Deck 6: The Active Earth: Plate Tectonics

Question 1

If a geologist was studying oceanic crust, the rock material he or she collected would be primarily composed of __________________.

A) granite
B) iron and nickel
C) shale
D) basalt

Answer 1

D

Question 2

The ____________________ theory states that the lithosphere is a shell of hard, strong rock that floats on the hot, plastic asthenosphere.

Answer 2

plate tectonics

Question 3

The Hawaiian Island chain was formed over a(n) ____________________.

Answer 3

hot spot

Question 4

If a geologist is studying volcanoes on the ocean floor, she or he is examining a _________________.

Question 5

____________ was found in the equatorial regions of Wegener's supercontinent called Pangea.

A) Glacial deposits
B) Fossil evidence
C) Coal
D) Similar rock material

Question 6

The Antarctic Circumpolar Current isolated Antarctica over the South Pole because of ___________ ___________ that occurred between 38 and 28 million years ago.

Question 7

The _______________ includes Earth's crust and the uppermost strong and rigid part of the mantle.

A) lithosphere
B) asthenosphere
C) atmosphere
D) biosphere

Question 8

In which part of the lithosphere would a geologist study convection which is the weak, plastic, and partly molten uppermost portion of the mantle?

Question 9

If a geologist studied the San Andreas Fault, she or he would be examining what specific type of plate boundary? ____________________

Question 10

Alfred Wegener theorized that Earth's continents were once joined together and later split, and drifted apart because of which of the following pieces of evidence?

A) Fossil evidence on Gondwanaland
B) Glacial evidence on Gondwanaland
C) Sandstone structures of ancient sand dunes found at 30° north and south latitudes
D) Coral reef fossils in the polar regions

Question 11

A geologist would expect this phenomena to occur when one plate slips past another. _____________

Question 12

Would pressure inhibit melting in the upper or lower mantle preventing rock from melting? __________________

Question 13

A geologist who studies two continental plates which are pulling apart is examining what specific type of divergent plate   boundary?

Question 14

In which part of the Earth's layers would a geologist expect to find predominantly peridotite which is a rock that is denser than the basalt and granite of the crust?

Question 15

There have been three supercontinents in geologic past. Which supercontinent would contain fossil evidence since it formed during the Paleozoic Era?    ____________________

Question 16

If a scientist discovers beaches that formed when glacier had depressed Scandinavia to sea level during the Last Ice Age, they would see that these beaches now lie well above that elevation because the land rose due to ___________.

Question 17

If a geologist was studying continental crust, the rock material she or he collected would be primarily composed of ___________________.

A) granite
B) iron and nickel
C) basalt
D) shale and limestone

Question 18

Geologist who studies the Pacific Northwest, Northern California, Oregon, and British Columbia are examining what specific type of plate boundary? ________________

Question 19

A geologist who studies the uppermost mantle and overlying crust would be researching which specific segment of the lithosphere? ________________

Question 20

Scientists theorize that tectonic plate movements formed the first ____________________ between 2 billion and 1.8 billion years ago.

Question 21

Where two plates carrying oceanic crust converge __________________.

A) they form a Mid-Oceanic Ridge
B) both plates stop moving
C) the older, denser plate sinks into the mantle
D) the crust collides to form a large mountain range

Question 22

Which layer of the Earth makes up 80% of Earth's volume? ___________________

A) Lithosphere
B) Mantle
C) Outer core
D) Inner Core

Question 23

If you were studying guyots in the Pacific Ocean, which would be the oldest of the chain?

A) The guyots that were close to mid-oceanic ridges
B) The guyots that were half-way from the mid-oceanic ridges to oceanic trenches
C) The guyots that were closest to oceanic trenches
D) None of the above

Question 24

If you were a geologist studying Harry Hess during World War II, which specific discovery would you have made after mapping the depth of the ocean floor? _________________

A) Magnetic stripes
B) Guyots
C) Subduction zones
D) None of the above

Question 25

The concept that suggests the asthenosphere flows laterally away from a region to make space for a heavy lithospheric mass is known as ___________________.

A) seafloor spreading
B) convergence
C) divergence
D) isostasy

Question 26

If you were a geologist, you would expect what to form inland near subduction zones due to the movement of mantle through the lithosphere.

A) Hot spots
B) Volcanoes
C) Mantle plumes
D) Rifts

Question 27

The seafloor and oceanic crust at the Mid-Atlantic Ridge becomes _________ with increasing distance from the ridge axis.

A) newer
B) thinner
C) older
D) more magnetic

Question 28

If you were a geologists studying the Himalayan Mountain Range, you would be examining what specific type of plate boundary?

A) convergent
B) divergent
C) transform
D) rift valley

Question 29

A ___________________ zone occurs when a less dense plate converges with a plate of higher density.

A) transform
B) rift
C) spreading
D) subduction

Question 30

Which of the following provided evidence for Wegener's theory?

A) differences in sea level heights
B) Earth's internal pressure changes
C) fossil records
D) magnetic polarity

Question 31

The circulation of the mantle is driven by which of the following?

A) heat from the upper lithosphere
B) cooling in the lower mantle
C) radioactive decay of unstable isotopes
D) reversal of magnetic polarity

Question 32

The downslope sliding of the lithosphere away from a spreading center is called a ____.

A) ridge push
B) slab pull
C) hot spot
D) mantle plume

Question 33

When a plate carrying continental crust converges with a plate carrying oceanic crust _________.

A) the oceanic plate floats above the continental plate
B) the continental plate sinks into the mantle
C) a divergent boundary forms
D) the oceanic plate sinks beneath the continental plate and dives into the mantle

Question 34

If you were a geologist studying the movement of tectonic plates, you expect a plate to typically move at rates of 1 to about 16 __________ per year.

A) millimeters
B) meters
C) centimeters
D) kilometers

Question 35

__________ have occurred on average every 500,000 years during the past 65 million years of Earth's history.

A) Supercontinents
B) Major mass extinctions
C) Banded iron formations
D) Magnetic reversals

Question 36

If you were a geologist, where on Earth would you search to find the oldest rocks?

A) seafloors
B) continents
C) spreading centers
D) ocean ridges

Question 37

When two continental plates converge, they form ____.

A) huge mountain ranges
B) a subduction zone
C) a transform boundary
D) a mantle plume

Question 38

If you were a geologists studying the Mid-Atlantic Ridge, you would be examining what specific type of plate boundary?

A) Convergent
B) Divergent
C) Transform
D) None of the above

Question 39

The entire mantle-lithosphere system circulates in great ______________ cells.

A) Spreading
B) Reversal
C) Plume
D) Convection

Question 40

Earth's outer core is _________________.

A) cool and brittle
B) composed of helium
C) molten due to relatively lower pressure
D) as hot as the surface of the Sun

Question 41

Since the temperature of the inner core is 7000°C, it is hot enough to make the rock material molten in spite of the pressure that sits on top of the inner core.

Question 42

According to the supercontinent model, ____.

A) at some future time, all continents will join together in a single supercontinent, and tectonic activity will cease
B) continental fragments have migrated around the globe and reassembled as a supercontinent at least three times in Earth's history
C) the breakup of a future supercontinent will lead to the destruction of all continental crust in subduction zones
D) all the geologic areas within a supercontinent have the same radiometric age

Question 43

A single plate can carry both oceanic and continental crust because both types of plates comprise the lithosphere.

Question 44

The weight of an ice sheet can cause continental lithosphere to sink due to ____.

A) convergence
B) isostatic adjustment
C) divergence
D) transformation

Question 45

What is a possible explanation for why the chemical composition of basalts from mid-oceanic ridges is different than those that erupt at hot spots?

A) subduction zone model
B) single-layered mantle model
C) spreading center model
D) two-layered mantle model

Question 46

Lithosphere is thickest at oceanic spreading centers because the ocean lithosphere crumple against each other causing a huge mountain range to form.

Question 47

The internal heat from Earth's early melting event and from the continued decay of radioactive isotopes has allowed the interior of the Earth to remain hot even though the surface has cooled off.

Question 48

Some scientists suggest that future plate motions will rearrange the current configuration of continents, and form the next supercontinent near the present-day ____.

A) North Pole
B) Equator
C) South Pole
D) Australia

Question 49

The interior of lithospheric plates are normally tectonically active with occurrences of earthquakes and volcanoes because these areas represent major plate boundaries.

Question 50

Continental rifting occurs when two continental plates pulling apart because basaltic magma works it way through the granitic crust allowing for volcanoes to erupt both basaltic and rhyolitic compositions.

Question 51

The lithosphere floats on the asthenosphere because it is made of continental and oceanic crust that is buoyant rock and of the upper mantle where the temperature is cool and its pressure is low.

Question 52

Continental crust does not normally sink into the mantle because continental crust is of lower density than mantle material as compared to oceanic crust that is high in iron and nickel.

Question 53

The scientific community embraced Wegener's supercontinent theory because he was able to prove how continents drifted in geologic past.

Question 54

Oceanic crust subduction into the mantle is the reason Manhattan Island is now nine meters farther from London than it was in 1776.

Question 55

The Mid-Oceanic Ridge is elevated above surrounding seafloor because it is made of hotter and less dense lithosphere than oceanic crust farther away from the divergent boundary.

Question 56

Oceanic crust is thicker than continental crust because it is composed of granite.

Question 57

If you were a geologist looking to identify the source of volcanic magma, you would search for evidence of a what? ______________

A) area in the upper mantle where hot magma forms a volcanic center
B) divergent boundary between two plates
C) spreading center where new crust is formed
D) rising column of hot, plastic mantle rock called a mantle plume

Question 58

The reason that the mantle below the asthenosphere is stronger than the mantle above it is because the increasing pressure overcomes the effect of rising temperature.

Question 59

The asthenosphere is deep enough below Earth's surface that the weight of glaciers and mountains can cause the asthenosphere to move laterally away from the depressed region,

Question 60

The seafloor spreading hypothesis was put forth after oceanographers detected changes in the magnetic polarity of newly formed oceanic crust near the Mid-Atlantic Ridge.

Question 61

Explain the two possible mechanisms that Wegener proposed to explain how continents drift.

Question 62

Explain why the mantle contains plastic and weak rock in the asthenosphere yet stronger rock at the bottom of the mantle near the outer core.

Question 63

Explain why volcanoes are not common at transform plate boundaries.

Question 64

Explain why convection is more rapid in shallow parts of the mantle as compared to deep parts of the mantle.

Question 65

Explain how a subduction zone is impacted by a mid-oceanic ridge (MOR).

Question 66

Explain how mantle convection drives continental drift.

Question 67

Explain why there are matching magnetic stripes on either side of a mid-oceanic ridge.

Question 68

Explain why mantle rock becomes weak and plastic in the asthenosphere.

Question 69

Explain why the inner core is not molten even though it is 7000°C.

Question 70

Explain how new ocean basis are formed on Earth.

Question 71

Explain how a hot-spot forms and how they differ from mantle plumes.

Question 72

Explain how the work of Vine, Matthews, and Morely supported Harry Hess's hypothesis of sea floor spreading.

Question 73

Explain why the fossil evidence that Wegener compiled supported his theory of continental drift.

Question 74

Explain why the rock evidence that Wegener compiled supported his theory of continental drift.

Question 75

Explain why the age of continental crust is older than oceanic crust.

Question 76

Explain how pressure makes it difficult for a rock to melt.

Question 77

Explain why two converging continental plates produces the thickest crust on Earth.

Question 78

Explain why the ocean crust contains magnetic stripes.

Question 79

Explain why the chemistry of oceanic plates cause them to sink beneath continent plates at subduction zones.

Question 80

Explain how rift zones impact supercontinents like Pangea.