ROCKS Types of Rocks and How they Change

Learning Targets: 1.Describe how igneous rocks form 2.Describe the properties of some common types of igneous rocks 3.Relate some common uses of igneous rocks

Rocks and Minerals 1.Rocks = minerals bound together 2.Usually have many types of minerals 3.Mineral grains will vary in size and can be used to identify the rock and how it was formed

Types of Rock 1.Igneous: cooling of magma 2.Sedimentary: compaction and cementation of other rocks and minerals 3.Metamorphic: existing rock is changed by heat or pressure

IGNEOUS ROCK: GRANITE

SEDIMENTARY ROCK: SANDSTONE

METAMORPHIC ROCK

Igneous Rocks 1.Formed by crystallization a)Molten rock cools and solidifies 2.Largest source of new minerals 3.Most rock is igneous a)Over 700 types

Crystallization 1.Intrusive: cools, solidifies and forms minerals below the surface a)Intrusive = Interior 2.Extrusive: cools, solidifies and forms minerals on or above the surface a)Extrusive = Exterior

Intrusive Igneous 1.Crystallization occurs slowly a)Cool slowly  large minerals e.g. Granite 2.May remain below the surface or be exposed by erosion or uplifting a)Pluton: intrusive rock body that has cooled underground 3.Most common on the continents

Extrusive Igneous 1.Crystallization occurs quickly a)Cool quickly  small minerals  e.g. Basalt 2.Cools fast enough to give clues about how it was formed 3.Most common in oceanic crust

Sedimentary Rock 1.Formed by compaction and cementation a)Rock fragments b)Organic materials c)Chemical precipitates 2.Mainly created by the movement of water, but also wind and gravity

Sedimentary Formation 1.Weathering breaks rocks into small pieces (sediments) 2.Sedimentary rocks form in layers because sediment is deposited in thin layers 3.Layers give scientists a relative dating scale of Earth’s history. a)Bottom layers are older than top layers 4.Breaks in the pattern give clues about important events

Sedimentary Rock Formation 1.Lithification: accumulated sediments harden into rock a)Compaction: Crystals join due to pressure i.Driven by pressure b)Cementation: Fluids fill in the spaces between loose sediments and crystallize i.Driven by the flow of water

Metamorphic Rock 1.Igneous or sedimentary that have been changed by heat and pressure 2.Heat and pressure allow molecules to reconfigure themselves a)High heat  more motion b)Not hot enough to fully melt

Metamorphic Rocks 1.Metamorphism can change igneous, sedimentary, or metamorphic rocks into new rocks

Foliation 1.Different minerals react differently to heat and pressure 2.As minerals partially melt and recrystallize they often form bands of minerals in the rock called foliation a)Folio = book, leaves

Foliation 1.These bands DO NOT show relative age like sedimentary rocks 2.Can only develop when the pressure is from a single direction

Foliation

Metamorphic rocks often show banding

Types of Metamorphism 1.Regional metamorphism: changes caused by the application of extreme pressure over a large area 2.Contact metamorphism: changes caused by rocks coming into contact with extremely hot magma a)Does not completely melt the rock

Regional Metamorphism

Contact Metamorphism

Shale becomes Slate

Granite becomes Gneiss

Limestone become Marble

Sandstone becomes Quartzite

Layers of siltstone and mudstone become Hornfels