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VOLCANOES
Lesson 2 - Page 3

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Some rocks can tell you of their strange evolution. The picture to the right shows "pillow lava" forming. The water cools the crust of the lava quickly giving it a crust that curls into itself. It looks like many pillows stacked on one another. When you see pillow lava, a geologist knows that the eruption occurred under water.

Scoria is a vesicular rock due to the escape of volcanic gases during an eruption. Scoria is usually black with a high iron content, but also has a distinct reddish color due to a chemical reaction with oxygen in our atmosphere.


Pillow lava


Scoria

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