BIG IDEA 6: Earth Structures

Description

Over geologic time, internal and external sources of energy have continuously altered the features of Earth by means of both constructive and destructive forces. All life, including human civilization, is dependent

on Earth's internal and external energy and material resources.

Benchmark Number & Descriptor• S C . 7 . E . 6 . 1• D e s c r i b e t h e l aye rs o f t h e s o l i d Ea r t h , i n c l u d i n g t h e l i t h o s p h e re , t h e h o t c o nve c ti n g m a nt l e ,

a n d t h e d e n s e m eta l l i c l i q u i d a n d s o l i d c o re s .• S C . 7 . E . 6 . 2• I d e nti f y t h e p att e r n s w i t h i n t h e ro c k c yc l e a n d re l ate t h e m to s u r fa c e eve nt s ( we at h e r i n g

a n d e ro s i o n ) a n d s u b - s u r fa c e eve nt s ( p l ate te c to n i c s a n d m o u nta i n b u i l d i n g ) .• S C . 7 . E . 6 . 3• I d e nti f y c u r re nt m et h o d s fo r m e a s u r i n g t h e a ge o f Ea r t h a n d i t s p a r t s , i n c l u d i n g t h e l aw o f

s u p e r p o s i ti o n a n d ra d i o a c ti ve d ati n g .• S C . 7 . E . 6 . 4• E x p l a i n a n d g i v e exa m p l e s o f h o w p hys i ca l ev i d e n c e s u p p o r t s s c i e nti fi c t h e o r i e s t h at Ea r t h

h a s evo l v e d o ve r ge o l o g i c ti m e d u e to n at u ra l p ro c e s s e s .• S C . 7 . E . 6 . 5• E x p l o re t h e s c i e nti fi c t h e o r y o f p l ate te c to n i c s b y d e s c r i b i n g h o w t h e m o ve m e nt o f Ea r t h ' s

c r u sta l p l ate s ca u s e s b o t h s l o w a n d ra p i d c h a n ge s i n Ea r t h ' s s u r fa c e , i n c l u d i n g v o l ca n i c e r u p ti o n s , e a r t h q u a ke s , a n d m o u nta i n b u i l d i n g .

• S C . 7 . E . 6 . 6• I d e nti f y t h e i m p a c t t h at h u m a n s h ave h a d o n Ea r t h , s u c h a s d efo re stati o n , u r b a n i zati o n ,

d e s e r ti fi cati o n , e ro s i o n , a i r a n d wate r q u a l i t y, a n d c h a n g i n g t h e fl o w o f wate r.• S C . 7 . E . 6 . 7• Re c o g n i ze t h at h e at fl o w a n d m o ve m e nt o f m ate r i a l w i t h i n Ea r t h ca u s e s e a r t h q u a ke s a n d

vo l ca n i c e r u p ti o n s , a n d c re ate s m o u nta i n s a n d o c e a n b a s i n s .

INSIDE THE EARTH

EARTH’S LAYERS

• The Earth is divided into FOUR main layers: – Crust– Mantle– Outer Core– Inner Core

EARTH’S CRUST• Outer layer of Earth’s

surface• Makes up 1% of Earth• 2 types of crust:

– Oceanic– Conti nental

• Earth’s crust is broken down into pieces known as tectonic plates.

Mantle• Earth’s largest layers• Made mostly of

silicon, oxygen, magnesium and iron

• Pieces of mantle can be obtained by erupting volcanoes.

OUTER CORE• Is about 3000 miles

beneath the Earth’s crust

• Said to be made up of molten lava– Iron– Nickel

• This lava fl ows very slowly inside the Earth, creati ng a magneti c fi eld.

INNER CORE• Deepest part of

Earth• Smallest section

inside Earth• Solid mass due to

intense pressure– composed of iron

and nickel

BOUNDARIES between LAYERS• Moho Discontinuity

• Located between the crust and mantle

• Plastic Like Layer• Part of the upper mantle

• Shadow Zone• Part of the liquid outer

core

KNOWLEDGE CHECK

1. How many layers make up Earth?2. Which layer of Earth contains tectonic

plates?3. Which is Earth’s largest layer?4. Which elements in Earth’s core helps

create a magnetic field?

KNOWLEDGE CHECK

1. How many layers make up Earth? 42. Which layer of Earth contains tectonic

plates? Earth’s crust3. Which is Earth’s largest layer? Mantel4. Which elements in Earth’s core helps

create a magnetic field? Nickel and Iron

IT’S JUST A LITTLE ROCK.

Earth’s Past and Future

• Earth has been transforming for the past 4.5 million years.

• The energy for this constant transformati on comes from the Earth's molten interior.

• Earth will probably conti nue to evolve for another 4-5 billion years into the future.

• This energy from Earth’s interior has driven the Earth's physical/chemical evoluti on, and been ulti mately responsible for all the rocks, conti nents, mountains, foreland basins, etc.

The Rock Cycle• Rocks are naturally

occurring. • Rocks contain minerals,

organic material, and glass.

• There are 3 types of rocks:– Igneous– Metamorphic– Sedimentary

• Each type of rock can become a new type by traveling through the rock cycle. http://www.volcanoworld.org/vwdocs/vwlesso

ns/lessons/Metrocks/Metrocks2.html

IGNEOUS ROCKS

• Origins: – Come from volcanoes– When

magma(inside)/Lava (outside) cool

• Types of Lava/Magma:– Due to locati on of

Volcano• Basalti c – Hawaii, non-

explosive volcanoes• Andesiti c – Pacifi c ocean

volcanoes• Graniti c – very explosive

volcanoes

• Categories of Igneous Rocks:– Intrusive

• Formed inside Earth• Found when volcano

erupts and are pushed out or through mining

• Contain large mineral grains

– Extrusive• Form outside surface• Lava cools quickly• Rocks general ly contain

holes; gas escapes

EXAMPLES OF IGNEOUS ROCKS

Pumice is lava that had a lot of gases in it and cooled quickly on the surface of the Earth.

Granite: Igneous, Intrusive

Obsidian - volcanic glass that is formed by very rapid cooling of lava

METAMORPHIC ROCKS• Origin:

– Rocks that form from change in temperature and pressure

• Earth Processes:– Heat and Pressure

• Rocks are beneath the surface; heat and pressure increases.

• Rocks do not melt, but they do exchange minerals creati ng new rocks.

– Fluids• Fluids carrying dissolved

minerals react with rocks.• Chemical reacti on occurs,

and new rocks are formed.

• Earth’s Relati on– They can form from

tectonic processes such as conti nental coll isions.

– They are also formed when rock is heated up by the intrusion of hot magma from the Earth's interior.

– Metamorphic rocks become exposed at the Earth's surface by erosion and uplift .

– Studying metamorphic rocks tells us about the temperatures and pressures that occur at great depths within the Earth's crust.

EXAMPLES OF METAMORPHIC ROCK

– Foliated• Mineral grains are

fl att ened into layer.• Example - GNEISS: A

foliated rock usually made from some type of granite

– Non-Foliated• Smooth texture, no

layers• Example - Quartzite

SEDIMENTARY ROCKS• Rocks created from

sediments.• Materials that make up

sediments: – Weathered and eroded rock– Plant and animal remains– Minerals that fal l out of

soluti on• Relati onship to Earth

– Sediments are formed by both weathering and erosion.

– Sediments are then transported to their place of depositi on by water, wind, mass movement, or glaciers.

• Ways sedimentary rocks form:– Compacti on

• Sediments are pressed together.

– Cementati on• Sediments are glued

together.– Depositi on of minerals

• Minerals in soluti on are left when water evaporates.

EXAMPLES OF SEDIMENTARY ROCKS

• DETRITAL: – Made of broken fragments of other rocks

• CHEMICAL:– Made of minerals dissolved in soluti on

• BIOCHEMICAL: – Made of the remains of once-living things

Fossillferous Limestone contains fossils of various fresh and or salt water shell fish.

Breccia composed of sharp angled fragments

Rock Salt: This is an evaporate after the water evaporated from saltwater.

KNOWLEDGE CHECK

1. Where is the beginning of the rock cycle?

2. NAME THAT ROCK: 1. This rock is formed from organic,

inorganic, and rock fragments.2. This rock is formed from heat and

pressure.3. This rock is formed from molten

lava/magma.

KNOWLEDGE CHECK

1. Where is the beginning of the rock cycle? It is a cycle; therefore, there is no true beginning or end.

2. NAME THAT ROCK: 1. This rock is formed from organic, inorganic,

and rock fragments. Sedimentary2. This rock is formed from heat and pressure.

Metamorphic3. This rock is formed from molten lava/magma.

Igneous

HOW OLD IS THIS BIG ROCK?

HOW OLD IS EARTH?

• Rocks are an open window to Earth’s past.• James Hutt on (18th century) believed Earth

had to be much older then what was originally thought – probably millions of years old.

• He proposed his principle of Uniformitarianism.

• Big Idea: – Geological processes that we see occurring today

are the same processes that occurred in the past.

DATING EARTHLAW of SUPERPOSITION

• Superpositi on refers to, “placing on top of each other.”

• Scienti sts use the Law of Superpositi on to determine whether a fossil or a layer of rock is older or younger than another fossil or layer of rock.

• This law states that in a series of sedimentary rock layers, younger rocks normally l ie on top of older rocks.

DATING EARTHRADIOACTIVE DATING

• Scienti st use the decay of radioacti ve elements to determine the age of rocks.

• Radiometric dati ng indicates that the Earth is about 4.570 billion years old

• Radioacti ve Decay: – Unstable elements that

breakdown, or decay, by releasing parti cles and energy in the process and form another element

• Carbon – 14– Used to fi nd the

absolute age of rocks– Carbon-14 has a half-life

of 5730 years.– It is only useful for

dati ng materials that contain Carbon and lived no more than 50,000 years ago.

KNOWLEDGE CHECK

1. Describe the principle of Uniformitarianism.

2. When looking at a cross-section of the Grand Canyon, layers are noticed. What law best describes these layers?

3. What element must be present in order to use radioactive dating?

KNOWLEDGE CHECK

1. Describe the principle of Uniformitarianism. Geological processes that we see occurring today, are the same processes that occurred in the past.

2. When looking at a cross-section of the Grand Canyon, layers are noticed. What law best describes these layers? Law of Superposition

3. What element must be present in order to use radioactive dating? Carbon-14

WHY DOES EARTH LOOK THE WAY IT DOES?

HOW DID THAT GET HERE?• The Earth is said to be

4.57 billion years old.

• In order for Earth to look the way it does today many factors are taken into considerati on.

• Physical geology is the study of the Earth's rocks, minerals, and soils and how they have formed through ti me.

• Complex internal processes such as plate tectonics and mountain-bui lding have formed these rocks and brought them to the Earth's surface.

• Earthquakes are the result of the sudden movement of crustal plates, releasing internal energy that becomes destructi ve at the surface.

• Internal heat and energy are released also through volcanic erupti ons.

• External processes such as g lac iati on, running water, weathering , and erosion have formed the landscapes we see today.

http://www.cliffsnotes.com/study_guide/History-of-Physical-Geology.topicArticleId-9605,articleId-9456.html

EVIDENCE of EARTH’S EVOLUTION

TYPES of EVIDENCE1. Evidence located at

PLATE BOUNDARIES

2. Evidence left behind from WEATHERING

3. Evidence left behind from EROSION AND DEPOSITION

EXAMPLES of EVIDENCE1. Himalayas, Andes, Hawaiian

Islands – all found at diff erent plate boundaries.

2. Stalacti tes and stalagmites are the remains of rocks which went through chemical weathering.

3. Gullys, deltas, valleys, sand dunes, landslides are created through ti me as a result of moving water, ice, wind, and gravity.

EVIDENCE of EARTH’S EVOLUTION

TYPES of EVIDENCE1. Evidence from

LANDFORMS - PANGEA

2. Evidence of FOSSILS

3. Evidence from CLIMATE

EXAMPLES of EVIDENCE1. Mountain ranges in

Africa line up with those in South America.

2. Fossils of the plant Glossopteris found in rocks on widely separated landmasses

3. Fossils of tropical plants found near Arcti c Circle

KNOWLEDGE CHECK

1. Approximately how old is planet Earth?

2. List and explain 4 pieces of evidence supporting Earth’s evolution.

KNOWLEDGE CHECK

1. Approximately how old is planet Earth? The Earth is said to be 4.57 billion years old.

2. List and explain 4 pieces of evidence supporting Earth’s evolution.

1. Pangaea – Super conti nent2. Fossils – Similar fossils found in diff erent areas3. Erosion and Depositi on – formati on of gullies,

deltas, valleys, etc.

WE’RE FLOATING ON PLATES?

PLATE TECTONICS• The Earth’s crust and upper mantle are broken into

secti ons called plates.

• Plates move around on top of the mantle like raft s in a pool.

• Earth’s plates are located on the lithosphere (crust and upper mantle).

• The average thickness of a plate is 100 km (62 miles).

• Most plates support both conti nent and ocean.

Alfred Wegener

•Proposed a theory stating that in the distant past, the Earth’s continents were all joined as a single landmass.

• When Wegener placed all the continents together like a puzzle, it formed a large landmass which he called Pangaea.

•Wegener stated that this supercontinent began to break up about 200 million years ago.

PLATE BOUNDARIES• Earth’s crust is made up

of 7 major plates and several smaller ones.

• Where the edges of these plates meet is known as a PLATE BOUNDARY.

• How the plates are moving determines what type of boundary is between them.

TYPES of BOUNDARIES

• Plates collide into each other.• These collisions produce mountains,

earthquakes, and volcanoes. – Example: • Andes Mountains• Aleuti ans Islands

CONVERGENT BOUNDARY

3 TYPES of CONVERGENT BOUNDARIES

1. Ocean plate colliding with a less dense conti nental plate• Subducti on Zone: where the less dense plate sl ides under the

more dense plate• VOLCANOES occur at subducti on zones.• Example: Andes Mountains

2. Ocean plate colliding with another ocean plate• The less dense plate sl ides under the more dense plate creati ng

a subducti on zone cal led a TRENCH• Example: Aleuti an Islands

3. A conti nental plate colliding with another conti nental plate• a place where folded and thrust faulted mountains form• Example: Himalayas

CONVERGENT BOUNDARIES

TYPE 1 TYPE 2

TYPE 3

TYPES of BOUNDARIES

• Plates move away from each other.• Most of these boundaries are found in

the oceans.• At divergent boundaries, mid-ocean

ridges and rift s are formed.

DIVERGENT BOUNDARY

DIVERGENT BOUNDARY• The best known of the

divergent boundaries is the Mid-Atlanti c Ridge.

• This submerged mountain range extends from the Arcti c Ocean to beyond the southern ti p of Africa.

• The rate of spreading along the Mid-Atlanti c Ridge averages about 2.5 centi meters per year (cm/yr) or 25 km in a million years.

TYPES of BOUNDARIES

• Plates slide past each other. • The sliding of these plates causes rocks

to rub against each other. At times, these rocks break and inch past each other. These breaks are felt as earthquakes.

TRANSFORM BOUNDARY

TRANSFORM BOUNDARY

• The San Andreas Fault is a result of the Pacific and North American plates sliding past each other.

• These plates are moving at about 5cm a year.

KNOWLEDGE CHECK

1. Explain the theory of plate tectonics.2. How many plate boundaries are there?3. Name the type of plate boundary each

feature is located at: A. Andes MountainsB. Mid-Ocean RidgeC. San-Andrea’s Fault

KNOWLEDGE CHECK

1. Explain the theory of plate tectonics. Earth’s crust is broken up into plates which fl oat on top of the mantle. The plates support the conti nents and oceans.

2. How many plate boundaries are there? 3 types of plate boundaries

3. Name the type of plate boundary each feature is located at:

A. Andes Mountains - Convergent B. Mid-Ocean Ridge - DivergentC. San-Andrea’s Fault - Transform

MOUNTAINS, VOLCANOES, EARTHQUAKES –

HOW THEY FIT IN THE PICTURE

Convection Currents• Hot magma in the Earth

moves toward the surface, cools, then sinks again.

• This movement creates convecti on currents beneath the plates that cause the plates to move.

• When the plates move, mountains, earthquakes, and volcanoes form.

MOUNTAINS

• Mountains are formed when uplift occurs (Forces within the crust lift the land above).

• 3 types of mountains can form due to plate movement: – Folded mountains– Fault-Block mountains– Volcanic mountains

• Yes, volcanoes are considered mountains.

MOUNTAIN FORMATION

FOLDED Mountains• Folded mountains are formed

by crust which have been uplift ed and folded by compressional forces.

• These mountains occur along convergent plate boundaries either between conti nental plates or between an oceanic and a conti nental plate.

• Examples: – Rockies– Andes– Alps– Himalayas

FAULT-BLOCK Mountains• These mountains form

when faults or cracks in the Earth's crust force some materials or blocks of rock up and others down.

• Instead of the Earth folding over, the blocks are stacked.

• Examples:– Sierra Nevada Mts. – Harz Mts.

VOLCANOES

INFORMATION• Volcanoes form when material

from inside the Earth reaches the surface.– Magma: Molten rock found

inside the Earth– Lava: Molten rock when

outside surface is reached

• Volcanoes are most commonly found at both convergent and divergent plate boundaries.

• A major belt of volcanoes is the “Ring of Fire” which encircles the Pacifi c Ocean.

WHY THEY EXPLODE• Temperatures in the mantle

are hot enough to melt rock into magma .

• Since magma is less dense than the solid rock around it, magma rises and some of it collects in magma chambers.

• As the magma rises, pressure decreases allowing trapped gasses to expand and propel the magma through openings in the Earth’s surface causing an erupti on.

3 TYPES OF VOLCANOES

• SHEILD VOLCANOES– Broad shaped, quiet erupti ons– Examples: Kilauea, Hawaii and Mt. Etna, Italy

• CINDER CONE VOLCANOES– Steep sided, explosive erupti ons (usually throws

lava and rock high into the air)– Example: Paricuti n, Mexico

• COMPOSITE VOLCANOES– Steep sided, erupti ons vary from quiet to explosive– Example: Mt. St. Helens

TYPES OF VOLCANOES

Mt. Etna, ItalyShield Volcano

1943 Eruption of Paricutin – MexicoCinder cone Volcano

Mt. St. Helens, 1982Composite Volcano

ENVIRONMENTAL EFFECTS

• Earth’s surface is greatly affected by volcanoes.

LAND AIR WATER

Lava Poisonous gasses Hot Springs

Volcanic Ash Acid Rain Geysers

Landslides Haze Deep Sea Vents

Mudflows Lower Temps Fumaroles

EARTHQUAKES

• Earth’s crust movement causes stress among rocks under its surface.

• Stress can cause rocks to bend and stretch.

• Eventually rocks will break away from one another.– Area in which the rocks break and

move is called a fault.• When rocks break, vibrations are

produced called an earthquake.

Elastic Rebound Theory

• Explains how energy is stored in rocks– Rocks bend until

the strength of the rock is exceeded.

– Breaks occurs and the rocks quickly rebound to an undeformed shape.

– Energy is released in waves that radiate outward from the fault.• Fault: surface

that rocks/plates move along

ROCKIN ‘N’ ROLLINFOCUS

• Locati on where the earthquake energy is released inside the Earth.

• At the focus, seismic waves are produced and sent out.– What we feel

SEISMIC WAVES1. Primary Waves (P Waves)

– Travel through rocks– Take a st ra ight path– Move the fastest

2. Secondary Waves (S Waves)– Causes rocks to v ibrate– Takes a st ra ight path– Rocks m ove up/down

3. Surface Waves– Move above ground– Move up/down and s ide/s ide– Causes destructi on– Travels the s lowest

WHAT’S the DAMAGESEISMIC WAVES• The damage from

earthquake waves depends on several factors. – Intensity and duration

of the vibrations – The nature of the

material on which the structure is built

– The design of the structure

OTHER DANGERS• Tsunami

– The ocean f loor moves vertically along a fault .

– The vibration of a quake sets an underwater landslide into motion.

• Landslides– The greatest damage

to structures is from landslides and ground subsidence.

– The sinking of the ground can also be tr iggered by vibrations.

KNOWLEDGE CHECK

1. What causes plates to move on the mantle’s surface?

2. What force causes mountains to form? 3. What type of boundaries are most common

to find volcanoes? 4. List 3 ways volcanoes change Earth. 5. Where land moves and breaks is known as? 6. Which type of Seismic Waves causes the

most damage?

KNOWLEDGE CHECK

1. What causes plates to move on the mantle’s surface? Convecti on currents

2. What force causes mountains to form? Uplift 3. What type of boundaries are most common to

fi nd volcanoes? Convergent and Divergent4. List 3 ways volcanoes change Earth. Air polluti on,

acid rain, geysers5. Where land moves and breaks is known as? Faults6. Which type of Seismic Waves causes the most

damage? Surface Waves

It’s Not Just NatureChanging our EARTH

ENVIRONMENTAL POLLUTION

POLLUTION• Polluti on is the harmful

alterati on of our environment by our own acti ons.

• People depend on biological diversity for the quality of their lives.

TYPES of POLLUTION• Air Polluti on

– Caused by the burning of fossil fuels

• Water Polluti on– Sewage, chemicals, etc.

• Land Polluti on– Pesti cides, herbicides,

garbage

• Global Warming– Ozone depleti on

Threat to the Ecological Balance

VEGETATION• Vegetati on is a source of food,

building material, fuel, and medicine.

• Destructi on of vegetati on: – Fire

• clearance of vegetati on, soil erosion, fl ooding, and wind erosion

– Deforestati on• Ecosystems, nutrient

cycles are aff ected as well as a loss of biodiversity

SOIL• Soil is unique in that it depends

on plants and vegetati on for its existence, yet plants depend on soil for their support, air, water, and nutrients.

• Destructi on of soil: – Soil compacti on

• Prevents plant growth and encourages erosion

– Erosion of soil• Increases fl ooding,

landslides, and increases sediment loads leading to si lti ng up of reservoirs

Threat to the Ecological Balance

OCEANS• The ocean has the greatest

biodiversity anywhere on the planet.

• Destructi on of oceans and its contents:– Over fi shing

• The depleti on of fi sh in one area can cause the destructi on of marine ecosystems.

– Water polluti on• Caused by untreated sewage,

oi l , industr ia l chemicals , and radioacti ve waste

LANDSCAPE• Over the past century,

humans have radically altered the face of the Earth.

• Destructi on of land:– Mining

• Pull ing out natural resources

• Dumping of waste– Building

• Causes loss of habitat by harvesti ng natural resources - Urbanizati on

Threat to the Ecological Balance

AIR• Sources of air polluti on

are volcanoes, factories, and cars (both human and natural acti viti es).

• Destructi on of Air Quality:– Greenhouse Eff ect

• When fossi ls fuels are burned, excess carbon dioxide is created resulti ng in the depleti on of the ozone layer – Global Warming

WATER QUALITY• Surface and groundwater

contaminati on come greatly from factories, homes and farms.

• Destructi on of Water Quality:– Water Contaminati on

• Ferti l izers , insecti cides, and fl uids f rom cars run off into ponds, r ivers , and streams contaminati ng them.

• Some of th is pol luted water seeps into the ground contaminati ng our dr inking water.

KNOWLEDGE CHECK

1. Why is it important to keep a balance between humans and their ecosystem?

2. Identify the action with the location: 1. Deforestation A. Water Quality2. Ferti lizers B. Oceans3. Urbanization C. Landscape4. Acid Rain D. Air5. Increased Carbon Dioxide E. Vegetation

KNOWLEDGE CHECK

1. Why is it important to keep a balance between humans and their ecosystem? People depend on biological diversity for the quality of their lives.

2. Identify the action with the location: 1. Deforestati on E A. Water Quality2. Ferti lizers A B. Oceans3. Urbanizati on C C. Landscape4. Acid Rain B D. Air5. Increased Carbon Dioxide D E. Vegetati on