Chapter 6 Study Guide
Cut out the following pieces of information and tape or glue them to index/flash cards. Make
sure that the numbers match up on each side. Use these flash cards to study 
Front side
Back side
1) Uniformitarianism:
1) A principle that states that
geologic processes that occurred
in the past can be explained by
current geologic processes.
2) Does uniformitarianism happen
suddenly or gradually?
2) Gradually
3) What is paleontology and what
do paleontologists study?
3) The study of past life and the
history of plants and animals
4) Geologic column:
4) An arrangement of rock layers in
which the oldest rocks are at the
bottom and the youngest rocks are
at the top.
5) Unconformity:
5) A break in the geologic record
created when rock layers are
eroded or when sediment is not
deposited for a long period of
time.
6) What is the most common type
of unconformity?
6) A disconformity
7) Amber & amber fossil:
7) Hardened tree sap - a organism
trapped and preserved in tree sap.
8) Trace fossil:
8) A fossilized mark that is formed
in soft sediment by the movement
of an animal.
9) What are some examples of
trace fossils?
9) Footprints, animal burrows, and
coprolite (animal poop )
10)
Paleozoic era:
10)
This era ended with the
largest mass extinction in Earth’s
history.
11)Which era are we in now and
when did it begin?
11)Cenozoic era, which bean about 65
million years ago.
12)
12)
The largest division of
geologic time
Eon:
13)
How many years of the
history of Earth do geologists
study?
13)
14)
14)
A principle that states that
younger rocks lie above older
rocks if the layers have not been
disturbed  “younger over older”
Superposition:
4.6 billion years
15)
How do geologists use the
geologic time scale?
15)
To divide Earth’s history into
manageable parts.
16)
Where are most fossils
preserved?
16)
17)
17)
Any method of determining
whether an event or object is
older or younger than other events
or objects.
Relative dating:
In sedimentary rock.
18)
What do scientists study to
learn about Earth’s history?
18)
Rocks and fossils
19)
Mesozoic era:
19)
Age of reptiles
20)
Modern geology:
20)
A science that combines
uniformitarianism and
catastrophism.
21)
What is catastrophism and
what is an example of a
catastrophe?
21)
The idea that geologic
change happens suddenly – an
asteroid hitting earth.
22)
Extinction:
22)
23)
Fossil:
23)
Preserved remains or other
evidence of an organism.
24)
What is a fault?
24)
A break in the Earth’s crust
25)
What does the rock and
fossil record represent?
25)
Geologic time
26)
26)
A fossil that is found in the
rock layers of only one geologic
age and that is used to establish
the age of the rock layers.
GEOLOGISTS USE TO DATE
ROCK LAYERS
Index fossil:
Death of a species
27)
Why is the fossil record
incomplete?
27)
Most organisms never
became fossils.
28)
Which part of an animal is
more commonly preserved?
28)
The shell or the bones
29)
Disconformity:
29)
A missing layer of rock
30)
Intrusion:
30)
Molten rock that has
squeezed into existing rock and
hardened
31)
Tilting:
31)
Rock layers slanted by
Earth’s internal forces.
Answer the following questions using complete sentences? Please use part of the question in
the answer and do not use pronouns unless you have already explained what “it”, “they”, “them”,
etc. is/are. These answers should sound like you are writing a textbook, not to your friends or
family :) Use your textbook index to find the page numbers that the following information can
be found on. You will be required to choose some of these to write as your essay answers.
32)
What is catastrophism? Catastrophism is the idea that geological change
occurred suddenly as a result of infrequent, disastrous events.
33)
Describe uniformitarianism. Uniformitarianism is the principle that the Earth is
shaped by gradual changes that are still occurring today.
34)
What is extinction? Extinction is the death of every member of a species.
35)
How do geologists us index fossils to date rock layers? Scientists found that
some types of fossi8ls are found in the rock layers of only one geologic age. Using
this information they can date the rock lyres where these fossils are found.
36)
Describe the geologic column and how it is assembled. The geologic column is an
ideal rock-layer sequence that contains all the known fossils and rock formations on
Earth arranged from oldest to youngest. Geologists create this record by
merging/combining all research from around the world.
37)
Explain what an unconformity is. Give an example. Unconformities are gaps in an
area’s geologic column. Examples include disconformities, nonconformities, and
angular unconformities.
38)
What present-day evidence suggests that the extinction of dinosaurs was the
result of a catastrophic event? What present-day evidence that suggests that the
extinction of dinosaurs was the result of a catastrophic event are huge craters that
have been found where asteroids and comets are thought to have struck the Earth.
39)
How is it that a crosscutting feature is always younger than the rock layers it cuts
across? The crosscutting feature is always younger because the rock layers had to
exist before anything could cut across them.
40)
Modern-day geologists realize that both uniformitarianism and catastrophism
account for all the geologic changes in the Earth’s history. Why do you think this is so?
While many geologic processes happen slowly, some occur suddenly. For example,
mountains take millions of years to be created, but an asteroid strike may have
caused the extinction of the dinosaurs.