Meridiani Planum is one of the more geologically complex regions on Mars, featuring a rich array of sedimentary, volcanic, and impact surfaces that span a considerable range of Martian history. Located 2° south of the martian equator, its relatively non-threatening terrain combined with its geologic features led to it being selected as the landing site for the second of the Mars Exploration Rovers.

Meridiani Planum was dubbed the "Hematite Region" when scientists discovered significant deposits of gray hematite there. This is an iron-bearing mineral that, on Earth, is usually formed by the long-term action of water and is therefore of interest in the search for past life on Mars.