Alternate Theory for Meridiani Layering

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centsworth_II

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I don't remember seeing any discussion of this at SDC. I'm wondering <br />if anyone here, particularly Jon Clarke, has some thoughts about it.<br /><br /><i>"The site where the Mars Exploration Rover Opportunity landed has sediments <br />and layered structures that are thought to be formed by the evaporation of an <br />acidic salty sea....However, ASU geologists L. Paul Knauth and Donald Burt, who <br />along with Kenneth Wohletz of Los Alamos National Laboratory, say that base <br />surges resulting from massive explosions caused by meteorite strikes offer a <br />simpler and more consistent explanation for the rock formations and sediment <br />layers found at the Opportunity site."</i> <br />http://www.asu.edu/news/stories/200512/20051222_mars_meteorites.htm<br /><br />More papers on the above-mentioned theory: <br />http://www.lpi.usra.edu/meetings/lpsc2007/pdf/1922.pdf<br />http://www.lpi.usra.edu/meetings/lpsc2007/pdf/1757.pdf<br />http://www.unmannedspaceflight.com/index.php?act=Attach&type=post&id=10957<br /><br />One of the authors of this theory, Donald Burt, is currently responding<br />to questions and comments in this thread at unmannedspaceflight.com <div class="Discussion_UserSignature"> </div>
 
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JonClarke

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What do I think about it? This <img src="/images/icons/rolleyes.gif" /> <br /><br /><img src="/images/icons/smile.gif" /><br /><br />Jon<br /> <div class="Discussion_UserSignature"> <p><em>Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars</em>  Arthur Clarke</p> </div>
 
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3488

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I take it that you are not convinced Jon?<br /><br />I am not sure, but this is getting more & more complicated for sure.<br /><br />Interesting reads though, thanks centsworth_II for<br />posting them.<br /><br />Andrew Brown. <div class="Discussion_UserSignature"> <p><font color="#000080">"I suddenly noticed an anomaly to the left of Io, just off the rim of that world. It was extremely large with respect to the overall size of Io and crescent shaped. It seemed unbelievable that something that big had not been visible before".</font> <em><strong><font color="#000000">Linda Morabito </font></strong><font color="#800000">on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.</font></em></p><p><font size="1" color="#000080">http://www.launchphotography.com/</font><br /><br /><font size="1" color="#000080">http://anthmartian.googlepages.com/thisislandearth</font></p><p><font size="1" color="#000080">http://web.me.com/meridianijournal</font></p> </div>
 
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JonClarke

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Hi Andrew<br /><br />The basic problem with it is that, while not completely impossible it is just very unlikely and it is certainly not parsimonious.<br /><br />The standard view for the Meridiani succession is that the sediments represent mosaic deposition from very shallow and often dessicating saline lakes and associated dunes, fed by groundwater. In my part of the world we call these boinkas. I suggested to Steve Squyres a couple of years back that he should start using this word, but so far no sign <img src="/images/icons/smile.gif" />. The evidence for this includes: parallel lamination, indicative of very shallow water, current ripples, indicating slightly deeper water with significant flow, mud cracks, indicating desiccation, and sulphate rosettes indicating salt growth in saturated conditions. The steep crossed bedded units are the result of aeolian deposition on the edges of the lakes. The blueberries, like the haematite veins, are the result of diagenesis, as they cross cut the depositional and early diagenetic features. These are very well understood processes and associations from earth and very few geologists have any problem with this.<br /><br />As I understand them, Burt and his associates are argue that the Meridiani succession can be explained by base surge deposits into a water-saturated environment. They argue that parallel lamination, cross-bedded, and ripples can all be found in base surge deposits known from terrestrial volcanic environments. This is true by the way. They argue that the base surges at Meridiani were not volcanic, but the result of impacts. The blueberries are accretionary lapelli. I have several problems with this.<br /><br />First, for their mechanism to work you need a water saturated environment to start with. In other words something very like the shallow to dry lake that is the main interpretation of Meridiani (note that almost all dry lakes are actually moist beneath the surface because of groundwater discharge). So their <div class="Discussion_UserSignature"> <p><em>Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars</em>  Arthur Clarke</p> </div>
 
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centsworth_II

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My poor brain is in overload from trying to keep up with all the facts <br />and arguments. A few off-the-top-of-my-head reactions, Based, of <br />course, on my imperfect understanding of D. Burt's arguments:<br /><br /><font color="yellow">"The standard view for the Meridiani succession is that the sediments represent <br />mosaic deposition from very shallow and often dessicating saline <br />lakes and associated dunes, fed by groundwater.... The evidence for this <br />includes... current ripples, indicating slightly deeper water with significant flow..."</font><br />D. Burt asks how "significant flow" happens on flat land, and says that no signs<br />of flow channels have been seen in Meridiani.<br /><br /><font color="yellow">"...even on Mars, impacts are relatively rare. In any given sedimentary succession <br />we should only expect to find a few impact deposits. However at Meridiani we have <br />dozens of depositional units. It seems unlikely that these are all base surge deposits."</font><br />D. Burt says a lot of base surge deposits were laid down during a "late heavy<br />bombardment" period -- lots of impacts -- with the surface of Meridiani <br />coinciding with the end of this period. <br /><br /><font color="yellow">"Accretionary lapelli are composed of the same material as the surrounding material."</font><br />Interesting. I don't recall if the reason why the "acretionary lapelli" would be of a<br />different material in Meridiani has been posed to D. Burt. <br /><br /><font color="yellow">"...the Burt et al. story... forces people to think outside the box..."</font><br />My brain hurts!<br /><br /><br /><br /><br /> <br /><br /><br /><br /><br /><br /> <div class="Discussion_UserSignature"> </div>
 
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JonClarke

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Picking up some of your main points:<br /><br /><font color="yellow">"The standard view for the Meridiani succession is that the sediments represent mosaic deposition from very shallow and often dessicating saline lakes and associated dunes, fed by groundwater.... The evidence for this includes... current ripples, indicating slightly deeper water with significant flow..."</font><br /><br />D. Burt asks how "significant flow" happens on flat land, and says that no signs of flow channels have been seen in Meridiani.<br /><br />Me: First of all, for their hypothesis to work, Burt et al need a wet, salty, sedimentary target environment and a wet, salty depositional environment. If lack of channels is a problem for explaing the sediments as lake deposits it has to be equally a problem for their hypothesis as they need a lake or other saline flat for their model to work. If I understand them correctly.<br /><br />Second, in terrestrial lakes with inflow channels, the channel is such a small part of the overall environment that the probability of seeing it in the geological record is small. If the lack of visibility of such a channel is a fatal blow for the lake hypothesis, then it is equally a fatal blow to the interpretation of most ancient lake deposits on earth.<br /><br />Third, the suggested origin of these lakes is not through overland flow through channels but by groundwater discharge. These lakes not need channels. There are cores if not hundreds of such lakes in the boinkas of southeast Australia. Each lake has its own chemistry, varying from fresh neutral to acid saline.<br /><br />Fourth, you don't need channels to get fast flows. Wind driven currents in shallow lakes and lagoons can flow fast enough to generate current ripples across large expanses.<br /><br /><font color="yellow">"...even on Mars, impacts are relatively rare. In any given sedimentary succession we should only expect to find a few impact deposits. However at Meridiani we have dozens of depo</font> <div class="Discussion_UserSignature"> <p><em>Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars</em>  Arthur Clarke</p> </div>
 
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3488

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Thanks Jon & centsworth_II for your answers.<br /><br />I was not sure, but the article made for interesting reading.<br /><br />i agree, that Meridiani, without a doubt was the bed of a shallow sea & or a series of large<br />interconnecting lakes.<br /><br />Mars is a real quandry. We have a planet, which has had a much denser & warmer atmosphere,<br />active aerology as well as being bombarded in the past,<br />a hybrid between the Earth & Moon.<br /><br />Perhaps the truth is somewhere in between.<br /><br />Anatolia seen near the start of Opportinity's mission, I know you had answered that as a <br />mud crack. High resolution images from MRO HiRISE & MGS MOC, show the whole area has many<br />such features. <br />The area was very wet at one time, then went through wet & dry episodes, causing cracking, before<br />becoming cold, arid & permanently dry.<br /><br />Pehaps when or if Opportunity gets into Victoria Crater & / or pushes on to Ithaca Crater<br />we will know for sure.<br /><br />Did Endurance Crater not settle this, particulalrly the layering at Burns Cliff?<br /><br />Fascinating time we are living in.<br /><br />Andrew Brown. <div class="Discussion_UserSignature"> <p><font color="#000080">"I suddenly noticed an anomaly to the left of Io, just off the rim of that world. It was extremely large with respect to the overall size of Io and crescent shaped. It seemed unbelievable that something that big had not been visible before".</font> <em><strong><font color="#000000">Linda Morabito </font></strong><font color="#800000">on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.</font></em></p><p><font size="1" color="#000080">http://www.launchphotography.com/</font><br /><br /><font size="1" color="#000080">http://anthmartian.googlepages.com/thisislandearth</font></p><p><font size="1" color="#000080">http://web.me.com/meridianijournal</font></p> </div>
 
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JonClarke

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Hi Andrew<br /><br />I suspect the Anatolia cracks, which are very large, open features, are relatively recent features due to movement of the modern surface. As Opportunity left Endurance it passed some large pits that could have been collapse pits, but unfortunately did not stop for a look.<br /><br />Is Ithaca the very large crater in this distance? <br /><br />Jon <div class="Discussion_UserSignature"> <p><em>Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars</em>  Arthur Clarke</p> </div>
 
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3488

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Hi Jon,<br /><br />Ithaca Crater AKA Big Crater is perhaps 20 kilometres away, to the south. It is a huge crater. Perhaps<br />20 - 25 KM across.<br /><br />I dont know though, if Victiria Crater is 800 metres across, Ithaca Crater looks larger <br />than 25 KM across?<br /><br />I need to look at the images that you have referred to. Could well be, a raised rim if tall enough<br />as you know will be visible from well over the horizon.<br /><br />Very deep also, perhaps varying bewtween 200 metres to perhaps 1,500 metres deep.<br /><br />Makes Victoria Crater look a very small pit indeed.<br /><br />If this option is taken, looks like there may be a slight detour on route <br />to Mini Endurance Crater.<br /><br />Thank you for your answer about Anatolia. I wonder how long & what caused them to form?<br /><br />I know, I am full of questions, but am seriously interested in this.<br /><br />Andrew Brown. <div class="Discussion_UserSignature"> <p><font color="#000080">"I suddenly noticed an anomaly to the left of Io, just off the rim of that world. It was extremely large with respect to the overall size of Io and crescent shaped. It seemed unbelievable that something that big had not been visible before".</font> <em><strong><font color="#000000">Linda Morabito </font></strong><font color="#800000">on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.</font></em></p><p><font size="1" color="#000080">http://www.launchphotography.com/</font><br /><br /><font size="1" color="#000080">http://anthmartian.googlepages.com/thisislandearth</font></p><p><font size="1" color="#000080">http://web.me.com/meridianijournal</font></p> </div>
 
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JonClarke

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Ah, that is the one I thought it was. I don't suppose the rover will make it there. But then, Victoria crater seemed impossibly far away before. And Endurance before that. So who knows? <img src="/images/icons/smile.gif" /><br /><br />Goodnight!<br /><br />Jon <div class="Discussion_UserSignature"> <p><em>Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars</em>  Arthur Clarke</p> </div>
 
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3488

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Of course, Good Night Jon.<br /><br />If this option is taken, I would not at all be surprised that Opportunity would make it.<br /><br />Both MERs have accomplished far more than expected pre arrival. I still think there is much life in <br />both of them yet.<br /><br />Andrew Brown. <div class="Discussion_UserSignature"> <p><font color="#000080">"I suddenly noticed an anomaly to the left of Io, just off the rim of that world. It was extremely large with respect to the overall size of Io and crescent shaped. It seemed unbelievable that something that big had not been visible before".</font> <em><strong><font color="#000000">Linda Morabito </font></strong><font color="#800000">on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.</font></em></p><p><font size="1" color="#000080">http://www.launchphotography.com/</font><br /><br /><font size="1" color="#000080">http://anthmartian.googlepages.com/thisislandearth</font></p><p><font size="1" color="#000080">http://web.me.com/meridianijournal</font></p> </div>
 
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JonClarke

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Closing thought.<br /><br /><b>Come, my friends,<br />'Tis not too late to seek a newer view.<br />Push off, and driving well in order cross<br />The endless dunes; for my purpose holds<br />To drive beyond the landing ellipse, and the <br />etched terrain, until the rover dies.<br />It may be that the sand will bog us down:<br />It may be we shall touch the distant rim,<br />And see the great unconformity, of which we dreamed.<br />Tho' much is taken, much abides; and though<br />The rover has not that strength which in old days<br />Traversed plains and climbed crater walls; that which we are, we are;<br />One equal temper of heroic hearts,<br />Made weak by time and fate, but strong in will<br />To strive, to seek, to find, and not to yield.<b><br /></b></b> <div class="Discussion_UserSignature"> <p><em>Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars</em>  Arthur Clarke</p> </div>
 
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centsworth_II

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Much discussion has been devoted to Ithaca in unmannedspaceflight.com<br />(UMSF). I can't remember if Big Crater, Ithaca, or both are names given by <br />UMSF members as opposed to official names. As far as getting there is,<br />concerned, I think the consensus is that it would be better to take the route<br />in yellow and avoid some rough dune area evident over the blue route.<br /><br />But back to base surge... Ithaca's creation would have kicked up some serious<br />dirt! Whether as fallout or base surge, I wonder where these sedimentary <br />layers might be: Above the current Meridiani surface and long ago eroded away,<br />or deep beneath Victoria? I wonder if there is any hope of ever knowing?<br /><br /> <div class="Discussion_UserSignature"> </div>
 
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JonClarke

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Ithica would cerainly have had a big splat when it hit and covered the rover site. But of course we don't know when this happened and if any of the ejecta is preserved or exposed. It might even predate the sediments and the rim could be composed of rocks poking up through cover, rather as the Columbia Hills do. <br /><br />In fact the ejecta from craters thin dramatically as you go away from them. You really have to look carefully to find evidence for the The KT event and Acraman event more than a few crater diameters away from the site.<br /><br />Jon <div class="Discussion_UserSignature"> <p><em>Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars</em>  Arthur Clarke</p> </div>
 
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centsworth_II

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Jon,<br /><br />In D. Burts's latest post, he summarizes his understanding of the MER <br />team's theory. He is as skeptical of their theory as you are of his. I'm <br />wondering if you see any valid points to his skepticism. <div class="Discussion_UserSignature"> </div>
 
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JonClarke

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The short answer is - no.<br /><br />The longer answer is his summary fails to summarise and is full of pointless sarcasm and strawmen.<br /><br />Burt et al. have nailed their colours to the mast and I don't think they are likely to change their views on this any time soon. So of course have Grotzinger et al.<br /><br />In the end it will come down to how they convince their peers. So far Burt et al. have not done a good job of this and others are still sitting on the fence waiting for more data. We will see what story Victoria tells.<br /><br />On a broader context I do think the Burt et al story is part of a rear guard action by a mind set that wants Mars to be dry and windy and refuses to recognise the evidence for widespread liquid water in the past.<br /><br />Jon<br /><br /> <div class="Discussion_UserSignature"> <p><em>Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars</em>  Arthur Clarke</p> </div>
 
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JonClarke

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OK, here is my detailed thoughts on Burt’s post here.<br /><br />I have edited out some irrelevant comments for brevity. <br /><br /><i>Meridiani is not much of a topographic basin, and there are no early drainage networks or other signs of liquid water leading towards it or away from it (e.g., no alluvial fans or deltas near its edge, no exit channels) so they had to assume (at least in their second iteration) that acid, salty waters mysteriously rose out of the ground, forming an enclosed playa lake (now mysteriously vanished, although they seem to see no logic problems with having it still somewhere underneath - see my other post) that then evaporated to precipitate abundant salts at the surface, both highly soluble and nearly insoluble, and neutral and acid (jarosite).</i><br /><br />The sediments preserved are an eroded remnant. The topographic basin may no long be detectable. This is the case with a great many terrestrial sediments.<br /><br />The absence of feeder channels is both a straw man and false. It is a strawman because you don’t need to preserve the channels to know you have a lacustrine deposit. A great many volcanic deposits on Earth have no known feeder or volcanic centre. Does that mean that they are not volcanic centre? We have terrestrial impact deposits without known impact craters. Are these therefore not impact deposits?<br /><br />It is false because, despite the sarcasm, groundwater fed saline lakes are common on Earth. It is not something mysterious at all.<br /><br /><i>In evaporation of any real playa lake, the salts would form bathtub rings according to solubility, with the least soluble ones on the outside, but this problem was not explicitly considered, I believe.</i><br /><br />In a great many real playa lakes there is not a well defined bathtub ring of salts. Furthermore <div class="Discussion_UserSignature"> <p><em>Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars</em>  Arthur Clarke</p> </div>
 
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JonClarke

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Attached is an image of Pinjarra Lakes in Western Australia. I had a student working on them a few years ago. The image is from Google Earth, and is 15 km wide. Some points worth noting.<br /><br />The topographic basin is very poorly defined and, in an ancient example, might well be unrecognisable.<br /><br />The lakes have no channels of any note leading into them. It is fed entirely by groundwater and rainfall. The groundwater is underpressure and wells up through the lake bed and in specific springs. The water is weakly acid.<br /><br />The lake sediments are muds and sands, locally rippled, bust mostly flat laminated.<br /><br />Each lake has a different chemistry and history. Some are just sand and/or mud flat, some are relict but floored by gypsum, some vegetated, some are actively precipiating gypsum, and some have thick salt crusts. One spring is precipiating iron hydroxides and jarosite.<br /><br />The dunes are of two types. The longitudinal NW-SE dunes are part of the regional dunefield of the Grerat Victoria desert, the largest sand sea in Australia. They are composed of reddish quartz sand. The greyish transverse dunes and lunettes are associated with the lakes. They are formed of quarts sand, clay particles and gypsum that have been blown of the lakes. Some of these are actively forming, some are relcit and eroded. Some have buried older lake deposits.<br /><br />This is a typical example of a groundwater discharge complex or boinka. I think it is a good analogue for what has been postulated for Meridiani.<br /><br />Jon<br /><br /> <div class="Discussion_UserSignature"> <p><em>Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars</em>  Arthur Clarke</p> </div>
 
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kelvinzero

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Hi, sorry to butt in with an off topic question,<br />where do the terms Whatanga Contact and Wellington Contact come from? (they both happen to sound New Zealandish)
 
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JonClarke

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They do don't they?<br /><br />I am not sure of their origin. I can check next week when I am back at work and have access to the relevant papers.<br /><br /><br />As far as I know none of the main researchers have a Kiwi connection.<br /><br />Jon<br /> <div class="Discussion_UserSignature"> <p><em>Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars</em>  Arthur Clarke</p> </div>
 
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centsworth_II

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<font color="yellow">"...I do think the Burt et al story is part of a rear guard action by a <br />mind set that wants Mars to be dry and windy..."</font><br /><br />I don't know why anyone would want that. I don't. But I also<br />want what is "known" to be the truth. Besides, as you said,<br />their theory requires impacts to occur on the surface of a wet Mars.<br /><br />Professor Burt provided a reference on surge deposits here: <br />http://www.ees1.lanl.gov/Wohletz/Pyroclastic%20Surges.pdf<br />What strikes me is the similarities between the diagrams and<br />what the rovers are seeing. Of course a text on layers deposited<br />by running water would also show similarities to the MER images.<br /><br />But I can understand how those who did such research long before<br />the MER mission would look at the MER images and say, 'whoa! My<br />research predicted that!" <br /><br /><br /><br /><br /><br /> <div class="Discussion_UserSignature"> </div>
 
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JonClarke

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<i>I don't know why anyone would want that. I don't.</i><br /><br />I find it hard to understand too. Most people don't think that way as far as I can tell, but the ideas still keep popping up. The dreaded Jeff Bell illustrated this some time back in a couple of his op eds. But I don't want to get sidetracked into what was an offhand passing comment. James Kargel has writtene xtensively on this in his entertaining book "Mars, a warmer wetter planet"?<br /><br /><i>But I also want what is "known" to be the truth.</i><br /><br />Don't we all?<br /><br /><i>Besides, as you said, their theory requires impacts to occur on the surface of a wet Mars.</i><br /><br />Exactly, and that is the huge flaw in their argument. they want there to be a wet environment, but it to leave almost no signature except the mineralogy.<br /><br />Now as to that link, where is it from, do you know? It's a chapter out of a book, but which one?<br /><br />With the examples of cross bedding that you showed, as they are not numbered, I'll call them 1-8 from the top down.<br /><br />The only ones I have definitely seen in the Meridiani images are 1, 3, and 8. of these 1 and 8 are fairly generic and form in a great many ways. they are not particular diagnostic of anything. Example 3 is almotsly ways formed by flowing water, I have not seen it in any base surge deposit I have seen personally, and it is very rarely reported in the literature.<br /><br />Examples 2, 4, 5, 6, 7 are very indicative of base surge deposits, I have not seen any examples form Meridiani. <br /><br />This is not strong evidence for base surge. It is very weak evidence for one, and much stronger evidence for playa deposition..<br /><br />Jon <div class="Discussion_UserSignature"> <p><em>Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars</em>  Arthur Clarke</p> </div>
 
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JonClarke

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I will likewise number those columns from left to right as 1-4. of these:<br /><br />Example 1 (explosion breccia) is a definitive indicator of an explosive volcanic eruption or impact. But we do not see it at Meridiani.<br /><br />We do see examples 2-4 at Meridiani. But, by themselves, not particularly indicative of anything, they form in a wide range of environments. <br /><br />When interpreting sedimentary structures it is not just the individual examples that are important, but the whole picture. <br /><br />In a surge deposit we would expect antidunes, consisten flow directions, breccias, and bombs. We don't see any of these.<br /><br />In a surge deposit we would not expect to see common wave and current ripples, mudcracks, evaporite casts,as you would expect in a lake or sand flat deposit. We do see these at Meridiani.<br /><br />If it were a a multiple surge deposit we would see multiple diagnostic successions of surges. Wr don't see that. Instead we see a vertical succession containg the diagnostic features of lake deposits.<br /><br />If it were a a single surge deposit we could not see multiple internal breaks in the succession. But we do. It is not a single depositional sequence. <br /><br />I am sorry, the Burt et al. story makes no sense to me at all.<br /><br />Jon<br /><br /> <div class="Discussion_UserSignature"> <p><em>Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars</em>  Arthur Clarke</p> </div>
 
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centsworth_II

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<font color="yellow">"...as to that link, where is it from, do you know? It's a chapter out of a book, <br />but which one?"</font><br /><br />The title page is the next to last page of the link (the last page is blank).<br />The book, From Magma To Tephra , is described at the publisher's web site:<br /> elsevier.com. Thinking of picking up a copy for yourself?<img src="/images/icons/wink.gif" /> <br /><br />It's natural for any researcher to view new observations, even in different fields,<br />through the prism of his research. Sometimes this leads to new revelations, <br />often it leads to blind ends. But it is an important activity. I don't ascribe any <br />sinister motives on the part of "base surge" researchers in promoting the idea<br />that their observations may have some relevance to the MER data. On the <br />surface, it seems quite reasonable to me -- a total novice to geology.<br /><br />Most, I think, myself included, would, from an emotional standpoint, find the <br />MER researchers' view of what happened at Meridiani to be the most <br />satisfying theory. It puts us face to face with water's handiwork. The surge <br />theory still involves water, but puts us one step removed by the violent <br />processes of volcanism or impact.<br /><br />It's interesting that surge and non-surge proponents seem to me to be on <br />the same page when it comes to what to look for next: clays. It seems to <br />me that the presence of clays as determined by satellite data will be a big <br />factor in choosing MSL's landing place. <br /><br /> <br /><br /><br /><br /> <div class="Discussion_UserSignature"> </div>
 
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