Earth Science Chapter 14 Study Guide

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Questions and Answers

What is the location of the crust?

Outermost layer of the Earth, about 22 miles thick, made up of silicon and oxygen. It includes continental crust (light colored rocks like granite) and oceanic crust (denser rocks like basalt).

What is the location of the mantle?

Located below the crust, the mantle is the largest layer (about 2900 km thick), hotter and denser than the crust, and composed mainly of magnesium and iron.

What is the location of the lithosphere?

The uppermost part of the mantle, thin and cooler, which floats on the asthenosphere and is involved in magma formation.

What is the location of the asthenosphere?

A hot, weak zone located directly under the lithosphere that flows very slowly. Signup and view all the answers

What is the location of the core?

Located deep within the Earth, made mostly of nickel and iron, and twice as dense as the mantle. Signup and view all the answers

What are the three types of rocks and their examples?

<ol> <li>Igneous (examples: basalt, obsidian), 2) Metamorphic (examples: gneiss, marble), 3) Sedimentary (examples: conglomerate, limestone).</li> </ol> Signup and view all the answers

Describe the rock cycle starting with igneous rock.

Igneous rocks can melt to form magma, which cools to form new igneous rocks. Metamorphic rocks form from heat and pressure acting on igneous or sedimentary rocks. Sedimentary rocks are formed from weathering and erosion processes. Signup and view all the answers

What are reserves of mineral resources?

Identified deposits of minerals extracted for profit, with depletion time being the time it takes to use 80% of reserves at a given rate. Signup and view all the answers

Describe the conventional view of the relationship between mineral supply and market price.

Developed countries use subsidies, tax breaks, and import tariffs to manage supply and combat high prices. Signup and view all the answers

What are lower-grade ores and how can they be harvested?

Lower-grade ores have smaller concentrations of metals, and they can be harvested using improved mining techniques such as biomining. Signup and view all the answers

How can the ocean be mined for minerals?

Hydrothermal ore deposits are formed by superheated mineral-rich water in volcanic regions. Minerals like copper and zinc can be found near hot water vents. Signup and view all the answers

Compare surface mining and subsurface mining.

Surface mining clears vegetation and rock to access minerals, while subsurface mining removes deep deposits through tunnels and shafts. Signup and view all the answers

What are the environmental impacts of surface and subsurface mining?

Both produce waste material and disturb land, with surface mining causing more extensive damage like sinkholes. Signup and view all the answers

Explain different types of surface mining.

Open-pit mining digs large holes for metal ores; strip mining extracts horizontal deposits; area strip and contour strip are techniques for flat and hilly terrains, respectively. Signup and view all the answers

What is smelting and its major environmental effects?

Smelting is the heating of ores to release metals, causing air pollution and contributing to acid rain. Signup and view all the answers

Discuss the benefits of recycling minerals.

Recycling has lower environmental impacts compared to mining; it significantly reduces air and water pollution and energy consumption. Signup and view all the answers

How can nonrenewable mineral resources be used more sustainably?

By increasing prices and using government interventions like subsidies and tariffs. Signup and view all the answers

What are examples of substitutes for nonrenewable mineral resources?

Taconite as a substitute for high-grade iron, silicon replacing some metals, and fiber optic cables replacing copper. Signup and view all the answers

What are tectonic plates?

Sections of the Earth's crust and upper mantle that move around on top of the mantle. Signup and view all the answers

Explain each type of plate boundary with examples.

Divergent boundaries (e.g., mid-ocean ridges) create new land; convergent boundaries (e.g., Andes Mountains) occur where plates collide; transform boundaries cause earthquakes. Signup and view all the answers

What causes a volcano?

Magma rises through the lithosphere and reaches the surface through vents, forming lava. Signup and view all the answers

What causes an earthquake and how is it measured?

Stress inside the mantle causes breakage in the crust, releasing energy as seismic waves, measured by amplitude on the Richter scale. Signup and view all the answers

What causes a tsunami, and how can it be detected?

Tsunamis are generated by sudden ocean floor movements, often caused by underwater earthquakes, and detected by ocean buoy networks. Signup and view all the answers

Study Notes

Earth's Layers and Structure

Crust: Outermost layer, approximately 22 miles thick, consists mainly of silicon and oxygen. Includes continental (light-colored rocks like granite) and oceanic crust (denser rocks like basalt).
Mantle: Below the crust, around 2900 km thick, hotter and denser due to increased temperature and pressure. Composed of movable rock layers, primarily magnesium and iron.
Lithosphere: Uppermost part of the mantle, thinner and cooler, floats on the asthenosphere, where magma is formed from melting rocks.
Asthenosphere: Below the lithosphere, a hot, weak zone that flows slowly, allowing the lithosphere to move.
Core: Deep within the Earth, made of nickel and iron, outer core is molten and generates the magnetic field; inner core is solid due to pressure.

Types of Rocks

Igneous Rocks: Formed from cooled magma, may lack crystals or have trapped gas bubbles. Examples include basalt and obsidian.
Metamorphic Rocks: Created through heat and pressure, often display ribbon-like layers and shiny crystals. Examples are gneiss and marble.
Sedimentary Rocks: Formed from compacted sediments, typically soft and crumbly. Examples include conglomerate and limestone.

The Rock Cycle

Igneous Formation: Magma cools to create igneous rock; metamorphic rock can melt back into magma.
Metamorphic Formation: Originates from heat and pressure on igneous or sedimentary rocks.
Sedimentary Formation: Formed through weathering and erosion of existing rocks, which creates sediments that compact and cement into sedimentary rock.

Mineral Resources and Sustainability

Mineral Reserves: Identified deposits that can be extracted profitably.
Depletion Time: Period it takes to use 80% of mineral reserves; influenced by recycling and economic viability.
Lower-Grade Ores: Contain smaller concentrations of minerals; can be mined through advanced techniques like biomining.
Ocean Mining: Involves extracting minerals from hydrothermal ore deposits and sediments on the ocean floor, including valuable metals like copper and zinc.

Mining Techniques and Environmental Impact

Surface Mining: Clears vegetation and soil, leading to significant land disturbance and pollution; uses 90% of non-fuel resources in the US.
Subsurface Mining: Extracts deeper mineral deposits with less land disturbance but risks explosions and groundwater contamination.
Environmental Consequences: Both methods generate waste, cause pollution, and damage ecosystems, with surface mining having a greater overall impact.

Specific Surface Mining Techniques

Open-Pit Mining: Large holes dug to retrieve metal ores and minerals, causing extensive environmental damage.
Strip Mining: Removes horizontal beds of minerals; leads to land and water resource damage.
Area Strip Mining: Flattens terrain for mining and results in high waste generation.
Contour Mining: Developed on hilly terrains, creates terraces and can lead to significant land alteration.
Mountaintop Removal Mining: Destroys ecosystems by removing mountain tops to extract coal, increasing flooding risk.

Smelting and Recycling

Smelting: Process of heating ores to release metals, causing air pollution and acid rain.
Recycling Benefits: Reduces environmental impact, significantly cuts pollution and energy consumption compared to new mining.

Tectonic Plates and Geological Phenomena

Tectonic Plates: Sections of the Earth's crust and upper mantle that move on the mantle, divided into oceanic and continental plates.
Plate Boundaries:
- Divergent: Plates move apart, creating mid-ocean ridges and rift valleys.
- Convergent: Plates collide, resulting in mountain ranges (e.g., Andes, Himalayas) and subduction zones (e.g., Aleutian Islands).
- Transform: Plates slide past each other, typically causing earthquakes.

Volcanoes and Earthquakes

Volcano Formation: Caused by rising magma that reaches the surface through fissures, often building into a cone and producing eruptions.
Earthquake Causes: Result from stress on rocks due to mantle forces, creating seismic waves measured by seismic instruments like the Richter scale.

Tsunamis

Tsunami Formation: Large waves generated by sudden ocean floor movements due to earthquakes or landslides.
Description and Detection: Waves slow down in shallow waters, causing height increases; detected using ocean buoys and pressure recorders for early warning systems.

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Description

This study guide focuses on the crust of the Earth, detailing its composition, density, and the distinctions between continental and oceanic crust. Ideal for students reviewing key concepts in Earth Science, it provides insights into the outermost layer of our planet.