Paleoproterozoic

The Paleoproterozoic Era is the first part of the three divisions of the Proterozoic eon. It lasted a very long time, from 2,500 to 1,600 million years ago, making it the longest era in Earth's geological history. This era is split into four smaller time parts called geologic periods: the Siderian, Rhyacian, Orosirian, and Statherian.

Scientists think that during the Paleoproterozoic, a day on Earth was only about 20 hours long. This means that there were about 450 days in a year back then! This era was also very important because it is when the continents of the Earth first came together and stayed in place.

Atmosphere

Main articles: Prebiotic atmosphere, Geological history of oxygen, and Great Oxygenation Event

The early Earth's atmosphere was very different from today, filled mostly with nitrogen, methane, ammonia, carbon dioxide, and other gases that do not support breathing. This changed when simple plants called cyanobacteria began using sunlight to make food, a process called oxygenic photosynthesis. As these plants grew, they released a lot of dioxygen as a waste product. Over time, this oxygen built up in the air, leading to a major change known as the Great Oxidation Event. This event caused oxygen levels to rise sharply, changing the planet's air and making it possible for animals to breathe millions of years later.

Life

Further information: Symbiogenesis

At the start of the Archean eon, most life was made of simple single-cell prokaryotic organisms that did not need oxygen to live. After a big change called the Great Oxygenation Event, many of these old organisms could not survive because oxygen hurt their cells. This led to a long cold period called the Huronian glaciation, which caused one of Earth's first big die-offs of life.

Later, new types of organisms that could use oxygen began to thrive. This era, called the Paleoproterozoic, is when we find the oldest known fossils of special blue-green bacteria called cyanobacteria. Scientists also think that more complex cells, called eukaryotic organisms, began to appear during this time. These changes helped set the stage for even more kinds of life to develop later on Earth.

Geological events

During the Paleoproterozoic Era, the earliest large-scale collisions between continents occurred. These collisions formed mountain ranges in many parts of the world, including South America, West Africa, southern Africa, North America, Greenland, and Europe. These events helped create a supercontinent named Columbia or Nuna.

Volcanic activity formed important mineral deposits in what is now northern Sweden. Also, the oldest pieces of Earth's outer layer formed in parts of Patagonia's oldest blocks.