Geologic units in Sumter county, South Carolina

Duplin Formation (Pliocene) at surface, covers 30 % of this area

Coastal terrace of Carolinas. Pliocene equivalent to Yorktown. Deeply weathered.

Bear Bluff Formation (Pliocene) at surface, covers 28 % of this area

One of the older coastal terrace sequences in the Carolinas. Equivalent to Windsor Fm.

Alluvial Valley Swamp (Quaternary) at surface, covers 16 % of this area

Unconformable on all underlying units, fluvial sand and gravel at base, grading upwards into fine sands and silts, local peat. May be overrun with recent sediments from forest cutting and agriculture.

Peedee Formation - Black Creek Group, undivided (Cretaceous) at surface, covers 13 % of this area

Peedee Formation - Black Creek Group, undivided

Huber/Lisbon/Barnwell Formations, undivided (Eocene) at surface, covers 6 % of this area

Poorly to well sorted sand, clay and carbonates deposited in delta-dominated fluvial- and open-marine environments. Unit is characterized by commercial kaolin bodies in older strata from westernmost South Carolina to central Georgia. Younger strata are cyclic marine deposits which deeper water facies exposed in western Georgia. Carbonate facies are locally mined in western Georgia for agricultural lime.

Neogene strata (undifferentiated) (Neogene) at surface, covers 6 % of this area

Poorly sorted clayey sand and gravel deposited in a fluvial environment in South Carolina but becoming more fluvio-marine in Georgia. Unit is characterized by insitu weathered feldspar and an abundance of quartzite gravel and cobbles.

Waccamaw Formation (Pleistocene) at surface, covers < 0.1 % of this area

Another Carolina costalized terrace of early-middle Pleistocene age. Deeply weathered.

Peedee Formation (Cretaceous) at surface, covers < 0.1 % of this area

Peedee Formation