"OndaWeb" wrote in message ...
I wrote JPl some of this yesterday. Base on what Dr. Squires has said, it
seems clear the spherules are being exhumed out of the matrix of the bed
rock. But notice they are relatively scarce in the bed rock. But on the
surface, epically outside of the crater, they are plentiful, virtually
covering the entire surface.

Thus it seems that the bedrock, thought to underlie the entire plain in
Meridiani, must be filled with these spherules that are eventually
"released" as the bedrock is eroded by wind. Perhaps the bedrock becomes
the dust and sand of Mars. The spherules are left behind, at least in this
area, to blanket the floor (or they may be blown and rolled from somewher
uphill).

And it seems likely the spherules are the source of the hematite. According
to the "mineral map", wherever the spherules are, the hematite signature is
strong (at the rim of the crater, outside the crater, some places inside.)
Conversely the signature is weak where there are few spherules (in the
bedrock, where the spectra of the soil was taken, and most significantly,
where the airbags of the Lander squashed them into the soil).

It seems to me the easiest explanation is fine volcanic ash (maybe cemented
with some water from snows when the orbital eccentricity changes)is the bed
rock and the spherules are hematite rich condensed globules. So any
geologist know of a plausable process by which a volanic eruption would make
both ash and hematite rich spherules?

The rocks look for all the world like Archaean rhyolitic ignimbrites
(colour, platy parting and all). Spherules are characteristic;
coalesced pairs common.
http://users.indigo.net.au/don/pr/dogsballs.html (sometimes in
threes)
(The haematite would be unusual though. )

The spherules are a puzzle (to me). The spherule texture is little
different from that of the matrix.

df.



Roy Clymer
" George" wrote in message
. ..

"scrodchunk" wrote in message
om...
The spheroid particles in the bedrock look a lot like those in the
surface 'gravel' To me this suggests two likely things.

a) the spheroids in the rock were formed in the same
manner as those in the gravel

and more interestingly

b) a period of change occured where the planet changed from
a state much like the current state (with spheroids in the
gravel) into a state where sedimentary rock could form (such
as a prolonged period of moisture, which has then returned
to the current state.

That's pretty interesting, because if there were prolonged wet periods
on mars (ie before the atmosphere precipitated into icecaps) there was
probably time for such that sedimentary concretions could form,
rudimentary life could perhaps form too.

It would be interesting to give the rock a good whack though, and see
how solid it is.

Ross.

Unfortunately, the rovers left their rock hammers at home! And they call
these contraptions "geologists"? :-) I would add that the spherules in
the
soil apparently originated from the bedrock, as it too contains the same
spherules.


"Joe Knapp" wrote in message
y.com...
"Timothy Demko" wrote
Close-ups like this:




http://marsrovers.jpl.nasa.gov/galle...2P2933M2M1.JPG

continue remind me of textures and fabrics I've seen in travertine
and
sinter deposits.

Would sinter deposits be associated with hot springs such as in theis
New
Zealand shot?