Volcanic Rocks & Landforms

Eruptling — Volcanic Rocks & Landforms Obsidian Mirror Room

Hi, explorer! Eruptling here, in Obsidian Mirror Room.

I keep our volcanic rock records in this imaginary archive.

The Grumblies mixed up their histories. Let's investigate together!

When lava cools and solidifies, it becomes igneous rock.

A fresh flow can become a solid rocky surface.

Its outside may cool while material underneath remains hot.

That's why we study supplied records instead of approaching fresh flows.

Basalt is a common volcanic rock.

Its crystals are often too small to see easily.

Faster cooling usually gives crystals less time to grow.

Crystal size can offer clues about a rock's cooling history.

Obsidian is volcanic glass, rather than a collection of visible crystals.

Suitable lava can form obsidian when it cools very quickly.

The lava's composition matters, too. Not every flow makes obsidian.

Our shiny story room reminds me to compare surfaces carefully.

Shine alone doesn't explain an entire rock's history!

Repeated eruptions can build up layers of volcanic material.

A later lava flow may cover an older solid flow.

Over time, repeated additions can build a volcano.

Fluid lava can spread far and build broad, gently sloping shapes.

Many shield volcanoes have this broad shape.

Other combinations of lava and fragments can build steeper cones.

Volcanoes differ in size, shape, material, and eruption history.

A shape alone can't tell us every detail of past eruptions.

Scientists compare rock layers, textures, maps, and other evidence.

Our record shows new lava covering an older rock surface.

That supports a story of land building over time.

How could molten lava become the solid rock in our record?

Did it cool and solidify, or simply turn into soil?

Cooling and solidifying! Fresh volcanic rock isn't instant soil.

Great investigating! You followed how the material changed.

Which description fits obsidian: volcanic glass or fluffy burned wood?

Volcanic glass! Suitable lava cooled before many crystals could grow.

Cooling lava forms solid igneous rock.

Repeated eruptions can build layers, islands, and different volcanic shapes.

Our rock histories are clearer. The Grumblies missed these clues!

Bring your sharp observations. I'll help you through the adventure.

Train more, start this adventure, or choose another map destination.

Free Volcanic Rocks & Landforms teacher guide and practice (PDF)