APPLICATION OF GEOLOGIC METHODS TO 21ST CENTURY ARTIFACTS

Curious formal and informal students of the earth sciences often bring specimens to Geoscience departments at universities for identification. Increasingly, these specimens, while composed of earthen materials, are, in fact, simply artifacts of one or another processes undertaken by humans. The interest in these objects is keen, and the finders are frequently disappointed to be informed of the anthropogenic forces that form their treasures. In most such cases, the consulted geoscientist simply informs the treasure hunter, basing their assessment on their own experiences with natural materials. What if, however, studies of these materials were undertaken as they might be in the distant future, when current reference points have lapsed? Presumably, the investigative methods employed by geoscientists would still be relevant. This study applies traditional geologic methods—petrography, sedimentology, and stratigraphy—to ascertain the source of somewhat curious set of beach pebbles found on the beach and wash areas of Lake Michigan in Racine, Wisconsin. The pebbles were notable for embedded, euhedral pyrite crystals, and seemed to occur in conjunction with pinkish clay along a limited section of the lake shore. In order to attempt to eliminate the nearby power plant as a source, the following investigations were undertaken: Areas of occurrence, both above and below the water line, were assessed by transects. Subaqueous topography of the study area was also mapped. Samples were collected both from within the pink clay (subaqueous) and from the beach. The pink clay matrix was also sampled. Pebbles were cut into thin sections for petrographic analysis. Three sections of the bluff immediately above the beach were also described and sampled for stratigraphic context. Results of these investigations suggest that geologic methods will continue to be useful tools for hypothesis testing even if the cultural and terrestrial context changes dramatically.