others have been greatly changed by drainage accompanying

agricultural or urban development.

 Two distinct physiographic regions within southwest

Florida, the Big Cypress and the sandy flatlands, were

recognized and described by John Henry Davis (1943). The

Big Cypress occurs throughout Collier County and in

southern Hendry County. The sandy flatlands cover Lee

County and all but the southern part of Hendry County and

include the area known as Devil's Garden (Craighead, 1971).

In the Big Cypress, the Tamiami formation, water-bearing -

limestone of pre-Pleistocene origin, is within a foot or

two of the surface. In the sandy flatlands, the Tamiami

formation is overlain by deposits of sand, shell, gravel,

marl, and clay 10 or more feet thick. The two regions are

connected by many shallow flow-ways that transect them.

Common to both regions are shallow depressions, or ponds,--

at all elevations, and cypress swamps, swamp hammocks,

freshwater marshes, and wet prairies.

 Figure 5 from Parker and Cooke (1944) delineates the

major geological formations and physiographic regions of

the three-county study area. Maximum elevations in the

study area are on "Immokalee Rise" (Parker and Cooke,

1944), which is the area defined as the Talbot Formation.

The highest point on the rise is 14 m above mean sea level

(MSL). Below and south of the rise, elevations slope from

about 6 m MSL to sea level, with a gradient of

approximately 3,75 cm/km. Numerous broad, shallow drainage