Critical Thinking in Geology and Archaeology: Interpreting Scanning Electron Microscope Images of a Lithic Tool

Article excerpt

ABSTRACT

As co-instructors of an undergraduate course in Archaeological Geology, we have developed an in-class research project using the Scanning Electron Microscope (SEM) to analyze and interpret physical traces of stages in the history of a unique lithic artifact. This exercise requires preliminary instruction on percussion and pressure flaking, geological materials suited for chipped stone tool manufacture, contextual archaeological analysis, theory of electron microscope use, and post-depositional surface processes, particularly those creating natural wear due to wind or water abrasion. With this background, students acquired four images of surface and edge locations of the study artifact using the SEM. We asked students to write a description of the analytical technique, a compilation of their observations and analytical data, and an interpretation of the artifact's history. Although most students recognized that the artifact recorded multiple stages of manufacture and use, additional comparative images of water- or wind-worn, chipped or ground cherts would give students greater ability to distinguish cultural modifications from those created by post-depositional geologic processes. Students expressed enthusiasm about the project and indicated a high level of engagement on evaluations (mean score=4.3-4.4, median score=4.5-5.0 on a scale of 1 [low] to 5 [high]).

COURSE AND PROJECT GOALS

During the last fifteen years, reviews of national science education have strongly encouraged educators to use concrete, participatory experiences to improve students' abilities to design, implement and evaluate experiments and to retain scientific knowledge (AAAS, 1989; NRC, 1996, 2000). A wide variety of National Science Foundation-sponsored workshops and special sessions at national meetings (e.g., From the introductory classroom to capstone experience - integrating research into the undergraduate curriculum GSA, 2000, and Using data to teach earth processes, GSA 2003) continue to highlight innovative active-learning projects, many of which include primary research.

During the spring (2003) semester at Kansas State University (KSU), we developed and co-taught an interdisciplinary undergraduate course in Archaeological Geology that provided three credit hours in anthropology or geology. As key components of the course, we wished students to acquire: a) knowledge of geological processes that affected past human societies and the archaeological record, b) an introduction to analytical methods used by geologists that aid in the interpretation of our human past, c) an understanding of geologic time and dating techniques, and d) an appreciation for how geologic knowledge is critically applied toward the interpretation of the human past. In order to reach these goals, we designed and implemented seven participatory projects that stressed evaluation of geologic and archaeological data and the use of higher cognition skills, particularly synthesis and interpretation (Bloom et al., 1956).

For one of these activities we asked students to describe, analyze and interpret the history of a complex lithic tool (hafted knife or projectile point). By complex, we mean that the stone tool showed physical traces of multiple stages of manufacture and use. The primary goals of this activity included: a) distinguishing the study object as a cultural (artifact) rather than natural, b) identifying the methods of manufacture, and c) distinguishing characteristics imparted by post-depositional processes. Following macroscopic inspection, students collected compositional data and magnified images using a scanning electron microscope (SEM). Students learned to distinguish between collection of careful observations (data) and interpretation of those observations. Students wrote individual reports of their analyses that included their observations, evaluation of the data quality and an interpretation of the history of the study artifact. …