Burns cliff

I'm going to go out on a limb and wait for someone to saw it off -- and for elephants that is a sight to see:

What I'm hinting at is ripple marks.

I think everyhing NASA has said so far about this crater is wrong.

I think it was created before the major water event.

I think all the evapotite beds are horizontal -- not vertical.

And I have always thought Burns "cliff" would be the key, because I think the top of the "cliff" was a high and dry area and bottom parts a basaltic beach front awash with whatever was happening in the bowl of the crater.

I think seasonal wind blown ripples deposited the freshly created berries in the freshly deposited edges of evaporite as the lake dried up.

I predicted a million seconds ago that the salt content would go up the further down in the crater we went because of the increasing concentration of remaining salts in the water. I think that has been confirmed.

I pointed out even earlier that the erosion of the beds was entirely consistant with thin horizontal layers draped over the topography of the crater

I made a suggestion even further back that the berries themselves were similar to ocean manganese nudules and even guessed at the length of time the lake existed based on the size distribution of the berries and the growth rate of Earthly nodules.

( Say, did I hear the sound of a branch cracking?)

OK guys, start sawing...

Soory, I meant BERNOULI force, same thing that makes a carburetor generate vaccum.

Wow, horton, got a parachute?, its a long way to the ground.

The evaporates drape over the edge, and they appear to be like thin plates, even high up on the edge. With sand, or other, under them. Not meters thick, like i thought they had said earlier.

You say the berries, were formed and then encased in the evaporates. Not like Nasa says, created in, the evaporates. That makes sense, for many reasons. Whats yours?

Don't maganese nodules have growth rings? I know these are not maganese nodules, but are there hematite nodules found on our ocean floor?

Here is a very interesting reference to the growth rate of manganese nodules. Be patient -- it takes a while to load.

An average nodule has 18% Mn -- and 13% Fe -- as oxyhydrides!

It seems like a plausible mechanism to form the spherules on Mars.

Whugga, whugga, whugga.... how long can you tread water?

The dunes are just that, dunes. Ripples need moving water and you aren't going to have that in the bottom of a 400' pond. There is no evidence of water in the crater, and nothing I've seen looks like a beach or terrace.

The wind blows across the plain,picks up fine material and transports it as "bedload", by saltation or in suspension. As it flows over the crater, velocity drops and so does so does the "sediment" load, which is deposited in the crater. There are some not-defined aerodynamics going on to sculpt the fines into n-th order dunes.

Aeolian erosion is clearly a force here. An aerial view of craters in the area show light-colored downwind tail to the SE, this material is likely abraded from the evaporite unit that forms the crater rims. I expected to see aeolian erosion on the face of Burns Cliff since it is facing the prevailing wind and the windborn material would tend to sandblast that exposed area.

The blueberries were formed in the evaporite beds as secondary features. As the evaporites are eroded by the wind, the modules are left behind and currently form a desert pavement which minimizes erosion.

One puzzler for me is the "landslide" areas visible on the slopes of Endurance-- the area around Wopmay is an example. My initial take was thay they are simply slump features where gravity is trying to get everything down to base level, but there is something "wrong" with that. I dunno what that is...

--Bill

These nodules grow around a nucleus of sharks tooth, or simular, and are very layered. they grow in the very upper layers of the sediment bed, and are kept, in theory, on top of this bed, by bioturbitation. That is things such as crabs, and holothurians.
(i wonder what keeps all the mars berries on top of the soil?)
The slow moving currents, bring the minerials for growth.

These mag nodules are not anywhere near as round as mars berries.

So, shape? Growth rings? core?

I learned a new word, bioturbidation.

Maybe, the core of the mars berries are Round, to start with?

I believe the area of mosaic-like slabs, seeming to drape over the topography of the crater, is an illusion. They are probably a jumble of blocks, disrupted by the Endurance impact, that have been scoured down and streamlined by ceaseless wind erosion. The laminations seem to go in random orientations in each exposed stone, as would be expected in a chaotic pile.

The "landslide" areas stated by Bill Harris puzzle me too. They appear to be weathering out of the slope, where they form promontories, rather than sliding from above. They remind me of igneous intrusions weathering out of a hill or mountainside, though they likely aren't. The rock itself appears to be an indurated version of the laminated rock that is prevalent everywhere. I think they are either a bed of particularly large concretions or are areas of rock shocked by the Endurance impact (the same material that forms pedestal craters elsewhere?).

Horton, re reply 34:

Remind me why you think there is basalt at the top.

With respect to the beds seem defined by the density of the concretions I agree there is a relationship. However, as the concretions are clearly later than the bedding it is something in the bedding that is controlling the density of concretions, not the other way round.

Cheers

Jon
What intrigues me is the fact that the beds seem defined by the density of blueberries. IE, the factors that controlled the blueberry formation controlled the bedding.

Bill, re reply 38:

there has been a lot of studies of the behaviour of sediments under marian conditions, including both mathematical models and wind tunnel studies. These have then been cross checked against the known properties of martian dunes.

As far as I recall the results that sediments are entrained at velocities an order of magnitude higher on mars than on earth because of the lower density. However, once entrained, the saltation height is much greater, because of the lower gravity. As a result Martian dunes are much higher in relation to their wavelength than terrestrial ones. To the best of my knowledge the sand-silt distinction hold true on Mars, as on earth.

Cheers

Jon

Interesting stuff going on (flowing?) underground as a bit below Burn's Cliff there is another seeping rock slab:

Photo rotated 25 deg CCW

Horton

I confess I am having a real trouble understanding your point(s) in reply 41. You seem to be saying that the crater predates the evaporitic sediments, that the evaporites formed in the crater, which was formed a lake.

This does not make sense of the data.

First, the "ripples" have the morphology and scale of sand dunes formed by wind. They don't form this size in lakes.

Second, the same evaporitic sediments are found in the walls of Fram, Eagle, and Endurance craters. As far as we can tell from MER images, they also occur in the walls of other craters as well, and are exposed in the etched terrain. The eavporite sediments are older than the craters. As we have seen in both Endurance and Eagle (Fram is probably too degraded) the fact that sediments dip away from the crater in all the walls, the dip rapidly approach horizontal with distance away from the crater, and the radial faults and fractures all point to this. It is logically impossible for a crater to be older than the material in which it forms. It is like saying a bullet hole is older than the glass it has passed through.

Third, who has said the evaporite beds are vertical? Sediments are laid down horizontally. The evaporitic sediments at Meridiani are still horizontal, apart from some local dip caused by impact craters.

Fourth, while increasing evporite content down the crater walls is consitwent with a salt pattern formed by a lake in the crater, it is also consistent with a range of other causes, including a change in composition in the host succession.

Fifth, there is no evidence of drape that I can see. I do see lots of fractured blocks that have been beveled to the same level. I also see surface crusts of cemented material. But this does not mean that the evaporite sediments have been draped over the crater. Quite the contrary, it is eactly what you would expect from weathering and erosion of a crater in such seidments in a hyper arid environment.

Sixth, manganese nodules? They contain manganese for a start, these concrtions don't. Then they form in areas of essentially zero sedimentation, whereas Meridiani was a site of active sedimentation. Als they form only on the surface-water interface, the Meridiani concretions have formed at depth after deposition. This does not mean to say they are without value as analogues, they do after all provide yet another example of spheroidal concretions. But that is about as far as it goes.

Cheers

Jon

Jon, thanks for your taking the time to reply to my "out on a limb" view of Mars.

A few additional comments, in reverse order.

6)The nodules were presented as an alternative model to the concretion model.

You will notice I joked about the branch cracking. Of course I'm not claiming the spherules are manganese nodules -- I'm simply pointing out another route to creating a zillion almost uniform spherules over a very, very large area.

The conditions you cited for manganese nodules are precisely the ones I thought applicable to Merdianni: A shallow sea with no suspended particles -- just a giant beaker of mostly chemistry!

I don't see any sedimentation at all there -- I see evaporation and precipitation out of solution.

Er, how deep and how long was the Eagle formation when the spherules concreted?

Doesn't their uniformity bother your geological nose?

I have several examples of Earthly hematite spherules sitting on my desk -- along with Ordovician sandstone spherules ( Thanks Robert ) -- and not one displays the uniformity of the Martian spherules!

I think the spherule question will not be settled until a sample return mission -- I, for one, most likely will not be here to appreciate the results.

5) Evidence of Drape:

Warning: 3.1 MB links.

This is what got me starting to think about the time order of events. The layers on the two eroded rocks follow the contour of the crater.

I would suggest a good stereo viewer like StereoPhoto Maker to view the details on the lip of the crater.

I will break here and start another post.

4)The increasing concentration of salt was a prediction I made based on the Endurance lake idea. In my dreamtime I see Endurance as a "deep" spot in a very shallow Meridiani Sea that was the last gasp of the wet epoch.

Specifically, what other causes do you suggest, and what are your predictions about what will be found at Burns Cliff?

3) Perhaps I didn't make myself clear by describing the beds as horizontal.

What I was talking about was the numerous lower bands on Burns Cliff which I argue are not the edges of successive layers -- but rather the top of one bed with successive changes in conditions in the waters of Endurance lake -- once it was isolated from the rest of the dying sea.

I postulate the "cap" of dark basalt on Burns Cliff was above the lake as it dried out and that the bands are "ripple marks" on a very short and steep beach that were deposited as the waters evaporated.

2) I'm glad you mentioned Fram crater! Now that's what I would expect to see in a crater created after the water epoch.

The material lining Endurance was created at the same time as the material in Eagle and Fram.

We have seen only surface material that participated out of solution of a common shallow sea.

1) Perhaps "ripple" is the wrong word to use for the banding on the lower portion of Burns Cliff.

I was trying to imagine a seasonal wind driven process to concentrate the spherules rolling against a steep beach, because once isolated, I couldn't think of a way to change the chemistry in the lake in a long periodic way.

But perhaps there were wet episodes after the lakes isolation that brought fresh water to the crater that changed the rates of deposition.

I think that the tale of Endurance is the ending chapter of story of surface water on Mars.

Thinking up alternative histories beats late night television -- and it's a way of testing the "accepted" dogma.

Say, is there an accepted theory yet?

Crack!

Warning: 2.2 MB links.

L2/L5/L7:

R1/R2:

That sound you heard was branch 3 of my argument giving way:

The fine beds here are not just painted on. They have depth. Also, they seem to be tilted in just the way you would expect for a rebounding crater wall...

Maybe that crack was branch 1 giving way too...

Hey, how about that "floating" berry in the center of the images! I wonder how much force it would take to break it loose...

Talking about being out on a limb

These grey fines, hematite? Same spectra as the berries.
Although it seems in places to be flowing down hill, it also seems to be eminating from the decomposing rock.
This can be seen loading Hortons images into the stereo veiwer.

Fram crater looks to be created after the water event.

Jon,
re. reply #28:

"Silt sized particles do not make dunes. If they are aggregated to form sand sized particles then they can. But then they are no longer silt from a sedimentological perspective."

I have to disagree, this is the geology page after all.

Silt does not have to be aggregated to sand sized particles in order to be form/be incorporated into dune-like structures by the wind. There are examples of this all over the world. Here are a few of many links with information and photographs of dunes composed primarily of silt-sized particles. Admit it, they do exist.

[link]

[link]

http://www.bsyse.wsu.edu/saxton/cp3/Papers/Poster/Poster.htm

http://www.carnegiemuseums.org/cmnh/ip/tours/trail/red/5.htm

[link]

[link]

http://geosun.sjsu.edu/paula/134/pdf/lecture20b.pdf

Best regards,
Robert

Thanks mann for the fine X 3D view of the hanging berry! I was going to make the same pun -- but decided to make a more subtle comment. Glad you picked up on it!

Er, just a warning about the color: It's L2/L5/L7 and R1/R2 images, so don't bank on the color. I deliberately balanced the fine, er, gray silt, to grey.

I am busy doing all the other L2/L5/L7 R1/R2 pairs and will try to stitch them onto a color 3D Pan this evening after a social engagement. ( Yes, I actually do have a life away from Mars.)

Robert, why is everyone talking about dunes on this thread???

Reply 55 - I agree with everything except the word 'decomposing'. If you substitute weathering or degrading, that would be better.

That was my first impression too. This is similar to the overlying grey material on the plains. The material is spilling over the edge, and also weathering out of the cliff itself.

Marvin (Horton),

I apologize for temporarily hijacking your thread here. I have continued a portion of my comments regarding the dunes at the base of Endurance on the Endurance Crater's Dazzling Dunes thread in Biology. I will try to behave but I hate to leave those "dunes" behind without further investigation and I may have a slight case of Dune Madness).

Hi horton

Lost of stuff for comment in this discussion. Re post 52:

6)Precipitation is a form of sedimentation. We also know from cross bedding and corss lamination that sand-grade particulate as well as precipitated matter was present in the depositional environment and was subject to reworking. Whether these grains were another silicate or simply reworked eavporites I don't think we yet know.

We know from the fact they displace earlier textures that the spherules formed relatively late during diagenesis. Certianly later than the sedimentary structures and the evaporite pseudomorphs. We don't know at this stage, or at least I don't, whether the basin still contained surface water at the time.

The sphericity of the concretions does not bother me at all. Why should it? First, they are not that spherical, many are irregular, have lumps, bumps, and dimples, some are grooved, others consist of two or three amalgamated together. I know of a great many geological processes that can produce concretions of equal or greater sphericity. Like you I have examples, bauxite pisolites, calcrete pisoliths, ironstone pisoliths that gave grown during acid groundwater diagenesis.

5) I don't see the image as evidence of drage, simply of flat slabs that have fallen down the slope. There is no real consitency in bedding orientation between the slads suggest any genetic continunity in their geometry. Any weathering and eroding slabby rock (slate for example) will cover a slope with randomly orientated slabs in which the bedding will, because of the slabby nature of the rock, be subparallel to the slope.

Re post 53:

4) Your prediction is a valid one for your hypothesis, but is is not a unique solution to the observation. As for my predictions, here are some. a) The cross-bedded unit will be aeolian. b) The darker bands will contain be mineralogically different to the lighter bands, perhaps through containing more haematite, either as concretions of disseminated. c) Evporites will be present throughout the host rock. d) Some of the upper units will display low angle and ripple cross-lamination.

3) OK, I get what you are driving at now. Geometrically it is similar to what gray said in the X-bedding thread. I don't see it myself, but closer inspections should clarify it.

2) I don't see any different between Fram and the other craters except in scale and degree of degradation.

1) Still not quite clear here at what you are saying. But I would not say that this is the last evidence of surface water on mars simply because we have no absolute chornology for mars water yet. These deposits are Hesperian, so they are the middle Epoch in the history of mars, there is evidence for Amazonian water flows, even very recently, so the story of liquid water is still ongoing.

I don't think there is an accepted theory, yet, just multiple working hyptheses which we sift insead of watching TV

Cheers

Jon