SEAC: Featured Project
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). FS Number Area Provenience Conventional Radiocarbon Age Calibrated Date 159.00001 Ridge 7 ST 37 40-50 cmbs 2510 +/- 60 BP BC 365 - BC 55 157.00001 Ridge 7 ST 36 85-90 cmbs 2360 +/- 60 BP BC 175 - AD 110 107.00001 Ridge 6 ST 33 90-97 cmbs 2210 +/- 60 BP AD 15 - AD 280 110.00001 Ridge 6 ST 35 90-100 cmbs 2210 +/- 60 BP AD 15 - AD 280 38.00001 ST 18 near ridge 6&7 ST 18 60 cmbs 110 +/- 50 BP AD 1670 - 1950 39.00001 ST 18 near ridge 6&7 ST 18 60 cmbs 2200 +/- 70 BP AD 0 - AD 330 58.00001 Egret Mound (Ridge 5) ST 31 Level 4 32 cmbs 1610 +/- 70 BP AD 265 - AD 290 AD 320 - AD 615 80.00001 Egret Mound (Ridge 5) ST 31 46-56 cmbs 1710 +/- 60 BP AD 595 - AD 800 36.00009 ST 26 ST 26 40 cmbs 1790 +/- 70 BP AD 465 - AD 730 74.00001 Ridge 3 ST 23 40-45 cmbs 1220 +/- 60 BP AD 1050 - 1295 69.00001 Ridge 3 ST 25 40, 45 cmbs 1100 +/- 60 BP AD 1200 - 1395 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. 1996 A Research Design for Archeological Investigations at De Soto National Memorial for the Regionwide Archeological Survey Program, 1997 Field Season. Manuscript on file, Southeast Archeological Center, Tallahassee, Florida. 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.