BRIEF REVIEW OF THE EOCENE SANTEE LIMESTONE IN THE LAKE MARION AREA, CENTRAL SOUTH CAROLINA

The zonal oyster Cubitostrea sellaeformis occurs at the Santee Limestone type locality of Eutaw Springs, Orangeburg County, South Carolina. A rich biota is associated. The Santee is middle middle Eocene. The Santee unconformably overlies the middle middle Eocene Warley Hill Formation in outcrop at Cave Hall, Calhoun County and in the subsurface at Eutaw Springs. The Warley Hill is quartzose and glauconitic updip. Downdip, it grades to glauconitic lime mudstone and soft, bryozoan-mollusk-echinoid packstone. At Wilsons Landing, Berkeley County, the lower Warley Hill is glauconitic lime mud, and the upper Warley Hill is bryozoan-mollusk-echinoid packstone. The Warley Hill – Santee contact has been exposed in the Martin Marietta Orangeburg and former Berkeley quarries. The Warley Hill – Santee occurs in the subsurface in east Orangeburg County, east Calhoun County, south Clarendon County, and northwest Berkeley County. In a complete section, the Santee unconformably underlies upper middle Eocene limestone. The contact is at 189.4 ft depth in the USGS Pregnall no. 1 core in Dorchester County (Geisler and others, 2005). Limestones that show the oldest upper Santee contact are not exposed. The proposed top of the sellaeformis zone (= Santee) in the former Berkeley quarry is not now exposed, is doubtful, and investigation of cores is needed. At the Orangeburg and former Berkeley quarries, the Santee Limestone includes three or four alternating zones of hard and soft, light- to medium-gray, shelly to muddy limestone. At Eutaw Springs, similar lithologies occur in more numerous and thinner zones. From Eutaw Springs updip to Halfway Swamp, the Santee grades to softer, partly shelly limestone. Lateral changes in lithologies seem gradational. Four Santee members have been proposed. Eocene limestone in the Giant Cement quarry near Harleyville, and formerly assigned as Santee, is younger than the Santee Limestone. Pinchouts of the upper middle Eocene limestone and the upper Eocene Harleyville Formation, between the USGS Pregnall corehole and Eutaw Springs at Santee River, are not determined. This review benefited from auger holes in support of STATEMAP maps of Saint Paul, Elloree, Lone Star, Fort Motte, Pinewood, Summerton, and Jordan quadrangles and from five SCDNR cores at Eutaw Springs, at Santee State Park, and in Jordan quadrangle.