HDP Don,
It sounds like you are arguing that all the layers that Opportunity
has seen, and even that the entire 1km stack of layers, are likely
created by base surge events. Do you not allow for a significant
number of these layers being wind-blown deposits?

Going back to what you say in this post:
"All impact spherules are caused by vapor condensation in a hot turbulent cloud.
Specular (blue-gray) hematite typically forms in steamy volcanic fumaroles by
condensation and reaction of volatile Fe-chlorides or other volatile Fe species,
and this is a very similar environment to that in a steamy surge cloud. The
Meridiani difference is that some other sticky condensate must have caused
the hematite flakes to preferentially adhere to each other and other particles,
and grow as a snowball does..."

"[S]ome other sticky condensate must have caused the hematite flakes to
preferentially adhere to each other and other particles..." sounds vague and
wishful. Is there any candidate for this "other sticky condensate"? The
"volcanic fumeroles" example sounds like something that takes time. I still
have a hard time seeing hematite berries forming in a violent, sudden event.
Has this sort of differentiation by condensation been seen in base surge deposits
on Earth or are most or all berry-like features in Earthly base surges similar in
composition to the material surrounding them?

My problem is with seeing such an efficient differentiation of materials ocurring in
such a violent, rapid, and short-lived event. I don't have a problem with differentiation
based on size, but with that based on chemistry. How was virtually all of the hematite
removed from the sulfate materials with which it must have been thoroughly mixed
by impact and recondensed as spherules so rapidly?

Hi Kye,

A web search revealed you as our only defender on that other site a long time ago. Nice to meet you at last and thanks for holding the fort, although I'd be especially interested in discovering why you decided to defend our highly controversial idea at such an early date.

Regarding your specific question about "single particle layers," not being or claiming to be a sedimentologist, I'm probably not the best person to answer it (but that hasn't stopped me yet - why now?). I'll give my reply in two parts: 1) I doubt that such layers could be unambiguously be recognized on MI images of Meridiani sediments, given the amount of salt encrustation. 2) Early Meridiani papers referred, I believe, to "pinstripe lamination" as being diagnostic of eolian deposits. We therefore looked up the original 1988 paper by Fryberger and Schenk in Sedimentary Geology, v. 55, p. 1-15. This referred to pin stripe laminations as "distinctive" and concluded only that "They may prove useful in the recognition of eolian sediments" in the abstract and "may help in identifying rocks of eolian origin" in the conclusions.

Once Knauth had published his first LPSC abstract here:
http://www.lpi.usra.edu/meetings/lpsc2006/pdf/1869.pdf
in which his Fig. 3 was labelled "Pinstripe lamination and low angle cross-bedding in base surge deposits from Kilbourne Hole, NM" the MER team apparently stopped referring to "pinstripe lamination" as proving anything much at Meridiani. Note also his Fig. 2 that shows a Burns Cliff-like high-angle cross-bed (dune-like form) from a surge deposit in the Superstition Mts. about an hour out of Phoenix, and his Fig. 5 that shows Meridiani-like polygonal cracking from a bedding surface at the same locality.

A better answer about "single particle layers" could perhaps be given by Tim Demko. I'm pleased to discover, from his latest post, that we have a real honest-to-God HDP sedimentologist hiding here amongst the sheep. Baaa. Baaa. Baaa. (He doesn't seem to think much of the term "festoon" either, and agrees that cross-beds indicate scouring - something that surges are certainly capable of, far more than the wind.)

--HDP Don

Other Doug,

I'm running out of time to answer all of these questions tonight (my wife just called to find out where I am), so l'll try to be brief. Some types of tuffs are welded ("ignimbrites") usually from non-basaltic types of volcanoes. You wouldn't really expect welded tuffs on Mars. Volcanic surge deposits are characteristically non-welded (else they would never be mistaken for normal sediments), and impact surge deposits on Mars, where the target was probably frozen, could be expected to be even less so. The only welding is by salts, which encrust the grains during "diagenesis" (chemical and physical changes to a sediment that occur just after deposition) - that's also when the larger chloride crystals formed, later to be leached out (perhaps by frost). This encrustation does not require being immersed in water (in which case you would grow truly large crystals and segregate salts by solubility), only moisture and capillarity.

Regarding the hematitic blueberries, they theoretically could form in a number of ways (metal condensates, later oxidized, Fe-rich glass condensates, later oxidized, or Fe-rich accretionary lapilli, later oxidized). The only method that explains why they are the blue-gray or high-temperature form of hematite is if they actually grew in the surge cloud from Fe-chloride vapors and steam, as blue-gray hematite does in fumaroles. They probably condensed and accreted in the particle-poor, gas-rich top of the cloud, not the particle-rich bottom. Once they had reached a certain size, however, they gradually worked their way down through the turbulent cloud (still travelling at perhaps 100's of km per hour) and were deposited with the sand particles as a dissemination. Sorry if that sounds unreasonable to you. Make a better suggestion. Keep in mind that the conventional concretion story absolutely fails to account for the blue-gray nature of the spherules under any circumstances (or their strict size limitation, or their shape, or their failure to clump in masses) - and the blue-gray nature of the hematite in the spherules was the ONLY reason why Meridiani was picked as a landing site (other than being flat and equatorial). As I said in a previous post, picture yourself injecting BB's and sand in the turbulent exhaust of a screaming stationary jet engine (a crude approximation of a surge at some stage in its evolution). Do you really expect them to "sort out"? Read my earlier posts on this topic, and explain why a sedimentary concretion should consist of the high-temperature, blue-gray form of hematite.

As I also said in a previous post, don't confuse salt encrustations on top of spherules, or smoothing and shaping caused by wind, for the spherules themselves.

That's all for now before I have to get a divorce. Try to get to the rest later.

--HDP Don

Doctor Burt, Regarding your reply 108 and my 99: Why did I decide to support your outlandish theory early on? I guess I did something that few bothered to do. I found images of base-surge exposures on the net so I could see what you were talking about. The original brine-splat was not illustrated. Years later I am still answering variations on the objection that "An explosion couldn't produce regular layering", and that objection is apparently still a problem for some on this forum. I do not know HOW surge produces regular layering, and I suspect that this is not well understood by sedimentologists, but one can have no doubt that surge does often create regular stacks of layers if they just look at the pictures.

Also, I am a big fan of Occam. Your explanation isn't just a little simpler than the MER team's, it is an order of magnitude simpler.

I was not referring to pinstripe layering in my reply 99, but to single-particle layers be they thick or thin, that is, layers largely made up of particles with diameters that match the depth of the layer. I take your point that grains may not be reliably distinguished in MIs of the Meridiani sediments, but taking the MER scientists word for it, I have tried to find out more. Single-particle layers are apparently rare in sediments, aeolian sand-sheets being one of the few examples. I suspect that base-surge sediments and perhaps turbidites also hold single-particle layers but I have yet to read anything that discusses this question. I hope that we hear from sedimentologists. Could some of the regularity in thickness in some of the planar beds be contributed by a common large grain size? Are the layers shearing against each other at some time during deposition and being reduced to the minimum thickness that can hold the larger grains? It is a minor question perhaps with so much else to talk about, but the mechanism of surge deposition continues to intrigue me.

Centsworth - Thanks for the excellent question, which allows me to expound a little. No, I have no prejudice against eolian sandstones. In fact, some of my best friends are eolian sandstones. I've made their acquaintance in the Page area, AZ, over the past 3 years, and their names are the Page Sandstone and the lower down Navajo Sandstone. I've learned a lot from those friends, but not what the MER team claimed I might. See previous posts for some of what I've discovered about hematitic concretions, old water tables, flowing water, interdune playas, and so on.

On dry, cold Mars, as I see it, eolian sandstones have had a minor problem for the past 3.8 billion years at least. That problem is that it seems nearly impossible to form them. The basaltic sand forms with no problem (probably some or most of it was rock originally pulverized by impacts) but cementing it into a solid rock is the problem. That requires a long immersion in liquid water. Without that liquid water, the sand grains just blow around and and around, getting a little rounder in shape with each bounce, forming nice dunes, and filling craters such as Endeavor and Victoria partly or completely. The rounded grains act like little ball bearings (I credit Ron Greeley for this idea), making it easier for Oppy to get stuck, as already happened in Purgatory Dune and may happen shortly in Victoria (let's all hope not). If the sand gets buried deeply enough, or arrives near the poles, it may be incorporated into permafrost, but this sandy ice hardly a rock by conventional definitions - an hour in the lab and you'd have a pile of wet sand. Inasmuch as this is my own hypothesis, you will note that I am excluding from consideration the anomalous "Sahara desert oasis" hypothesized by the MER team for giant Meridiani (too many problems).

Well, you say, how do we make a sandstone then? Boom! of course. A big impact will dig up salts and vaporize ice, sending a super-hurricane force surge cloud out radially (with local little tornadoes leaving radial grooves, as described by Sue Kieffer and others for volcanic deposits). The cloud will efficiently scour away any sand or dust it encounters and incorporate it into the cloud - probably until the cloud eventually consists dominantly of such particles. The cloud will override mountains, efficiently scouring the highlands, and will eventually "pond" in a lowland, such as Meridiani or perhaps Gusev Crater, as it loses steam, literally. As salts and then steam condense the sticky sands are deposited (perhaps along with contained condensation-related spherules), and after a few post-depositional changes involving moisture and salts, voila, instant rock. The salt cement would never meet terrestrial construction standards - a little rain or snowmelt and it would rapidly fall apart, as happens to terrestrial impact deposits. On dry cold Mars these rocks seem to last for billions of years, however. In this regard, the famous Mars rampart craters were hypothesized to be erosion-resistant examples of abrupt steam condensation in relatively small and wet surge clouds by Wohletz and Sheridan (1983). The surge hypothesis thus accounts for the rounded sand grains imaged by Spirit's MI in the upper beds of Home Plate without requiring a separate eolian episode (mistaking surge for eolian deposits was the mistake made by Gene Shoemaker at Kilbourne Hole and other volcanic surge deposits in the late 1950's, before he had mapped Meteor Crater for his Ph.D. thesis at Princeton). The surge hypothesis also accounts for the many layered, salty deposits that fill old craters to above their rims (something seemingly impossible with water deposition).

I'm not saying that water- or wind-deposited sandstones might not occur in the lower levels of Meridiani (or in the Northern Plains) - I have no idea what torrential rainstorms or blizzards might have been condensing during the Late or other Heavy Bombardment, or what the transient weather might have been like. I'm just stating that in the 3.8 billion or so cold dry years afterwards, over the long term impact seems to me to be the only process capable of routinely depositing sandstones at higher elevations (absent drainage networks and outflow channels, that is, as at Meridiani).

I eagerly await HDP Demko telling me that there are a dozen other ways to make martian sandstones that I haven't considered. Please go easy on the technical vocabulary though - remember the audience.

BTW, Centsworth, why don't you tell your shy, insecure Australian buddy Jon Clarke to stop singing my praises on that other obscure site and get his two festoons ( UU ) over here ASAP (unless his enthusiasm has already caused him to be banned from this site). We HDP's have enormous egos that require constant stroking and I look forward to basking in his adulation. Tell him I'll give him a penny for his thoughts.

--HDP Don

HDP Don,
Tell me again why you're having trouble making friends
and influencing people in the scientific establishment?

You're still wrong; in fact, so wrong that trying to convince otherwise is a wasted effort.

I think some of you are being way too antagonistic. Do you not realize that we all have a special opportunity here to have a conversation with a scientist who publishes in major journals, and who is smack dab in the middle of a major planetary debate? How many other such researchers do you see coming out into the open, to publicly discuss their ideas so openly?

We are very fortunate that this forum encourages such communication. Personally, I disagree with a number of Dr. Burt's ideas regarding Meridiani, but others of his thoughts ring a bell with me. I think I will continue to sit in the back row and listen.

Agreed, CR. While I am nowhere near knowledgable enough to participate in this debate, I treasure the fact that UMSF is a forum of choice for this dialogue.

And, just to reset the baseline here, let's not forget that Mars is an alien planet--not Earth--and alternative hypotheses to explain our obviously biased early observations should therefore be explored to the fullest. (Come to that, look at the full spectrum of gradual vs. catastrophic hydrological/stratigraphic events in Earth's geological record...who's to say that Mars' history is any less complex? Definitely insufficient data at this time to state otherwise.)

Viva free thinking, viva free exchange of opinions! Maybe it's just the US 4 July spirit speaking here (or other spirits, I confess... ), but, boy, is it great to see this sort of debate free of meetings, inevitable personal grandstanding/filibusters & ancilliary agendas. After all, what does Prof. B have to fear from all us Internet ghosts in terms of professional issues? Press on, gentlemen, press on!

Whoa!! Careful, Bill. You're getting positively verbose! Sixteen words of dismissal, instead of just three. Next time you might even include an argument or two!

OK

--Bill

First, I like some of your ideas; but in the case of Meridiani, the evidence so far does not support your hypothesis. Another major problem is that the sandstones at Meridiani are MUCH harder deposits than what you claim would be created by an impact surge. The rover is fairly heavy. It has driven over these sandstone deposits many times. If they were as soft as you claim, then they would have crumbled. The only time the rover makes track marks is when it drives over loose or dune like crusty soil. The hard stuff underneath is a layered deposit that is not marked up unless the MER team uses the RAT tool. Your hypothesis does not account for its observed durability. If it were made as you suggest, then the RAT tool would have sliced through it like butter. The only possibility is that these hard layers were wet at some point.

In the second part that I quoted, you seem to be indirectly contradicting yourself slightly. If torrential rainstorms were possible, then why not directly at Meridiani? The Mars crust has shown through computer models to have significantly deformed with the shifting of the poles.

Low areas could easily gain altitude over the billions of years that passed. And if there was a lot of water, then capillary action could easily extend these dune like formations as they captured the blowing dust. Eventually the process would end and the formation of normal dunes on the surface would occur. Meters below the surface, the groundwater could easily morph the rocks further. Eventually the groundwater itself would either recede or freeze. With the water no longer in contact with the surface atmosphere, different types of brine could easily form over time depending on the circumstances. So far, we have an incomplete water record. We cannot be sure of all the circumstances. That's why it is so important for Opportunity to descend into Victoria as deep as possible. The best record should be revealed within days or weeks.

It's possible that that record will support your hypothesis; I just doubt it considering all that has been discovered up to now. I am willing to keep an open mind.

To change my mind, there must be a number of critical discoveries inside Victoria. The Pans of the inside of the crater suggests a similar story as the MER team has pictured. The story will likely change again slightly. But that is not a problem.

The MER team never stated how much water was on the surface. During interviews they stated the parameters were wide. When asked whether this body of water could have been a sea, they said it was possible but they didn't know. The press ran with the story that they found evidence of seas. Recently they simply narrowed the parameters. Their basic idea has not changed. You suggested that it had. That's why you got the confrontation. You seem to suggest that the MER team has not seriously considered the type of morphology that you currently propose. I would argue that they have and ruled it out. At times when discussing here you seem to have belittled their arguments--although I'm sure that was not your intent.

I appreciate your coming to this forum to discuss alternatives. Even if the evidence does not fit here at Meridiani, these ideas are still relevant. I particularly see possible evidence of what you are talking about at Gusev. The missing piece is Spirit finding a lot more examples of sulfides. Yet, even observed evidence at Gusev suggests further alteration after what appears Could have been impact surge.

Like I said, the story is complex. I personally don't think everything shut down after bombardment. I believe that Mars is dynamic even today. It is just not nearly as dynamic as Earth. Very recently and not necessary published, we are currently seeing the dynamic nature of Mars...the dust storms, the sudden change in the tracks with the sudden increase in wind (never before seen, until just days ago), the massive observed changes at Gusev with the impact of dust devils. Stuff moves around Mars a lot more quickly then we first thought. It just appears to happen in bursts.

It would be helpful to the rest of us if you would pick a point that the professor has made,
either to disprove the MER team theory or support his own, and make your case against
it. HDP Burt may not be convinced, but the purpose of this type of forum is to educate and
convince the rest of us.

Unfortunately, despite all the science, it is this which stands out the most. Going on to belittle this place and those that visit it and run it was also totally unnecessary. It is a pity HDP feels the need to pitch his hypothesis this way, whatever its merits might be.

Doug