SACS and the geological time scale

摘要

The South African Committee for Stratigraphy (SACS) coordinates the formal description of the stratigraphic units of South Africa. Using features that can be recognised in the field, the units are initially defined as lithostratigraphic units. Chronostratigraphic units are then defined using absolute ages derived from volcanic rocks interbedded within sedimentary packages. SACS (1980) recognises five Precambrian eras, the Swazian (oldest), Randian, Vaalian, Mokolian and Namibian (youngest).