much large crater that is much closer to Opportunity than the
crater that Spirit is trying to reach. I suspect Opportunity may actually
reach that crater before Spirit reaches its crater.

I live along the Florida everglades, it's a 40 mile wide river of grass
following the flow of mostly underground water. I can't help but think
the soil, spheres and smooth flowing terrain around Opportunity is a
result
of underground water or ice.

Well, there is certainly no evidence one way or another for that idea. If
you look at an image of the region, you will note that it is a large crater
that has been nearly completely filled with soil/sediment/regolith:

http://marsoweb.nas.nasa.gov/dataViz.../HematiteWest/

Also note that there are younger craters that have impacted this filled
region, which has in turn filled the older, much larger crater. This fact,
aside from the fact of the presence of hematite, and the flatness of the
terraine, is one of the reasons why this site was chosen for exploration.