Term

Precambrian Facts

Definition

Makes up over 88% of all geologic time. No rocks are known for the first 640 million years of earth. Subdivided into Hadean, Archean Eon, and Proterozoic Eon.

Term

Hadean

Definition

Oldest mineral Zircon from Australia dated at 4.4 billion years old, may confirm oldest continental crust existed at that time - shortly after the earth-moon system was formed.

Term

Shields

Definition

Large areas of exposed precambrian rock (canadian shield)