The Guiana Shield 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 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.
The Guiana Shield underlies Venezuela, Guyana (previously British Guiana), Suriname (previously Dutch Guiana) and French Guiana (or Guyane), as well as parts of Colombia, and Brazil.
(adapted from Wikipedia)