This volume represents some of the presentations at the 13th Colloquium of African Geology, held at the University of St Andrews, Scotland, in September 1985. The papers are grouped into sections based partly on a chronostratigraphic time scale starting with the Archaean and ending with modern sedimentological studies in coastal basins. There are, however, important themes linking all the papers irrespective of their time dependence. In particular, the studies on rifting, sedimentary basins and mineralization are developed as major reviews.