National Geographic: Mysteries Underground Page #5

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of pearl-like formations found here.

Looking like fried eggs,

this kind of cave pearl is built up

from calcite in the water.

Another variety of cave pearl forms

when a single grain of sand

becomes coated with calcite.

Over time the relentless dripping

of water swivels the grain

and the coating becomes thicker,

like the creation of a pearl

in an oyster.

Lake Castrovalva guards

a remote corner of the cave.

The only way across is to swim.

But the conservation creed demands

that no dirty clothing soil its purity

The air and water temperatures

are the same year round 68 degrees.

Intricate stone formations

border the edge of the lake,

slowly deposited by waters rich

in calcite.

For eons these exotic shores

have been still and silent

calm until now.

Light on the station.

The primary function of any expedition

is to explore and survey the cave

to produce a detailed map.

Keeping accurate records is virtually

a religion for modern cavers.

Two thirty-nine, point five.

It's what separates them from earlier,

less responsible explorers underground

Plus four.

Plus four.

Finding something new is

the first great thrill of caving.

The second comes later

finding the way out.

Each night the latest survey date

are typed into the computer

to produce an updated map.

The ancient skeleton

of a ring-tailed cat.

Kiym Cunningham examines

one of the riddles of Lechuguilla.

It's a mystery. I mean, altogether

it's a mystery how he got down here.

We're a thousand feet below

the surface.

Many vertical pits and long passages

to get here.

So, he was a heck of a caver!

He evidently died right on the margin

of this old pool system here,

so I would imagine possibly

he was alive when he was down here,

came to the pool to drink.

Only source of water he could find.

And maybe the mineral content

was very high.

It was not a good pool to drink from

and that may have been what killed him

The amount of carbon dioxide

in the cave atmosphere is measured.

If the level down here

is the same as on the surface,

it could indicate other openings

yet to be discovered.

Somewhere within the cave's vast system

the air is being disturbed.

There is noticeable movement.

Still, Lechuguilla refuses to yield

its secrets easily.

It remains alien

and strangely beautiful,

a landscape from another world.

Lechugulla's wonder is a fragile thing

What man can discover,

he can easily destroy.

Most of us may never see

these enchanting caverns

and others that lie still undiscovered.

But perhaps it will be enough to know

that they are there.

Lechuguilla now consists

of almost 60 miles

of breathtaking passageways.

New discoveries continue

and there is no end in sight.

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