Why Are There ‘Star Wars’ Style Rock Structures in Australia? Researchers Finally Know the Answer

Thousands of limestone pillars rising from the sun-baked sands of this desert are much older than previously expected.

PUBLISHED 6 HOURS AGO

Majestic limestone pillars stick out of the golden sand in Australia's Pinnacles Desert. (Representative Cover Image Source: Unsplash | Tobias Keller)

Nearly 15% of Earth’s landmass is steeped in karst landscapes, which are essentially limestone structures sculpted naturally over time by climate change. When rainwater seeps into the cracks and crevices of rocks like limestone, dolomite, and gypsum, a chemical reaction happens, leaving behind dried-out remnants of the soggy rock. One such landscape nestles in Western Australia, a few miles away from the sparkling blue Indian Ocean, tucked within the picturesque Nambung National Park.

Majestic pillars stick out of the golden sand in Australia's Pinnacles Desert (Representative Image Source: Unsplash | Eddie Blair) — Majestic limestone pillars stick out of the golden sand in Australia's Pinnacles Desert (Representative Image Source: Unsplash | Eddie Blair)

Thousands of pillars rise from the golden sands, towering high and painting a surreal contrast with the sky above and sprinkles of thick green grassy bushes. People visiting this place say that the desert looks like a “Star Wars” movie set. Welcome to Pinnacles Desert, whose looming Pinnacles have long been a subject of research. The tall, weathered limestone reaches up to 3.5 meters (11.4 feet). Over the years, people have cooked up strange and creepy theories about how and when these pillars were formed.

One theory came from the Yued people from this region, according to ABC News. They called this place “Kwong kan (sandy place)” and believed that these spires were the limbs of young men who disobeyed their elders’ warnings and entered the forbidden area, getting swallowed up by the sandy monster. Another theory, explained by the National Rock Garden, says that the "Star Wars-like" Pinnacles were formed around 25,000 years ago when the shallow seas covering the area receded and left behind broken seashells. These fragments of shells fused in the lime-rich sands, which blew inland to sculpt mobile dunes. The Pinnacles could also be formed by the gradual weathering of Western Australia’s Tamala Limestone.

One theory says these pillars were formed by buried tree casts filled with calcium-rich limestone, which was exposed by wind erosion. Another theory attributes their formation to plants that accumulated a bounty of calcium carbonate over many years. While the plants died, the sands shifted away, exposing the limestone columns. The long-standing debate was finally put to rest with a recent study published in Science Advances, wherein researchers revealed that these striking stony pillars formed 100,000 years ago, the wettest interglacial period in the area’s past 500 years, when rainfall was more abundant than ever before. Lead author, Matej Lipar, concluded this after studying the iron-rich nodules studded in these chalky columns.

Majestic limestone pillars stick out of the golden sand in Australia's Pinnacles Desert (Representative Image Source: Unsplash | Chris Stenger)

“We found this period was locally the wettest in the past half-million years, distinct from other regions in Australia and far removed from Western Australia’s current Mediterranean climate. An abundance of water during this time caused the limestone to dissolve, forming the distinctive pillars of the Pinnacles and creating the ideal environment for the iron nodules to develop,” Lipar explained in a press release. His co-author, Curtin University geologist Milo Barham, likened the rock to "Swiss cheese," where the holes got so big that all that was left were the Pinnacles, per ABC News.

Majestic limestone pillars stick out of the golden sand in Australia's Pinnacles Desert (Representative Image Source: Pixabay | Tongarino)

Without investigating the iron nodules, it would have been impossible for them to determine the age of the Pinnacles. “[The iron nodules are] really small, so most people don't even notice they're there,” Lipar said. “While the limestone in the area dissolved, nodules containing iron-rich minerals formed on the Pinnacles themselves." From the results, the researchers concluded that they belonged to an extremely wet period that lasted around 102,000 years ago and dissolved the limestone, forming the Pinnacles. "These are some of the things that I guess we still need to find out. There's plenty of mystery left in the Pinnacles to explore," said Barham.

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