This is a volcanic ridge.

But 10 miles down the ridge...

But the actual sub adult at 65 percent had no crest at all.

This is what in the infantry we used to call the military crest.

The climbers got on the southeast ridge.

Is this the bus for Park Ridge?

It's sort of surfing on a magnetic field at the crest of a wave.

And there were climbers on that summit ridge.

This is the view looking at the southeast ridge.

This is a view taken along the summit ridge.

39 percent of homes on Pine Ridge have no electricity.

We worry about cocaine coming from the Andean Ridge north.

OK, this is a view taken on the summit ridge itself.

The mid ocean ridge runs around like the seam on a baseball.

This is all you've got. You're very exposed on the summit ridge.

Unemployment on the Pine Ridge Indian Reservation fluctuates between 85 and 90 percent.

This is what a real one looks like, on the Juan de Fuca Ridge.

We're going to look at the mid ocean ridge, a 40,000 mile long mountain range.

Both Denmark and Russia have been devoting significant resources to exploring the Lomonosov Ridge. Denmark has hired Swedish icebreakers for repeated expeditions, and Russia has been deploying special submarines to obtain samples from the ridge and the ocean floor.

Her name is Pam Moran in Albemarle County, Virginia, the foothills of the Blue Ridge Mountains.

The tuberculosis rate on Pine Ridge is approximately eight times higher than the U.S. national average.

Because it's along the axis of the mid ocean ridge where the great crustal plates are separating.

What looks like a cloud behind the summit ridge is actually snow being blown off the summit.

The mid ocean ridge is a huge mountain range, 40,000 miles long, snaking around the entire globe.

How to assess countries claims to Arctic territory hinges on the status of the Lomonosov Ridge, a vast formation that rises from the sea floor and stretches 1,800 kilometers from Greenland to the East Siberian continental shelf. Everyone agrees that it is a ridge.

We're in 17th century Japan on the west coast, and a little, wizened monk is hurrying along, near midnight, to the crest of a small hill.

If you want to stop a sand dune from moving, what you need to make sure to do is to stop the grains from avalanching over its crest.

And the climbers up on the ridge were that much higher, 2,000 feet higher, and completely exposed to the elements.

Todd and Pete got up to the summit ridge, up in here, and it was a scene of complete chaos up there.

The Pine Ridge Reservation, the subject of today's slide show, is located about 75 miles southeast of the Black Hills in South Dakota.

And this kind of life and death of hydrothermal vent communities is going on every 30 or 40 years all along the ridge.

So we got out and walked, and sure enough, about half a mile, we came over the crest of this hill, and there was a huge gathering of Bedouin with their camels.

There's a ridge right in the middle of the picture, up above where that arrow comes in, that shows you that a little bit.

In 1994, Oak Ridge National Laboratory in Tennessee completed production of all the iridium parts that will be used to encapsulate the Pu 238 fuel.

OK. Those climbers were up near the summit, along that summit ridge that you see up there, and I was down here in Camp Three.

Of course, when you're on the ice, you only ever see one obstacle at a time, whether it's a pressure ridge or there's a bit of water.

And it's kind of cool if you look at the cassowary, or any of the birds that have crests on their heads, they actually grow to about 80 percent adult size before the crest starts to grow.

But if you were to put it on an equal area projection, you'd see that the mid ocean ridge covers 23 percent of the Earth's total surface area.

And we're over the Atlantic that's the ridge right there but we're going to go across the Caribbean, Central America, and end up against the Pacific, nine degrees north.

And he showed that if you were to take a baby and an adult and make an average of what it should look like, if it grew in sort of a linear fashion, it would have a crest about half the size of the adult.

It should not be. Until one of my colleagues said, It looks to me like a thermal blister, and the mid ocean ridge must be a cooling curve. We said, Let's go find out.

We began to introduce that in our explorations, and we continued to make phenomenal discoveries with our new robotic technologies. Again, looking for something else, moving from one part of the mid ocean ridge to another.

At Battery Park, on Manhattan s south end, the surge height reached 4.2 meters, flooding homes and businesses and plunging millions into darkness. Waves also reached extreme heights, with a buoy near the entrance to New York Harbor measuring a peak wave ten meters high, from crest to trough.

But on Pine Ridge, I will always be what is called wasichu, and wasichu is a Lakota word that means non Indian, but another version of this word means the one who takes the best meat for himself.

But we're just going to zip right past this area, this area that includes about 95 percent of the living space on our planet and go to the mid ocean ridge, which I think is even more extraordinary.