Geology Chapter 5 Quiz

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Questions and Answers

What is the primary composition of the oceanic crust?

Granite

Sedimentary rock

Metamorphic rock

Basalt (correct)

Which layer of the Earth contributes to the movement of lithospheric plates?

Outer core

Continental crust

Inner core

Middle mantle (asthenosphere) (correct)

What characteristic of the continental crust makes it less dense than the oceanic crust?

Presence of less heavy metals

Composition mainly of granite (correct)

Composition mainly of basalt

Thickness greater than oceanic crust

What is the thickness range of the oceanic crust?

3-5 miles Signup and view all the answers

What is the layer beneath the lithosphere called?

Asthenosphere Signup and view all the answers

In what state are the metals in the outer core?

Liquid Signup and view all the answers

How does the middle mantle facilitate the movement of the lithospheric plates?

Convection currents Signup and view all the answers

What causes the inner core to remain solid despite extreme temperatures?

High levels of pressure Signup and view all the answers

What type of rock is formed when sediments are pressed together over time?

Sedimentary rock Signup and view all the answers

Which process primarily contributes to the formation of metamorphic rocks?

High temperatures and pressures Signup and view all the answers

What is the difference between volcanic rocks and plutonic rocks?

Volcanic rocks originate from magma that cools quickly. Signup and view all the answers

What is one of the primary components that make up the structure of rocks?

Mineral crystals Signup and view all the answers

What is the main characteristic of sedimentary rocks regarding their formation environment?

They generally form at low temperatures and pressures. Signup and view all the answers

What is the primary characteristic of divergent boundaries?

Tectonic plates pull away from each other. Signup and view all the answers

What geological feature is commonly associated with subduction zones?

Deep-ocean trenches Signup and view all the answers

In which scenario does oceanic lithosphere typically get subducted?

Ocean plate collides with less dense continental plate. Signup and view all the answers

What is a common feature of divergent plate boundaries?

Rift valleys Signup and view all the answers

What process describes the sinking of an ocean floor into the mantle?

Subduction Signup and view all the answers

Which of the following best describes transform boundaries?

They're formed by plates sliding past each other. Signup and view all the answers

What happens to the oceanic plate as it enters a subduction zone?

It heats and dehydrates as it descends. Signup and view all the answers

Which type of plate boundary is mostly located along the mid-ocean ridge?

Divergent boundaries Signup and view all the answers

What geological feature forms when an oceanic plate sinks under another oceanic plate?

Trench Signup and view all the answers

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

Himalayas Signup and view all the answers

What type of boundary occurs when two tectonic plates slide past each other?

Transform boundary Signup and view all the answers

Which phenomenon is most commonly associated with the Pacific Ring of Fire?

Volcanism Signup and view all the answers

Which of the following describes the process of oceanic plates crashing into each other?

Convergent collision Signup and view all the answers

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

5 cm per year Signup and view all the answers

What geological consequence is likely to occur along the San Andreas Fault?

Earthquakes Signup and view all the answers

Which of the following features is specifically associated with transform plate boundaries?

Earthquakes Signup and view all the answers

What was Alfred Wegener's primary hypothesis regarding the continents?

The continents were once connected as a single landmass. Signup and view all the answers

Which of the following provides evidence for the theory of continental drift?

Matching fossils found on different continents. Signup and view all the answers

What geological evidence supports Wegener's theory about the continents?

Matching rock types and ages in distant mountain ranges. Signup and view all the answers

What climatic evidence did Wegener use to support his theory?

The discovery of tropical plant remains in Antarctica. Signup and view all the answers

Which of the following is a characteristic of sea-floor spreading?

Ocean floor is constantly being pushed away from mid-ocean ridges. Signup and view all the answers

How did Wegener explain the presence of glacial deposits in now warm regions?

Continents were once located near the poles but drifted to their current positions. Signup and view all the answers

What was a significant reason why many scientists rejected Wegener's continental drift theory at first?

There was insufficient evidence to support his claims. Signup and view all the answers

What can be inferred about the Mesosaurus based on fossil evidence?

It was limited in its habitat due to geographical barriers. Signup and view all the answers

What primarily causes hotspot volcanoes to form?

Hot mantle plumes breaching the surface Signup and view all the answers

How are earthquakes distributed globally?

In linear patterns associated with plate boundaries Signup and view all the answers

What is a defining characteristic of tsunami waves as they enter a narrow harbor?

They can reach greater heights Signup and view all the answers

Which of the following processes is NOT part of the rock cycle?

Formation of oceanic crust Signup and view all the answers

What type of rock is formed from cooled magma and lava?

Igneous rock Signup and view all the answers

Which change can metamorphic rock undergo in the rock cycle?

Change into sedimentary rock or igneous rock Signup and view all the answers

What triggers the occurrence of earthquakes at plate boundaries?

Friction causing energy build-up Signup and view all the answers

What happens when a shallow focus earthquake displaces oceanic crust?

Large volumes of water are displaced Signup and view all the answers

Study Notes

Earth's Layers

Earth is made of many distinct layers, with deeper layers composed of heavier materials, hotter, denser, and under greater pressure.
Natural forces interact with the crust, shaping landforms.

Earth's Crust

The crust is Earth's rigid, rocky outer layer composed of two main rock types: granite (continental crust) and basalt (oceanic crust).
Basalt is denser than granite, causing less dense continents to rest on denser oceanic plates.
The crust is 3-5 miles (8 kilometers) thick under the oceans and about 25 miles (32 kilometers) thick under the continents.

Lithospheric Plates

Earth's crust is broken into many pieces called plates.
These plates "float" on the soft, semi-rigid asthenosphere, the upper mantle.
The crust and upper mantle together make up the lithosphere.

Mantle

The mantle is Earth's largest layer, composed of silicon, oxygen, magnesium, iron, aluminum, and calcium.
The middle mantle, or asthenosphere, is made of very hot, dense rock that flows like asphalt under pressure; this movement is the reason for plate movement.
Convection currents within the mantle cause material to rise, then cool and sink, repeating this movement cycle.

Core

The core is like a ball of very hot metals, composed of two layers: outer and inner.
The outer core is liquid, primarily composed of melted nickel and iron.
The inner core is solid, also composed mostly of nickel and iron; high temperature and immense pressure prevent it from becoming liquid.

Continental Drift Theory

Alfred Wegener proposed the continental drift theory in the 1900s, suggesting that Earth's continents were once part of a single supercontinent (Pangaea) and have drifted to their present positions.
Evidence supporting the theory includes puzzle-like fit of continents, matching fossils across oceans, similar rock types and mountain ranges, and climate evidence from glacial deposits.
Wegener's theory was initially rejected for lack of a mechanism for continental movement.

Evidence of Continental Drift

Continents fit together like a jigsaw puzzle, particularly the coastlines of Africa and South America.
Fossils of similar plant and animal species are found on separated continents, suggesting these continents were once joined.
Matching rock types and mountain ranges across continents provide further evidence for their past connections.
Evidence of past glacial deposits on widely separated continents.

Sea-Floor Spreading

Harry Hess proposed sea-floor spreading in the 1960s, suggesting that new oceanic crust is formed at mid-ocean ridges, pushing older crust away.
Molten material erupts from the mantle, creating new crust at mid-ocean ridges, pushing older crust to the sides.
This process results in ocean floors moving like a conveyor belt, carrying continents along with it.

Evidence of Sea-Floor Spreading

Molten rock eruptions at mid-ocean ridges create "pillows" that quickly cool and solidify.
Mid-ocean ridges are mountain ranges in the ocean floor.
Magnetic stripes on the seafloor document reversals in Earth's magnetic field over time.
Drilling samples show that the oldest rocks are located farthest from mid-ocean ridges, and youngest rocks are located nearest to mid-ocean ridges.

Plate Tectonic Theory

Plate tectonic theory combines continental drift and sea-floor spreading.
Earth's lithosphere is broken into large and smaller pieces called tectonic plates, constantly moving but slowly, often imperceptible to humans.
These plates slide over the asthenosphere (part of the upper mantle), driven by convection currents in the mantle.

Plate Boundaries

Three types of plate boundaries:
- Divergent: Plates move apart (e.g., mid-ocean ridges)
- Convergent: Plates collide (e.g., subduction zones)
- Transform: Plates slide past each other (e.g., San Andreas Fault)

Mechanisms of Plate Boundaries

Divergent Boundaries: Plates move apart; rifting causes seafloor spreading; features include mid-ocean ridges, rift valleys, and fissure volcanoes.
Convergent Boundaries: Plates collide; types include:
- Ocean-Continent Collision: Oceanic plate slides under the continental plate (subduction) forming volcanoes and trenches.
- Ocean-Ocean Collision: One oceanic plate slides under the other forming volcanoes and trenches.
- Continent-Continent Collision: Two continental plates collide forming mountain ranges.
- Transform Boundaries: Plates slide past each other; features include earthquakes and faults, like the San Andreas Fault.

Consequences of Plate Tectonics

Pacific Ring of Fire: Active volcanoes mostly along the margins of the Pacific plate, reflecting the numerous plate boundaries near the Pacific Ocean.
Hotspot Volcanoes: Volcanoes that occur in the middle of tectonic plates; these volcanoes are not related to plate boundaries; they are caused by mantle plumes.
Global Distribution of Earthquakes: Occur mostly along plate boundaries, often reflecting plate movement and friction.
Tsunami Formation: Earthquakes on the ocean floor can displace large volumes of water, generating powerful waves that can inundate coastlines.

The Rock Cycle

A continuous series of changes, involving weathering, erosion, deposition, compaction, cementation, and heat and pressure, that transforms rocks from one type to another.
Three main rock types:
- Igneous
- Sedimentary
- Metamorphic

Types of Rocks

Igneous Rocks: Formed from cooled magma or lava. Two types:
- Volcanic (extrusive): Cooled rapidly on the Earth's surface.
- Plutonic (intrusive): Cooled slowly beneath the Earth's surface.
Sedimentary Rocks: Formed from sediments (sand, gravel, mud) compacted and cemented together.
Metamorphic Rocks: Formed when existing rocks are altered by heat and pressure within Earth's crust.

Rock Parts

Crystals: Formed from atoms in a definite geometric pattern.
Grains: Small pieces of rock or sediment that can be used to classify rock types.

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Description

Test your knowledge on the Earth's crust and its layers in this engaging quiz. Explore topics such as plate tectonics, rock types, and the composition of the oceanic and continental crusts. Perfect for students looking to reinforce their understanding of geological processes.