Making the world better, one answer at a time. Mars is made of rock and iron oxides. It's surface is covered in mountains, volcanoes, valleys, ice caps and dried up river beds. Mars is also very dry like a desert. It is also red because of the iron oxide in the pulverized rock dust. Mars is made of rock and iron oxides. It's surface is covered in mountains, volcanoes, valleys, ice caps and dried up river beds. Mars is also very dry like a desert. It is also red because of the iron oxide in the pulverized rock dust.