Southeastern Section–56th Annual Meeting (29–30 March 2007)

Paper No. 4
Presentation Time: 2:40 PM

WHERE IS THE GREAT FALLS OF THE CATAWBA? GEOLOGY - ARCHEOLOGY AND HISTORY


PRIVETT, Donald R., S.T.A.R. Environmental, 1 Circle Street, Great Falls, SC 29055, privett@InfoAve.net

The Great Falls of the Catawba (GFC) is located the Piedmont Province, near the boundary between the Carolina Slate belt and The Charlotte belt. The Piedmont is a gentle rolling surface where larger tributaries streams occur in steep sloping entrenched valleys.

The Great Falls Metagranite is the most common rock, is a nearly circular, 40 square mile, 543 +/- 63 million year old (Cambrian or late Pre-Cambrian), metamorphosed granite composed of quartz, feldspar and mica; probably a crystallized magma chamber, intrudes metamorphic and igneous rocks and is cut by north - northeast striking mafic dikes.

The Catawba River heads east of the Blue Ridge escarpment on Chestnut Ridge near Old Fort, North Carolina. It flows into a broad valley for 120 km then makes two angular turns to flow south into South Carolina.

Near Great Falls, SC the river has cut a deep channel through saprolite exposing an extensive boulder field and bedrock. Before the Catawba River was dammed, it dropped more than 22 meters in five km in a series of rapids and waterfalls.

Duke Energy diverted the River in two areas. Riverbeds are exposed for approximately 3600 (short) and 10,000 (long) feet below spillways. The GFC is mostly covered by a concrete dam, only the lower part is exposed. Abundant potholes, 25 - 40-cm. wide and 30 cm. deep occur in rocks at the base of the dam. Bedrock is also fluted and has been polished smooth by water flow and suspended sediments.

Rocks exposed in the long bypass display evidence for rapids and cascades; suggesting that GFC was located in/along it. Most geomorphic and geologic evidence suggests the GFC is behind the dam of short diversion also an 1879 Corps of Engineer map locates it there and notes a fall of 50 feet.