Neoarchean

The Neoarchean (/ˌniːoʊ.ɑːrˈkiːən/ NEE-oh-ar-KEE-ən; also spelled Neoarchaean) is the last geologic era in the Archean Eon that took place from 2800 to 2500 million years ago. This time period is identified by measuring the time directly, rather than by looking at layers of rocks on Earth.

During the Neoarchean, important changes happened that helped shape our planet. Scientists believe this was when the first complex life forms began to appear. These early organisms were very different from simple bacteria and marked a big step in how life evolved.

This era was also a time when the continents started to come together and form larger landmasses. The way the land moved and changed during the Neoarchean helped create the foundations for the continents we know today.

Complex life

This era saw the rise of oxygen in the atmosphere after oxygenic photosynthesis evolved in cyanobacteria. The changes in the environment during this time helped different kinds of tiny life forms to develop and change. The growth of new land areas and the movement of Earth's plates allowed these tiny organisms to live in many different places.

The earliest signs of very simple life forms that might be related to more complex life we know today come from this time in South Africa. However, scientists are still not sure about these findings.

Continental formation

During the Neoarchean era, around 2.7 billion years ago, a supercontinent called Kenorland may have formed. Scientists are interested in Kenorland because it might have held important minerals like volcanic-hosted massive sulphide, gold, and uranium, especially in the Canadian Shield. However, recent studies suggest that Kenorland might not be the correct name, and other supercontinents like Superia or Vaalbara could have existed instead. Some parts of what was thought to be Kenorland, such as the Churchill Province, may have formed later, around 1.9 billion years ago, during a different time called the Nuna era.

The way supercontinents form and break apart, known as the supercontinent cycle, helps us understand how Earth’s crust changed over time since the time of Pangaea. The movement of Earth’s plates, or plate tectonics, created forces that caused changes in the continents through processes like metamorphism and magmatic activity. Studying these changes helps scientists connect what happens deep inside the Earth with what we see on the surface.