Figure 15. Results are shown for retrieval and concentration mapping of spectral endmembers for Mount Desert Island and Sands of Forvie. This assumes that the spectra mix linearly, i.e., in a checkerboard fashion. The three aerially important endmember spectra are shown on the lower left and mapped using the same color coding on the areas covered for the ROIs. The red spectrum and reddish colors mapped on the ROIs correspond to bedrock regions mapped within the intricate edges of the Mount Desert Island region and the southern part of the Sands of Forvie. The northern part of the Sands of Forvie maps as a mixture of bedrock contaminated areas and sand with an enhanced long wavelength positive slope (i.e., purple areas). The southern area within the sand sheet exhibits green colors typical of the mean for Sands of Forvie.
The other two endmember spectra share similarities with the mean spectra for the two sand deposits, one with a long wavelength rise (MDI, Figure 16) and the other with a broad and relatively deep ~2.2 µm absorption (SoF, Figure 17). Detailed analysis of the abundance map shows the former spectrum is more abundant in the MDI dune and the latter in the SoF sand sheet. The two spectra share a broad, not well defined, ~1 µm spectral feature that is also evident in the mean spectra for the two sand bodies. Note that endmember spectra shown in these latter two figures were derived by taking the means of the abundances for fractional proportions greater than 0.75 in each case.