If Rocks Could Talk

Deformed Conglomerate


Rondi: I'm pleased to present Deformed Conglomerate (con-GLOM-ur-it). This rock has been through it all. It knows what it's like to be a sedimentary rock, an igneous rock, and—in its current state—a metamorphic rock . Like many rocks, it has changed from one form to another over millions of years, in a process called the rock cycle.

Deformed Conglomerate sitting on a pedestal

Deformed Conglomerate: And it's not an easy process, Rondi. I have lots of aches and pains from going through it.

Graphic depicting the rock cycle, with arrows indicating how igneous, sedimentary and metamorphic rocks can transform into another type of rock.

Rondi: Why don't you tell us about the rock cycle?

Deformed Conglomerate: Sure thing, Rondi. You see, Earth is always recycling rocks, changing them from one type to another. Melted rock, or magma, forms igneous rocks. These rocks form underground or above ground.

Rondi: Can you give us some examples?

Visualization of an erupting volcano with bright lava emerging vertically from the volcano's opening.

Deformed Conglomerate: Sure! Granites form by cooling slowly underground. Volcanic rocks form when lava erupts from a volcano and cools quickly above ground.

Rondi: Then what happens?

Deformed Conglomerate: Over time, underground rocks are pushed up and exposed at the surface by the movement of Earth. Weathering like rain and wind breaks up these rocks into smaller pieces and deposits them in lakes and oceans. Over time, layers of sediment can become pressed to form sedimentary rock.

Rondi: How does that work?

Deformed Conglomerate: Sometimes, igneous and sedimentary rocks are buried deep in Earth. Extreme heat and pressure can change them into metamorphic rocks. If the heat becomes really intense, rocks can even melt to form magma.

Rondi: Which is how they all started.

Deformed Conglomerate: And the cycle begins again! It makes me hurt all over just to think about it.

Rondi: So, you’re saying any rock you find may have once been another kind of rock, or is made from pieces of other rocks. And that rock could change again.

Deformed Conglomerate: Conglomerate: That's right. It takes millions of years, but rocks are recycling all the time. Imagine what our planet would be like if it just kept making new rocks, but didn't recycle the old ones! It just goes to show how important it is to recycle everything you can, from aluminum cans to plastic bags.

Rondi: Could you tell us about your unusual name?

Deformed Conglomerate: It's nice, isn't it? "Deformed Conglomerate" just rolls off the tongue. My name fits me perfectly. You see, a "conglomerate" is a mix of different things. And that's me, all right. If you take a closer look, you'll see I have many wavy patterns of different colors, textures, and grain sizes.

Close-up of a layered, textured dark colored rock with light colored blobs.

Rondi: By the way, what are those white blobs?

Deformed Conglomerate: Those were once igneous rock that erupted from a volcano. Like many rocks on Earth’s surface, they were worn down into pebbles over time.

Rondi: If it’s not too personal a question, how did they get inside you?

Deformed Conglomerate: I’m happy to tell you. My pebbles ended up in a stream with other sediments like sand and silt. And you know what happens when sediments build up and become compacted.

Rondi: Sedimentary rock is formed.

Deformed Conglomerate: That's right. I turned into a conglomerate rock. But my story doesn't end there—as if I hadn't been through enough already! After many more years, I was buried under a mountain. This happened because pieces of Earth's crust, called tectonic plates, collided together to form a mountain range.

Rondi: I can't imagine the heat and pressure you must have been under.

Deformed Conglomerate: You're not kidding. My layers of sediment were squished into wavy patterns. The pebbles of igneous rock were harder to crush, but they were still flattened. Let me tell you, becoming a metamorphic rock is hard work. After that experience, I was warped. I was distorted. I was ...

Rondi: ... "deformed"?

Deformed Conglomerate: Exactly! And that's how I got my name, "Deformed Conglomerate."

Rondi: So you've been through the whole rock cycle! I wonder what would have happened to you if you hadn't been picked up by scientists?

Deformed Conglomerate: Who knows! I could have been broken up into smaller pieces by wind and rain, then compacted again into sedimentary rock. If I ended up under another mountain, I may have gotten squished all over again into a different metamorphic rock.

Rondi: Or you could have been buried so deep that you would have melted and eventually been formed into igneous rock.

Deformed Conglomerate: It's exhausting just to think about it.

Rondi: Well, we're glad you ended up here.

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Image Credits:

All images: courtesy of AMNH