ROCKS

Rocks

a naturally occurring solid mixture composed of minerals, smaller rock fragments, organic matter, or glass.

Grains – individual particles in rock

Types of Rocks

Igneous – most abundant on Earth

Formation○ Molten rock (magma) erupts

onto the earth (lava) and cools

Texture/Composition○ Fine-grained (small crystals)○ Coarse-grained (large crystals)

Types of Rocks

Sedimentary

Formation○ Lithification – process through which sediment

(loose rock and mineral fragments) turn into rock○ Layers of sediment build up and the weight of top

layers compact the sediments into rock

Texture/Composition○ Fine or coarse grained○ Rounded (older) or angular (younger)

Types of Rocks

Metamorphic

Formation○ Parent rocks are squeezed or heated forming

new rocks

Texture/Composition○ Foliation – uneven pressures cause flat

minerals to line up, giving the rock a layered appearance

Uses of Rocks

Hard and durable (granite, limestone)construction, building

Soft with hard pieces (pumice)polishing/cleaning

Foliated (slate)roofing shingles

Soft (marble)carving/sculpturing

The Rock Cycle

Series of processes that continually change one type of rock into another

Processes of the Rock Cycle Cooling and Crystallization

Extrusive Rock – igneous rocks that form from lava that erupts, cools, and crystallizes on Earth’s surface

Intrusive Rock – igneous rocks that form from magma that cools and crystallizes inside Earth

Processes of the Rock Cycle Uplift

Process that moves large amounts of rock up to the Earth’s surface

Associated with development of mountains

Weathering and ErosionBreaking down and transporting of rock due to

the environment (wind, glaciers, rain, organisms)

Processes of the Rock Cycle Deposition

Process of laying down sediment in a new locationForms layers of sediment

Compaction and CementationWeight of overlying layers pushes grains of

sediment closer togetherCrystallized minerals cement the grains together

Processes of the Rock Cycle Temperature and Pressure

Rocks under high temperatures and pressures undergo metamorphism

High enough temperatures cause the rocks to melt into magma to become igneous again

Rocks and Plate Tectonics Most changes to rocks occur at tectonic

plate boundaries (volcanoes, mountains, earthquakes, etc.)