2010 SOUTHEASTERN NATURALIST 9(1):105–118
Mussel Remains from Prehistoric Salt Works,
Clarke County, Alabama
Stuart W. McGregor1,* and Ashley A. Dumas2
Abstract - Archaeological research at salt springs in Clarke County, AL (Tombigbee
River drainage), documented bivalve mollusk exploitation by late prehistoric
American Indians. A total of 582 valves representing 19 species of freshwater mussels
(Unionidae) and an estuarine clam (Mactridae) from the Lower Salt Works Site
(ca. A.D. 900–1550) and 41 valve fragments representing 6 mussel species from the
Stimpson Site (ca. A.D. 1200–1550) were documented. The Lower Salt Works fauna
was dominated numerically by Fusconaia ebena and Quadrula asperata, the dominant
species reported during recent local surveys. The mussel species represented are
known from medium to large streams in sand and gravel habitats and include four federally
protected species and other species of conservation concern in Alabama. Results
offer comparative data for other archaeological and ecological studies in the region.
Freshwater mussels (Bivalvia: Unionidae) are relatively sedentary, benthic,
gill-breathing, filter-feeding organisms. They were once exploited by
prehistoric people as a source of food, adornment, and implements and, more
recently, as a commercial resource in the pearl button and cultured pearl
industries. Over the past few decades, their collective value as indicators of
water quality and as tools for evaluating long-term trends in ecosystem function
and health have become evident due to their longevity and tendency to
take up toxins (Bogan 1993, Farris and Van Hassel 2007, Naimo 1995). Mussels
also serve as an important food resource for many animals. Extensive
analysis of mussel remains recovered from 17 archaeological sites from the
lower and upper reaches of the Mississippi River Basin and the Cumberland,
Green, Scioto, and Tennessee river systems present evidence that Indians exploited
mussels for over 10,000 years (Bogan 1990). Furthermore, Stansbery
(1966) documented that as early as 6000 B.C. people settled near the musselrich
riffl es of larger streams in the Ohio River Basin. An analysis of the soft
parts (meats) of two mussel species, Actinonaias ligamentina (Lamarck)
(Mucket) and Potamilus alatus (Say) (Pink Heelsplitter), collected from 15
locations in rivers of varying size in the Midwest indicated that they yield
very few calories compared to other animals available for consumption at that
time and thus may have been a supplemental resource (Parmalee and Klippel
1974). A recent study of mussel assemblages from twenty-three sites in the
interior Middle South revealed that the consumption of freshwater mussels
1Geological Survey of Alabama, PO Box 869999, Tuscaloosa, AL 35486. 2Center for
the Study of the Black Belt, Station 45, University of West Alabama, Livingston, AL
35470. *Corresponding author - firstname.lastname@example.org.
106 Southeastern Naturalist Vol. 9, No. 1
by Southeastern Indians actually peaked during the Woodland period (ca. 700
B.C.–A.D. 1000), probably as a response to increasing population pressure
on local subsistence resources. Comparisons of the species from sites along
different portions of major rivers showed that Woodland people collected
mussels only from beds adjacent to their villages (Peacock 2002). Furthermore,
after analyzing collections from the central Tombigbee River in eastern
Mississippi, Peacock (2000) demonstrated that mussel assemblages from archaeological
contexts do not display any collection bias for certain species or
sizes. The implication is that, if a collection of mussels from an archaeological
site is large enough and obtained from a variety of contexts, it can be representative
of mussel communities in the past.
The existence of mussels is tenuous and dependent upon suitable habitat,
acceptable water quality and quantity, and appropriate host fish species for
obligate parasitic larval stages (Dillon 2000). Man’s activities across the
landscape have had profound effects on the native mussel fauna and their
hosts, especially during the past few centuries, but also from prehistoric activities
(Peacock et al. 2004). The infl uence of the more recent activities has
been well documented (for reviews see Bogan 1993, Lydeard and Mayden
1995, Neves et al. 1997). Increased international travel and commerce have
also led to the introduction of competitive exotic species such as Corbicula
fl uminea Müller (Asian Clam) and Dreissena polymorpha Pallas (Zebra
Mussel), which have had significant effects on native mussels in some areas
of North America (Strayer 1999).
The Mobile River Basin (MRB) historically supported 73 species of
mussels, including 52 in the Tombigbee River system (Williams et al. 2008).
Recent surveys indicate that more than 20 species persist in the main channel
Tombigbee River in Alabama and over 40 species persist in tributaries
of the upper Tombigbee River in Alabama and Mississippi (McGregor and
Garner 2001, 2002, 2003; McGregor and Haag 2004; McGregor et al. 1999).
Significant anthropogenic impacts to the MRB over the past 100 years, including
impoundment, eutrophication, sedimentation, pollution, and channel
modification, caused the decline in this fauna (McGregor and Haag 2004;
Williams et al. 1992, 2008). Currently, 17 species of mussels in the MRB
are recognized as endangered or threatened by the US Fish and Wildlife
Service (USFWS) (Williams et al. 2008). Additional species lacking federal
protection but of conservation concern in Alabama were given a designation
of highest conservation concern or high conservation concern by Mirarchi
(2004) based on documented or perceived trends in abundance and/or distribution.
Other species were assigned diminishing levels of conservation
concern (moderate, low, lowest conservation concern).
The recent accelerated decline of the MRB fauna has been well documented
over the past century through comparison of results of extensive
field surveys to historically collected museum material, and efforts to
reverse that trend have been enacted through legislation of protective
measures. However, there is relatively little documentation of prehistoric
2010 S.W. McGregor and A.A. Dumas 107
mussel faunas for further evaluation of possible population declines or expansions,
shifts in population centers, or potential extinction events. With
some notable exceptions, most archaeological projects emphasize other aspects
of Indian culture, while shell material encountered is often given only
cursory consideration. This is likely due, at least in part, to the complexity
of mollusk taxonomy and its changing nomenclature, which often make
identification of even fresh material problematic, compounded by loss of
identifying characters as material weathers in situ. Considerable experience
with mussel taxonomy and a reliable reference base are paramount for
reliable mussel identification.
The vast and complex mussel assemblage of the Tennessee River system,
unparalleled anywhere else in the world, has fueled interest in that fauna
for many years. Due to massive archaeological salvage efforts funded by
federal aid projects prior to closure of numerous mainstem and tributary
dams by the Tennessee Valley Authority in the mid-20th century, abundant
shell material from that region was preserved for research (e.g., Morrison
1942, Webb 1939) and extensive additional archaeological research has also
been conducted (Hughes and Parmalee 1999, Little 2000). However, that is
not the case in the MRB. It is one of the most diverse systems in terms of
freshwater mussels (Williams et al. 2008), yet displays a dearth of in-depth
prehistoric information on mussel distribution and abundance. Some notable
exceptions include Curren (1976), Peacock (1998, 2000, 2002), Peacock et
al. (2004), Quitmyer (2003), and Woodrick (1983).
Recent archaeological research in the region of salt springs in southern
Clarke County, AL (lower Tombigbee River drainage) (Fig. 1), has uncovered
evidence of the use of mussels by several distinct culture groups, from
the Late Woodland (A.D. 400–1000) to Mississippian (A.D. 1000–1550)
periods. Prehistoric Indians are known to have evaporated saline spring water
to acquire salt during drier months (Brown 1980). This practice began at
the end of the Late Woodland period (ca. A.D. 1000), probably as a means
to enhance the nutritional value of diets that relied increasingly on maize
and less on sodium-rich fish and game (Brown 1980, Dauphinée 1960). The
volume of salt production increased during the subsequent Mississippian
period in order to supply growing local populations and for long-distance
exchange with people without salt resources (Brown 1980, Dumas 2007).
In the winter of 2004–05, the junior author conducted archaeological excavations
at the Lower Salt Works (1Ck28) (A.D. 900–1550) and Stimpson
(1Ck29) (A.D. 1200–1550) sites under the auspices of the Gulf Coast Survey
(GCS), Alabama Museum of Natural History. The purpose was to gain a better
understanding of the process of salt production and the cultural identities
of those involved in it. Remains of mussels were frequently encountered
Analysis of species assemblage patterns from different occupation zones
could offer some insight into the mussel fauna available to late prehistoric
Indians in the lower Tombigbee River portion of the MRB and serve as a
108 Southeastern Naturalist Vol. 9, No. 1
benchmark for comparison to present-day species. It should be kept in mind
that excavations rarely involve the recovery of every part of a site, so the
resulting artifacts are a sample of the materials left behind. The mussels from
a particular feature, for example, probably represent only one short-term
collecting event. A better collection would include mussels from a variety of
contexts across a site, creating more of a “time-and-space-averaged” sample
(Peacock 2000). Nevertheless, inventories of any mussel collection not only
provide insight into mussel diversity and portions of dietary choices at particular
times in the distant past, but also offer comparative data to current
populations of mussels within the same watershed.
Figure 1. Locations of the Lower Salt Works and the Stimpson sites and nearby features
in relation to the Hatchetigbee anticline and the Jackson fault system, Clarke
County, AL (modified from Dumas 2007).
2010 S.W. McGregor and A.A. Dumas 109
Numerous salt springs are located in the lower Tombigbee River drainage
of the East Gulf Coastal Plain (EGCP) in southwest Alabama and are
derived from salt-bearing deposits (see Fig. 1). These formed when sea water
evaporated from the margins of the ancestral Gulf of Mexico during the Upper
Jurassic period (170–140 million years ago). This left behind tremendous
deposits of salt and other evaporite minerals that eventually became covered
by other sediments and were buried deep beneath the land surface (Landes
1960, Lefond 1969). Because salt is less dense and more plastic than
surrounding rocks, it tends to migrate toward the surface. In southwest Alabama,
upward fl ow of the Louann Salt formed the Hatchetigbee anticline, a
broad, low lying fold about 80 km in length and 30 km in width. Associated
with the anticline is the Jackson fault system, which extends north from the
Tombigbee River near the project area to 6 km northwest of Jackson (Barksdale
1929, Copeland 1968, Fenneman 1938; Fig. 1).
Connate water that originates from the vicinity of salt deposits sometimes
is pushed up through faults and fissures by pressure of the surrounding
rock and emerges as salt springs or seeps (Landes 1960, Raymond 1981).
Salt springs are common along the Hatchetigbee anticline and the Jackson
fault system. Many of them bubble up with a boiling effect due to the natural
gas that also is trapped underground. Salt water from these springs probably
lacked sufficient fl ow rates to reach the Tombigbee River and likely never
affected its salinity. However, brackish water from Mobile Bay periodically
encroaches inland as far as Jackson, Clarke County (Smith 1988). A saline
wedge was documented 48 km upstream of Mobile Bay by Robinson et al.
(1956), who found that in the lower Mobile River, when river discharge was
below a daily average of 6000 cubic feet per second (cfs), tidal conditions
were the dominant infl uence on saline intrusions, while with a daily average
discharge of over 6000 cfs, river discharge was the driving force.
The Lower Salt Works Site is located 0.5 km from the pre-lock-and-dam
channel of the Tombigbee River and 1 km from the current cut-off channel,
within the fl oodplain and at the base of a bluff, and is therefore susceptible to
fl oods during high-water events. The Stimpson Site also is 0.5 km from the
original channel and about 1.5 km from the current river. The slightly higher
elevation of Stimpson meant that it may not have fl ooded as easily. However,
it is located on the banks of Limestone Creek, a meandering third-order stream
that has impacted the landscape at the site through the deposition of alluvium.
Materials and Methods
The Lower Salt Works Site was chosen for excavation because it was
known to have been used by several different prehistoric Indian cultures for
acquiring salt (Dumas 2007). A 2.54 cm–diameter soil corer was used to conduct
probe tests into the low knolls and narrow terraces that surround the salt
springs. These areas likely were the only places that were high and fl at enough
110 Southeastern Naturalist Vol. 9, No. 1
to have supported the activities related to evaporating brine without being
threatened by potential fl ood waters. Unfortunately, later nineteenth-century
settlers and Confederate soldiers also found these locales convenient for acquiring
salt, and their activities disturbed the underlying prehistoric remains.
In an effort to find intact prehistoric strata, a 1- x 2-m excavation unit was
placed on the slope of a knoll. No salt-making activity areas were located, but
the refuse associated with such activities was found to have accumulated on
the slope. Individual layers were excavated using hand trowels, and the soil
was screened through 1.3-cm-square wire mesh. Artifacts were processed
at the laboratory of the GCS. Material from each layer was processed and
analyzed separately. The cultural affiliations of the people who created the
deposits, as well as the relative age of the deposits, were determined by examination
of the style and form of pottery. As a means to refine the chronology of
the deposits, two radiocarbon samples were obtained from wood charcoal and
sent to Beta Analytic, Inc., in Miami, FL, for analysis.
Activity at the Stimpson Site included excavation of three 2-x 2-m units
and one 2- x 5-m block of units. Mussel shells were present in small amounts
in most units, but only those from one context have been analyzed. A small
refuse pit or post mold was discovered in the profile of one unit and was
found to be entirely filled with shells.
In the absence of soft anatomy, only shell characters were available to aid
in species identifications, and were in various states of erosion. Identifications
were made using best professional judgment based on characteristics
of currently recognized taxa, and with frequent comparison to reference
specimens. Thus, it is possible that different valves with similar features,
or those representing currently unknown taxa, were misidentified. Due to
the eroded nature of the shells making positive matches of opposing valves
problematic, total numbers of valves are reported rather than total numbers
of individuals. Nomenclature follows Williams et al. (2008). All material
analyzed from both sites is curated in the GCS.
Results and Discussion
Each group that exploited the salt left behind a thick layer of refuse, consisting
primarily of broken pottery, with minor amounts of faunal material,
which, along with the lack of human remains and unarticulated (unpaired)
shells, suggests that these were not mortuary facilities, but rather food and refuse
deposits (Peacock 2002). An aggregate total of 582 valves representing
19 species of mussels (Bivalvia: Unionidae) and Rangia cuneata (Atlantic
Rangia) (Bivalvia: Mactridae) were collected from the Lower Salt Works
Site (Table 1). An additional 41 valves representing six species of mussels
were collected from the Stimpson Site (Table 2). Shells of both aquatic and
terrestrial snails (Gastropoda) were also collected and are archived at GCS,
but their abundance and frequencies were minimal and they were not analyzed.
Furthermore, it is not known if the terrestrial snails were exploited for
food or were naturally occurring. While these collections provide a glimpse
2010 S.W. McGregor and A.A. Dumas 111
Table 1. Aggregate totals of shell material collected in each layer of the Lower Salt Works Site (1Ck28) and current conservation status of each species (Mirarchi
Cultural layer (number of valves2/% total for each layer)
Taxa1 A B C D E Totals
Order Unioniformes, Family Unionidae
Amblema plicata (Say) Threeridge – P4 - 1/2.00 5/2.82 10/2.89 - 16/2.7
Ellipsaria lineolata (Rafinesque) Butterfl y – P4 - - - 1/0.29 - 1/<1.0
Elliptio arca (Conrad) Alabama Spike – P1 - - 5/2.82 1/0.29 - 6/1.0
Elliptio crassidens (Lamarck) Elephantear – P5 - - 2/1.13 5/1.45 - 7/1.2
Fusconaia cerina (Conrad) Southern Pigtoe – P5 - 1/2.00 1/0.56 7/2.02 - 9/1.5
Fusconaia ebena (I. Lea) Ebonyshell – P5 - 29/58.00 108/61.02 184/53.18 4/44.44 325/55.8
Glebula rotundata (Lamarck) Round Pearlshell – P3 - - 1/0.56 - - 1/<1.0
Lampsilis straminea (Conrad) Southern Fatmucket – P4 - - 1/0.56 4/1.16 - 5/<1.0
Lampsilis teres (Rafinesque) Yellow Sandshell – P5 - - 1/0.56 3/0.87 - 4/<1.0
Obliquaria refl exa Rafinesque Threehorn Wartyback – P5 - - 2/1.13 1/0.29 - 3/<1.0
Obovaria unicolor (I. Lea) Alabama Hickorynut – P2 - 2/4.00 1/0.56 3/0.87 - 6/1.0
Pleurobema decisum (I. Lea) Southern Clubshell – E, P2 - 1/2.00 9/5.08 20/5.78 - 30/5.2
Pleurobema perovatum (Conrad) Ovate Clubshell – E, P1 - - - 3/0.87 - 3/<1.0
Pleurobema taitianum (I. Lea) Heavy Pigtoe – E, P1 - 7/14.00 8/4.52 9/2.60 1/11.11 25/4.3
Potamilus purpuratus (Lamarck) Bleufer – P5 - - 1/0.56 - - 1/<1.0
Quadrula apiculata (Say) Southern Mapleleaf – P5 - - 4/2.26 2/0.58 1/11.11 7/1.2
Quadrula asperata (I. Lea) Alabama Orb – P5 - 8/16.00 28/15.82 82/23.70 2/22.22 120/20.6
Quadrula metanevra (Rafinesque) Monkeyface – P3 - - - 3/0.87 1/11.11 4/<1.0
Unidentified unionid valves - 73 230 221 1 525
Unidentifiable unionid fragments X X X X X X
Order Veneroida, Family Mactridae
Rangia cuneata (G.B. Sowerby) Atlantic Rangia - 21/2.00 - 8/2.31 - 9/1.6
Specimen totals per layer/% aggregate total for all layers (identifiable valves only ) - 50/8.59 177/30.41 346/59.45 9/1.55 582
1Current status of the species: E = federally listed endangered, Priority (P)1 = highest conservation concern, P2 = high conservation concern, P3 = moderate
conservation concern, P4 = low conservation concern, P5 = lowest conservation concern.
2X = present but not tallied.
112 Southeastern Naturalist Vol. 9, No. 1
of the fauna available to and selected by occupants of the sites, they cannot
be relied upon to absolutely define the mollusk fauna present at that time.
A sample in excess of 2000 valves (based on large series of samples with
40–45 species) is considered the minimum needed to find all but the rarest
of species (Bogan 1990). In his assessment of bias in archaeological mussel
assemblages, Peacock (2000) had a minimum of 2891 valves from a number
of contexts from any one site. Furthermore, most species reported herein are
associated with gravel and sand substrates in shallow habitat (easily accessible
and easy to harvest) as opposed to species more commonly associated
with soft mud or silt habitats or deep pools (not easily accessible without
specialized gear and more difficult to harvest).
At the Lower Salt Works, five intact cultural layers were examined and
are believed to represent debris associated with prehistoric salt production.
Representing the order of their deposition, Layer E is the oldest and Layer A
is the youngest (Fig. 2). Layer A had been disturbed by historical activities,
so its contents are not considered to have much cultural or chronological
value and will not be discussed further. The mussel content of Layer E is
Table 2. Aggregate totals of shell material collected at the Stimpson Site (1Ck29) and current
conservation status of each species (Mirarchi 2004).
Taxa1 # valves/% of total
Order Unioniformes, Family Unionidae
Elliptio crassidens Elephantear – P5 1/2.43
Epioblasma penita Southern Combshell – P1 1/2.43
Fusconaia cerina Southern Pigtoe – P5 1/2.43
Fusconaia ebena Ebonyshell – P5 36/87.8
Lampsilis straminea Southern Fatmucket – P4 1/2.43
Quadrula asperata Alabama Orb – P5 1/2.43
Specimen total 41
1Current status of the species: E = federally listed endangered, Priority (P)1 = highest conservation
concern, P4 = low conservation concern, P5 = lowest conservation concern.
Figure 2. Cross-section of the west wall of the 1- x 2-m excavation unit at the Lower
Salt Works Site (1Ck28), showing layers A–E (Dumas 2007).
2010 S.W. McGregor and A.A. Dumas 113
probably from a refuse pit whose associated artifacts suggest that it was
formed during the Late Woodland period, between about A.D. 600 and 900.
A charcoal sample from Layer D, also Late Woodland, yielded a calibrated
radiocarbon date of A.D. 900–1010 (Dumas 2007). Layers B and C were
deposited during salt-making activities by Mississippian people, who also
were known to collect mussels as a food source. However, they also used
crushed mussel shell as a primary tempering agent in their pottery. Based
on the decorative styles of associated artifacts, Layer C dates to about A.D.
1000–1250, while Layer B was created between about A.D. 1250 to 1400
There were only nine identifiable valves from Layer E, but they represent
species well-represented in other layers (Table 1). Layer D had the largest
number of mussel remains (n = 346; 59.5% of the aggregate total) and the
most diverse species assemblage (n = 17). While Layer C yielded a similar
number of species (n = 15), it represented only 30.4% (n = 177) of the aggregate
total. These findings, while admittedly not sufficient for meaningful
statistical analysis, follow the findings of Peacock (2002), who reported that
70% of mussel remains from 23 archaeological sites in the Tennessee and
Tombigbee river systems, totaling 203,581 valves, were found in Woodland
contexts and suggested that, based on the number of Woodland period shell
assemblages in the literature, that pattern likely holds true throughout the
Southeast. Although it is possible that some shells were used as tools or
ornamentation (Morgan 2003), their special-purpose use would not have
affected the proportions of represented species in the assemblage (Peacock
2000). The lower number of representative species in Layer B (n = 8) and
number of specimens (n = 50; 8.6% of the aggregate total) could be due to
smaller sample size yielding fewer shells. In general, these figures demonstrate
a temporal decline in shell deposition at the Lower Salt Works. This
drop may be explained, at least in part, by inferred habitation patterns at
the salt works, and not necessarily by per capita consumption. The Late
Woodland people, associated with Layer D, appear to have lived at or near
the site year round, whereas the later Mississippians occupied the area only
seasonally, based on other archaeological evidence (Dumas 2007). The sharp
decline in mussels deposited in Layer B may be a refl ection of the fact that
Mississippians at this time did not live at the salt springs but occupied the
surrounding region. They probably were able to make daily salt-making trips
and then return home for meals. Additionally, although their salt-boiling
vessels included crushed shells, the vessels were small enough to have been
made at home and then transported to the salines, thus reducing the likelihood
that mussels in Layer C were related to making pottery.
Most mussel species reported in this study are known to occupy stable
gravel and sand habitats in medium to large rivers in the MRB (Mirarchi
2004). Four federally endangered species, Epioblasma penita (Southern
Combshell), Pleurobema decisum (Southern Clubshell), Pleurobema perovatum
(Ovate Clubshell), and the Pleurobema taitianum (Heavy Pigtoe), and
114 Southeastern Naturalist Vol. 9, No. 1
two species of conservation concern in Alabama, Elliptio arca (Alabama
Spike) (highest) and Obovaria unicolor (Alabama Hickorynut) (high), were
recovered during this study but not reported from this area during recent surveys
(McGregor and Garner 2001, 2002, 2003; McGregor and Haag 2004;
McGregor et al. 1999), though Mirarchi (2004) reported that the Heavy Pigtoe
still occurs in very restricted populations in the Alabama and Tombigbee
rivers. The decline of these species is probably due to habitat alteration and
changes in water quality. It is interesting to note that while certainly far different
levels of effort were employed by prehistoric Indians (likely wading
and handpicking shallow gravel bars and shorelines or free-diving shallow
pools) as opposed to recent surveys (diving to extreme depths for extended
periods with a surface air source and a light source), the two most commonly
encountered species during this study, Fusconaia ebena (Ebonyshell)
(55.8%), and Quadrula asperata (Alabama Orb) (20.6%) (Tables 1, 2), were
also the most commonly encountered species during recent nearby investigations
(33.8% and 22.4%, respectively) (McGregor and Garner 2003).
This finding is consistent with results of Bogan (1990), who reported that
mussel communities at a given place may remain stable in terms of species
richness and abundance over periods of as long as 6000 years, as determined
from an exhaustive analysis of the mussel faunas represented in numerous
archaeological investigations in the Mississippi River Basin. It also follows
the hypothesis of Peacock (2002) that if human populations achieved the
extent surmised, then the mussel species recovered at a given archaeological
site should have been collected nearby. It is interesting also to note that
many shells collected during this study were smaller than typical adult shells
of those species collected recently (S.W. McGregor, pers. observ.). Whether
this finding is an expression of age or size selection for palatability or ease in
transport, or is a refl ection of changes in ambient temperature and concomitant
changes in food availability, or whether elevated nutrification during
recent times has accelerated shell growth in some species, is unknown.
Similar observations have been made at other archaeological sites in eastern
North America, including those reported by Matteson (1960), Peacock
(2000, 2002), Peacock and James (2002), and Quitmyer (2003). From a
statistical comparison of measurements between modern and archaeological
mussels, Peacock (2000) determined that there actually are not as many
small specimens as perceived.
The presence of the Atlantic Rangia in levels B and D is rather interesting.
Mussels from a Woodland archaeological site on the Tombigbee
River can be assumed to be locally collected and not imported from a
distant source (Bogan 1990, Peacock 2002). Rangia is a brackish water
species and only penetrates inland as far as wedges of salt water intrude
into freshwater streams and deliver its free-swimming veligers (larvae),
usually reaching farther inland during droughts (Swingle and Bland
1974). Adult Rangia can survive but cannot reproduce in freshwater. It
has been reported as far inland as the vicinity of Bottle Creek in the upper
Mobile Delta, about 40 km upstream of Mobile Bay (Quitmyer 2003,
2010 S.W. McGregor and A.A. Dumas 115
Swingle and Bland 1974). The Lower Salt Works are located about 70
river km farther inland than Bottle Creek, but Smith (1988) reported that
brackish waters from Mobile Bay occasionally encroach as far as Jackson,
20 km farther up the river, thereby providing the necessary mechanism to
deliver veligers. However, Rangia was not encountered in the vicinity
recently (McGregor and Garner 2001, 2002, 2003; McGregor and Haag
2004; McGregor et al. 1999), and no records exist from earlier historical
collections in this vicinity (Paul Hartfield, USFWS, Jackson, MS, 2008,
pers. comm.). Documented changes in sea stands and concomitant changes
in inland river levels have been implicated in altering the distribution
of many species, including mussels in inland rivers (Little 2000), and
Rangia may have periodically occupied the study area. Rangia may have
also succumbed to subtle alterations to the habitat by agricultural Mississippians
or early European settlers. It is possible, though unlikely, that
they may have been acquired through trade.
The nearby Stimpson Site has cultural components that suggest it
was contemporaneous with cultural Layer B at the Lower Salt Works.
However, the materials from Stimpson have not been fully analyzed.
The shell-filled pit or postmold feature yielded 41 valves (Table 2). Like
the Lower Salt Works, the species list from this feature was dominated by
the Ebonyshell (n = 36; 87.8%). However, valves of two species not encountered
at the Lower Salt Works Site were recovered: the Elephantear
and the Southern Combshell. The Elephantear is a widespread and abundant
species, while the Southern Combshell is a federally endangered
MRB endemic (Williams et al. 2008). The mussel-filled pit is an interesting
glimpse of a single mussel-gathering and subsequent depositional
episode at the Stimpson Site.
Summary and Recommendations
Five distinct stratigraphic layers covering about 800 years of occupation,
likely representing food and refuse deposits, were excavated at two sites in
southern Clarke County, AL, to evaluate their salt-making components. Activities
of early 19th-century settlers and Civil War era salt makers disturbed
one layer, rendering it irrelevant. Remains of 19 primarily shoal-dwelling
mussel species and 1 brackish water species were recovered from the remaining
layers and include four federally endangered species and two additional
species of conservation concern in Alabama. None of the six imperiled species
were reported from the vicinity during recent sampling efforts, likely due to
subsequent habitat alteration. Shallow water species dominated the assemblage,
possibly due to harvest bias. A consistent temporal decline in mussel
exploitation at one site, possibly due to changes in settlement patterns, was
documented. While the aggregate sample set was insufficient for meaningful
statistical analysis, the information gleaned provides a glimpse of a food
resource available to late prehistoric salt makers. Completion of the Stimpson
Site analysis and comparison to faunal remains from other archaeological
116 Southeastern Naturalist Vol. 9, No. 1
investigations in the MRB could offer a better picture of selection and exploitation
of mussels by prehistoric Indians. It is hoped that this analysis will help
to further refine distributional information on mussels in the basin, both in prehistory
Jeff Garner, Jim Williams, and Art Bogan provided taxonomic assistance. Steven
Meredith, Sandy Pursifull, Irene Burgess, Art Bogan, and two anonymous reviewers
provided helpful editorial comments on early drafts. Paul Hartfield, David Kopaska-
Merkel, Evan Peacock, Everett Smith, and Greg Waselkov provided insights from
their experiences in this area. Funding for excavation of the Stimpson Site was
provided by a grant from the National Science Foundation (NSF). Interpretation
of results of that excavation and opinions expressed regarding those results do not
necessarily refl ect those of the NSF. Funding provided by World Wildlife Fund
Southeastern Rivers and Streams Project, with the assistance of Judy Takats, supported
analysis of the mussel fauna.
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