On the Road Again - volume 5 - Page 3

Previous 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 ... 29 Next
Author Message
Ben


Posts: 2270

Reply: 41



PostPosted: February 9, 2010 3:31 PM 

James; At the time Meridiani became an arid desert,the water table was lowered and IMO shortly thereafter the climate became very cold so that the water below the surface froze creating permafrost and has probably stayed this way since.

THis prevented any glacial activity or freeze-thaw of surface water.

I don't have a handle on the timing of the suggested catastrophic releases of water to the surface and I am still uncertain what caused them.

Barsoomer; These rocks consist of alternating layers of hard and soft material.

When the view shows a planar layer of hard material,it is less weathered compared to one composed of softer material.

Can't tell if Porcupine is a COOB. Wink


Winston: Yes the normal winds allow the accumulation of thin dust layers.

But; the very lack of a thick dust layer to compensate for the amount of material worn off the Meridiani beds,can only be explained by its having been transported elsewhere where thick dust deposits are visible.

I don't see how you can prove (by remote methods) how the berrys and stems were formed.

Do you have any suggestions ?

Kye Goodwin


Posts: 1166

Reply: 42



PostPosted: February 9, 2010 3:33 PM 

I just got interested in the possibility that suspended frost particles could "scour" rock at Meridiani. I've come up with a Mohs hardness for magnesium sulphate (a major rock component) of 3.5 and for ice at -70C (a typical nighttime temperature at Meridiani) a Mohs hardness of 7. So far so good, but I also know that even at very low temperatures a layer of liquid water a few molecules thick forms wherever ice meets other minerals. I think that there are possibilities in this notion but I can't take it any further.

bewleys


Posts: xxx

Reply: 43



PostPosted: February 9, 2010 3:52 PM 

Millions of years of weathering and erosion ?

Barsoomer


Posts: 344

Reply: 44



PostPosted: February 9, 2010 4:41 PM 

A couple of additional points:

1. Some of the berry stems in Horton's 3D of Porcupine are curved. For example, see the stem closest to the bottom left in the colored frame. (This is on the main rock, not on Porcupine itself.) It is difficult to understand how wind-based erosion would create a curved stem.

2. In general, the vertical faces of rocks seems to have less of the "filling" than the horizontal faces and this seems to be independent of the direction of the face. Porcupine is an exception to this, but it may be a fragment that has fallen off a vertical face.

3. Is it possible the dust-laden wind may have a filling effect rather than an eroding effect? Thus, the rock surfaces that appear most eroded may in fact be less filled instead? I acknowledge this is highly speculative and might be easily refuted, but it is interesting to consider.

James


Posts: 3

Reply: 45



PostPosted: February 9, 2010 6:17 PM 

Ben, reply 41,
Okay. But is still seems likely that where there was much water, there was also ice. Apparently many agree with this view. Here is another reference: from Niles, P.B.; Michalski, J. AGU Fall
Meeting 2008; 'Origin of the Terra Meridiani Sediments...' "The climate, sedimentology and geology of the Meridiani sedimentary deposits are best explained by the eolian reworking of the subliminated residue of a large scale ice/dust deposit."
(abstract available on-line).

LWS


Posts: 3062

Reply: 46



PostPosted: February 9, 2010 6:41 PM 

Hi Ben, Bill, et al;

Another view of the degraded "rock" that I made a few mistakes on yesterday. This time from another angle.

It looks like a slumped completely degraded and chemically altered rock. How could wind erosion do this? Could it have burst off the main rock (chocholate hills) as a partially degraded piece of rock and then reacted with something at the soil surface to become what it now is?

Winston

Bill Harris


Posts: 72

Reply: 47



PostPosted: February 9, 2010 10:11 PM 

That "latest" view of Chocolate Hills (taken a couple of days ago) shows an interesting side of that rock. I'm not sure of this is a "softer" bed of that rock or a "softer" rock that happened to lay on it. "Softer" meaning more readily weathered. I'm looking forward to getting more Pancams and MI's from this site-- so many tasty tidbits.

And notice how the ejecta blanket is behaving under the ROver's wheels-- this material is clearly fresh and weathering. Happily, it has enough rock fragments mixed in to be a decent roadbed material, so we'll be able to (cautiously) move arounf the crater.

--Bill

LWS


Posts: 3062

Reply: 48



PostPosted: February 9, 2010 10:21 PM 

Ben; Re your #41. You said "I don't see how you can prove (by remote methods) how the berrys and stems were formed."

It was largely by remote control methods that the current hypothesis on their formation was developed and formulated and are now largely accepted. Yes, one can't prove that the hypothesis is true but one can point out some of the flaws in that hypothesis and suggest another one if it is warranted. Of course any resultant hypothesis would also not be proven until properly equipped rovers go back there.

Re. casting doubts on the current hypothesis there are several things that can be done, e.g.

1. Take every opportunity to study the berries carefully, not just accept that they are generally analogues of Earth's haematite concretions and look nowhere else.

1a. Look carefully at the curved berry stems and the tubular things on the surfaces of some rocks at concepcion.

2. Do simulation experiments under, as far as possible, minutely detailed martian environmental, physical and soil chemical conditions to determine if it is possible that berries can form under conditions as close as possible to those determined to be extant under current martian conditions.

3. Look carefully at the whole question of what kind of haematite pervades the surface at meridiani. Is it really the grey haematite they were expecting to find or could it be something else that a number of papers hint at?

4. Redo the berry bowl study (perhaps at concepcion) to see if the results corroborate and bear out those of the original experiment. There are papers which suggest that there is only a thin film of haematite over the berries and that this film covers the whole surface. If that is true the gospel that berries are totally made up of hematite could redo the whole concept of berries at meridiani.

5. Do statistical imageJ studies to compute how long berries should last on the surface of mars under current conditions, factoring in such variables as realistic data on split and otherwise degraded berries, brownish berries that probably have little haematite content, range of dust particle sizes on the surface, amount of dust likely to be airborne aunder normal conditions and dust storm conditions, frequency of dust storms, etc.

6. have a second look at identifying the probability of liquid water, however sparse, existing on the surface at meridiani

7. Do time lapse studies over several months on disturbed trenches rembering that at Purgatory it only took a few weeks for significant changes in trench walls to have been imaged. Also at Victoria significant changes were also seen, not only in crossed tracks but in token studies on the dark streaks.

8. etc., etc.

Winston

serpens


Posts: 169

Reply: 49



PostPosted: February 9, 2010 10:25 PM 

Chocolate Hills is made up of 2 ejecta blocks and as Bill says, there does seem to be anisotropic (direction or orientation dependent) weathering. In fact this seems to be the key to Chocolate Hills and some interesting data points arise if we permit the orientation of the blocks to influence our view of the weathering process, using the layering as the common baseline.

Looking at LWS’s image in 46 above (although I am an enthusiastic fan of Hortonheardawho’s x-eye images), the layering on the left hand block shows that the smooth side with the fracture fill adhering was in fact buried and is most probably the side of a desiccation crack that had some chemical induration. (Point goes to Ben). So we now have a key data point. Any weathering of that side of the block must have occurred after the impact. The remaining fracture fill tells us nothing as the disruption to this would be a result of impact trauma.

I really think that the side of the left hand block represents the plane of separation of the ejecta along a layer, uring the impact. So we can see an exposed layer from around half a meter depth. The fragmented appearance is possibly the result of the separation trauma and instantaneous sandblasting as underlying strata fragmented. Trying to differentiate between this and any subsequent weathering will be a real and possibly insurmountable challenge.

It seems reasonably certain that the other block shows the old surface before impact. So we cannot draw any conclusions based on this aspect of the block as this is cumulative weathering over an extended period before impact. It tells us nothing about post impact effects. The layered sides that would have been buried seem to show excessive weathering, particularly of the softer layers. Did this occur in the time following the impact, or is it the result of shock induced spalling along the weakest axis? MI of this area may give an indication. But the bottom of the triangular exposed side seems less worn. Is it possible that this was protected by dust post impact, which subsequently, and slowly, blew away? This is possibly another quite significant erosion data point.

So what weathering post impact can we posit? The fracture fill side of the left hand block does not seem to have weathered very much at all. Possibly this could confirm erosion resistance due to hardening by a chemical induration process. The berries on stalks seem to concentrate on the layered sides, which indicates that they were exposed by physical erosion. Why physical? Because if chemical erosion were responsible then the tails would have eroded the same way as the surrounding rock. The tails could only form if the non eroded rock was protected, which indicates a directional mechanism. Curved stems would substantiate this directional erosion as the berry itself would affect the local pressure variations as the tail formed. So how long would it take to erode say 3-4 mm of this kieserite cemented rock? I don’t have a clue – but I think it would be a lot longer than a thousand years in this current environment.

The periodic cleaning events on Opportunity seem to indicate that there is currently a balance between dust deposition and erosion. While it is tempting to believe that water could result from the (very occasional and very thin) frosts seen at Meridiani this is difficult to correlate to a kieserite cement. Kieserite readily converts to hexahydrite and epsomite when exposed to water. But this is not a reversible process so kieserite cannot be preserved in a deposit that has experienced any hydration after it formed.

Apologies for such a lengthy post and this is just personal opinion. But I hope it gives basis for further discussion on this fascinating thread.

LWS


Posts: 3062

Reply: 50



PostPosted: February 9, 2010 10:33 PM 

Bill; Re your 47. I was looking at the Hazcam showing the wheel tracks and it looks as if Oppy was deliberately trying to dig into the soil. The soil was indeed looking soft. I wonder if sometime in the distant future when they get proper instruments on Mars, that they will look back at comments made re. absolute dryness on Mars and the authoritative statements that the areas that look like mud and recently flowing water are just fine dust that flows and acts like a liquid, and laugh Ha! Ha! Ha!

I really appreciate your comments on this blog. They add to the current very observant posts on the minutiae of Oppy's images by Hort, Barsoomer and Kye that explore areas that most seem unwilling to venture into.

Winston

LWS


Posts: 3062

Reply: 51



PostPosted: February 9, 2010 10:43 PM 

Serpens; Re your #49. A very informative speculative post. Many points to ponder.

Winston

Ben


Posts: 2270

Reply: 52



PostPosted: February 9, 2010 11:01 PM 

Winston; I can't guess where your reply #46 rock came from but yes it is being "disggregated" which implies no specific method of degradation; but would include Serpen's (impact forces).

Great list Winston. I hope responsible persons will read and take note.

Ben


Posts: 2270

Reply: 53



PostPosted: February 9, 2010 11:25 PM 

James; I would like to read that AGU paper but can't find it listed in that meeting program. Any help please

Bill Harris


Posts: 72

Reply: 54



PostPosted: February 10, 2010 8:47 AM 

They've got the Microscopic Imager looking at the "fracture fill".

http://qt.exploratorium.edu/mars/opportunity/micro_imager/2010-02-10/

--Bill

Bill Harris


Posts: 72

Reply: 55



PostPosted: February 10, 2010 10:04 AM 

Interesting first MI-look at the "facture fill". To paraphrase Dave Bowman in 2001, "My god, it's full of berries". It looks like the MIs were to postion the APX on the "fracture fill", so it'll be sniffing for a few days. And a new L257 Pancam of one fracture face of Chocolate Hills.

I'm going to go do some popcorn and wait for the Horticolors to come out...

--Bill

James


Posts: 3

Reply: 56



PostPosted: February 10, 2010 10:44 AM 

Ben,
Here's some info I have: The paper was Presentation P43B-1396 at the AGU Fall Meeting 2008. Lead author is Paul Niles of NASA Johnson Space Center. The paper's opening paragraphs are available at [link] The entire paper can be downloaded from there too, but you must register.
Your interest is appreciated.

Bill Harris


Posts: 72

Reply: 57



PostPosted: February 10, 2010 11:43 AM 

Going back to Hort's Post #15, and Ben's #20 here is another example of classic exfoliation. Temperature changes-- and possibly freezing and expansion of trapped water-- cause thin layers to flake off of the rock parallel to the bedding planes.

--Bill

Barsoomer


Posts: 344

Reply: 58



PostPosted: February 10, 2010 11:47 AM 

The coating on Chocolate Hills may look like fracture fill to a geologist, but to a layperson, it looks like the rock simply got splattered with mud during the impact process.

LWS


Posts: 3062

Reply: 59



PostPosted: February 10, 2010 1:14 PM 

Hi Bill

It may look like classical exfoliation to you, and mud splattered on the rock to barsoomer but to me it looks like a stage in a biological dissemination process.

Look at the Original size image in my #32 in this thread (its a bit clearer). Ignoring the current hypothesis on the diagenesis of the berries, what the image says to me is that the "fill" is weathering / eroding by some means and showing clearly a number of stages in the development of the berries. (I'll post some MI crops later).

Look at the berries on the rough appearing matrix. They are not placed in the customary arrangement of berries that we are accustomed to seeing. They are ordered, fairly packed of very constant size, etc. Now look at the berries higher up on the rock, still attached to the rock surface they show very long curved "filaments / tubes" from which single berries seem to be emerging or eroding.

Today's MI's also show a number of stages in the development of the berries. These would generally be interpreted as stages in the breakdown of the berries but I like to think of them as going the other way. They are a range of sizes and one can see clearly how material from the underlying matrix becomes aggregated into the small berry spheres in one area. And then there are the mature berries in another area whose surfaces look somewhat metallic as they glint in the reflected light.

Several similar berries were imaged near Erebus. Much of this has also been seen in other earlier images but never, as far as I recall, in just one area.

This is a veritable cornucopia of berry delights.

Winston

hortonheardawho


Posts: 3465

Reply: 60



PostPosted: February 10, 2010 1:44 PM 

sol 2150 ( Feb 10, 2010 ) colorozed MI panorama of Chocolate Hills:

with a location link.

This is my "first hack" at this panorama and may squeeze a bit more out of the JPGs. I will create some HI-LO ( highlight-shadows) versions and 3D pairs later today.

Unfortunately, the most interesting parts are in the shadows and mostly disappear in the JPGification of the image - but it seems that there are numerous berries under the rock coating and some interesting "strand-like" features that may well not be "real".

Perhaps the MIs will be re-done so that the interesting bits are not in shadow.

Naah, the "big boys" can see what they want to see just fine. I'll have a peek next year - if there is any interest at that time.

Previous 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 ... 29 Next


Join the conversation:















Very Happy Smile Sad Surprised
Shocked Confused Cool Laughing
Mad Razz Embarassed Crying or Very Sad
Evil or Very Mad Twisted Evil Rolling Eyes Wink
Powered by MTSmileys