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Limestone caves and stone shelters on the southern island of Sulawesi in Indonesia the oldest traces of human art and storytelling, Which is over 40,000 years old. The paintings adorn the walls of at least 300 sites on the karst hills of Maros-Pangkep, and they are almost certain to be waiting to be restored. Archaeologists say that the oldest art of mankind is falling before their eyes.
“We have recorded that hand-made flakes the size of these ancient art panels are rapidly lost in a single season (less than five months),” said archaeologist Rustan Lebe of the Makassar cultural heritage department.
The culprit is salt. When water passes through a system of limestone caves, it carries minerals from the local rock and the minerals eventually end up in the limestone. On the surface of the limestone, these minerals are oxidized in a hardened rocky crust. Like almost all of Maros-Pangkep’s oldest rock art the oldest drawing in the world which depicts a real object – in that hard outer layer is painted red or more purple. The rock is weather-resistant, providing a durable canvas for humanity’s oldest works of art.
But problems are emerging under the skin. The spilled water stores the minerals in empty spaces under the outer crust, and some of these minerals crystallize into mineral salts. As these crystals form, grow, and shrink, they push against the outer layer of mineralized limestone. Eventually, the rocky fabric that people drew images of their world from 40,000 years ago falls into hand-sized flakes.
To help understand the extent of the problem and confirm that the salt is to blame, Griffith University archaeologist Jillian Huntley and her colleagues collected flakes on the walls and ceilings of 11 nearby caves, including Leang Timpuseng, home of the oldest manual template. Three of the sites found mineral salts such as halite and calcium sulfate on the back of the skin. And 11 sites showed high levels of sulfur, which is a key ingredient in many of the destructive salts that rock art conservatives are concerned about.
Exfoliation is not a new process, but Maros-Pangkep archaeologists and site guards say they have seen the process accelerate in recent decades. Some of the local people who manage and protect the rock sites have done so for generations, and “the loss of panels caused by exfoliation in recent decades has been greater than at any other time in memory,” Huntley and colleagues wrote.
That’s no coincidence, according to Huntley and his colleagues.
Here’s how the process works: monsoon rains soak Indonesia and the surrounding region from November to March, with water in cave systems, flooded rice fields and saltwater ponds in aquaculture along the coast. Water carries a load of dissolved salt and its mineral components — table salt or halite, such as gypsum, sodium sulfate, magnesium sulfate, and calcium chloride.
When the water begins to evaporate, the salt it carries is left behind as a crystal, which expands and shrinks with changes in temperature and humidity. Some geological salts, such as those mentioned above, can triple their original size when heated, and can put tremendous pressure on the surrounding rock. The result is similar to the freezing-thaw cycles that allow water ice to crack rocks and concrete.
The whole cycle is more active and noticeable when temperatures rise and the local weather goes from very humid to dry every month. That is precisely the conditions in which Indonesia is experiencing as the climate warms and extreme weather events become more frequent. More and more in recent decades, severe monsoon floods then there are periods of severe drought.
People struggle, the rocks crack and the deepest connection that humanity has with itself disappears.
“We are in a race against time,” said rock art expert Adhi Agus Oktaviana of the Indonesian National Archaeological Research Center (ARKENAS). “Our teams continue to explore the area, finding new artwork every year. Almost without exception, the paintings are exfoliating and are in the advanced stages of decline.”
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