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Our Earth
Grades 6-9
OUR EARTH
INTRODUCTORY EARTH SCIENCE
INTRODUCTION
Presented by young scientists, this seven-part series explores Earth science topics,
including the age of the Earth, fossils, composition of the inner Earth,
plate tectonics, forces that change the Earth’s surface, types of rocks,
and the importance of geology.
2
HOW OLD IS IT?
Geology as a science began with the Industrial Revolution in England. Rock strata were studied and compared and an amazing
conclusion was drawn. Students will learn that our Earth is unbelievably old.
9. The oldest fossils known are thought to be 3700 million
years old. What are they?
Objectives To discuss how the study of geology was started and why it
was started.
10. How old is the Earth?
Lesson Summary -
Discussion Answers -
Geology as a science began with the Industrial Revolution in
England when rock strata were studied and compared.
1. Miners noticed that many rocks were in layers, or strata,
piled one on top of the other.
Vocabulary List -
2. The popular explanation for extinct species was that they
were all wiped out by a great flood or similar catastrophe.
geology strata
period
geologist
era
Industrial Revolution
Discussion Questions 1. The first clues to the Earth’s age came when miners
noticed something about the rocks below the surface. What
did they notice?
2. When people found fossils of extinct life forms—what
was the popular explanation of why the life forms had
disappeared?
3. What evidence was there to show that the popular
explanation was not good enough?
4. a. T or F: Sedimentation is the result of moving material
from low places to high places.
b. T or F: Sedimentation is not the only way a rock is
created.
5. What was the name of the scientist who published a
famous book about how geological processes work?
6. What was the main message of the book?
7. By the end of the 19th century, despite knowing a lot
about the events in Earth’s history, scientists still didn’t
know how old Earth is. What was discovered early in the
20th century that gave them the clues they needed?
8. How long ago did dinosaurs come to an end?
3. There were many strata, and many had their own separate
collection of life forms, suggesting that there were many
floods. In fact, the wide spread of similar strata suggested
floods over immense areas. But sedimentation was also
shown to be a very slow process, taking a very long time to
build up, with many breaks and changes in the process.
Flooding was certainly part of the explanation, but the
evidence in the strata was that a huge number of events
happened over an enormous period of time.
4. a. false b. true
.
5. Charles Lyell. The book was called PRINCIPLES OF
GEOLOGY.
6. He proposed that the geological change on Earth was
happening today in the same way as it had happened in the
past and that most changes are slow and gradual. This is
called “uniformitarianism.” In his day it was held out as an
alternative catastrophe. Today we accept that geological
change happens in both ways, but Lyell’s central idea—that
Earth’s geology is happening today is the same.
7. They discovered radioactive minerals. Radioactive dating
has given actual events of Earth’s history.
8. The dinosaurs became extinct 65 million years ago.
9. The oldest fossils presently known are of bacteria.
10. Earth is circa 4.6 billion years old.
3
FOSSILS
A fossil is a trace of a living thing left in a rock. Fossils offer a three-part challenge. First is to reconstruct the organism itself, then
to reconstruct the world it lived in, then to understand its place in time and evolution.
10. Paleontologists are scientists trying to understand fossils
at three levels:
a. to reconstruct the creature itself
b. to understand its world and
c. What?
Objectives 1. To define fossil
2. To explain the importance of fossils
Lesson Summary -
Discussions Answers A fossil is a trace of a living thing left in rock. Fossils offer a
three-part challenge. First challenge is to reconstruct the
organism itself, then reconstruct the environment in which it
lived and finally try to understand its place in time and
evolution.
Vocabulary List fossil
extinct
paleozoology
paleobotany
era
period
sedimentary
Discussion Questions 1. What is a fossil?
2. a. Trilobites are ancient relatives of crabs, lobsters
and...what else?
b. The world of the trilobites began in...what geological
period?
3. In fossils, we sometimes find that a mineral has replaced
the original material and made a perfect copy. Where does
this mineral come from?
4. Name two factors about an organism, which raises the
chances of it becoming a fossil.
1. A fossil is a trace of a living thing preserved in rock.
2. a. Trilobites are also ancient relatives of insects.
b. The world of Trilobites began in the Cambodian period.
3. The mineral that may replace an original fossil is
dissolved in the water in the sediment and is often the same
mineral that has helped cement the sediment grains into rock
in the first place.
4. Fossils are more likely to be found when:
a. the organism was very numerous
b. lived recently
c. had hard parts
d. lived in water or
e. lived on the bottom
5. Some clues to the world of Trilobites are: a. they are
similar to crabs and shrimps so we can assume they lived in
the same way; b. many had complex eyes, sensitive to
movement, so maybe they were on the lookout for other
creatures, and they probably lived in well lit waters; c. some
were found rolled into a defensive ball, so they probably had
to defend themselves against predators; d. fossils of other
creatures of the same time give us a glimpse of their
neighbors (ex.: swimming creature with powerful jaws).
5. Name two clues that help us picture the world of the
trilobites.
6. Trace fossils
6. Fossils which are just marks that living things have made
(like footprints) are called...what?
7. In undisturbed strata the oldest rocks are always found at
the bottom.
7. In undisturbed strata the oldest rocks are always
found...where?
8. (Oldest to youngest) Stromatolites, trilobites, fish,
dinosaurs, humans
8. Put the following into the order in which they appear on
the geological timetable:
dinosaurs
stromatolites
humans
fish
trilobites
9. A large asteroid, which struck the Earth 65 million years
ago, was very likely the cause of a massive extinction at that
time, wiping out the dinosaurs.
9. The presenter says, “The disaster that we think finished
the dinosaurs was…?”
10. The third level of understanding is to fit the fossil into a
picture of time and evolution. That means fitting it into the
geological timescale and classifying it into the tree of life.
4
THE FIRES BELOW
The interior of the Earth is very hot. Clues lead us to believe there is a metallic core surrounded by a rocky mantle. Huge, slow
convection currents rise up, often resulting in earthquakes and volcanoes.
7. If a volcano is being fed by melted crustal rocks it can be
very dangerous. Why?
Objectives To explain the construction of the Earth and how this
construction may cause geologic activities such as
volcanoes, earthquakes, etc.
8. Molten rock above ground is called lava. But molten rock
below ground is called…?
Lesson Summary -
9. Why is the ancient Roman city of Pompeii famous?
Whatever is inside the Earth is very hot. Study has led us to
believe that the center of the Earth is a metallic core
surrounded by a rocky mantle. The heat from the center
generates convection currents which causes molten lava to
circulate and sometimes come to the surface via volcanoes.
This movement can also cause earthquakes.
10. The Earth has had over 4 billion years to cool down, but
it still seems very hot inside. What could add to its heat?
Vocabulary List core
heavy metal
lava
dike
convection
dome
sill
fault
basalt
mantle
igneous volcanoes
syncline anticline
Discussions Answers 1. We can study the rocks that come out of volcanoes or
Seismic waves can travel through the Earth and give clues to
what lies deep within.
2. The enormous pressure of the miles of rocks above forces
it to stay solid. If it comes closer to the surface where the
pressure is less, it tends to melt.
3. a. the crust; b. the mantle; c. the core
Discussion Questions 1. What is one way we can use to study rocks that lie deep
underground?
2. Lava out of volcanoes proves that rock underground gets
hot enough to melt. But deep underground it stays solid, like
red-hot steel. What keeps it from melting?
4. Iron is magnetic and the Earth has a planet-sized magnetic
field or iron is a lot heavier than rock and we calculate the
Earth is too heavy to be made of all rock.
5. c. liquid outer-inner solid
6. False. As rock gets hotter, the less dense it becomes, so it
tends to rise through other, less hot rock.
3. Name the three main layers inside the Earth?
4. We think the middle of the Earth is mostly iron. Give one
reason why.
5. The middle of the Earth is what a. all liquid,
b. all solid, c. liquid outer - solid, inner,
d. solid outer - liquid inner.
6. T or F. Supper hot rock is heavier than cooler rock, so it
tends to sink?
7. Melted crushed rocks often contain water, water vapor,
and other gases. Steam and these gases can build up huge
pressure, causing dangerous explosions.
8. Magna is melted rock still underground.
9. Pompeii is famous because in 79 AD it was completely
buried, when the so-called “dead” volcano, Mount Vesuvius
erupted.
10. Radioactivity could be adding heat inside the Earth, but
we don’t know exactly how much.
5
PUSHING AND SHOVING
In this program tectonic forces and their end products are discussed. Students will learn how these forces shape the Earth as we
know it.
Objectives To introduce and explain tectonic forces and their role in
continental drift.
8. Most earthquakes in Australia are small, but some can still
be dangerous. Why?
Lesson Summary -
9. Rather than break as a fault, rocks can bend and fold when
the pressure increases very slowly and/or the rock is ... what
else?
Tectonic forces are the forces constantly pushing at
continents and rock layers and cause earthquakes, and
continental drift, the movement of continents.
Discussion Answers 1. The ancient super-continent was called Pangaea.
Vocabulary list 2. Convection
tectonic plates
thrust faults
continents
earthquakes
faults
continental drift
Discussion Questions 1. What is the name given to the ancient super-continent
from which the present continents have split?
2. Super-hot rock in the mantle moves slowly is a circular
motion. What is the name given to this heat driven motion?
3. When a plume of super-hot rock pushes up through the
mantle. it forces the cooler rock aside. What effect does this
have on the crust above?
4. When a continent on the edge of a tectonic plate is forced
against a sea floor on the edge of another plate, the sea floor
is always the loser. It returns to the mantle. Why?
5. What example is shown in the program as evidence that
continents have stayed on top of the mantle for most of
Earth’s history?
6. New Zealand is tectonically active, with volcanoes, hot
springs and mountain building. But very little of this is
happening in Australia. Why?
7. T or F. Australia was built from east to west over a period
of some 4 billion years.
3. At the top of a plume of super-hot rock in the mantle the
sideways spreading motion pulls the crust apart. This results
in magma emerging at a mid-ocean rift valley and this newly
made sea floor slowly spreads outwards on either side.
4. The sea floor always returns to the mantle because its
rocks are denser and heavier than the rocks of the continents.
The lighter granite rocks of the continent tends to rise over
the more dense basaltic rocks of the sea floor.
5. We showed some rocks in a railway cutting in Western
Australia, which are 2700 million years old. Since the Earth
itself is counted as 4600 million years old, that shows that
these rocks have avoided being remelted for over half the
Earth’s history.
6. Most tectonic action happens at plate edges. Unlike New
Zealand, Australia sits well inside the edges of its plate,
away from the action.
7. False
8. True
9. Although they are usually small, most earthquakes in
Australia are shallow and near the surface. That means they
can be near to us, and therefore, dangerous...and/or when the
rock is hot, e.g., when it is at great depth.
6
WEAR AND TEAR
The forces of the sun, wind and water change the face of the Earth. Students will learn about erosion, the freeze-thaw cycle and
other forces that cause wear and tear on the Earth.
9. T or F: The bottom of an estuary is gravely because all the
light sand and sediment has been washed away.
Objectives To introduce and explain the various natural forms of
erosion and their outcomes.
10. Why do mountains still exist, when millions of years of
erosion should have worn them flat?
Lesson Summary Discussions Answers This lesson deals with the natural forces on the face of the
plane—wind, water, and sun, that change the earth’s surface
as it attempts to form a peneplain. Different types of erosion
are studied.
Vocabulary List erosion
wind erosion
water erosion
peneplain
Discussion Questions 1. We would not be here and Earth would be a rocky and
hostile planet if geological wear and tear did not produce...
What?
1. Soil
2. Weathering
3. Any two of the following:
a. Chemical weathering – oxidation; dissolution by
acids (water becomes acidic by picking up plant
acid, acid from industrial pollution, from
volcanoes).
b. Physical weathering – Heating and cooling, plants
roots crack rocks, water freezing in rocks, release of
subterranean pressures.
4. Regolith
2. What is the first stage of this wear and tear called?
3. In the program we describe six ways rocks are destroyed
by this first stage of wear and tear. Name two of them.
5. Soil is generally defined as crumbled rock material
(regolith) that is capable of growing plants
6. Gravity drives erosion.
4. Crumbled rock material has an overall name. What is it?
5. The word “soil” is generally used to indicate crumbled
rock material that has a particular quality. What is that?
7. The scars indicate that ice was once much more
widespread—in the Ice Ages.
8. Water as a liquid is the major agent of erosion.
6. What drives erosion?
9. False
7. Horizontal scars on rock can be found thousands of miles
away from glaciers. What does that indicate?
8. Ice may be the powerful agent of erosion, but what agent
has actually carved most rock and moved most soil on
Earth?
10. New land and mountains are uplifted by tectonic activity.
Amazingly, erosion itself is responsible for some uplift too,
because as material is removed from the high places their
weight is reduced. They may float up higher on the rocks of
the mantle below.
7
ROCK RECIPES
Igneous, sedimentary and metamorphic rocks are discussed.
Objectives -
8. Name one kind of metamorphic rock.
To introduce and explain the three types of rocks and how
they are formed.
9. Only one kind of rock can possibly contain fossils. Which
one?
Lesson Summary -
10. What does the rock cycle show?
Rocks are complicated collections of mineral particles but
are classified into one of three types based on the way there
were formed—sedimentary, igneous, and metamorphic.
Different samples of each are shown and discussed including
the way they were formed and their importance in the study
of geology.
Discussion Answers 1. A mineral is also of uniform chemical composition. (Here
we are giving a basic definition. Minerals can be found with
compositional zoning, a fact that belies this definition
somewhat. But the general principle of having a purity that
can form crystals is the idea.)
Vocabulary List sedimentary
sediment
fossils
basalt
lava
igneous
minerals
lava flow
metamorphic
Discussion Questions 1. To be a mineral a substance must be natural, it must be a
solid and...what else?
2. To form a crystal it helps if a substance starts out as a
liquid or is dissolved in a liquid. Why?
2. In liquids atoms can move relatively easily, allowing them
to assemble themselves in perfect order.
3. Mafic materials, micas, feldspars, quartz
4. They may be made of the same basic molecules (silicate)
but these molecules are assembled in different ways. We
showed a model of a chain silicate (the mafic mineral) and a
framework silicate (quartz—with feldspars as alternate
framework silicates containing some aluminum) and mica is
a sheet silicate.
5. Plutons
3. The presenter shows examples of four groups of common
minerals which, mixed together, make up 90 percent of the
rocks on the Earth’s crust. Name two of these minerals.
4. If the four groups of common minerals are all silicates,
why do they look different and have different properties?
5. Bodies of igneous rocks that have cooled and solidified
deep underground, and have finally emerged on the surface
are called ____?
6. False
7. There are many sedimentary rocks. We showed
conglomerate, sandstone, shale, and limestone.
8. There are many metamorphic rocks. We showed marble,
slate, and gneiss.
9. Only sedimentary rocks are made gentle enough to
preserve fossils.
6. T or F: Fast cooling means big crystals.
7. Name one kind of sedimentary rock.
10. The rock cycle shows how rocks are constantly changing
from one form to another.
8
WHO NEEDS GEOLOGY?
The program discusses the importance of geology and why we need to understand many of its basic findings.
Objectives 9. One area in which geology still has a lot to learn is____?
To discuss some of the reasons why the study of geology is
important to our way of life.
10. When the presenter says that geology helps him to see in
another dimension...what dimension is that?
Lesson Summary Discussion Answers Every culture has wondered about the origin of the Earth and
geology offers a rich and cautionary explanation and look
into the past. Geology is also important because practically
all our energy sources and most of our products are derived
from the ground and geology helps us find and exploit these
energy sources.
Vocabulary List culture
energy
kinetic
potential
1. Deeper down, the heat and pressure would never permit a
cave to exist. It would be crushed together.
2. Satellite images, gravimeter, magnetometer, seismic
profile, rock hammer, geology map.
3. Iron in the body and engine, aluminum in the body and
engine, lead in the battery, titanium in the paint, tungsten in
the lights (filaments), glass in the windshield, ceramics in
the brakes, polymers and plastics in the seats and trim.
Discussion Questions 4. Aluminum. It is extracted from bauxite.
1. It’s not possible for a cave to go all the way to the center
of the Earth. Why?
2. Name two things that geologists use to get clues to what’s
underground (other than digging or drilling).
5. Concrete
6. Ancient air bubbles in ice and some fossils can give clues
to the weather of the past—and thus to what the weather
might do again.
3. Name two parts of a car and the Earth resources in them.
7. The biggest soil problem in Australia is salinity.
4. What’s our second most important metal? What is the
rock from which it is extracted?
5. Using cement, we copy one of the ways that nature makes
a sedimentary rock. We call it____?
6. Ancient air bubbles in ice and some fossils can give clues
to what?
7. The biggest soil problem in Australia is____?
8. True
9. Earthquakes and volcanoes
10. Mainly, it is the dimension of time. Usually we do not
see the Earth changing all that much in our lifetimes. But
geology reveals great changes, introducing what happens
over enormous spans of time into our consciousness. It could
also be the dimension of what is under the ground which
most of us rarely consider.
8. T or F: Oil can be formed on land and also under the sea.
9