Figure 34

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A mosaic of seven metric camera frames showing the northern part of the Crisium basin. The inner lava flooded part of the basin is Mare Crisium. Basins, the principal features of the lunar terrae, are essentially large craters with more than one conspicuous concentric mountain ring. In the west half of this mosaic are two raised basin rings separated by a trough (between arrows) partly filled with mare lavas and light plains deposits. The higher and broader of the two rings forms the "shore" of Mare Crisium. In the east half of the mosaic, the rings are less obvious, partly because the Sun illumination is too high to cast prominent shadows and partly because the rings have been broken up by faulting and flooded by mare material. Craters are less numerous in this picture than in the previous one because many were destroyed or buried during the formation of the basin. Some basins, like Crisium, are deeply flooded by mare material, and others, especially on the far side, are flooded less or not at all. Therefore, the accumulation of mare material is not directly related to the formation of basins, and the terms "mare" and "basin" must always be kept distinct. -D.E.W.

Report Source: NASA SP-362, Page 48, Figure 34

This web page was created by Francis Ridge for The Lunascan Project
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