Earth’s Dynamic CrustAim: What is meant by “Dynamic

Crust” and what evidence can we observe to support it?

Do Now1. Open your review books to p. 2452. In Figure 12-1 Diagram D label layers

2,3,4, and 5 using your scheme for sedimentary rock identification (ESRT)

3. Which of these numbered layers do you think is the oldest, why?

HW: R+H 244-245, A+E 1-8

Uniformitarianism – The processes that shaped the earth we see today are still occurring and will continue to occur

Superposition – the oldest rock layers will be the deepest in the Earth (upset only by overturning and thrust faults)

Original Horizontality - sedimentary rocks and extrusive igneous rocks form in horizontal layers called strata

Three Forces Which Cause Crustal DisturbancesCompression – two strata moving

towards one another, causes reverse faults

Tension – two strata moving away from one another, causes normal faults

Shearing- two strata moving laterally with respect to one another, causes lateral faults

Rock Layers which are no longer show original horizontalitiy are referred to as disturbedThere are three kinds of

disturbed strata1. Folded – bent or curved layers

Occurs Because Rock Types Are Ductile – Bend Easily

Anticline

Syncline

2. Tilted Strata – rocks appear diagonal or slanted

3. Faulted Strata – a break has occurred in the horizontal layer

This occurs because the rocks are brittle or easily broken

All three of these types of disturbed strata are evidence for crustal movement

There is one more piece of evidence…Eurypterus Remipes (and other fossils)

◦Marine fossil found on top of mountains in NYS◦Shows evidence of crustal uplift

So…What do you think we mean

when we say “Dynamic Crust”What have we learned about

today that can support this?

Plate Tectonics 3/22/11 Aim: What are the three types of plate boundaries

and how have they formed the world we see today? Do Now:

1. Using the diagram below please label the following; disturbed or undisturbed, oldest rock layer, foot wall, hanging wall, the stress (tension, compression, or shearing), type of fault, property of the rocks (brittle or ductile)

2. What other evidence of crustal movement did we see yesterday?

HW: Finish Crustal Activity Lab

Continental Drifthttp://www.youtube.com/watch?v

=hSdlQ8x7cukContinental Drift – the movement

of the Earth’s continents relative to one another

Plate Tectonics – Earth’s lithosphere is broken up into sections which move and produce the major changes in the Earth’s surface

Diverging Boundaries

Seafloor spreading creates new crust

Converging Boundaries

Subduction or crustal uplift – Island Arcs or mountain ranges

Transform Boundaries

Lateral tension builds up in the crust and is released periodically causing earthquakes

Aim: Features that we can see at each plate boundary and evidence for continental driftDo Now: 1. Name each of the three plate boundaries, the kind of

stress which forms them, and the geological features seen at each one

2. Please take out your Review Book and turn to page 262

HW: Finish the Crustal Activity Lab and Plate Tectonics Worksheet

3/23/10

Island Arcs vs. Island Chains

Island ArcsOccur along

Convergent plate boundaries

Formed by rising magma from melted subducting plate.

Ex. The Aleutian Islands

Island ChainsOccur over Hot

Spots in the Earth’s mantle.

Formation of the Hawaiian Islands

Four Pieces of Evidence That Support Continental Drift and Plate Tectonics

1. Puzzle Like Fit of the Continents2. Matching Fossils on Different Continents

4. Glacial Deposits3. Matching Rock Formations

Aim: Look at rock patterns and how they relate to plate tectonicsDo Now:

1.Quiz on Plate Tectonics: Get into Test Formation

HW – R&H 259–267, A&E 42-68

3/24/11

Magnetic ReversalIn a diverging oceanic-oceanic

plate boundary cooling rocks orient themselves to magnetic north.

Over time magnetic north has switched from the geographic north pole to the geographic south pole and back again.

Geologists can match these orientations on either side of the plate boundary to show evidence of Seafloor Spreading

Aim: What is an Earthquake?Do Now:1. Graph the relationship between rock

age and distance from a mid-ocean ridge. 2. If the Pacific Plate is moving generally

northwest than which Hawaiian Island is the youngest

3. What is the relationship between earthquakes and tectonic plates?

4. Take out a clean sheet of paperHW: View the two animations on

Earthquake Waves posted on “Mr. Jantzen’s Earth Science Videos and Animations” (Test Friday)

3/28/11

P-WavesAlso called primary

waves or compressional waves

Faster so first to arrive

Travel through all materials

Comes from the focus

S-WavesAlso called secondary

waves or shear waves because they cause most of the shaking

Slower so always arrive after P-Waves

Travel through SOLIDS ONLY

Comes from the focus

Surface Waves• Slowest kind of wave which travels along the

surface of the earth starting at the epicenter• Travels like ripples in a pond and can cause

significant damage

Seismograph

Seismogram

PracticeFigure out the difference between

the P and S wave arrival times on the board for each seismogram.

If the difference in P and S wave arrival times increases with distance from the epicenter, then which seismogram came from the seismograph station closest to the earthquake?

Aim: How do we use P and S Waves to locate an earthquake?Do Now:1. From your homework last night explain

how the P and S waves differed in the way they shook the houses

2. Look for a chart in your reference table that resembles the distance and travel time of seismic waves plotted in Earthquake waves video 2

3. Take out a clean sheet of paperHW: R&H 246-253 A&E 9-28, Make sure to

bring laptops to class tomorrow. (Test Friday)

Date: 3/29/11

Practice Problems1. How long does it take for:

a. an S wave to travel 7,000 kilometers (km)b. a P wave to travel 2,600 km

2. If the P wave arrives 5 minutes and 20 seconds after the earthquake actually occurs, how far away from the epicenter are you? When will the S wave arrive?

3. What is the difference in arrival time between the P and S waves if you are 4,400 km away from the epicenter.

4. a. What is the distance to the epicenter if the P and S wave arrive 3 minutes and 20 seconds apart. b. How long did it take the P wave to get there?c. If the P wave arrived at 2: 45 pm when did the earthquake occur

Locating EpicentersOne seismic

station can give us the distance

Two seismic stations can give us distance and direction

Three seismic stations can pinpoint an exact location for an epicenter

Aim: What causes a tsunami?

Do Now:1. What is a tsunami?2. Take out your laptops3. Go to the class website4. Look for the new page titled

“Tsunami Detectives”HW: Fill in your “Tsunami

Detective” Worksheet for the recent tsunami in Japan

Study for Friday’s Test: Topic 12

Date: 3/30/11

Learning Objectives1. What causes a

tsunami?2. How are tsunamis

related to the earthquakes we studied yesterday and how are they related to the concept of a dynamic crust?

Aim: What does the Earth’s interior look like below the crust?Do Now1. How can earthquake magnitude be

measured?2. What are some common types of

volcanoes3. What are some things we can do to

prepare for a natural disaster? (Earthquakes, volcanoes, tsunamis)

4. If we cannot physically drill to the center of the earth, how can we know what it looks like?

HW: R&H 255-258 A&E 29-41Test Tomorrow STUDY

Richter Scale Rated 1 to 10 Measures EQ magnitude

so each EQ has only one value.

Largest EQ ever recorded was an 9.5 on the Richter Scale (Chile 1960)

Mercalli Scale Rated by intensity 1 to 12 Based on what you would

feel in one area so one EQ can have many intensities

1 detected only by seismographs and 12 is total destruction

Volcanoes

Cinder ConeComposite

Emergency PlanningEarthquakes cannot be

predicted If you ever find yourself

in an earthquake “drop, cover, and hold” under a strong object, you can also practice EQ drills

Proper building codes are required in areas prone to EQ’s such as type of rock underneath the building and materials used to construct the building

Always have a disaster plan

Volcanoes can be predicted by measuring the small earthquakes leading up to an eruption.

Always have a disaster plan

Tsunami warnings may offer a few hours notice.

Get to higher ground and find a secure structure

Always have a disaster plan

A Model of the Earth’s InteriorProperties of the

earth’s interior were inferred by studying seismic waves

A wave’s speed will increase if the pressure or the density of the material it travels through are increasing

As the properties of a material change the wave is bent or refracted.

Reference Tables Page 10

The Moho is a discontinuity between the crust and the mantle at which waves refract.

The asthenosphere is the solid part of the mantle with the ability to flow (plastic), this is where convection cells originate.