This is a volcanic ridge.

But 10 miles down the ridge...

The climbers got on the southeast ridge.

Is this the bus for Park Ridge?

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.

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.

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.

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.

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.

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.

The North East Atlantic Fisheries Commission (NEAFC) agreed on an interim prohibition of fishing with gear which adversely affects the seabed on a number of seamounts and in a section of the Reykjanes ridge for a three year period.

Now, if any of you have ever heard of AIM, the American Indian Movement, or of Russell Means, or Leonard Peltier, or of the stand off at Oglala, then you know that Pine Ridge is ground zero for Native issues in the U.S.

But for the time being, neither Santa Claus, nor anyone else, has reason to be worried. The nature of the Lomonosov Ridge will be debated for years to come, while his thoughts and ours are likely to be focused on more immediate issues.

What happens is that the wind blows the sand up the shallow slope on the other side, and then, as each sand grain hits the top of the ridge, it cascades down on the inside of the crescent, and so the whole horn shaped dune moves.

Within the hippocampus a curved elongated ridge located in each of the brain's two temporal lobes is a structure called the dentate gyrus, which produces new neurons throughout adult life. Chronic stress inhibits neurogenesis and also causes many hippocampal neurons to shrink a process called remodeling.

In one of them, one of the kids once said, When we were riding on this ridge overlooking the Dead Sea and he's talking about this spot here I was reminded of the day when I left my village in Ethiopia and went away together with my brother.

Seven countries (Canada, China, Denmark, Norway, South Africa, the United States of America and Yemen) and five organizations (Eurostat, the International Atomic Energy Agency, the International Energy Agency, the Oak Ridge National Laboratory Carbon Dioxide Information and Analysis Center and the Department of Economic and Social Affairs) participated.

Still others blame changes in policy and practice. Lands legally recorded as wilderness will encourage more fire and a reluctance to put firefighters at risk in remote settings as well as cost concerns argues for backing off and letting the next ridge burn while offering point protection for threatened communities.

Aaron Huey's effort to photograph poverty in America led him to the Pine Ridge Indian Reservation, where the struggle of the native Lakota people appalling, and largely ignored compelled him to refocus. Five years of work later, his haunting photos intertwine with a shocking history lesson in this bold, courageous talk from TEDxDU.