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OUTCROPS IN THE VICINITY OF THE SAVANNAH RIVER SITE
wall of the pit, suggesting exposure of the underlying upper
Eocene Irwinton Member of the Dry Branch Formation. This
yellow sand pinches out a short distance to the northwest and
southeast, however, and a red sand occurs beneath it. Evidence
for the presence of the Irwinton at or near the base of
the pit are tan clay exposed in places in the floor of the excavation
and a pebble bed several tens of feet wide on the
southwest wall of the pit, possibly the flat-pebble bed which
marks the base of the Tobacco Road in places. Above this
pebble bed, the sands are red, orange, and yellow; below,
yellow sands are more conspicuous.
The fairly clean, light colored sand several feet thick at
the top is common in many places in the area. It may be
leached soil horizon, but there has been some discussion of
eolian influence.
The gray limestone which mimics an outcrop above the
Tobacco Road on the northeast wall of the pit appears to be
composed of pieces of the middle Eocene “Blue Bluff” unit
or member (Huddlestun and Hetrick, 1986, p.4). We have
found boards in the bedded clay and sands above the limestone,
and angular pebbles of metamorphic rock are mixed
with the limestone.
F. Roadcuts on the north loop of Good Hope Farms Road
(county road 1956), off Silver Bluff Road (South Carolina
highway 302); about 4 mi south of the intersection of Silver
Bluff Road and Pine Log Road (county road 87) southwest
of Aiken, South Carolina.
About 0.4 mi west of the intersection of Good Hope
Farms Road and Silver Bluff Road, the extremely poorly
sorted, cobbly facies of the Miocene Altamaha Formation is
exposed. Rounded quartz cobbles and pebbles are in a matrix
of and interbedded with red clayey sand with weathered feldspar
grains.
Down the road (to the west), cuts expose red and orange,
clayey, silty, poorly sorted medium and coarse sand of the
upper Eocene Tobacco Road Sand. Cross-beds, clay-filled
fissures, burrows, and white clay clasts occur in places. The
sand overlies bedded tan clays typical of the upper Eocene
Dry Branch Formation and a massive, tan, light gray, and
pink clay which may be the top of the “Huber Formation”.
About 0.9 mi west of the intersection of Good Hope Farms
Road and Silver Bluff Road is an outcrop of well-sorted,
very fine and fine, burrowed sand with clay laminae (see figure).
In cores and outcrops at SRS, fine and very vine sands
with clay laminae and burrows in places are common in the
middle Eocene Tinker Creek Formation, interbedded with
and updip from the middle Eocene Santee Limestone. These
fine sands overlie the Congaree and Warley Hill formations.
The fine, well-sorted sand in this outcrop is thought to be the
Tinker Creek.
The iron oxide-rich quartz pebble conglomerate and
coarse sand above the Tinker Creek sand appears to be the
same unit as the coarser sand to the east and up the road
assigned to the Tobacco Road. If it is, the Dry Branch Formation
is missing at this outcrop. Another possibility is that
the coarse nit is a facies of the Oligocene (to Miocene)
channels described by Zullo and others (1982) and Willoughby
and others (1984).
H. Outcrop on north side of Hitchcock Parkway (South
Carolina Highway 478) on the south side of Aiken, South
Carolina, about 0.8 mi west of the intersection of Hitchcock
and Pine Log Road (county road 87).
Light gray to tan, silicified, pebbly, coarse sandstone
with prominent burrows crops out on the hillside. Light gray,
yellowish and tan clay lies beneath the sand. Silicified shell
fragments that appear to be Crassostrea gigantissima occur
here. This may be the upper Eocene Dry Branch Formation,
similar to facies described by Nystrom and others (1986, p.
17). It could also be a facies of the Oligocene (to Miocene)
channels described by Zullo and others (1982) and Willoughby
and others (1984).
K. Ditch and cut at the Smile gas station in the southern corner
of the intersection of South Carolina Highway 230 and
Interstate 20, 0.3 mi southeast of Interstate 20; a few miles
northwest of North Augusta, South Carolina. The figure is
modified from Nystrom and others (1986, p. 43-47).
At the Fall Line contact, coarse, basal Coastal Plain sediments
overlie crystalline rocks, probably metavolcanics of
the Belair belt (Crickmay, 1952; Prowell and O’Conner,
1978). A Campanian palynological date has been obtained
from outcropping sediments along strike on Interstate 20
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