Time and Change

Chapter 4

Section 1 Earth’s History

• Objectives:– Describe the origin and early history of the

earth– Describe the processes of change on the

earth’s surface– Infer how different sedimentary rock forms– Communicate in a diagram how processes of

surface change are related

Skills Warm-up

• Time To Change– Look around the classroom and outside the

classroom.– Make a list of 10 objects or conditions that

don’t seem to change day to day.– How could they change and how long would it

take?

Earth’s History• How will you change over

the next few years? Ten years?

• How will your family and community change in the next few years?

• How will the earth change in the next few years?

Earth’s History• Compared to changes in the

______ _______, changes in the earth are ________ and _____________

• We usually think of the earth and its features as ___________ and ___________

• But they are not…….

Earth’s History

• Things that change – ___________– ___________– ___________– ___________

• They only change much more slowly, over enormous periods of time!!

Age of the Earth• Earth is

_________________• If you compare the age of

the earth to a 24 hour day, how old would you be?

• You would not be hours, minutes or even seconds old!

• Even at 100 years old, your life would only be ________ __ ___ ____________

Earth’s history is very long!You have to think about it in geologic time

Origin of the Earth

• 1. ~5 byo – cloud of _______ ________ _________.• 2. The matter was drawn to center by _______. The

center increased in _________, and grew __________________

• 3. _______ ________– light and heat was released. The sun was born.

• 4.Leftover matter began to clump and each clump became a _________.

Earth’s Early History• First billion years, the hot

surface ________ __________________

• Volcanoes ________ and gasses formed an ____________

• ________ __________, turned to liquid, and fell to earth as rain

• Eventually an ________ covered earth’s surface

Earth’s Early History• 3.8 million years ago, the

first small ___________ formed from _________ ___________– The first _______

_______came into being in the ________

– Some of these beings were able to produce _________ as a part of what process????

Earth’s Early History

• 2 million years ago the earth looked like it does today – It had __________ and

__________ and ________

– The atmosphere contained ________ and the sun’s energy created ________ ________

– But no ______ __________

Surface Changes

• Earth is still continuing to _________

• These changes are _______ and they follow _________ __________

• What are they??

______________ - when rock is broken down into smaller

particles• __________ _________

occurs through direct contact with atmospheric conditions, such as _____, ________, _______ and __________.

• _________ _________-involves the direct effect of atmospheric or biologically produced ___________

___________ – when small particles are carried away

• ______, ______ , _____, flowing ______, and ______ can all erode rock particles

• ___________ – the particles that are carried away

• Weathering/Erosion are _______ processes that cause ________ changes

• “______________” processes• __________ can disappear

and __________ can form

Surface Changes• ________ – the buildup

of eroded sediment– Occurs because of

_________• Where are particles

deposited?– Bottoms of _______

and _________, and ______ ________

• “___________” process• Occurs _______, all the

time

Sedimentary Rock• __________ from years of

weathering, erosion and deposition builds up, forming ___________ _________

• ______ layers form on top of ______ layers

• __________ of overlying sediment __________ lower layers

• __________ cement sediment together

• Sediments become ___________ _______

• Lowest layers are the ______

Uplift

• What would happen if weathering, erosion, deposition, and the formation of sedimentary rock were the only processes shaping earth??

Uplift

• Process by which parts of earth’s crust are ________ above others, forming _________/________

• There are always new, elevated __________ to be ______ ________

Skills Warm-up

• On Ice– When sheets of ice expand and advance from

the poles, much of earth’s water is frozen in ice.

– What do you think might happen to ocean levels?

– How might this effect shoreline erosion?

Changes in Life• _____________ are an

important part of earth’s history

• Living things __________ and ________ along with the earth

• _________ – inherited traits of a species change and new species _________

• Organisms that lived in the past left __________ of their _____________

• What are they called???

Changes in Life• _________– ______ or

______ of an organism that lived in the past.

• Organism was ________ in _________, became part of a ________ over time.– A fossil is therefore as old as the

rock of which it is a part.

• What have scientists learned from fossils?

• Living things _______ _________ over time (evolution)

• Many organisms are now ________

Fossils• Found in the _________• Preserved ancient ________ of _________• _________ fossils looked like organisms that

were alive – others did ______• The fossil record shows animals that were

preserved by being buried in the _______, _____ ______ or ______ _______

• Sedimentary rock-layers of sediment cover up the animals and _________ the remains

FOSSIL RECORD-INFORMATION OF PAST FORMS OF LIFE

• Tells of major changes in the ________ ________ of earth

• _____ __________ in Arizona – Coastline changes

• ______ __________ in N. America – Warmer climate

• What does a ____________ study?

FORMATION OF FOSSILShttp://www.pbs.org/wgbh/evolution/library/04/3/l_043_01.html

• Most are found in sedimentary rock –sediment forms when sand and silt from water settle to the bottom of a body of water

• Animals and plants that die in the water are compressed into rock by pressure from the water

FORMATION OF FOSSILS

• Bones and teeth may be preserved on land by shifting sand, mud, or volcanic ash.

• Footprints or soft tissue can be preserved if they fill with dust or ash. They are then covered by other materials and harden.

FORMATION OF FOSSILS• Petrification can occur when remains are

covered with water

• Dissolved minerals from the water replace the decaying tissues and harden

James Hutton• Scottish scientist – 1700’s• He observed that __________ were ____

_____than anyone had thought• He saw that earth’s ________ had changed

_________ over a long period of time• _______________________________ – the laws

of nature do not change over time• So, the _______ _________ that shaped the

earth in the past are still at work today• Gave birth to the modern science of

___________ and changed the human ________ __ ________

Changes in Climate

• Throughout earth’s history, the _________ ________ due to ____________ causes

• Sometimes the planet was ______ ___ ______

• Other times it was _____ and _____

• During cold times, the polar ice caps __________ ___ ______

• Huge sheets of ice spread from the poles to the ___________ _____________

Are Humans Changing the Climate?

• _______ _________– cities cause changes in temperature

• City temperatures are slightly _________ than surrounding areas

Are Humans Changing the Climate?

• Cutting down large areas of forest in ________ ________ changes ________ __________

• Deforested areas hold less ____________ – more rainwater drains to _________

• Less water ____________ into clouds – leads to _____ ____________

Are Humans Changing the Climate?

• Global changes – ________ ________

• Burning of _________ _________for energy increases the amount of _______ in the atmosphere

• Causes small __________ in the average __________ of the earth

Section 2Geologic Time Scale

• Objectives:– Explain how scientists determine the relative age

of sedimentary rocks– List the order of events that may result in an

unconformity being formed– Describe the major divisions of the geologic time

scale– Infer the relationship between the layering of

sedimentary rock and the geologic time scale

Skills Warm-up

• The Time of Your Life– Make a timeline showing the major events of

your life (so far).– Divide the timeline into stages based on these

events.– How many stages did you make? How did you

decide what was a separate stage?

Time Record

• How have scientists learned enough about the earth’s history to divide it into stages?

• How do they find out about events that took place millions or billions of years ago?

Time Record in the Rocks

• The rocks of the earth’s _________ hold all the __________.

• Scientists just had to learn how to “read” the ________ ___ _______ preserved in the rocks.

Rock Layering

• _______ _______ ________ provide evidence of past events– Ex) volcanic ash

layer– Ex) Layer with

marine fossils

Rock layers are stacked according to ______________ rocks are under _________ rocks.Therefore, drilling through the layers is like going _______ __ _____(as long as layers weren’t turned upside down by ___________).

RELATIVE AGE

To determine the ______ of a layer of sedimentary rock, or a fossil in such a layer, compare its ________ to other rock layers _________ it

You’d say, “This layer is younger than this layer” or “This layer is older than this layer”

This doesn’t give you an actual age in years, but an age “__________” to the other layers

RELATIVE AGE• Relative positioning –

________ _____ _________• For example :

– Layer of sedimentary rock formed from volcanic ash, beneath a layer of sedimentary rock deposited in a shallow sea.

– What can you infer from this evidence?

• The sea formed ________ the volcano erupted.

Relative Dating

• _________ _________ means identifying which rock units formed first, second, third, and so on

• It tells us the _________ in which events occurred, ______ how long ago they occurred.

Nicolaus Steno 1636-1686

• Danish __________• Credited with

describing a set of geologic observations that are the basis of ________ _________

Skills Warm-up

• Something Old …….– Think of something living or non-living that is

over 100 years old.– What evidence do you have that the object is

old?– How does it differ from a similar object that is

much newer?

Key Principles of Relative Dating1. ____ ______________ – states that in an __________

sequence of sedimentary rocks, each bed is ________ than the one above it and ____________ than the one below it.

2. ________________________________ – layers of sediment are generally deposited in a horizontal position.

3. _____________________________ – states that a _______ or ________ intrusion is __________ than the rock layers affected.

Unconformity• _________ in layering of rock• Layers that were _______ are covered

by horizontal layers.• Line between them – _____________ – Represents a break in ________

Absolute Age

• Determining the _________ ______of rocks, in _________• Obtained through _____________ __________

Radiometric Dating

• Radiometric dating is a technique used to date materials

• It compares the amount of a naturally occurring ______________ and its _____ _________, in samples

• The method uses known decay rates – ________ _________

Absolute Age

• It is the ______ source of information about the ______ of rocks and other geological features, including the age of the ________ itself

• Radiometric dating methods are used to establish the ________ _______ _________

Geologic Time Scale

• The geologic time scale is used by scientists to map the _______ and __________ between events that have occurred during the _______ of the Earth.

• It __________ estimates of the age of geological formations as provided by:• ___________________________________• direct evidence of _________ ___ _______in the rock

record as assembled by ____________

GEOLOGICAL TIME SCALE

Review Questions

• 1. How are sediments that become rock layers deposited?

• 2. How do layers become tilted?• 3. If folded rock layers erode, what happens to the

unexposed portion?• 4. If new sediments are deposited over the eroded

layers, what do earth scientists know?• 5. What is the difference between the relative age

and absolute age of rock layers?

Divisions of Geologic Time

• Scientists have divided geologic time into _______ large units called _______

• Era– _________ _________of geologic time– Each of the four eras cover a ___________

_________in Earth’s history

Precambrian Era• _______ and ___________ era in Earth’s history.• Includes all events from ________ ____________(6 billion

years ago) to a time about _______ million years ago• Ended when ______ and ____________ life forms appeared

– _________________

Paleozoic Era

• The _____ _________ ________following the end of the Precambrian Era

• _______ and ___________ began to live on land• Ended when many organisms became extinct

Mesozoic Era 245 – 66 MYA• The time of ____________• Most of the Earth had a _______,

________ climate.• Ended when the dinosaurs and

many other organisms ______ _______

• Extinctions might have occurred from an ____________

• Mass extinctions

Cenozoic Era• Our _______________ era

(66 MYA until now)• Climate has become much

________ ____ ________• Several _____ _______have

come and gone• Humans have been around

for a _______ part of this era

Periods and Epochs

• __________ units of time• Periods are smaller divisions

of eras, and epochs are smaller divisions of periods.– Era period epoch

• Why are these divisions more useful than stating a particular era?

• Ability to be ______ __________when dating something.

Telling Time - The Earth is the “ultimate clock”

• How do we define a Day? • The amount of time it

takes the Earth to ___________________

• How do we define a Year?

• The amount of time it takes the Earth to __________________

Telling Time - The Earth is the “ultimate clock”

• The earth’s ____________ define how people ___________ and __________ time.

• How would your life be different if the earth took ½ as long to complete one journey around the sun?

• What about your life would change if one rotation of earth around its axis took twice as long?

• The earth’s ______ ___ _____________doesn’t change, so are lives stay the same.