Mrs. Lafrate's Class



Plate Tectonics Webquest KEY

In this webquest, you will be directed to a specific website or you will need to search on your own to answer the questions. List all websites that you obtain information from (that have not been given to you) and attach that list to this webquest. Do not use websites such as or Wikipedia to locate information.

TASK #1- Go to

Locate the following plate boundaries in North America and describe in detail their location, which plates are involved and what land features they created.

CONVERGENT PLATE BOUNDARY- Ancient Convergent Plate Boundary - Appalachian Mountain Range   formed by the ancient continental boundaries of North America and Africa colliding.

TRANSFORM PLATE BOUNDARY-Transform Boundary - San Andreas Fault Zone

The linear features are faults formed in the fracture zone between the Pacific and North American plates

DIVERGENT PLATE BOUNDARY-) Divergent Boundary - Mid-Atlantic Ridge

Fissure marking the position of the Mid-Atlantic Ridge - lateral offsets in the Ridge caused by transform faults (Eurasian plate moving away from the North American Plate. Iceland is splitting along the ridge's center.)

Locate at least one of the following plate boundaries on the map located in other parts of the world. Describe in detail their location and what land features they created. Additional points given for locating and describing more than one. (use separate sheet of paper if necessary)

CONVERGENT PLATE BOUNDARY- (1) convergent Boundary - Kuril Islands - Between Kamchatka and JapanThe Kuril Islands are part of a volcanic island chain produced by the subduction of the Pacific Plate beneath the North American Plate (2) Convergent Boundary - Aleutian Islands Volcanic islands along the boundary between the North American and Pacific Plates  (3) Convergent Boundary - Andes Mountain Range Volcanic activity atop of the South American Plate, a few hundred miles east of its collision with the Nazca Plate (4) Convergent Boundary - India and Asia - Himalaya Range Continents collide as India plows into Asia. The Indian Plain suddenly rises to the peaks of the Himalaya Mountain Range (5) Convergent Boundary - Caribbean Volcanic Arc Volcanic islands on eastern margin of the Caribbean Plate in contact with the South American Plate. (6) Convergent Boundary - Cascades Volcanoes

A north-south trending line of volcanoes atop of the North American Plate, slightly inland from its boundary with the Juan de Fuca Plate - 

TRANSFORM PLATE BOUNDARY- (1) Transform Boundary - Alpine Fault, South Island, New Zealand

The Alpine Fault is a strike slip fault between the Australian Plate and the Pacific Plate. 

DIVERGENT PLATE BOUNDARY- (1) Divergent Boundary - Mid-Atlantic Ridge

Fissure marking the position of the Mid-Atlantic Ridge - lateral offsets in the Ridge caused by transform faults (Eurasian plate moving away from the North American Plate. Iceland is splitting along the ridge's center.) (1) Divergent Boundary - Red Sea A narrow sea formed where the African and Arabian Plates are diverging

(2) Divergent Boundary - East Africa - Volcanoes and Lakes Volcanoes and linear lakes within the rift valley of a developing divergent boundary in East Africa In East Africa, spreading processes have already torn Saudi Arabia away from the rest of the African continent, forming the Red Sea. The actively splitting plates are the African Plate and the Arabian Plate  forming the East African Rift Valley

TASK #2 MOVING AND GROOVING PLATES



TASK #3- Go to

Click Historical Perspective

1- Define plate- a plate is a large, rigid slab of solid rock

2- What is the origin of the word tectonics? The word tectonics comes from the Greek root "to build."

3- According to the continental drift theory, when did Pangaea begin to break apart? 225-200 million years ago

4- What is the origin of the word Pangaea?  "all lands" in Greek

5- What two supercontinents were formed from Pangaea in the Triassic period? Gondwanaland and Laurasia

6- What three pieces of evidence did Wegener have to prove his theory? the occurrences of unusual geologic structures and of plant and animal fossils found on the matching coastlines of South America and Africa, which are now widely separated by the Atlantic Ocean, as well as the evidence of dramatic climate changes on some continents.

7-What was Wegener's most compelling evidence to prove his theory?  the presence of identical fossil species along the coastal parts of Africa and South America was the most compelling evidence that the two continents were once joined.

8- Click “rejoined continents” and provide one detailed example of this evidence.

[pic]

Return to Historical perspective.

9 How and when did Alfred Wegener die?  He froze to death in 1930 during an expedition crossing the Greenland ice cap

10- What was the fundamental question raised by his critics that Wegener could not answer?

What kind of forces could be strong enough to move such large masses of solid rock over such great distances?

Go to “developing the theory”

11- Name the four major scientific developments that contributed to the formation of the plate-tectonics theory.

1) demonstration of the ruggedness and youth of the ocean floor; (2) confirmation of repeated reversals of the Earth magnetic field in the geologic past; (3) emergence of the seafloor-spreading hypothesis and associated recycling of oceanic crust; and (4) precise documentation that the world's earthquake and volcanic activity is concentrated along oceanic trenches and submarine mountain ranges.

12- What do we call scientists who study Earth's ancient magnetic field? Paleomagnetists

13-What is the magnetic mineral found in rocks on the ocean floor? magnetite

14- Explain in your own words, the difference between normal and reversed polarity?

Normal polarity occurs when the  polarity alignment is the same as the Earth's present day magnetic field, therefore the north end of the rock's "compass needle" points toward magnetic north. Reversed polarity occurs when the polarity alignment is opposite to that of the Earth's present magnetic field. In this case, the north end of the rock's compass needle would point south.

15- What process built the mid-ocean ridge system? Sea floor spreading

16- Who first coined the term sea floor spreading? Hess and Dietz

17 -Explain how can new crust be continuously added along the oceanic ridges without increasing the size of the Earth? The older crust is recycled at convergent plate boundaries. The older oceanic crust eventually descends into the oceanic trenches  or subducts under continental crust

18- Name the four types of plate boundaries and explain how they interact with each other.

Divergent boundaries -- where new crust is generated as the plates pull away from each other.

Convergent boundaries -- where crust is destroyed as one plate dives under another.

Transform boundaries -- where crust is neither produced nor destroyed as the plates slide horizontally past each other.

Plate boundary zones -- broad belts in which boundaries are not well defined and the effects of plate interaction are unclear.

19- Which divergent plate boundary is the most well known? Mid-Atlantic Ridge

20- What is the rate of spreading at this plate boundary? 2.5 cm/yr

21- Which country straddles this plate boundary? Iceland

22- What was created by the breaking off of Saudi Arabia from the rest of the African continent? The Red Sea

23- Along what type of plate boundary does destruction of the crust take place?

Convergent plate boundaries

24- Name 2 features created by an oceanic-continental convergent plate boundary. Trenches and volcanoes (volcanic arcs)

25-Name 2 features created by an oceanic-oceanic convergent plate boundary. Oceanic trenches and island arcs

26- Name the 2 features created by continental-continental convergent plate boundary. Mountains and plateaus

27- Where are most transform fault boundaries found? In the ocean

28- What is the name of the transform boundary that cuts through 2/3 of the length of California?

The San Andreas Fault

29- Which two plates are grinding against each other at this boundary? The North American Plate and the Pacific Plate

30- What is the rate of plate movement at this boundary? 5 cm/yr

31- In what direction is the land on the west side of the fault moving? North west

Click “Hot spots”

32- True or False- Hot spots are located on plate boundaries. False

33- What are hot spots? A hot spot is an area of persistent volcanic activity

34- How did hot spots form the Hawaiian Islands?  The magma, which is lighter than the surrounding solid rock, then rises through the mantle and crust to erupt onto the seafloor, forming an active seamount. Over time, countless eruptions cause the seamount to grow until it finally emerges above sea level to form an island volcano. Continuing plate movement eventually carries the island beyond the hotspot, cutting it off from the magma source, and volcanism ceases. As one island volcano becomes extinct, another develops over the hotspot, and the cycle is repeated.

Click unanswered questions

35- What sources provide heat within the Earth? radioactive decay and residual heat

36- What three mechanisms help to explain plate tectonic movement on Earth?

Mantle convection, ridge push, and slab pull

37- In your own words, explain how each mechanism works.

Mantle convection- As mantle material is heated, it rises and cooler mantle material sinks. Plates ride along this convection motion

Ridge Push- The new ocean floor at a mid ocean ridge “pushes” the older ocean plate away

Slab pull -  sinking of a cold, denser oceanic slab into the subduction zone (called "slab pull") -- dragging the rest of the plate along with it -

TASK #4

Take the online quiz and circle your answers below. (10 points)

1) Which type of plate is older?

Continental  Oceanic

2. Which type of plate is thicker?

Continental  Oceanic

3. What is it called when two oceanic plates move apart and new crust is formed?

Crustal integrating  Seafloor spreading

4. What is it called when one plate is pushed under another plate as they collide?

Subduction   Mantle induction

5. What is one phenomenon that can happen when two plates slip past one another?

  Earthquakes   Subduction

6. What can form when two continental plates collide?

Fold mountains  Volcanoes

7. What do plates float on?

Corona  Upper mantle

8. New crust is created by _____?

Magma from the mantle  Magma from the core

9. What is the name of the supercontinent that formed from about 200 to 100 million years ago?

Pangaea  Laurasia

10. Who first proposed the theory of continental drift?

Galileo  Wegener

TASK #5 (10 points; 5 extra credit)

Use the link above to create a crossword puzzle. You must use 20 word and provide hints for each word. Print 2 copies of your completed puzzle. Create an answer key on one copy and attach both copies to this webquest.

Print a 3rd copy and give to a classmate to complete for an extra 5 points

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