ns/lessons/metrocks/metrocks2.html
TRANSCRIPT
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