Onverwacht Group

The Onverwacht Group or Onverwacht Series is a series of greenstone belts and volcanic rock formations from the Archean Eon in the Kaapvaal Craton in South Africa and Eswatini.

A well known part of the Onverwacht Series is visible in the Komati valley, located in the east of the Transvaal region.

Subdivision
The Onverwacht Group can be divided into two subgroups with six formations:
 * Geluk Subgroup
 * Swartkoppie Formation – 920 m
 * Kromberg Formation – 1920 m
 * Hooggenoeg Formation – 4850 m
 * Tjakastad Subgroup
 * Komatii Formation – 3500 m
 * Theespruit Formation – 1980 m
 * Sandspruit Formation – 3200 m

The fossils found in the Onverwacht Series are among the oldest found on Earth.