Understanding the Rock Cycle and Rock Types

Magma

Molten rock found below the Earth's surface.

Lava

Molten rock that erupts onto the Earth's surface.

Intrusive Rocks

Igneous rocks that form from magma below ground; have large crystals and coarse-grained texture.

Extrusive Rocks

Igneous rocks that form from lava above ground; have small crystals and fine-grained texture.

Quick-Cooling Igneous Rocks

Rocks that cool too fast to form crystals; textures include glassy or vesicular (holes from trapped gas).

Erosion

The movement of sediment by wind, water, or gravity.

Deposition

When sediment settles in a new location after being moved.

Weathering

Breaking down rocks into smaller pieces.

Compaction

Layers of sediment are pressed together under weight.

Cementation

Sediment particles stick together, forming solid rock.

Clastic Rocks

Made from pieces of other rocks (e.g., sandstone).

Chemical Rocks

Formed from minerals crystallizing out of a solution (e.g., limestone).

Organic Rocks

Formed from remains of plants and animals (e.g., coal).

Regional Metamorphism

Rocks change over large areas due to high pressure and heat.

Contact Metamorphism

Rocks change due to heat from nearby magma.

Parent Rock

The original rock before it changes into a metamorphic rock.

Recrystallization

The process of crystals growing larger under heat.

Foliation

The alignment of minerals into bands or layers under pressure.

Non-Foliated Rocks

Rocks with no visible layers (e.g., marble).

Rock Cycle

The continuous process where rocks change between igneous, sedimentary, and metamorphic forms.

Melting

Turns rocks into magma.

Cooling

Magma or lava cools to form igneous rock.

Weathering and Erosion

Break down rocks into sediment.

Compaction and Cementation

Form sedimentary rocks.

Heat and Pressure

Transform rocks into metamorphic rocks.

Igneous rock

Formed from cooling and solidification of magma or lava

Sedimentary rock

Formed from compaction and cementation of sediments

Metamorphic rock

Formed from heat, pressure, or chemical changes

Coarse-Grained Texture

Slow cooling, large crystals (e.g., granite).

Fine-Grained Texture

Fast cooling, small crystals (e.g., basalt).

Glassy Texture

Extremely fast cooling, no crystals (e.g., obsidian).

Vesicular Texture

Holes from trapped gas (e.g., pumice).

Effect of Heat

Enlarges crystals (recrystallization).

Effect of Pressure

Causes minerals to align or rearrange.

Foliated vs. Non-Foliated

Foliated has Folds; Non-foliated has No Layers.

Clastic (sed) example

Sandstone

Organic (sed) example

Coal

Chemical (sed) example

Limestone

Foliation (meta) example

Gneiss

Non-Foliation (meta) example

Marble

Extrusive (ig) example

Obsidian

Intrusive (ig) example

Granite