Lecture 2 Earth System and Plate Tectonics

Earth System and Plate Tectonics

Atmosphere

Gas surrounding earth’s surface

Geosphere

Solid earth from surface to centre

Hydrosphere and Crysophere

liquid water and ice in all other realms

Biosphere

all types of living organisms

What sets the stage for hazards and disasters?

Earth’s dynamism

T/F Magnetic poles and geographic poles are perfectly alligned.

False

Magnetic field is distorted by

Solar winds (Charged Particles)

What deflects most of the Sun’s charged particles?

Magnetic field.

Weather vs Climate

Weather - short-term atmospheric conditions

Climate - long-term atmospheric conditions

When are clouds created?

Air’s water vapor changes state.

T/F 70% of earth is covered by liquid water. 97% salty, 3% fresh.

True

T/F 70% of the geosphere’s surface is under the ocean as seafloor.

True.

Ocean floor includes

Flat plains, ridges, and trenches.

Both land and oceans contain

Tectonic activity, faults, volcanism

T/F Internal energy melts rock, which may form a volcano.

True

How does internal energy generate earthquakes?

Internal energy drives plate movement, plate movement generates earthquakes

Where does internal heat come from?

1. Leftover heat from planet formation

2. Heat from decay of radioactive atoms

External energy

Electromagnetic radiation from the sun

• photosynthesis.

What are forms of energy in the earth system?

• External Energy

• Gravity

• Convection

What does gravity cause?

• land movement

• rainfall

• riverflow

Where is convection seen?

Atmospheric and Ocean circulation and plate movement.

What are the crust, mantle, and core based on?

Compositional Differences

What are the lithosphere and asthenosphere based on?

Rigidity differences

Which is hot enough to undergo plastic flow?

a. Lithosphere

b. Asthenosphere

b. asthenosphere

The lithosphere is ____ and consists of Earth’s _____ and _____ _______

Rigid, Crust, Upper Mantle.

Evidence for Pangea

• matching coastlines across the atlantic ocean

• mountain belts separated by oceans aligned

• matching fossils on continents separated by oceans

• aligned sedimentary rocks follow climate belts across continents.

• aligned contiguous glacial evidence across continents.

When did Pangaea Break Up

Late Jurassic

How does the mantle allow lithospheric plates to move?

Hot mantle flows like plastic

Where do faults form and what do they generate?

At plate boundaries, Earthquakes

Active vs Passive Continental Margin

Active - continental shoreline at a tectonic plate boundary

Passive - not at a plate boundary

What are the 3 types of plate boundaries?

1. Divergent Boundaries

2. Convergent Boundaries

3. Transform Boundaries

Geologic hazards are common along which types of plate boundaries?

All of them.

Where are the youngest plates on the ocean floor?

Occur on divergent boundaries (ridges / spreading centres) where new crust forms

Where is the oldest crust on the ocean floor?

Along trenches in subduction zones where plates converge

Earth’s internal heat comes from two sources, what are they?

1. leftover heat from planet’s formation

2. heat from decay of radioactive atoms

What are additional forms of energy in the earth system?

→ external energy (electromagnetic radiation from the sun)

→ gravity (causes land movement, rainfall, river flow)

→ convection (seen in atmospheric and ocean circulation, and plate movement)

An island arc forms when an ocean plate ______ beneath an ocean plate

Subducts

When does a continental arc form?

When an ocean plate subducts beneath a continental plate.

What do transform faults link?

The ends of mid-ocean ridges

When do rift basins form?

When continental lithosphere stretch and break apart, rift basins form due to faulting.

T/F Volcanic Eruptions create hazards in rift zones.

True

If a rift splits a conitnent, what is created?

Mid-ocean ridge

Inactive rift remnants become

Passive Continental Margins

Hot Spot Volcanoes

Form above mantle plumes and are not caused by plate interactions

What happens as a plate moves over a mantle plume?

→ Mantle plumes are fixed

→ Plate moves

→ Hotspot volcano moves off mantle plume as plate moves.

Plume stays fixed while the plate moves, causing volcanoes to move off the plume.

What are seamounts and volcanic island chains?

Tracks left by hot-spot volcanism as plates move over fixed mantle plume

Uniformiatarianism

• present is key to the past

• modern physical processes also occurred in past at same rate.

Why is plate tectonics a grand unifying theory?

Combines continental drift and seafloor spreading theories.

T/F Magnetic field lines point inward at the south magnetic pole and outward at north magnetic poles.

False.

Which of the following is not a major Earth system?

a. atmosphere

b. hydrosphere

c. biosphere

d. ionosphere

e. geosphere

d. Ionosphere

T/F Brittle deformation occurs under high temperature and pressure conditions, whereas plastic deformation occurs at high pressure and temperature.

False.

→ Brittle deformation @ low pressure and low temperature

→ Plastic deformation @ high pressure and high temperautre

What are the four eons in time scale from earliest to latest?

Hadeon

Archeaon

Proterozoic

Phanerozoic

Which of the following is incorrect?

a. Liquid water covers 70% of earth’s surface

b. Most of surface water is salty ocean water

c. Both land and oceans contain tectonic activity

d. Most earthquakes and volcanoes are generated by plate movement

e. Earth’s centre is as hot as the sun’s surface

a. Liquid water covers 70% of earth’s surface

b. Most of surface water is salty ocean water

c. Both land and oceans contain tectonic activity

d. Most earthquakes and volcanoes are generated by plate movement

e. Earth’s centre is as hot as the sun’s surface

there’s are all correct! there must be typo here!!!!!

The two most abundant gas molecules in the atompshere are

a. Nitrogen and Oxygen

b. Carbon Dioxide and Oxygen

c. Hydrogen and Nitrogen

d. Methane and Oxygen

a. Nitrogen and Oxygen

Which of the following is incorrect?

a. youngest oceanic crust occurs at subduction zones

b. transform plate boundaries occur in continents and oceans

c. oldest oceanic crust occurs at subduction zones

d. the asthenosphere is hot enough to undergo plastic flow

e. earth’s internal energy drives plate movement

a. youngest oceanic crust occurs at subduction zones.

• youngest oceanic crust forms at divergent boundaries, in spreading centres (ridges, divergent)

• oldest oceanic crust occurs at subduction zones (trenches, convergent))