AS16-120-19244(H)

Figure 69

 Click here for larger NASA image
 Click here for larger area from Figure 91 (AS16-2824)
 Click here for lunar chart showing location

This cluster of features in Mare Cognitum was photographed in color with a handheld camera and 250-mm lens. Its location on a mare ridge is shown in Figure 91 link above. Thomas K. Mattingly, the astronaut who took the picture, noted the taluslike skirt of material around the base of this and many other positive relief areas in the western maria. In this photograph the apparent difference in tone (and in color on the original negative) between the hills and the slightly darker skirt of material around their base is largely, if not entirely, due to differences in slope-a more steeply sloping surface appears brighter, as in the walls of craters in the adjacent mare. However, a real color difference has been found at the base of other prominences. The suggestion has been made that in some mare basins the original level to which lava filled the basin has receded and that skirts such as these are, in effect, "bathtub rings" recording the higher level. The two hills pictured here are probably of volcanic origin. -M.C.M.