2006 Philadelphia Annual Meeting (22–25 October 2006)

Paper No. 10
Presentation Time: 4:00 PM


WILLIAMS, Thomas J., Department of Geological Sciences, University of Idaho, PO Box 443025, Moscow, ID 83844, tomw@uidaho.edu

Teaching Forensic Geology can be a daunting task. At the University of Idaho, Forensic Geology is a self-contained class with no prerequisites. It is open to both geology and non-geology majors and is probably the only forensic science class students will take. The class is organized around three goals: A.) develop fundamental geologic and forensic knowledge, B.) impart an interesting but realistic view of forensic science, and C.) provide an opportunity to obtain practical skills. The Materials Characterization Laboratory provides the resources and the following instrumentation to meet this goal: the Polarized Light Microscope (PLM), Powder X-ray Diffractometer (XRD), and Scanning Electron Microscope (SEM). Along with a binocular microscope, these instruments are utilized by many forensic laboratories for analysis of geologic evidence, and other types of trace evidence (e.g. hair and fibers, gun-shot residue). Hands on use of the instruments allow the students a rare experience with sophisticated laboratory technique; demonstrates what instruments can and cannot do; and helps clarify such topics as “refractive index,” “detection limit, “exemplar,” and “individualization.” Instruments in the classroom can also be interesting and fun. Our syllabus incorporates lectures and laboratory exercises devoted specifically to the PLM, XRD, and SEM. These instruments are then integrated into specific exercises such as Sands, Soils, Glass, Paint & Cosmetics, and Industrial Materials. In “Forensics of Glass,” students examine a variety of glass samples using the PLM and SEM to compare how variations in glass chemistry relate to refractive index. In “Sands of Crime,” students determine mineral chemistry using SEM and crystal structure “fingerprints” on the XRD. In “Cosmetics”, students examine traces of make-up on clothing using XRD to individualize the samples based on mineral assemblages. The PLM, XRD, and SEM are invaluable resources for teaching Forensic Geology and gives students the opportunity to hone skills in the examination the geologic materials that constitute what Edmond Locard called “…the mute witnesses, sure and faithful, of all our movements…” (Locard, 1930).