RocksRocks

Combinations of different minerals

Granite is a mixture of:FeldsparQuartzMica

Hornblende

RocksRocks

Rocks are made up of a mixture of Rocks are made up of a mixture of minerals:minerals:

1. They can be formed in many 1. They can be formed in many different ways.different ways.

2. Rocks come in many different 2. Rocks come in many different shapes and colors.shapes and colors.

3. The components are not in any 3. The components are not in any fixed proportion.fixed proportion.

Types of RocksTypes of Rocks

IgneousIgneous

SedimentarySedimentary

MetamorphicMetamorphic

The Rock CycleThe Rock Cycle

Model that shows how one kind of rock changes Model that shows how one kind of rock changes into another kind of rock.into another kind of rock.

The diagram of the rock cycle shows how the The diagram of the rock cycle shows how the earth's rocks are changed again and again.earth's rocks are changed again and again.

Has no beginning and no end, rocks are Has no beginning and no end, rocks are continually changing from one form to another.continually changing from one form to another.

The changes that take place in the rock cycle The changes that take place in the rock cycle never destroy or create matter. The elements never destroy or create matter. The elements are just distributed in other forms.are just distributed in other forms.

Heat and Pressure

Weathering, Erosion, and Deposition

Compaction and Cementation

Weathering, Erosion, and Deposition

Cooling and Crystallization

Melting

Heat and Pressure

Sedimentary Rock

Metamorphic RockIgneous Rock

Sediment

Magma

Weathering, Erosion, and Deposition

Rocks are changed by Rocks are changed by processes such as:processes such as:

WeatheringWeathering ErosionErosion DepositionDeposition CompactionCompaction CementationCementation CrystallizationCrystallization Heat and PressureHeat and Pressure MeltingMelting

WeatheringWeathering

The breaking down of solid rock by The breaking down of solid rock by chemical or physical forces. chemical or physical forces.

Results in small particles and/or new Results in small particles and/or new chemicals.chemicals.Example:Example:

- Physical change – Some of the mineral matter in mountains is - Physical change – Some of the mineral matter in mountains is broken off by wind, water, or ice but otherwise remains the broken off by wind, water, or ice but otherwise remains the same.same.

- Chemical change – Some of the mineral matter is carried away - Chemical change – Some of the mineral matter is carried away in streams as individual particles we cannot see. These particles in streams as individual particles we cannot see. These particles are free to react with other particles to produce new minerals.are free to react with other particles to produce new minerals.

ErosionErosion

When weathered particles are carried When weathered particles are carried (transported) by agents of erosion, (transported) by agents of erosion, such as wind, water, ice, or gravity.such as wind, water, ice, or gravity.

DepositionDeposition

When weathered material is laid When weathered material is laid down, generally in layers, in a new down, generally in layers, in a new location.location.

CompactionCompaction

When deposited particles are When deposited particles are compressed into smaller volume.compressed into smaller volume.

Cementation Cementation

When the deposited particles are When the deposited particles are “glued” together by a cementing “glued” together by a cementing agent or by pressure.agent or by pressure.

CrystallizationCrystallization

When liquid rock (magma or lava) When liquid rock (magma or lava) freezes into a solid form.freezes into a solid form.

Heat and pressureHeat and pressure

Created by deep burial or by close Created by deep burial or by close contact with molten rock (lava or contact with molten rock (lava or magma).magma).

MeltingMelting

Changing a solid into a liquid by Changing a solid into a liquid by heat/pressure.heat/pressure.

Igneous RocksIgneous Rocks

The most abundant type of rock on The most abundant type of rock on Earth.Earth.

Most igneous rocks are produced Most igneous rocks are produced deep underground by the cooling and deep underground by the cooling and hardening of magma.hardening of magma.

Classification of Igneous Classification of Igneous RocksRocks

Classified according to how the Classified according to how the magma cools and hardens magma cools and hardens (crystallizes).(crystallizes).

CompositionComposition-refers to the minerals -refers to the minerals that make up the rock.that make up the rock.

TextureTexture-shape, size, arrangement -shape, size, arrangement and distribution of minerals that and distribution of minerals that make up the rock.make up the rock.

CompositionComposition

ExtrusiveExtrusive- Formed from lava; volcanic- Formed from lava; volcanic

IntrusiveIntrusive- Formed deep within the earth; - Formed deep within the earth; plutonicplutonic

Obsidian Pumice

Granite

Intrusive vs. Extrusive RocksIntrusive vs. Extrusive Rocks

Intrusive – Magma solidifies deep within the Intrusive – Magma solidifies deep within the earth. The slow cooling causes large crystals earth. The slow cooling causes large crystals to form and the texture is coarse-grained.to form and the texture is coarse-grained. Think: INside. Formed inside the earth.

Extrusive – Magma flows to the surface (now Extrusive – Magma flows to the surface (now called lava) and cools very rapidly. This called lava) and cools very rapidly. This rapid cooling causes small or no crystals to rapid cooling causes small or no crystals to form and the texture is fine-grained. form and the texture is fine-grained. Think: EXit. These rocks exited the Earth

TexturesTextures GlassyGlassy

Fine-grainedFine-grained

Coarse-grainedCoarse-grained

PorphyriticPorphyriticObsidian Granite

Granite

Basalt

Gabbro vs. Basalt

Diorite vs. Andesite

Granite vs. Rhyolite

Sedimentary RocksSedimentary Rocks

Forms from cementing together of Earth’s Forms from cementing together of Earth’s materials called sediment (clay, sand, materials called sediment (clay, sand, pebbles, gravel, plants or animal remains).pebbles, gravel, plants or animal remains).

75% of the rocks at Earth’s 75% of the rocks at Earth’s surfacesurface are are sedimentary rocks.sedimentary rocks.

Sedimentary rocksSedimentary rocks can be categorized into can be categorized into three groups based on sediment type.three groups based on sediment type.

ClasticsClastics

ClasticClastic rocks are composed of grains or rocks are composed of grains or fragments of rocks and minerals that have fragments of rocks and minerals that have been eroded, transported, deposited, and been eroded, transported, deposited, and cemented together.cemented together.

During the transport process, the particles During the transport process, the particles that make up these rocks often become that make up these rocks often become rounded due to abrasion or can become rounded due to abrasion or can become highly sorted. highly sorted.

Non-clasticsNon-clastics

Non-clastic rocks are created either Non-clastic rocks are created either from chemical precipitation and from chemical precipitation and crystallization, or by the lithification crystallization, or by the lithification of once living organic matter. of once living organic matter.

IdentificationIdentification of non-clastics requires of non-clastics requires identification of the primary mineral.identification of the primary mineral.

Classification of Classification of Sedimentary RocksSedimentary Rocks

Clastic (fragmental) – formed from the Clastic (fragmental) – formed from the broken pieces of other rocks (clastics).broken pieces of other rocks (clastics).

Organic – forms from accumulation of Organic – forms from accumulation of dead plants and animals.dead plants and animals.

Chemical Chemical – form when dissolved – form when dissolved minerals precipitate out or are left minerals precipitate out or are left behind when a solution evaporates.behind when a solution evaporates.

Clastic RocksClastic Rocks ConglomerateConglomerate

SandstoneSandstone

ShaleShale

Organic RocksOrganic RocksOrganic rock comes remains of plants and animalsOrganic rock comes remains of plants and animals

Coquina Fossiliferous Limestone

Chemical RocksChemical RocksChemical rocks come from minerals that are Chemical rocks come from minerals that are

dissolved in a solution and crystallizedissolved in a solution and crystallize

LimestoneLimestone

Metamorphic RocksMetamorphic Rocks

Formed when high heat and pressure Formed when high heat and pressure changes the original or parent rock changes the original or parent rock into a completely new rock. into a completely new rock.

The parent rock can be either The parent rock can be either sedimentary, igneous, or even sedimentary, igneous, or even another metamorphic rock.another metamorphic rock.

Metamorphic RocksMetamorphic Rocks

Metamorphic means “change in form”.Metamorphic means “change in form”. Two categories:Two categories:

1)1) Regional Metamorphism – the deeper a layer Regional Metamorphism – the deeper a layer of rock lies within the earth’s crust, the more of rock lies within the earth’s crust, the more it will be affected by temp and pressure.it will be affected by temp and pressure.

2)2) Contact Metamorphism – common in regions Contact Metamorphism – common in regions of volcanic activity since hot magma may of volcanic activity since hot magma may heat the preexisting rock layers.heat the preexisting rock layers.

FoliatedFoliated

When mineral grains flatten and line up in When mineral grains flatten and line up in parallel layers.parallel layers.

Light and dark bands.Light and dark bands.

UnfoliatedUnfoliated

The mineral grains The mineral grains

change, grow and change, grow and

rearrange but theyrearrange but they

don’t form bands.don’t form bands.