03 Rocks and the Rock Cycle Free Online FlashCards

What are rocks, and how are they classified?

Rocks are naturally occurring aggregates of minerals or other materials, classified by how they formed: igneous, sedimentary, or metamorphic.

What distinguishes magma from lava?

Molten rock underground is magma; when it reaches Earth’s surface, it is called lava.

How does slow underground cooling affect igneous rock?

Intrusive igneous rocks cool underground. Slow cooling gives larger crystals time to grow, as in granite.

What texture commonly results when lava cools rapidly?

Extrusive rocks cool at or near the surface. Rapid cooling usually produces small crystals, as in basalt.

What can extremely rapid cooling of molten rock produce?

Extremely rapid cooling of molten rock can form volcanic glass, such as obsidian.

What processes turn deposited sediment into rock?

Sediment is buried, compacted as grains are pressed together, and cemented as they become bound. Compaction and cementation together are lithification.

What makes a sedimentary rock clastic?

Clastic rocks form from fragments of older rocks; sandstone is an example made from lithified sand-sized grains.

How do chemical sedimentary rocks form?

Chemical sedimentary rocks form when dissolved substances precipitate from water.

What material forms biologic sedimentary rocks?

Biologic sedimentary rocks form from accumulated remains of organisms.

What are strata, and what can they reveal?

Sedimentary rocks commonly form in layers called strata. Their layers, grain size, and composition can reveal what was deposited and how.

How does a rock become metamorphic?

Metamorphic rocks form when existing rocks are altered by heat, pressure, and sometimes chemically active fluids, without melting completely.

What causes contact metamorphism?

Contact metamorphism occurs when heat from nearby magma changes the surrounding rock.