Geologic units in Echols county, Georgia

Pleistocene-Pliocene sands and gravels (Pleistocene-Pliocene) at surface, covers 80 % of this area

Includes, in part, Sunderland, Coharie, and Brandywine "Formations" of Cooke, 1939

Miccosukee Formation (Neogene) at surface, covers 12 % of this area

Miccosukee Formation

Hawthorn Formation (Miocene) at surface, covers 6 % of this area

Includes Marks Head Formation; Parachucia Beds (Sloan, 1905); and Alum Bluff Formation (Veatch and Stephenson, 1911).

Wicomico Shoreline Complex - marsh and lagoonal facies (Pleistocene) at surface, covers 2 % of this area

Wicomico Shoreline Complex - marsh and lagoonal facies

Hawthorn Group, Statenville Formation (Miocene) at surface, covers 0.3 % of this area

The Statenville Formation occurs at or near the surface in a limited area of Hamilton, Columbia and Baker Counties on the northeastern flank of the Ocala Platform. The formation consists of interbedded sands, clays and dolostones with common to very abundant phosphate grains. The sands predominate and are light gray to light olive gray, poorly indurated, phosphatic, fine to coarse grained with scattered gravel and with minor occurrences of fossils. Clays are yellowish gray to olive gray, poorly consolidated, variably sandy and phosphatic, and variably dolomitic. The dolostones, which occur as thin beds, are yellowish gray to light orange, poorly to well indurated, sandy, clayey and phosphatic with scattered mollusk molds and casts. Phosphate occurs in the Statenville Formation in economically important amounts. Silicified fossils and opalized claystones are found in the Statenville Formation. Permeability of these sediments is generally low, forming part of the intermediate confining unit/aquifer system.

Undifferentiated sediments (Pliocene/Pleistocene) at surface, covers < 0.1 % of this area

Undifferentiated Tertiary-Quaternary Sediments - These sediments are siliciclastics that are separated from undifferentiated Quaternary sediments solely on the basis of elevation. Based on the suggestion that the Pleistocene sea levels reached a maximum of approximately 100 feet (30 meters) msl (Colquhoun, 1969), these sediments, which occur above 100 feet (30 meters) msl, are predominantly older than Pleistocene but contain some sediments reworked during the Pleistocene. This unit may include fluvial and aeolian deposits. The undifferentiated Tertiary-Quaternary sediments occur in a band extending from the Georgia-Florida state line in Baker and Columbia Counties southward to Alachua County. These sediments are gray to blue green, unconsolidated to poorly consolidated, fine to coarse grained, clean to clayey, unfossiliferous sands, sandy clays and clays. Organic debris and disseminated organics are present in these sediments. The undifferentiated Tertiary-Quaternary sediments are part of the surficial aquifer system.