Dr. Peter Doran's group recently published a study investigating the moat history of Lake Bonney, located in the McMurdo Dry Valleys. Their paper titled, Constraining the recent history of the perennially ice-covered Lake Bonney, East Antarctica using He, Kr and Xe concentrations, suggests open moats have only operated on Lake Bonney for two-three centuries in the last millennium. Their results further indicate a history of ice cover for at least five millennia and that lake levels have been rising in the last century.