Clays, Not Water, Are Likely Source of Mars ‘Lakes’


Clays, Not Water, Are Likely Source of Mars ‘Lakes’

Ice sheets at Mars’ south pole
This image taken by NASA’s Mars Reconnaissance Orbiter shows ice sheets at Mars’ south pole. The spacecraft detected clays nearby this ice; scientists have proposed such clays are the source of radar reflections that have been previously interpreted as liquid water.Credits: NASA/JPL-Caltech/University of Arizona/JHU

Three studies published in the past month have cast doubt on the premise of subsurface lakes below the Martian south pole.

Where there’s water, there’s life. That’s the case on Earth, at least, and also why scientists remain tantalized by any evidence suggesting there’s liquid water on cold, dry Mars. The Red Planet is a difficult place to look for liquid water: While water ice is plentiful, any water warm enough to be liquid on the surface would last for only a few moments before turning into vapor in Mars’ wispy air.

Hence the interest generated in 2018, when a team led by Roberto Orosei of Italy’s Istituto Nazionale di Astrofisica announced they had found evidence of subsurface lakes deep below the ice cap at Mars’ south pole. The evidence they cited came from a radar instrument aboard the ESA (European Space Agency) Mars Express orbiter.

Colored dots represent sites where bright radar reflections have been spotted
The colored dots represent sites where bright radar reflections have been spotted by ESA’s Mars Express orbiter at Mars’ south polar cap. Such reflections were previously interpreted as subsurface liquid water, but their prevalence and proximity to the frigid surface suggest they may be something else.Credits: ESA/NASA/JPL-Caltech

Radar signals, which can penetrate rock and ice, change as they’re reflected off different materials. In this case, they produced especially bright signals beneath the polar cap that could be interpreted as liquid water. The possibility of a potentially habitable environment for microbes was exciting.

But after taking a closer look at the data, along with experiments in a cold laboratory here on Earth, some scientists now think clays, not water, might be creating the signals. In the past month, a trio of new papers have unraveled the mystery – and may have dried up the lakes hypothesis.

Isaac Smith of Toronto’s York University
Isaac Smith of Toronto’s York University bundled up while working in a lab, freezing smectite clays with liquid nitrogen to test how they respond to radar signals. The results have challenged the hypothesis that subsurface lakes can be found at Mars’ south pole.Credits: York University/Craig Rezza

A Scientific Ecosystem

Gatherings like these provide an opportunity to test new theories and challenge each other’s perspectives. “Communities can generate their own little scientific ecosystems,” said Jeffrey Plaut of NASA’s Jet Propulsion Laboratory, one of the scientists who traveled to the conference. He’s also the co-principal investigator, along with Orosei, of the instrument behind the intriguing radar signals, called MARSIS, or the Mars Advanced Radar for Subsurface and Ionospheric Sounding. “These communities can be self-sustaining,” he continued, “because you bounce a question off someone and maybe a year or two later they help you figure out an answer.”

Martian polar scientists belong to a small, tight-knit community. Not long after the lakes paper was published, about 80 of those scientists met for the International Conference on Mars Polar Science and Exploration in Ushuaia, a seaside village at the southern tip of Argentina.

Lots of talk centered on the subsurface lakes. How much heat would it take to keep water liquid under all that ice? Could brine be lowering the freezing point of the water enough to keep it liquid?

Of course, it wouldn’t be the first time an exciting water-related hypothesis set off a flurry of investigations. In 2015, NASA’s Mars Reconnaissance Orbiter found what looked like streaks of damp sand running down slopes, a phenomenon called “recurring slope lineae.” But repeated observations using the spacecraft’s HiRISE – or High-Resolution Imaging Science Experiment – camera have since revealed this is more likely the result of sand flows. A paper released earlier this year found many recurring slope lineae after a global dust storm on Mars in 2018. The finding suggested that dust settling on slopes triggers sand flows, which, in turn, expose the darker subsurface materials that give the lineae their distinctive coloration.

As with the damp-sand hypothesis, several scientists began thinking up ways to test the subsurface-lakes hypothesis. “There was a feeling that we should try to address this,” said Isaac Smith of York University in Toronto, who organized the conference in Ushuaia and led the most recent study showing that clays can explain the observations.

Too Cold for Lakes

Among those scientists was Plaut. He and Aditya Khuller, an Arizona State University doctoral student who was interning at JPL, analyzed 44,000 radar echoes from the base of the polar cap across 15 years of MARSIS data. They turned up dozens more bright reflections like the ones in the 2018 study. But in their recent paper published in Geophysical Research Letters, they found many of these signals in areas close to the surface, where it should be too cold for water to remain liquid, even when mixed with perchlorates, a kind of salt commonly found on Mars that can lower the freezing temperature of water.

Two separate teams of scientists then analyzed the radar signals to determine whether anything else could be producing those signals.

Carver Bierson of ASU completed a theoretical study suggesting several possible materials that could cause the signals, including clays, metal-bearing minerals, and saline ice. But York University’s Isaac Smith, knowing that a group of clays called smectites were present all over Mars, went further in a separate, third paper: He measured smectite properties in a lab.

Smectites look like ordinary rock but were formed by liquid water long ago. Smith put several smectite samples into a cylinder designed to measure how radar signals would interact with them. He also doused them with liquid nitrogen, freezing them to minus 58 degrees Fahrenheit (minus 50 degrees Celsius) – close to what they would be at the Martian south pole.

“The lab was cold,” Smith said. “It was winter in Canada at the time, and pumping liquid nitrogen into the room made it colder. I was bundled up in a hat, jacket, gloves, scarf, and a mask because of COVID-19. It was pretty uncomfortable.”

After freezing the clay samples, Smith found their response nearly perfectly matched the MARSIS radar observations. Then, he and his team checked for clays present on Mars near those radar observations. They relied on data from MRO, which carries a mineral mapper called the Compact Reconnaissance Imaging Spectrometer, or CRISM.

Bingo. While CRISM can’t peer through ice, Smith found smectites scattered in the vicinity of the south pole’s ice cap. Smith’s team demonstrated that frozen smectite can make the reflections – no unusual amounts of salt or heat are required – and that they’re present at the south pole.

There’s no way to confirm what the bright radar signals are without landing at Mars’ south pole and digging through miles of ice. But the recent papers have offered plausible explanations that are more logical than liquid water.

“In planetary science, we often are just inching our way closer to the truth,” Plaut said. “The original paper didn’t prove it was water, and these new papers don’t prove it isn’t. But we try to narrow down the possibilities as much as possible in order to reach consensus.”

More About MRO

To read more about the Mars Reconnaissance Orbiter, visit:

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August 2, 2021 2:41 am

Do you think some climate science could be wrong too??
Surely not.

Reply to  Alastair Brickell
August 2, 2021 4:05 am

No water, no Mars human’s inhabited base. It may be that Elon Musk is wasting his money.

Nick B
Reply to  Vuk
August 2, 2021 6:59 am

Wrong. Elon Mask is wasting taxpayers money.

Reply to  Nick B
August 2, 2021 8:01 am

No. Government is wasting taxpayers’ money.

Reply to  Vuk
August 2, 2021 2:03 pm

Vuk, I think some of the rovers have discovered water ice just below the surface, certainly at higher latitudes. So quite probably water on Mars, but just not as a liquid.

Next question though is just how much should anyone like Musk be allowed to use to make his methane fuel and how much should be reserved for future generations of colonists to drink and grow food with? This will probably play out first on the Moon with the Chinese and Americans very keen to get to the (hoped for) water at the south polar region.

Maybe in the decades to come Musk and others will develop even bigger rockets (think Starship Heavy or Heavy Heavy) and it will be economic to take enough fuel to Mars for the return trip.

Reply to  Alastair Brickell
August 2, 2021 4:05 am

Do you think some climate science could be right?

Its predictions about more severe weather events are certainly coming true…

Reply to  griff
August 2, 2021 4:20 am


Reply to  griff
August 2, 2021 4:23 am

How many people died in the London floods of 1928, griff?

And how many died this in this year’s flood?

More severe? You shouldn’t take The Guardian seriously, it’s a 6th form rag.

Do you think some climate science could be right?

When it doesn’t involve computer models and tortured data there is a good chance of being right. If the results [of the experiment(s)] can be replicated it stands a very good chance, right?

Last edited 1 year ago by strativarius
Reply to  griff
August 2, 2021 5:01 am

HI Griffo
Do you know that Isaac Newton was alchemist, and of course he failed. So called climate scientists have succeeded where Newton failed, they transmuted few lines of computer code into many millions of $US, equivalent to thousands of tones of gold.
Griffo, you are wasting your time here, you could be writing some of those code lines. 

Right-Handed Shark
Reply to  griff
August 2, 2021 5:24 am

Of course some climate science is right. It’s just that agenda driven alarmist garbage has usurped real science and is all that is presented to the public.

Richard (the cynical one)
Reply to  griff
August 2, 2021 6:45 am

“Certainly”, griff? Well at least in the consensus of the lemming horde.

Reply to  griff
August 2, 2021 8:04 am

Do you think some climate science could be wrong? I bet you don’t. If you do, give us one example. One example is enough to show you might have a brain.

Reply to  griff
August 3, 2021 9:53 am

The troll attendance award goes to griff.

Ron Long
August 2, 2021 3:41 am

Smectites are hydrous aluminium and silicate layered minerals. The have water in them and can also attract and capture water in their structure. Us geologists test clays by touching the clay to the tip of your tongue, if it sticks it is a smectite type clay structure called hydrophylic, if it does not stick it is hydrophobic. If the Mars smectite hydrophlic clays have microbes on them I would keep my tongue to myself.

Reply to  Ron Long
August 2, 2021 3:52 am

I would bet it will be a rover that will do the test, and it won’t involve a tongue.

Bryan A
Reply to  Rah
August 2, 2021 5:35 am

The first team of Mars Polar Scientists simply needs to publish modeled data claiming a 97% consensus…collude with the “Proper Journals” to prevent the Clay Theory from being discussed and published…Label the opposing Scientists as Pseudo Scientists and Mars Water Deniers…The Clay Theory will dry up

Reply to  Ron Long
August 2, 2021 4:25 am

If Mars hadn’t had liquid water at some point in the past, it wouldn’t have any clay minerals.

James Donald Bailey
Reply to  Ron Long
August 2, 2021 7:34 am

What is the geologist definition of clay?
In normal parlance is a brick or a pottery still clay after it has been dried out?

Reply to  James Donald Bailey
August 2, 2021 10:49 am

Clay minerals are hydrous aluminum phylosilicates. They can only form in the presence of water. They either contain water or hydroxyl molecules in their lattices.

Jim Whelan
Reply to  David Middleton
August 2, 2021 11:34 am

They can only form in the presence of water.

The referenced paper makes no such absolute claim. They always are careful to say “on Earth” and their discussions of conditions on Mars are always, “this suggests” or “this indicates”. Certainly the indication of water is likely true but we cannot make definitive statements about what can or cannot happen in other environments just from Earth condition experiments and observations.

Reply to  Jim Whelan
August 2, 2021 12:05 pm

True… But the Martian clay minerals in Gale Crater did this…

SAM (Sample Analysis at Mars) evolved gas analyses (EGAs; see Materials and Methods) give additional information on the nature of the octahedral sheets of the Murray clay minerals. The temperature of H2O loss during heat-driven dehydroxylation of clay minerals is sensitive to cation content, occupancy, and the position of the vacant octahedral sites in dioctahedral clay minerals (2123). Peak H2O release of the Marimba sample occurred at 610° and 780°C, indicating the presence of both dioctahedral and trioctahedral components, respectively (Fig. 4) (2124). EGA data are inconsistent with the most Fe(III)-rich dioctahedral smectites such as nontronite, which have diagnostic dehydroxylation temperatures of <550°C (2124). Comparison of the dioctahedral-assigned EGA peak at 610°C with laboratory studies of dehydroxylation temperature systematics as a function of Fe content suggests that the dioctahedral smectite likely contains ~5 wt % Fe2O3, requiring that at least half of octahedral sites are occupied by Al (25). The peak water release at 780°C, assigned to Mg-rich trioctahedral smectite, is higher than the 725°C peak observed for YKB samples (24), indicating that trioctahedral smectites in Marimba have a comparatively lower Fe content.

Fig. 4 SAM evolved H2O release of Marimba and Oudam.

August 2, 2021 3:48 am

At least they’re actually doing science! Notice they didn’t make up a modeled Mars polar environment but are doing actual experimentation and don’t express themselves in absolutes.

Reply to  Rah
August 2, 2021 4:06 am

what, like scientists measuring arctic ice and the Greenland ice cap and world temperatures, for decades, are doing?

Reply to  griff
August 2, 2021 4:29 am

I notice you didn’t mention the climate modelers which anyone with a 9th grade level of reading comprehension would have understood were the target of my comment. Wonder why?

Reply to  griff
August 2, 2021 4:50 am

…scientists measuring arctic ice and the Greenland ice cap and world temperatures, for decades, are doing?

And getting wrong. From Wadhams to Gore to Charles the Halfwit of Wales.

What happened to their predictions that the Arctic would be ice free in summer by 2014/15/16 etc It didn’t happen, and looking at current data it isn’t going to happen. But I see where you get your ideas…

Arctic thriller’s film crew struggled to find true frozen waste
Colin Farrell and his co-stars in the BBC’s North Water shocked at the loss of wilderness at the north pole from global heating

Arctic thriller’s film crew struggled to find true frozen waste | Drama | The Guardian

“I wanted us to feel the biting wind, the bitter cold. I wanted to capture that fear that comes from being so far from civilisation.””

Should have gone in winter then.

Bryan A
Reply to  fretslider
August 2, 2021 5:38 am

Dressed in Meat Jackets to count Polar Bears

The Dark Lord
Reply to  griff
August 2, 2021 6:32 am

can you say homonogized ? world temperatures … ha ha …

Bryan A
Reply to  griff
August 2, 2021 10:13 am

Global Temperatures stopped being such when they started expressing temperatures as a factor of energy in Joules rather than deg F/C
If the world doesn’t indicate heating, change to energy balance

August 2, 2021 4:00 am

“Water, water everywhere but not a drop to drink”

Reply to  rbabcock
August 2, 2021 4:26 am

There certainly was “water, water, everywhere” at some point in the past.

Reply to  rbabcock
August 2, 2021 4:42 am

If this ignorant truck driver had to bet, my money would be on underground aquifers well below the surface.

D. J. Hawkins
Reply to  Rah
August 2, 2021 6:01 am

The problem is, just being buried doesn’t keep the water warm enough to be liquid. Earth has a molten core (for now) that pumps heat to the surface. Mars’ core is too cold to support the convection in its mantle that would bring the heat close enough to the surface to melt the ice.

Reply to  D. J. Hawkins
August 2, 2021 8:26 am

At this point I think they would be quite happy to find free water, frozen or not. At one time they thought they had some frozen at the poles. But even if there is some mixed in or covered by the “dry ice”, how accessible will it be how much would it limit human exploration? Even frozen water in subterranean reservoirs offers hope for exploration missions in places other than the poles.

Jim Whelan
Reply to  Rah
August 2, 2021 8:53 am

At this point I think they would be quite happy to find free water, frozen or not

And there is the problem. Scientists who are happy about one discovery but sad about its opposite are prone to bad science. They look for the “happy” result and even slant their observations toward that result. Meanwhile they ignore the possibility of the “sad” one.

All too many “sciences” are following the lead of “climate science” into this pit.

Reply to  Jim Whelan
August 2, 2021 9:48 pm

… and to think that at one time people thought there were canals on Mars!

Peta of Newark
August 2, 2021 4:06 am

Is there much of that stuff laying around? Anywhere?

It would be epic good stuff to plaster around places where ‘forest fires’ abound
It traps water and thus also nutrient.

Use it to help your trees.
Use it to feed and encourage your trees.

Don’t burn them – and then with some of the above TLC, they won’t burn either themselves or you
The Weather will turn out nice too

Reply to  Peta of Newark
August 2, 2021 8:29 am

I really don’t know what to say to someone that believes all wildfires are bad and that does not understand that wildfires are a natural part of the cycle of rejuvenation.

Philip Mulholland
August 2, 2021 4:13 am

“Communities can generate their own little scientific ecosystems,”

“These communities can be self-sustaining,”

Martian polar scientists belong to a small, tight-knit community.

That is why I always try and read the work of mavericks. Not because they are right, but because they can be wrong in a different way.

Last edited 1 year ago by Philip Mulholland
Brian Pratt
Reply to  Philip Mulholland
August 2, 2021 7:58 am

Their assumption that crack systems in laminated lacustrine sediments are from desiccation and desiccation only is an example, Phil.

Daniel S.
August 2, 2021 4:14 am

How do they explain the growth and receding of the “non” ice caps that coincides with solar activity on Mars?

Reply to  Daniel S.
August 2, 2021 9:50 am

Not sure what solar activity you’re referring to; the caps do expand and shrink depending on the Martian seasons (Mars is tilted on its axis in an amount almost the same as Earth). The caps are largely made of frozen CO2. IIRC, the amount of CO2 in the atmosphere inversely tracks the size of the northern polar cap (the southern cap is considerably smaller, and therefore affects the atmosphere less).

August 2, 2021 4:23 am

Where there’s clay, there is (or was) liquid water.

Reply to  David Middleton
August 2, 2021 5:55 am

Perhaps OT, but the other day I visited a ¨neanderthal¨ cave with 100,000 year old floor rimstones with liquid water, even when above the 50m thick cave roof -50C during the ice ages was common. The cave floor stayed at 0C approx all the time – is it possible?
I know Mars’ low density atmosphere precludes this in the current epoch.
Any evidence of rimstones or speleothems awaits a cave rover…

Last edited 1 year ago by bonbon
Reply to  bonbon
August 2, 2021 9:56 am

Most caves on Earth form in limestone, which is soluble in slightly acidic water. Water percolating down through decaying vegetation picks up CO2, making it slightly acidic.

Some caves on Earth are lava tubes, generally formed when lava channels crust over while the molten lava is still flowing. When the source of the lava runs out, if the slope is sufficient then the lava still in the tubes exits at the bottom of the slope, leaving a hollow tube.

A few caves on Earth form in other ways: sulfuric acid passing through limestone or dolomite (due to Sulphur deposits), cracks due to movement of rock, etc.

Mars almost certainly has no limestone. It’s possible there are lava tubes, indeed there is a photo of a probable opening into such a tube; see e.g. (and the cautionary note under the picture).

Reply to  David Middleton
August 2, 2021 12:18 pm

Including carbonate rocks identified by the Curiosity Rover in Gale Crater…

The sample analysis at Mars instrument evolved gas analyzer (SAM-EGA) has detected evolved water, H2, SO2, H2S, NO, CO2, CO, O2, and HCl from two eolian sediments and nine sedimentary rocks from Gale Crater, Mars. These evolved gas detections indicate nitrates, organics, oxychlorine phase, and sulfates are widespread with phyllosilicates and carbonates occurring in select Gale Crater materials. Coevolved CO2 (160 ± 248–2373 ± 820 μgC(CO2)/g) and CO (11 ± 3–320 ± 130 μgC(CO)/g) suggest that organic C is present in Gale Crater materials. Five samples evolved CO2 at temperatures consistent with carbonate (0.32 ± 0.05–0.70 ± 0.1 wt % CO3). Evolved NO amounts to 0.002 ± 0.007–0.06 ± 0.03 wt % NO3. Evolution of O2 suggests that oxychlorine phases (chlorate/perchlorate) (0.05 ± 0.025–1.05 ± 0.44 wt % ClO4) are present, while SO2 evolution indicates the presence of crystalline and/or poorly crystalline Fe and Mg sulfate and possibly sulfide. Evolved H2O (0.9 ± 0.3–2.5 ± 1.6 wt % H2O) is consistent with the presence of adsorbed water, hydrated salts, interlayer/structural water from phyllosilicates, and possible inclusion water in mineral/amorphous phases. Evolved H2 and H2S suggest that reduced phases occur despite the presence of oxidized phases (nitrate, oxychlorine, sulfate, and carbonate). SAM results coupled with CheMin mineralogical and Alpha-Particle X-ray Spectrometer elemental analyses indicate that Gale Crater sedimentary rocks have experienced a complex authigenetic/diagenetic history involving fluids with varying pH, redox, and salt composition. The inferred geochemical conditions were favorable for microbial habitability and if life ever existed, there was likely sufficient organic C to support a small microbial population.

Last edited 1 year ago by David Middleton
John Larson
Reply to  David Middleton
August 2, 2021 1:16 pm

Where there’s clay, there is (or was) liquid water.”

Couldn’t the water have been “imported” via impacts of icy comets and such, rather than be indicative of ancient “bodies” of water having once existed on the planet?

Reply to  John Larson
August 2, 2021 2:54 pm

It could have been “imported.” Earth’s water could also have been “imported.” However it got there, there is extensive geomorphological, stratigraphic and mineralogical evidence for lacustrine and fluvial processed over large areas of Mars around 3 billion years ago.

Jim Whelan
Reply to  David Middleton
August 2, 2021 5:56 pm

3 billion years is a long time. Smaller planets like Mars lose their water because over time the water dissociates and the hydrogen escapes the atmosphere, leaving the oxygen to combine with other elements like iron.

Reply to  Jim Whelan
August 3, 2021 5:58 am

We know that some of the water has been retained in hydrated mineralogy and ice. There does also appear to be ephemeral episodes of flowing hypersaline water at the surface. If there is any liquid water remaining on Mars, it is likely to mostly be in the subsurface and hypersaline.

Jim Whelan
Reply to  David Middleton
August 3, 2021 4:57 pm

I believe that’s my point. I personally doubt that the appearance of “ephemeral episodes of flowing hypersaline water at the surface” is due to water flow any more recently than your stated 3 billion years, and may not be due to water at all.

John Larson
Reply to  David Middleton
August 2, 2021 6:13 pm

Thanks . . but I’ll take that as “yes”, since it’s kinda obvious (to me) that if the Earth’s oceans could have been imported, the relatively piddling amount of water needed to leave some evidence of merely significant amounts having arrived on Mars at various points, without it ever having been a truly liquid water friendly place, leaves me with the impression you’re . . a wee bit on the hopeful side, shall we say ; )

Reply to  John Larson
August 3, 2021 5:59 am

The sedimentary geology on Mars was not the result of “a piddling amount of water.”

Jim Whelan
Reply to  David Middleton
August 3, 2021 5:00 pm

At this time there’s no way of knowing it was due to water at all. Personally I think all the “water on Mars” talk is mostly a “there are canals” type of thinking.

Reply to  Jim Whelan
August 4, 2021 5:42 am

We know that Mars once hosted large bodies of water as well as we know that the Norphlet aeolian sandstone was deposited in an arid desert environment. I don’t need to have lived in the Jurassic Period to know that the Norphlet was deposited as sand dunes. I just need to understand sedimentary geology.

The team’s analyses are based on the same tried-and-true, well-established methods used to infer the geological processes that sculpted Earth’s rocks. “You don’t need magic new science to understand the geology of Mars,” notes Janok Bhattacharya, a sedimentary geologist at McMaster University in Hamilton, Canada.

Since its landing, the Curiosity rover has been gathering data as it makes its way up a long, gentle slope. So far, the rover has climbed across—and thoroughly scrutinized—a 75-meter-thick layer of material that seems to have accumulated under a variety of conditions.

“For the first time, researchers have a reasonably thick section of sediments that provide a long-term picture of what was going on on Mars at the time,” says Kevin Bohacs, a sedimentary geologist at ExxonMobil in Houston, Texas.

The lowest layers of rocks, and therefore the first to accumulate, are chaotically layered sandstones that include pebbles ranging up to 22 millimeters across (slightly larger than a nickel). These bits show various degrees of smoothing—evidence, Grotzinger says, that the rocks were fiercely tumbled by moving water as they hopscotched downhill within the crater. “How [these pebbles] are shaped and how they’re arranged in the sediments are consistent with their origin in the crater walls dozens of kilometers away,” says Douglas Jerolmack, a geophysicist at the University of Pennsylvania.

“Wind simply can’t move the types of sediment that water can,” Bhattacharya says. So, the size and arrangement of materials in these rocks strongly suggest they were deposited by running water.

It’s possible to assess the strength of the flows that carried the material by judging the size and roundedness of the largest pebbles, Grotzinger says. These were not catastrophic floods, he notes, but were ankle-deep to waist-high flows “probably akin to a vigorous canoe ride.”

The rocks immediately overlying the streamflow deposits suggest that over time, waters accumulated in that portion of the crater to form a small lake. That inference comes from the sloping deposits whose layers dip southward, away from the crater wall, at angles between 10° and 20°. These sediments—in geological terms, these clinoform sandstones—haven’t shifted to tilt since they were deposited, says Grotzinger; they actually stacked up on an angle as they formed. On Earth, such deposits develop when sediment-laden waters flow into a lake or other standing body of water.

With a sudden drop in current speed, the flow can no longer carry as much sediment, so that material falls to the lake bottom. As more and more sediment accumulates, the deposit grows, with much of the new material added on the sloping, downstream edge of the deposit. (Similar large slugs of sediment have formed at the upstream end of dam-created reservoirs such as Lake Mead and Lake Powell in the southwestern United States, Grotzinger notes.) It’s not likely that such layering resulted from windblown sediments such as volcanic ash or from the slumping of sand dunes or other loose material, he adds.

Gale Crater has thick layers of mudstone (AKA shale), sandstone and conglomerates. Some of the sandstones clearly appear to be aeolian, others clearly appear to be fluvial deposits. The mudstones are composed of clay minerals that release water when heated.

Jim Whelan
Reply to  David Middleton
August 4, 2021 6:52 pm

All that assumes Mars is like Earth when it isn’t. For example, “Wind simply can’t move the types of sediment that water can,” thatnismfalse. Wind can move just as much material but it does take longer. When water is present it will quickly wash away any wind deposits. If there is no water, wind CAN deposit significant amounts of sand.

The beginning of the article contains a statement: “You don’t need magic new science to understand the geology of Mars,”

I’m not suggesting “MAGIC” or “NEW’ science but I am saying that assuming processes on Mars are identical to those on earth might be a mistake.

Heed the article’s claims:

occasional <b>signs</b> of flowing water on Mars

The findings <b>hint</b> that the Red Planet

And consider that

once had a climate hospitable enough for microbial life to develop and evolve

Is pretty bold since we are still quite unsure about how life evolved on the earth


The team’s analyses are based on the same tried-and-true, well-established methods used to infer the geological processes that sculpted <b>Earth’s</b> rocks.

Is extremely Earth centric.

I am not claiming water couldn’t have existed. I DID say, “Personally I think,” It’s just an opinion based on planetary scientists having a seemingly overwhelming desire to find water and life on Mars. I think they have lost a lot of objectivity on the subject.

Jim Whelan
Reply to  John Larson
August 2, 2021 5:52 pm

All planets form from the accretions and, as they become larger, impacts of other bodies. Some of those are certainly water ice comets, so all water is “imported”. There is no doubt that’s where earth’s water originated.

To me that means water was present and could certainly have combined with silcates to make clay which remained there since Mars’ formation. Just because clay forms on Earth (a water rich planet) from liquid water doesn’t mean that’s the only way they form anywhere else.

August 2, 2021 4:24 am

If you really want to know it seems somebody has to go there just as they did with Apollo.

Are the greens perturbed by interplanetary emissions?

Reply to  fretslider
August 2, 2021 1:00 pm

I was going to say this, too, that until someone actually GOES there and LOOKS at all this ‘evidence’ we will never know. There may, or may NOT, be water on Mars. Also, there may, or may NOT have BEEN water on Mars. But, if that water turns out to be highly polluted with some deadly organic chemicals, what good will it do Humanity? We already have plenty of poisonous waters right here on Earth. Mars, with little, or no, atmosphere (at least for humans) is not a suitable locale for humankind to exist in. We humans are uniquely well adapted to the atmosphere here, on Earth, irregardless of the ‘climate’. There are no other planets in THIS solar system where we can live comfortably, so far, except for artificial conditions. Such as living in a huge dome-like plastic city, and then what happens when meteorites inevitably penetrate that dome? Mars, as noted above, has very little, if any, atmosphere to burn them up before they strike. No Oxygen, either, remember? I have an idea; Let’s send all the liberals there. to setup the base camp?

Captain climate
August 2, 2021 4:26 am

NASA will continue dangling the prospect of liquid water on Mars as long as we pay for missions. If we said we were just studying clay and rocks and not potential past life, no one would care.

Thomas Gasloli
Reply to  Captain climate
August 2, 2021 7:04 am

Exactly. The if it weren’t for the delusional “search for evidence of life on Mars”, “search for evidence of water in Mars”, no one would fund this. You can only get “science” funding by pushing science-fiction.

Same thing with “climate science”; everyone involved knows the ice core data disproved the CO2 causes it theory, but how to get funding for your field without a science-fiction hysteria to get Congress to give you the funds.

In other news the AMA has decided all that stuff about DNA and chromosome is false and wants “sex” removed from birth certificates. Believe the experts? Count me out.

Jim Whelan
Reply to  Thomas Gasloli
August 2, 2021 6:01 pm

Way too much of today’s science is like that, especially when government funding is needed. Look at particle physics and all the hoopla over “god particles” and strings. All the “gee whiz” stuff is needed to get funding for those billion dollar accelerators. But I have to question whether they are really making progress or just “discovering” the things they want to find.

Reply to  Captain climate
August 2, 2021 8:22 am

Well….. The Doomers are thinking the Earth is toast and wishing for a new life on pristine Mars in their pressurized communes away from evil right-wingers/capitalists.

Jim Whelan
Reply to  beng135
August 2, 2021 6:02 pm

They are welcome to Mars if they will just leave the rest of us alone!

Reply to  Captain climate
August 2, 2021 5:44 pm

You’re quite right. This is why they have never repeated the Viking tests that were done almost half a century ago. They’re afraid there will be no signs of life thus no more funding!

Philip Mulholland
August 2, 2021 4:28 am

Reflective clay layers are one of the pitfalls of AVO analysis.

Reply to  Philip Mulholland
August 2, 2021 12:19 pm

Not as bad as marl… I hate marl.

August 2, 2021 4:37 am

Clay without water is just powder, a fine-grained sort of dirt that loves water and soaks it up. Just another form of dirt. When clay powder is mixed with water, it can turn into bowls, cups and plates and cat bowls, and other useful objects like floor tiles and baking dishes.

So if this particular clay (smectite) is storing water from the few frozen spots on Mars, that makes it a useful discovery. Won’t stop the dust storms, though.

Reply to  Sara
August 2, 2021 4:50 am

Clay minerals don’t exist without water.

Reply to  David Middleton
August 2, 2021 12:43 pm

True, and I thought you might enjoy this U of I paper on clay. It’s kind of old, and there are no graphs, but there are some very nice schematics of how minerals are arranged to form clay molecules, and how water fits in there to help those arrangements.

So the hippies will get up there via Elon Musk’s space transport, and immediately set up shop, making pottery of Martian clays (which seemingly are not much different from Earth’s stuff, but it’s from MARS!!!). But has anyone yet done this kind of stuff with lunar dirt? Nah, not nearly exciting enough, even if there’s ice at the Moon’s south pole.

The things I do to make people happy….. 🙂

Last edited 1 year ago by Sara
Reply to  Sara
August 2, 2021 1:09 pm

Oh, one last thing: clay minerals laid down in layers are called ‘varve’ or “varved clay”. I’m under the impression that there is more than just smectite on Mars. Bentonite loves water, too, y’know.

Bruce Cobb
August 2, 2021 4:46 am

“In planetary science, we often are just inching our way closer to the truth,” Plaut said. “The original paper didn’t prove it was water, and these new papers don’t prove it isn’t. But we try to narrow down the possibilities as much as possible in order to reach consensus.”

That’s odd. Are they trying to reach the truth, or consensus? It sounds as if they believe the two things are one and the same. And as for calling veering from one wild, unsupported claim to another “inching our way closer to the truth”, why that is just laughable nonsense.

August 2, 2021 5:07 am

very amazing keep posting good stuff very valuable for me

August 2, 2021 6:02 am

I blame global warming.

Reply to  shrnfr
August 2, 2021 1:05 pm

Why not? Everything else gets blamed on it!

August 2, 2021 6:24 am

Life may be absolutely dependent on water, however water may be in no way a cause of or for life. That is very old science based on cells and the magic within. It completely ignores information technology. Look into it and stop the fairy tales.

The Dark Lord
August 2, 2021 6:30 am

But we try to narrow down the possibilities as much as possible in order to reach consensus.”

gee I thought they were trying to reach the truth not a bunch of similar guesses …

Richard (the cynical one)
August 2, 2021 6:42 am

“We try to narrow down the possibilities as much as possible in order to reach consensus.” A telling phraseology, showing a shift in the mindset of science and research, which used to try to reach the truth, the facts, regardless of the popularity of the conclusion.

Pop Piasa
August 2, 2021 7:50 am

One of the most disturbing things about NASA is their belief in consensus. Good science ignores concentric opinions and seeks to disprove rather than “settle” on the most popular hypothesis.

This is the “science by bureaucracy” that Eisenhower warned would ruin the nation.

Last edited 1 year ago by Pop Piasa
August 2, 2021 7:50 am

There should be vast amounts of salt accumulation from the global ocean that once covered Mars for quite some time in its early past if that global ocean existed for a few hundred million years or more. It may be there is, but has been covered up by a few billions years of wind borne dust deposition. Maybe the same for perpetually frozen ‘lakes’ that froze solid and are now covered by dust and other regolith that got deposited by all the smashing asteroids that would have rearranged some of the Martian surface. We need to take a BF core drill to Mars that can drill a few thousand feet deep. That would tell us a lot instantly about the life history of Mars and where is all the water. My bet is on deep underground saline aquifers, the remnant of the original global ocean on Mars.

Reply to  Earthling2
August 2, 2021 10:02 am

I guess the question would be where the salt in that ocean came from. On Earth it comes from decomposition of rocks by rain water, and from seeps. I think (but I’m not sure) the salt in the seeps comes from salt domes, i.e. from salt in former oceans or seas that dried up. It’s not clear that the same chemical processes would have been common on Mars, given its different climate. Or if there are salts there, what kind–sodium chloride (most common in Earth’s oceans), or other kinds of “salts.”

August 2, 2021 8:31 am

Why is there so much pure speculation in “science” journalism and so little verified new learning?

August 2, 2021 9:26 am

Only one thing to do. Go there and dig.

Reply to  pochas94
August 2, 2021 1:09 pm

And don’t forget to take those thousand foot long drilling pipes with you, too! You are going to need them!

August 3, 2021 9:52 am

Know your smectites before watching the The Martian movie with gale force winds of destruction and other make-a-buck productions and fictional books.

Michael S. Kelly
August 3, 2021 5:30 pm

I think this is conclusive proof that a thriving civilization using nuclear power dwells below the Martian pole, with the waste heat keeping a liquid lake above them, shielding them from prying radar eyes.

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