The limestone caves and rock shelters of Indonesia’s southern Sulawesi island maintain the oldest traces of human art and storytelling, relationship again greater than 40,000 years. Paintings adorn the partitions of a minimum of 300 websites within the karst hills of Maros-Pangkep, with extra nearly actually ready to be rediscovered. But archaeologists say humanity’s oldest artwork is crumbling earlier than their very eyes.
“We have recorded fast lack of hand-sized spall flakes from these historical artwork panels over a single season (lower than 5 months),” mentioned archaeologist Rustan Lebe of Makassar’s tradition heritage division.
The perpetrator is salt. As water flows via a limestone cave system, it carries minerals from the native bedrock, and the minerals ultimately find yourself within the limestone. At the limestone’s floor, these minerals oxidize right into a case-hardened rocky crust. Nearly all the oldest rock artwork in Maros-Pangkep—like the oldest drawing in the world that depicts an precise object—is painted in pink or mulberry-purple pigment on that tough outer layer. The rock is immune to most weathering, offering a sturdy canvas for humanity’s oldest paintings.
But beneath the floor, bother is brewing. Flowing water deposits minerals within the void areas beneath the mineralized outer crust, and a few of these minerals crystallize into mineral salts. As these crystals type, develop, and shrink, they push in opposition to the outer layer of mineralized limestone. Eventually, the rocky canvas the place folks first drew photographs of their world 40,000 years in the past falls aside in hand-sized flakes.
To assist perceive the extent of the issue and ensure that salt is accountable, Griffith University archaeologist Jillian Huntley and her colleagues collected flakes from the partitions and ceilings of 11 caves within the space, together with Leang Timpuseng, dwelling of the oldest hand stencil. They discovered mineral salts like halite and calcium sulfate on the again sides of flakes from three of the websites. And all 11 websites confirmed excessive ranges of sulfur, which is a key ingredient in most of the harmful salts that fear rock-art conservators.
Exfoliation is not a brand new course of, however archaeologists and web site custodians in Maros-Pangkep say they’ve watched the method velocity up over the previous few many years. Some of the native individuals who handle and shield the rock-art websites have accomplished so for generations, they usually report “extra panel loss from exfoliation over latest many years than at another time in residing reminiscence,” wrote Huntley and her colleagues.
That’s no coincidence, based on Huntley and her colleagues.
Here’s how the method works: heavy monsoon rains drench Indonesia and the encompassing area from November to March, forsaking water in cave techniques, flooded rice fields, and brackish aquaculture ponds alongside the coast. The water carries a load of dissolved salts and their mineral substances—issues like desk salt or halite, together with gypsum, sodium sulfate, magnesium sulfate, and calcium chloride.
When the water begins to evaporate, the salt it carried stays behind as crystals, which broaden and contract together with modifications in temperature and humidity. Some geological salts, like those talked about above, can broaden as much as thrice their unique measurement when heated, they usually can put a formidable quantity of strain on the encompassing rock. The result’s just like the freeze-thaw cycles that allow water ice to crack rocks and concrete.
The complete cycle is extra energetic and extra pronounced when temperatures rise and the native climate swings from extraordinarily moist to extraordinarily dry each few months. And that is exactly the circumstances Indonesia is experiencing because the local weather will get hotter and excessive climate occasions change into extra frequent. More and extra over the previous few many years, severe monsoon flooding is adopted by intervals of intense drought.
People wrestle, rocks crack, and just a little extra of humanity’s deepest connection to itself fades away.
“We are in a race in opposition to time,” mentioned rock-art professional Adhi Agus Oktaviana of Indonesia’s National Research Center for Archaeology (ARKENAS). “Our groups proceed to survey the realm, discovering new artworks yearly. Almost with out exception, the work are exfoliating and in superior levels of decay.”
