A PERMIAN PALEOBOTANICAL POMPEII

There is a mythology of sorts about finding dinosaurs.  Every skeleton is beautifully complete from the tip of the snout to the end of the tail. Each bone is in its life position. The most delicate feature is preserved uncrushed.  This propaganda is furthered by films, such as the Velociraptor excavation scene in Jurassic Park.  If only it were so.  Most of us deal with skeletons much less complete and more difficult to interpret.  But the beautiful specimens get the better press.  That’s understandable. 

The situation is worse with plant fossils. Leaves and twigs, cones and flowers, roots and trunks, and all other plant parts become easily separated and scattered by water and wind or are quickly destroyed. Finding a cone attached to foliage might allow you to connect it with a branch preserved with that kind of foliage attached which might allow you to connect it to a trunk with that kind of branch attached. Such a series of fortunate discoveries will allow you to reconstruct what the total plant looked like.  Bigger questions, such as what the total plant community was like, how closely spaced or scattered were the different plants, or what was the relative abundance of the different plant species require yet more remarkable preservation, that of a whole forest. A just published paper provides just such a rare insight into an ancient coal swamp in Inner Mongolia.

Being able to accurately reconstruct how an ancient plant community is structured requires rapid burial of the forest, something on the order of hours or days, and with no transport of the dead plants.  For such a special situation one needs the help of a volcano, and a special kind of volcanic eruption at that -- a volcanic ash fall like that of Mount Vesuvius which buried the famous Roman cities of Pompeii and Herculaneum in 79 AD.

Just such a large eruption occurred some 298,000,000 years ago near what is now Wuda in Inner Mongolia.  The ash fell onto a Permian peat - coal swamp.  As the ash fell it broke off branches, twigs, leaves, and cones, toppled trees, and eventually buried the forest in-place under a 100 cm (~40 in) thick ash layer.   The floor of this forest was a thick layer of peat composed of partly decomposed plant material permanently under several centimeters of acidic water.

1. The 80 foot tall Sigillaria (A) and slightly shorter Cordaites (B) were the tallest swamp trees at Wudan.

The quality of preservation at Wuda is outstanding and provides a fantastic record of the plant life.  Because the heights of many of the plants can be determined with confidence, we get insight into the vertical structure of the forest. The tallest trees (Sigillaria) towered over the rest of the trees, growing as tall as 25 m (82 feet) forming a sparse upper canopy.  The slightly shorter Cordaites is a primitive conifer-like tree.

2. Several species of tree ferns, at a height of 10-15 meters (32-50 feet), formed an actual canopy across the swamp.

3. The enigmatic Noeggerathiales (A) and several types of primitive cycads (B) were shorter trees forming a lower canopy in the forest.

4. In areas where the water was very shallow or the peat emergent, sphenophytes  (A Sphenophyllum, B Asterophyllites) and ferns (C) formed a sparse and patchy ground cover.

While this fossil site gives us a remarkable amount of information, it includes more treasures. Because it was fossilized in-place over a short period of time by an ash fall, the bases of the trunks and roots of plants were preserved in life position. This allows us to reconstruct how the different types of plants were distributed across the swamp.

5. A reconstructed part of the Wudan swamp forest showing the vertical structure and horizontal distribution of the plant life.  The tallest plants (Sigillaria) reached heights of 80+ feet. Water covered the forest floor for most of the year.

 Wang and his co-authors were able to map 1000 m² of the ancient swamp floor and record exactly where each type of plant lived.  In modern day living forests, such mapping on the scale of 200-500 m² is considered sufficient for characterizing the forest structure.  To be able to do twice a well in a 298,000,000 old forest is just remarkable.

6 Another reconstructed area of the Wudan swamp forest showing the variation in the structure of the plant community.  As in 6, the tallest plants are 80+ feet and water covered the forest floor for most of the year.

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Not all fossil forest are like that at Wuda. Petrified Forest National Park is probably the most famous fossil forest in the world.  However, the abundant and sometimes immense logs are not preserves in life position.  The downed trees were transported and  buried in ancient river channels --  a fossilized log jam of sorts.

Specimen Ridge in Yellowstone National Park is an eight mile long cliff face with dozens of fossil forests exposed on its 2000 ft vertical surface.  While these forest are piled up on one another layer by layer, no single flat surface is exposed that shows how the trees were distributed across the forest floor.  This begs the question “So how were paleobotanists able to map the fossil plants at Wuda?  The answer is simple --- mining.

7. Aerial view of the Wudan coal mining operation (dark areas). 

The Wuda forest is located between coal seams numbers 6 and 7 in the Wuda coal field. The ash can be seen in cross section in mine tunnels.  But to conduct the kind of study done there, a great deal of overlying rock had to be removed to get to the forest layer, at firt through normal mining information and later by the intensive and rapid mining associated with efforts to put out a severe coal mine fire. As the mining operations progress, they remove layer after layer of coal, eventually providing access to hundreds of square meters of the ancient forest floor.  A power shovel was used to break the ash layer into blocks that were then split by hand and their contained fossils mapped on a grid system. The stunning fossils needed to be quickly collected because erosion was rapid once the rock surface was exposed.

Mining operations are often quite destructive when it comes to fossils. Fossils are destroyed simply by the very act of excavating vast amounts of rock from deep in the earth.  However, there are times when mining operations enable paleontologists to study a record of the past that would otherwise never have been seen.  Several other forests like that at Wudan have been similarly studied in mines in the Czech Republic, Spain, and Germany (1, 4).

8. Track expert extraordinaire, Dr. Martin Lockley, working deep underground on a giant hadrosaur footprint in the roof of a coal mine.

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Mines can reveal more than just plant fossils. Martin Lockley and his colleagues have studied hadrosaur dinosaur footprints preserved in the ceilings of coal mines in Utah and Colorado.  I have had the opportunity to go into a coal mine and see those tracks and they are amazing.  Tracks are sometimes bolted in place onto the ceiling to prevent them from falling and injuring or killing miners (4).

9. Barnum Brown's drawing showing how he collected large slabs of rock containing hadrosaur footprints from the roof of a coal mine.

Barnum Brown collected slabs containing dinosaur tracks from a mine in Colorado and the slab is on exhibit in the Dinosaur Halls in the American Museum of Natural History (5).  Several large sauropod dinosaur footprint bearing surfaces have been exposed by strip mining and stone quarrying in Europe and some of these have now been set aside and preserved as National Parks!!

Photos

Header: Reference 1.
1A:

1B:  http://www.ucmp.berkeley.edu/IB181/VPL/CorCon/CorCon2.html

2:  http://woostergeologists.scotblogs.wooster.edu/2011/10/

3A: Reference 2.

3B: http://taggart.glg.msu.edu/bot335/cycads.htm

 4A: http://fellner.dynalias.net/Geo/An%20I/Paleobotanica%20si%20palinologie/paleobot/c2-pterydofite/foto/ferigi/

4B: http://geologie.vsb.cz/paleontologie/paleontologie/Fytopaleontologie/VYSSI%20ROSTLINY/Asterophyllites.htm

4C: Reference 1.
5: Reference 1
6: Reference 1.

7: http://img.gawkerassets.com/img/17ebpv0fzviahjpg/original.jpg

8: Reference 4.
9: Reference 5.

Sources

(1) Wang, J., Pfefferkorn, H.W., Zhang, Y. and Feng, Z. 2012. Permian vegetational Pompeii from Inner Mongolia and its implications for landscape paleoecology and paleobiogeography of Cathaysia.  Proceedings of the National Academy of Sciences Early Edition: 1-6. Freely available on-line: www.pnas.org/cg/doi/10.1073/pnas.1115076109

(2):   Wang, J., Pfefferkorn, W.H., and Bek, J.  2009. Paratingia wudensis sp. nov., a whole noeggerathialean plant preserved in an earliest Permian air fall tuff in Inner Mongolia.  American Journal of Botany 96: 1676-1689.

(3) DiMichelle, W.A., Falcon-Lang, H.J. 2011. Pennsylvanian “fossil forests” in growth position (T⁰ assemblages): origin, taphonomic bias and paleoecological insights.  Journal of the Geological Society of London 168: 585-605.

(4) Lockley, M.G. and Hunt, A.P. 1995. Dinosaur Tracks and other Fossil Footprints of the Western United States.  Columbia University Press, NYC: 338 pp.

(5) Brown, B. 1938. The mystery dinosaur.  Natural History 41: 190- 202.

LA TRAGEDIE DE LASCAUX: QUATRIEME PARTIE

1. The Passageway, Lascaux Cave.

The artwork in Lascaux quickly become the most famous Paleolithic site in the world.  It was strikingly beautiful and its location in a cave was stunning and furthered its sense of the mysterious.  However the cave became a victim of its own fame and was being loved to death. Cave environmental change and associated degradation of the artwork due to heavy visitation resulted in the cave being closed to public in 1963.

2. The detrimental effects of heavy visitation caused the cave to be closed in 1963.

 In spite of this closure many people still wanted to see the artwork and the closure would have a severe economic impact on the region. Under these pressures the French government came up with a remarkable solution, one never attempted before.  The decision was made to replicate the original cave in what would become known as Lascaux II. Duplicating the cave would not be an easy task. Ultimately it would take twelve years, twenty artists, and about 500 million francs. But millions would again be able to have some kind of Lascaux experience. 

To match the original as closely as possible Lascaux II was located underground in a nearby abandoned quarry only about 250 meters from the original cave. Even the entrance to this replica matches that at the real Lascaux.

3. The entrance to Lascaux II.

Although Lascaux is a relatively short cave, not all of the two levels of the cave could be reproduced.  Efforts focused on The Great Hall of the Bulls and the Axial gallery, two of the most striking parts of the cave.  This would replicate about a third of the total cave and a large portion of the paintings, some 200 over a length of 128 feet. To enhance the cave experience, the air temperature in Lascaux II is kept at 55^oF. 

4. The outer shell of the replica of the cave, Lascaux II, during construction.

 Stereophotogrammetry was used to make millimeter precise measurements of the surface of the cave walls. A metal framework was built and overlain with three layers of chicken wire.  Special cement and mortar was then applied to this surface and the stereolithographic measurements were used to sculpt the surface to match the original. 

5. The replicated Hall of the Bulls at Lascaux II.

Next came the actual replication of the artwork.  Monique Peytral, the painter, projected images of the original figures onto the walls. Peytral used the same kind of pigments as the Paleolithic artists, based on materials found in the area surrounding the cave.  She also used the same types of tools, such as feathers, chewed plant stems, animal fur, etc. Work to make Lascaux II began in 1970 and the finished replica opened to the public in 1983.  Today it receives some 300,000 annual visitors.  

6. Photographs projected onto the false cave walls allowed for the most accurate replication of the paintings.

In 2003 the General Council of the Dordonge began a project to replicate scenes from The Nave part of Lascaux, an area not in Lascaux II.  In 2008 these copies were put on exhibit and then went abroad as a traveling exhibition.  It was permanently installed in the Toth Prehistoric Park in the nearby town of Thonac.  In addition to the artwork, this park includes a video of how Lascaux II was constructed, and living examples of the animals seen in the Lascaux paintings

 The Frieze of the Stags Heads, a Lascaux painting of five stags, was duplicated for the World’s Fair in Japan in 1990.  This duplicate frieze in now on permanent exhibit in the Hall of Biology and Human Evolution at the American Museum of Natural History in New York City.

7. The replica of the Frieze of the Five Stags.

8. The replica of the Frieze of the Five Stags on exhibit at the American Museum.

Unfortunately, the parking lot for Lascaux II was built directly over Lascaux Cave.  There are now concerns about both pollution of the cave from the lot and how the paved surface affects natural water flow into the cave. So the parking lot will be relocated.

And in a final bit of irony, the heavy visitation at Lascaux II has resulted in some degradation of the replica so that it too is now in need of conservation.

This is the last of my posts about Lascaux.  As I said in the first post, Lascaux concentrates many problems of resource management, resource preservation, public education, and science, all issues close to my heart and which I have dealt with during my professional career.  Lascaux offers a sobering look at how sites can be loved to death, becoming victims of their own fame and success.  How the environmental and microbial problems in the original cave will resolve themselves is uncertain, although the future is hopeful.  The success of the innovative Lascaux II, both in terms of preservation of the original art and public visitation, has been adopted elsewhere where cave art is threatened by too much visitation. Replication of the cave art at Altamira was replicated in 2001.

PHOTOS

1:  http://www.lascaux.culture.fr/

2:  http://www.bestourism.com/items/di/7999?title=The-cave-of-Lascaux-France&b=355

3,  6:  http://www.donsmaps.com/lascaux.html

4:  http://www.lascaux.culture.fr/

5:  http://ofrancji.com/tag/co-warto-zobaczyc-w-poludniowo-zachodzniej-francji/

7.  http://www.donsmaps.com/lascaux.html

8.  http://www.amnh.org/exhibitions/permanent/humanorigins/human/art.php

SOURCES

Lascaux: http://www.donsmaps.com/lascaux.html

Lascaux caves: http://www.sacred-destinations.com/france/lascaux-caves

What makes us human?: http://www.amnh.org/exhibitions/permanent/humanorigins/human/art.php

FOSSILS IN FLAGRANTE DELICTO: A VERY SPECIAL PALEONTOLOGICAL SALUTE TO VALENTINE’S DAY

1. It just gets better as you get older. A scanning electron microscope photo of a 600,000,000 year old  4 cell embryo from China. Embryo is .65 mm in diameter (0.02559055 inches)

Evolution has only four basic requirements; an organism needs to reproduce, the offspring need to be different from one another, the differences need to be inheritable, and differential survival among the offspring is due to those inherited differences. In celebration of Valentine’s Day, let’s see what the fossil record can tell us about the first of these.

Paleontology is full of the flotsam and jetsam of reproduction.  Dinosaur eggs and nests, fossil female rhinos and whales with preserved skeletons of fetuses preserved within their rib cages, morphological sexual dimorphism (where the males and females look quite different), PreCambrian single cell organisms preserved in the act of dividing, microscopic multicellular marine invertebrate embryos, and pollen and spores are just a few examples. However, what is really rare are fossil organisms preserved in copulito (the technical term for “doing it”).  But under the right conditions even such a transient behavior can be preserved.

2. Love's eternal embrace.  A mating pair of black scavenger gnats in 25,000,000 year old Dominican amber.

Amber is fossilized plant resin or “sap”.  The sap is exuded by the plant to seal external injuries and keep infectious organisms out.  Huge amounts of resin pour from entire forests trees when there is large scale damage from fires, storms, outbreaks of boring insects, etc. The resin is sticky when exuded and hardens slowly, sometimes taking thousands of years after burial to become amber. Amber is known as far back as the Carboniferous, some 300 million years ago.  The bulk of fossil amber dates from the Triassic and most of that is from conifers (such as pines) although a few large Cenozoic amber deposits come from broad leafed trees. Humans have known of amber and used it for jewelry and decoration for some 13,000 years. 

3. Two fossilized copulating  gnats in  amber.

Resin preservation is spectacular, showing exquisite details such as sensory hairs, color patterns, even small parasitic mites attached to larger insects and bacteria in insect guts. Even more impressive is the preservation of cellular and subcellular details such as muscle and nerve cells and even mitochondria!!

4. Two unidentified  amber entombed wasps copulating. The smaller individual on the left is the male.

5. Don't you guys ever get tired of looking at that stuff? A pair of mites (Glaesacarus rhombeus) in amber go at it for eternity.

Well how did our ancient lovers of today’s post come to be?  It’s when the resin is most sticky that is of interest to us.  At this stage it can flow over and envelop slowing moving animals or entrap anything that lands on its surface. Insects and other arthropods are abundant in forests and so, not surprisingly, are the most common type of amber inclusion. 

6. The fearsome "penis" of a male seed beetle.  The frightful array of spines sometimes punctures the genital tract of the female during copulation.

Male insects can have remarkably complex "penises", wonderfully twisted, contorted, bedecked in a coat of fearsome spines, and looking more like a scifi movie monster than a reproductive organ.  These complex penises fit tightly into the reproductive tracts in the female, a lock and key type of mechanism that helps insure that mating only occurs between members of the same species.  Females play the field and often copulate with multiple partners, so its in the male’s interest to try and stay attached as long as possible to the female to ensure that’s it’s his sperm that fertilize the eggs.  The complexity of the reproductive organs helps keep then attached.  It’s not true love, but it works. It also gets you trapped in amber. 

For those of you interested in exploring the truly astounding diversity of animal reproductive behavior and the evolutionary reasons for such, one can do no better than Olivia Judson’s delightful book Dr. Tatiana’s Sex Advice to All Creation. Judson is an Oxford Ph.D., an outstanding writer, and quite adept at making the technical side of evolutionary biology understandable.  She is damn wickedly clever too.  The book is set up as a series of love advice columns of a fictitious Dr. Tatiana, with each chapter containing letters from concerned organisms about his or her mate.  One of my favorites is from Chapter 1 A Sketch of the Battlefield:

“Dear Dr. Tatiana,

My name is twiggy and I’m a stick insect.  It’s with great embarrassment that I write to you while copulating, but my mate and I have been copulating for ten weeks already.  I’m bored out of my skull, yet he shows no sign of lagging. He says it’s because he’s madly in love with me, but I think he’s just plain mad.  How can I get him to quit?”

Some years ago the book was made into a two part miniseries for the BBC, but I haven’t yet found it in a format I can play in the US.

For a more technical discussion, see Thornhill and Alcock’s The Evolution of Insect Mating Systems. Although a detailed scientific work, it is not without some humor, such as the photograph of a male burpestid beetle trying to copulate with a discarded brown beer bottle some 5 times his size.  Presumably the bottle has some key visual properties that reminded him of conspecific females and triggered the mating attempt. 

7. Lust in the Australian desert.  Passionate male burpestid beetles will die from the heat as they try unsuccessfully to mate with a "Big Momma" beer bottle. Note genitalia projecting from the tip of the abdomen.

Finally, for those of you interested in movie trivia, the opening of the first Jurassic Park movie shows a mosquito being overwhelmed and trapped in resin (actually honey).  A friend who is an entomologist and works on dipterans (flies, mosquitos, and their ilk) pointed out to me that the dipteran in the scene is a tipulid (crane fly) and not a mosquito.  Adult tipulids feed on pollen, not blood.  However, they are quite large and thus easy to film. 

Photos

1: http://www.science.vt.edu/news/magazine/fall10/xiao-fall10-article.html

2. Reference 1 below.

3. http://www.prices4antiques.com/natural-history/fossils/Fossil-Amber-Slab-Flies-Mating-Eocene-Russia-05-inch-D9736281.htm

4.  http://snakefly.tripod.com/index-2.html

5.  http://news.discovery.com/animals/40-million-year-old-sex-act-captured-in-amber.html

6.  http://scienceblogs.com/corpuscallosum/2007/08/bizarre_sex_organs.php

7. http://howanimalsdoit.com/2011/10/06/bug-sex-friday-beetles-seduced-by-beer-bottles/

 
Sources

1. Grimaldi, D. and Engel, M.S. 2005. Evolution of the Insects. Cambridge University Press: 755 pp.

2. Judson, O. 2002.  Dr. Tatiana’s Sex Advice to All Creation. The Definitive Guide to the Evolutionary Biology of Sex.  Henry Holt and Co.: 308 pp.

3. Poinar, G. 1992. Life in Amber. Stanford University Press, Stanford: xii + 350 pp.

 

4. Poinar, G. and Poinar, R.  1994. The Quest for life in Amber.  Helix Books, Reading:  xiii + 219 pp.

5. Thornhill, R. and Alcock, J. 1983.  The Evolution of Insect Mating Systems. Harvard University Press, Cambridge: 547. 

IS THIS THE FIRST NEANDERTAL CAVE ART?

1. Three of the recently discovered seal drawings in Nerja Cave.

A story appeared in today’s news proclaiming that the first examples of Neandertal cave art have been discovered in the Nerja Caves along the south coast of Spain.  These caves started forming 5 million years ago. Human occupation of the cave begins about 25,000 years ago and the oldest cave art in the cave is about  21,000 years old. 

The newly discovered paintings consist of a series of six figures drawn in red pigment on a stalactite.  These relatively crude images are interpreted as being of seals, which would have been a food source available at that time along that Nerja coast.  Unspecified organic residue found next to the paintings has been tested and yields a date of 42,3000 to 45,300.  If this date is correct, it predates the oldest cave art at Chauvet Cave by over 10,000 years. 

This date is older than the otherwise oldest human remains or artifacts in the Nerja cave and is within the time frame of the existence of Neandertals. Thus, the claim is being made that this is Neandertal artwork, the first such found anywhere in the world.  It would suggest Neandertals had  more complex intellectual abilities than previously thought.  So this might be a very important discovery.  Might be.  

2. A powerfully built Neandertal skeleton.

 Who Were The Neandertals?

Neandertals are fossil humans that ranged across Europe and the Middle East, eastward possibly as far as the Ural Mountains. Geologically, they lasted about 100,000 years (135,000 – 30,000 years ago).  Their skeletons were more robust than those of modern humans.  Neandertals reached an adult height of between 60 and 66 inches. They were not the caveman brutes of popular imagery. Neandertals are known to have made stone tools and weapons, build structures, control fire, and skin animals.  They lived in complex social groups.  The morphology of the hyoid bone in Neandertals, the bone that anchors tongue muscles to the larynx, is nearly identical to that in modern humans, suggesting that they may have been able to produce a wide range of sounds.  Although Neandertals built dwellings out of mammoth skulls, tusks, and bones, they also frequently lived in caves.

Neandertals are often classified as their own species, Homo neanderthalensis.  However, recent sequencing of the neandertal mitochondrial genome indicates that between  1-4% of modern human genes are inherited from neandertals, suggesting that there was limited interbreeding between H. neanderthalensis and H. sapiens.

The Nerja Cave And The Artwork In Question

Although the Nerja caves were occupied by primitive humans, their modern rediscovery occurred in 1959.  The caves have since been extensively developed for tourism.  One area, the Hall of the Ballet ,has 100 seats permanently installed in the cave floor and is the site for concerts and dance performances.  Much of the cave art is in other areas of the cave that requires specialized caving techniques to get to, although “spelunking tourism” goes to those areas.  The news stories do not say where in the cave the new artwork was found.

3. No caving skills required! Stairs, lights, and concrete walkways make  a visit to Nerja Cave easy and convenient.

 

Although the image of artwork is striking, there are some troubling questions about the discovery.  First, the date is for unspecified “organic material” found near the artwork, not of the artwork itself.  The organics may well be 43,000 years old but they may have no relationship to the artwork.  Second, the artwork is done in red pigment, which is the iron oxide hematite, a naturally occuring mineral frequently used in cave art (as we have seen for Lascaux).  Hematite is not an “organic substance” which further suggests that the organics dated have nothing to do the artwork.  Although the story says that dating of the artwork is a future goal, there is nothing in hematite that can be dated. 

Most telling however is the appearance of the artwork on the surface of the stalactite.  It is a strong red color and appears to be on the surface.  However, stalactites grow as water drips in the cave, runs down the stalactite, and deposits calcium carbonate minerals as the water evaporates.  The crispness of the seal drawings suggests that there has been no stalagtite growth for the last 40,000 years.  While this is remotely possible, it is not likely.  Moisture can be seen on other stalagtites in the photo, so growth is still going on in that very part of the cage. One would expect artwork as old as claimed to be less distinct because of overgrowth by calcite. Finally, the story appears to be based on a press release and there is no indication that the find has been through rigorous peer review and publication in a scientific journal, where some of these questions would be raised and answered.

The discovery of incontrovertible Neandertal cave art would be both fascinating and important. Are the seals of Nerja Cave neandertal paintings?  It seems the evidence presented to date is equivocal and the jury is still out.   Hopefully future work will provide a definitive answer. 

Photos

1 and 3: http://www.dailymail.co.uk/sciencetech/article-2097869/The-oldest-work-art-42-000-year-old-paintings-seals-Spanish-cave.html?ito=feeds-newsxml

2:  http://en.wikipedia.org/wiki/Neanderthal

Sources

1. Tim Worden.  The oldest work of art ever: 42,000-year-old paintings of seals found in Spanish caves. The Mail OnLine.

http://www.dailymail.co.uk/sciencetech/article-2097869/The-oldest-work-art-42-000-year-old-paintings-seals-Spanish-cave.html?ito=feeds-newsxml

2. http://en.wikipedia.org/wiki/Neanderthal

LA TRAGEDIE DE LASCAUX: TROISIEME PARTIE

1. The Great Hall of the Bulls.

The damage and degradation of the fantastic cave art of Lascaux is a long, complicated, and depressing tale. Caves systems are remarkably fragile environments that are easily disturbed, often irreparably. Ignorance, greed, good intentions, poor oversight, denial of problems, organizational rivalries, cover ups, actions taken with no scientific evaluation, public fascination and desire to see this great human legacy --  all contributed to what happened in the cave. 

How to tell this story in a reasonably short post is a challenge.  I decided that a long narrative piece would actually reduce the impact of what transpired.  I have opted for a more telegraphic, chronological approach because that is simpler and makes it easier to see and understand the cascade of events.  It also emphasizes the compexity of the problems Lascaux faces and the difficulty in preserving the cave and its artwork.  It seems that in spite of all the efforts, heroic and otherwise, the future of the Lascaux artwork remains, unfortunately, somewhat uncertain.

What is clear is that the environment of Lascaux that preserved the artwork is irretrievably gone.  The enlarging of the cave opening, the high public visitation, and other factors ensured that.  Efforts to try and recreate that original environment are futile.  The goal now is to stabilize the cave environment and to avoid the massive shifts that have occurred since 2001. That will end the repeated microbial outbreaks that threaten the artwork and allow a program to be developed and implemented that will ensure the long-term preservation of Lascaux.

Finally, the cave paintings and etchings do not exist in isolation.  They must be preserved in their context, in this case the cave and its environment. The walls and ceilings are the canvas for the art.  Is those are damaged or destroyed some part of the artwork is lost, as well as some of the potential to understand this priceless heritage.   The problem is not to just to prevent damage to the art, it is to preserve the cave in its entirety.

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1940

On 12 September, the dog Robot, accompanied by four French teenagers, discovers the cave of Lascaux and its paintings.  For 18,000 years these paintings had been sitting in a stabilized cave environment, in an equilibrium that preserved them.  That had now come to an end. 

In December of that year the French government designates the cave a Historic Monument.

2. Some of the first visitors in 1940 shortly after discovery.

 1947

3. Building the entrance, 1947.

The cave is developed for public access. The entrance is widened, a concrete entrance ramp built, a bronze door installed, electricity is run into the cave for lighting, and the floor of the cave lowered for steps leading directly down to the Hall of the Bulls. To do this work, some 600 cubic meters (22,000 cubic feet) of rock and sediment was dug out and removed.

That work removed the cone of soil and rock that buffered the cave. The cave and its environment had now been completely disturbed. Cave development was spurred on by both the intense public interest in seeing the cave paintings and the desire for economic development in a rural part of post-war France.

  1948

Lascaux opens to the public on July 14 and receives as many as 1700 visitors a day. This is an impressive visitation number given the remoteness of the cave and general transportation at the time. 

 1949

First signs of mold seen.

 1950

Two airlocks are installed at cave entrance.

 1955

Visitation reaches 30,000 people per year.

The first signs of deterioration appear in the cave due to excess carbon dioxide, elevated temperatures, and intermittent condensation of water on the walls. This is the result of  the large number of visitors.

1957-1958

The first air-conditioning system is installed. Some 440 cubic meters of earth and rock are removed for the project.

1960

 Visitation reaches over 100,000 per year.

The changes in humidity and carbon dioxide cause the growth of algae (Bracteacoccus minor) on the walls of the cave. This is given the name “The Green Sickness”.

At the same time, the mineral calcite begins to form over the paintings due to condensation on the surfaces.  This is given the name “The White Sickness”.

4. The White Disease, calcite encrusting the walls.

 1962

The growth of the green algae is such that it is now observed growing next to, and threatening, some of the paintings.

1963

Because of the negative effects of high visitation on the cave and the artwork , the owner of the cave, Count de la Rochefoucald-Montbel, closes the cave in January. The government forbids the April reopening planned by the owner.

In addition the air-conditioning system is turned off.  It is hoped that these actions will stop the cave degradation.

In March a Committee for the Study and Preservation of the Lascaux Cave (CSPLC) is established.  It includes prehistorians, hydrologists, physicists, microbiologists, and curators and works to develop an intervention strategy for the cave’s problems. It meets regularly until 1976.

1963-1965

A program of spraying antibiotics (streptomycin and penicillin) directly on the walls to kill bacteria begins.  This is intended to kill the microbes, but after the second application the treatment proves ineffective.

Following the recommendation of The Pasteur Institute, formalin is applied to affected areas in the cave. This successfully eliminates The Green Sickness but does nothing to stop The White Sickness.  Formalin is a 40 per cent solution of formaldehyde (a known carcinogen in humans) mixed in water, which is used as a disinfectant, preservative for biological specimens, etc.

1965 – 1967

A new cooling system is installed based on the recommendation and study of the CSPLC. This system is designed to reduce condensation and have less impact on the cave environment because it works by convection with cave’s natural air currents.

1976

Declaring Lascaux stabilized, the CSPLC disbands.  The cave remains closed to the public.

1995

A White Paper by the cave’s curator notes the failures of the cooling system installed in 1967. It underscores the need to limit cave visitation and installation of a new climate control system.

1998

Research scientists notice lichens growing inside the cave.

1999

A decision is made to replace the air conditioning system installed in 1965-1967.  Although that older system used the natural air currents of the cave to stabilize the cave’s climate, the new system will use a totally different method, that of forced air. 

 2000

The installation of the new air conditioning system begins. Teams of workers installing the system work unsupervised in the cave on a daily basis. 

5. The air unit installed in 1999-2000.

Weeks after the installation begins mold (fungi) appears on the walls of the engine room inside the cave.  Because of the appearance of fungi, the thermal insulation is removed from the system, which alters its effectiveness. It is thought that the cave was contaminated with the mold by the unsupervised workers who did not sterilize their boots when entering the cave.

It is now generally agreed that the new air system, because it worked via forced air, was the catastrophic act that destabilized the cave’s environment and disrupted the natural air currents within the cave.  This led to the explosive microbial infestations and other disasters over the following decade.

 2001

The new air condition system is completely installed.

In a second major microbial crisis, the fungus Fusarium solani  and its associated bacterium Pseudomonas flourescens has colonized and spread across the cave, forming a white coating over the floor and ledges. This fungus is common in agricultural areas, such as those surrounding Lascaux Cave, further suggesting it was brought in on the unsterilized boots of the workers.

Massive amounts of antibiotics and fungicides (streptomycin, polymyxin, benzalkonium chloride) are sprayed on the affected areas, but this proves ineffective. The application leaves large spots, up to six inches across, on the walls. Within weeks after the spraying the fungus reappears and quickly develops a resistance to the antibiotics being applied.

Cloth compresses soaked in fungicides and antibiotics are applied directly to the cave’s walls.

6. Biocide soaked sheets on unpainted cave walls.

When it is realized that the biocide and fungicide applications are not working, an emergency effort is implemented. Quicklime is spread all over the cave floor. The intent is to sterilize the ground and stop mold growth.

7. Quicklime on the floor near the entrance to the Hall of the Bulls.

Quicklime is a caustic calcium oxide and releases significant heat when reacting with water. As a result, the application of the large amounts of quicklime causes the cave’s interior temperature to rise.  Because of its strong reaction with water, quicklime can cause severe irritation when inhaled if it is in contact with moist skin or eyes.

Recognizing that the just installed forced air system is not appropriate to the cave environment, authorities shut most of it down.

 2002

Dark spots now begin to appear on the ceilings of the decorated chambers.  The decision is made to start invasive mechanical removal of the fungus, scraping and pulling fungal “roots” (hypae) out of the rock by hand.  This work requires bright lights, which affects the cave’s temperature.

The massive spraying of antibiotics is terminated.

The French Ministry of Culture appoints a new scientific commission which is to examine the impacts of previous emergency measures on the paintings and develop a strategy to stabilize the cave environment.

2003

Mechanical removal of fungal hyphae continues, resulting in teams of workers continually inside the cave.

The problems at Lascaux captures the attention of the press, with exposés appearing in  La Recherche, Le Point and The Wall Street Journal.

2004

The new scientific committee releases its plan with short, medium, and long term components.

A 3D survey of the cave begins. This is intended to document baseline conditions so that changes and effectiveness of actions can be evaluated.

8. Scaffolding erected as part of the cave survey.

 2005

Although the growth of fungi is slowed by the program of mechanical removal, the fungi are not eliminated.  Teams continue to work inside the cave.

The 3D survey of the cave is completed.

An exhaustive and detailed survey begins to document artwork and etchings throughout the cave.  Work is carried out by art restorers with assistance from geologists.

A digital simulation of the cave is developed to model how the addition of equipment, changes in air flow, etc. will affect the cave environment.  This will help decide what kind of air regulation system should be installed in Lascaux.

Hydrologists begin a study of condensation and groundwater movements to understand what role they may have played in growth of white mold and black stains.

The International Committee for the Preservation of Lascaux is established. Its goal is to preserve the prehistoric paintings in the cave of Lascaux. It also works to raise public awareness about the deterioration of the cave and the art and stimulate public action to safeguard Lascaux’s artwork and interest scientists from diverse disciplines in Lascaux’s preservation.  This organization is not part of the French government and is suspect of much of what the French government is doing at Lascaux.  This relationship becomes  increasingly confrontational over time, with the ICPL charging the French government of a cover-up of the threats and damage to the paintings and etchings.

  

 2006

In what is the third major microbial crisis, large numbers of new clusters of black spots appear near the cave entrance? Although reported, they are not analyzed. By the end of the year they have spread throughout the cave. They begin to cover paintings. Biologists cannot identify what species of mold makes the black spots, do not know what made them appear and grow explosively, and cannot recommend a treatment strategy.

9. Microbiological sampling of a black, discolored area.

 

Removal of fungus by mechanical means continues.  This work is being done by unsupervised teams of three to four people working all day three times a week. Teams consist of art restorers, scientists are not part of the teams. The art restorer work requires additional lighting that raises the temperature.  The number of people and the amount of time they are in the cave are well above the levels known to have impacts on cave environment.

Small meteorological stations are set up in the cave to monitor microenvironment to investigate changes in microorganisms and changes in environment.

There is little scientific follow up. Scientific specialists, such as microbiologists, come only twice a year to the cave.

The workers lean ladders against unpainted parts of the wall.  Ladders of the workers lean against the walls (un-painted) breaking off some ledges. Prehistoric paint drippings on ledges in the Hall of the Bulls are lost when the ledges are accidentally broken off.

The decision is made to remove the quicklime put in the cave in 2001 to control fungal growth. This requires digging up the quicklime.  In some areas the cave floor itself is excavated. 

Calcite mineral deposits are appearing on the paintings themselves, as well as the walls.

Color tones on some paintings are beginning to fade.

The ill-fitted air machine is operating on a partial basis but is not able to stabilize the cave environment.

 The May 16 edition of TIME runs the Lascaux crisis as its cover story: http://www.savelascaux.org/TIMEMagazine.pdf

  2007

The black spots, some as large as human hands, continue to grow everywhere in the cave. The number of spots triples in late summer 2007.  They are still unidentified. Even so, a debate erupts over what to do about them.  Some want to start to again spray antibiotics on the cave walls. Others oppose that because of problems caused by the previous spraying. The decision is made to spray the cave and then close it to all human access.

10. Spraying biocides on part of the cave roof with no artwork on it.

Lab work reveals that the black spots contain melanin which is triggered by light. There is a strong suspicion that the invasion and explosive growth of the black spots is the result of extensive use of lights by the survey and restoration teams that have been working in the cave for the last four years.

The head of the famous Black Cow painting is now threatened and surrounded by the black spots.

Six additional genera of fungi are reported in the cave (Chrysosporium, Gliocladium, Gliomastix, Paecilomyces, Trichoderma, Verticilium).

The air conditioning system is finally completely shut down.

A new study is launched to analyze historic data and draw up specifications for a new climate regulation system.

A temporary roof set up in 2000 to aid in the installation of the air system is exposing the cave to sudden variations in exterior climate and precipitation.

The cave has become very wet. Water is observed running down many of the paintings.

The white calcite which forms the bright canvas for the Lascaux paintings  is turning gray.

Because of the worsening conditions, Lascaux Cave in placed on the World Heritage in Danger list  by the United Nations Educational, Scientific and Cultural Organization (UNESCO).  

2008

Fifty percent of the cave walls are infested with the black dots, including areas such as The Nave and the Passage which contain much artwork as well as the area with 1600 prehistoric engravings (the highest concentration in the world). 

The melanin produced by the bacteria stains the walls and remains even after the bacteria are killed. The melanin might be a permanent alteration to the cave and the artwork.

An experimental approach to remove the melanin is undertaken. This involves physically scraping the walls affected. This scrapping removes the melanin but also the outer surface of the wall, painted or not. New biocide treatments are also started.

After mechanical treatment is completed, a Gregomatic is used to remove residual organic deposits from undecorated areas. A Gregomatic injects pure cold water onto a stone surface and immediately vacuums up the water and the loosened material, and cleans the pores of the rock surface. The Gregomatic is designed to remove dust, dirt, grease, bacteria and poisonous substance from the surfaces.

French National Television claims that the Lascaux crisis is solved.  The International Commission for the Preservation of Lascaux (ICPL) disagrees and condemns the process of scraping the melanin.

Although French officials claim that the cave is reaching a microbiological equilibrium, scientists dispute that. Antibiotic sprays kill some of the bacteria, but the spray contains chemicals that are nutrients for other microorganisms. This further disrupts the microbial community which must reach another state of equilibrium. The problem is that no one can predict if this new equilibrium will be favorable or unfavorable to the cave art. 

The magazine Archaeology runs a story Who’s Killing Lascaux? http://www.savelascaux.org/Archaeology%20May%202008.pdf

2009

In January 2009, concerned scientists and citizens establish Lascaux International Scientific Thinktank. This organizations purpose is based on the belief that :

“a multidisciplinary approach involving "hard sciences" like microbiology (bacteriology, mycology, biofilms), physics, chemistry, climatology and physical-chemistry, conducted independently from the administration which remains responsible for making the decisions and implementing them, is the only way to identify the real causes of microorganism proliferation in the cave and to propose the most adapted curative measures to treat it.”

Based on analysis of data, human presence in the cave is restricted to 800 hours per year. This includes maintenance activity as well as scientific research. New restrictions require all visitors to the cave to wear sterile white coveralls, a plastic hair caps, latex gloves, and two pairs of slip on shoe covers.  The shoe covers replace the previous practice of having visitors step into an antibacterial liquid bath.  That bath was later determined to have further disturbed the cave’s microbial community.

Entering the cave is now made through two airlocks. These are designed to keep out the external humidity but still allow for the natural air currents that enter the cave through natural crack systems.

In February the French Ministry of Culture convenes an international symposium “Lascaux and Preservation Issues in Subterranean Environments”. Attended by three hundred participants from seventeen countries, the symposium brought experience elsewhere in the world in the area of cave preservation to bear on the problems of Lascaux. Participants included specialists from diverse disciplines (biology, biochemistry, botany, hydrology, climatology, geology, fluid mechanics, archaeology, anthropology, restoration and conservation).   However, by November the International Committee for the Preservation of Lascaux is publicly claiming that the French government is willfully ignoring critical conclusions of the symposium, to the detriment of Lascaux.

2010

Ten genera of bacteria are reported present in Lascaux (Ralstonia, Psudomonas, Exherichia, Achromobacter, Afipia, Ochrobactrum, Legionella, Alcaligenes, Stenotrophomonas, Symbiobacterium). No studies had been done on the bacteria of Lascaux before the benzalkonium chloride treatments, so there is no way to know what the original bacterial community was and how it has been changed by the treatments. However, there two of the bacteria in the cave (Ralstonia and Pseudomonas) are biocide resistant strains and might have evolved that resistance as a result of the treatments. Legionella is pathenogenic to humans and is the infectious agent causing Legionnaire’s disease.

Ten species of fungi are reported from Lascaux (Penicillium namyslowskii, Isaria farinose, Aspergillis versicolor, Tolypocladium cylindrosporum, richoloma saponaceum, Geomyces pannorum, Geosmithia putterillii, Engyodontium album, Kraurogymnocarpa trochleospora, Calvicipitacea sp.). Only two of these are soil bacteria.  The rest are bacteria that attack and feed on insects. The other fungi may have been brought into the cave as various small arthropods invaded it.

The rarity of Fusarium in 2010 suggests that the prolonged biocide treatments had drastically reduced the populations of this fungus.

Analysis based on samples collected between 2007 and 2009 found the fugus Scolecobasidium tshawytschae frequently isolated from the black stains. This species is known to synthesize melanin. It is usually rare in its normal environment of soil and decaying leaves. Researchers think the degradation of benzalkonium chloride by cave bacteria provided a source of nitrogen and carbon source that allowed Scolecobasidium populations to explode.

In February 2010 the French government establishes a new Scientific Council to oversee the conservation of Lascaux. However, the Lascaux International Scientific Thinktank is critical of the committee because they feel the committee composition is not appropriate for a multidisciplinary approach to the problem and is not independent of the government agencies administering the cave. This working relationship becomes more strained over time.

The fungus-eating springtail soil arthropod Folsomia candida is discovered in and around the black stains. This animal is found in caves where the cave is disturbed and normal cave dwelling arthropods are absent.  They probably entered Lascaux from leaf litter outside, attracted by the abundant food sources of the various microbial outbreaks in the cave. Folsomia candida feeds on both Scolecobasidium and Fusarium, the fungi  responsible for two of the microbial outbreaks. The fecal pellets of Folsomia contain abundant fungal spores. Thus the springtails feed on the fungus and wander around the cave walls defecating fungal spores.  This dispersal may account for the very rapid spread of the fungi in the cave.  

 2011

 In January The Ministry of Culture issues a report on the conservation status of Lascaux Cave. It briefly describes what happened at Lascaux, the major efforts underway, and makes the claim that the cave environment is stabilized and many areas show reduction or disappearance of fungal infestations. Work hours spent in the cave is kept low and the access criteria have been strengthened. Monitoring of microbial problems continue. 

The proceedings of 2009 symposium are published in 2011 in a volume which is composed of the studies presented during the sessions and full transcriptions of the debates.  Given the importance of Lascaux, the intense international interest in the cave, and the severe threats to one of the world’s great cultural resources it seems unfortunate that the report was not made freely available on line, rather than as a book to be sold.

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 Photos

1.  Lascaux Cave - Grotte de Lascaux http://www.donsmaps.com/lascaux.html

2. All others: http://www.lascaux.culture.fr

 

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Sources

1. International Committee for the Preservation of Lascaux

http://www.savelascaux.org/crisis_overview.php

http://www.savelascaux.org/timeline.php

2. Lascaux, Wikipedia http://en.wikipedia.org/wiki/Lascaux

3. Lascaux Cave - Grotte de Lascaux http://www.donsmaps.com/lascaux.html

4.  Lascaux International Scientific Thinktank http://louxorsarl.free.fr/LIST/indexLISTenglish.html

5. Time Magazine http://www.savelascaux.org/TIMEMagazine.pdf

6.  Bastian, F., Jurado, V., Novakova, A., and Alabouvette, C. 2010, The microbiology of Lascaux Cave.  Microbiology 156: 644-652.  Freely available on line at http://mic.sgmjournals.org/content/156/3/644.short?cited-by=yes&legid=mic;156/3/644

For the more technically curious reader, this review paper is a good summary of recent work on the cave’s microbiology and an excellent lead into the primary scientific literature, most of which is quite recent.  

8.  Report on the conservation status of Lascaux Cave 31st January, 2011 www.culture.gouv.fr/culture/dp/archeo/pdf/lascaux_unesco2011.pdf  Media Release by the Ministry of Culture and Communication

Translated and abridged by Don Hitchcock http://www.donsmaps.com/lascaux.html

9. Archaeology http://www.savelascaux.org/Archaeology%20May%202008.pdf

10. Preservation Interventions.  Lascaux.  http://www.lascaux.culture.fr/