A Formation is a group of rocks that are related by the way they were formed and the time in history in which they were formed.

Is the rock in this formation igneous, sedimentary or metamorphic?

In other words, was if formed by being melted, flowed, and cooled? Or Was it formed by weathering, erosion, and deposition, or through an organism's life processes? Or Was it formed by subjecting rocks to extreme heat and pressure?