323k GIF - 141k JPEG
The Argyre Basin
The largest craters or impact basins on Mars may be buried beneath the northern smooth plains. In the southern hemisphere, the bombardment history typical of all the inner planets is recorded by a few large basins, such as Argyre. The ring of mountains surrounding the basin probably rises 5 kilometers (3 miles) above the basin floor. The Mars Global Surveyor mapping mission has provided accurate elevation data that have answered many questions about Mars.
| Eroded Highland Terrain
Rather than the relatively blocky craters found on the Moon, the oldest terrain on Mars shows degradation of crater rims and evidence of erosion by running water. A comparison of the number of craters in the Martian highlands versus those on the Moon suggests that even the earliest crust of Mars may have long since been buried by more recent volcanic deposits.
A Young Crater
Even the youngest craters on Mars
display lobate ejecta patterns that may indicate subsurface water or
ice. This 30-kilometer (18-mile) crater is the result of a meteorite
impact on smooth plains of the northern hemisphere, blanketing the surrounding
terrain for up to 70 kilometers (42 miles) around.
See Water? for more on craters.
Seasons || Volcanoes
|| Canyons & Plains || Craters
|| Water? || Wind
The Surface of Mars
Mars and its Moons
|| Observation || Exploration
|| Viking Mission || Surface
Global View || Meteorite || Imagery || Links
Exploring The Planet