Joy of Science Experience the evolution of the Universe, Earth and Life

Unless otherwise noted, all pictures are taken from wikipedia.org

•  Review •  Introduction •  Main contents •  Quiz

Review 1

�  Which is not included in objects of the solar system?

A. Sun B. Quasars C. Moons D. Comets E. Asteroids F. Planets

Review 1

�  Which is not included in objects of the solar system?

A. Sun B. Quasars C. Moons D. Comets E. Asteroids F. Planets

Review 2

�  Which of the following is the largest planet? A. Neptune B. Jupiter C. Uranus D. Saturn E. Mars

Review 2

�  Which of the following is the largest planet? A. Neptune B. Jupiter C. Uranus D. Saturn E. Mars

Review 3

�  Which of the following is a terrestrial planet?

A. Mars B. Neptune C. Saturn D. Uranus E. Jupiter

Review 3

�  Which of the following is a terrestrial planet?

A. Mars B. Neptune C. Saturn D. Uranus E. Jupiter

Review 4

�  A small piece of space debris that reaches the surface of the Earth is (another name for it is “shooting star” or “falling star”)

A. a meteor B. a meteorite C. an asteroid D. a comet

Review 4

�  A small piece of space debris that reaches the surface of the Earth is (another name for it is “shooting star” or “falling star”)

A. a meteor B. a meteorite C. an asteroid D. a comet

Review 5

�  The small rocky bodies found in a broad band between Mars and Jupiter are

A. meteorites B. meteors C. asteroids D. comets

Review 5

�  The small rocky bodies found in a broad band between Mars and Jupiter are

A. meteorites B. meteors C. asteroids D. comets

The Earth - Experience the evolution of the Earth: the restless Earth

Today’s Keywords volcano, earthquake, plate tectonics, mantle convection, plate boundaries, seismology

May 18, 2012

Introduction Recall the structure and formation of the solar system! �  After the most of Earth’s mass have accumulated in the beginning,

- Heavy, dense materials sank under gravity toward the center of the earth - Lighter, less-dense materials floated to the top à Let us take a closer look at Earth’s internal structure �  Other terrestrial planets also have a distinctively layered structure

by the result of the process represented above

�  Only Earth has dynamic and restless activities originated by energy from the hot, dense core

à What dynamic aspects of the Earth are there?

à What is the theory to explain Earth’s dynamic features?

1. Introduction

Inner structure of the Earth

From the center of the Earth, �  Core: iron and nickel metal

- Inner core: over 5000 deg. C temperature, very high pressure, solid state - Outer core: lower pressure, liquid state �  Mantle: Charged elements of oxygen, silicon, magnesium, and iron.

Much denser forms of similar composition to surface rocks due to high pressure. Dense fluid of rocks. �  Crust: Made of lightest materials. Less than 10 km thickness in

parts of the oceans, as much as 70 km beneath parts of the continents. We think of it as a sold surface of Earth.

1. Introduction

Inner structure of the Earth: Picture 1. Introduction

Atmospheric structure

Dynamic aspects of Earth

�  The case of disappearing mountains �  Volcanoes and Earthquakes �  Movements of continents àPrimary continental model on Earth: Pangaea

1. Introduction

Primary continent on Earth: Pangaea 1. Introduction

Evolution of continents on Earth from Pangaea

1. Introduction

Plate Tectonics: a unifying View of Earth

Plate Tectonics �  Compelling model of dynamic Earth �  Explains many of Earth’s large-scale surface features and related

phenomena

Central idea of the theory �  Earth’s surface is broken up into some large pieces called tectonic

plates �  Earth plate is composed of Crust and part of upper Mantle �  Ocean plates: 8-10 km thickness with dense rock

Continent plates: average 35 km thickness with lower dense rock

2. Plate tectonics

Tectonic Plates Plates �  a

2. Plate tectonics

Mantle Convection: continents move as a result of the forces generated by mantle

�  Earth behaves something like a giant spherical stove, with burners on the inside and circulating rocks bringing the heat to the surface! �  Effects of mantle convection to Earth’s plates

The top of mantle rocks encounter relatively thin, week plates à Along oceanic ridges brittle plates crack à Lava erupts à Seafloor spreading starts à All other plates motions start

Mantle

convection volcanoes, earthquakes, movement of continents

2. Plate tectonics

core

Mantle Convection: picture

2. Plate tectonics

Plate Boundaries: determine much of geological character of Earth’s surface

1.  Divergent plate boundaries

2.  Convergent plate boundaries 3.  Plate transform boundaries

2. Plate tectonics

Plate Boundaries

1. Divergent plate boundaries �  Spreading zone of crustal formation �  Motion of magma pushes two adjoining

plates farther away from each other. Results are, 1) A chain of mountains formed by volcanic motions 2) New pate materials produced by newly erupted melted materials 3) Shallow earthquakes with low energy

2. Plate tectonics

Plate Boundaries

2. Convergent plate boundaries �  Continent - Continent

�  Ocean – Ocean

�  Ocean – Continent

2. Plate tectonics

2.2. Plate Boundaries 2. Convergent plate boundaries �  Continent - Continent

: two continents collide and ride on top of both à high, jagged mountain chain

Ex) The Himalayas

2. Plate tectonics

2.2. Plate Boundaries

2. Convergent plate boundaries �  Ocean – Ocean: both plates converge

à Deep ocean trench à Melted materials become magma, then rise up to the surface à Eruptions of lava build a chain of volcanic islands adjacent to the trench

2. Plate tectonics

2.2. Plate Boundaries

2. Convergent plate boundaries

�  Ocean – Continent : denser oceanic plate converge into beneath continental plate, continental material is crumpled into coastal mountains. à volcanic mountains parallel to coast, trench

2. Plate tectonics

Plate Boundaries

3. Plate transform boundaries �  Two plates slide each other

not smoothly Results are, 1) Earthquake 2) No mountain building 3) No volcanic activities

2. Plate tectonics

Plate Boundaries

3. Plate transform boundaries �  Two plates slide each other

not smoothly Results are, 1) Earthquake 2) No mountain building 3) No volcanic activities

2. Plate tectonics

San Andreas Fault in California

San Andreas Fault from Google maps

Plate and Volcanism

�  Divergent plate boundaries: Main source of new crustal formation along volcanic spreading ridges

�  Convergent plate boundaries: Volcanoes are common near subduction zones. “(Pacific) Ring of Fire” is a dramatic string of volcanoes.

�  Hot spots: Chimney like columns of rising hot rocks from lower mantle or even the core-mantle boundary (cf. bubbles coming to the surface in water being heated on a stove). A chain of volcanoes is formed as a tectonic plate slowly moves over a fixed hot spot (ex. the Hawaiian islands)

3. Volcanism

Plate and Volcanism

�  Convergent plate boundaries: Volcanoes are common near

subduction zones. “(Pacific) Ring of Fire” is a dramatic string of volcanoes.

�  Hot spots: Chimney like columns of rising hot rocks from lower mantle or even the core-mantle boundary (cf. bubbles coming to the surface in water being heated on a stove). A chain of volcanoes is formed as a tectonic plate slowly moves over a fixed hot spot (ex. the Hawaiian islands)

3. Volcanism

Plate and Volcanism

�  Hot spots: Chimney like columns of rising hot rocks from lower mantle or even the core-mantle boundary (cf. bubbles coming to the surface in water being heated on a stove). A chain of volcanoes is formed as a tectonic plate slowly moves over a fixed hot spot (ex. the Hawaiian islands)

Hawaiian Islands

3. Volcanism

Hot spot

Plate and Volcanism

�  Hot spots: Chimney like columns of rising hot rocks from lower mantle or even the core-mantle boundary (cf. bubbles coming to the surface in water being heated on a stove). A chain of volcanoes is formed as a tectonic plate slowly moves over a fixed hot spot (ex. the Hawaiian islands)

Hawaiian Islands

3. Volcanism

Hot spot Picture taken http://library.thinkquest.org

Earthquake

�  Earthquakes may be felt near any plate boundary. �  Minor shallow ones occur near divergent plate boundaries as two

plates move apart. �  Strong earthquakes occur near subduction zones. (many of

Japan’s) �  Earthquakes along the transform plate boundaries in the USA. �  Occasional ones in the middle of plates

è The origins of these earthquakes are still not fully understood!

4. Earthquake

Seismology: exploring Earth’s interior with earthquakes

�  The idea of seismology Some of waves of vibrational energy travel through Earth’s center, others move along the surface, and still others bounce off layers deep within the planet.

5. Seismology

Seismology: exploring Earth’s interior with earthquakes

5. Seismology

Two principal seismic waves P-wave (Primary: longitudinal)

: Travel through any time of material at speed of sound S-wave (Secondary: transverse) : Typically follows P-wave. Travel only through solids at usually 60% of speed of P-wave.

5. Seismology

Quiz 1

�  The energy for the movement of tectonic plates comes from A. the Sun B. outer space C. the mantle D. the crust

Quiz 1

�  The energy for the movement of tectonic plates comes from A. the Sun B. outer space C. the mantle D. the crust

Quiz 2

�  A subduction zone is characteristic of A. a fault zone B. a transformed plate boundary C. a divergent plate boundary D. a convergent plate boundary

Quiz 2

�  A subduction zone is characteristic of A. a fault zone B. a transformed plate boundary C. a divergent plate boundary D. a convergent plate boundary

Quiz 3

�  The subsurface molten material in the mantle that enters a volcano is called

A. crustal material B. fault flow C. magma d. lava

Quiz 3

�  The subsurface molten material in the mantle that enters a volcano is called

A. crustal material B. fault flow C. magma d. lava

Quiz 4

�  The study of earthquake waves is called A. continentalism B. seismology C. geology D. volcanism

Quiz 4

�  The study of earthquake waves is called A. continentalism B. seismology C. geology D. volcanism

Next class is on Earth cycles: Chapter 14