The PreCambrian

This section summarizes the most notable events of the PreCambrian, which spans geologic time for over 4 billion years from 4.6 billion and is broken down into three Eons: Hadean, Archean, and Proterozoic.

The Precambrian is the least-understood part of Earth’s history, yet it is arguably the most important. Precambrian time spans almost nine-tenths of Earth’s history, from the formation of the Earth to the dawn of the Cambrian Period. It represents a time so vast and long ago that it challenges all comprehension. The Precambrian is the time of big questions. How old is the Earth? How old are the oldest rocks and continents? What was the early Earth like? What was the early atmosphere like? When did life appear, and what did it look like? And how do we know this?

In recent years, remarkable progress has been made in understanding the early evolution of the Earth and life itself. Yet, the scientific story of the early Earth is still a work in progress, humankind’s latest attempt to understand the planet. Like previous attempts, it will change as we learn more about the Earth.