TAMPA, FLORIDA—The dredging and cleaning of a spring on the Chassahowitzka River has yielded “an amazing array of artifacts that basically represent every period of human occupation in Florida,” according to archaeologist Michael Arbuthnot. Among the prehistoric artifacts found in the oxygen-free muck were a Suwannee projectile point estimated to be 10,000 years old; a bone fish hook that may have been used hunt alligators; bone pins; and a 2,000-year-old intact bowl. Later artifacts include a piece of a seventeenth-century Spanish plate; eighteenth-century Seminole pottery; a tool made of antler; and a mid-twentieth-century cap gun.