Sima Humboldt (Sima Mayor) is an enormous

sinkhole A sinkhole is a depression or hole in the ground caused by some form of collapse of the surface layer. The term is sometimes used to refer to doline, enclosed depressions that are locally also known as ''vrtače'' and shakeholes, and to openi ...

located on the summit of the plateau of Sarisariñama

tepui A tepui , or tepuy (), is a table-top mountain or mesa found in South America, especially in Venezuela and western Guyana. The word tepui means "house of the gods" in the native tongue of the Pemon, the indigenous people who inhabit the Gra ...

in Bolívar State,

Venezuela Venezuela (; ), officially the Bolivarian Republic of Venezuela ( es, link=no, República Bolivariana de Venezuela), is a country on the northern coast of South America, consisting of a continental landmass and many islands and islets in th ...

. It is unusual for several reasons, including its enormous size and depth, its location on the top of the only forested

, having a patch of forest on its base and also due to the weathering process that formed this sinkhole. The feature is named after scientist and explorer

Alexander von Humboldt Friedrich Wilhelm Heinrich Alexander von Humboldt (14 September 17696 May 1859) was a German polymath, geographer, naturalist, explorer, and proponent of Romantic philosophy and science. He was the younger brother of the Prussian minister ...

. Together with the neighbouring

Sima Martel Sima Martel (Sima Menor) is an enormous sinkhole located on the summit of plateau of Sarisariñama tepui, in Bolívar State (Venezuela), Bolívar State, Venezuela. It is unusual due to several factors including its enormous size and depth, locati ...

, it was first spotted in 1961 by pilot Harry Gibson. The sinkhole was descended for the first time in 1974 and more thoroughly explored in 1976. Its volume is , with a maximum width of at its upper rim and below, and a depth of .(In Spanish) Miguel Lentino, Diana Esclasans. "Important Areas for the Conservation of Birds in Venezuela". In: ''Birdlife and Conservation International. Important Areas for the Conservation of Birds in the Tropical Andes: Priority Sites for the Maintenance of Biodiversity''. ("Áreas Importantes Para La Conservación De Las Aves En Venezuela". In: ''BirdLife International y Conservation International. Áreas Importantes para la Conservación de las Aves en los Andes Tropicales: sitios prioritarios para la conservación de la biodiversidad''.) Quito, Ecuador: BirdLife International (Serie de Conservación de BirdLife No. 14), S. 621-730, 2005. Only 700 metres from the rim of Sima Humboldt there is another enormous sinkhole, Sima Martel. In total there are four caves on Sarisariñama.

References

{{Tepuis , Venezuela Quartzite caves Geography of Bolívar (state) Caves of Venezuela Sinkholes of South America