The Rhyacian is the second geologic period in the Paleoproterozoic

Paleoproterozoic

The Paleoproterozoic is the first of the three sub-divisions of the Proterozoic occurring between . This is when the continents first stabilized...

 Era and lasted from 2300 Mya to 2050 Mya (million years ago). Instead of being based on stratigraphy

Stratigraphy

Stratigraphy, a branch of geology, studies rock layers and layering . It is primarily used in the study of sedimentary and layered volcanic rocks....

, these dates are defined chronometrically.

The Bushveld Complex

Bushveld

The Bushveld is a sub-tropical woodland ecoregion of Southern Africa that encompasses most of Limpopo Province and a small part of the North West Province of South Africa, the Central and North-East Districts of Botswana and the Matabeleland South and part of th Matabeleland North provinces of...

 and other similar intrusion

Intrusion

An intrusion is liquid rock that forms under Earth's surface. Magma from under the surface is slowly pushed up from deep within the earth into any cracks or spaces it can find, sometimes pushing existing country rock out of the way, a process that can take millions of years. As the rock slowly...

s formed during this period.

The Huronian (Makganyene) global glaciation began at the start of the Rhyacian and lasted until 2200 Mya

The first known eukaryotes began to evolve in the Rhyacian period. The multicellular Francevillian Group Fossil

Francevillian Group Fossil

The Francevillian Group Fossil is an early, macroscopic organism. They were centimeter-sized highly organized, spatially discrete colonial organisms. Their fossils are found in the west-African country of Gabon in the Palaeoproterozoic Francevillian B Formation, a 2.1-Gyr-old black shale...

s, at 2.1-Gyr-old are from the Rhyacian period.