Meet Me in Atlantis by Mark Adams

Atlantis was laid out in a series of concentric circles. Two of land and three of water were so precisely equidistant from each other, it was almost as if theyh'd been measured out like a bull's eye. Atlantis was rich in oricalcum, a glistening metal whose preciousness was second only to gold. Fruits, flowers and domesticated grain crops flourished. And the island's lush plants supported abundant wild life, including elephants.