De Soto Volunteers: 300 BC
On January 13, 1997, a crew from the Southeast
Archeological Center (Dr. Guy Prentice, Principal Investigator, Margo
Schwadron, field director, Elizabeth de Grummond and Lou Groh) began
a three week archeological survey and testing project at De
Soto National Memorial. Hundreds of people volunteered to participate
in the archeological project.
The project, part of the Center's Regionwide Archeological Survey Program,
was designed to locate, identify and evaluate archeological resources
within the park (Schwadron 1996). Several particular research questions
and survey goals were targeted: 1) testing of shell ridge features in
the mangrove swamp to determine their nature and to determine if they
were prehistoric or natural; 2) testing of the Marker Mound to determine
if the mound was prehistoric or modern in construction; 3) testing of
a "mound" located on the west boundary of the park to determine
its nature; 4) testing in the area of the Tabby Ruins for possible features
associated with the William Shaw occupation or other historic occupations;
and 5) mapping of the shell ridges with GPS.
The mapping of the shell ridges was conducted with a Trimble Pro-XL sub-meter
accuracy global positioning system (GPS). The use of GPS to map the shell
ridges in the mangrove swamp was successful, and required no cutting of
vegetation. A total of seven ridges were identified and mapped in the
field, and the post-processing of the data in GIS and Autocad produced
a plan-view map of the shell ridges.
Each ridge was archeologically tested with 50-by-50 cm shovel tests.
All material removed from each test was screened in ¼" hardware mesh
screen. All artifacts and ecofacts recovered from the test were bagged
and labeled with appropriate provenience information and later transported
to the Southeast Archeological Center for analysis. Shell samples and
radiocarbon samples were also taken from every shovel test.
Testing of the shell ridges determined that all of the ridges consist
of solid, prehistoric shell midden, containing prehistoric pottery, shell
tools, food remains (deer, turtle, bird, fish, shellfish), and lithics.
Eleven radiocarbon dates from the shell ridges were submitted to Beta-Analytic,
with excellent results (Table 1). The suite of radiocarbon dates indicates
that the shell ridges were occupied chronologically at distinct and separate
times, over the course of roughly 1,800 years. The farthest inland ridges
are the earliest, dating from BC 365 to AD 110, and the closest ridge
to the cove dates from AD 1050 to AD 1395. A preliminary hypothesis is
that the shell ridges developed along a series of successive shorelines
that have been slowly building up over time through a gradual coastal
geomorphological process called progradation. The shell ridges are midden
accumulations that resulted from the collection and processing of marine
resources for food and tool use in human occupation areas that were located
along the shoreline.
Analysis of the artifacts from each ridge is currently underway to determine
if changes occur through time in artifact forms and frequencies (pottery,
shell tools, lithics) and in the dietary patterns and food resources.
A detailed analysis and discussion of the site formation process of the
shell ridges will be available in the final report for the project and
in a master's degree thesis (Schwadron 1997).
Table 1. Radiocarbon Date Results from the Shell Ridges.
A long history of shell mining and filling episodes
at the park created a complicated archeological problem, and it remained
unclear whether the Marker Mound was prehistoric or modern in construction
prior to the recent investigations. Since the Marker Mound had never been
examined archeologically, a 1½ by 1 meter excavation unit was placed on
the south slope of the mound.
Excavation of the mound revealed a series of modern filling episodes
in the upper portions of the mound. Underneath the modern fill zones,
starting at 85 cm below the present ground surface, are primary, intact
strata, approximately 1 meter thick. At 160 cm, the base of the mound
was located, situated on a sterile zone composed of finely crushed shell
fragments and coarse beach sand. Three shell radiocarbon samples were
taken from the bottom three zones of the mound, suggesting that the base
of the Marker Mound was constructed during the Early Manasota Period around
AD 15 to AD 345.
View
archeological profile plan map [378K]
All pottery recovered from the Marker Mound was Sand-Tempered Plain,
and most rim and lip forms appear to be incurving, rounded and/or chamfered.
A detailed analysis is currently underway to determine if changes occur
in the formal and technical variability of pottery throughout the mound.
Preservation at the site was excellent, and faunal artifacts recovered
from the intact strata of the Marker Mound included worked bone and bone
pins, and a dozen fish species, (mostly catfish, mullet and drums), sharks
and rays, birds, and mammals. A variety of shell tools were recovered
from the Marker Mound, most commonly small Fighting Conch hammers, and
a variety of gastropod columella tools, including hammers and cutting
edged types. Southern Quahog Clam choppers and anvils were also common,
with the vast majority consisting of left valves.
The Remnant Mound, a large shell mound located along the beach at the
west boundary of the park, exhibits several large borrow holes and recent
looter's holes on the east side of the mound, but a substantial portion
of the remaining mound appears to be undisturbed. A single 1 by 2 meter
excavation unit was placed on the south slope of the mound in an undisturbed
area of the mound. Excavation of the unit revealed four distinct stratigraphic
midden zones, reaching to a depth of 170 cm. Water was encountered at
155 cm, and a sump pump was used to excavate below the present water table.
A suite of radiocarbon dates were submitted for each zone of the Remnant
Mound, providing calibrated calendar dates ranging from 45 BC to AD 895.
The base of the mound was encountered at a depth of 170 cm, and was situated
in a peat and muck zone with remnants of mangrove prop roots present.
The presence of peat and the two radiocarbon dates from the base of the
mound suggest that the first level of the mound was built in a wet, mangrove
environment during the early Manasota period, around 45 BC to AD 250.
No structural evidence was found in the excavation unit, but at 140 cm,
a fire pit feature was encountered. The feature consisted of gray and
white ash and sand with highly burned shell and faunal material, with
some pottery and worked bone fragments. The fire pit measured 20 cm in
thickness, and was completely enclosed within zone C, which is radiocarbon
dated from AD 120 to 410.
Preservation was excellent within the mound, and many artifacts and faunal
remains were recovered, including a drilled shell bead, and worked bone
implements. A preliminary faunal analysis of the ¼ inch screen material
has so far identified about a ten species of fish (including puffers,
sheepshead, and Jacks), sharks and rays, mammals, rodents, and deer. Most
prevalent throughout all zones of the mound were shell tools, including
many small Fighting Conch hammers, possibly used to tenderize shellfish
meat. Columella hammers were another common tool type, and some columella
fragments from cutting-edged tools, possibly used for wood-working, were
also present.
Hundreds of Sand-Tempered Plain pottery sherds were recovered throughout
the Remnant Mound, along with one Limestone Tempered and one Dunns Creek
Red sherd. Analysis of the rim and lip forms, as well as vessel thickness,
is underway to determine if changes in forms occur through time.
Shovel testing of the Tabby Ruins area was conducted on a 20 meter interval
grid, with a total of 25 50-by-50 cm shovel tests (Figure 4). Testing
resulted in the recovery of many historic artifacts, including historic
ceramics, glass, a bottle, a wooden toothbrush, pipe stem fragments and
machine-cut nails. No features or evidence of other structures were encountered,
and the artifact assemblage is typical of and indicates a domestic occupation
dating to the time around William Shaw's occupation of the site.
Though only specific areas of the park were investigated (the shell ridges,
Marker Mound, Remnant Mound and the Tabby Ruins area), no evidence of
De soto, Spanish, fishing-rancho or Civil War period sites or artifacts
were encountered, with one exception. One piece of glazed coarse-earthenware
pottery was recovered from the very top of a shovel test on Midden 26
in the mangrove swamp. The pottery may be Spanish in origin, probably
from a late Spanish fishing rancho.
Summary
This project would not have been as successful without the wonderful
support and assistance from our volunteers and the park. We enjoyed working
with our volunteers, and would like to thank everyone who became involved
with this project.
References Cited
Schwadron, M. 1997 An Archeological Investigation of Shell Ridges at Shaw's Point (8Ma7),
De Soto National Memorial, Bradenton, Florida. Unpublished master's thesis,
Department of Anthropology, Florida State University.
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