HYPOGENIC CAVES IN PROVENCE: BIGOT

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DID YOU SEE THE GOOGFLE ADSENSE ADS ON THE RIGHT?

1) BACTORGS HAVE TO LIVE SOMEWHERE
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In the last post, you learned about the hypogenic caves of Movile and Villa Luz which are home to enormous biofilms containing hundreds of species of exotic bacteria eating rocks and producing sulphuric acid. These caves contain also "out of this world" ecosystems feeding on these bacteria. With their spiders, worms, scorpions and many other, they form a nice set up for my bactorgs.

Now the next question is:
This post tells you all about the reasons underlying that choice.

2) PROVENCE, THE IDEAL LOCATION FOR "WE SHARE"
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My novel will describe events taking place in the part of Provence named "Alps of high Provence", near the towns of Apt and Forcalquier, a transition area between the provençal plain near Marseilles-Aix and the high Alps of the Mont Blanc.

I want to locate the novel there for personal reasons because this is my favorite area in the world, the one I know best, the one in which I have been caving for the last thirty years, the one in which people are so kind to me.

I want my reader to experience its lavender fields, its hills lined with mountain oaks, its quiet, three hundreds years old, small villages perched on top of the hills, its springs and fountains, its serene way of life, the warmth of the day and the coolness of the night when the crickets sing their song. Let's also not forget the cold "rosé" wine, the goat cheese and the olives...

2.1 A few photos of the Apt area

Just to introduce you to the area, you will find hereafter a few photos. To see more, do a Google image search on keywords like "Banon, Oppedette, Forcalquier, Montagne de Lure, Mont Ventoux, Dignes, Gap, Sisteron". Try a Google Earth 3D view. You'll be rewarded by peace, beauty and pleasure.

First a general map: on the map, the area we are discovering is centered in one square centimeter around the town of Apt.Let's see now a view of the nature there. For France, it is a quite unpopulated area but not a wild one,by far. It is a peaceful union of man and nature. You can see a lavender field on the left side, wheat fields, hills, oak forests where boars and deers are roaming. Human life is hard, simple and still far from the unbearable pressures of the consumption society (but perhaps, not for long anymore).

It is time to go underground. Let's do some caving. In this area, we know about two hundred caves, ten of them going to depths of about minus 600 to 700 meters. Local cavers discover new caves and kilometers of passages every year. These are predominantly vertical caves with series of huge pits (the longer one being more than 150 meters deep). Hereafter a photo I took of my son going down one of these pits. It was taken in the Aven ( cave in provençal) of Jean Bernard near Apt and Sault in the summer of 1995. It gives you a feel for what is caving there.

Now, what about "surface life"?

Here is an old village called Saignon, five milles from Apt (look at the map again). it was built in 1500 on top of a hill to protect its inhabitants from the religious wars of that time.

And a close view of the lavender field which you saw above in the general picture.

You can't feel them of course but when I see this picture, I experience the smell, the tiredness of the day spent in the caves, the excitement to get there, the hot sun, the sound of the crickets, the burning hope for a glass of white or rosé whine in the nearest village, I tell you... this is, life at its best!

Now, a medieval passage in a nearby town (Sisteron). By the way such a passage, between houses and covered by stones, is called an "Androne" in Provençal. Does it ring a bell (anything in common with my neuronal cultures)?
From the above pictures, you might get the feeling that life is tough and austere in these high lands,... far from it. Here are a few proofs: goat cheese (the locally famous Banon), wine (the world famous Luberon wines), fruits and little terraces where, in quiet evenings, you can just enjoy life at its best.

2.2 The Apt area, more than just a nice place

Its nice to locate my plot there but I told you before that I wanted my novel to be realistic, I want not only my science to be as exact as possible but also other aspects like geography, ecology, human life and economy. If I want the reader to discover and enjoy the true Provence, I cannot invent an artificial one well suited to my purposes. I have to make my plot to fit naturally in the real Provence.This is a tough order; it means that in an area of about one hundred square kilometers, I must have several very specific features:

° First, I need an area suitable for quite advanced caving.

From what I have told you, you already know that the Apt area fits the bill but let me give some more details.

Look at a map of Southern France. Near Avignon, between Forcalquier, the Montagne de Lure, the valley of the Jabron, the Ventoux mountain, and the towns of Sault and Apt lies an area called the "Pays de Giono" or in English, the "country of Giono" (Giono is one of the main French writers who placed almost all his novels in this area). It is a country of rude living , big skies and green hills. People are friendly but reserved and cautious. Their life has many joys but little comfort.

The city of Apt lies just at the border of the "Pays de Giono". The caving part of the "pays de Giono" has the geologic structure illustrated below. There is a limestone layer (see "massif calcaire karstifié" in the figure). It is 600 to 1000 meters deep. Through it, run many predominantly vertical caves (the black jagged lines). Under this limestone layer, there is a layer of molasse and marne in which water cannot penetrate.

The water from all the caves is thus collected naturally into a series of collector, underground rivers. You can see one of them in the figure. They flow at the boundary between the limestone and marne layers. Cavers have been able to penetrate many of these caves and they have reached a few collector rivers at depth from -600m to -700m. The names of the most impressive caves are the Caladaïre, Jean Nouveau, Autran, Le Souffleur d'Albion.

As you can see, on the right side of the figure, the layer of molasses forces the water to come up and in fact, all the rivers join in a single vertical resurgence which comes out at only one point, the world famous “Fontaine de Vaucluse”, made unforgettable by Petrarque's poems and one of the biggest perennial springs in the world. Many divers (human and robotic) have tried, (currently without success) to reach the bottom of the Fontaine hoping to visit the deepest horizontal parts.

In addition to these caves which have a normal speleogenesis from surface water, the area contains also several sulfur and geothermal springs and, probably, a few fossil hypogenic caves (in what is known as the gorges d’Oppedette (the Oppedette canyon) near the city of Apt and nearby in the cave of Daluy).

Note: a fossil hypogenic cave is a cave of hypogenic origin which, during its evolution has been traversed by an exogenic cave (carved by surface waters). After eons of isolation, the hypogenic cave has thus came in communication with the atmosphere. Oxygen has completely destroyed its hypogenic ecosystem but fossil remains of the wall carving by bacteria and sulphuric acid can still be seen. It is what we have in Provence.

Extrapolations for WE SHARE

Thus the Apt area has all I need to suppose that unknown to everybody, a truly hypogenic cave is developing somewhere in the limestone, at a depth of about -600 meters below the surface, traversed only by a small flow coming from the surface and another one coming from the volcanic depths. The small surface flow allowed some invertebrates and insects to crawl in the cave and a Movile-like ecology developed a million year ago. Its bacterial communities are at least a million year old. During that time, they evolved and became Bactorgs (see previous posts)

I will also suppose that contacts were established by the bactorgs with larger insects and mammals which swam or crawled through some side exits of the flow. Bactorgs will be able to influence the behavior of these larger animals and domesticate some of them. Finally, through the domestication of these insects and rodents, bactorgs will be able to control the release of viruses and well choosen bacteria for which their slaves act as reservoirs.

When the story begins, an earthquake has widened the cracks between the hypogenic cave and a normal cave. The Bactorg ecology is perturbed and the hypogenic ecosystem defends itself by launching bacterial and virus attacks on the outside world. Much of the events described in the beginning of the thriller are just due to this defense reaction. Of course humans will react and organize a caving expedition into the Bactorg domain.

° This, I need a caving area which can plausibly harbor an active hypogenic cave.

This is not a small point: after all, we know only about ten of them in the world. For weeks, I did not dare to check on that point but finally I did it. A Google search on "hypogenic caves and Provence" got me absolutely flabbergasted. Here they were...! Just where I needed them. Of course, they were not active or alive like Movile, I would have known about them. They were hidden, fossil caves; hypogenic bubbles in the karst opened to the surface many thousand years ago but still showing remains of their hypogenic stages. To read a paper in English about hypogenic caves in Provence, click here (paper by Audra, Bigot and Mocochain in "Speleogenesis and evolution of karst aquifers")

For the last twenty years, my absolutely favourite village in the world has been Oppedette. It has only fifty inhabitants and the nearest town, Apt, is half an hour away. For a densely populated country like France it is quite isolated. For twenty years, I have each year spent months in Oppedette, living, sharing and speaking with the village people. Three hundred meters from the village there is a nice gorge, not like the Verdon or the Grand Canyon of course but still..., very impressive and at a more human scale (200 meters deep, six kilometers long). I have spent hundredths of hours exploring it and abseiling down all its rocks and cliffs. Will I tell you one day about Max Fayet, a retired flutist and now the greatest expert on the Oppedette's gorges. At 80, Max is walking everyday more than seven miles in its nooks and crannies to rescue lost hikers?

Here is a view of the village (about thirty houses) at the entrance of the gorges. Sure, it is not the Verdon or the Grand Canyon, but try to go down and visit every part to find hidden caves and passages. It took me many months..

The village:

The gorge: it starts just thirty meters after the village and runs like that for five millesThere, smack in the middle of the gorges, it exists a natural excavation called the "Chaire à Prêcher"). Jean Yves Bigot, a local geologist, studied it closely and found many traces of hypogenesis. Right where I wanted them to be.

He published his findings on the web (click here to see a map of hydrothermal caves in France). I got in touch with him and he told me that sulfur springs were quite common in the area. He told me also that some geothermal springs were not far apart (in a village called Greoux)... The Area near Oppedette had thus everything I wanted. A few post before, I gave you the address of a site he has developed on hypogenic caves. Here is another one, be sure to look at it (Daluis, grotte du chat).

° One more thing and not a small one: For the novel, I need a large underground laboratory...

At some stage, my bactorgs (underground Movile-like bacterial biofilms) will have to meet andrones (real in vivo cultured neuronal networks) living in a high security laboratory. These two guys do thus live far apart. A plausible way for them to meet is in a large, underground laboratory, nearby thehypogenic cave, five hundred meters deep and where scientists are conducting almost secret experiments on andrones and on many other subjects (geomagnetism, zero magnetic field biology...).

You will not believe me but such a lab exists: five milles miles down the road from Oppedette. It is called the "Laboratoire souterrain à bas bruit", or in English, the "Low noise underground laboratory". Years ago, the French army had its main launching site for nuclear missiles right near Oppedette. They had something like thirty underground silos with a missile in each. All the silos were linked to an underground command post, at seven hundred meters below the surface of the hills, wiht kilometers of passages in which electric trains linked the many command and logistic rooms.

When the French dismantled their nuclear force, the underground headquarter was taken over by the CNRS (French center for Scientific research) and transformed into a large underground laboratory which provides one of the most noise free environment all over the earth (no vibrations, no sound, no electromagnetic perturbations). It is where my andrones will live and be infected by the bactorgs messengers living just outside in the caves.

Do a Google search on "LSBB "laboratoire souterrain à bas bruit - Rustrel"(click here to visit the site of the lab). Here are a couple of images from the site of the primary school at Rustrel who, astonishingly went in to visit... (see their site by clicking here)

First a photo of the entrance of the lab; from there a two miles long passage goes deep into the mountain. The deepest part is seven hundred meters below the top of the mountain. In the vicinity, there are no industries, no towns, no large roads, no electronic installations. Almost no noise of every kind. Hence the name.Now, a photo of the main gallery going down to the labs. You can see the small electric train transporting the researchers.

A third picture: down the gallery shown above, the train lead to several rooms isolated from the outside by an armored door, a concrete wall two meters thick and a wall of steel several centimeters thick. Remember, they were part of the command and control post for the nuclear force, built to stand a nuclear bomb. Now they are laboratories in which you are almost vibration, noise and radiation free and ... secret work can be done there. Here is where my andrones will live. Cross the wall of the lab and you have limestone cracks communicating directly with the caves of the area, the ones in which bactorgs live...Two more pictures from a not so distant past... the nuclear cold war. The missiles were placed underground also but near the surface and all around the control center within about a ten miles radius. Each missile was in a silo and the nuclear heads were regularly transported from silos to silos on specially built roads. Everybody could see them. Goats were just liking it.

First the top of a missile silo a bit scary isn' it. No problem, these silos have all been destroyed in 1999.

Then a picture showing a nuclear head lowered down in a silo where the missile is already awaiting for it. Can you believe that such photos can be found on the web?

And finally, the one I find really nightmarish, a nuclear head transported on an army truck going openly on a public road, between the lavender fields. You could see it and hear your heart missed a beat or two. This leads us far from goat cheese and Rosé wine.

° One more thing I need: a trigger event for a bactorg-driven epidemic.

First and foremost, I need an earthquake. Fine: Provence is one of the most seismic areas of France. They don't have big quakes but lot of small ones. That's OK for me. I prefer small ones. They go unnoticed by humans but may cause large changes in the underground. They will open new cracks and perturb the bactorgs without humans noticing it. A large quake would not fit my bill.

Here is the distribution of small seismic events in Provence (Richter scale below 4.5) over the last twenty years. The region we are interested in is below Sisteron (see the blue oval).

One consequence of the earthquake will be the opening of a crack between a normal cave and the hypogenic cave which, for a million year, has adjusted to a strong level of isolation. Oxygen will flood in. The atmosphere and equilibrium of the bactorgs will be changed.. They will feel attacked and thay will have to react.

Another consequence of the quake will be the availability of a new food source to the bactorgs. The earthquake will open another crack through which methane and CO2 will flow in enormous quantities. There will be an exponential growth of some parts of the bactorgs (methane and CO2 eaters). Again perturbation and reaction! Bactorgs will start a war upon the outside world to defend their peace and serenity. They will send many kinds of viruses and harmful bacteria, strange epidemics will develop. Who can blame them?

How can this enormous food income take place? A man made catastrophe obviously!

You will not believe me but it's all there. Sadly enough, Oppedette has all the potential I need for a first class drama. Look again at the pictures I showed you before: peace, serenity, calm and joy... Wrong, totally wrong: you already know that nuclear missiles were there... a recipe for catastrophe. Imagine an underground radioactive leak, thirty years ago, initiating a mutation wave in the bactorgs? Why not? Two such leaks occurred just last week in France (July 2008, Tricastin and Roman, not far from Provence).

More plausibly..., I have spoken with the people in the area and I asked them to show me where sulfurous springs existed. I put them on the map. They were delineating several paths. One of them led me to a village I loved, Saint Maime , where my mother in law lives and where I have spent my holidays for the last thirty years. What was this path pointing at. ... To a catastrophe waiting to happen. Here is a photo showing it.The main picture show an area not far from Oppedette, about ten miles down the road in the direction of Manosque. It is a nice valley in the Luberon and it shows very much the same scenery than those you saw before. But it is disrupted by large clearings. What are they? Not wheat or lavander fields but the outside signs of an important industrial underground activity.

This is a picture of the exploitation site of a company called GEOMETHANE. Twenty years ago, it was called GEOSEL. (SEL = SALT in French). They were injecting water in large, natural underground chambers filled wit salt. The water was dissolving the salt. Then the water was ejected under pressure and was transporting the salt outside. Obviously, after a while, the pockets of salt emptied. GEOSEL found a new use for the remaining large cavities: gas storage. Today, they store methane and they could store CO2 if needed. They just had to rename themselves from GEOSEL to GEOMETHANE.

Obviously it created a big stir in the nearby villages. Not everybody was happy to sit on millions of cubic meters of explosive methane transported from and to Marseilles by a pipe line. Obviously, there are strong security requirements but still, here is a catastrophe waiting to happen (what we, in Europe, call a SEVESO site, click here for informations about SEVESO sites).

Of course; For WE SHARE, I do not need an explosion destroying fifty square kilometers and seven villages. In my novel, I want to be much more subtle, at least in the initial phases of the catastrophe. I'll just imagine an earthquake opening a communication between these methane stores and the bactorgs cave near Rustrel along the line of sulfurous springs I have delineated. An enormous food intake for the bacteria, their explosive growth, their reactions...

The details of one of the storage pits are shown in the inset. In fact, they are much deeper than you might think and are located at depths from 90 to 1300 meters deep, just the right depths for my purposes. To give you the sheer size of the possible catastrophe, let me give you a few numbers taken from the GEOMETHANE site. Am I reading them correctly...300 M Ncubic meters. What the hell is this?
What can be the consequences of such an input of methane on the bactorgs... That's for you to ponder. Let me give you a nice little sentence from their official site...,

"These installations are located in sensitive areas of the "Parc Naturel Régional du Lubéron" and received special attention as regards environmental protection, in close co-operation with the Parc authorities and the local communities. " Nice to know

I might be wrong but to me, it is just a typical piece of marketing nonsense and human hubris. Look their site at GEOSTOCK GROUP.

So the area I love best in the world has all I need for my novel, the best and the worst!

° a geology suitable for hypogenic caves,
° an underground lab,
° earthquakes,
° industrial storage of bacterial food.

° And a final fact: I am not that original, in my plot, like in everyone these days, I need the military (however, I think I found a fresh angle on them). And I have to confess I like some of them, I myself spent five years working with the Belgian army where I had a lot of contact with the French Foreign Legion. I want a Legion battalion in the plot because they are partly belonging to the establishment (which I do not like very much) and partly independent of it (in many aspects of their professional life, they establish and follow their own rules).

In "WE SHARE", the legion will have a security department, in charge of supervising scientific battles against terrorism. They will then be charged by the authorities to conduct the struggle against the epidemics but will make many mistakes and learn from them. They will then cooperate with the civilian scientists who will explore the hypogenic cave.

Obviously, you already know what I am going to tell you. At about six miles from Oppedette, there is a big legion camp with an engineering battalion and a small NSA-like listening center. It is the 2nd Regiment Etranger du Génie (quartier Marechal Koenig). Its people are experts on mountain combat (and thus I may suppose that they are knowledgeable about caving). Close to the quartier Koenig, there is really a site brimming with antennas. They won't tell me what it is but I suppose it is their listening center. This is what I will suppose. I will have a bioterrorist study group residing in the Legion camp. They will be in charge of tackling the "WE SHAR outbreak. Here is the site of the Second Régiment Etranger de Génie

Hereafter, a photo of a legion platoon marching near the entrance of the Koenig camp in St Christol, right in the middle of the plateau d'Albion, eight miles from Oppedette. The security site brimming with antennas is about five hundred meters behind the camp. You can see two antennas on the right.

Bye Bye now, I am a bit tired.. This post is a bit on the longish side, it took me a whole day to write it but I just couldn't stop... There were so many things I wanted to tell you about this place.

By the way, I feel a bit guilty to bring catastrophes, even imaginary ones, to the Pays de Giono. I hope my novel will also convey its peacefulness and soft but wild beauty.

Jack

AN HYPOGENIC CAVE: MOVILE

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DID YOU SEE THE GOOGLE ADSENSE ADS ON THE RIGHT?

1) MORE ON HYPOGENIC CAVES
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In the preceding post, I introduced you to hypogenic caves and we discussed Villa Luz, a cave with mixed hypogenic and surface features. Here we will look at a much more hypogenic cave which developed an ecosystem almost completely preserved from outside influence for about 500 millions years. The hypogenic cave I'll invent in "WE SHARE" will be a mix of Movile and Villa Luz but at a much deeper level (minus 600 meters) compatible with the geology of the area where I locate it and with my taste for vertical caving adventures..

2) MOVILE: AN ALMOST OXYGEN FREE ECOSYSTEM
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The Movile cave is situated in Romania near the Black Sea. Its formation and isolation from the external world were made possible by the local geologic features (I believe its limestone layer is somewhat embedded in a clay layer with a very peculiar phreatic level but I lack details on this).

Movile is an active hypogenic cave, carved by sulphuric acid like Villa Luz. However, opposed to Villa Luz, it has been almost totally isolated from the surface since at least half a million years. The processes of rock carving by bacteria and establishment of an isolated ecosystem are thus much purer than in Villa Luz where surface and hypogenic features interfere strongly.

Movile is host to an endemic invertebrate fauna which is probably quite unique (it should be carefully compared to the one in Villa Luz but I do not know of any such comparison). It has adapted, like Villa Luz but much more completely, to the lack of light and oxygen and feeds on the bacteria which themselves feed on minerals dissolved in the water.

The Movile ecosystem is thus autarcic, without any input of solar energy (compare withVilla Luz). The Movilians use only chemical autotrophy (synthesis of organic molecules from inert minerals).

Here you see a vertical section of the Movile cave (sorry, it is in French but easily understandable: grotte = cave, cloche = bell, lac= lake, niveau de la mer = sea level)

You see a vertical entrance pit made by the people who found the cave and closed by doors isolating the cave from the outside atmosphere. (Movile was initially found by a geologic survey team digging there just by chance). When going down that pit, you first enter an upper level of dry galleries. A second short pit opens on a second set of rooms, filled with water at sea level and forming a sequence of gas filled bells and ponds (see the levels of oxygen, methane, nitrogen and H2s indicated in the figure).

It is where we encounter the Movile life (see the interrupted line indicating the biofilm or bacterial veil floating on the water). At the bottom of this level (see on the left) , deep water is entering the cave through a vertical water filled pit where water rich in H2S is coming from deep down (as I understand, it is a sort of geothermal spring ?).

Look now at the bells. In their water, bacteria oxidize H2S brought in by the geothermal springs and which is thus abundant in both the water and the atmosphere of the bells. Bacteria use this energy to synthesize their organic molecules from the CO2 which is also present in the cave. This is described in the following figure (sorry but right now, it is still in French, question: where does the CO2 come from):These autotrophic (i.e. rock eating) bacteria serve as food source for other bacteria and fungi organized in filaments and floating in the water. They are heterotroph (they can only eat organic matter and thus they eat lower, autotroph, living beings, i.e. the bacteria). These filamentous bacteria form biofilms (filamentous, slimy veils floating on the surface of the little ponds) and serve as food for small herbivores.

On top of the bacterial veil, terrestrial herbivores (e.g. isopods, collemboles, pseudo-scorpions) live and graze They are themselves eaten by carnivorous species (e.g. spiders, centipedes…). Below the bacterial veil, worms, crustaceans and snails graze also on the bacterial veil and are preys for leeches and other animals. All these animals were trapped half a million years ago and have adapted to their conditions. They display regressive evolution which suppressed their eyes and color pigments. Moreover, they survive without oxygen. Hereafter you see a few of them

A Movile eyeless spider

A Movile eyeless scorpioThe Movile ecosystem contains 36 terrestrial insect species. Twenty six of them are totally new to science. The density of insects is unbelievable. For instance, more than 1500 collemboles were numbered per square meter of bacterial veil and numerous spiders were observed ( the spiders are known as "Alisco Cristiani"). They have lost their eyes in regressive evolution. This spider species gives us an important clue: his nearest relatives live in the Canary islands. This points toward a specific point: except for bacteria, the Movile fauna seems to originate at a time when Europe’s climate was tropical. These eons of isolation have caused a lot of regressive evolution.

I cannot resist, I have to give you another picture of the eyeless Movile spider, beautiful and frightening, crawling on a gypsum crystal near the bacterial veil:

The aquatic species of Movile are less "out of this worldish". They live in the first ten centimeters under the surface. At this small depth, there is still sufficient oxygen diffusing from the small oxygen content in the air bell. These species had thus to adapt less than the terrestrial ones who were choking in H2S and living in the dark. About 25% of them are new (compare with the terrestrial species where this ratio is about 75%). This suggest that in the past, it was more difficult to crawl in the cave through narrow crevasses than to swim in it through the sumps which, then, linked the cave and the nearby sea or lakes.

According to geologists, the underground network of the Movile bells was created five millions year ago when the black sea emptied itself into the Mediterranean sea. Water and gases from the magma would then have invaded the original cavities and started to carve it more and more. Even today, it exists in the area some sulphurous lakes and swamps with water much like the one of Movile (e.g. lake Kara Oban).

3) Extrapolation: the Bactorg cave
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Hereafter, a rough picture of the cave I envision for my bactorgs to live in. An hypogenic cave has been fed for millions of years by water from a deep water rise. It was almost isolated from the surface. At the surface level, another cave was carved by surface waters but was not connected to the hypogenic cave except fror a small unknown connecting flow at a depth of minus 600 meters. When the novel starts, the passage between the hypogenic and the surface cave has just been opened by a minor earthquake. This perturbates the ecosystem of the bactorgs in the hypogenic cave and triggers all the events described in the novel.

End of this post, time to sleep, Don't dream about eyeless spiders crawling in the dark.

AN HYPOGENIC CAVE: VILLA LUZ

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DID YOU SEE THE GOOGLE ADSENSE ADS ON THE RIGHT?

1) WHY DO WE DISCUSS HYPOGENIC CAVES

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Two posts ago, we discussed bacteria in caves and I promised you more about them. Here it is.

In the last twenty years, cavers have discovered a few caves formed not by surface waters like the one we usually know but by gases and waters seeping from the deep volcanic parts of the earth crust. Often, these caves do not have any communication with the outside world, a fact which explain why we have not discovered them earlier. They are called "hypogenic caves".

The true wonder is that these caves are full of life, archaic life originating in long past geologic times when our atmosphere was not choked with oxygen. They are exactly what I need for my bactorgs.

In this post I will tell you more about two of them: Cueva de Villa Luz in Mexico ( an intermediate cave just at the border between hypogenic and normal caves) and Movile Cave ( a true hypogenic one) in Romania.

If you want to read a report on a fossilized hypogenic cave, do a Google search on "Grotte du chat, Daluis (in French)". Look also the sites devoted to Frasassi cave (Italy). Finally, look also at the many sites devoted to Lechuguilla cave, one of the most beautiful cave known to man. For Lechuguilla, I give you just the site of a short report on a trip in Lechuguilla by Michael Ray Taylor, a caver , professor, journalist and writer specializing in cave bacteria, if you are interested, you should read his book "Dark Life: Martian Nanobacteria, Rock-Eating Cave Bugs, and Other Extreme Organisms of Inner Earth and Outer Space (Scribner, 1999)". Please... do a search on Lechuguilla and on all the caves I have been mentioning... wonders are awaiting you, just a few clicks away.

2. CAVE LIVING BACTERIA AND CREEPY CRAWLIES
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We will discuss two caves in which our bacteria are living; Villa Luz and Movile. The home of bactorgs in WE SHARE is inspired from them but needs a lot of modification to exist in Provence (different climate and geology) and fit my purpose (development of an eon-traversing bacterial community, communications with the outside).

2.1 CUEVA DE VILLA LUZ (TABASCO, MEXICO)

A transition between hypogenic and normal caves

Choking with sulfur oxide (H2S and CO2), having all its galleries coated with strongly acidic slime, a cave in south eastern Mexico is nevertheless teeming with life. Without any solar energy, any light or green plants, an alien food web has evolved in the Cueva de Villa Luz. An ideal set up for my bactorgs. Let's learn about this amazing ecosystem.

You see here a map of the cave.

(Image courtesy of Louise Hose). This map is taken from the following paper:

As you can see, it is not really a pure hypogenic cave (i.e. one having no communication with the outside, far from it. Instead, it has lost of outside communications: the resurgence and all the side entrance pits through which light, heat, gases and all sorts of animals may enter the cave. I see Villa Luz as an intermediate case; a transition between almost hypogenic in its farthest recesses and a normal cave near the resurgence. This is neat... In my novel, I need a way for a truly hypogenic bacterial community to communicate with the surface. Something like Villa Luz might fill the bill. Of course, I will have yet to invent a nice little twist to have it at a depth of about -600 meters.

Note: Villa Luz is a tropical cave warm and filled with life. My novel takes place in Provence... I will have to adjust for this... Provencal caves ar e almost alpinecaves. Life does not fill them.

Anyway, as a transition cave, Villa Luz has a lot to teach us about hypogenic ecosystems. Let's discover it.

THE VILLA LUZ ECOSYSTEM

As seen on the map, a river rich in H2S enters the cave in its more distal parts (left side) and H2S is also seeping from cracks in the soil connected to deep volcanic sources and pockets of gas. The river flows through the whole cave from left to right and exits through the entrance. On its way, it creates a series of small ponds. MAny fishes live in the ponds closest to the entrance (sardines, the Indian name of the cave is indeed "cueva de las sardinas"). This unusual abundance of life is easy to understand. These fishes eat all sort of living matter flowing out from the deeper recesses of the cave and transported by the river.

Indeed, the Cueva de Villa Luz's fishes are linked, as upper level predators, to a highly astonishing and extensive food web living in the dark in the ponds and passages farthest from the entrance. Thefood web members depend for energy not on photosynthesis from sunlight (there is none) but on an inorganic chemical process: oxidation of sulfur compounds.

When the explorer James Pisarowicz first entered Cueva de Villa Luz in 1987, he was flabbergasted by its "out of this world" geochemical features. The following description is modified from his paper: "Everywhere I saw yellow sulfur, white gypsum crystals, and colored slimes coating the walls. The "rotten egg" odor of hydrogen sulfide was almost unbearable. Hanging from the ceilings were strange stalactites that dripped sulfuric acid. Their examination showed later that they were massive colonies of sulfur-oxidizing micro-organisms. They looked really like rubbery stalactites made of mucus, so I dubbed them "snottites"...

You might have explored caves for years everywhere in the world, nothing prepares you for Villa Luz.

Indeed, as I have said before: it is hypogenic.

This means that it is not, like most caves carved out from entrance to bottom by carbonic acid, the compound that forms when rainwater picks up carbon dioxide from the air. In these normal” caves, the mild carbonic acid, the same we drink in beer and soda, seeps into the limestone cracks and, over geologic times, dissolves the rock and widen the caves forming the passages, pits and rooms we are used to see in caves.

Villa Luz like a few other caves in the world tells us a totally different geochemical story. These caves have not grown from mildly acidic waters coming from the surface. Instead, they have been, at least partially, carved by the strong sulphuric acid and chemical reactions made possible by the high sulfur content of the water rising from cracks in the soil connected to deep volcanic chambers in the earth crust.

Such hypogenic caves (i.e. formed from below) may, for millenia be carved by the acid coming from the deep earth’s crust without any connection to the outside world, no oxygen connection. They may exist as chambers totally isolated from outside and thus unknown to us.

Obviously, Villa Luz is not isolated... but one knows such an isolated hypogenic cave, called Movile Cave in Romania(we will study it in another post). Imagine an isolated cave, without any communication with the surface, filled with gases and strange animals, somewhere underground.

Now anhypogenic cave may not stay isolated forever. If there is deep water rising in the cave, it may slowly carve a way out and meet a surface cave. Then we will have a sulfurous spring somewhere.

Of course nothing precludes also such an isolated cave to encounter after many millenia a normal flow coming from the surface and having formed a normal cave. Then we have a mixed situation where some parts of the cave are hypogenic and other are formed from the surface. Villa Luz might be such a cave (or is it formed only by deep waters flowing out?).

On the map given above, you see a series of rooms and ponds going from the deepest parts to the entrance. The ones close to the entrance have obviously an atmosphere rich in oxygen (see the pits). Eexcept for the richer than usual life present in them, they have many characteristics of normal caves at these latitudes. As you travel deeper and deeper into the cave, you go into more and more strange passages, more and more characteristic of hypogenic caves: a choking atmosphere, drops of skin burning sulphuric acid, and most astonishingly, a teeming life.

Indeed, hypogenic sulfur-based caves are not formed solely by inorganic chemical reactions (rock dissolution by acid). They are also carved and, literally, made by the enormous quantity of microbial life forms they support. Basic in these life forms are the bacteria. They derive their energy from inorganic chemical reactions (literally, they are rock eaters). They metabolize the H2S dissolved in the water and use the oxygen from the CO2 in the cave's atmosphere to produce sulfuric acid, a strong acid indeed since it is the one used in car batteries.

Question: I am not at all clear about the last sentence. Where does this oxygen comes from in truly hypogenic caves, from CO2? Then where is CO2 coming from? I am just no enough of a chemist to know. What is a truly sensible reaction mechanism?

The sulfuric acid then reacts with the rocks. It does not completely dissolve it but converts limestone into gypsum (calcium sulfate) forming beautiful white crystalline structures (needles, trees…). Gypsum falls into the stream and, being very soluble in water, it is then transported out of the cave. With time, more limestone is transformed into gypsum and the cave widens.

Indeed, sulfur-eating bacteria form the basis of the ecosystem (food web) of Villa Luz. They oxidize sulfur to get the energy they need and use thus carbon dioxide, water, and sulfur as the basis for their life. These sulfur eating bacteria are not isolated. Other bacteria eat them. All together, bacteria form huge mats and biofilms (veils in water, mats on rocks, snottites). Small invertebrates (e.g. innumerable midges and worms) graze on these slimy mats. Spiders prey upon the bacteria eaters.

As we have said before, the most spectacular form of bacterial biofilm found in Villa Luz is made by “Snottites”, slimy, rubbery chandeliers hanging from the ceiling or the walls and made entirely from many species of coexisting bacteria and a a complex biofilm structuring material. Small worms and mites live within and on the snottites; spiders walk their nooks and crannies.

The fishes in the external ponds (Poecilia mexicana) eat midges and sulfur-oxidizing bacteria.

As you see from the maps, Villa Luz has many entrances through which skylight can come in and visiting bats can fly and prey upon the ecosystem. This certainly couples Villa Luz’s ecosystem to the outside world and makes the story of Villa Luz much more complex than the one of a purely hypogenic cave. Nevertheless, it clearly shows how a sulfur based, oxygen fearing ecosystem can develop in an hypogenic cave. I will need such a cave, truly hypogenic in some parts but communicating with the outside world in other.

This is all I want to tell you for now about Villa Luz. In the next post we will discuss another hypogenic cave, a much purer one, Movile cave in Romania.