lecture notes for week 3

Our Earth’s Resources

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

OVERVIEW

Purpose and Objectives of lesson Introduction Resources Earth resources Resources management The rock cycle, formation and

classification2

Purpose and Objectives

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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Purpose and Objectives

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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Introduction

To some extend you have prior knowledge of what resources are

More understanding is required to know their differences

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What are Resources?

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

What are Resources? 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

What are Resources? 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

How we use them 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.

How we use them

Metals to make cans, building parts, and jewelry.

Sand to make glass. Oil to make plastics and gasoline.

Earth or Natural Resources 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

Earth or Natural ResourcesExamples of earth resources include

Groundwater Soil Rocks Minerals Oil and gas

Classification of Earth or Natural Resources

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 beRenewableNonrenewableInexhaustible (Perpetual resources)

Renewable ResourcesResources that can be replenished over fairly

short spans of time, such as months, years, or decades (e.g., trees)

Can be replenished naturallyFrom human perspective, rate of replenishment

or recovery exceeds that of consumptionCan 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 ResourcesThese 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)

ExceptionsAll earth resources, except groundwater, are nonrenewable

Resources, People and standards of living

The more people on earthoThe more water we consumeoThe 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.)

Resources management

In order to make resources last, we must take good care of them

Use resources sustainably

Earth System Science

Population

Population of the planet is growing rapidly

Use of minerals/energy has climbed more rapidly than the overall growth of population

Growth of World Population

REDUCE: How much we useREUSE: What we canRECYCLE: Whatever we can

In order to help our Earth to keep providing for our needs.

3Rs of Resource Management

Use Resources Wisely to Protect our Environment

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)

Use Resources Wisely to Protect our 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

Environmental Problems

Environmental Problems

Local, regional, and global Caused by people and societies

Urban air pollutionAcid rainOzone depletionAcid mine drainageGlobal warming

Urban air pollution

Acid rain

Ozone depletion

Acid mine drainage

Effects of Global Warming

Resources Vs. Reserves

Resources are not the same as ReservesReserves are measured (proven)

economic resources (e.g. barrels of crude oil or tons of chromium ore)

Look at this graphically:

Resources vs. Reserves

Examples of resources

Copper and aluminum

Sand and Limestone

Salt and Silver

Clay and coal

REMEMBER TO:

ReduceReuseRecycle

Save our Natural Resources!

What is a rock?

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

What is a rock?

Types of Rocks

Igneous rock is formed by the crystallization of molten magma.

What is a rock?

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.

What is a rock?

Types of Rocks

Sedimentary rock is formed from the weathered products of pre-existing rocks that have been transported, deposited, compacted, and cemented.

What is a rock?

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.

The Rock Cycle

Shows the interrelationships among

the three rock types (igneous, sedimentary, and metamorphic)

Energy That Drives the Rock Cycle

Processes driven by heat from the Earth’s interior are responsible for forming both igneous rock and metamorphic rock.

Energy That Drives the Rock Cycle

Weathering and the movement of weathered materials are external processes powered by energy from the sun.

External processes produce sedimentary rocks.

Formation of Igneous Rocks

1. Intrusive igneous rocks are formed when magma hardens beneath Earth’s surface.

2. Extrusive igneous rocks are formed when lava hardens.

Classification of Igneous Rocks Igneous rocks can be classified based on

their

TextureChemical composition

Classification of Igneous Rocks

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.

Course-Grained Igneous Texture

Fine-Grained Igneous Texture

Obsidian Exhibits a Glassy Texture.

Porphyritic Igneous Texture


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.

Basalt

Formation of Sedimentary Rocks

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

Formation of Sedimentary Rocks

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

Classification of Sedimentary Rocks

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

Shale with Plant Fossils

Conglomerate


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

Fossiliferous Limestone

Formation of Metamorphic Rocks

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 metamorphismRegional metamorphism


Contact metamorphismOccurs when magma moves into rock. Occurs near a body of magmaChanges are driven by a rise in

temperature

Metamorphic Rocks

Regional metamorphism Results in large-scale deformation and

high-grade metamorphismDirected pressures and high temperatures

occur during mountain buildingProduces the greatest volume of

metamorphic rock

• .

Agents of Metamorphism

Heat Pressure Hydrothermal Solutions


Heat Provides the energy needed

to drive chemical reactions


Pressure Causes a more compact

rock with greater density

Origin of Pressure in Metamorphism


Hydrothermal Solutions Hot water-based solutions escaping

from the mass of magma Promote recrystallization by

dissolving original minerals and then depositing new ones

Classification of Metamorphic Rocks

1. Foliated Metamorphic Rocko Has a banded or layered appearance

2. Nonfoliated Metamorphic Rocko Does not have a banded texture

Two main categories

Classification of Metamorphic Rocks

Gneiss Typically Displays a Banded Appearance

Marble—A Nonfoliated Metamorphic Rock

End of Lesson 2

lecture notes for week 3

Documents

earths resources

objectivesdefine resources

classification of earth

themwe use resources

natural resourcesresources

examples of things

natural resourcesbased

natural resourcesabiotic