Academic journal article Southeastern Archaeology

Multisensor Geophysical Survey Results from the Pine Tree Mound Site: A Comparison of Geophysical and Excavation Data

Academic journal article Southeastern Archaeology

Multisensor Geophysical Survey Results from the Pine Tree Mound Site: A Comparison of Geophysical and Excavation Data

Article excerpt

Introduction

Early in 2006 Archaeo-Physics, LLC was contracted by Prewitt and Associates, Inc. to conduct a geophysical investigation at the Pine Tree Mound site (41HS15), a Caddo archaeological site located in Harrison County, Texas. Geophysical methods were used to evaluate two areas of the site that were slated for archaeological data recovery prior to portions of the site being destroyed by coal (lignite) mining operations. The objective of the investigation was to identify geophysical anomalies and anomalous patterning indicative of the presence of archaeological features and /or landscape modifications associated with the Caddo occupation.

Multiple geophysical methods were employed during the investigation, including magnetic field grathent, electrical resistivity, and ground-penetrating radar (GPR). Geophysical fieldwork was conducted between February 10-14, 2006. Parts of the Pine Tree Mound site were subsequently excavated during 2006 by Prewitt and Associates, Inc. Because each of the geophysical methods applied during this investigation responds to contrasts in different material properties, each individual method provides only a partial or limited understanding of the subsurface archaeological record. The view provided by each method is limited further when additional issues inherent to most real world geophysical survey situations are considered. For example, signal noise caused by system electronics, environmental conditions, and operator error can limit the visibility of buried archaeological resources. Signal clutter is often an even more significant source of uncertainty. It can be caused by modern trash (e.g., metal pin flags), modern disturbance (e.g., plowing, terracing, trenching), natural horizontal or vertical heterogeneity in the site's soils, and the presence of natural inclusions within the soil (e.g., stones with significant magnetic remanence). These three issues - limited signal contrast, signal noise, and signal clutter - often result in significant uncertainties when interpreting geophysical data from pre-contact Native American sites.

In a similar manner, there is often considerable uncertainty associated with the excavation and mapping of archaeological features. This is especially true in salvage archaeology situations where mechanical methods are utilized to explore large areas and time and budget constraints must be considered. Although many buried archaeological features are highly visible and easy to interpret, we believe most field archaeologists would agree that features often grade into ambiguity, and the mapping and recording of such features can be very subjective and challenging. With these many sources of uncertainty in mind, the archaeological record at a large and complex site such as the Pine Tree Mound site is best understood by carefully comparing all available sources of data. Toward this end, a web-based interactive data exploration and analysis application was created. This tool may be used to explore the results of the multivariate geophysical investigation at the site and carefully compare these data with a plan map of features encountered during the archaeological investigation.

The online application was created using a software package called FLASH, distributed by Adobe Systems. The FLASH software package utilizes a scripting language, known as ActionScript, to create a highly interactive and adaptable environment capable of manipulating and displaying both raster and vector graphics. Presentation in FLASH format is an effective means of making Geographic Information System (GIS) content available to both the public and professionals via the web. FLASH viewing software is readily available, free, and works well across most major operating systems and web browsing platforms.

This article will describe how the interactive application may be used by professional and avocational archaeologists to better understand the complex multivariate data obtained from this important Caddo site. …

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