Vacuum Fossilization - A Unique Martian Process

Because of its low atmospheric pressure, a unique sort of preservation occurs

What makes Mars so different?

   For the most part, Mars is little different from Earth.  It is made of the same materials, it is the same age as Earth, and it shares the same Sun.  Its only differences in the past were its smaller mass and its greater distance from the Sun.  But those differences have led to some rather unique surface conditions.

   To start with, the atmosphere of Mars was lost due to three processes.  First, the lower mass means that its gravitational field is much weaker than ours.  It is much easier for warmer air molecules to escape to space because of this.  Second, its smaller core meant that its volcanic action ran out of power long ago, so its atmosphere and oceans could not be replaced naturally.  Third, aquatic life consumed the carbon dioxide in the atmosphere as they constructed their shells and skeletons.  Calcium carbonate is the result, and much of the Martian atmosphere is literally lying on the ground or blowing like dust in its winds.

   So now we can see how as the atmospheric pressure dropped, the boiling point of water also dropped.  Eventually, probably about 400 million years ago, its air was so thin that the existing temperatures could easily boil water that might be heated slightly above the ambient temperature.

   For the most part, this is not much of a problem.  As the air got thinner, the greenhouse effect that it supported also slacked off, and the Martian surface cooled off.  This was good for its oceans, as that slowed evaporation and kept the water in place.  But anything venturing out of the water might have been unable to return quickly enough to stay alive.

How does lower air pressure change things?

   Because of this lower pressure, a new sort of fossilization can occur.  Imagine that you were to drop a piece of meat in the desert sun.  In a few hours, it would probably have dried into jerky.  This is a process of natural mummification.  Now, imagine that there is very little rainfall, and that there is also almost no air.  What would happen?

   Not only would the meat dry out much more rapidly, but if it were protected from the raw sunlight by a layer of mud or dust, it might be able to remain in that desiccated state for very long periods of time.  On Mars, this is exactly how many of the fossils were formed.

   Terrestrial fossils typically are formed when an organism is covered by silt or soil and there is very little oxygen to promote decomposition.  The organism becomes covered by a growing layer of silt or clay, which compacts and isolates the organism.  Eventually, if nothing disturbs or consumes the dead organism, water that carries dissolved minerals can seep into the tissue and replace the organic molecules with inorganic ones.

   Over an extended period of time, all that might be left is a print in a rock, or in some cases, a stone replacement of the original organism.  There are cases where the details are preserved right down to the cellular level if the conditions are just right.  But this is a process that requires liquid water and often weak carbonic acid dissolved in the water.  Carbon dioxide in the atmosphere can form carbonic acid, which takes silica or carbonates or other minerals into solution.  This is what replaces the organisms tissues.

   On Mars, this process probably happens also, but the low air pressure brings about a whole new process that is more like freeze-drying than true fossilization.  Imagine that a meteor impact occurs in a shallow pool full of marine organisms.  They are splattered out of the pool and may land on the surface.  A mixture of mud, salt water, and stunned organisms is then layered on rocks or soil, where there is a near vacuum.

   Since the water is probably heated from the impact, it is more likely to boil away quickly.  Also, the layer of mud will stick over the organisms in many cases, sheathing them and protecting them from the direct sunlight.  As the heated water vacuum boils away, the organisms die and are stuck in place for millions of years, and even if a thin rainfall did occur, it is likely that the water will evaporate quickly.

So what?  How does this explain anything?

   This explains how many soft-bodied organisms such as squid can be so perfectly preserved.  It also explains one of the most fiercely debated points- how "igneous" rocks can have fossils on them, when it clearly and logically requires sedimentary processes to make fossil beds.  Here are two perfectly workable (and testable) methods of vacuum fossilization.

   One- the impact scenario outlined above occurs, leaving a coating of mud and organisms on an igneous rock.  The vacuum freezes and dries out the organisms in the protective coating of mud, to be preserved for exceedingly long periods of time.  Wind and sandstorms can eventually wear them away, leaving "sliced open" organisms with a great deal of detail that soft bodied fossils usually will not leave.

    This is a known viable mechanism since the Meridiani Planum area has many small and medium sized impact craters.  And, many fossils have been found on rocks and outcrops in exactly the sort of situation that an impact would have produced.

   Two- a tidal pool or lake suddenly drains out, perhaps by an impact breaking open a natural dam or retaining wall.  This has been documented on Earth, where ground movement suddenly drains thousands of acres (or floods them) and changes the landscape dramatically in a matter of minutes.  On Mars, there is little or no ground movement so meteor impacts and dust storms are probably the two most powerful weathering forces on the planet, and an impact could drain a crater lake in minutes.  Craters are common on Mars, and from the evidence many are billions of years old.  And, Gusev Crater was once a lake, so imagine it filled with water, and a meteor impact breaking the crater wall and spilling out billions of liters of water in the space of minutes.

   This sudden drainage concept perfectly explains the billions of fossil urchins, cystoids, and trilobites scattered uniformly all over Meridiani Planum.  It was a shallow sea, and I hypothesize that it was drained suddenly, leaving all the organisms on the surface to dry out over the course of a day in near vacuum and raw sunlight.

    There is another simple explanation that is nearly identical to this idea.  Sinkholes can drain a lake in minutes to days, depending on the size and the capacity of an underground cavern or river.  If a sinkhole or a number of sinkholes opened up in Meridiani Planum, the water could have drained over the course of a few days, and the result would be that little or no "washing out" would occur to disturb the organisms.  Everything would remain in place.

    To support this idea, we observe that Meridiani Planum is indeed dotted with numerous sinkhole-like structures, and that they tend to line up along what might be underground channels.  Here is a story about a lake vanishing in days recently on Earth.  Lake Chesterfield, in Missouri, disappeared in less than a week.  23 acres drained away, leaving fish dead everywhere and no trace of the water.

    If this had happened on Mars, then the organisms would have been left laying all over to dry out and "fossilize" in the vacuum, precisely as we see on Meridiani Planum.

   If you think about it, trilobites on Earth use calcium carbonate as the lenses of their eyes, and the Martian equivalents probably used it in their skeletons.  Sea urchins and sand dollars certainly do, and this means that if you were to freeze dry one and then sand blast it with fine dust for millions of years, it would look exactly like the fossils we see there today- called "blueberries".  Calcium carbonate can easily pick up iron oxides and end up colored blue, as any fossil hunter who has old seashells can tell you.

Is there any evidence of this "vacuum fossilization" process?

   I have found numerous examples of substrates that appear to be dried mud, rather than some more basic rock.  In some cases, I have found that the edges or portions of the mud is broken away.  Examination of those edges shows that it appear to be riddled with millions of tiny bubbles, exactly as vacuum-dried mud would be expected to have.

Here is a shot of dried mud from Opportunity, Sol 030.  The original data is here at the NASA website.   You will see that it looks precisely like dried mud on Earth.    This is a bed of dried leaves, most probably of an aquatic plant like kelp.  It has been deposited along with a coating of mud on the notorious "fossil bed".  You can see that the texture of the mud is conformal and smooth.  Each independent leaf-shape can be made out as overlapping and covering other leaves.    Some even show the thin, rippled edges of almost any leaf.  The foremost edges of some are worn down, presumably by dust and wind.
This shows the serrated edge of a leaf.   It also shows the overlap of another leaf upon it.  Each and every piece of this is wafer thin and layered upon other wafer thin pieces.  Each is coated with a layer of smooth, rounded mud.    You can see how flat and conformal each leaf in the pattern is.  You can also see the rounded shape of the mud coating them.    The red arrows show some of the places where one leaf overlaps another.  The red wavy line mimics the outline of one edge of a leaf.    Is there any serious doubt that these thin layers are leaves?  No mineral structure creates this pattern.  Mica can form thin layers, but these are all roughly the same size, have pointed outlines, and wavy edges.  Some impact event splattered these leaves and a coating of mud on this outcrop of rock, where it vacuum dried and left these fossil leaves behind.

   This picture is a cross-eyed stereo view of the fossilized leaves.  You can see just how these shapes are flattened against each other and how they are coated in mud that has dried and been polished by very fine dust in the Martian winds.  Next is a magnified and much clearer example of vacuum drying.

In this image, I have outlined many pockmarks that in my opinion represent the solidified bubbles that were created by outgassing.    As the mud dried in the vacuum, a large number of bubbles formed and some popped, leaving these pockmarks.    With lower gravitation, surface tension and other fluid processes would have a greater influence on the texture and surface of the mud than they might on Earth.

    So, if this really is just dried mud, it should crumble very easily if we try to cut or abrade it, right?

NEXT