AICE Environmental Management UNIT 1 Lithosphere GUIDED READING

AICE Environmental Management UNIT 1: Lithosphere

GUIDED READING QUESTIONS 1. Define lithosphere. 2. Describe the internal structure of the earth, including the characteristics of the core, mantle, asthenosphere. 3. Differentiate between oceanic and continental crust. 4. Describe how seismic wave data provides evidence of earth structure. (a sketch might be useful) 5. Name the 7 major (primary) plates and the minor plate with the coolest name. 6. For each of the following plate boundaries, describe the characteristics of the boundary and the natural hazards/ geologic processes that tend to be associated with that boundary: a. Destructive (Convergent) b. Constructive (Divergent) c. Conservative (Transverse) 7. How do convection currents relate to the plate movements? 8. Explain sea-floor spreading. 9. Discuss the following types of evidence that exists to support the plate tectonic theory (post-Pangaea plate movement): a. Paleo-magnetism b. Paleontology c. Geographic fit

L. KQ. 1. : What are the key elements of the structure of the Earth? � characteristics of the core, mantle, asthenosphere � difference between oceanic & continental crust � convection currents � seismic waves data as evidence � plate tectonics & major plates � types of plate boundaries � seafloor spreading � post-Pangaea plate movement evidence

BELLRINGER If you journeyed to th e center of the Earth, wh at do you think you wou ld see along the way?

Earth’s Structure – The Layers Chemical Composition �divided into three layers ◦ crust ◦ mantle ◦ core (inner & outer) GR #2

Earth’s Layers: The Crust �outermost layer of the Earth � 5 to 100 km thick (thinnest layer) �made up of oxygen, silicon and aluminum (light minerals) �least dense

GR #3 Continental vs. Oceanic Crust Continental Crust located beneath land masses & under shallow seas Oceanic Crust located beneath deep ocean very thick – b/w 30 – 60 km very thin – b/w 5 – 8 km less dense (e. g. granite) denser (e. g. basalt)

Earth’s Layers: The Mantle �layer of the Earth b/w the crust & the core �much thicker than the crust (2, 900 km) � 67% of the mass �more magnesium, less aluminum & silicon than crust �more dense than crust

Earth’s Layers: The Core �the central part of the Earth that lies below the mantle �makes up 33% of Earth’s mass �radius 3, 430 km �made mostly of iron and smaller amounts of nickel (heavy minerals) �most dense layer

Earth’s Physical Structure

Earth’s Physical Structure – The Lithosphere �outermost, GR #1 rigid layer of the Earth �derived from the greek word “lithos” meaning rocky stone �divided into pieces called tectonic plates �made up of two parts ◦ crust & upper part of mantle

Earth’s Physical Structure – The Asthenosphere �plastic layer of the mantle on which the tectonic plates move �made of solid rock that flows very slowly

Exploring the Earth – Using Seismic Waves GR #4 � same waves that travel through Earth’s interior during an earthquake � use seismic waves to learn about Earth’s interior ◦ altered by the nature of the material through which it travels ◦ changes in speed & direction measured when passing through different layers

ACTIVITY: Earth’s Structure Foldable

BELLRINGER � How is heat transferred? � What causes c onvection currents in the Earth’s mantle?

Convection � Heat transfer caused by differences of temperature & density within a fluid � Liquid/gas is heated particles move faster � Particles spread apart, taking more space and density decreases

Convection: How is heat transferred? � Heating ◦ Particles move faster ◦ Spread apart taking up more space ◦ Density decreases � Cooling ◦ ◦ Particles slow down Settle closer together Density increases Particles sink

VIDEO: Convection Currents • Flow that transfers heat within a fluid • Heating & cooling changes fluid’s density • Force of gravity sets convection currents in motion

Where do convection currents occur? �Geosphere – plate tectonics �Atmosphere �Hydrosphere – wind - water

Convection Currents – Geosphere Source of Energy � Heat generated from radioactive decay of elements deep interior of the Earth ◦ Creates magma (molten rock) in asthenosphere ◦ Magma drives plate tectonics

Has the Earth always looked like this?

BELLRINGER Pangaea: Putting the pieces together Use the puzzle pieces to form a supercontinent ◦ A supercontinent describes a large landmass formed by all the continents coming together. ◦ You will be forming the supercontinent, Pangaea. ◦ Evidence supports theory that Pangaea may have existed approximately 225 -260 million years ago. ◦ Pangaea is from the Greek origin and means “all lands”

How Continents Move � Wegener’s Continental Drift ◦ Hypothesis that all continents once formed a single landmass called a supercontinent ◦ Began breaking apart 250 mya (Mesozoic Era)

THEORY: Plate Tectonics � theory that explains why & how continents move � study of the formation of features in Earth’s crust � Earth’s crust and upper mantle are broken into sections called plates � plates move around on top of the mantle like rafts

Two Types of Plates �Ocean plates below the oceans �Continental plates - plates below the continents

Plate Boundaries – Three Types � Divergent (constructive) � Convergent (destructive) � Transform (conservative)

Divergent Boundaries �a. k. a. constructive �Boundary between two plates that are moving apart or rifting �RIFTING causes SEAFLOOR SPREADING

Features of Divergent Boundaries �Mid-ocean �rift ridges valleys �fissure volcanoes

Age of Oceanic Crust § Where are ocean ridges located? § Where are the divergent boundaries? Courtesy of www. ngdc. noaa. gov Red color = youngest, dark blue = oldest

Iceland: � Iceland example of continental rifting has a divergent plate boundary running through its middle

Did you know that the Earth’s longest mountain range is underwater and is called the mid-ocean ridge? The Mid-Ocean Ridge system, shown above snaking its way between the continents, is more than 56, 000 kilometers (35, 000 mi) long. It circles the earth like the stitching on a baseball!

Convergent Boundaries �a. k. a. destructive �Boundaries between two plates that are colliding �There are 3 types… ◦ Continent-oceanic ◦ Ocean-ocean ◦ Continent-continent

Type 1: Ocean - Continent �Ocean plate colliding with a less dense continental plate

Subduction � Oceanic lithosphere subducts underneath the continental lithosphere � Oceanic lithosphere heats and dehydrates as it subsides � The melt rises forming volcanism � E. g. The Andes

Andes Mountains, South America

Type 2: Ocean-Ocean � The less dense plate slides under the more dense plate creating a subduction zone called a TRENCH � worlds deepest parts of the ocean are found along trenches ◦ E. g. The Mariana Trench is 11 km deep!

Type 3: Continent-Continent � continental plate colliding with another continental plate � Have Collision Zones: ◦ a place where folded and thrust faulted mountains form. ◦ Forms mountains (European Alps, Himalayas)

Himalayas

Transform Boundaries � a. k. a conservative � where plates slide past each other � earthquakes along faults Above: View of the San Andreas transform fault

San Andreas Fault, CA

ACTIVITY: Plate Tectonic GIZMO Website explorelearning. com

Continental Drift � Wegener’s Theory ◦ Hypothesis that all continents once formed a single landmass called a supercontinent ◦ Began breaking apart 250 mya (Mesozoic Era)

Fit of Continents Across the Atlantic Mountain ranges in South America line up exactly with those in Africa!

http: //evolution. berkeley. edu/evolibrary/images/history/fossils 3. gif Notice how fossils lined up across continents!

Amazing Facts: Did you know. . . that India was once in the Southern Hemisphere connected to Antarctica? . . . that North America was once surrounded by warm, tropical seas? . . . that Africa was once covered by glaciers, which were kilometers in thickness? . . . that the Sahara desert was once a tropical rain forest?

An example of the proof for changing climate: At one time, the area that is New Mexico was below the equator! As North America has drifted to different latitudes, changing climates were experienced. This shows the changes in the state of New Mexico.

Wegener: Doubted by ALL � could not find the force that was causing the continents to drift � could not convince anyone that continents could move � died in Greenland on an expedition; no one believed him Technology developed during the 1940’s changed all that!

Discovery of Seafloor Spreading

http: //platetectonics. pwnet. org/img/blocks. gif As the sea floor spreads, the lava cools according to the magnetic poles at the time. The rocks on the ocean floor have proved that the earth’s magnetic field sometimes reverses. The inner core flips and so the north pole moves to the southern hemisphere! The earth itself does not flip.

Animation of sea floor spreading Can you explain this diagram!?

This is a model of sea floor spreading at a divergent boundary called a mid ocean ridge.