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.