TOPOGRAPHY
| Mercury's surface is similar to the lunar landscape. It is characterized almost exclusively by craters, overlapping craters, and craters within craters. The appearance is much like the earth's moon although the lunar surface has more large and open areas known as Maria or seas. The main impact feature is the Caloris Basin which is marked by hundreds of relatively smaller craters and is the only major open plain comparable to the Moon's Maria. Unlike the lunar seas, which are ancient lava flows. The Caloris Basin is so called because it is near a "hot pole" (one or two) in a region of the highest temperature, around 650° F (345° C). It is 1.287 km in diameter and is ringed by smooth mountains that rise to about 2,000 meters. This is possibly caused by seismic waves during the expansion and contraction of Mercury's core as it cooled and shrank. There is evidence of ancient volcanic activity on Mercury but less than on the Moon. |