Mount Gambier is a maar complex in South Australia associated with the Newer Volcanics Province. It contains four lake-filled maars called Blue Lake, Valley Lake, Leg of Mutton Lake, and Brownes Lake. It is one of Australia's youngest volcanoes, but estimates of the age have ranged from over 28,000 to less than 4,300.[2] The most recent estimate, based on radiocarbon dating of plant fibers in the main crater (Blue Lake) suggests an eruption a little before 6000 years ago.[3]