THE ROCK CYCLE

What is the Rock Cycle?

The Rock Cycle

Defined: The process by which all rocks on Earth are formed and how basic Earth materials are recycled over time

Note: A very, very long time

The Rock Cycle

Sedimentary Rock

Metamorphic Rock

Igneous Rock

Three main types of rock on Earth

Igneous Rock: Forms from molten rock that cools and hardens either above or below Earth surface

Two Types: Intrusive/Extrusive Sedimentary Rock: formed either by pieces of

rock being bound together or by chemical precipitation

Two types: Clastic/Non clastic Metamorphic Rock: Form when any type of

rock is altered by the effects of heat, pressure, or chemical action

Two Types: Foliated/ unfoliated

Watch the Video and fill in this Chart! http://www.youtube.com/watch?v=U7YQ5vwaL98

Why does the Rock Cycle even exist?

DENSITY (again) When rock is heated up and melted

inside the Earth, it becomes hot liquid (magma) hot liquids are less dense then solid rock.

The magma moves up through any cracks or openings (volcanoes, fissures) until it reaches the surfaces. Then spreads out, cools, and turns solid.

Why does the Rock Cycle even exist? Cont’d After rock is formed, one of two

things will occur. 1. Rock will begin to erode into

small sediments and settle somewhere else on Earth’s surface (sedimentary)

2. That rock will cool, turn solid, and become more dense, where over a long time period, will begin to sink.

Thus causing a cycle!

Next time we will introduce Igneous Rocks, their formation, and types

IGNEOUS ROCKS Igneous Rock: Forms from molten

rock that cools and hardens either above or below Earth surface.

Igneous rocks are often defined by texture and chemical composition.

Igneous Rocks

Identification of igneous rocks factors Texture: The feel, appearance, or

consistency of a surface or a substance. (Simply what the rock type looks and feels like)

mineral and chemical composition: What minerals does the rock consist

of?

Igneous Rocks

Igneous Rocks are made from volcanic activity and form when magma or lava cools

Magma: Hot molten material INSIDE of the Earth’s surface

Lava: Hot molten material OUTSIDE of the Earth’s surface

MAJOR ELEMENTS PRESENT IN MAGMA

Oxygen, Aluminum, Iron, Magnesium, Calcium, Potassium, and Sodium.

Igneous Rocks by Physical and Chemical Characteristics Intrusive Igneous Rocks: Course-grained igneous rock that

cools slowly beneath the Earth’s surface.

Extrusive Igneous Rocks Fine-grained igneous rocks that cool

quickly on Earths surface overnight

Intrusive Igneous Rock

Cools and turns solid very, very slowly below the Earths surface. Typically have large crystals present in the rock due

to the slow cooling process.

Intrusive Igneous RocksGranite is a coarse-grained, light colored, intrusive igneous rock that contains mainly quartz and feldspar minerals. The specimen above is about two inches (five centimeters) across.

Diorite is a coarse-grained, intrusive igneous rock that contains a mixture of feldspar, pyroxene, hornblende and sometimes quartz. The specimen shown above is about two inches (five centimeters) across.

Extrusive Igneous Rocks

Fined grained (smooth) rock that cools quickly on Earth's surface. Cools quickly due to exposure to the atmosphere, interaction with water, etc.

Extrusive Igneous RocksBasalt is a fine-grained, dark-colored extrusive igneous rock composed mainly of plagioclase and pyroxene. The specimen shown is about two inches (five centimeters) across.

Hawaiian Islands

Obsidian is a dark-colored volcanic glass that forms from the very rapid cooling of molten rock material. It cools so rapidly that crystals do not form. The specimen shown above is about two inches (five centimeters) across.

Identifying Igneous Rock by Color

FELSIC and MAFIC Igneous Rock

Felsic: Light-colored Igneous Rocks. They are light in color due the minerals Feldspar and Silica being present in the mineral

Mafic: Igneous Rocks that are dark in color due to the presence of Magnesium and Iron

Overview of Identification of Igneous RocksIDENTIFICATIO

NDEFINITION EXAMPLE

S

Intrusive Cools and turns solid very, very slowly below the Earths surface. Typically have large crystals present in the rock due to the slow cooling process.

GraniteDiorite

Extrusive Fined grained (smooth) rock that cools quickly on Earth's surface

BasaltObsidian

Mafic Igneous Rocks that are dark in color due to the presence of Magnesium and Iron

ObsidianBasalt

Felsic Light-colored Igneous Rocks. They are light in color due the minerals Feldspar and Silica being present in the mineral

GraniteDiorite

Regents Scheme for Identifying Igneous Rocks

Sedimentary Rocks

2nd most Abundant type of rock in the Earth system.

Sedimentary Rocks

Defined:

Rocks formed either by rock fragments or organic matter being bound together or by chemical precipitation.

Formation of Sedimentary Rock Very cool process Sedimentary rocks formed over millions of

years. The form through a variety of processes beginning with Weathering and Erosion

Step one. Weathering: General process where rocks

are broken down at Earths surface to produce sediment particles

Erosion: The process of individual sediments being carried down hill.

Two Types of Weathering

Physical and Chemical Physical: occurs when solid rock is

broken into smaller pieces by mechanical process that does not change the chemicals in the rock

Chemical: Occurs when the minerals in a rock are chemical altered or disolved

Examples of physical weathering

Examples of Chemical Weathering

Formation of Sedimentary Rock

Weathering occurs when either rain, Ice, wind, or water, breaks down solid rock over time into small, individual sedimentsErosion: Sediments are carried from high energy to low energy areas. Typically occurs by water transporting the sediment down hill. Also by wind.

Transportation and Deposition Step two: Transportation: currents of wind and

water or the moving ice of glaciers transport sediment to new locations down hill or down stream.

Deposition: Occurs when sediment particles settle out as wind dies down, water currents slow, or glacier edges melt.

Step 3: Compaction and Cementation Compaction: Process of sediments

building up in layers on top of each other over time

Cementation: hardening of clastic sediments by the precipitation of mineral matter in the pore spaces. It is the last stage in the formation of a sedimentary rock.

Two Main Types of sedimentary Rock Clastic or Non-Clastic Clastic Sedimentary Rock-Made of small pieces

of other types of rocks (igneous, metamorphic, sedimentary). And are cemented together after deposition.

Non-clastic sedimentary rock: Non-clastic sedimentary rocks form from the precipitation (Precipitation is the separating of a solid from a solution) of minerals from ocean water or from the breakdown of the shells and bones of sea creatures.

Examples of Clastic Sedimentary Rock

Sandstone: a clastic sedimentary rock made up mainly of sand-size weathering debris

Conglomerate: a clastic sedimentary rock that contains large rounded clasts. generally filled with smaller particles and/or a chemical cement that binds the rock together. 

Shale: a fine-grained sedimentary rock that forms from the compaction of silt and clay-size mineral particles that we commonly call "mud". 

Examples of Non- ClasticLimestone is a sedimentary rock composed primarily of calcium carbonate (CaCO3) in the form of the mineral calcite. It most commonly forms in clear, warm, shallow marine waters. It is usually an organic sedimentary rock that forms from the accumulation of shell, coral, algal and fecal debris. It can also be a chemical sedimentary rock formed by the precipitation of calcium carbonate from lake or ocean water.Rock Salt is a chemical sedimentary rock that forms from the evaporation of ocean or saline lake waters. It is also known by the mineral name "halite". It is rarely found at Earth's surface, except in areas of very arid climate. It is often mined for use in the chemical industry or for use as a winter highway treatment. 

ESRT Scheme for Identifying Sedimentary Rocks

Last but Not Least,Metamorphic Rock Defined: form when any rock is changed by

the effects of heat, pressure, or chemical action.

Two types of Metamorphism Regional or Contact Metamorphic rocks are typically

characterized as: unfoliated or foliated.

Metamorphic Rock Metamorphic rocks form from either Igneous or Sedimentary

rocks that are effected by pressure and heat within the Earths surface.

Metamorphic Rock

New types of Metamorphic rock are formed depending on the amount of heat and pressure present around the rock.

Example: Sedimentary Rock – Shale

Regional Metamorphism

Contact Metamorphism

When molten rock come into contact with local rocks in a small area

Foliated Metamorphic Rocks Foliated Metamorphic Rock Definition: Metamorphic rocks whose

minerals are squeezed together under high pressure and arranged in wavy layers or bands

Examples:

Gneiss is foliated metamorphic rock that has a banded appearance and is made up of granular mineral grains. It typically contains abundant quartz or feldspar minerals. Schist is metamorphic rock with well

developed foliation. It often contains significant amounts of mica which allow the rock to split into thin pieces

Joke of the day….If it looks nice, it is probably Gneiss… If it looks like Schist, it is probably Schist…. Get it???

One more Example….Slate is a fine-grained, foliated metamorphic rock that is created by the alteration of shale or mudstone by low-grade regional metamorphism

Nonfoliated Metamorphic Rocks Definition: Metamorphic rock that lacks

mineral grains that are banded.

Examples

Marble is a non-foliated metamorphic rock that is produced from the metamorphism of limestone

Quartzite is a non-foliated metamorphic rock that is produced by the metamorphism of sandstone.