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  • I would like to invite you

  • to come along on a visit

  • to a dark continent.

  • It is the continent hidden

  • under the surface of the earth.

  • It is largely unexplored,

  • poorly understood, and the stuff of legends.

  • But it is made also of dramatic landscapes

  • like this huge underground chamber,

  • and it is rich with surprising biological and mineralogical worlds.

  • Thanks to the efforts of intrepid voyagers in the last three centuries --

  • actually, we know also thanks to satellite technology, of course --

  • we know almost every single square meter of our planet's surface.

  • However, we know still very little about what is hidden inside the earth.

  • Because a cave landscape, like this deep shaft in Italy, is hidden,

  • the potential of cave exploration -- the geographical dimension --

  • is poorly understood and unappreciated.

  • Because we are creatures living on the surface,

  • our perception of the inner side of the planet

  • is in some ways skewed,

  • as is that of the depth of the oceans

  • or of the upper atmosphere.

  • However, since systematic cave exploration started about one century ago,

  • we know actually that caves exist in every continent of the world.

  • A single cave system, like Mammoth Cave, which is in Kentucky,

  • can be as long as more than 600 kilometers.

  • And an abyss like Krubera Voronya, which is in the Caucasus region,

  • actually the deepest cave explored in the world,

  • can go as far as more than 2,000 meters below the surface.

  • That means a journey of weeks for a cave explorer.

  • Caves form in karstic regions.

  • So karstic regions are areas of the world

  • where the infiltrating water along cracks, fractures,

  • can easily dissolve soluble lithologies,

  • forming a drainage system of tunnels, conduits --

  • a three-dimensional network, actually.

  • Karstic regions cover almost 20 percent of the continents' surface,

  • and we know actually that speleologists in the last 50 years

  • have explored roughly 30,000 kilometers of cave passages around the world,

  • which is a big number.

  • But geologists have estimated that what is still missing,

  • to be discovered and mapped,

  • is something around 10 million kilometers.

  • That means that for each meter of a cave that we already know,

  • that we have explored,

  • there are still some tens of kilometers of undiscovered passages.

  • That means that this is really an endless continent,

  • and we will never be able to explore it completely.

  • And this estimation is made without considering other types of caves,

  • like, for example, inside glaciers or even volcanic caves,

  • which are not karstic, but are formed by lava flows.

  • And if we have a look at other planets like, for example, Mars,

  • you will see that this characteristic

  • is not so specific of our home planet.

  • However, I will show to you now that we do not need to go to Mars

  • to explore alien worlds.

  • I'm a speleologist, that means a cave explorer.

  • And I started with this passion when I was really young

  • in the mountains not far from my hometown in North Italy,

  • in the karstic regions of the Alps and the Dolomites.

  • But soon, the quest for exploration brought me to the farthest corner

  • of the planet, searching for new potential entrances

  • of this undiscovered continent.

  • And in 2009, I had the opportunity to visit the tepui table mountains,

  • which are in the Orinoco and Amazon basins.

  • These massifs enchanted me from the first time I saw them.

  • They are surrounded by vertical, vertiginous rock walls

  • with silvery waterfalls that are lost in the forest.

  • They really inspired in me a sense of wilderness,

  • with a soul older than millions and millions of years.

  • And this dramatic landscape inspired among other things

  • also Conan Doyle's "The Lost World" novel in 1912.

  • And they are, really, a lost world.

  • Scientists consider those mountains as islands in time,

  • being separated from the surrounding lowlands

  • since tens of millions of years ago.

  • They are surrounded by up to 1,000-meter-high walls,

  • resembling a fortress, impregnable by humans.

  • And, in fact, only a few of these mountains have been climbed

  • and explored on their top.

  • These mountains contain also a scientific paradox:

  • They are made by quartz,

  • which is a very common mineral on the earth's crust,

  • and the rock made up by quartz is called quartzite,

  • and quartzite is one of the hardest and least soluble minerals on earth.

  • So we do not expect at all to find a cave there.

  • Despite this, in the last 10 years, speleologists from Italy,

  • Slovakia, Czech Republic, and, of course, Venezuela and Brazil,

  • have explored several caves in this area.

  • So how can it be possible?

  • To understand this contradiction, we have to consider the time factor,

  • because the history of the tepuis is extremely long,

  • starting about 1.6 billion years ago with the formation of the rock,

  • and then evolving with the uplift of the region 150 million years ago,

  • after the disruption of the Pangaea supercontinent

  • and the opening of the Atlantic Ocean.

  • So you can imagine that the water had tens or even hundreds of millions of years

  • to sculpt the strangest forms on the tepuis' surfaces,

  • but also to open the fractures and form stone cities, rock cities,

  • fields of towers which are characterized in the famous landscape of the tepuis.

  • But nobody could have imagined

  • what was happening inside a mountain in so long a time frame.

  • And so I was focusing in 2010 on one of those massifs,

  • the Auyán-tepui, which is very famous because it hosts Angel Falls,

  • which is the highest waterfall in the world --

  • about 979 meters of vertical drop.

  • And I was searching for hints of the existence of cave systems

  • through satellite images,

  • and finally we identified an area of collapses of the surface --

  • so, big boulders, rock piles --

  • and that means that there was a void below.

  • It was a clear indication that there was something inside the mountain.

  • So we did several attempts to reach this area,

  • by land and with a helicopter,

  • but it was really difficult because -- you have to imagine

  • that these mountains are covered by clouds most of the year, by fog.

  • There are strong winds,

  • and there are almost 4,000 millimeters of rainfall per year,

  • so it's really, really difficult to find good conditions.

  • And only in 2013 we finally landed on the spot

  • and we started the exploration of the cave.

  • The cave is huge.

  • It's a huge network under the surface of the tepui plateau,

  • and in only ten days of expedition,

  • we explored more than 20 kilometers of cave passages.

  • And it's a huge network of underground rivers,

  • channels, big rooms, extremely deep shafts.

  • So it's really an incredible place.

  • And we named it Imawarì Yeuta.

  • That means, in the Pemón indigenous language, "The House of the Gods."

  • You have to imagine that indigenous people have never been there.

  • It was impossible for them to reach this area.

  • However, there were legends about the existence

  • of a cave in the mountain.

  • So when we started the exploration,

  • we had to explore with a great respect,

  • both because of the religious beliefs of the indigenous people,

  • but also because it was really a sacred place,

  • because no human had entered there before.

  • So we had to use special protocols

  • to not contaminate the environment with our presence,

  • and we tried also to share with the community,

  • with the indigenous community, our discoveries.

  • And the caves represent, really, a snapshot of the past.

  • The time needed for their formation

  • could be as long as 50 or even hundreds of millions of years,

  • which makes them possibly the oldest caves that we can explore on earth.

  • What you can find there is really evidence of a lost world.

  • When you enter a quartzite cave,

  • you have to completely forget what you know about caves --

  • classic limestone caves or the touristic caves

  • that you can visit in several places in the world.

  • Because what seems a simple stalactite here

  • is not made by calcium carbonate, but is made by opal,

  • and one of those stalactites can require tens of millions of years to be formed.

  • But you can find even stranger forms, like these mushrooms of silica

  • growing on a boulder.

  • And you can imagine our talks when we were exploring the cave.

  • We were the first entering and discovering those unknown things,

  • things like those monster eggs.

  • And we were a bit scared because it was all a discovery,

  • and we didn't want to find a dinosaur.

  • We didn't find a dinosaur.

  • (Laughter)

  • Anyway, actually, we know that this kind of formation,

  • after several studies,

  • we know that these kinds of formations are living organisms.

  • They are bacterial colonies using silica to build mineral structures

  • resembling stromatolites.

  • Stromatolites are some of the oldest forms of life that we can find on earth.

  • And here in the tepuis,

  • the interesting thing is that these bacteria colonies have evolved

  • in complete isolation from the external surface,

  • and without being in contact with humans.

  • They have never been in contact with humans.

  • So the implications for science are enormous,

  • because here you could find, for example, microbes

  • that could be useful to resolve diseases in medicine,

  • or you could find even a new kind of material with unknown properties.

  • And, in fact, we discovered in the cave a new mineral structure for science,

  • which is rossiantonite, a phosphate-sulfate.

  • So whatever you find in the cave, even a small cricket,

  • has evolved in the dark in complete isolation.

  • And, really, everything that you can feel in the cave are real connections

  • between the biological and the mineralogical world.

  • So as we explore this dark continent

  • and discover its mineralogical and biological diversity and uniqueness,

  • we will find probably clues about the origin of life on our planet

  • and on the relationship and evolution of life

  • in relationship with the mineral world.

  • What seems only a dark, empty environment

  • could be in reality a chest of wonders

  • full of useful information.

  • With a team of Italian, Venezuelan and Brazilian speleologists,

  • which is called La Venta Teraphosa,

  • we will be back soon to Latin America,

  • because we want to explore other tepuis in the farthest areas of the Amazon.

  • There are still very unknown mountains,

  • like Marahuaca, which is almost 3,000 meters high above sea level,

  • or Aracà, which is in the upper region of Rio Negro in Brazil.

  • And we suppose that we could find there even bigger cave systems,

  • and each one with its own undiscovered world.

  • Thank you.

  • (Applause)

  • Bruno Giussani: Thank you, Francesco. Give me that to start so we don't forget.

  • Francesco, you said we don't need to go to Mars to find alien life,

  • and indeed, last time we spoke, you were in Sardinia

  • and you were training European astronauts.

  • So what do you, a speleologist, tell and teach to the astronauts?

  • Francesco Sauro: Yeah, we are -- it's a program of training

  • for not only European, but also NASA, Roskosmos, JAXA astronauts, in a cave.

  • So they stay in a cave for about one week in isolation.

  • They have to work together in a real, real dangerous environment,

  • and it's a real alien environment for them because it's unusual.

  • It's always dark. They have to do science. They have a lot of tasks.

  • And it's very similar to a journey to Mars

  • or the International Space Station.

  • BG: In principle. FS: Yes.

  • BG: I want to go back to one of the pictures

  • that was in your slide show,

  • and it's just representative of the other photos --

  • Weren't those photos amazing? Yeah?

  • Audience: Yeah!

  • (Applause)

  • FS: I have to thank the photographers from the team La Venta,

  • because all of those photos are from the photographers.

  • BG: You bring, actually, photographers with you in the expedition.

  • They're professionals, they're speleologists and photographers.

  • But when I look at these pictures, I wonder: there is zero light down there,

  • and yet they look incredibly well-exposed.

  • How do you take these pictures?

  • How do your colleagues, the photographers, take these pictures?

  • FS: Yeah. They are working in a darkroom, basically,

  • so you can open the shutter of the camera

  • and use the lights to paint the environment.

  • BG: So you're basically --

  • FS: Yes. You can even keep the shutter open for one minute

  • and then paint the environment.