Earth Layers Overview

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Questions and Answers

What is the primary composition of the inner core?

Molten iron and nickel

Solid metals primarily made of iron and nickel (correct)

Lava and minerals

Liquid metal with sulfur and oxygen

Which layer of the Earth is known for its flexibility and ability to flow like a viscous liquid?

Outer core

Inner core

Crust

Mantle (correct)

How thick is the Earth's crust beneath the oceans?

10-15 km

5-10 km

20-35 km

1-8 km (correct)

What temperature range does the outer core reach?

4000-9000°F Signup and view all the answers

Which of the following statements about the lithosphere is correct?

It consists of the crust and the upper mantle. Signup and view all the answers

What is the main factor driving the movement of tectonic plates?

Unequal distribution of heat within the Earth Signup and view all the answers

What distinguishes oceanic crust from continental crust?

Oceanic crust is thinner and denser. Signup and view all the answers

What is the athenosphere primarily composed of?

Molten rock and metal Signup and view all the answers

What is the primary composition of the continental crust?

Granite Signup and view all the answers

Which layer of the Earth is considered the rigid outer layer that includes both the crust and upper mantle?

Lithosphere Signup and view all the answers

What characteristic distinguishes oceanic crust from continental crust?

It is thinner and denser. Signup and view all the answers

What is the approximate annual movement rate of tectonic plates?

1 to 10 cm Signup and view all the answers

Which of the following phenomena are typically found along tectonic plate boundaries?

Volcanoes and earthquakes Signup and view all the answers

Which term refers to the long, steep-sided valleys on the ocean floor?

Trenches Signup and view all the answers

Which of the following best defines the term 'asthenosphere'?

A weaker region in the upper mantle Signup and view all the answers

What is the definition of an earthquake?

A vibration of the earth due to rapid energy release Signup and view all the answers

What happens to the age of ocean crust as one moves away from the oceanic ridge?

It increases with distance. Signup and view all the answers

How do rocks at the mid-ocean ridge compare in age to those found far away from it?

Rocks at the ridge are younger than those far away. Signup and view all the answers

What role does sonar play in oceanography?

It maps underwater structures by measuring echoes. Signup and view all the answers

What is the significance of magnetic reversals in oceanic crust formation?

They are preserved in rocks formed at mid-ocean ridges. Signup and view all the answers

What material primarily composes the oceanic crust?

Basalt Signup and view all the answers

How long does it normally take for Earth's magnetic field to reverse?

Every 500,000 years. Signup and view all the answers

What tool did scientists start using in the 1950s to measure the magnetism of the ocean floor?

Magnetometer Signup and view all the answers

What is the relationship between sediment thickness and distance from the mid-ocean ridge?

Sediments are thinner at the ridge. Signup and view all the answers

What is the name of the single large landmass that existed about 200 million years ago?

Pangaea Signup and view all the answers

Which fossil group did Alfred Wegener use as biogeographic evidence for continental drift?

Lystrosaurus Signup and view all the answers

What geological evidence supports the theory of continental drift by showing matching large-scale features across continents?

Rock Terrain Matching Signup and view all the answers

What do scientists believe drives the movement of tectonic plates?

Convection Currents Signup and view all the answers

Which evidence indicates that Antarctica was once in a much warmer climate?

Coal Deposits Signup and view all the answers

What type of geological feature can provide evidence of past glacial movement across continents?

Glacial Striations Signup and view all the answers

In which period did the geological changes leading to the current distribution of continents begin to significantly occur?

Jurassic Signup and view all the answers

What is the term for the theory that describes the gradual movement of the Earth's tectonic plates?

Plate Tectonics Signup and view all the answers

What primarily causes convection currents in the mantle?

Differences in temperature and density of materials Signup and view all the answers

What role does the slab pull force play in plate tectonics?

It causes a subducting plate to pull the trailing slab into the subduction zone Signup and view all the answers

What defines the asthenosphere?

A soft, weak, and plastic-like upper part of the mantle Signup and view all the answers

What happens during the process of seafloor spreading?

Hot, less dense material rises and creates a new seafloor Signup and view all the answers

What is the main characteristic of the lithosphere?

It is a rigid layer composed of the crust and upper mantle Signup and view all the answers

What initiates convection within the Earth's mantle?

The continual heating of materials from the Earth's core Signup and view all the answers

Which process results from the differences in density between old and new oceanic crust?

Ridge push Signup and view all the answers

What factors contribute to the movement of lithospheric plates?

Convection currents and tectonic forces Signup and view all the answers

Study Notes

Earth Layers

Earth consists of four main layers: Crust, Mantle, Outer Core, Inner Core.
Crust: The thin, solid outer layer, 5-35 km thick on land and 1-8 km thick beneath oceans, divided into tectonic plates.
Mantle: The thickest layer at 2900 km, consisting of the lithosphere and asthenosphere, with temperatures from 1600°F near the surface to 4000°F at the core.
Outer Core: A liquid layer of iron and nickel, 2,250 km thick, with temperatures between 4000-9000°F.
Inner Core: Solid due to extreme heat and pressure, primarily composed of iron and nickel.

The Mantle

Holds the lithosphere (rigid outer layer) and asthenosphere (semi-fluid layer).
The asthenosphere allows tectonic plates to move, functioning like a thick liquid.

Types of Crust

Two types: Continental Crust (thicker, less dense, granite-rich) and Oceanic Crust (thinner, denser, basalt-rich).
Continental crust is primarily old, while oceanic crust is formed at mid-ocean ridges and is comparatively younger.

Plate Tectonics Theory

Describes the movement of Earth’s lithosphere, which is broken into tectonic plates that interact at boundaries.
Movement causes earthquakes, volcanoes, and mountain ranges.
Plates move at rates of 1-10 cm per year due to uneven heat distribution in the Earth.

Continental Drift Theory

Proposed by Alfred Wegener, describes how continents were once joined as Pangaea.
Evidence includes:
- Geological fit of coastlines (e.g., South America and Africa).
- Fossil correlation showing similar species across continents.
- Coal deposits in Antarctica indicating a previously warmer climate.
- Glacial striations and deposits matching across separated landmasses.

Convection Currents

Drive the movement of tectonic plates.
Result from heat generated by the Earth's core, where hot material rises and cool material sinks.

Other Forces in Plate Movement

Slab pull: Heavier subducting plates pull down trailing slabs.
Ridge push: Older oceanic crust sinks due to weight from raised ridges.

Seafloor Spreading Theory

Suggests that magma rises at mid-ocean ridges, creating new oceanic crust and pushing existing crust sideways.
Evidence includes younger rocks and thinner sediments at mid-ocean ridges compared to older and thicker rocks further away.

Magnetic Reversal

Earth's magnetic field has reversed polarity every 500,000 years.
These reversals are recorded in the basaltic rocks of the ocean floor, supporting seafloor spreading.

Tools for Study

Sonar: Used to map the ocean floor by sending sound waves and measuring their echo.
Magnetometers: Measure the magnetic properties of ocean floor rocks.

Key Definitions

Geology: Scientific study of Earth’s origin, history, and structure.
Lithosphere: Rigid outer layer of Earth, comprising crust and upper mantle.
Mantle: Layer between crust and core, characterized by plasticity.
Tectonic: Relating to movements of Earth’s plates.

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Description

Explore the four main layers of the Earth: the crust, mantle, outer core, and inner core. This quiz covers the characteristics of each layer, including their thickness, composition, and temperature. Test your knowledge about the Earth's structure and its unique features!