Plate Boundaries. Remember: Earth Structures Lithosphere Asthenosphere.
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Transcript of Plate Boundaries. Remember: Earth Structures Lithosphere Asthenosphere.
Plate Boundaries
Remember: Earth Structures
LithosphereAsthenosphere
Plate Tectonics
1. Plates are moving in different directions at different speeds.
2. Movement caused by convection in asthenosphere.
Plate boundary = place where two plates meet.
Plates and BoundariesTwo types of crust:1. Oceanic crust2. Continental crust
Three types of boundaries:1. Collide2. Separate3. Slide past
Fault – Border of plate boundaries
Convergent Boundary
Plates collide3 types based on types of crust
colliding1. Continental-continental
◦Create mountains◦Examples
Warm-up
Put Impact List in red box
Which piece of evidence for plate tectonics do you think is most compelling and why? Compelling: strong and forceful, having
influence
You find an axe made of stone containing Uranium-235. You determine it has undergone 7 half lives. What percentage of U-235 is remaining and how old is the axe? (Half life of U-235 is 703.8 years)
Convergent Boundary2. Oceanic-oceanic
◦Older plate is subducted (more dense)◦Subduction forms trench◦Example
3. Continental-oceanic◦Oceanic is subducted◦Creates: Trenches Volcanoes
◦Example
Warm-up
What are the three different convergent boundaries? What does each one cause?
Based on the movements of the other types of boundaries (look back in your notes!) – what do you predict they cause?
Divergent BoundaryPlates separate
◦Space fills with magma◦Creates new crust◦Pushes old out
2 types
Divergent Boundary
1. Continental-Continental or on Continental Plate
◦ Creates rift valley May become lake Examples
Iceland
Divergent Boundary
2. Oceanic-Oceanic◦ Spreading center◦ Mid-ocean ridge◦ Majority of Earth’s volcanoes
Non-explosive
Transform BoundaryPlates slide past each other Not a smooth movementNo creation or destruction of crust
Earthquakes!
San Andres Fault
Hand-Signals…Show me:
1. Convergent boundaries = Collide
2. Divergent boundaries = Dividing
Check for understanding
What type of boundary is this?
Check for understandingIs the following picture:1. Convergent boundaries2. Divergent boundaries
Check for understandingIs the following picture:1. Convergent boundary2. Divergent boundary
Volcanoes!
Explosive EruptionsRare
◦Total number: DestructiveProduce
◦Debris◦Ash◦Gas
Pyroclastic Flow
Pyroclastic FlowsLarge amount of
material produced in small amounts of time
Temperatures greater than 700 deg. Celsius
Faster than a hurricane
Lahar
Deadly
Non-explosive Eruptions Most common
Produce◦Huge amounts of
lava◦Calm lava flows
Shape our world◦Islands in the
Pacific◦Sea floor
Create a modelCreate a model to help you learn
the different types of plate boundaries.
You will be adding one more type tomorrow.
Be sure to include each subtype of each of the two boundary types we talked about today.
Warm-up 11/101. How are convergent and divergent
boundaries similar? 2. Give a current example of a
convergent boundary and what is being formed there.
3. What type of plate boundary is seen here How do you know?
Hot Spots
PhenomenonTheories
◦Mantle plumes◦Cracks in crust
Far from boundary◦Examples
Appear to move over time
◦Why?
Warm-up 11/11-12What type of boundary creates mountains? Be specific.
Radiometric dating is _________ dating.Which layer of the Earth is responsible for the movement of tectonic plates?
The half-life of plutonium is 6530 years. A sample contains .39% of the original amount of plutonium. How many half-lifes have passed and how old it it?
EarthquakesWhat are they? What is it like?SeismologistWhere?
◦Plate boundary◦Occur at faults◦Varying depths◦Focus
Epicenter
How are earthquakes measured?
Richter scale◦ Strength
(magnitude)◦ Measuring ground
motion◦ Used by the media
Moment magnitude◦ More precise◦ Measures the
energy released◦ Measured at the
epicenter◦ Used by scientists
Largest Recorded Earthquakes
Recent earthquakes Tracker
Imaging of Earthquake Waves
Seismograph◦Measures and records local movement
◦3 main waves1. P wave2. S wave3. Surface
waves
Earthquake Waves
P waves◦ Primary◦ Fastest - First detected◦ Back-and-forth
S waves◦ Secondary◦ Side-to-side◦ Slower, arrive later
Surface◦Last to arrive◦Rolling◦Side-to-side◦Close to surface◦Slowest◦More destructive
Aftershocks
Foreshocks
Finding the EpicenterDistance vs. time
graph is constant◦Closest has
smallest time difference
Measure time difference on local seismograph◦Compare to graph◦Find distance
Repeat for multiple locations
Finding Epicenter continued…
Use distances found
Draw a circle from each site
Overlap = epicenter
Need at least 3 points
Warm-up1. Which type of plate boundary do you think has the greatest impact on society? Justify your answer.
2. If the P wave of an earthquake arrives at 10:45 am and the S wave arrives at 10:55 am, how far are you from the epicenter?
Earthquake Hazard Map
Earthquake PredictionNot exactSeismic gaps
◦Area of fewer earthquakes
◦Likely location of future earthquake
◦Used to predict 1989 San Francisco
Past frequency
Destruction from EarthquakesLiquefaction
◦ Mixing soil with underground water
◦ Sinkholes LandslidesFire
◦ Broken gas and electrical lines
◦ Lack water to fight
Building and highway damage
Hand-Signals…Show me:
1. Convergent boundaries = Collide
2. Divergent boundaries = Dividing
3. Transform boundaries = Slide
What type of boundary is this?
TsunamiHow?
◦Displacement of a large volume of water
◦CausesMassive waves
◦Wavelength◦Height◦Period
Impacts coastline◦Wave slows◦Increases in
height
Tsunami warning system
Only a few a yearMost recent (major)
◦Indonesia (Dec. 2004)
◦Japan (Mar. 2011)Seiche
Ring of Fire
To learn more about the dinosaur, I would find and observe the layers that the fossil was found in. This would help to find the relative age the fossil is and could find out the order of the geological events that happened in the layer like a fault or intrusion. With the little bones they found, they can use carbon-dating to find the absolute age and what time period it was in. Using its age, they could find out where the dinosaur lived because the continents used to be in different places during a certain time period, if the dinosaur was in that time period they could examine its jaw and teeth structure to find what it would eat. If they find what it eats, they could help determine where it lived; for example, if it ate plants they could narrow the location to where the climate could sustain plants. If it ate meat, they could find animals that lived in the same time period and animals that are prey to the size of this dinosaur and find other animals’ locations to narrow where this dinosaur lived. To find out more about this dinosaur they could use carbon-14
that was in the body to tell how old it is. They could look in the same rock layer that is was found to tell the climate of the area around the dinosaur. They may find fossils of plants or other animals near that area, then check its mouth for what type of teeth it has, that’s why the other fossils are needed so they could know what it ate – if it was an herbivore, carnivore, or omnivore.