A strange doughnut-shaped mound in a desert in southern Australia recently made a surprise appearance in high-resolution satellite images. The odd formation, which from space resembles a big bullseye, is likely the remains of an ancient reef, made by microbes and left over from a time when a vast ocean covered the now-arid environment, new research suggests.
The new study, published July 29 in the journal Earth Surface Processes and Landforms(opens in new tab), used data from the TerraSAR-X add-on for Digital Elevation Measurement (TanDEM-X) mission, which ended in 2016 and involved a pair of Earth observation satellites that were launched and maintained by the German Aerospace Center (DLR), Germany's national space agency. Using radar data from the twin satellites, the DLR produced detailed 3D maps of the Earth's landmasses from pole to pole, according to the European Union's European Data Portal(opens in new tab).
For the new research, scientists examined DLR maps of the Nullarbor Plain, a flat, remarkably dry landscape that covers about 77,220 square miles (200,000 square kilometers) of southern Australia. A layer of limestone runs beneath the plain's surface substrate; this rock originally formed in shallow marine seagrass meadows that covered the seafloor when the plain was still submerged beneath the ocean, lead author Matej Lipar, a research associate at the Research Centre of the Slovenian Academy of Sciences and Arts (ZRC SAZU) in Ljubljana, and senior author Milo Barham, a senior lecturer at the School of Earth and Planetary Sciences at Curtin University in Perth, Australia, wrote in The Conversation(opens in new tab).
