Download Guidebook as .pdf (1.8 Mb) - Carolina Geological Society

PAUL G. NYSTROM, JR.
GMP-13
Description
This hole (figure 3) was drilled on Hickson Mill Road in
the floodplain of Tinker Creek approximately 1.5 miles west
of Kennedy’s Pond. The collar elevation was 205 ft. The Qal
was is only 12 ft thick at this site. The interval from 0 to 7 ft
is black, wet, gooey ooze with bits of wood and other plant
matter. From 7 to 11.5 ft there is brown peat. Sample GMP-
13 was collected from the 7 to 10 ft interval. From 11.5 to 12
ft there is a pebbly grit which marks the base of the Qal.
Interpretation
There is only one fining upward sequence in this alluvial
section. The radiocarbon date of 11,110+50 yr. B.P. is the
age for deposition of the basal part of the floodplain
sequence intersected in this hole. Sediments in the upper few
feet of the floodplain are, of course, younger since some
plant matter is added to the surface each year. The radiocarbon
date indicates that this part of the Tinker Creek valle
has been relatively stable with virtually no floodplain incision
and very little deposition in the last 11,110 years.
SUMMARY AND CONCLUSIONS
The middle Wisconsinan radiocarbon dates for terrace
sediments adjacent to Upper Three Runs (GMP-3; table 1)
and Tinker Creek (GMP-12-1, GMP-12-2 and GMP-12-3;
table 1) pre-date by 16,000 to 20,000 years the glacial maximum
and corresponding low sea level stand approximately
18,000 years ago. The late Wisconsinan date of 11,110+50
yr. B.P. for sediments in the floodplain of Tinker Creek is
considerable older than Stevenson’s (1982) oldest date of
4,010+130 yr. B.P. from the Savannah River floodplain. This
suggests active deposition in the Savannah River floodplain
has occurred more recently than in the headwater area of
Tinker Creek. Therefore, aggradation of the valley floor similar
to that suggested for the Savannah during the Holocene
sea level rise (Stevenson, 1982) did not extend to upper
Tinker Creek.
Brooks and Colquhoun (1991) concluded the age of the
youngest terrace adjacent to the active Savannah River floodplain
is approximately 10,000 years based on artifacts.
Whereas Hanson and Bullard (1992) proposed an age of
200,000 to 350,000 years for the same terrace based on characteristics
of the soil profile. Neither of these views correlate
well with the middle Wisconsinan radiocarbon dates for terrace
sediments along Upper Three Runs and Tinker Creek.
This points to the need for more work on the geomorphology
of the SRS. Additional dating of terrace and floodplain sediments
will lead to a more complete understanding of the evolution
of the landscape. Also, pollen analyses of peat will
contribute to a sharper assessment of the climatic variations
which occurred during the late Cenozoic.
ACKNOWLEDGEMENTS
I thank Kathryn Hanson and Tom Bullard of Geomatrix,
Inc., for sharing the radiocarbon dates of the peat. Also, Tom
Bullard and S.A. Schumm generously provided literature
unfamiliar to me for which I express my appreciation.
REFERENCES CITED
Brooks, M.J. and D.J. Colquhoun. 1991. Late Pleistocene Holocene
depositional change in the Coastal Plain of the Savannah River
Valley: A geoarchaeological perspective: Early Georgia v. 19,
no. 2, pp. 1-20.
Colquhoun, D.J. 1981. Variation in sea level on the South Carolina
Coastal Plain In Colquhoun, D.J. ed. Variation in sea level on
the South Carolina Coastal Plain. I.G. C.P. #61. Pp. 1-44.
Dowsett, H.J., and T.M. Cronin. 1990. High eustatic sea level during
the middle Pliocene: Evidence from the U.S. Atlantic
Coastal Plain: Geology v. 18, pp.435-438.
Hanson, K.L. and T.E. Bullard. 1992. Quaternary and neotectonic
program field trip guidebook. ESAC Meeting. Augusta, Georgia.
Newell, W.L., M.J. Pavich, D.C. Prowell, and H.W. Markewich.
1980. Surficial deposits, weathering processes, and evolution of
an inner Coastal Plain landscape, Augusta, Georgia. In Frey,
R.W. ed., Excursions in Southeastern Geology, v.2, Geological
Society of America 1980 Annual Meeting, Atlanta, Georgia:
Falls Church, Virginia, American Geological Institute, pp. 527-
524.
Nystrom, P.G., Jr. 1990. The original course of the Savannah River,
South Carolina Upper Coastal Plain: Geological Society of
America Abstracts with Programs, v. 22, no. 4, p. 53.
Nystrom, P.G., Jr. and R.H. Willoughby. 1992. The upland unit in
the Savannah River Site: distribution, lithology, depositional
environment and age: Geological Society of America Abstracts
with Programs, v. 24, no. 2, p. 56.
Nystrom, P.G., Jr., R.H. Willoughby, and L.E. Kite. 1986. Cretaceous
Tertiary stratigraphy of the upper edge of the Coastal
Plain between North Augusta and Lexington, South Carolina:
Carolina Geological Society Field Trip Guidebook 1986,
Columbia, South Carolina, 82 p., 1 sheet, scale 1:100,000.
Prowell, D.C. and S.F. Obermeier. 1991. Evidence of Cenozoic tectonism,
In. J.W. Horton, Jr. and V.A. Zullo, eds., The Geology
of the Carolinas, Carolina Geological Society Fiftieth Anniversary
Volume: Knoxville, University of Tennessee Press, pp.
309-318.
Stevenson, A.E. 1982. Geomorphic History of a Portion of the
Savannah River Floodplain, Barnwell County, South Carolina.
M.S. Thesis, Department of Geological Sciences, University of
South Carolina, Columbia, S.C.
Stone, P.A. and J.G. Brown. 1981. The pollen record of Pleistocene
and Holocene paleoenvironmental conditions in southeastern
United States, In Colquhoun, D.J., ed., Variation in sea level on
the South Carolina Coastal Plain. I.G.C.P. #61 PP. 156-181.
70