REPORT OF INVESTIGATIONS No. 42


by interpretation of electric and gamma-ray logs of some wells and
geologists' and drillers' logs of wells which are on file with the
Florida Geological Survey.

 GEOGRAPHY

 One of the most prominent topographic features in the central
part of the Florida Peninsula is Green Swamp which is an
extensive area of flatland and swampland at a relatively high
elevation. Five major drainage systems originate in or near the
Green Swamp area and flow in several directions to the sea. The
area contains the headwaters of the Oklawaha River, which flows
generally northward to become the largest tributary of the St.
Johns River; the Kissimmee and Peace Rivers that flow southward;
the Hillsborough River that flows southwestward; and the Withla-
coochee River that flows northwestward.

 LOCATION

 The Green Swamp area is in central Florida (see fig. 1) west
of and adjacent to a high sandy ridge that forms the major axis
of the peninsula. For this study the boundaries of the area were
established arbitrarily and the Green Swamp area should not be
confused with a small drainage basin that is generally known as
Green Swamp Run in the headwaters of the Big Creek watershed
in southern Lake County and northeastern Polk County. The
boundaries of the Green Swamp area, as designated for this
investigation, have been extended to encompass a much larger
area. The project area includes the southern parts of Lake and
Sumter counties, the northern part of Polk County, and the
eastern parts of Pasco and Hernando counties (see fig. 2).
 The eastern boundary of the Green Swamp area is U. S.
Highway 27, from Clermont south-southeastward to Haines City.
The southern and southwestern boundaries of the area generally
coincide with the divides separating drainage northward to the
Big Creek and Withlacoochee River basins from drainage south-
ward to the Peace and Hillsborough River basins. These boundaries
follow a meandering line westward from Haines City to a point
two miles north of Lakeland and then northwestward to Dade City.
The western boundary of the area is U. S. Highway 301 northward
from Dade City to St. Catherine. The northern boundary extends
from St. Catherine eastward along the Little Withlacoochee River