Mars - Concretions or Secretions?

March 12, 2004

Please feel free to publish your future Mars geology or biology
retractions here.

http://qt.exploratorium.edu/mars/opp...MP2937M2M1.JPG

Thomas Lee Elifritz
http://elifritz.members.atlantic.net

Thomas Lee Elifritz wrote:

March 12, 2004

Please feel free to publish your future Mars geology or biology
retractions here.



Okay, I haven't even made up any crackpot theories yet. But I'll
retract them
right now. ;-)

"Thomas Lee Elifritz" wrote in message
om...
March 12, 2004

Please feel free to publish your future Mars geology or biology
retractions here.


Have you seen the pic of the interior of the Spirit crater?
Spectacular! If you look at the walls of the crater along
the right side of the pic, you'll see they're covered by
rocks evenly as one would expect. But the left opposing
and ...darker..crater wall is entirely different. Hardly a rock
to be seen on the wall or below on the crater floor.

And the dark opposing wall is also clearly rippled. It must
be a sheet of cemented dunes made of spheres.

So the rock face above the rippled wall is certainly much
like the crusted Opportunity outcrop. Likely much
older and more weathered though.

But a large reef still!

It's also becoming clear that the dark/lite rocks show
that this was a sea that emptied quickly, like a dam
burst. The rocks were fully coated by the ripples, then
washed half off by the fast flowing water.


This crater will be just a tease though, compared to the
large Opportunity crater. What a great adventure this is.


Jonathan

s






http://qt.exploratorium.edu/mars/opp...MP2937M2M1.JPG

Thomas Lee Elifritz
http://elifritz.members.atlantic.net

In article ,
says...

snip

Have you seen the pic of the interior of the Spirit crater?
Spectacular! If you look at the walls of the crater along
the right side of the pic, you'll see they're covered by
rocks evenly as one would expect. But the left opposing
and ...darker..crater wall is entirely different. Hardly a rock
to be seen on the wall or below on the crater floor.

And the dark opposing wall is also clearly rippled. It must
be a sheet of cemented dunes made of spheres.

Nothing like the Meridiani spherules has been found in Gusev. Basaltic
pebbles, yes. Spherules, no. I'd be a LOT more willing to bet that the
dune ripples in Bonneville Crater are just that -- sand dune ripples.
Made of the dust that has accumulated in the crater over the millennia,
dropped there by wind and sandstorm. Not likely made of spherules at
all. I'd wait until something resembling the Meridiani spherules are
actually observed in Gusev before making THAT assumption.

So the rock face above the rippled wall is certainly much
like the crusted Opportunity outcrop. Likely much
older and more weathered though.

Again, I doubt it. I don't see anything like the slabby, layered
characteristics of the Meridiani outcrop in the Bonneville Crater
images. Just a regular rock population, no particular layering evident
in the rocks themselves. And the rocks are almost definitely of the
same type and composition as the rocks on the rim, that Spirit will be
examining over the next week or so. Those look exactly like the other
basaltic rocks that Spirit has been looking at all over the Gusev site,
so while it's a disappointment to those looking for lacustrine materials
in Gusev, it begins to appear that the rock layers exhumed at Bonneville
are all volcanic basalts.

Of course, we'll know better when they get a full set of mini-TES
observations of the crater interior, RAT some of the rocks on the rim,
and take APXS and Mossbauer readings of the rocks and soils on the rim.
We'll have some results from those activities in a week or so, probably.
I'm really looking forward to seeing if there's any compositional
differences between the rocks at the rim and those out on the plains,
because the rim rocks ought to have been blasted from the deepest level
of the crater, and thus represent the rocks lying that far below the
surface of the rest of the plains.

But a large reef still!

Unlikely, just as your reef explanation for the Meridiani outcrop is
extremely unlikely. I'm not ruling it out, but I still think it's
unlikely.

snip

What a great adventure this is.

With that sentiment, I completely agree! What a great time to be alive.

Doug

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

snip

Have you seen the pic of the interior of the Spirit crater?
Spectacular! If you look at the walls of the crater along
the right side of the pic, you'll see they're covered by
rocks evenly as one would expect. But the left opposing
and ...darker..crater wall is entirely different. Hardly a rock
to be seen on the wall or below on the crater floor.

And the dark opposing wall is also clearly rippled. It must
be a sheet of cemented dunes made of spheres.

Nothing like the Meridiani spherules has been found in Gusev. Basaltic
pebbles, yes. Spherules, no.



Not yet. I bet you money that on the floor of the Spirit crater spheres
will be found.



I'd be a LOT more willing to bet that the
dune ripples in Bonneville Crater are just that -- sand dune ripples.
Made of the dust that has accumulated in the crater over the millennia,
dropped there by wind and sandstorm. Not likely made of spherules at
all. I'd wait until something resembling the Meridiani spherules are
actually observed in Gusev before making THAT assumption.



If the Opportunity site suffered a large flood, the soil, spheres
and all would be washed away. And only the underlying
rocks and cemented buried dunes would be left. That
is what we are seeing at the Spirit site.

But the life that existed at both sites are the same. There
will be spheres found at the Spirit site. The photos make
clear the Spirit crater dunes are water features. The loose
sand and soil long ago was washed away.

Jonathan

s




So the rock face above the rippled wall is certainly much
like the crusted Opportunity outcrop. Likely much
older and more weathered though.

Again, I doubt it. I don't see anything like the slabby, layered
characteristics of the Meridiani outcrop in the Bonneville Crater
images. Just a regular rock population, no particular layering evident
in the rocks themselves. And the rocks are almost definitely of the
same type and composition as the rocks on the rim, that Spirit will be
examining over the next week or so. Those look exactly like the other
basaltic rocks that Spirit has been looking at all over the Gusev site,
so while it's a disappointment to those looking for lacustrine materials
in Gusev, it begins to appear that the rock layers exhumed at Bonneville
are all volcanic basalts.

Of course, we'll know better when they get a full set of mini-TES
observations of the crater interior, RAT some of the rocks on the rim,
and take APXS and Mossbauer readings of the rocks and soils on the rim.
We'll have some results from those activities in a week or so, probably.
I'm really looking forward to seeing if there's any compositional
differences between the rocks at the rim and those out on the plains,
because the rim rocks ought to have been blasted from the deepest level
of the crater, and thus represent the rocks lying that far below the
surface of the rest of the plains.

But a large reef still!

Unlikely, just as your reef explanation for the Meridiani outcrop is
extremely unlikely. I'm not ruling it out, but I still think it's
unlikely.

snip

What a great adventure this is.

With that sentiment, I completely agree! What a great time to be alive.

Doug

"jonathan" skrev i en meddelelse
...

snip speculation

The photos make
clear the Spirit crater dunes are water features. The loose
sand and soil long ago was washed away.

We may argue about the origin of the spheres, but you owe us a through
explanation for the above statement.

http://www.msss.com/mars_images/moc/themes/DUNES.html

Carsten

"Carsten Troelsgaard" wrote in message
. ..

"jonathan" skrev i en meddelelse
...

snip speculation

The photos make
clear the Spirit crater dunes are water features. The loose
sand and soil long ago was washed away.

We may argue about the origin of the spheres, but you owe us a through
explanation for the above statement.

Don't hold your breath waiting for an explanation.
Especially a physical one.
You can't squeeze blood from a stone.
He can't give what he hasn't got.


http://www.msss.com/mars_images/moc/themes/DUNES.html

Carsten

"Chosp" skrev i en meddelelse
news:C8B5c.84889$h23.52982@fed1read06...

Don't hold your breath waiting for an explanation.
Especially a physical one.
You can't squeeze blood from a stone.
He can't give what he hasn't got.

Well, as a mathematician he may give us a lesson in biology - let's see if
he up to give us one in geology.

Carsten

"Carsten Troelsgaard" wrote in message
. ..

"Chosp" skrev i en meddelelse
news:C8B5c.84889$h23.52982@fed1read06...

Don't hold your breath waiting for an explanation.
Especially a physical one.
You can't squeeze blood from a stone.
He can't give what he hasn't got.

Well, as a mathematician he may give us a lesson in biology - let's see if
he up to give us one in geology.

Except that he is not a mathematician.
He doesn't even pretend to be one very well.

"Carsten Troelsgaard" wrote in message
. ..

"jonathan" skrev i en meddelelse
...

snip speculation

The photos make
clear the Spirit crater dunes are water features. The loose
sand and soil long ago was washed away.

We may argue about the origin of the spheres, but you owe us a through
explanation for the above statement.


Do you really think this pic shows wind blown dunes? Then why
does the dune define a line precisely where water would
stand were it filled? Why is the dune darker on the wall
then on the floor? There is clearly a difference between the
dune on the wall and on the floor, if wind and dust were
the cause of both then there shouldn't be such a well defined
line separating the two. Your wind is very selective.
And your dust clings very well to the side of a steep
crater wall.
http://marsrovers.jpl.nasa.gov/galle...0P2285R7M1.JPG


And in this picture there's a rather flat dune, are you saying the
wind blew the rocks away? Where did they go? They clearly
sank in the mudflat, which means that dune formed when
water was still there. And it's stayed there since. Wind blown
dunes are transient features that come and go.
http://marsrovers.jpl.nasa.gov/galle...0P1943R0M1.JPG



And in this pic the rock appears to be lying on top, why didn't the
wind blown dust form around the rock, or fill in underneath it?
Shouldn't the dust be lying up against the rock?
http://marsrovers.jpl.nasa.gov/galle...P2515R1M1.HTML

And it's clear the dark portions of the rock are continuous with
the dunes. Is this rock half covered with dark dust, or half
covered with lite dust? And explain how dust can define such
a fine line.
http://marsrovers.jpl.nasa.gov/galle...1P2433R1M1.JPG



The dark and lite dust seems rather selective
http://marsrovers.jpl.nasa.gov/galle...P2313L6M1.HTML
http://marsrovers.jpl.nasa.gov/galle...0P2530R1M1.JPG



There's no way wind did this, the segregation of the rocks by size
can only be done by water. Have you ever been to a beach?
http://marsrovers.jpl.nasa.gov/galle...9P2213L6M1.JPG





http://www.msss.com/mars_images/moc/themes/DUNES.html

Carsten