Plate Tectonics Quiz

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Questions and Answers

What is formed when one oceanic plate subducts beneath another oceanic plate?

Ocean ridges

Volcanic islands

Mountain ranges

Subduction zone (correct)

What geological feature is associated with oceanic trenches?

Deep depressions (correct)

Rift valleys

Shallow waters

Mountain ranges

Which mountain range was formed by the collision of two continental plates?

Himalayas (correct)

Appalachian Mountains

Andes Mountains

Rocky Mountains

What type of boundary exists where two tectonic plates slide past each other?

Transform boundary Signup and view all the answers

Which phenomenon is most likely to occur along transform boundaries?

Earthquakes Signup and view all the answers

What feature marks the boundaries of the Pacific tectonic plate?

The San Andreas Fault Signup and view all the answers

What is the rate at which the Indo-Australian Plate pushes against the Eurasian Plate?

5 cm per year Signup and view all the answers

Where is volcanism mainly focused according to plate tectonics?

At plate margins Signup and view all the answers

What geological feature is created at a divergent plate boundary?

Rift valleys Signup and view all the answers

What mechanism occurs when an oceanic plate collides with a continental plate?

Subduction Signup and view all the answers

Which type of boundary occurs when tectonic plates slide past one another?

Transform boundary Signup and view all the answers

Which natural phenomenon is associated with subduction zones?

Volcanism Signup and view all the answers

What is created as the ocean floor sinks back into the mantle at a subduction zone?

Deep-ocean trenches Signup and view all the answers

Which of the following describes the movement at divergent boundaries?

Plates pull away from each other Signup and view all the answers

What is the primary process involved in seafloor spreading?

Rifting Signup and view all the answers

Which feature would you find at an ocean to ocean collision?

Island arcs Signup and view all the answers

What phenomenon describes the movement of the ocean floor carrying continents with it?

Sea-floor spreading Signup and view all the answers

What evidence indicates that molten material has erupted from the ocean floor?

Rock formations shaped like pillows Signup and view all the answers

At what type of plate boundary is new ocean floor created?

Divergent boundary Signup and view all the answers

What is located along the mid-ocean ridge system?

The most extensive chain of mountains Signup and view all the answers

What do the magnetized stripes on the ocean floor record?

The reversals in Earth’s magnetic field Signup and view all the answers

What is the main hypothesis of the continental drift theory proposed by Alfred Wegener?

Continents are part of a single supercontinent that once existed. Signup and view all the answers

Where are the oldest rocks found in relation to the mid-ocean ridge?

Farther from the ridge Signup and view all the answers

What does the plate tectonic theory primarily explain?

The movement and interactions of the Earth’s landmasses Signup and view all the answers

Which of the following is NOT a piece of evidence for continental drift?

Uniform climate patterns across all continents. Signup and view all the answers

What is the typical rate at which the plates spread apart at mid-ocean ridges?

1 cm to 20 cm per year Signup and view all the answers

How did Wegener use the concept of fossils to support his theory?

Fossils of the same species found on opposite sides of the ocean. Signup and view all the answers

Which geologic features helped Wegener support his hypothesis about the existence of Pangaea?

Mountain ranges ending at coastlines and reappearing on distant continents. Signup and view all the answers

What climate evidence was found that supported Wegener's theory of continental drift?

Glacial deposits found in now tropical regions. Signup and view all the answers

What concept did Harry Hess introduce in the 1960s that relates to continental drift?

Sea-floor spreading. Signup and view all the answers

What was primarily responsible for the rejection of Wegener's theory during his time?

Inability to explain the mechanism of continental movement. Signup and view all the answers

Which of the following statements about Pangaea is accurate?

Pangaea eventually broke apart due to continental drift. Signup and view all the answers

What characterizes igneous rocks formed from lava?

They can feature a glassy or crystalline texture. Signup and view all the answers

Sedimentary rocks are primarily formed through which process?

Compaction of sediments over time. Signup and view all the answers

What is the role of heat and pressure in the formation of metamorphic rocks?

They help to change the mineral structure and physical properties. Signup and view all the answers

What distinguishes plutonic rocks from volcanic rocks?

Plutonic rocks crystallize at a slower pace within the earth's crust. Signup and view all the answers

Which of the following is NOT a common component of rock properties?

Layers of sediment Signup and view all the answers

What defines a hotspot volcano?

A volcano resulting from hot mantle plumes breaching the surface Signup and view all the answers

How does the distribution of earthquakes differ from that of volcanoes?

Earthquakes are found at tectonic plate boundaries, while volcanoes can be anywhere Signup and view all the answers

What is the primary cause of tsunami formation?

A shallow focus earthquake displacing a large volume of oceanic crust Signup and view all the answers

Which type of rock can metamorphose into igneous rock?

Metamorphic rock through melting Signup and view all the answers

What is NOT a component of the rock cycle?

Ignition Signup and view all the answers

Which characteristic do hotspot volcanoes share with traditional volcanoes?

Both types can produce lava and ash flows Signup and view all the answers

Which of these is an example of an igneous rock formation process?

Cooling and solidification of magma and lava Signup and view all the answers

How do tsunamis behave when they enter a narrow harbor?

They can reach greater heights compared to open coastlines Signup and view all the answers

Study Notes

Earth's Layers

The Earth is made of distinct layers with deeper layers being composed of heavier materials, hotter, denser, and under greater pressure
Natural forces affect the Earth's crust, creating landforms

Earth's Crust

The crust is the Earth's rigid outer surface, rocky and made of two main rock types:
- Continental crust (mostly granite)
- Oceanic crust (basalt)
Basalt is denser than granite, and this is why less dense continents ride on denser oceanic plates
The crust is 3-5 miles (8 km) thick under the oceans and about 25 miles (32 km) thick under the continents

Lithospheric Plates

The Earth's crust is broken into many pieces called plates
These plates "float" on the soft, semi-rigid asthenosphere
The crust and the upper layer of the mantle make up the lithosphere, it is brittle and rigid
There are several large plates and numerous smaller ones

Mantle

The mantle is the largest layer of the Earth, composed of silicon, oxygen, magnesium, iron, aluminum, and calcium
The middle mantle is made of hot, dense rock that flows like asphalt
Convection currents in the middle mantle (asthenosphere) cause the Earth's crustal plates to move
Convection currents are caused by very hot material in the deepest part of the mantle rising, cooling and sinking (repeating cycle)

Core

The core is like a ball of very hot metals composed of two layers:
- Outer core: so hot that the metals are in liquid state. The outer core is primarily composed of nickel and iron.
- Inner core: temperatures and pressures are so great that metals are squeezed together, not able to move, but forced to vibrate in place as solids

Continental Drift Theory

German scientist Alfred Wegener proposed the continental drift theory in the 1900s
He hypothesized that the Earth was once a single supercontinent (Pangaea)
Wegener believed Pangaea floated on the oceanic crust like an iceberg
Most scientists at the time rejected the theory due to a lack of evidence

Evidence of Continental Drift

Continents fit together like a puzzle
Fossils match across oceans
Rock types and mountain ranges match across oceans
Climate evidence found in glacial deposits
Ocean floor spreading

Sea-Floor Spreading

The process adds new material to the ocean floor while pushing older rocks away from a ridge
New ocean floor forms along cracks in the ocean crust
Molten material erupts from the mantle, spreading outward, pushing older rocks to the sides of the crack
This process happens continuously, causing the ocean floor to move like a conveyor belt, carrying continents
Harry Hess (1960s)

Evidence of Sea-Floor Spreading

Rocks shaped like pillows (rock pillows) show that molten material has erupted numerous times from cracks along the mid-ocean ridge and cooled quickly
The mid-ocean ridge system is the most extensive chain of mountains on earth. More than 90% are in the deep ocean, extending over 65,000 km
It occurs along plate boundaries where new ocean floor is created as plates spread apart (divergent plate boundary)
Plates spread apart at rates ranging from 1 cm to 20 cm per year
As plates move apart, rock melts, rising from tens of kilometers deep

Evidence from Magnetic Stripes

Rocks that make up the ocean floor lie in a pattern of magnetized stripes. These stripes hold a record of magnetic field reversals in Earth.

Evidence from Drilling Samples

Core samples from the ocean floor show that older rocks are found farther from the ridge; the youngest rocks are in the center of the ridge

Plate Tectonic Theory

The idea that the Earth's landmasses have broken apart, rejoined, and moved to other parts of the globe.
Pieces of Earth's top layer are called tectonic plates. They move very slowly.
Along the mid-ocean ridge, the seafloor is pulling apart, and the two parts are moving in opposite directions, carrying continents and oceans.
Earth's surface layers are currently divided into nine large and several smaller plates

Earth's Major Plates

The Earth's plates are not anchored in place. They slide over a hot, bendable layer of the mantle.

Plate Boundaries

There are three main types of plate boundaries:
- Divergent (pulling away from each other)
- Convergent (crashing head-on)
- Transform (sliding past each other)

Mechanisms of Divergent Boundaries

Boundary between two plates moving apart or rifting
Rifting causes seafloor spreading
Features of divergent boundaries include mid-ocean ridges, rift valleys, and fissure volcanoes

Pulling Apart

When plates pull away from one another, they form a diverging plate boundary or spreading zone
Iceland has a divergent plate boundary running through its middle, with Thingvellir as an example

Mechanisms of Convergent Boundaries

Boundaries between two colliding plates
There are three types: ocean-to-continent collision, ocean-to-ocean collision, and continent-to-continent collision

Ocean to Continent Collision

Ocean plate colliding with a less dense continental plate
Subduction zone: where the denser oceanic plate slides under the less dense continental plate. It heats and dehydrates as it subsides
Volcanoes occur at subduction zones
Deep ocean trenches are also found here

Continental/Oceanic Crush

Subduction. Process of ocean floor sinking beneath a deep ocean trench and into the mantle
Deep Ocean Trench. It occurs at subduction zones where deep underwater canyons are formed due to bending of oceanic crust downward

Ocean to Ocean Collision

When an ocean plate collides with another ocean plate, the denser plate slides under the less dense plate (subduction zone)
The subducting plate bends downward forming a deep depression in the ocean floor (trench)
The world's deepest parts of the ocean are found along trenches

Both Oceanic Plates Crash (Converge)

When both plates are oceanic, one slides under the other.
Often, an island group forms at this boundary

Continent to Continent Collision

A continental plate colliding with another
Plates push against each other, causing the formation of mountain ranges (such as the Himalayas and the European Alps)

Both Continental Plates Crash (Converge)

Earth's highest mountain range, the Himalayas, was formed millions of years ago when the Indo-Australian plate collided with the Eurasian plate
This collision is still occurring at a rate of about 5 cm per year

Mechanisms of Transform Boundaries

Boundary between two plates that are sliding past each other
Earthquakes occur along faults

Transform Boundary

The San Andreas Fault is an example of a transform boundary where the North American and Pacific plates slide past each other at a rate of 5-6 cm per year

Consequences of Plate Tectonics

Pacific Ring of Fire: Shows the margins of the Pacific tectonic plate and surrounding area, where active volcanism is focused along plate boundaries
Hotspot Volcanoes: Hot mantle plumes rising to the surface in the middle of tectonic plates (e.g., Hawaiian Islands)

Global Distribution of Earthquakes

Earthquakes occur along faults in the boundaries of plates. These patterns resemble the Pacific Ring of Fire volcanism region.

Tsunami Formation

Huge mass of water with tremendous momentum
Shallow-focus earthquake
Large volume of oceanic crust displaced
The movement of the crust also displaces a large volume of water
Tsunamis reach greater heights in narrow spaces
Open coastline = 8m wave, narrow harbor = 30m

The Rock Cycle

A continuous cyclical change of rocks from one type to another through: chemical, organic, cementation, pressure, compaction, heating, cooling, transformation, melting, weathering, decomposition
The process of rocks changing from one type to another
Igneous, Sedimentary, and Metamorphic rocks are involved

Types of Rock

Igneous
Sedimentary
Metamorphic

Igneous Rock

Formed by magma and lava cooling
Two types
- Rock from lava cools very fast, light/airy, or crystal (glassy)
- Rock from magma forms underground, mostly hard, multiple colors

Sedimentary Rock

Made when sediments (sand, gravel, and dirt) are pressed together over time
Forms in layers near the Earth's surface at low temperatures and pressures
Can be formed by precipitation, water, wind or ice, and biological processes

Metamorphic Rock

Made from other rocks through intense heat and pressure in the Earth's crust
Heat and pressure change the mineral structure and physical properties of the parent rock without changing the chemical makeup

Rocks Classification

Volcanic rocks: extrusive, form from lava
Plutonic rocks: intrusive, form from magma
Rock Parts
- Crystals
- Grains

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Description

Test your knowledge on the fundamentals of plate tectonics, including subduction, oceanic and continental plates, and geological features. This quiz covers various concepts related to the movement of tectonic plates and associated phenomena. Perfect for students diving into Earth Sciences!