Peachtree Rock - Field Trip Report by Holly Norton
The Peachtree Rock Preserve is an area of unique geological formations. Owned by the South Carolina Nature Conservancy, it is located southwest of Columbia, South Carolina in Lexington County.
On January 24, 2001 University of South Carolina geology students from the stratigraphy and Sedimentary basins class, of which I am a part, visited Peachtree Rock to study the sedimentary deposits located there, and will subsequently be discussing those deposits here.
The initial features that we saw were sandstone deposits in the most popular part of the park, where a protrusion that gives the preserve its name is located. One can see in the feature called Peachtree Rock white sand stone deposits that are laced with cross Bedded laminae of even, non-parallel lines of darker, yellow sands, of approximately middle Eocene age, according to the publication South Carolina Geology.(4) This feature also includes layers of with small flakes and blebs of clay and burrow trace fossils from the once abundaformnt marine life. (Figure 1)
Much of the silicified sandy clay surface consisted of quartz clasts, poorly sorted and ranging from well rounded to angular. There were also There was also silicified shell, casts and molds dotting the rocks consisting of marine fauna, including some bivalve shells.
Figure 1. White sand stone with darker yellow sand and brighter white clay which were initially identified as carbonate laminae but did not fizz with hydrochloric acid and could be scratched with a finger nail. Burrows are also visible.
Much of the surface was impenetrable by water, creating waterfalls on the preserve. The ground water flow also created bands of iron where it was leached from the surrounding sediments and precipitated around cracks in the rocks. (Figure 2)