There are many craters caused by meteors crashing into its surface. Mars also has canyons, deep gorges, and volcanoes. In fact, Mars has some of the largest volcanoes in the Solar System . The southern hemisphere on Mars has highlands, made of ancient, most heavily cratered crustal material, much like the Moon. The northern hemisphere is made of plains and they are not as old.
Astronomers have evidence of erosion on many parts of Mars.
At one time on Mars, millions of years ago, there was water and maybe even lakes or oceans that flowed across the now dry red planet. Some of the metoerites found on Earth are actually pieces of Mars. They are being examined by scientists for evidence of tiny bacteria and other signs that life may have once existed on the planet. Millions of years ago, the two asteroids that are the moons came close enough to Mars that they were attracted or captured by Mars' gravitational field. The two moons are among the smallest moons in the Solar System.