NOVA

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Narrator

This place is a paradise for geologists. And one of our national treasures. It is of course, the Grand Canyon. (uplifting music) That is a big hole. And it gets me every time. Wow, this is absolutely awesome. The landscape is breathtaking and so much more. As a geologist, the grand Canyon is perhaps the best place in the world, it's this incredible 300 mile long slice through the earth. And you can see layer after layer after layer, after layer of sedentary rock. (uplifting music) Each layer is a time capsule with a slice of our continent's epic history locked inside, stretching hundreds of millions of years into the past. Every single one of these layers tells its own story about what North America was like when that layer was deposited. So here in one place, you have this incredible story of our continent laid out for your viewing pleasure. (dramatic orchestral music) But to really tell that story I've got to step out of my comfort zone. So you're ready for a little time traveling? (glass shatters) I'm going to repel down the cliff to get up close and personal with these rocks. (dramatic rock music) I'm good to like step off the edge of the Grand Canyon. I can't believe I'm doing this. I really don't like the fact you put a cactus right here. (intense music) This is the moment of truth. Oh! It's just not the easiest thing to do, especially at a hundred degree heat, but it's worth it. Every foot I descend takes me further back in time. The first layer you come to in this part of the Canyon is this pinkish rock I'm hanging next to you right now. It's called the Esplanade layer and like all the rocks in the Grand Canyon, it's an ancient landscape frozen in time. (rock crackling) (rock rumbling) 300 million years ago, this place and all of the American Southwest was a vast sea of sand. Hot dry winds sculpted an immense desert landscape of endless dunes. Over time, the sand compressed and transformed into the sandstone that forms the top ledge of the Grand Canyon here today. Further down there's evidence of a very different landscape. About a thousand feet below the rim of the Canyon, the rock changes to limestone loaded with fossils. I've got a little fossil coral on my hand. It's fossils like this that tells us that this whole landscape was once under water. (uplifting music) (water splashing) 340 million years ago a warm, shallow sea covered all of the American Southwest. It's waters were teaming with trillions of microscopic marine organisms. When they died, their skeletons piled up on the sea floor and compressed into limestone, forming layers that are hundreds of feet thick. (dramatic orchestral music) And so it goes, layer after layer of rock telling us the story of long lost landscapes. Each one, once the surface of our continent. (ominous music)