As we bring to a close the publication of a selection of papers presented at the 18th Colloquium of African Geology, held in Graz, July 4-7, 2000, and look forward to the 19th Colloquium scheduled for El-Jadida, Morocco, in March 2002, this short contribution reflects on the origin of these colloquia and the influence they have had on African geological research.
The African continent is unique in many respects . In contrast to Europe, which was mobile throughout the Phanerozoic, Africa (excluding the marginal Alpine Haut Atlas, the Hercynian Mauritanides and Cape Coast belts), was a ''craton'' involved in several Pangeae and their fragmentation particularly Gondwana. During the past 30 years, major scientific contributions from Africa in a wide variety of subjects were first presented at one of the Colloquia of African Geology. These include: Archaean greenstone belts and granulite terrains; supercontinental construction and fragmentation; palaeomagnetism; terrane-accretion; continental rifting; Palaeoproterozoic-, Mesoproterozoic-and Neoproterozoic orogens; glaciations and the snowball earth; anorogenic volcanism and plutonism (alkaline ring complexes, carbonatites, kimberlites), mantle studies; komatiites; Sturtian and Vendian palaeontology, and hominid evolution.
The late Prof. W.Q. Kennedy convened the very first Colloquium of African Geology at the University of Leeds during the Easter vacation in 1964. There was a pulse of excitement that electrified the assembled audience when Prof. Kennedy announced his idea of a ''Pan-African thermal-tectonic event''. He had been involved with his research students, at the Institute of African Geology, on a series of projects collecting samples from various parts of Africa and having them dated using Rb-Sr techniques by Pat Hurley in the USA; Lucien Cahen at Tervuren, Belgium; and Maurice Roques in Clermont-Ferrand. Two distinct age patterns started to appear: those around 2000 Ma or older, and those bracketing the late Precambrian period of 800-600 Ma. The idea of Africa being constructed from 2000 Ma stable cratons surrounded by 800-600 Ma mobile belts was thus launched and had many young earth scientists completely hooked.
The Colloquia themselves had their original 'naissance' sometime earlier than 1964. In fact, such meetings of geologists assembling to discuss ''current research''