The Guiana Shield first appeared as a recognisable geological entity on 19th century and early 20 century geological maps of South America and Brazil. From the 1950ies onward concerted efforts by the three Guianas resulted in joint maps. Due to the difficult outcrop conditions, lack of fossils and of a reliable chronology, stratigraphies varied widely and orogenic events were largely described  on the basis of concepts developed in Phanerozoic belts.