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Review for Plate Tectonics Test

This is the first part of your review.  The second part is another triangulation activity.  You will have one of those on your test, so make sure you’re comfortable with the process.

1.     What gases did volcanoes contribute to Earth’s early atmosphere?

 

Water vapor, carbon dioxide and nitrogen

2.     What causes the movement of plates and where is it happening?

 

Convection currents in the asthenosphere cause the movements of the plates.

3.     How does the age of the ocean floor change as you get closer to the mid ocean ridge?

 

The closer you get to the mid ocean ridge the younger the crust gets (new crust is made at the ridge).

4.     Where is the oldest oceanic crust located?

The oldest oceanic crust is located near the coastlines of continents (far away from the mid ocean ridge).

5.     Where do we find most active volcanoes?

Active volcanoes are usually found at plate boundaries (specifically boundaries that are experiencing subduction).

6.     How do oceanic crust and continental crust compare in terms of thickness and density?

 

Oceanic crust is thinner and more dense that oceanic crust.

7.     Draw diagrams to illustrate the direction of crustal movement at a transform boundary, a divergent boundary and a convergent boundary.

 


Transform boundaries

 

Divergent boundaries

 

Convergent boundaries 

 

8.     Rank the following seismic waves in order of increasing speed:  S waves, P waves and L waves

 

L waves, S waves and P waves

9.     Which type of seismic wave can travel through liquids?

 

P-waves can travel through liquids.

10. Which station had the latest arrival of P waves?  of S waves?  Which station had the earliest arrival of P waves?

 

Station B had the latest arrival of both P and S waves.

Station A had the earliest arrival of both P and S waves.

 

11. Sticky, thicker lava has a lot of  ______Silica_______________.  Thin, runny lava

 


that is characteristic of sheild volcanoes results in a rock called ____basalt___________.

12. Violent eruptions, steep sides that have alternating layers are characteristic of what kind of volcano?

Composite volcano (aka stratovolcano)

13. Describe in words what is happening at a transform boundary.

At a transform boundary two plates are grinding past each other.

14. Describe in words what is happening at a divergent boundary.

At a divergent boundary two plates are moving away from each other as new crust is formed.

15. Where is Earth’s magnetic field generated?

The Earth’s magnetic field is generate in Earth’s core.

16. Where do scientists find a record of the location of Earth’s magnetic poles?

The location of Earth’s magnetic poles is recorded in the alignment of certain minerals in igneous rock.  They “line up” with the magnetic field as they solidify.

17. What happens at convergent boundaries?  Be specific, there are a couple different things.

At convergent boundaries two plates collide into each other.  If the two plates are both made of continental crust, huge mountains are built.  If one or both of the plates is made of oceanic crust, subduction will happen and a deep ocean trench and volcanoes will probably result.

18. According to the following diagram what direction is the Pacific Plate moving?

The Pacific Plate is moving to the northwest over the hotspot that has created the Hawaiian islands.

19. Which type of seismic wave travels the slowest and causes the most damage?

L waves (aka surface waves) are the slowest and cause the most damage.

20. Describe the Earth’s asthenosphere.

Earth’s asthenosphere consists of the lower mantle.  It is plasticlike and has convection currents in it that are responsible for the movement of plates.

21. Describe the shape of a shield volcano.

Sheild volcanoes have large bases and shallow slopes.  They are made from runny lava and are the largest of type of volcano.

22. Describe the shape of a composite (strato) volcano.

Composite volcanoes have very steep slopes.  They are made from alternating layers of pyroclastic debris and rock made from thick viscous lava.

23. What do we call the point where the first movement of rock occurs in an earthquake?

The focus is the point where the first movement of rock occurs in an earthquake.

24. What type of volcano produces large pyroclastic flows?

Composite volcanoes produce large pyroclastic flows.

25. What is a pyroclastic flow?

A pyroclastic flow is a cloud of hot ash, toxic gases and rocky debris that is produced by the explosive eruption of a volcano.

26. List three hazards associated with volcanoes.

Lava flow, pyroclastic flow, lahars, poisonous gases (there are others too)

27. List three things volcanologists monitor to determine if a volcano is “gettng ready” to erupt.

·       seismic activity

·       the size and shape of the volcano (looking for a bulge resulting from moving lava)

·       changes in the gases being released.

28. Use the graph of p-wave and s-wave travel times to answer this question.  If an earthquake happens 1000 kilometers away from Piedmont, how long will it take before the first P-wave arrives?  How about the first S-wave?

It will take about 2 minute and 20 seconds for the P wave and about 4 minutes for the S wave to arrive.