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OUTLINE OF STRATIGRAPHY AT THE SAVANNAH RIVER SITE
facies becoming dominant in the southeastern part.
UPPER PALEOCENE
Lang Syne Formation
Lithology and stratigraphic terminology
At SRS the Lang Syne typically consists of dark gray
and black, lignitic clays and poorly and moderately sorted,
micaceous, lignitic, silty and clayey quartz sands and pebbly
sands interbedded with dark gray clays. Iron sulfides are
common in the darker parts of the section. Both sands and
clays are glauconitic in places, especially in the southeastern
part of the Site. The basal unit is a green sand in places. The
clays tend to be fissile and contain micaceous silt and fine
sand laminae, often glauconitic. Cristobalite is common in
some cores. Deposits composed of yellow, orange, tan, moderately
to poorly sorted, micaceous quartz sands are comm
in the northwestern part of SRS, with darker, poorly sorted,
micaceous facies becoming dominant to the southeast. In
some wells, clean, moderately to well-sorted sands occur
near the top of the unit.
Basal sands which are glauconitic in places lie on dark
clays or dark, moderately and poorly sorted sands of the
Sawdust Landing. A pebbly zone is common at the contact.
In general the Lang Syne contains more glauconite, muscovite,
lignite, and iron sulfide than the Sawdust Landing, and
the clay beds are much thicker. It tends to be darker and to
contain less feldspar. It is difficult to pick the contact where
the basal sand is not glauconitic. The Lang Syne appears to
be sporadic in the northwestern part of SRS and is about 80
ft thick near the southeastern boundary. It is somewhat calcareous
in the deep well near Allendale, South Carolina.
The type locality of the Lang Syne is in central eastern
South Carolina (Sloan, 1908; Padgett, 1980; Colquhoun and
others, 1983; Howell, 1985; Muthig and Colquhoun, 1988;
Colquhoun and Muthig, 1991; Nystrom and others, 1991).
At SRS, it appears to be the upper part of the “Ellenton Formation”
of Siple (1967) as used by Prowell and others
(1985b) and Logan and Euler (1989); of the “Black Mingo
Formation” as used by Oldham (1981); of the “Ellenton Formation”
and the “Rhems Formation” as used by Colquhoun
and others (1983); of the “Ellenton member of the Rhems
Formation” as used by Steele (1985); and of the “Rhems Formation”
as used by McClelland (1987). The term “Lang
Syne” is applied here rather than “Rhems”, because our
palynological data indicate that the Lang Syne (upper
“Ellenton”) strata at SRS and vicinity are late Paleocene
(Thanetian or Selandian) rather than early Paleocene
(Danian). The Rhems has been dated as Danian (Van Nuiewenhuise
and Colquhoun, 1982). The Lang Syne at SRS is
the upper part of unit P1 of Prowell and others (1985a).
Paleontology, age, and correlation
The Lang Syne has yielded numerous palynoligical
assemblages which indicate an assignment to calcareous
nannoplankton zones NP 4-8 or 5-8. A nannofossil assemblage
from the Lang Syne in the deep Allendale well was
given a late Paleocene age by Laws (1992, p. 112). Frederiksen
(1991) dated several samples from the “Ellenton” at SRS
as late Paleocene. Muthig and Colquhoun (1988) assigned
the Lang Syne in the type area to the lower Paleocene, but
Nystrom and others (1991) believed it to be upper Paleocene,
citing age determinations from dinoflagellates, calcareous
nannofossils, and mollusks. It probably correlates with the
Naheola and Nanafalia formations of the Gulf Coastal Plain
(upper Midwayan and lower Sabinian; lower and middle
Thanetian or Selandian).
Environment
Upper delta plain deposits composed of light-colored,
moderately to poorly sorted, micaceous quartz sands are
common in the northwestern part of SRS, with darker, poorly
sorted, micaceous lower delta plain and prodelta facies
becoming dominant in the southeastern part. Glauconitic
sands probably represent transgressive deposits.
Snapp Formation—A New Formation
Lithology and stratigraphic terminology
The type section of the Snapp Formation, composed of
quartz sand and interbedded kaolinitic clay, is described in
the appendix from core from SRS well P 22TA in southern
Barnwell County, South Carolina. Typically, the sediments
are light gray, tan, orange, and yellow, silty, micaceous,
medium to coarse quartz sands and pebbly sands interbedded
with kaolinitic clays. The micaceous sands have a powdery
appearance in some wells. Sorting in the sands is generally
poor, but well-sorted sands are present. Dark, micaceous, lignitic
sands also occur. The clays are oxidized in some places
but dark in others.
In most wells basal, light colored, micaceous Snapp
sands lie on dark clays, glauconitic in places, of the Lang
Syne. Snapp sands are usually lighter in color than Lang
Syne sands, and the unit contains less lignite, iron sulfide,
and glauconite. In the middle of SRS, a few cores contain
sands of both formations which are better sorted and lighter
in color than is typical, making it difficult to pick a contact.
The sharpness of the contact in most cores suggests and
unconformity, but the time gap may be small.
The Snapp is well developed in the southeastern part of
SRS, where there are two fining-upward sequences. Only
one sequence occurs in the center of the Site, and the Snapp
appears to pinch out updip in the vicinity of Upper Three
Runs. It is about 70 ft thick near the southeastern boundary
of SRS and is present downdip in well C 10 near Allendale,
South Carolina. A glauconitic sand occurs in this part of the
section in well C 6 near Barnwell.
The Snapp has been referred to in the study area as
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