Tepuis

A tepui 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 Gran Sabana. Tepuis tend to be found as isolated entities rather than in connected ranges, which makes them the host of a unique array of endemic plant and animal species. They are typically composed of sheer blocks of Precambrian quartz arenite sandstone that rise abruptly from the jungle and can be the source the world's tallest waterfalls. Because of their great age, some tepuis exhibit surface features and caves typical of karst topography, formed in more water-soluble rocks such as limestone. Some of the mesas are pocked with giant sinkholes up to 300 meters (1,000 ft) in diameter and with sheer walls up to 300 meters (1,000 ft) deep. The plateaus of the tepuis are completely isolated from the ground forest, making them ecological islands. The altitude causes them to have a different climate from the ground forest. The top presents cool temperatures with frequent rainfall, while the bases of the mountains have a tropical, warm and humid climate.

The Lost World

The Lost World is a science fiction novel by British writer Sir Arthur Conan Doyle, published by Hodder & Stoughton in 1912, concerning an expedition to a tepui in the Amazon basin of South America where prehistoric animals still survive. It was originally published serially in the Strand Magazine and illustrated by New-Zealand-born artist Harry Rountree during the months of April–November 1912.

The Datapack

This datapack adds the tepuis as best I can. They are sheer-sided plateaus which rise high into the clouds. Within them you may find a beautiful but deadly cavernous realm of ancient life.