This book reveals the remarkable wealth of prehistoric evidence recovered during twenty years delving into an ancient sinkhole in the remote swamps of north Florida. The authors describe the new methods of precise underwater excavations by which they survived hurricanes and worked in dark water. The deepest strata produced powerful evidence of the first Floridians, some 14,000 years ago, butchering tusks from American Mastodon in order to manufacture at least nine kinds of ivory tools. They also utilized at least a dozen other large terrestrial species of the late Ice Ages. Clever studies of stable isotopes tell that the Mastodons migrated north out of Florida into glacial terrain during the winter and spring. They also show which of the megafauna were browsers and which grazers. Digesta of the Mastodon display their rich summer diet and also contain steroids and epithelial cells. Pollen studies and sediments trace the environmental history of the region through eight millenia beginning more than 14,000 years ago.