We use things the Earth gives us to help us live

better lives

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UGRC 143 : SCIENCE AND TECHNOLOGY IN OUR

LIVES

SECOND SEMESTER : 2014/2015 ACADEMIC YEAR

EARTH RESOURCES

Dr. Larry Pax ChegbelehDepartment of Earth ScienceUniversity of Ghana, Legon

Purpose and Objectives of lesson

Introduction

Resources

Earth resources

Resources management

The rock cycle, formation and classification

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This lesson is to enable you understand what resources are and how to manage them for sustainable livelihood

It is expected that by the end of the lesson you should be able to …..

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Define resources in general and earth

resources in particular

Identify various categories of resources

Differentiate between resources and

reserves

Define the types of rocks

Explain the formation of the rock types

State the major classifications of rocks

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To some extend you have

prior knowledge of what

resources are

More understanding is

required to know their

differences5

All those things that are necessary or

important to human life and civilization

A source or supply from which benefit is

derived or produced

Any material that can be transformed to

produce benefit

Typical examples include: Materials

Knowledge

Staff (Human resources) skills, energy, talent

and knowledge used for the production of

goods or rendering of services

Services

Energy

Other things that are transformed to produce

benefit

The benefit derived can be utilized/consumed

or made unavailable in the process

Some of the benefits of using resources

include:

Increase in wealth

Meeting our needs

Proper functioning of a system

Enhancing well being

We use resources to make things and to

grow things we need

Examples of things we use include:

Water to drink and grow plants for food,

shelter, and clothing.

Soil to grow plants for food, shelter, and

clothing.

Rocks for building and jewelry.

Metals to make cans, building parts, and

jewelry.

Sand to make glass.

Oil to make plastics and gasoline.

Resources that are involved in or formed by

geologic processes

From human point of view is anything

obtained from the environment to satisfy

human needs

From ecological or biological view point is

anything that satisfies the needs of living

organisms

Examples of earth resources include

Groundwater

Soil

Rocks

Minerals

Oil and gas

Earth resources are classified into various

categories based on:

Source of origin

Stage of development

Renewability or replenishment

Based on origin, resources may categorized

into:

Biotic: - these are obtained from the

biosphere (living and organic material)

▪ Examples: forests and animals and

materials that can be obtained from

them

▪ Coal and petroleum are formed from

decayed organic materials

Abiotic: - these are those that come from

non-living and non-organic materials

▪ Examples include: air, fresh water, land,

minerals

Based on stage of development, resources may

categorized into:

Potential resources: - these are those that

exist in an area or region and are

recoverable in the future

▪ Example: petroleum may occur in various

regions, until it is actually drilled out,

developed and put into use, it remains a

potential resource

Actual resources: - these are those that that

have been investigated and quantified and

being used in present times

Reserved resources: the part of an actual

resource that can be developed profitably

with available technology

Stock resources: those that have been

investigated but can not be put to use due

to lack of technology

Based on the time required to replace the

quantity of resources used (renewability) or

consumed, resources can be

Renewable

Nonrenewable

Inexhaustible (Perpetual resources)

Renewable Resources

Resources that can be replenished over fairly

short spans of time, such as months, years, or

decades (e.g., trees)

Can be replenished naturally

From human perspective, rate of replenishment

or recovery exceeds that of consumption

Can be depleted by human consumption

Nonrenewable Resources

Rate of consumption exceeds rate of

replenishment or recovery (time needed to

create >>> time needed to consume).

Form slowly or do not naturally form in the

environment (may take millions of years to

form and accumulate)

E.g. fossil fuels (petroleum)

Inexhaustible Resources

These are available continuously

Their quantity is not affected by human consumption

We shall never run out, like sunlight, air, and wind

However it can be ruined by pollution.

Resources may also be categorized based on

distribution

Ubiquitous resources: these are found

everywhere in the world (e.g. air, light and

water)

Localized resources: these are found in

certain parts of the world or within certain

localities (e.g. Iron ore, copper ore and

geothermal power)

Exceptions

All earth resources, except

groundwater, are nonrenewable

The more people on earth

oThe more water we consume

oThe more food we grow/eat

oThe more fuel we burn

oThe more minerals we use

Rates of resources used even

increasing faster than rate of

population increase.

Why?

o Elevated standards of living.

o improvements in life-styles hence,

increasing quantities of

manufactured goods ( cars, clothes,

computers, etc.)

In order to make resources last,

we must take good care of them

Use resources sustainably

Population

Population of the planet is growing

rapidly

Use of minerals/energy has climbed

more rapidly than the overall growth

of population

REDUCE: How much we use

REUSE: What we can

RECYCLE: Whatever we can

In order to help our Earth to keep

providing for our needs.

3Rs of Resource Management

The biotic and abiotic surrounding

of an organism including factors that

have influence in the survival,

development and evolution of the

organisms

Environment (biophysical environment)

Implies surrounds and influences

organisms.

Physical environment encompasses

water, air, soil and rock.

Environment (biophysical environment)

Marine environment

(oceans, e.g. water bodies)

Atmospheric environment

(Layer of gases surrounding the earth, e.g. nitrogen and

oxygen)

Terrestrial environment

(Land, e.g. soil and rock)

Biophysical Environment Subdivision

Number of biophysical environment

is myriad if we consider that each

living organism has its own

environment

The harmful aspect of human

activities on the biophysical

environment.

The term anthropogenic is used to

designate an effect or object resulting

from human activity

Local, regional, and global

Caused by people and societies

Urban air pollution

Acid rain

Ozone depletion

Acid mine drainage

Global warming

Resources are not the same as Reserves

Reserves are measured (proven)

economic resources (e.g. barrels of

crude oil or tons of chromium ore)

Look at this graphically:

Reduce

Reuse

Recycle

Save our Natural Resources!

A rock is any solid mass of

minerals or mineral-like matter

occurring naturally as part of

our planet

A rock is simply an aggregate of

minerals

Types of Rocks

Igneous rock is formed by the

crystallization of molten magma.

Types of Rocks

Metamorphic rock is formed by the

alteration of pre-existing rock deep

within Earth (but still in the solid state)

by heat, pressure, and/or chemically

active fluids.

Types of Rocks

Sedimentary rock is formed from

the weathered products of pre-existing

rocks that have been transported,

deposited, compacted, and cemented.

Important terms to note

Magma is molten material that is

formed deep beneath the Earth’s surface.

Lava is magma that reaches the surface.

Weathering is a process in which rocks

are broken down by water, air, and

living things.

Sediment is weathered pieces of Earth

elements.

Shows the

interrelationships among

the three rock types

(igneous, sedimentary,

and metamorphic)

Processes driven by heat from the Earth’s

interior are responsible for forming both

igneous rock and metamorphic rock.

Weathering and the movement of weathered

materials are external processes powered by

energy from the sun.

External processes produce sedimentary

rocks.

1. Intrusive igneous rocks are formed

when magma hardens beneath Earth’s

surface.

2. Extrusive igneous rocks are formed

when lava hardens.

Igneous rocks can be classified based on

their

Texture

Chemical composition

Texture

Coarse-grained texture: Caused by slow

cooling resulting in larger crystals.

Fine-grained texture: Caused by rapid cooling

resulting in smaller, interconnected mineral

grains.

Texture

Glassy texture: Caused by very rapid cooling.

Porphyritic: Caused by differential rates of

cooling resulting in varied sized mineral grains.

Chemical composition

Granitic: Made mostly of light-colored quartz and

feldspar.

Andesitic: Between granitic light-color minerals

and basaltic composition dark-colored minerals.

Chemical composition

Basaltic: Mostly of dark-colored silicate

minerals and plagioclase feldspar.

Ultramafic: Made mostly from iron and

magnesium-rich minerals.

Erosion involves the weathering and the

removal of rock.

Deposition occurs when an agent of erosion

such as water, wind, ice, or gravity loses

energy and drops sediments.

Weathering, Erosion, and Deposition

Compaction is a process that squeezes, or

compacts sediments.

Cementation takes place when dissolved

minerals are deposited in the tiny spaces

among the sediments.

Compaction and Cementation

1. Clastic sedimentary rocks are composed

of weathered bits of rocks and minerals.

• Classified by particle size

Two Main Groups

- Shale (most abundant)

• Common rocks include

- Conglomerate

- Sandstone

Two Main Groups2. Chemical sedimentary rocks form when dissolved

substances precipitate, or separate, from water.

• Common rocks include

- limestone—most abundant chemical rock

- microcrystalline quartz known as chert, flint,

jasper, or agate

- evaporites such as rock salt or gypsum

- coal

Metamorphism means “to change

form”

Most metamorphic changes occur at

elevated temperatures and pressures

Conditions for formation - a few

kilometers below the Earth’s surface and

extend into the upper mantle

Contact metamorphism

Regional metamorphism

Contact metamorphism

Occurs when magma moves into rock.

Occurs near a body of magma

Changes are driven by a rise in

temperature

Regional metamorphism

Results in large-scale deformation and

high-grade metamorphism

Directed pressures and high temperatures

occur during mountain building

Produces the greatest volume of

metamorphic rock

• .

Heat

Pressure

Hydrothermal Solutions

Heat Provides the energy needed

to drive chemical reactions

Pressure Causes a more compact

rock with greater density

Hydrothermal Solutions

Hot water-based solutions escaping

from the mass of magma

Promote recrystallization by

dissolving original minerals and

then depositing new ones

1. Foliated Metamorphic Rock

o Has a banded or layered appearance

2. Nonfoliated Metamorphic Rock

o Does not have a banded texture

Two main categories