Dating crash course
According to NASA, the iron minerals oxidize, or rust, causing the soil to look red.
Geology The cold, thin atmosphere means liquid water currently cannot exist on the Martian surface for any length of time.
It is a shield volcano, with slopes that rise gradually like those of Hawaiian volcanoes, and was created by eruptions of lavas that flowed for long distances before solidifying.
Mars also has many other kinds of volcanic landforms, from small, steep-sided cones to enormous plains coated in hardened lava.
Olympus Mons is roughly 17 miles (27 kilometers) high, about three times as tall as Mount Everest, while the Valles Marineris system of valleys — named after the Mariner 9 probe that discovered it in 1971 — can go as deep as 6 miles (10 km) and runs east-west for roughly 2,500 miles (4,000 km), about one-fifth of the distance around Mars and close to the width of Australia or the distance from Philadelphia to San Diego.
Mars has the largest volcanoes in the solar system, including Olympus Mons, which is about 370 miles (600 km) in diameter, wide enough to cover the entire state of New Mexico.
This means that although this desert planet is just half the diameter of Earth, it has the same amount of dry land.
The red planet is home to both the highest mountain and the deepest, longest valley in the solar system.