With Discovering the Unknown Landscape, Ann Vileisis joins a growing number of scholars who have studied the wetlands of North America. Environmental historians are beginning to pay more attention to the "unknown" sinks, playa lakes, bottoms, bogs, potholes, pocosins, bayous, kettle holes, sloughs, marshes and swamps-all of those wet places that in the 1950's came collectively to be known as wetlands-of America.