34 FLORIDA GEOLOGICAL SURVEY—FOURTH ANNUAL REPORT. 
Hernando, Citrus and Levy Counties. Suwannee County lies chiefly 
within the limestone area. This county, which is bounded on the 
north, west and south by the Suwannee and Santa Fe Eivers, has 
undergone rapid erosion and the formations which overlaid the lime¬ 
stones have largely disintegrated, except a relatively small area 
farthest removed from the streams along the east line of the county, 
which is at present in a transition stage of degredation, as indicated 
by*the numerous lake basins formed by solution. 
The southern part of Columbia County reaches into the lime¬ 
stone formations, and in that part of the county bordering the Santa 
Fe Eiver the formations lying above the Vicksburg Limestone have 
entirely disintegrated. Farther north in the central part of the 
county, is found red clay lands, solution lake basins, and disappear¬ 
ing streams, indicating a transition stage in which the formations 
above the limestones have partly disintegrated. The extreme north¬ 
ern part of the county reaches into an area the topography of 
which has not yet been affected by solution. 
Alachua County presents much diversity in topography. Over 
most of the western part of the county adjoining the Suwannee and 
Santa Fe Eivers the Vicksburg Limestone lies near the surface. The 
hard rock phosphate belt crosses this part of the county and the 
land is well drained, as the rainfall passes almost immediately into 
the soils or disappears through the numerous sinks. The north¬ 
eastern part of the county is much higher in elevation and forms a 
level plateau 175 to 200 feet above sea. The Middle Florida Ham¬ 
mock Belt crosses the central and includes most of the southeastern 
part of the county. Numerous large shallow lakes or “prairies” are 
found in this part of the county, of which Paynes Prairie, or Alachua 
Lake, is an example. These prairies represent local areas that have 
been carried by underground solution practically to the underground 
water level. During seasons of heavy rainfall they become lakes. 
During dry seasons the water runs off through sinks, leaving the 
lake basin dry, or nearly so. 
The history of the development of the topography of Alachua 
County is not difficult to understand. The western part of the 
county has been subject to rapid and profound erosion chiefly by 
underground solution. The formations that originally lay above 
the Oligocene limestones have largely disappeared, having been dis¬ 
integrated and carried away either in solution or by mechanical 
wash. The elevated land in the northeastern part of the county 
represents the as yet uneroded part of the original plateau. The first 
effects of the erosion by underground solution are evident in this 
