Spatial Analysis

Research and Innovative Methods in Archaeology: Seeing Archaeological Landscapes through Spatial Analysis

Geomorphological and Archaeological Reconstructions at CA-SDI-811, MCB Camp Pendleton

CA-SDI-811 is a large coastal shell midden located on the Las Flores Creek flood plain in San Diego County, Camp Pendleton, California. This site presented a unique challenge in terms of investigating deeply buried archaeological deposits in the context of a changing geomorphological environment. To address these problems, a method using a mechanical drilling rig was utilized for this project. The site was tested with over 50 cores using a specially designed sample barrel. These samples were examined by a geomorphologist who then used the data to produce both 2D and 3D spatial reconstructions of the past environment.

The geomorphology results show that during the last 8,000 years, this dynamic flood plain has shifted between a lagoon, a freshwater marsh, an incised river, and a braided stream channel. The archaeological results indicate deposits are found at depths up to 7.2 meters, and range in time from historic to 7,800 BP. A 3D spatial model of the archaeology by strata shows that the deposits do not form one continuous occupation, but many discrete episodes of occupation that shift horizontally through time (as represented in the vertical distribution). This project was successful in that it revealed the distribution of archaeology in a geomorphological context, allowing for more precise examinations in the future. More importantly, this particular site demonstrates how the archaeology can only be fully appreciated in the context of changing geomorphology.

John R. Cook, Mark S. Becker, and Associates

Using Ground Penetrating Radar (GPR) to Locate Archaeology at CA-SDI-10723, MCB Camp Pendleton

CA-SDI-10723 is a coastal shell midden site located on a bluff overlooking the Las Flores Creek flood plain in San Diego County, California. The site has two components. The upper component is Late Prehistoric and dates between 300-500 years ago. The lower component is Early Archaic and dates to around 8,000 years ago. While much of the site was destroyed by historic farming and military activities, two small intact areas were identified during an evaluation phase. Prior to a data recovery project, both areas were examined with ground penetrating radar (GPR) to help locate potential archaeological deposits and features. Two antennas were used, a 200 MHz and 400 MHz in combination with a GSSI SIR 3000 digital control unit. Numerous anomalies were identified by the GPR. Investigations of these anomalies have shown them to be a combination of either cultural features, large rodent burrows, or natural features associated with geologic strata. Furthermore, investigations of areas with no anomalies did not produce either cultural or natural features. This method, still in an early stage, could allow archaeologists to focus on very specific areas to increase probabilities of finding cultural features.

Mark S. Becker