Lesson 15 Plate Tectonics

Question 1

What was the main objection to Wegener’s proposal?

Answer 1

its inability to provide a mechanism for the movement of continents

Question 2

When did Alfred Wegener first proposed his hypothesis?

Answer 2

1915

Question 3

What did Afred Wegener publish with his hypothesis ?

Answer 3

The Origin of Continents and Oceans

Question 4

Who discovered ideas about continental drift: an idea before its time?

Answer 4

Afred Wegener

Question 5

Wegener’s continental drift hypothesis said that a super continent called _______ began breaking apart into smaller pieces how many years ago?

Answer 5

Pangaea

200 million

Question 6

What was Pangaea considered?

Answer 6

super-continent

Question 7

The smaller continental fragments that broke off then “drifted” to their _______. Continents “broke” through the ______

Answer 7

present positions

ocean crust

Question 8

What evidence did wegener use to support the idea that continents were once joined?

Answer 8

Fit of South America and Africa
Fossils match across the seas
Rock types and structures match
Ancient climates

Question 9

The theory of plate tectonics is a far more _______ theory than continental drift?

Answer 9

encompassing

Question 10

What occurs along the dynamic margins of these plates?

Answer 10

Most of Earth’s seismic activity, volcanism, and mountain building

Question 11

What is Earth’s rigid outer shell?

Answer 11

lithosphere

Question 12

What does the plate tectonics theory say the lithosphere contains?

Answer 12

7 plates

Question 13

What is the movement of the lithosphere plates?

Answer 13

moving slowly and relative to each other

Question 14

Where are most of the lithosphere plates found?

Answer 14

beneath the ocean

Question 15

What is the largest lithosphere plate?

Answer 15

Pacific plate

Question 16

What allows for the motion of he lithosphere?

Answer 16

Asthenosphere

Question 17

What is the temp and strength of the asthenosphere compared to the lithosphere?

Answer 17

Hotter and weaker than lithosphere

Question 18

Where does the asthenosphere exist?

Answer 18

beneath the lithosphere

Question 19

A major departure of the plate tectonics theory from the continental drift hypothesis is that large plates contain both __________ and the entire plate moves.

Answer 19

continental and ocean crust

Question 20

Where do all major interactions among plates occur?

Answer 20

along their boundaries

Question 21

In continental drift, Wegener proposed that the _______ continents “drifted” by breaking through the oceanic crust, much like ice breakers cut through ice.

Answer 21

sturdier

Question 22

What are the types of plate boundaries?

Answer 22

divergent
convergent
transform fault

Question 23

What boundary happens when two plates move apart?

Answer 23

Divergent plate boundaries

Question 24

When divergent plat boundaries form, what upwells to create what?

Answer 24

mantle upwells creating a new seafloor

Question 25

Where do divergent boundaries occur?

Answer 25

along the axis of the oceanic ridges

Question 26

What are divergent boundaries associated with?

Answer 26

seafloor spreading

Question 27

Where do continental rifts form?

Answer 27

spreading centers within a continent

Question 28

New divergent boundaries may form within a continent. Give example?

Answer 28

the East African Rift Valleys

Question 29

What is the normal spreading rate of the seafloor?

Answer 29

5 to 9 cm per year

2 to 15 cm per year

Question 30

What does divergent plate boundaries have?

Answer 30

constructive margins

Question 31

Where do oceanic ridges develop?

Answer 31

well-developed boundaries

Question 32

How much of the earths surface do oceanic ridges represent?

Answer 32

20 percent

Question 33

What may develop along the axis of oceanic ridges?

Answer 33

Rift valleys

Question 34

What are controlled by spreading rates of the seafloor?

Answer 34

Topographic differences

Question 35

What were plate tectonics considered?

Answer 35

the new paradigm

Question 36

When new divergent boundaries form within a continent, they fragment a ______ and develop a new ________

Answer 36

landmass

ocean basin