Tepuis are huge table-top mountains rising from the jungles of the Gran Sabana of Venezuela and Guayana. Their massive size and sheer walls make them impressive enough that when Sir Walter Raleigh wrote of the tepuis in 1595 he was widely disbelieved. It wasn't until Robert Schomburgk's report of these mountains during the 19th century that their existence was confirmed by Europeans.
The highest tepui is Roraima which towers above the surrounding forest 2810 meters or almost two miles. This tepui was one of the inspirations for Sir Conan Doyle's book The Lost World. The largest tepui is the Auyan-tepui with an area of 700 square kilometers. Auyan is the site of the highest waterfall in the world, Angel Falls, which plunges over 979 meters. It is 15 times higher than Niagara Falls, and the water that leaves the summit takes fourteen seconds to reach the bottom. The tepuis (a Pemon Indian word for mountain) are believed to be remnants of the huge sandstone plateau that was once Gondwanaland before the forces of Continental Drift split Africa and South America.
The tepuis, because of their isolation from each other and from the forest floor far below are of extreme interest for botanists to study the evolution of plants. Over 2000 species have been found on the tepuis, and a staggering 50% are endemic to only the tepuis, with many being found only on one peak. Because the tepuis are almost constantly enshrouded in clouds, they are considered a 'rain desert' where the constant washing action of the rain, combined with the high levels of radiation from the sun mean that the plants have to develop unusual mechanisms to survive. This is the only place on earth where carnivorous bromeliads have been found. It is also one of the only places where 100% of the species are native, not introduced.