If Rocks Could Talk



Rondi: Now let's meet everyone's favorite tough guy,  Granite ! You've probably seen granite around before. This strong, sturdy rock is often used in buildings. But this granite has a special history. It traveled a very long way from its home before he was discovered.

Granite sitting on a pedestal

Granite: Yo, Rondi. You want me to tell the story?

Rondi: Yes, that would be great.

Granite: I'll start from the beginning. About two billion years ago, I formed from melted rock, or magma.

Rondi: And that makes you an igneous rock!

Granite: Hey, know a lot ... for a human. Now, I may be an  igneous rock , but I didn't erupt at the Earth's surface. I was formed about eight kilometers (5 miles) underground in a pocket of magma. Over thousands of years, the magma cooled into a solid. In fact, I cooled so slowly that I had time to grow these large crystals.

Rondi: Very nice. And I love all the different colors—gray, white, black, even pink ...

Large flat glacier.

Granite: Thanks! As I was saying ... Over millions of years, the rocks above me wore away from wind, water, and the slow movement of Earth's crust. After a while, I finally came to the surface. Then, many thousands of years ago, I was picked up by a giant glacier moving across the land.

Rondi: I bet that happened during the last ice age, about 20,000 years ago. 

Granite: You betcha! Earth's climate was much cooler then.  And enormous ice caps stretched far from the North and South poles.  

Rondi: How did you end up at the bottom of the ocean?

Granite: When the glacier finally started to melt, it dropped me and I sunk to the deep-sea floor. You know, it's pretty cold and dark down there. But it's not like I was scared or anything...

Rondi: Wow. That must have been some journey.

Granite: It wasn't easy. I was tumbled around a lot against ice and other rocks. Actually, all that grinding made me round. I tell ya, a lot of rocks wouldn't have made it that far. They would've crumbled from the wear and tear.

Close-up of granite interior spotted with a dark crust.

Rondi: I hope you don't mind my asking, but what's that black crust all over you?

Granite: I don't mind at all. It took me years to build it up.

Rondi: But where does it come from?

Granite: It's a layer of manganese I got from being on the ocean floor all that time. It comes from underwater volcanoes.

Rondi: How in the world did you get from the middle of the ocean to the Museum?

Granite: Scientists on a ship in the Atlantic Ocean were collecting rock samples from the ocean floor . They were surprised to see a piece of rounded granite that far from land. After all that time in the ocean, I'm glad to be back on land. I feel like I'm finally home.

Rondi: You know, you really are pretty nice under that tough exterior.

Granite: Aw, shucks, Rondi. Just keep it under your hat.

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Photos: All images: courtesy of AMNH