CANBERRA, Nov. 9 (Xinhua) -- Geologists have uncovered new evidence that dramatic sea level changes carved giant underwater canyons in South Australia's Flinders Ranges hundreds of millions of years ago, creating conditions that preserved some of Earth's earliest complex life.
Led by Australia's Adelaide University, the research shed new light on environmental changes that accompanied the rise of the Ediacaran biota, a group of soft-bodied organisms that lived more than 538 million years ago, according to a university statement released Monday.
The study examined rock formations in the Flinders Ranges, known for their rich late Ediacaran fossil deposits. These fossils preserve evidence of soft-bodied organisms that lived before the explosion of animal diversity seen later in Earth's history.
Researchers found evidence of vast, southeast-oriented canyons reaching depths of up to 280 meters and widths of more than six kilometers. They believe these features were largely formed by underwater erosion, beginning when sea levels fell significantly. Some may also have developed through erosion above sea level before becoming submerged.
As sea levels subsequently rose, seawater flooded the landscape and sediments gradually filled the canyons, helping create geological conditions for the preservation of the region's rich fossil deposits, according to the findings published in Earth and Planetary Science Letters.
The researchers said the canyons' shape and the types of sediment filling them point to powerful underwater flows capable of transporting large amounts of material. ■
