Chapter 7: A Trip Through Geologic Time
Learning Target
Lesson 1
I can explain how
fossils form . . .
I can identify the
different kinds of
fossils . . .
Vocabulary Word
fossils
molds
Definition
Facts or Examples
______________remains
or _________ of living
things. Most fossils form
when living things die
and are buried
in__________.
A ___________ area in
sediment in the
__________of an
organism.
The sediment slowly hardens
into ______and preserves the
shapes of the organisms. Most
fossils form from animals that
lived in or near___________,
lakes or shallow ________.
cast
A solid ________ of the
shape of an organism
petrified fossils
A fossil in which
___________ replace all
of an organism or a
part.
carbon films
trace fossils
An extremely thin
___________of carbon
on rock that occurs
when sediment buries
& organism and some
________ escape.
A fossil that provides
____________ of the
___________of ancient
organisms
Often formed when water
deposits ___________ and
sediment into a __________.
Examples include dinosaur
bones and tree trunks. Water
evaporates.
This can preserve delicate
parts of ____________and
____________.
Ex. footprints, trails, burrows,
nests
Symbol/Picture
preserved
remains
I can describe what
fossils tell about
organisms and
environments of the
past . . .
paleontologists
extinct
relative age
absolute age
I can sequence rock
layers by using the
laws of superposition ,
cross cutting and
index fossils . . .
Scientists who study
_________________
evolution
Lesson 2
I can describe how
geologists determine
the relative age of
rocks…
An entire organism
can be preserved in
tar or ____________
(tree resin) or from
freezing.
Law of
superposition
La Brea tar pit in California
The fossil record provides
evidence about the
____________of life and past
environments on Earth. Shows
how organisms have
____________over time or
changes in climate
The change in living
things over time.
An organism that no
longer _________ and
will never again live on
Earth.
The age ___________ to
the ages of other
rocks.
The number of
_________ that have
passed since the rock
___________
In undisturbed
_______________
sedimentary rock
layers, the oldest layer
is at the ___________
Each higher layer is
____________ than the layers
below it.
extrusion
intrusion
fault
index fossils
I can explain how
unconformities and
folding can alter the
order or rock layer…
unconformity
Lava that hardens on
the _________ and
forms ___________
rock
When ________ pushes
into bodies of rock
__________the surface
and cools and
hardens into a mass of
igneous rock
A __________ in Earth's
crust
A fossil that is widely
____________ and
represents an
organism that existed
for a geologically
________ period of
time.
The surface where
new rock layers
________ a much older
rock surface beneath
them.
Extrusion is always _________
than the rocks below it.
Part of the law of cross cutting
(You can't cut a pb & jelly
sandwich until you make one)
An intrusion is always
_________________ than the
rock layers around and
beneath it.
Also the law of cross cutting!
A fault is always
__________than the rock it cuts
through. Geologists find the
_________ age of the youngest
layer cut by the fault.
They can be used to
__________ rock layers from
different ______________.
A ______in the ____________
record. Is shows where rock
layers have been _______ due
to ___________
folding
Sometimes, forces
inside Earth fold rock
layers so that the
_____________ rock
layer may be on
the_______________.
Lesson 3
I can explain what
happens during
radioactive decay …
radioactive
decay
Atoms of one
__________ break down
to form atoms of
another element
half-life
The time it takes for
Radioactive elements release
__________ and __________ in
the process of radioactive
decay
half of the ___________
atoms to ___________
I can describe what
can be learned from
radioactive dating…
Scientists determine
the amount of a
radioactive element in
a rock.
Potassium-argon
dating
Potassium -40 decays
to argon-40, half life is
_______ billion years
Then they compare that
amount with the amount of
the stable element into which
the radioactive element
decays.
Good for dating very old
_____________
They use this information
and the half life of the
element to calculate the
age of the rock.
Carbon-14
dating
Carbon 14 decays to
Nitrogen 14, half life is
_____________ years
Not good to date fossils older
than ___________ years or
_____________ because they
don’t contain much carbon
geologic time
scale
A record of the
geologic _________
and _____________ of
life forms as shown in
the __________ record.
Because the time span of
Earth’s past is so __________,
geologists use the geological
time scale to show
Earth’s____________.
Precambrian
Time
______ % of Earth’s
history, ended
________million years
ago
Lesson 4
I can explain how
and why the
geologic time scale
is used to show
Earth’s history…
eras
Long units of time
Very few fossils
1. ________________ (fish,
insects, land plants)
2. ________________ (reptiles,
dinosaurs, flowering plants)
3. _______________ (mammals,
grasses & humans)
See picture on next
page
periods
______ are divided into
smaller units of time
called periods.
Paleozoic has Cambrian,
Ordovician, Silurian,
Devonian, Carboniferous,
Permian
Mesozoic has Triassic, Jurassic,
Cretaceous
Cenozoic has Paleogene,
Neogene, Quarternary
Lesson 5
Scientists think that
Earth began as a ball
of_________ , rock and
____________ in space.
I can explain how
Earth developed
during the
Precambrian time . . .
comet
A ball of dust, gas, and
ice that orbits the
_____. Volcanic
eruptions &
__________with comets
add CO2, water
vapor, N2, and other
gases to our
atmosphere.
____________pulled this mass
together. The __________ from
these collisions raised the
____________________ so high
that the Earth __________.
____________ materials
sank toward the center
forming the __________
core. The Earth is _____
billion years old.
Less than _________ million
Scientists have found
years after the Earth formed,
_________ of single celled
the rock at the surface
organisms from _____
formed______________________.
billion years ago.
Lesson 6
I can describe the
major events of the
Paleozoic Era . . .
________________
– invertebrates
in ocean
____________– fish,
Silurian – plants and
insects, _____________ –
Age of Fishes,
amphibians
___________________– reptiles,
swamp plants turned into
__________ millions of years
later
__________– Pangea
formed, Mass extinction
_____ ocean species,
____ land species died
out.
invertebrates
Animals without
______________
vertebrates
Animals with a
___________
Ex. Jellyfish, _________,
sponges, Brachiopods and
___________ all lived in
Cambrian ocean.
__________ fish evolved in the
________________ time period
____________ period – plants
became abundant in ________
areas.
Devonion Period – plants in
__________ areas
first land plants
Ferns
early fish
Fish with _______, bony
skeletons, _________
and sharks
_____________ Period known as
the Age of Fishes
amphibian
An animal that lives
part of its life on
________ and part of its
life in the _________.
The first amphibians evolved
from the ______________.
reptiles
Animals that have
________skin, lay eggs
that have tough,
___________ shells
Small reptiles evolved during
the ___________________
period.
I can describe the
major events of the
Paleozoic Era . . .
I can describe the
major events of the
Cenozoic Era . . .
Mesozoic Era
known as Age of
____________
Cenozoic Era –
________________
evolved to live
in land, water,
air
___________– First
dinosaurs appeared,
some small mammals
____________ – land dinosaurs,
first birds
__________ & Neogene
– whales and dolphins,
first grasses, large
mammals and birds
__________________ – glaciers,
Ice Ages, Modern ___________
190,000 years ago.
________________ –
reptiles, birds, flowering
plants. ___ million years
ago – mass extinction.
Learning Targets Chapter 7
Lesson 1
I can explain how fossils form . . .
Most fossils form when ____________________ hardens into ___________, preserving the _________________ of organisms.
I can identify the different kinds of fossils . . .
Fossils include _____________, ________________, ________________ fossils, ____________ films, ______________ fossils, and
________________ remains.
Lesson 2 I can describe how geologists determine the relative age of rocks…
In ____________________ sedimentary rock layers, the _____________ layer is generally at the bottom. Each layer is
________________ than the layers below it.
I can explain how unconformities and folding can alter the order or rock layer…
____________in the geologic record and __________ can change the ____________in which rock layers appear.
Lesson 3 I can explain what happens during radioactive decay …
During radioactive _________, the atoms of one __________ break down to form atoms of another element.
I can describe what can be learned from radioactive dating…
In radioactive dating, scientists compare the amount of a _______________ element in a rock with the amount of the
________________ element into which the radioactive element _______________.
Lesson 4 I can explain how and why the geologic time scale is used to show Earth’s history . . .
Because the time _________ of Earth’s _________ is so great, geologists use the geologic time scale to show Earth’s history.
After Precambrian time, history is broken down into 3 __________________ and then many smaller ___________.
Lesson 5 I can explain how Earth developed during the Precambrian time . . .
Scientists think that Earth began as a ball of ______, rock, and ________ in space. ____________ pulled this mass together.
Lesson 6 I can describe the major events of the Paleozoic Era . . .
During the Paleozoic Era, a great number of different organisms _______________.
I can describe the major events of the Mesozoic Era . . .
_____________ spread widely during the Mesozoic Era.
I can describe the major events of the Cenozoic Era . . .
During the Cenozoic Era, ________________ evolved to live in many different ________________________.