Roraima Tepui (Canaima National Park, Venezuela)

Mount Roraima is the highest of a group of table-top mountains, known as tepuis, in South America.

1600 x 1200 jpeg 263 KB Credit: Jacek Staroszczyk Source: acaracas.blogspot.com

In the south-eastern corner of Venezuela, and also overlapping into parts of Brazil and Guyana, is the geological formation known as the Roraima Group. These sedimentary rocks, up to 3,000m deep, were laid down over 2 billion years ago as the ancient continent of Pangea was eroded by thousands of years of incessant rain, and remained unsubmerged as Gondwanaland was split apart under the forces of Continental Drift to form Africa and the South America. It is sobering to think that when the first plant life appeared these rocks were already at least 1.4 billion years old.

1600 x 1200 jpeg 691 KB Credit: Oxford University Cave Club Source: oucc.org.uk

The present-day tepuis, a Pemón Indian word for mountain, are believed to be remnants of the gigantic sandstone plateau which was selectively eroded after movements in the Earth’s crust caused points of weakness which were exploited by the great rivers of the region. Today the table mountains tower above the surrounding savanna, often with sheer cliffs of thousands of feet.

1600 x 1200 jpeg 238 KB Credit: BrianMig Source: picassaweb.google.com

The highest tepui in the Venezuelan Gran Sabana is Roraima, 2,810 metres, on the border with Brazil and Guyana. The name is a Pemón Indian word meaning ‘The large and ever-fruitful Mother of the streams”. Its 44 square mile plateau was first climbed by the English botanist Everard Im Thurn on an expedition sponsored by the Royal Geographical Society in 1884, and it was his subsequent lectures in England, together with those of Colonel P H Fawcett on the Serra Ricardo Franco range in Brazil, that are believed to have been the inspiration for Sir Arthur Conan Doyle’s ‘The Lost World”.