WaterfallConnected
cavesSillSinkholeDikeFractureWater
Connected
cavesMt. RoraimaDec. Mt. WeiassipuWET DRYMar. Feb. Base (1,550)7,670 feetSummit (9,220)Underground
riversp(^600) feet deep
Nort
Cotingo River
Arabopó River
MOUNT
WEIASSIPU
Bountripdoarinty
Cave discoveries
Scientists recently discovered opal
stalactites, boulder-size colonies
of bacteria, underwater crickets,
and a new minside miles-long horizontal hollows. ineral, rossiantonite,
NATURE’S LABORATORY
COMPLEX FORMATIONS VARYING VEGETATION
ISOLATED TREASURES
Tepuis, island-like landforms towering thousands of feet above South American
savannas and rainforests, remain mostly untouched by humans. During the
past few decades, scientists have discovered a broad array of endemic plant
and animal species living in the tepuis’ high reaches and hidden interiors.
Structures within
Ancient mible today as layers of sandstone arine deposits are vis-
with varying patterns and grain
sizes. Chimcan be found inside the layers. neys of igneous rock
Rain dra
tepuis v
which fSouth Al
est rive
the Ama
Wthe rock, weathering it away into large ater expands natural fissures in
formations on tepui summits. Caves
are carved into the rock by under-
ground rivers that emcliff faces as waterfalls. erge from the
About a quarter of tepui plant species are endemic. Plants at the
highest altitudes are exposed to
intense solar radiation and frequent
heavy rains. In the short dry season, they’re stressed by drought.
Scientists are studying a new species found in the sinkhole above—
the Weiassipu pebble toad—to
see if it has genetic links to toads
discovered on other tepuis.
Outside pressures
Despite limits on visitors in a few of the
accessible tepuis, mthese fragile habitats and leaving behind any are trampling
environmentally destructive waste.
National Geographic Explorers
Bruce Means and Mark Synnott
rappelled into this sinkhole in 2012 and found what Means
called “a lost world within
a lost world.”
The heavy rains of the long wet season wane in December, leading to a short dry season.