Earth Science: Classification of Rocks

Study Notes

Rocks are naturally occurring solid aggregates of minerals, occasionally including non-mineral solid particles.
The transformation of rocks into different types occurs through the rock cycle.

Definition: Formed from the cooling and solidification of magma or lava.
Types:
- Intrusive Igneous Rock: Formed from the solidification of magma beneath the Earth's surface, characterized by large mineral crystals.
- Extrusive Igneous Rock: Formed from the solidification of lava on the Earth's surface, often glassy in appearance or vesicular (having small holes).

Clastic Sedimentary Rock: Originates from the mechanical weathering debris of other rocks.
Chemical Sedimentary Rock: Forms from dissolved materials that precipitate from a solution.
Organic Sedimentary Rock: Composed of the accumulation of plant or animal debris.

Derived from "parent rocks" subjected to heat and pressure, leading to significant physical or chemical changes.

Foliated Metamorphic Rock: Displays banding (foliation) due to pressure-induced compression.
Nonfoliated Metamorphic Rock: Lacks foliation, presenting a more uniform composition.

Weathering and Erosion:
- Weathering: Breakdown of rocks into smaller particles.
- Erosion: Wearing away and transportation of earthen materials by natural forces such as wind, water, or ice.
Compaction and Cementation:
- Compaction: Sediments are compressed under the weight of overlying layers.
- Cementation: New minerals form and bind sediment grains together, solidifying the rock.
Metamorphism:
- Under extreme heat and pressure, rocks undergo transformation, sometimes melting slightly.
Melting of Magma:
- The process where solids convert to molten rock (magma).
Crystallization of Magma:
- Formation of rock crystals as magma cools and solidifies.