Unit 1 Notes

The Geosphere

Unit Objectives EEn.1.1.3 Explain how the sun produces energy which is

transferred to the Earth by radiation. EEn.2.1.1 Explain how the rock cycle, plate tectonics, volcanoes,

and earthquakes impact the lithosphere. EEn.2.1.2 Predict the locations of volcanoes, earthquakes, and

faults based on information contained in a variety of maps. EEn.2.1.3 Explain how natural actions such as weathering,

erosion (wind, water and gravity), and soil formation affect Earth’s surface.

EEn.2.1.4 Explain the probability of and preparation for geohazards such as landslides, avalanches, earthquakes and volcanoes in a particular area based on available data

EEn.1.1.3 How Stars Produce Energy

Combustion vs Burning

• Burning is a type of combustion where flames can be seen– Most of the energy from burning is converted into

light energy

• Combustion is a reaction that takes place without flames so there is more energy in the form of heat produced

Nuclear Fission vs Nuclear Fusion

• Nuclear Fusion – nuclei combine

• The way in which the Sun produces energy

• Nuclear Fission – nuclei split

• Process used in nuclear power plants

Electromagnetic Spectrum

Filtering the EM Spectrum• Not every wavelength emitted by stars

(including our Sun) reaches Earth’s surface

Energy Transfer• Conduction – energy is

transferred when particles touch each other

• Convection – energy is transferred through fluids (liquids and gasses)

• Radiation – energy is transferred by electromagnetic waves

Energy Transfer in Stars1. Nuclei collide in the core releasing a photon2. Photon energy is transferred from one particle to the

next through conduction3. Energy rises to the surface by convection

4. Energy is then radiated out into space

Solar Forces in Balance• Stars are held together

by gravity. • Gravity tries to

compress everything to the center.

• Thermal and radiation pressure try to expand the star layers outward to infinity.

EEn.2.1.1The Rock Cycle, Plate Tectonics, Volcanoes and Earthquakes

The Rock Cycle

Forces & Materials in the Rock Cycle

• Forces– WEATHERING and EROSION– HEAT and PRESSURE– COMPACTION and CEMENTATION– MELTING and COOLING

• Materials– IGNEOUS ROCK– SEDIMENTARY ROCK– METAMORPHIC ROCK– MAGMA/LAVA– SEDIMENTS

ROCK CYCLE

• Energy is required for rocks to change from one type to the next

• Sedimentary = external energy from the Sun to drive weathering and erosion

• Igneous & Metamorphic = energy in the form of heat from the Earth’s core

Plate Tectonics

Earth’s Layers• Crust is thin and rocky

– Oceanic = younger rocks– Continental = older rocks

• Mantle 82% of Earth’s volume is found here– Lithosphere – a strong layer under

the upper mantle– Asthenosphere – a softer layer under

the lithosphere• Core

– Outer – liquid due to extreme heat– Inner – solid due to intense pressure

• Compostion of layers due to density of materials; – heavier elements in the core– lightest elements in the crust

Continental Drift

• Theory prior to plate tectonics

• Proposed by German scientist Alfred Wegener in 1915

• States that the continents had once been joined to form a single supercontinent

• Pangaea!!!!

Evidence• The continental

puzzle

• Matching fossils

• Similar rock types and structures

• Similar ancient climates

A New Theory• Wegener’s theory was replaced in the 1950s and 60s

by plate tectonics

• Takes in to account tectonic activity and mantle convection

Causes of Plate Tectonics• Mantle Convection

– Transfer of thermal energy by the movement of heated matter in the mantle

• Rising mantle – divergent boundary• Falling mantle- convergent boundary

– Push and Pull• Ridge push• Slab pull

Earth’s Major Plates

• The lithosphere is divided into tectonic plates

• These plates move and continually change shape and size

Types of Boundaries• CONVERGENT

– Where 2 tectonic plates are moving together• Creates a subduction zone

– Trenches, island arcs and folded mountains• DIVERGENT

– Where 2 tectonic plates are moving apart– Volcanism, earthquakes and high heat flow

• TRANSFORM– Where 2 tectonic plates are sliding horizontally past

one another– Long faults and shallow earthquakes

Convergent = Destroy

oceanic-continental continental-continental oceanic-oceanic

• Form either a subduction zone or a continental collision

• Earthquakes and volcanoes are common

• Oceanic-Continental = Cascade Mountain Range

• Continental-Continental = Himalayas

• Oceanic-Oceanic = Mariana Trench, Japan, Aleutian Islands

Divergent = Create• Black Hills, SD

• East African Rift Valley

• Red Sea

• Mid-Atlantic Ridge– Seafloor spreading

Transform = Conserve

San Andreas Fault in California most famous

Earthquakes

https://www.youtube.com/watch?v=_gE0UnyA2kI

• Earthquakes occur because of the forces of plate tectonics – Place where two tectonic plates meet form a

boundary; faults are found at these boundaries

• Earthquake waves can travel around the world through the different layers of the Earth

• There are two parts – the focus and the epicenter

Two Parts of an Earthquake

• Focus: Point within the Earth where the Earthquake starts.

• Epicenter: On the surface above the epicenter.

Types of Faults Reverse Fault/Thrust Fault = Convergent Boundary

Normal Fault = Divergent Boundary

Strike-Slip Fault = Transform Boundary

Two Types of Shocks• Aftershock

– Follows a major earthquake (usually smaller than original quake

• Foreshock– Before an earthquake– Can happen years/days

before an earthquake

How do we measure waves?

Seismograph

Two Types of Waves• Surface Wave

– Travel along the Earth’s surface

• Body Waves– P wave: push/pull wave

through rocks (1st)– S Wave: shake particles

at right angles (2nd)

P and S Waves

Finding the Center of an Earthquake

• Use measurements from three seismic stations

• Data is used with a distance – time graph to triangulate the earthquake’s origin

Measuring Destructive Force• Intensity (Mercalli Scale)

– Amount of shaking– Measured at a specific

location

• Magnitude (MMS)– amount of energy released

at the focus

The Scales• Richter Scale

– Based on the amplitude (height) of the largest wave

– Replaced by Moment Magnitude Scale (MMS)

• Mercalli Scale– Amount of displacement

from the fault

Types of DestructionSeismic Vibrations Landslides

Tsunamis Fires

Volcanoes

Factors Affecting Eruptions• Primary Factors

– Magma composition• More silica = thicker lava• More iron/magnesium =

thinner lava– Magma temperature– Amount of dissolved gases

– Viscosity – a substance’s resistance to flow

Where Do Volcanoes Form?• Divergent boundaries

– Magma chambers are close to the surface due to the plates moving apart

• Convergent boundaries– Subducted plate melts and forms

magma chambers under the volcano

Types of Volcanoes• Shield Volcanoes

– Largest type– Form at divergent

boundaries

• Cinder Cones– Small cones of telphra– Form near shield volcanoes

• Composite Cones– Made of alternating layers

of lava and telphra– Form at convergent

boundaries

Other Volcanic Landforms

• Necks & Pipes – How magma gets through the volcano

Calderas – a large depression in a volcano

Lava Plateaus

Mt. Saint Helens Eruption May 18, 1980

https://www.youtube.com/watch?v=SJA27Bp1q58

A Supervolcano?!?!?

Where could it be?

Yellowstone National Park

Wyoming, United States

https://www.youtube.com/watch?v=DS3RA7NdVKE

Een.2.1.2 Predicting Earthquakes and Volcanoes from Maps

Predicting Earthquakes

• Short range – very difficult to determine exactly when and where an earthquake will happen, but seismographs give clues

• Long range forecasts predict whether an earthquake is likely to occur in a given area within 30 to 100 years.

• Because earthquakes and volcanoes occur at plate boundaries, areas along faults are most likely to experience these hazards

EEn2.1.3 Weathering, Erosion and Soil Formation

Mechanical vs Chemical Weathering

Mechanical•Occurs when physical forces break down rocks – temperature & pressure•Three process:

– 1.) Frost Wedging– 2.) Unloading– 3.) Biological Activity

Chemical•Transformation of a rock from one form to another

– Water (hydrolysis), oxygen (oxidation), carbon dioxide (carbonic acid), acid rain

•Water: A major factor!

Mechanical Weathering

Chemical Weathering

Rate of Weathering

• Three factors are:

1.) Rock Characteristics: the physical way a rock looks

2.) Climate: Temperature and moisture

3.) Differential Weathering: Different parts of rock mass weather at different rates.

Just a little soil information

• An important product of weathering

• Supports growth of plants

• Four major components:– 1.) Mineral Matter: about 45% of the matter in soil– 2.) Organic Matter: 5% (decayed things)– 3.) Water: 25% water– 4.) Air: 25% air

How Soil is Formed

• Requires 5 things:– parent material, topography, climate, organisms, time

• Creates soil horizons

Topography

Climate

• Cool, dry, sparse vegetation– Predominantly physical weathering

• Warm, wet, abundant vegetation– Increased chemical weathering

The Soil Profile• Soil varies in

texture, composition, structure, and color at different levels.– A Horizon – Topsoil– B Horizon – Subsoil– C Horizon –

Bottom true to the parent material

– R Horizon - Bedrock

Erosion• Movement of weathered material from one

location to another

• Rates of Erosion: – More plants, grass, and trees helps to hold the soil in

place.– Human activity that removes these things help to

speed up erosion.

EEn2.1.4Mass Movement and Geohazards

Mass Movement

What it is and its Triggers

Water Saturating surfaces creating mudflows

Over-steepened Slopes Water cuts under the bank of a river

Removal of Vegetation Taking away plants and roots

Earthquakes Shake loose soil creating a landslide

• The transfer of rock and soil down slope due to gravity and caused by weathering and erosion

Types of Mass Movement• Based on the kind of material, how it moves and the

speed of the movement.

• Rockfall = rocks fall from a steep slope• Slides = land sides down suddenly

– High mountain areas• Slumps = downward movement of a block of material

in a curved surface • Creep = the slowest form of movement• Flows = mass amounts of movement

– 2 types:• Mudflow – Moves quickly• Earthflow – Moves slowly

Geohazards

Geohazards• Landslides• Mudslides• Avalanches• Falling rock• Volcanoes• Earthquakes• Floods

Geohazard Protections• It is impossible to prevent geohazards or to

know exactly where and when they will occur

• Can use levees, damns, wire netting, breaks and special building codes to help limit damage and save lives

• Having a disaster preparedness plan in place is extremely important for EVERYONE!

Geohazard Protection

Unit 1 Project