Oceanography ch. 2

Which of the following statements about tectonic plates is true?

Most tectonic plates contain both oceanic and continental lithosphere

What is the relationship between continent edges and plate boundaries?

Very few plate boundaries follow the edges of continents

What was Panthalasse

the single ocean that existed after the Pangaen super continent formed

What was the Tethys Sea?

a piece of the Panthalassa Ocean that existed after the Pangaean super continent formed

What was Pangaea

A supercontinent that began to break apart about 200 million years ago

what were the names of the two smaller super continents that formed when Pangaea broke apart?

Laurasia and Gondwanaland

Which supercontinent contained Africa and South America

Gondawanaland

What caused the formation of the Himalayas?

The collisions of India with Asia

Which type of plate boundary is most closely associated with the formation of new ocean floor?

divergent

Which of the following statements about Earth’s magnetic field is most accurate?

Earth’s magnetic field switches polarity at irregular time intervals

How often does the Earth’s magnetic field switch polarity?

every 100,000 to several million years

How are normal polarity and reverse polarity of earth’s magnetic field different?

A compass points toward the North Pole during normal polarity and to the South Pole during reverse polarity

in general, what is our best evidence that the orientation of Earth’s magnetic field has changed over time?

A record of Earth’s magnetic field is recorded in oceanic rocks, which show a clear pattern of changes in Earth’s magnetic polarity

Where would you expect to see alternating bands of rock with different magnetic polarities

on both sides of the mid-ocean ridge

What is the relationship between the crust and lithosphere?

The crust is part of the lithosphere

Complete this statement: Divergence is to moving away as convergence is to ____

moving toward

Platers move apart at ____ boundaries, move together at ____ boundaries, and move side-by-side at _____ boundaries

divergent/convergent/transform

Which geologic features are associated with divergent boundaries

mid-ocean ridges and continental rift valleys

Which geologic features are associated with convergent boundaries?

Ocean trenches and volcanoes

Where is the youngest ocean floor found?

along the crest of mid-ocean ridges

What would happen to Earth if ocean floor were created at divergent boundaries at a faster rate than it is destroyed at convergent boundaries?

The Earth would increase in volume

What is a volcanic arc?

A row of volcanoes that forms on the overriding plate near a subduction zone

Which of the following mountain ranges are examples of continental arcs?

Andes and Cascades

When will magma rise to Earth’s surface?

When the magma is less dense than adjacent rock

In general, when will melted rock in the mantle rise?

almost always

How are felsic magmas formed?

Hear from the mantle melts part of the lower crust

In general, why does Earth’s crust sit on top of the mantle?

Earth’s crust is less dense than the mantle

How do mafic volcanic rocks get to Earth’s surface?

Pressure from overlying crust forces mantle magmas through cracks to Earth’s surface. These magmas erupt out of volcanoes, cool, and solidify into rock

Which mountain belt lies to the north of India?

The Himalayas

In general what are the Himalayan mountains composed of?

folded and faulted rock

Which of the following statements is most accurate?
countries

A moving India collided with a stationary Asia about 30 million years ago

Which of the following statements is most accurate?
landmass

Prior to 30 million years ago, Tibet was a much thinner landmass than it is today

Which type of plate boundary exists between India and Asia today?

a convergent boundary

Why didn’t india subduct under Asia

the two continents have similar densities

Did any subduction occur during the collision of india and Asia?

Yes; ocean basic between these two continents subducted under Asia

What is the relationship between the crust and the lithosphere?

The crust is part of the lithosphere

Complete this statement: Divergence is to moving away as convergence is to

moving toward

What are rocks below and above a fault called

the football below and the hanging wall above

which type of force is repsonsible for nomal fault formation

tensional force

which type of force is responsible for reverse fault formation

compressional force

which type of force is responsible for normal strike-slip formation

shear force

which type of fault has no vertical motion of rocks associated with it

strike-slip fault

What is the relationship between the crust and the lithosphere

All of the crust is contained within a larger layer called the lithosphere

What is the relationship between the mantle and the lithosphere?

some of the mantle is contained within a smaller layer called the lithosphere

What is the relationship between the mantle and the asthenosphere

All of the asthenosphere is contained within a larger layer called the mantle

What surface feature provides evidence for the location of hot sports?

volcanoes within tectonic plates

When will a hot spot volcano become extinct

when the volcano is carried away from the hot spot by the tectonic plate

What surface feature would you expect to form if both a hot spot and a tectonic plate are stationary

a single volcano

What is a seamount?

An active volcano that occurs along the crest of the mid-ocean ridge

What is a tablemount?

A seamount that grew above sea level, experienced wave erosion, and is now inactive

Where do coral reefs exist with sea mounts

in tropical latitudes

Which of the following statements about coral reefs and seamounts is most accurate

Coral reefs at the ocean surface grow away from seamounts over time

Why do coral reefs at the ocean surface grow away from seamounts over time?

Seamounts subside as tectonic plates move. Coral reefs grow away from the seamount in order to stay near the sunlight

What is the difference between a barrier reef and an atoll?

Barrier reeds surround an inactive volcano emerging above sea level, while atolls surround the previous location of a submerged volcano

Which is the correct order of coral reef development near seamounts

Fringing reef, barrier reef, atoll

Which hypothesis best explains the continuous bend in the Hawaiian Islands-Emperor Seamount chain?

the direction of plate motion shifted over time over a stationary mantle plume (hot spot)

Sea floor spreading along the axis of an oceanic ridge results in symmertical patterns of all the following except

the location of subduction zones

The following set of observation describes an actual body of water. Evaluate these statements and determine the evolutionary stage of ocean basin based upon the following characteristics

a. lacks a mid-ocean ridge b. deep ocean basin is present c. early signs of mountain formation d. volcanic island arc and trench absent -terminal

Earthquakes can occur only in the

Lithosphere

Iceland is located on what type of plate boundary

Divergent

Loihi is

the newest Hawaiian volcano

The cities of Los Angeles and San Francisco, CA, are about 380 miles apart. Plate motion along the San Andreas Fault is about five centimeters per year. If the Los Angeles Dodgers and the San Francisco Giants continue to play at their current locations, how long will it be before their games will constitute a cross-town rivalry?

about 12,230,000

A researcher interested in the vertical zonation of oceanic lithosphere would want to study

ophiolites

Which of the following is the main reason that Earth has a magnetic field?

Convection in the liquid iron-nickel outercore generates a magnetic field

Of the following statements about Earth’s magnetic field, which are true

– The locations of Earth’s magnetic poles have moved through time and have even reversed in polarity. – The magnetic field is oriented horizontal (parallel) to Earth’s surface at the magnetic equator. – The magnetic field is oriented vertical relative to Earth’s surface at the north magnetic pole. – Earth’s magnetic field has varying dips around the world that range from vertical to horizontal, depending on latitude. – The magnetic field is oriented vertical relative to Earth’s surface at the south magnetic pole.

Of the following statements about ocean crust which are true?

Ocean crust is created at the mid-ocean ridge

What do all plate boundaries have in common

They are all associated with zones of earthquakes

Of the following statements about nemataths and volcanic arcs which are true

– Nemataths and volcanic arcs are both the result of volcanic activity. – A volcanic arc is associated with a convergent plate boundary. – A nematath is created by a hotspot. – In a nematath, the age of the volcanoes progressively decreases as you move closer to the volcanic source. – In a volcanic arc, any of the volcanoes can be active at any time.

Match the term with the appropriate phrase: supercontinent 250 million years ago

Pangaea

Match the term with the appropriate phrase: study of magnetism over geologic time

paleomagnetism

Match the term with the appropriate phrase: island arc

subduction zone

Match the term with the appropriate phrase: seafloor magnetic stripes

spreading center

Match the term with the appropriate phrase: trench

subduction zone

The magnetic north pole has remained very close to the geographic North Pole throughout all of geologic time

false

New crust is formed at trenches and older crust is subducted at oceanic ridges

false

The magnetic field of the Earth reverses itself each time that magma erupts at a mid-ocean ridge

False

New crust is formed at trenches and older rust is subducted at oceanic ridges

False

The magnetic north pole has remained very close to the geographic North Pole throughout all of the geologic time

False

Deep-sea trenches are found at convergent plate

true

water depth decreases as you move away from the mid-ocean ridge

false

Convergent plate boundaries occur when tectonic plates move away from each other

False

Areas of intense volcanic activity that remain in more or less the same location over long periods of geologic time and are unrelated to plate boundaries are called hotspots

True

The majority of the wold’s hotspots are associated with plate boundaries

False

Charles Darwin was the first person to propose a hypothesis on the origin of coral reefs

True

The Wilson Cycle uses plate tectonic processes to show the life cycles of ocean basins during their growth, formation, and destruction over geologic time

True

Evidence for continental drift includes

All of the above

Fossils of ancient tropical plants are currently found near the poles because the

Plants lives in the tropics, but landmasses have drifted to current locations

Climate distribution on Earth is primarily controlled by

Lattitude

The book The History of Ocean Basins, which contained the idea of seafloor spreading, was written by geologist

Harry Hess

The seafloor magnetic pattern is best described as

Parallel to and symmetric about mid-ocean ridges

Tectonic plates are pieces of the ____ that float on the more fluid ____ below

a. Lithosphere b. Asthenosphere

The Mid-Atlantic ridge is an example of a

divergent plate boundary

Which of the following is characteristic of oceanic-continental convergent plate boundaries?

andesitic volcanoes

Which of the following is characteristic of continental-continental convergent plate boundaries?

uplifted mountain ranges

The hawaiian Islands are located where the Pacific plate is

Moving over a hot spot of mantle plume

Volcanoes on the seafloor that are flat-topped because of wave erosion are called

tablemounts

The first scientist to propose the origin of coral reefs based upon subsidence (sinking) of volcanic islands was

Charles Darwin

The study of historical changes of continental shapes and positions is called

paleogeography