A geobotanical investigation based on the detection of premature leaf senescence was conducted in an area of predominantly chalcocite mineralization on the Keweenaw Peninsula in Michigan's Upper Peninsula. As a preliminary step, spectral reflectance measurements of a variety of fall leaves are illustrated. The spectrophotometric measurements suggest that a bandpass from 600 to 700 nm captures the rise in the red reflectance characteristic of any color senescent leaf and that observations at other wavelengths do not distinguish between senescent and green leaves as clearly and unequivocably as observations at these wavelengths. Small format black and white aerial photography filtered for the red band (600-700 nm) was used to identify two sites in the study area characterized by premature leaf senescence of the dominant flora in an area suspected of containing anomalous concentrations of soil copper but for which the geochemical data were lacking. Soil samples were collected from the two sites and from two additional sites in which the leaf canopy was still green. Geochemical analysis revealed that the sites characterized by premature leaf senescence had a significantly higher median soil copper concentration than the other two sites.