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242

deformed conglomerate

OLogy Series
geology
card
242

deformed conglomerate

OLogy Series
geology

Deformed conglomerate is a metamorphic rock that has been changed by heat and pressure. Its large, round pebbles are igneous rocks that were swept into the layers of sedimentary rock as they were forming. Then, the rock was buried in the Earth's crust. It was heated and squeezed until the pebbles and softer parts flattened into wavy patterns.

The wavy patterns have different bands of color because:

they have different amounts and types of minerals

the rock was formed in Alaska

heavy minerals appear darker

Are you right?

Correct!

Different bands of color contain different amounts and types of minerals. These layers formed when the rock was a sedimentary rock.

Which process best describes how deformed conglomerate forms?

rock is heated by magma inside the Earth

rock is changed by heat and pressure under a mountain

rock is formed when lava cools and hardens

Are you right?

Correct!

Deformed conglomerate is formed by extreme heat and pressure. This can occur in the Earth's crust, often under a mountain.

Ed Mathez, Earth scientist

The study of these rocks can tell geologists about the history of mountains, like when they formed, when they were eroded away, and how many times they were pushed up.

Once a rock becomes deformed conglomerate, it can never change into another kind of rock again.

Fact
or
Fiction
?

Fiction

Depending on the conditions the rock is under, it could someday become sedimentary or igneous rock, or even change into another type of metamorphic rock.

All metamorphic rock has wavy patterns from the heat and pressure.

Fact
or
Fiction
?

Fiction

Metamorphic rock can have bands, specks, or be the same color throughout. Its appearance depends on the minerals it's made of and the amount of heat and pressure it's been through.

Definition: a rock with large pebbles that has been transformed by heat and pressure
Type: metamorphic
Appearance: wavy layers of different colors and grain sizes
Grain size: large, squashed pebbles
Cool fact: Deformed conglomerate could be made from both igneous and sedimentary rocks.

Image credits: courtesy of AMNH; Ed Mathez: courtesy of AMNH.