The iconic limestone formations standing in Western Australia’s Pinnacles Desert were formed 100,000 years ago, according to a groundbreaking new study that sheds light on past climate changes in the region.
Australia’s Aboriginal Yued people have long believed that the spires, which reach up to 5 meters high and 2 meters wide, represent the hands of ancient warriors swallowed by the sands of “Kwong-kan,” a desolate stretch that extends across 1,000 kilometres.
Now, scientists from Curtin University have provided a geological explanation for the formations, confirming their ancient origins and connection to a particularly wet period in the area’s history.
The wettest period in 500,000 years
“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,” said Matej Lipar, co-author of the study. The researchers discovered that abundant water during this time caused the dissolution of limestone, leading to the formation of the distinctive iron-rich pillars that now define the desert landscape.
Global relevance of the findings
The unique terrain of the Pinnacles Desert, marked by its towering limestone formations, is not an isolated phenomenon. Similar landscapes can be found along shorelines around the world, including in the Mediterranean, the Middle East, southern and southeastern coastal Africa, the Indian subcontinent, the Caribbean, Bermuda, and some Pacific islands. “These landscapes serve as sensitive indicators of environmental change,” Dr. Lipar noted. “However, only now do we have a method to study these formations in depth.”
Innovative geological dating method
The study employed an innovative dating technique using iron-rich nodules found within the limestone. These nodules act as “geological clocks” by trapping helium from the decay of small amounts of radioactive uranium and thorium present in the soil. “Measuring this helium provides a precise record of when the nodules formed,” explained Martin Danišík, another co-author of the study. “The dating techniques developed in this study reveal the nodules date back about 100,000 years, highlighting an exceptionally wet climate period.”
Understanding past climate shifts
Researchers hope that this new method will enable more accurate dating of climate shifts in similar landscapes around the world. This refined timeline of past environmental changes could offer valuable insights for understanding current climate dynamics. “This research not only advances scientific knowledge but also offers practical insights into climate history and environmental change, relevant to anyone concerned about our planet’s present and future,” said Milo Barham, another of the study’s authors. The study not only enhances our understanding of Australia’s ancient landscapes but also provides a new tool for examining global environmental changes over geological time.