(music)
- Wow.
Oh hey Fernando.
Where are we?
- Hello John.
This large area here at Blanchard Springs Cavern
is called the Grand Canyon.
Remember the little trickle of water we saw earlier?
Well, it's been joined by more and more trickles of water
moving through the rock
to create this large and beautiful underground river.
Like we said, caves form over millions of years.
Here in Arkansas, caves form in limestone rock.
Water moves from the surface, as we saw,
through cracks and porous spaces in the rock.
Surface water starts out slightly acidic
and can pick up acid from microbes in the soil
as it moves down into the subsurface,
creating caves and larger pathways for water to flow.
As you said above ground,
these areas are known as karsts,
a word from a beautiful area in Virginia
where this was first described.
- As groundwater dissolves limestone,
it picks up calcite,
the building block of most cave formations like these.
How water moves determines what shape
these formations take.
The one thing for sure is that
they take millions of years to form.
Here at Blanchard it takes about 150 years
for one cubic centimeter of calcite to deposit,
which is about the size of an almond.
- 150 years to grow the size of an almond?
That's going to make this taste even better.
What?
You didn't want one did you?
- So cave formations like
stalactites and stalagmites, right?
- Hey actually I have a good way
to remember these formations.
Stalactites are the ones that hang tight to the ceiling,
and stalagmites might grow big and tall one day.
- That's right Amtchat.
They give us some clues about how this cave
and the world around it might have looked in the past.
- As you've learned,
caves have relatively stable microclimates that
make them ideal to record the local climate of the cave.
As I mentioned,
this cave formed from water coming down from up above,
but some caves form through water
moving up from below, or a combination.
Some caves form completely differently
in other types of rock.
Like lava tubes in places like Oregon,
Washington, or Hawaii.
Caves can form along coastlines as sea caves
through the mechanical erosion caused by wind and waves.
Or they even form in glaciers.
These types of areas are called pseudo-karsts
because they don't form through dissolution
like caves in limestone, marble, or dolomite.
- So why and how exactly do you map caves?
- I work with the Cave Research Foundation
and we map caves so we can understand how they form
and where the water flows.
This team here is working on mapping a cave right now.
They use a laser, called a disto, to measure distances.
- 9.3 meters.
- And an inclinometer to measure
vertical extent of the cave.
So you can hear them calling out measurements
and Fernando is the sketcher.
He is making an actual 3-D sketch of the cave on paper.