Mineral Resources On-Line Spatial Data
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Geologic units in Barnwell county, South Carolina
- Penholoway Formation (Pleistocene) at surface, covers 2 % of this area
Penholoway Formation: Similar to Cape May, broad lateral extent underlying terraces in the Carolinas; swamps and ridges on terrace surface were originally barrier islands and back bays. Superimposed on these landforms are swarms of Carolina bays.
- Neogene strata (undifferentiated) (Neogene) at surface, covers 46 % of this area
Neogene strata (undifferentiated): 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.
- Socastee Formation (Pleistocene) at surface, covers 0.5 % of this area
Socastee Formation: Low coastal formation in Carolinas like Penholoway but younger and lower in altitude.
- Alluvial Valley Swamp (Quaternary) at surface, covers 4 % of this area
Alluvial Valley Swamp: 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.
- Huber/Lisbon/Barnwell Formations, undivided (Eocene) at surface, covers 46 % of this area
Huber/Lisbon/Barnwell Formations, undivided: 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.
- Duplin Formation (Pliocene) at surface, covers 0.3 % of this area
Duplin Formation: Coastal terrace of Carolinas. Pliocene equivalent to Yorktown. Deeply weathered.
- Chenier plain and deltas of Suwannee & Chattahoochie Rivers (Holocene) at surface, covers 1 % of this area
Chenier plain and deltas of Suwannee & Chattahoochie Rivers