Figure 4. Plot of ASTER (Advanced Spaceborne Thermal Emission and Reflection Radiometer) emissivity spectra of surfaces in the Alligator Ridge–Bald Mountain area identified as containing either quartz or carbonate using ratio-based indices. Spectra of carbonate-bearing lithologies are shown at top. Jasperoids formed by hydrothermal processes are indicated in red at right. ASTER band centers are also shown. Note correspondence of spectral shapes with the reference spectra shown in Figures 1 and 2.