The surface of Mars contains many unique features, including prominent shield volcanoes, large canyons and caves, pronounced depressions from wind and water erosion and polar caps. In addition to having these features, Mars lacks some physical landmarks found on many other planets, such as plate tectonics. As a result, Mars has fewer towering volcanoes, and has smaller mountains as well.
Mars has quite a few geological surfaces that make it unique. Some features on Mars are visible by the naked eye while others are apparent only through telescopes, space ships and other astronomical equipment.
The shield volcanoes on the surface of Mars are virtually extinct, although they are still prominent features. These volcanoes, true to their name, resemble large shields in appearance. They have wide and relatively flat bases that form the shape of large rectangles and squares. Shield volcanoes may cover large distances, and have bases that span several hundred miles. These volcanoes may also reach great heights: the largest is Olympus Mons, which is double the size of Mount Everest.
Mars also has deep ridges along its surface formed from constant subjection to the pressures of wind and water, and has pronounced ice-covered polar caps along its northern and southern poles, which shrink and grow with the changes of the seasons.