Prehistoric caves

PREHISTORIC CAVES

Dominique Genty
It is brittle, it breaks… it looks a little bit like the rind of camembert cheese, and in fact, it is soft when fresh. 
It's full of water, at least it is 2/3 water. 


 
Scientist Dominique Genty took this strange white substance from the walls of a prehistoric cave. 
Because of its milky white appearance, it has a very poetic nickname. 


 
Dominique Genty 
Moon milk in English, Mond Milch in German, lait de lune in French... it is generally known by its German name. 


 
But despite its pretty name, this white stuff can cause damage. For example, a few thousand years ago, some Mond Milch settled on the walls of a corridor in the Lascaux caves. 


 
Dominique Genty – Research Director 
Laboratoire des Sciences du Climat et de l’Environnement (Laboratory of Climate and Environmental Sciences) (CEA/CNRS/UVSQ) 
OK, so this occurred after the paintings, so it probably erased some parietal works. 
Maybe there are hidden paintings all along the white corridor of the Lascaux cave—who knows? 
On the other hand, there is also some older Mond Milch. 
That is what we find in the Chauvet cave, where over 30,000 years ago prehistoric men used their fingers to make drawings of animals such as mammoths, and it’s true that when you see drawings that were done on Mond Milch in caves, they look as if they were made just a few days ago, they're really fresh. 
So it’s something that is very stable and that probably evolves very slowly. 


 
What is this Mond Milch, with its amazing properties, actually made of? 
Mineral deposit, fungus, or bacteria? 
Mond Milch is actually a mixture of all three. 


 
Dominique Genty  
Here is an image taken with an electron microscope, and as we can see, it consists of needles of calcite, and under these calcite needles there are very fine filaments. 
Here, we have spherical shapes. 
So they could be filamentary bacteria. It could also be partly fungus... Right now, for this type of Mond Milch, we don't know. 


 
The exact composition of the white substance is still not well known. 
It could vary from one cave to another, or even from one wall to another inside a cave. 
So to find out more, the scientists took their samples to the SOLEIL synchrotron. 
With the infrared beam of the SMIS beamline, they performed a very precise analysis of the composition of samples taken from different prehistoric caves. 


 
Dominique Genty 
What interests us is to extract the organic matter from the Mond Milch, to analyse it in this way with the finest possible beam and the most stable beam possible. 
In this curve, these peaks are actually characteristic of a particular organic material. 

2nd scientist
You see here, this is interesting, because you can see it’s some material that came out of a filament. 

Dominique Genty 
On the samples we analysed, we found both traces of bacteria and traces of fungi. 


 
The results obtained will be supplemented by biological analyses. 
The scientists hope that this work will teach them more about the processes by which Mond Milch is formed. 


 
Dominique Genty 
We will try to understand how Mond Milch is formed. 
Probably thanks to physico-chemical processes, changes of temperature or pressure of the carbon dioxide in the cave, and possibly thanks to the participation of these organisms, which are either fungi or bacteria. 


 
When they have gained a better understanding of the mechanisms and conditions of development of Mond Milch, scientists will be able to deduce the environmental conditions which prevailed thousands of years ago when Mond Milch developed. 
Their work should also make it possible to improve the preservation of prehistoric paintings. 


 
Dominique Genty 
For example in a decorated cave, if tourists are allowed inside, they will bring in carbon dioxide, humidity, and heat, which will change the original conditions of the cave. 
Those changes can create conditions that are favourable to the development of Mond Milch, and if it starts to develop, it can damage the walls and therefore also the engravings, the paintings, and anything else on the walls.