Geology Chapter 2

In the mid-twentieth century, researchers dredging the seafloor could not find any materials older than ________.

180 million years

A typical rate of seafloor spreading in the Atlantic Ocean is ________

2 centimeters per year

Using the figure above, when was the last time the Earth had a magnetic reversal?

700,000 years ago

Which scientist developed the idea of continental drift?

Alfred Wegener

Crustal rifting is currently occurring in East Africa. Which of the following features would you expect to find there?

All of the above are correct

______ is a feature of a divergent plate boundary. CHOOSE ALL THAT APPLY. An oceanic ridge A rift valley A deep-ocean trench A continental volcanic arc A subduction zone

An oceanic ridge A rift valley

What is a mantle plume?

An upwelling of hot material from the Earth's interior that is cylindrical in shape

Which of the following is a layer of the Earth that is classified NOT by composition, but by physical properties?

Asthenosphere

respective bins. Would be found at a divergent boundary and Would NOT be found at a divergent boundary Options: Normal faults Volcanoes producing mafic lavas Thrust faults Volcanoes producing andesitic lava

Can - Normal faults Volcanoes producing mafic lavas NOT- Thrust faults Volcanoes producing andesitic lava

What is slab pull?

Cold oceanic lithosphere is pulled below warmer asthenosphere.

In a collision between two continental plates, can a continental plate subduct? Why or why not?

Continental plates are too buoyant to subduct.

Which of the following statements best describes Wegener's idea of continental drift?

Continents were formerly in different positions on the Earth and have shifted to their present locations over time.

Which type of tectonic boundary is the result of two tectonic plates colliding with each other?

Convergent boundary

Match the tectonic boundary with the type of stress affecting it. Convergent boundary− Compression −−Compression −− Tension −− Shear

Convergent boundary Divergent boundary Transform boundary

Which part of the Earth is responsible for generating the planet's magnetic field?

Core

What generates the heat necessary for convection in the Earth?

Decay of radioactive materials

Which tectonic boundary results when two tectonic plates pull apart from each other?

Divergent boundaries

Which of the following statements about earthquakes with magnitude greater than 4.0 is most accurate?

Earthquakes with magnitude greater than 4.0 occur in a pattern than correlates closely with plate boundaries.

Continental rifting is occurring today in ________.

Ethiopia and Kenya (East African Rift valley)

How was the fossil record of ancient life used to support Wegener's hypothesis about Pangaea?

Fossils of identical organisms were found on several continents, indicating the continents were once joined

________ and ________ drive water from the pores of a subducted oceanic plate, which leads to partial melting.

Heat; pressure

How is information about magnetic fields recorded in rocks?

Iron particles in magnetically susceptible minerals within basaltic lava align with the magnetic field of the Earth while the lava is still liquid and then freeze in position when the lava solidifies.

How is the thickness of the lithosphere going to change as it moves away from a divergent plate boundary?

Lithosphere will thicken as more mantle is added.

In which layer of the Earth does the convection necessary for plate motion occur?

Mantle

Which of the following statements explains why the presence of Mesosaurus in both South America and Africa supports the continental drift hypothesis?

Mesosaurus was a freshwater aquatic reptile with fossil remains in both South America and Africa.

What direction has the Pacific plate been moving for the last 40 million years?

Northwest

Part B - Transform boundaries in rift zones Drag the appropriate labels to their respective targets. Labels may be used more than once. Occurs at transform boundary and Does not occur at transform boundary Options: Deformation associated with shear stress Deformation associated with tensional stress Deformation associated with Compressional

Occurs - Deformation associated with shear stress DOES NOT OCCUR - Deformation associated with tensional stress and compressional. Question #43 Part B

What is the main material being subducted at an ocean-continent convergent boundary?

Oceanic lithosphere

Which type of convergence will result in a continental volcanic arc?

Oceanic-continental

Match the convergent boundary with a real-world example −− North American and Juan de Fuca plates −− Pacific and Philippine plates −− Indian and Eurasian plates

Oceanic-continental Oceanic-oceanic Continental-continental

Which type of convergence will result in a volcanic island arc?

Oceanic-oceanic

Using the map provided, locate three lithospheric plates that encompass continents and three plates that encompass only oceanic crust. Match the correct label with each plate. Pacific plate Philippine plate Nazca plate North America plate Africa Plate Eurasian Plate

Pacific - oceanic Philippine - Oceanic Nazca - Oceanic North America - Encompasses Continent Africa - Encompasses Continent Eurasian - Encompasses Continent

Which among the plates listed below is one of the largest plates on the Earth?

Pacific plate

________ occurs when magnetic minerals in lavas align their magnetic fields with magnetic north, preserving a record of that pole's location at that moment in time.

Paleomagnetism

What is the name of the supercontinent proposed by Alfred Wegener?

Pangaea

Why are volcanic chains associated with convergent boundaries?

Partial melting occurs due to subduction

Plate A has oceanic lithosphere on its leading edge that is 10 million years old. Plate B has oceanic lithosphere on its leading edge that is 200 million years old. Which plate will be subducted if they collide with each other, and why?

Plate B will subduct because it is older—and therefore colder—and more dense

How do plates move at divergent plate boundaries?

Plates move apart

How do plates move at convergent plate boundaries?

Plates move toward one another.

How do plates move at transform plate boundaries?

Plates slide past one another.

The three diagrams below show the three types of stresses: tension, compression, and shear. Determine which of these stresses would be found at transform plate boundaries, and place them in the appropriate bin. Drag the appropriate items into their respective bins. Each item may be used only once.

Question #43

Part C - Transform boundaries in convergent zones

Question #43 Part C

When the continents were assembled and mountain ranges were matched up, mountains in Scandinavia and the British Isles matched up perfectly with which North American mountain range?

Sierra Nevada Mountains

Which factor contributes the most toward plate motion at a convergent boundary?

Slab pull

How were scientists able to determine the date of the magnetic reversals during seafloor spreading?

Small marine fossils in deep-sea sediments give the age of the portions of the seafloor

What evidence supports that the glaciers on the southern continents were once part of a single, massive ice sheet?

Striations

What are two differences between oceanic crust and continental crust?

The continental crust is thicker and less dense than oceanic crust.

When matching up once-joined continents such as South America and Africa, the coastlines do not fit together as nicely as the continental shelves. Why might this be the case?

The continental shelves are the edges of the continent. The shoreline simply shows where the sea level is in relation to topography.

Which of the following best explains the global distribution of plant species, such as the Glossopteris, during the Mesozoic?

The landmasses were joined and the plant had a large geographic extent.

Why does oceanic lithosphere subduct under continental lithosphere, whereas continental lithosphere does not subduct under oceanic lithosphere?

The oceanic lithosphere is thinner and denser than the continental lithosphere, which is thicker and less dense.

At a subduction zone where oceanic lithosphere meets continental lithosphere, which would subduct and why?

The oceanic lithosphere would subduct because it has a higher density at 3.0 grams per cubic centimeter.

Which of the following pieces of evidence supports the plate tectonic theory?

The stripe patterns of high- and low-intensity magnetism are the same on both sides of an oceanic ridge.

What role do transform boundaries play?

Transform boundaries connect other segments of plate boundaries.

What is the relationship between transform boundaries and mid-ocean ridges?

Transform boundaries connect segments of mid-ocean ridges

Why are volcanoes NOT found at transform boundaries?

Transform boundaries do not cause changes to the pressure, temperature, or composition of the mantle.

Divergent boundaries are not one, smooth ridge of separation. Instead, they are broken into a series of segments, with different segments of fault offset from others. What features allow for the offset of divergent boundaries?

Transform faults

Late Paleozoic sedimentary rocks often contain extensive coal seams that were used to support the existence of Pangaea. What would the climate have been at that time and at the location where the coal deposits were formed, and what would it indicate about the continent's past latitude?

Warm, humid climate near the Equator

Why are the mid-ocean ridges higher in elevation than the surrounding ocean floor?

Warmer material near the ridge is less dense, so it is more buoyant on the mantle.

In Wegener's hypothesis of continental drift, how did the continents and the ocean floor move with respect to one another?

Wegener believed that the continents plowed through the thin ocean floor as they changed positions.

Which war was indirectly responsible for the development of the tools that made the theory of plate tectonics possible?

World War II

Which of the choices below is a feature of the oceanic ridge system?

a rift valley

What are plate boundaries at which lithospheric plates that a) move toward each other, b) move past each other, and c) move away from each other called?

a) convergent, b) transform, and c) divergent

Match the tectonic boundary with its direction of motion. a.Two plates move toward each other b.Two plates pull apart from each other c.Two plates slide past each other

a.Convergent boundary b.Divergent boundary c.Transform boundary

Match the tectonic boundary with the effect on the crust. a.Oceanic crust is being destroyed b.− Oceanic crust is being created c.Oceanic or continental crust is being conserved

a.Convergent boundary b.Divergent boundary c.Transform boundary

The East African rift is a divergent plate boundary that is splitting the continent of Africa into two pieces. What will eventually form around this divergent boundary?

an ocean

The ________ is a hotter, weaker region in the mantle that lies below the lithosphere and responds to forces by flowing.

asthenosphere

Where are tectonic plates located?

at Earth's surface

At which type of convergent plate boundary did the Himalaya mountain belt form, and why?

at a continental-continental convergent boundary, because the two continental plates buckled and thickened vertically when they collided

Which type of plate boundary is most closely associated with uplifting continental regions and mountain building?

convergent boundaries

Compared to the Earth's asthenosphere, the Earth's lithosphere is

cooler and more rigid

The lithosphere is composed of the ________ and the rigid part of the ________.

crust; upper mantle

A ________ is a geographic low, which marks the location where oceanic lithosphere descends into the mantle.

deep-ocean trench

In general, where do earthquakes AND volcanic eruptions occur? Choose all that apply.

divergent plate boundaries convergent plate boundaries

What are the three types of plate boundaries?

divergent, convergent, and transform

Continental crust is mainly composed of ________, whereas oceanic crust is mainly composed of ________.

granite; basalt

Which statement about the theory of plate tectonics is correct?

he rigid lithosphere plates overlay the hotter and weaker asthenosphere.

Which phenomenon can explain the presence of volcanoes in the middle of the Pacific Ocean

hot spots

What forms at divergent plate boundaries?

new oceanic lithosphere

In general, where do volcanoes form in subduction zones?

on the overriding plate, away form the convergent boundary

Oceanic lithosphere contains oceanic crust and the __________.

outermost part of mantle beneath the oceanic crust

Label the diagram below, which shows the last stage of continental rifting.

question #26

Match the oceanic and continental lithospheres with their positions on the figure below.

question #36

Identify each type of convergent plate boundary

question #39

Depending on the type of plate convergence, different features could result. Examples of these features include volcanic island arcs, continental volcanic arcs, and a collisional mountain chain. Drag and drop each of the following types of features to match the respective geologic formations. View Available Hint(s)

question #39 part B

Before the 1960s, how did geologists view the ocean basins and continents of the Earth?

scientists believed that all ocean basins and landmasses were permanently fixed in their positions.

When contrasting the forces slab pull with ridge push,

slab pull is a result of cool, dense rock overlaying warm asthenosphere and generates most of the force for subduction, whereas ridge push is the result of the elevated position of the ridge on the far side of the slab creating a decline down which the slab slides.

Transform boundaries are classified under which type of fault?

strike-slip

At a ________, an oceanic plate will be forced beneath another plate because of differences in density.

subduction zone

What evidence first indicated to scientists that the continents were once connected?

the apparent jigsaw-like fit of continents together, as in the case of South America and Africa

Which plate boundary is NOT associated with volcanic eruptions?

transform