High Quality Content by WIKIPEDIA articles! The Guiana Shield is one of the three cratons of the South American Plate. It is a 1.7 billion year old Precambrian geological formation in northeast South America that forms a portion of the northern coast. The higher elevations on the shield are called the Guiana Highlands, which is where the impressive and mysterious table-like mountains called tepuis are found. The Guiana Highlands are also the source of some of the world`s most spectacular waterfalls such as Angel Falls, Kaieteur Falls and Kuquenan Falls.