Geology and Nonrenewable Minerals Chapter 12

Three big ideas • Dynamic forces move matter, recycle the earth’s rocks,

form deposits of mineral resources, and cause volcanic eruptions, earthquakes, and tsunamis.

• Mineral availability depends on quantity in the earth’s crust, rate of use, mining technology, market prices, and the harmful environmental effects of removing/using it.

• We can use mineral resources more sustainably by

trying to… find substitutes for scarce resources, reducing waste, and reusing and recycling nonrenewable minerals.

What are the earth’s major geological processes and hazards?

Section 12-1

The earth is a dynamic planet

• Geology is the science of earth’s surface and in its interior (non-living).

• Three major concentric zones. 1. The core is the earth’s innermost zone—

extremely hot. 2. Surrounding the core is a thick zone called the

mantle—solid rock… but part is the asthenosphere, a zone of hot, partly melted rock that flows.

The earth is a dynamic planet

3. The outermost and thinnest zone of the earth is the crust. • Continental crust, which underlies the continents. • Oceanic crust, which underlies the ocean basins and

makes up 71% of the earth’s crust. – The combination of the crust and the rigid

outermost part of the mantle (above the asthenosphere) is called the lithosphere.

The earth’s crust is made up of a mosaic of huge rigid plates

The earth beneath your feet is moving

• Convection cells or currents move large volumes of rock and heat in loops within the mantle like gigantic conveyer belts… this powers continental drift

• Plates can move/respond differently

Major features of the earth’s crust and upper mantle

The earth’s major tectonic plates

The San Andreas Fault

Internal pressure in a volcano can cause lava, ash, and gases to be ejected

An earthquake has certain major features and effects

What is the Richter scale?

Earthquakes are geological rock-and-roll events

– Insignificant (< 4.0 on the Richter scale). – Minor (4.0–4.9). – Damaging (5.0–5.9). – Destructive (6.0–6.9). – Major (7.0–7.9). – Great (over 8.0).

Earthquakes are geological rock-and-roll events

• The largest recorded earthquake occurred in Chile on May 22, 1960 and measured 9.5 on the Richter scale.

http://www.neptunuslex.com/

Google Earth… Why?

How a tsunami forms

What is a tidal wave?

Banda Aceh before and after the tsunami of December 2004

Earthquakes & Tsunami impacts

• What can be done to minimize impacts of these geologic events?

• Are they random?

How are the earth’s rocks recycled?

Section 12-2

Minerals, rocks & “dirt”

• A mineral is an element or inorganic compound that occurs naturally in the earth’s crust as a solid with a regular internal crystalline structure.

• Some are of a single element such as…?

• Most of the more than 2,000 identified minerals occur as inorganic compounds formed by various combinations of elements, such as…?

There are three major types of rocks

• Rock is a solid combination of one or more minerals found in the earth’s crust. – Some kinds of rock contain only one mineral

(examples? ) – Most consist of two or more minerals, such as

? – Three broad classes:

• Sedimentary rock (e.g. sandstone, limestone). • Igneous rock (e.g. granite). • Metamorphic rock (e.g. slate, marble).

Simplified rock cycle

WHAT ARE MINERAL RESOURCES AND WHAT ARE THE ENVIRONMENTAL EFFECTS OF USING THEM?

Section 12-3

We use a variety of nonrenewable mineral resources

• A mineral resource is a concentration of naturally occurring material from the earth’s crust. – Found and extracted more than 100 minerals from

the earth’s crust. – Examples are fossil fuels (such as ?), metallic

minerals (such as ?), and nonmetallic minerals (such as ?).

– Minerals are classified as nonrenewable resources. Why?

We use a variety of nonrenewable mineral resources

• An ore is rock that contains a large enough concentration of a particular mineral—often a metal—to make it profitable for mining and processing. – High-grade ore contains a large concentration

of the desired mineral. – Low-grade ore has a smaller concentration.

We use a variety of nonrenewable mineral resources

– What are some examples?

Each metal resource that we use has a life cycle

Harmful effects of extraction, processing, and use of nonrenewable mineral or energy resources

Types of mining Open pit, strip, contour strip, and mountaintop removable

Mining has harmful environmental effects

• What are the negative/harmful effects?

Video clip…

Removing metals from ores has harmful environmental effects

• Ore mining typically has two components: – Ore mineral, containing the desired metal. – Waste material.

• Removing the waste material from ores produces waste piles called tailings (chatt).

• Heating ores to release metals is called smelting. – Without effective pollution control equipment, smelters

emit enormous quantities of air pollutants, including sulfur dioxide and suspended particles.

• Chemicals can be used to remove metals from their ores.

HOW LONG WILL SUPPLIES OF NONRENEWABLE MINERAL RESOURCES LAST?

Section 12-4

Mineral resources are distributed unevenly

• What is abundant?

• What is NOT abundant?

Mineral resources are distributed unevenly

• Five nations—the United States, Canada, Russia, South Africa, and Australia—supply most of the nonrenewable minerals

• Concern over 4 strategic metal resources 1. Manganese 2. Cobalt 3. Chromium 4. Platinum

— these are essential for the country’s economy and military strength… little in U.S.

Supplies of nonrenewable mineral resources can be economically depleted • The future supply of nonrenewable

minerals depends on two factors: 1. The actual or potential supply of the mineral. 2. The rate at which we use it. – Minerals may become economically depleted

when it costs more than it is worth to find, extract, transport, and process the remaining deposits. Options when this occurs are: • Recycle or reuse existing supplies. • Waste less or use less. • Find a substitute or do without.

Market prices affect supplies of nonrenewable minerals

• What are the economic issues related to mining?

Can we get more of our minerals from the oceans?

• Issues involved with this approach?

HOW CAN WE USE MINERAL RESOURCES MORE SUSTAINABLY?

Section 12-5

We can use nonrenewable mineral resources more sustainably

Three big ideas • Dynamic forces move matter, recycle the earth’s rocks,

form deposits of mineral resources, and cause volcanic eruptions, earthquakes, and tsunamis.

• Mineral availability depends on quantity in the earth’s crust, rate of use, mining technology, market prices, and the harmful environmental effects of removing/using it.

• We can use mineral resources more sustainably by

trying to… find substitutes for scarce resources, reducing waste, and reusing and recycling nonrenewable minerals.

The End

Material beyond this point is supplemental!

The earth beneath your feet is moving

• The forces produced at these plate boundaries can cause earthquakes, erupting volcanoes and mountains to form.

• Oceanic plates move apart from one another allowing magma, to flow up between them.

• Much of the geologic activity at earth’s surface takes place at the boundaries between tectonic plates as they move in the resulting cracks. – Oceanic ridges may have peaks higher and

canyons deeper than those found on the earth’s continents.

The earth beneath your feet is moving

– When two oceanic plates collide, a trench ordinarily forms at the boundary between the two plates.

– When an oceanic plate collides with a continental plate, the continental plate usually rides up over the denser oceanic plate and pushes it down into the mantle in a process called subduction.

– The area where this collision and subduction takes place is called a subduction zone.

– Tectonic plates can also slide and grind past one another along a fracture (fault) in the lithosphere—a type of boundary called a transform fault.

Volcanoes release molten rock from the earth’s interior

• An active volcano occurs where magma reaches the earth’s surface through a central vent or a long crack, called a fissure.

• Many volcanoes form along the boundaries of the earth’s tectonic plates when one plate slides under or moves away from another plate.

• Magma that reaches earth’s surface is called lava. • Volcanic activity can release large chunks of lava

rock, glowing hot ash, liquid lava, and gases into the environment.

Earthquakes are geological rock-and-roll events

• Forces inside the earth’s mantle and near its surface push, deform, and stress rocks.

• The stress can cause the rocks to suddenly shift or break and produce a transform fault, or fracture in the earth’s crust.

• When a fault forms or when there is abrupt movement on an existing fault, energy that has accumulated over time is released in the form of vibrations, called seismic waves, causing an earthquake.

Earthquakes are geological rock-and-roll events

• The severity of an earthquake is measured by the magnitude of its seismic waves.

• The magnitude is a measure of shaking caused by the earthquake, as indicated by the size of the seismic waves when they reach a seismograph.

• Scientists use the Richter scale, on which each unit has amplitude 10 times greater than the next smaller unit.

Earthquakes on the ocean floor can cause huge waves called tsunamis • A tsunami is a series of large waves generated

when part of the ocean floor suddenly rises or drops.

• Most large tsunamis are caused when certain types of faults in the ocean floor move up or down as a result of a large underwater earthquake, a landslide caused by such an earthquake, or in some cases by a volcanic eruption.

• Tsunamis are often called tidal waves, although they have nothing to do with tides.

Earthquakes on the ocean floor can cause huge waves called tsunamis • They can travel far across the ocean at the

speed of a jet plane. • In deep water the waves are very far apart—

sometimes hundreds of kilometers—and their crests are not very high.

• As a tsunami approaches a coast, it slows down, its wave crests squeeze closer together, and their heights grow rapidly.

• Hits a coast as a series of towering walls of water that can level buildings.

Earthquakes & Tsunami impacts on the ocean floor can cause huge

waves called tsunamis • Tsunamis can be detected through a network of

ocean buoys or pressure recorders located on the ocean floor to provide some degree of early warning sent through emergency warning centers. – Between 1900 and 2010, tsunamis killed an estimated

280,000 people along the Pacific Ocean. – The largest loss of life (279,900) occurred in December

2004 when a great underwater earthquake in the Indian Ocean with a magnitude of 9.15 caused a tsunami that generated waves as high as a five-story building.

Earthquakes are geological rock-and-roll events

• One way to reduce the loss of life and property damage is to examine historical records and make geologic measurements to locate active fault zones. – Map high-risk areas and establish building codes

that regulate the placement and design of buildings in such areas.

– People evaluate the risk and factor it into their decisions about where to live.

– Engineers know how to make buildings and structures more earthquake resistant.

Earth’s rocks are recycled very slowly

• The rock cycle is the interaction of physical and/or chemical processes that change rock from one form to another.

• It takes millions of years for this cycle to happen.

There are several ways to remove mineral deposits

• Shallow mineral deposits are removed by surface mining by: – Removing vegetation. – Removing the overburden or soil and rock

overlying a useful mineral deposit. – Placing waste material set aside in piles,

called spoils. • Open-pit mining.

There are several ways to remove mineral deposits

• Strip mining is useful and economical for extracting mineral deposits that lie in large horizontal beds close to the earth’s surface. – Area strip mining is used where the terrain is

fairly flat; a gigantic earthmover strips away the overburden, and a power shovel removes the mineral deposit.

– Contour strip mining is used mostly to mine coal on hilly or mountainous terrain.

There are several ways to remove mineral deposits

• Mountaintop removal uses explosives, large power shovels, and huge machines called draglines to remove the top of a mountain and expose seams of coal.

• Subsurface mining removes minerals from underground through tunnels and shafts.

Some environmental impacts of mineral use

• Metals can be used to produce many products. • Life cycle of a metal—mining, processing, and

using it—takes enormous amounts of energy and water and can disturb the land, erode soil, produce solid waste, and pollute the air, water, and soil.

• The more accessible and higher-grade ores are usually exploited first.

• As they are depleted, mining lower-grade ores takes more money, energy, water, and other materials, and increases land disruption, mining waste, and pollution.

Mining has harmful environmental effects

• Scarring and disruption of the land surface. – Mountaintop removal destroys forests, buries

mountain streams, and increases flood hazards. Wastewater and toxic sludge, produced when the coal is processed, are often stored behind dams in these valleys, which can overflow or collapse and release toxic substances such as arsenic and mercury.

Mining has harmful environmental effects

– In the United States, more than 500 mountaintops have been removed to extract coal and the resulting spoils have buried more than 1,100 kilometers (700 miles) of stream.

– Surface mining in tropical forests and other tropical areas destroys or degrades vital biodiversity when forests are cleared and rivers are polluted with mining wastes.

– Produces toxic waste material such as lead dust, which can cause lead poisoning and irreversible brain damage in children.

Mining has harmful environmental effects

• Subsurface mining disturbs less land than surface mining disturbs, and it usually produces less waste material. – Creates hazards such as cave-ins, explosions,

and fires. – Miners often get diseases such as black lung,

caused by prolonged inhalation of coal dust in subsurface mines.

– Causes subsidence—the collapse of land above some underground mines.

Mining has harmful environmental effects

• Mining operations produce large amounts of solid waste and cause major water and air pollution. – Acid mine drainage occurs when rainwater that seeps

through a mine or a spoils pile carries sulfuric acid to nearby streams and groundwater.

– Mining has polluted about 40% of western watersheds in the United States, and it accounts for 50% of all the country’s emissions of toxic chemicals into the atmosphere.

– Much of this degradation comes from leaking storage ponds built to hold a toxic sludge that is produced from the mining and processing of metal ores.

Is mining lower-grade ores the answer?

• Extraction of lower grades of ore is possible due to new earth-moving equipment, improved techniques for removing impurities from ores, and other technological advances in mineral extraction and processing.

• Mining low-grade ores is limited by: – Increased cost of mining and processing

larger volumes of ore.

Is mining lower-grade ores the answer?

– Increasing shortages of freshwater—which is needed to mine and process some minerals—especially in arid and semiarid areas.

– Environmental impacts of the increased land disruption, waste material, and pollution produced during mining and processing.

• Can use microorganisms that can break down rock material and extract minerals in a process called in-place, or in situ, mining or biomining.

We can find substitutes for some scarce mineral resources

• Human ingenuity will find substitutes. • Current materials revolution in which

silicon and other new materials, particularly ceramics and plastics, are being used as replacements for metals.

• Finding substitutes for scarce minerals through nanotechnology.

We can recycle and reuse valuable metals

• A more sustainable way to use nonrenewable mineral resources (especially valuable or scarce metals such as gold, copper, and aluminum) is to recycle or reuse them.

• Recycling has a much lower environmental impact than mining and processing ores.

• Cleaning up and reusing items instead of melting and reprocessing them has an even lower environmental impact.

We can use mineral resources more sustainably

• Instead of asking how we can increase supplies of nonrenewable minerals, we should be asking, how can we decrease our use and waste of such resources?

• Since 1990, a growing number of companies have adopted pollution and waste prevention programs that have led to cleaner production.