It identifies and explains the three rock groups (igneous, sedimentary, and metamorphic) very simply and clearly and even threw in some of the basic geological terminology such as obsidian (volcanic glass).
(It; identifies; ) (It; explains; the three rock groups (igneous, sedimentary, and metamorphic) very simply and clearly and even threw in some of the basic geological terminology such as obsidian)
It It
identifies explains
the three rock groups (igneous, sedimentary, and metamorphic) very simply and clearly and even threw in some of the basic geological terminology such as obsidian