Archaeological Investigation

Results of 1999 Archaeological Investigation
As described above, the remains of the Emeryville Shellmound were "rediscovered" after a construction inspector noted archaeological material in the soil during industrial demolition. Archaeologists hired by the City of Emeryville Redevelopment Agency assessed the discovery and provided recommendations for conducting archaeological excavations and analyses to preserve important archaeological information from the portions of the site that would be destroyed by hazardous waste remediation and new construction.

Data Recovery
"Data recovery" is the process of excavation and recording that archaeologists use to obtain a sample of the materials present in the site, and of the information they represent. A plan for excavating at the site and processing the excavated material (a "data recovery plan") is developed before excavation starts, based on what is known about the deposit and the kinds of information - artifacts, strata and features - it might be expected to contain. Based on the kinds of materials known to be present and knowledge of similar sites, archaeologists develop research questions about the site before excavations begin. The research questions, data expectations and data recovery plan form a research design to guide archaeological investigations. The research design for the Emeryville Shellmound / Bay Street Project was peer-reviewed by 3 noted archaeologists, as well as by 3 Ohlone individuals who had expressed an interest in the site.

The data recovery plan for the Emeryville Shellmound / Bay Street Project included both hand and mechanical excavation. Archaeological fieldwork was carried out over a period of 3 1/2 months between August and November of 1999. Archaeologists excavated over 100 cubic meters (about 300 cubic feet) by hand with shovels and trowels. In addition, in order to learn more about the stratigraphy or layers of the site archaeologist also directed backhoe excavation of 28 trenches totaling over 520 linear meters in length (over 3/10 of a linear mile) at various locations around the site to depths of up to 3 meters (10 feet). These excavations provided information about site deposits over an area of more than 2 city blocks.

Logistical Site Problems
Data recovery at the Emeryville Shellmound posed some logistical problems. Because arsenic, lead and other potentially hazardous materials were present in the soil, archaeologists and Native American monitors received hazardous waste training and had to wear protective gear during excavation. The efforts of the archaeological team had to be coordinated with the ongoing efforts of environmental engineers and contractors to remediate the hazardous materials. Much of the major excavation required for the remediation took place during night hours.

Ground water, which rose and fell with the tides in nearby San Francisco Bay, had to be pumped to permit excavation near the base of the deposit, which was partially submerged. Because the archaeological soils were so wet, water screening was required to allow sample sorting and runoff had to be controlled so that it would not pollute Temescal Creek and San Francisco Bay.

In order to permit close inspection of layers in the trenches, trenches had to be shored. Additional mechanical excavation also was required to enable archaeologists to reach the bases of hand excavation units while still complying with required safety standards. The large size of the site presented logistical problems, which included the necessity of hauling material from distant units to wet screening stations. These challenges required hard work by a dedicated crew of 20 archaeologists and 2 Native American observers, as well as a full time backhoe operator.

Further Analysis
A construction trailer provided a field laboratory during the excavation period. Here, over 2,500 artifacts and samples were washed, labeled and cataloged. Partially processed samples, including many thousands of fragments of animal bones, hundreds of pounds of shells, and many seed, carbon and soil samples, were bagged and labeled for subsequent analyses by specialists at 4 universities and 6 additional laboratories.

After the field period, in a 2nd temporary laboratory near the site additional processing and analyses were conducted over a further 6-month period, again with Native American monitoring. Secondary analytic processes included soil sample flotation (separation of light materials like burnt seeds through use of very fine mesh screen in a water tank); shell sorting; artifact drawing, and photography and description. Because many of the artifact would be reintered with human remains from the site, many molds of artifacts also were prepared so that replicas could be produced for analysis and curation. Samples and nonburial artifacts then were taken to URS's facility in Oakland for distribution to specialist labs and for additional analyses.

Laboratory, Chemical & Microscopic Analyses
In the following 18 months, archaeologists, geologists and geoengineers at the URS Oakland facility described artifacts in detail, assessed the stratigraphy (or layers) discerned during excavation to understand the history of the site's deposition, investigated the underlying geology of the site location, analyzed dietary shell, and described historic bottles recovered from a Shellmound Park trash pit at the site.

Beta Analytic in Florida, a radiocarbon laboratory, dated almost 100 carbon samples from the site. UCLA's Zooarchaeology Laboratory and other specialists identified the species of thousands of mammal, fish and bird bones.
University of California, Los Angeles's (UCLA) Paleobotany Lab microscopically examined dozens of samples of carbonized seeds and plant material from the deposit. A microstratigraphy laboratory in Oregon prepared slides of microscopic thin sections of columns of soil preserved from the mound, for future analysis. At the University of California (UC), Berkeley, a specialist performed chemical isotope analyses of shell specimens, to obtain data on changes over time in temperature and salinity in the bay.

Geologists at Humboldt State performed detailed assessments of soil samples, to determine how soils and rock materials had been deposited on the site. Chemical and microscopic analyses were performed on hundreds of samples of obsidian (a volcanic glass used in the manufacture of chipped stone tools at the site), to provide information on the source of the material and the time period of tool manufacture. Bone and chipped stone tools were examined by other specialists to determine manufacturing techniques and changes in tool styles. UC Berkeley's forest products lab identified species of wood preserved in the deposit. At Sonoma State, a geomorphologist analyzed soil profiles to provide more information about how the site's deposition and underlying landforms.

The results of these and other analyses are described and synthesized in the lengthy technical report for the project, Emeryville Shellmound, 1999, which is available electronically on this website. You will find links to synopses of these results below.