Topographic Features of the Lunar Maria and Basins

More than 70 topographic profiles of 34 large lunar maria and basins were constructed and studied in order to obtain quantitative values of the parameters that characterize these formations, to identify patterns and features of their relief. The dependence of the absolute height of the bottom and the depth of the basins on latitude, longitude, size and relative age has been investigated. The absolute height of the bottom of the formations in the visible hemisphere, as expected, is less than in the opposite hemisphere. In the longitudinal direction, there is a tendency for the depth of the basins to increase in the direction from the central meridian to the 180 meridian (from the center of the near side hemisphere to the center of the far side hemisphere). The ridges of the ramparts throughout each of the basins often have different heights. Depending on this difference in the heights of the ridges of the ramparts, three groups of basins are distinguished, which differ in height. It is assumed that the greater the height difference of the ridges of the ramparts, the more oblique was the fall of the impactor. The correlation of the above parameters with the relative age was not found in this study. Morphometric studies of impact ring structures on the Moon and their interpretation suggest that in the early evolutionary epoch of the lunar surface in the period of about 4.4–4.0 billion years, the main impactors were bodies of cometary nature from the Kuiper Belt or from the Oort Cloud.