Review for Historical Geology Common Assessment
Essential Question: How does Uniformitarianism help explain Earth's features?
Vocabulary:

Uniformitarianism

Catastrophe

Neo-Catastrophe
Concepts: Match the Geologic event to the theory on Earth’s formation:
______________ Yellowstone, Volcanic eruption
A. Uniformity
______________ Formation of the grand canyon, 2 floods
B. Catastrophe
& weathering and erosion
______________ Sandstone forming
C. Neo-Catastrophe
Essential Questions: What is the difference between Relative age dating and Absolute age dating?
Explain whether each age description is relative or absolute. Give a reason for you answer

Middletown, PA became a town before Hummelstown, PA

Lower Dauphin High School was built in 1960.

Mrs. Fischl was born after Mrs. Cassel.

First Dinosaurs became extinct and then mammals evolved

The Earth formed 4.6 billion years ago.
Essential Question: What is relative dating, and how is it used to order past events?
1. Vocabulary

Law of Superposition

Principle of Cross Cutting

Principle of Original Horizontality

Principle of inclusions

Unconformity

Fault

Igneous

Sedimentary

Metamorphic
2.
Concept: Use the diagram below to answer the following questions. Layers 1, 4, 5, and 6 are
sedimentary rock; layers 2 and 3 are igneous intrusions; A is an unconformity; finally, B is a
fault.

Which sedimentary rock layer is older, 1 or 6? Explain your answer and name the scientific law that
you applied to reach your conclusion.

List layers 2, 4 and 5 in order from oldest to youngest.

How do layers B (Fault) and 2 (Igneous Intrusion) compare in age?

What is the boundary “A” called?

Layer 2 is an igneous intrusion. How could a geologist use layer 2 to infer the age of layer 6.

List the layers from oldest to youngest; include A & B with layers 1-6.
What does the fossil record show about how life has changed over time?
Vocabulary:

Fossil

Fossil Succession

Index Fossil

Correlation

Trace Fossil

Petrified Remains

Cast

Mold

Amber
Concepts:
1.
What are fossils?
2. What conditions are necessary to insure fossilization?
3. What is the principle of fossil succession?
4. Describe how a clam might become a fossil.
5. The remains of a large animal are found in a cave along with a large pile of fossilized dung (poop).
How can you incorporate this dung into your studies of this unknown animal?
6. How are the laws of superposition and the principle of fossil succession related?
Essential Question: What is absolute time and how is measured?
3.
Use the diagram and explain how Carbon 14 forms and is cycled.
Use the diagram12.25, what is the the maximum and minimum ages of the sedimentary rock layers.
Layer A: Max ____________ Min__________mya
Layer B: Max ____________ Min__________mya
Layer C: Max ____________ Min__________mya
Layer D: Max ____________ Min__________mya
Layer E: Max ____________ Min__________mya
Diagram 12.25 shows layers of sedimentary rock (labeled A, B, C, D& E) as well as some igneous
rocks. The igneous rocks include a lava flow which is cut by one of three dikes (igneous intrusions)
and a batholith (another igneous intrusion). The absolute ages of these igneous rocks were
determined through radiometric dating and give on the diagram. Check to see if the bottom layer
was age dated properly.
The bottom layer was found to have 1/32 parent isotope and 31/32 daughter isotope.

How many half-lives have past?

What is the age of the sample if the half-life is
4.6 million years?

If 5 grams of parent isotope was found, how
much original parent isotope was there?

Is the diagram correct? Is the bottom layer 23 million years old?
The cross section shown in figure 12.26 is from 5 different localities. Each one shows igneous
rocks and layers of fossil bearing sedimentary rocks. The absolute age of the igneous rocks (found
by radiometric dating) is also shown. Determine the absolute age range of each fossil at each site,
and record the ages on the table.
Fossil
Clam
Period
Tertiary
Gastropod
Triassic
Oyster
Cretaceous
Ammonite
Jurassic
Scallop
Mississippian
Snail
Silurian
Leaf
Recent
Absolute Age
4.
Describe how fossils can be used to find the relative
age of a rock?
5.
Describe how fossils can be used to find the
absolute age of a rock?
Figure 12.26 - cross section from 5 different localities
Essential Question: How do scientists organize the major events of Earth’s past?
Vocabulary:

Geologic Time Scale

Eon

Era

Period

Epoch

Evolution

Stromatolites

Extinction
Concepts:
1. How old is Earth?
2. What is the largest expansion of geologic time, covering about 88% of Earth’s history?
3. What is extinction and what caused most extinction?
4. Where do scientists believe life original formed?
5. When did Pangaea break up?
6. When did the dinosaurs exist on Earth?