Earth Systems

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Earth Systems

Big PictureObjective

MS-ESS2-3. Analyze and interpret data on the distribution of fossils and rocks, continental shapes, and seafloor structures to provide evidence of the past plate motions.

ESS2-1



Self Check• Upper Right Hand corner of notebook page

(just the number)• 4. I fully understood the lesson• 3. I got it, just need to look over a couple of

things.• 2. I could use a little more help to

understand.• 1. I have no clue as to what I need to know.



Section 1 Inside the Earth

10/01/14 Do Now

What do you think would weather down faster, a mountain or a hill made of rocks? Explain your answer.

Chapter F4



Tectonic Plates

Objectives• Identify the layers of the Earth by their chemical composition and properties

• Describe a tectonic plate.

• Describe the three forces thought to move tectonic plates.

ESS2-1



Tectonic Plates

Agenda: Today we will:•Day 1•Complete a do now•Watch a video on tectonic plates•https://www.youtube.com/watch?v=ELd3ebldSTs&feature=player_embedded•Learn about plate tectonics from teacher guided power point.

•Day 2•Complete Plate tectonics lab.•Exit ticket

ESS2-1



Tectonic Plates

Vocabulary

ESS2-1

• tectonic plates

• crust

• mantle

• core

• convergent boundary

• divergent boundary

• transform boundary




The Composition of the Earth• The Earth is divided into three layers—the crust, the mantle, and the core—based on the compounds that make up each layer.

• The Crust is the outermost layer of the Earth. The crust is 5 to 100 km thick, and is the thinnest layer of the Earth.

Chapter F4




The Composition of the Earth, continued

• There are two types of crust—continental and oceanic. Oceanic crust is thinner and denser than continental crust.

Chapter F4





• The Mantle is the layer of the Earth between the crust and the core. The mantle is much thicker than the crust and contains most of the Earth’s mass.

• The crust is too thick to drill through, so scientists must draw conclusions about the composition and other properties of the mantle from observations made on the Earth’s surface.

Chapter F4





• The Core is the central part of the Earth that lies below the mantle. The core makes up about one-third of Earth’s mass.

• Scientists think that the Earth’s core is made mostly of iron and contains smaller amounts of nickel but almost no oxygen, silicon, aluminum, or magnesium.

Chapter F4



Section 1 Inside the EarthChapter F4




Tectonic Plates

• Pieces of the lithosphere that move around on top of the asthenosphere are called tectonic plates.

• Tectonic plates consist of the crust and the rigid, outermost part of the mantle.

Chapter F4




Tectonic Plates, continued

• A Giant Jigsaw Puzzle Each tectonic plate fits together with the tectonic plates that surround it.

• The lithosphere is like a jigsaw puzzle. The tectonic plates are like the pieces of the puzzle.

Chapter F4




Tectonic Plates, continued

• A Tectonic Plate Close-Up The following Visual Concept presentation shows the Earth’s major tectonic plates and how they fit together.

• The presentation also illustrates what a tectonic plate might look like if you could lift it out of its place.

Chapter F4



Tectonic Plates

Click below to watch the Visual Concept.

You may stop the video at any time by pressing the Esc key.

Visual Concept

Section 1 Inside the EarthChapter F4




Tectonic Plates, continued• Tectonic plates “float” on the asthenosphere. The plates cover the surface of the asthenosphere, and they touch one another and move around.

• The lithosphere displaces the asthenosphere. Thick tectonic plates, such as those made of continental crust, displace more asthenosphere than do thin plates, such as those made of oceanic lithosphere.

Chapter F4



Section 2 Restless Continents

Wegener’s Continental Drift Hypothesis

• Continental drift is the hypothesis that states that continents once formed a single landmass, broke up, and drifted to their present locations.

• Scientist Alfred Wegener developed the hypothesis in the early 1900s.

Chapter F4




The Breakup of Pangaea• Wegener theorized that all of the present continents were once joined in a single, huge continent he called Pangaea.

• Pangaea is Greek for “all earth.”

• Pangaea existed about 245 million years ago.

Chapter F4



Continental Drift



Visual Concept

Section 2 Restless ContinentsChapter F4




Sea-Floor Spreading• Evidence to support the continental drift hypothesis comes from sea-floor spreading.

• Sea-floor spreading is the process by which new oceanic lithosphere forms as magma rises toward the surface and solidifies.

Chapter F4




Sea-Floor Spreading, continued• Mid-Ocean Ridges and Sea-Floor Spreading Mid-ocean ridges are underwater mountain chains that run through Earth’s ocean basins.

• These mid-ocean ridges are the places where sea-floor spreading takes place.

Chapter F4




Sea-Floor Spreading, continued• Evidence for Sea-Floor Spreading: Magnetic Reversals Some of the most important evidence of sea-floor spreading comes from magnetic reversals recorded in the ocean floor.

• Throughout Earth’s history, the north and south magnetic poles have changed places many times.

Chapter F4




Sea-Floor Spreading, continued• Magnetic Reversals and Sea-Floor Spreading Molten rock at the mid-ocean ridge contains tiny grains of magnetic minerals that act like compasses.

• These minerals align with the magnetic field of the Earth. When the molten rock cools, the record of these tiny compasses remains in the rock.

Chapter F4




Sea-Floor Spreading, continued• When the Earth’s magnetic field reverses, the magnetic mineral grains align in the opposite direction. The new rock records the direction of the Earth’s magnetic field.

• As the sea floor spreads away from a mid-ocean ridge, it carries with it a record of these magnetic reversals.

Chapter F4



Magnetic Reversals and Sea-Floor Spreading



Visual Concept




Tectonic Plate Boundaries• As scientists’ understanding of mid-ocean ridges and magnetic reversals grew, a theory was formed to explain how tectonic plates move.

• Plate tectonics is the theory that explains how large pieces of the Earth’s outermost layer, called tectonic plates, move and change shape.

Section 3 The Theory of Plate TectonicsChapter F4



Tectonic Plate Boundaries, continued

• A boundary is a place where tectonic plates touch. All tectonic plates share boundaries with other tectonic plates.

• The type of boundary depends on how the tectonic plates move relative to one another.





There are three types of tectonic plate boundaries:

• Convergent Boundaries

• Divergent Boundaries

• Transform Boundaries




Tectonic Plate Boundaries, continued• When two tectonic plates collide, the boundary between them is a convergent boundary.

• What happens at convergent boundaries depends on the kind of crust at the leading edge of each tectonic plate.




Tectonic Plate Boundaries



Visual Concept




• When two tectonic plates separate, the boundary between them is called a divergent boundary.

• New sea floor forms at divergent boundaries.

Section 3 The Theory of Plate Tectonics


Chapter F4



• When two tectonic plates slide past each other horizontally, the boundary between is called a transform boundary.

• The San Andreas Fault in California is an example of a transform boundary.

Section 3 The Theory of Plate Tectonics


Chapter F4



Causes of Tectonic Plate Motion



Visual Concept




Possible Causes of Tectonic Plate Motion

• What causes the motion of tectonic plates? This movement occurs because of changes in the density within the asthenosphere.

• The following Visual Concept presentation examines three possible driving forces of tectonic plate motion.




Tracking Tectonic Plate Motion• Tectonic plate movements are so slow and gradual that you can’t see or feel them. The movement is measured in centimeters per year.

• Scientists use a system of satellites called the global positioning system (GPS) to measure the rate of tectonic plate movement.




Newton’s Second Law of Motion, continued



Visual Concept




Exit Ticket

•What are tectonic plates and what makes them move?



Homework

• Handout on Plate Tectonics

Earth Systems

Documents

Transcript of Earth Systems