Soil color in South Africa's Mpumalanga Highveld varies between topsoil and subsoil layers due to different minerals and wetness levels. A study of 422 soil points showed that topsoil color doesn't always match subsoil color, especially in certain soil types. Lighter-colored topsoil layers over yellow-brown subsoil layers are not indicative of the subsoil color. These lighter topsoil layers also have less clay than the underlying subsoil layers. This finding has important implications for classifying soils, understanding hillslope hydrology, and mapping soils from aerial and satellite images.