The surface of Mars is 144.8 million km²
The surface is primarily composed of tholeiitic basalt, it’s dry and wasteland because of the vulcanical eruptions that happened millions of years ago
The Red Planet’s total surface area is about 28% of Earth. It doesn’t sound like a big planet at all, but it is nearly equivalent to all of the dry land on Earth. The surface is thought to be mostly basalt, covered by a fine layer of iron oxide dust that has the consistency of talcum powder. Iron oxide(rust as it is commonly called) gives the planet its characteristic red hue. Because of the vulcanical eruptions, Mars is dotted with craters.
Many regions of Mars are flat, low-lying plains. The lowest of the northern plains are the flattest and the smoothest places in the solar system, created by water that once flowed across the Martian surface.
This difference between the north and south might be due to a very large impact shortly after the birth of Mars.
The number of craters on Mars varies dramatically from place to place, depending on how old the surface is.
Much of the surface of the southern hemisphere is extremely old, and so has many craters, including the planet’s largest, 1,400 mile-wide (2,300 km) Hellas Planitia .
While that of northern hemisphere is younger and so has fewer craters. Some volcanoes also have a few craters, which suggests they erupted recently, with the resulting lava covering up any old craters. Some craters have unusual-looking deposits of debris (scattered pieces of rubbish) around them resembling solidified mudflows (avalanche made of mud), potentially indicating that the impactor hit underground water or ice.