FLORIDA GEOLOGICAL SURVEY


basin divide to State Highway 50 and along State Highway 50
eastward to Clermont. The boundaries described enclose an area
of 870 square miles.



 TOPOGRAPHY

 The Green Swamp area is in the Central Highlands topographic
region as defined by Cooke (1945). The area is bordered on the
eastern side by the Lake Wales Ridge, on the southern side by the
northern termini of the Winter Haven and Lakeland Ridges, and
on the western side by the Brooksville Ridge (White, 1958, pp.
9-11). Figure 4 shows the locations of these ridges.
 Although the area is designated the Green Swamp, it is not a
continuous expanse of swamp but is a composite of many swamps
that are distributed fairly uniformly within the area. Interspersed
among the swamps are low ridges, hills, and flatlands. Several
large and many small lakes of sinkhole origin rim the southeastern
and northeastern parts of the area. The elevation of the land
surface ranges from about 200 feet above mean sea level (msl)
in the eastern part to about 75 feet in the river valleys in the
western part.
 Prominent topographic features affecting the drainage of the
eastern part of the area are the alternating low ridges and swales
that trend generally north-northwestward from the southern
boundary to the Polk-Lake County line. The ridges parallel the
major axis of the Florida Peninsula and their configuration suggests
that they were formed by subsidence and erosion along fractures
and joints. Aerial photographs of the area between U. S. Highway
27 and the Seaboard Air Line Railroad show five of these long
narrow ridges with intervening swales.
 In the western part of the Green Swamp area there is little
 evidence of the elongated ridges, and the main land-surface features
 are large swamps, flatlands, and rolling hills. There are many
 small swamps in patches and strips generally less than half a mile
 wide. Most of these swamps support good growths of cypress
 trees while in the uplands pine and scrub oak trees grow
 abundantly. The largest continuous. expanse of swampland lies
 within the valley of the Withlacoochee River and is more than a
 mile wide at places. Limestone is exposed in the western part of
 the Green Swamp area.