To understand what the coastline might look if Earth’s climate continues to warm, paleontologist Kirk Johnson and geologist Maureen Raymo search for 3-million-year-old clams in a Virginia quarry miles inland.
What did the East Coast Look Like 3 Million Years Ago?
Published: February 5, 2020
Kirk Johnson: Lots of white crumbly stuff in here.
Maureen Raymo: Yeah.
Johnson: Geologist Maureen Raymo studies places like this to try to predict what a warmer climate might have in store.
Raymo: Super cool.
Johnson: They didn’t build rock hammers for digging in clay, I’ll tell you that much. To find what Maureen’s looking for, we need to dig deeper, and my rock hammer just isn’t going to cut it.
Raymo: Digging tool of choice?
Johnson: Yeah. Beats a shovel doesn’t it?
Johnson: We’re trying to reach a layer of mud that dates back 3,000,000 years. Can you bring a chunk of that black stuff up from the bottom? We’ll just dump it on this side. Just like a little scoop? Oh, yeah. Look at that.
Raymo: Every geology department should have one.
Johnson: Thanks to the backhoe, we hit a fossil jackpot.
Raymo: Hey, thanks.
Johnson: That’s perfect. Look at this.
Raymo: That’s awesome.
Johnson: Ooh! Look at that. That’s a perfect 3,000,000-year-old clam, right there.
Raymo: Oh, man, that could have been, like, alive yesterday.
Raymo: That’s beautiful.
Johnson: Ah, places like this are pretty special for paleontologists. This is great.
Raymo: Yeah, a window to the past.
Johnson: We’re on a beach.
Raymo: We’re on a beach 3,000,000 years ago.
Johnson: It’s incredible to think that this quarry, 90 miles inland today, was once a beach, teeming with corals and other marine life. There was warm ocean water lapping against this shore.
Raymo: Warmer world, warmer fossils, coral reefs. It’s amazing. It’s right before we slid into the ice ages.
Johnson: It’s just solid black mud, full of clams. Three million years ago, when the Earth was three or four degrees warmer, the North was mostly ice free. A lot of the water that is now locked up in glaciers was in the ocean, which means the global sea level was about 60 feet higher. According to Maureen’s calculations, this is how the East Coast would have looked. If Earth continues to warm, the coastline will start moving inland, as the ocean returns to places it covered long ago.
Johnson: It doesn’t seem like much, but it gets you back to a time when you had shorelines that were 80 miles further inland.
Johnson: Three million years ago is the last time the CO2 in the atmosphere was as high as it is today, over 400 parts per million.
Raymo: This is our window into our future.
Johnson: So, how come our present sea level isn’t right here now?
Raymo: The ice sheets are out of equilibrium with the atmosphere right now. The atmosphere’s warming, we’re adding more CO2 every year. You could think of them like a frozen lasagna you’ve put in a preheated oven, you know? And the oven is our atmosphere, warmer, and the ice sheets are melting just like the lasagna would slowly melt, and it takes a while.
Johnson: So, in the same way the lasagna’s eventually going to be ready to eat, we’ll eventually have higher sea levels.
Raymo: We will.
Johnson: So, the real question is how long it takes for the ice sheets to melt in these conditions, right?
Raymo: Exactly. That’s the question that is driving research all over the world.
Director: Lucy Haken
Assistant Producer: Sacha Thorpe
Camera: Piers Leigh
Sound: Josh Forwood
Digital Producer: Sukee Bennett
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