For the more information about the geologic resources of the National Park Service, please visit

Oldest Rocks

Oldest Rocks

During the immense span of time that has elapsed since life first emerged on the Earth 3.4 billion years ago, environmental conditions have changed and different groups of plants and animals have appeared, flourished, and disappeared. Our knowledge of this history is derived from the rocks that comprise the crust of the Earth. Over the years scientists have written the geological history of the earth by studying the composition, structure, and relationship of rocks and the fossils they contain.

The oldest rocks in the parks are Precambrian in age, from 3 billion to 600 million years old. This time interval saw the development of algae, fungi, and soft-bodied marine plants and animals. The distribution of Precambrian rocks is worldwide, but in the United States rocks of this age are found in the cores of major mountain ranges. They also occur in the Lake Superior region and in a few localities in the southwest.

Precambrian Geology - East

Precambrian Geology - West

Explore Further

| Tour of Park Geology | Geologic Time | Education & Outreach |


Last Updated: January 03, 2017