FLORIDA GEOLOGICAL SURVEY The carbonate sediments of the Torreya Formation are white to light olive gray, poorly- indurated, variably sandy and clayey limestones. The limestone (mudstone and wackestone) often contains molds and casts of mollusks. The Torreya Formation overlies the FAS and forms part of the intermediate aquifer system/intermediate confining unit (IAS/ICU) (Southeastern Geological Society Ad Hoc Committee on Florida Hydrostratigraphic Unit Definition, 1986). The top of the Torreya Formation ranges from 145 feet (44.2 meters) above MSL in W- 10713 (cross section A-A' on OFMS 99-02) to approximately 45 feet (13.7 meters) above MSL in the vicinity of where it pinches out on the Aucilla River in the Lamont SE quadrangle (see OFMS 99-02). The unit ranges from less than 5 feet (1.5 meters) in the vicinity of the Aucilla River up to 155 feet (47.2 meters) thick in W-6558 in the Greenville quadrangle (see Appendix A for well location). Tertiary-Quaternary Systems Pliocene Series Miccosukee Formation The Pliocene Miccosukee Formation (Tmc), named by Hendry and Yon (1967), is a prodeltaic siliciclastic unit composed of grayish-orange to grayish-red, mottled, poorly- to moderately-indurated, interbedded clay, sand and gravel of variable coarseness and admixtures. The unit has limited distribution in the eastern panhandle of Florida and occurs from central Gadsden County (west of the study area) to eastern Madison County (Scott et al., 2001). The top of the unit, present predominantly within the northwestern and northeastern corners of the map area, with minor outliers in the north-central portion of the map area, ranges from approximately 100 feet (30.5 meters) above MSL to approximately 230 feet (70.1 meters) above MSL in field exposures (see OFMS 99-01 and OFMS 99-02). The Miccosukee Formation ranges from a few feet thick to approximately 130 feet (39.6 meters) in thickness in this area. The unit is relatively impermeable due to its high clay content, but is considered to be part of the surficial aquifer system (SAS) (Southeastern Geological Society Ad Hoc Committee on Florida Hydrostratigraphic Unit Definition, 1986). Pleistocene Series Undifferentiated Quaternary Undifferentiated Quaternary sediments (Qu) lie unconformably on the Oligocene Suwannee Limestone (Ts), the Miocene St. Marks Formation (Tsmk) and the Miocene Torreya Formation (Tht) throughout much of the middle portion of the study area. These sediments, which generally consist of sandy clays and clayey sands, often include weathered and silicified boulders of the Suwannee Limestone ("float"). The undifferentiated Quaternary sediments (Qu) are part of the SAS (Southeastern Geological Society Ad Hoc Committee on Florida Hydrostratigraphic Unit Definition, 1986).