No. 71: Sep-Oct 1990
Circular canals up to 1,450 feet in diameter and 6 feet deep have been discovered in south central Florida. Dug in the savannas and flood plains around Lake Okeechobee, the man-made circles include gaps where drainage canals extend outwards. Forty of these circular earthworks have been located by R.S. Carr. Some are as old as 450 BC; others as recent as the 16th. century. Mounds and large plazas are also part of this impressive example of Precolumbian engineering.
Carr supposes that the circular canals were fish traps, but no fish bones or other supporting evidence for this theory have appeared. Another thought is that the earthworks drained agricultural land, but no maize pollen has been found. Could they have been ceremonial sites. No one really knows. (Bower, B.; "Florida 'Circles' May Be Ancient Fisheries," Science News, 138: 6, 1990.)
Reference. Other ancient Florida canals are described in our handbook Ancient Man. Ordering details here.