Mars Spirit finds rounded Boulders (pic)

Now THESE are interesting..



I'm not sure of the size yet..nothing has been published.
They remind me of old exposed granitic type rocks. But who knows?

They could be old water worn rocks..But then again, Granites, and other rocks can wear away like the layers of an onion (see Half-Dome, Yosemite)..

How about some theories? Any Geologist out there?


Oh, and here are links to the origninals



Boulders, Spirit, Sol 439

The colors are intriguing.

The colors are altered

Well, They aren't quite natural..
I should have stated that these were false color.
I only had 3 images to work with..
Two of which were out of the usual visual spectrum..But I assigned them normal RGB designations..
It makes the differences of color, or, chemical makeup really stand out..


[edit on 30-3-2005 by spacedoubt]

Water could of rounded them...hands could of rounded htem...who knows!? Wish I did! Good find

I agree with ladyV it looks like water was the one to give them their round look.

Look like rocks you may find here in earth.

Oh, that's Colosass's big toe.

Now really, it does appear that Mars must of had water flowing in rivers to smooth a rock like that.

.
It appears more and more likely that Mars was once a very different planet, with flowing water.

Having said that, I think it is possible that these rocks were weathered by wind (however weak) and dust over a long period of time—sandblasted in effect, like some of the formations of the desert southwest on Earth.

We could be talking about vast years here. Without rain, or the actions of vegetation or animals, the surface of Mars may remain virtually unchanged for extremely long periods of time. Nothing but gently swirling dust eon after eon….
.

Erosian isnt just from water. It can be from wind, sand, two rocks rubbing against each other.

Originally posted by Croat56
Erosian isnt just from water. It can be from wind, sand, two rocks rubbing against each other.

yeah, my guess would be thousands of years of being sand blasted.

Wind, sandblasting, water..
All could be contributing factors..
Here is another shot of the area..
More Boulders


However,

If you take a look at other rocks in the area..Especially the more angular ones, you may notice a pattern. They tend to have "direction" to their erosion..
Like they have been sitting in the same place, for thousands, or millions of years, with a wear pattern that points to prevailing winds..One face is worn much more than the others.

The rounded ones seem to be eroded a different way. From all directions.
This type of erosion CAN happen in a matter of hours actually. There are deposits of this type (shape) of rock, where I live..It was caused near the end of the last ice age, an Ice Dam upriver from my location gave-way, and a HUGE slurry of mud, rocks, sand etc..came thundering down the valley. Where the river spread out, the water slowed, and deposited these rocks..( I collect them for landscaping purposes). So this could have been a quick, one time event..
There is still a possibility though, that these were formed over a longer time period..

The rounded ones seem to be eroded a different way. From all directions.
This type of erosion CAN happen in a matter of hours actually

This is incorrect. This type of erosion cannot happen in hours, the rocks which you collect have simply been weathered and eroded over millions of years and then redeposited when this flash flood occured.

The rocks on Mars as most people have picked up can be formed either via water, or via wind. It would be very difficult to tell which unless you could have a closer look at the rocks, and even then it is difficult. However the rocks are very pock marked, and look volcanic to me. As as geologist I would expect the rocks to be a lot smoother if they had been eroded down by water, but this isn't always the case.


[edit on 1-4-2005 by Rock Hunter]

Rock hunter,

I think the term is "jokulhlaup"..A rapid super erosional flood.

The story of these river rocks was told to me by a Geology Professor from
the University of Nevada. I had a hard time believing it as well.
But then, my Rock tumbler does NOT take a million years to polish rocks.
And the conditions are similar..A gritty slurry, combined with tumbling rocks.

Where do you rock hunt, by the way?

The rocks look like earth rocks, both ones rounded by water and ones not rounded by water. IE they are 'uninformative' wrt the pressence of water.

But they ARE informative..
Pay attention to their context.

They look out of place. Which is a clue, that is ALWAYS a clue.
Compare them to the surrounding rocks..Coloring, texture, shape.
Now, theorize..It's fun...and usually not painful..

Terapin,

Thanks for the great response.

I certainly agree that the rounded ones could be wind sculpted..
But, for some reason, they really stood out when I first saw the pic..
They are somewhat different.

Here is a pic that shows the most common style of wind erosion in the area..
It is from a current SOL, from Spirit

Wind faces

The rocks are lined up, almost like a stadium full of people looking in the same direction, with erosion, mostly on one side.

It just makes me think the the rounded ones were transported to the area. Maybe by a flood..Maybe not..

On the OTHER hand..if you look closely at some of the rounded ones..There appears to be a scattering of little nuggets lying around each one..Which points to exfoliation, like old granite, as it decomposes.