148 marshes usually are embedded in pineland, which is flooded only during periods of exceptionally high rainfall (Figure 15). Strands and swamp hammocks are approximately 1 to 2 ft-- (30-60 cm) lower (average depth) than surrounding wet prairies, with their deepest points, excluding ponds, at least 2 ft lower than surrounding land. Although depths vary according to area, sloughs average 2 ft lower than surrounding land, and their lowest points are three or more feet lower than surrounding land. Ponds in upland areas and in wet prairies are approximately 1.5 ft (45 cm) deep at their deepest point -regardless of the area. Ponds in sloughs, strands, and swamp hammocks tend to be deeper than upland ponds. The field study pond in Corkscrew marsh is approximately 4 ft (1.2 m) deeper than the surrounding marsh bottom. Area of Wetlands According to the pond count and measurements of different vegetation communities on the ecosystems maps prepared at the Center for Wetlands, freshwater wetlands comprised approximately 62% of total land area in Hendry and Collier counties, and 26% of total land area in Lee County before any drainage of the area (circa 1900). Freshwater wetlands comprised an even greater percent of land area in Collier and Lee counties, 69% and 40% respectively, if coastal wetlands were excluded from