Precambrian, Proterozoic Eon, Archeon Eon, and Hadean

Precambrian (Informal—4.6 billion years ago to 541 million years ago)

Precambrian is the informal name for the first 4 billion years, or 88 percent, of Earth’s history. It includes the Proterozoic and Archeon Eons. In Kansas and many other places, rocks formed during this time can only be found hundreds or even thousands of feet underground, making them difficulty to study.

No fossils from this time have been found in Kansas.

Proterozoic Eon (2.5 billion years ago to 541 million years ago)

Proterozoic igneous and metamorphic rocks are found deep under the surface.

Archeon Eon (4 billion years ago to 2.5 billion years ago)

Archeon rocks are not known in Kansas.

Hadean (informal) (4.6 billion years ago to 4 billion years ago)

Hadean rocks are not known in Kansas.