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ROCKS

“THE MIXTURE OF MINERALS”

Chapter 4

THE ROCK CYCLE

Rock – a naturally occurring solid mixture of

crystals of one or more minerals.

Rock Cycle – the continual process by which

new rock forms from old rock material.

Rocks are always changing.

WEATHERING, EROSION, AND DEPOSITION

Weathering – the process in which water, wind,

ice, and heat break down rock.

Weathering is very important:

Breaks down rock into fragments called sediment.

The fragments are the materials that are used to make

sedimentary rocks.

TYPES OF WEATHERING

Physical Weathering – Any process in which

rocks are broken down by contact with the

Earth’s atmosphere and water.

Chemical Weathering – Occurs when chemical

reactions break down the bonds holding the

rocks together.

Most common in areas that contain large amount

of water.

WEATHERING, EROSION, AND DEPOSITION

Erosion – the process by which sediment is

removed from its source.

Different types of erosion:

Wind

Ice

Water

Gravity

WEATHERING, EROSION, AND DEPOSITION

Deposition – the process in which sediment

moved by erosion is dropped and comes to

rest.

Once deposited, sediments may be compressed

and cemented to form a sedimentary rock.

HEAT AND PRESSURE

Heat and pressure may cause a rock to

chemical change into a metamorphic rock.

If the rock gets too hot it will melt which

eventually cools to form igneous rocks.

FOLIATION

Foliation – The set of layers visible in many

metamorphic rocks as a result of flattening and

stretching of mineral grains during

metamorphism.

BEDDING

Bedding – layers of sedimentary rock.

This can also be referred to as strata.

HEAT AND PRESSURE

The relationship of heat and pressure:

^Pressure ^ Heat

^ Heat ^ Pressure

MECHANICAL ENERGY

Gravitational Potential Energy – is the potential

energy associated with gravitational forces, as

work is required to elevate objects against

Earth’s gravity.

HOW THE CYCLE CONTINUES

Rock is exposed at the Earth’s surface by a

combination of uplift and erosion.

Uplift – is the movement within the Earth that

causes rocks inside the Earth to be moved to the

Earth’s surface.

After uplift, the rock reaches the surface, and the

cycle continues.

ROUND AND ROUND IT GOES

A TRIP AROUND THE ROCK CYCLE

1. You are going to need your notebook for this

activity.

2. In the output section record 10 rolls of the

dice. (Write down what the dice said.)

3. You may never move from a station but

continue to roll the dice at that station and

write down what the dice said.

4. Once you have finished return to your seat.

ROCK CLASSIFICATION

Three main classes of rock:

Igneous

Sedimentary

Metamorphic

In order to identify rocks scientist break the rocks up

into two categories:

Composition and Texture

COMPOSITION

Composition – the chemical makeup of a rock;

describes either the minerals or other materials

in the rock.

Determined by the minerals contained in the rock.

Ex. A rock made of mostly the mineral quartz will

have a composition very similar to that of quartz.

TEXTURE

Texture – is the quality of a rock that is based

on the sizes, shapes, and positions of the

rock’s grains.

There are three different grains of texture:

Fine-grained

Medium-grained

Coarse-grained

TEXTURE

The amount of time that a igneous rock is

allowed to cool determines the texture of the

rock.

If the rock cools quickly then it will be fine grained.

If the rock cools slowly then it would be coarse

grained.

The texture of a rock can reveal the processes that

formed it.

FINE GRAINED “SILKSTONE”

MEDIUM GRAINED “GRANITE”

COARSE GRAINED - CONGLOMERATE

INDIVIDUAL PRACTICE

ROGER THE ROCK

Your assignment: Create a children’s story, comic strip, or some other creative story about Roger the Rock.

Roger is a rock that has been a part of the rock cycle for millions of years. Your job is to tell Roger’s story. You must describe how Roger was “born” and at least three transitions that occurred during Roger’s life. (For example, changing from igneous to sedimentary, sedimentary to metamorphic, and metamorphic to igneous.)

Your grade will be based on in-class work, the accuracy of your information, creativity, and neatness/effort. This should be a story appropriate for a children’s story (think back to 2nd grade here!), including pictures.

To earn an “A”, you need to include many details-the names of specific rock types, descriptions about what causes the changes to occur, etc.

This project will be due on the day of Chapter 4 Test. These projects will be presented by you and your partner.

END OF SECTION 4.1

WARM UP

1. If all the continents were once joined as

Pangaea, what did the rest of Earth look like?

2. The following image is a picture of a

Cynognathus. Fossil remains can be found in

South America and Africa, this animal died

160 million years before the first boat was

used. What does this tell you about these land

masses?

ADD PHOTO OF EARTH’S LAYERS

Activity (Layers of the Earth)

ACTIVITY

At your table complete the foldable with your group.

There shouldn’t be any movement around the classroom. Use your classmates to help you complete the foldable.

Place your foldable in your notebook with tape.

Keep conversations within your group.

You will be given 20 minutes to complete the activity.

Information starts on page 233.

MECHANISMS THAT DRIVE LITHOSPHERIC

PLATES

Mantle Convection and Convection Currents

MECHANISMS THAT DRIVE LITHOSPHERIC

PLATES

Draw the diagram in your notebook.

Wegener’s Continental Drift Hypothesis

Continental drift – the hypothesis that states that the

continents once formed a single landmass, broke up,

and drifted to their present locations.

Alfred Wegener proposed the theory in the early

1900’s.

Group Activity

Round Robin – In this activity brainstorm with your

group what are some of the evidences that tectonic

plates move.

1 person will write down what your group discusses,

and 1 person will talk at a time.

Other group members will take turns sharing what

they think are possible signs of tectonic plates

moving.

If you become stuck utilize your book as a resource.

Wegener’s Continental Drift Hypothesis

Supporting Evidence

Plates Fit together like a puzzle.

Fossil Evidence across continents.

Rocks matched across seas.

Glacial striations on rocks matched on Africa and South

America proving a once super continent.

Coal on Antarctica proves that it was once warm.

Wegener’s Continental Drift Hypothesis

Wegener’s Continental Drift Hypothesis

Wegener’s Continental Drift Hypothesis

Inconclusive Evidence

No credible evidence that explained why the continents

moved.

The Drifting Continents

The Drifting Continents

The Drifting Continents

65 million years ago.

Dinosaurs became extinct and Laurasia and

Gondwana split into two smaller pieces.

Seafloor Spreading

Activity on seafloor spreading.

You will have 10 minutes to complete the drawing

of your model and 20 minutes to answer the

questions.

You may work with your table partners; but you

must complete your own as part of your notes.

Group Discussion

Mid-Ocean Ridges and Sea-Floor

Spreading

A chain of submerged mountains runs through the center

of the Atlantic Ocean.

Also known as Mid-ocean Ridges

Mid-ocean Ridges and Sea-Floor

Spreading (Draw the Diagram)

Evidence for Sea-Floor Spreading:

Magnetic reversals Draw Diagram

Warm up

You will have the first 10 minutes of class to finish

up the questions from 10/1/14’s activity on sea

floor spreading.

Quiz-Quiz Trade Review

You will be moving around the room for this activity.

In order to indicate that you need a partner you will raise your hand and find someone who also has their hand raised.

Ask your question, if your partner doesn’t know the answer give them a hint. If they are completely stuck give them the answer.

You will then be asked a question by your partner in the same process mentioned above.

After you have both answered each others questions trade your questions and raise your hand to find a new partner.

The Theory of Plate Tectonics

Plate Tectonics – the theory that explains how large

pieces of the Earth’s outermost layer called tectonic

plates, move and change shape.

Tectonic Plate Boundaries

Boundary – a place where tectonic plates touch.

There are three different types of boundaries:

Convergent

Divergent

Transform

Activity

Read the article provided about Convergent

Boundaries.

Discuss this article with your group and fill in the

guided notes.

Lastly paste this into your science notebook.

Convergent Boundaries

Convergent Boundary – the boundary formed by

the collision of two lithospheric plates.

There are three different types of convergent

boundaries:

Oceanic – Oceanic

Oceanic – Continental

Continental - Continental

Oceanic – Oceanic Plate Boundaries

http://geology.com/nsta/convergent-boundary-

oceanic-oceanic.gif

Oceanic – Oceanic Plate Boundary

Continental – Oceanic Plate

Boundaries “Mt. Adams”

http://geology.com/nsta/convergent-boundary-

oceanic-continental.gif

Eruption of Mt. Redoubt Alaska

Continental – Oceanic Plate

Boundaries

Continental – Continental Plate

Boundaries

http://geology.com/nsta/convergent-boundary.gif

Activity

Read the article provided about Divergent

Boundaries.

Discuss this article with your group and fill in the

guided notes.

Lastly paste this into your science notebook.

Divergent Plate Boundaries

Divergent Boundary – the boundary between two

tectonic plates that are moving away from each

other.

New Sea floor forms at divergent boundaries.

Mid-ocean ridges is the most common type of divergent

boundary.

Divergent Plate Boundaries

Activity

Read the article provided about Transform

Boundaries.

Discuss this article with your group and fill in the

guided notes.

Lastly paste this into your science notebook.

Warm-Up

Record the following vocabulary instructions and begin working on the assignment. (Due 10/09/14)

On a separate sheet of paper:

1. Rewrite the word and definition into your science notebook in your own words

2. Draw a picture or diagram to represent your vocabulary word.

3. Write a sentence that properly uses the word and describes the word. Example: Volcanoes are large mountains that form from repeated eruptions that allow them to continue to grow every time they erupt.

Transform Boundaries

Transform Boundary – The Boundary between

tectonic plates that are sliding past each other.

Ex. San Andreas Fault in California.

One of the few faults that can be visibly seen.

One of the major causes of Earthquakes.

Transform Plate Boundaries

Plate Summary

Tracking Tectonic Plate Motion

Tectonic plates move roughly 5cm per year.

The rate is so slow that it cannot be seen nor felt except

during an Earthquake.

Plate movement is tracked by GPS.

Fall Zone

The fall zone marks the geologic boundary of hard metamorphosed terrain and the sandy, relatively flat outwash plain of the upper continental shelf.

◦ The transition from the harder metamorphosed rock to the softer sediment creates water falls.

Formed from the erosion of the mountain regions of NC to help form the Sandy coastal plain regions.

Review/Quiz

Turn to Page 275 and answer questions 1-

10.

You must write the letter and the answer.

Activity

Plate Tectonic posters.

YOU HAVE 15 MINUTES TO

COMPLETE THIS ASSIGNMENT.

Volcanic Eruptions

Volcanoes – are areas of Earth’s surface through which magma and volcanic gases pass.

Explosion of a volcanic eruption can turn an entire mountain into a billowing cloud of ash and rock in a matter of seconds causing global climate temperatures to drop.

Help form fertile land.

Create some of the largest mountains on earth.

Volcanic Eruptions

Magma – melted rock below the Earth’s surface.

Lava – Melted rock above the Earth’s surface.

Mt. Cleveland- Aleutian Islands, Alaska

Stromboli Volcano - Sicily

Mount Redoubt - Alaska

Types of Lava Flows

Pahoehoe lava flows – sheet like lava flows that result in continuous surfaces.

Flow smoothly

Move forwards in tongues or lobes and are characterized by a glassy, plastic skin.

Pahoehoe Lava Flow

Types of Lava Flows

Aa – lava pours out quickly and forms a brittle crust.

The crust is torn into jagged pieces as molten lava continues to flow underneath.

Got its name because of the painful experience of walking barefoot across the jagged surfaces.

Associated with lava fountaining.

Aa Lava Flow

Lava Fountaining

Lava Fountaining – spraying of lava into the air pulsing with the pressure of escaping gases.

Types of Lava Flows

Pillow lava – forms when lava erupts underwater.

Lava forms rounded lumps that are the shape of pillows.

What erupts from a Volcano?

Lava – liquid magma that flows from a volcanic vent.

Pyroclastic material - forms when magma is blasted into the air and hardens.

Volcanic Bombs

Volcanic Bombs – large blobs of magma that harden in the air.

The shape of the bomb was caused by the magma spinning through the air as it cooled.

Lapilli

Lapilli – pebblelike bits of magma that hardened before they hit the ground.

Means “little stones”

Volcanic Ash

Volcanic Ash – forms when the gases in stiff magma expand rapidly and the walls of the gas bubbles explode into tiny, glasslike slivers.

Makes up most of the pyroclastic material in an eruption.

Volcanic Ash

Pyroclastic Flows

Pyroclastic Flow – produced when enormous amounts of hot ash, dust, and gases are ejected from a volcano.

Can move downhill at 200km/h.

Center of the flow can exceed 700 C.

Effects

End of Section 9.1

Types of Volcanoes:

Type of Volcanoe How does it form?

Describe what it looks like.

Draw a picture of the Volcano.

Cinder Cone

Stratovolcano (Composite)

Shield Volcano

What is the difference between a crater and a caldera?

Mauna Kea - Shield Volcano

Cinder Cone Volcanoes

Mt. St. Helens

Mt. St Helens

Mt. Fuji

Craters

Crater – funnel-shaped pit found around the central vent at the top of many volcanoes.

When eruption stops, lava drains back underground making a larger collapsed crater.

Next eruption may blast it away creating a larger and deeper crater.

Kamchatka, Russia

Calderas

Caldera – a large, semicircular depression that forms when the magma chamber below a volcano partially empties and causes the ground above to sink.

Much larger than a crater.

Crater Lake, Washington

Lava Plateaus

Lava Plateau – a wide, flat landform that results from repeated nonexplosive eruptions of lava that spread over a larger area.

Formed from seepage of magma from long cracks or rifts.

Lava can pour out for millions of years and spread over huge areas.

Lahar (mud) Flows

A type of mudflow or debris flow composed of a slurry of pyroclastic material, rocky debris, and water.

Typically occurs along a river.

Has the density and consistency of concrete.

Possible Causes of a Lahar

Melted glaciers

Mixture with wet soil to create a viscous material.

Water from a crater lake.

Columbia River Plateau

Activity

Earthquake and Volcano Patterns

Where Volcanoes Form

Most volcanoes are found directly on tectonic plate boundaries.

80% of active volcanoes on land form where plates collide.

15% form where plates separate.

Other rare and few volcanoes form far away from plate boundaries known as hotspots.

Ring of Fire

The location of the worlds most active volcanoes.

The ring is entirely located along plate boundaries in which many earthquakes occur as well.

Hotspots

Hotspot – is a location on the Earth’s surface that has experienced active volcanism for a long period of time.

Often located in the middle of oceanic plates.

Hawaii is an example of an active hotspot.

End of Volcanoes

Warm Up – 5 Minutes

1. When two tectonic plates collide they form a ________ boundary.

2. Which convergent crustal interaction forms a mountain?

3. Describe how the great rift valley in Africa was formed.

4. Draw a picture illustrating how a hot spot forms island chains.

EarthquakesActivity: Complete the first diagram with your group

partners.

What Are Earthquakes?

Seismology – the study of earthquakes.

Seismologist – scientist who study

Earthquakes.

Earthquake – the shaking of the Earth’s

surface due to the movement of tectonic

plates.

Where Do Earthquakes Occur?

Most if not close to all Earthquakes occur

near the edges of tectonic plates.

◦ Due to the movement of tectonic plates,

numerous features called faults exist in the

Earth’s crust.

Fault – is a break in the Earth’s crust

along which blocks of the crust slide

relative to one another.

Where Do Earthquakes Occur?

What Causes Earthquakes?

Deformation – the bending, tilting, and

breaking of the Earth’s crust; the change

in the shape of rock in response to stress.

This process occurs in two ways:

◦ Plastic deformation.

◦ Elastic deformation.

Plastic Deformation

Plastic Deformation

– a rock that

deforms in a

stretching gentle

manner.

◦ Example: Pulling apart

a piece of molded clay.

Elastic Deformation

Elastic Deformation –

rock is stretched until

it can no longer stand

the force in which the

rock springs back to

its original location.

◦ Rock can stretch farther

than steel without

breaking.

Example: Stretched

rubber band.

Elastic Rebound

Elastic Rebound – the sudden return of

elastically deformed rock to its

undeformed shape.

◦ Occurs when more stress is applied to the

rock than the rock can stand.

Energy is released during the rebound.

◦ Energy is released as seismic waves.

Visualizing Elastic Rebound

http://projects.crustal.ucsb.edu/understan

ding/elastic/rebound.html

1906 Earthquake

EARTHQUAKE!

Activity

With your group partners fill in the

diagram describing the different types of

waves.

How Do Earthquake Waves Travel?

Seismic Wave – a wave of energy that

travels through the Earth, away from an

earthquake in all directions.

Body Waves – seismic waves that travel

through the Earth’s interior.

Surface waves – seismic waves that travel

along the Earth’s surface.

Types of Waves

P-waves or Primary Waves – Types of

seismic waves that move in a compression

manner.

◦ Ex. A slinky moving back and forth from end

to end.

◦ Has the ability to move through all materials.

◦ Fastest moving wave.

Types of Waves

P-waves are always the first waves of an

earthquake to be detected.

Types of Waves

S-Waves or Secondary waves – are waves

that move up and down.

◦ Ex. Stretching a slinky outward and then

pulling down on the center so that it would

bounce up and down.

◦ Cannot move through a liquid.

◦ Waves are very damaging to surface objects.

Types of Waves

S-waves are also known as shear waves

because of the damage they cause to the

Earth’s rocks at the surface.

S-waves cannot travel through parts of

the Earth that are completely liquid.

S-waves are slower than P-waves and

always arrive later than P-waves.

S&P Waves

Surface Waves

Surface Waves – are waves that move along the Earth’s surface and produce motion mostly in the upper few kilometers of Earth’s crust.

Two types:

1. Rayleigh Wave - Produces up, down, and around motion.

2. Love Waves - Back and forth motion much like S-waves.

These waves are more destructive than body waves and move more slowly

Surface Waves

Locating Earthquakes

Seismographs – instruments located at or

near the surface of the Earth that record

seismic waves.

Seismogram – tracing of earthquake

motion recorded by a seismograph.

Determining Time and Location of

Earthquakes Epicenter – the point on the Earth’s

surface directly above an earthquake’s

starting point

Focus – the point inside the Earth where

an earthquake begins.

Activity

S-P Time Method Lab

“Locating the Epicenter”

The S-P Time Method

S-P time method – the way in which

seismologists find an earthquake’s

epicenter.

◦ Collect several seismograms of the same

earthquake from different locations.

◦ Seismograms are placed on a time-distance

graph.

◦ By reading the horizontal axis the distance

from the earthquake can be determined.

The S-P Time Method

The Richter Magnitude Scale

Richter scale – a scale used to measure

the strength of an earthquake.

Earthquake Ground Motion

Magnitude – the strength of an

earthquake.

Every time that the Richter scale

increases by one it will produce 10x as

much ground motion.

◦ Ex. 5 on the scale will be 10x stronger than an

earthquake that is a 4.

Modified Mercalli Intensity Scale

Intensity – a measure of how much

damage caused by the earthquake.

◦ The Scale uses roman numerals I-XII

◦ Shows the type of damage caused by an

earthquake.

Strength and Frequency

Earthquakes vary in strength.

Earthquakes don’t occur on a set

schedule.

◦ But, the strength of an earthquake is related

to how often they occur.

Strength and Frequency

The Gap Hypothesis

Gap hypothesis – a hypothesis that states

that sections of active faults that have had

relatively few earthquakes are likely to be

the sites of strong earthquakes in the

future.

Seismic Gap – areas along a fault where

relatively few earthquakes have occurred.

What causes change in sea-level?