Its field characteristics are especially suited to enhancements like PCA and ratioing. The abundant exposures of rocks rather than soil and vegetation cover make discriminating them easier and hence improve the classification accuracy's over most geological units, particularly those in areas where the units are hidden by weathering products and organic growth. As we have always known for aerial photographs, space imagery has limited value for direct mapping in vegetated terrains, so that field observations requiring on-site inspection and even digging remain the traditional way to map rock units. The area imaged is the Saline Valley which lies to the west of Death Valley and is hemmed in by the Inyo Mountains to its west and the Eureka Range to its east. In the image, red is vegetation, snow and sand are white, and rocks are gray, brown, yellow, and blue.
Limestone appears in yellow-greens and rocks altered to kaolinite as one of the clays are purple.
Resolution is 90 m.