Geography of Mars
Now we are looking at a mercator projection of the surface of Mars. This map can be found in many pages of the Mars section of our site. We recommend looking at the large version of this picture carefully. Again, the surface of Mars can be broken into two main regions: highlands and lowlands. The highlands are in the southern hemisphere (the bottom of the figure), and the lowlands are in the northern hemisphere of Mars (top of the figure). The lowlands also contain the Tharsis Ridge. Measurements returned by Mars Global Surveyor demonstrate the severe height difference between these two regions of Mars.
The highlands are heavily cratered, and hence a very old portion of Mars, but the lowlands also contain a great deal of cratering. The cratering evidence suggests that the lowlands may be younger than the highlands.
Not seen clearly in this image are the Martian polar caps. Besides ice, the southern polar region of Mars contains other interesting geologic features such as layered terrain and giant sand dunes. This region would have been studied by the Mars Polar Lander, but the mission failed.