Deciphering Earth’s History
Virtual Investigation – 8
Answer the following questions as you move through the investigation.
The Law of Superposition states that an ____________________________ sedimentary rock
layer is __________________ than the layers above it, and __________________ than the
layers below it.
The Principle of Original Horizontality states that sedimentary rocks left undisturbed will
remain in ______________________________ layers.
True or False:
Horizontal rock layers may become tilted and deformed by movements of
Earth’s crust after they are deposited.
Prior Knowledge:
What is igneous rock?
The Law of Crosscutting Relationships states that an ________________________ intrusion or
_________________ is always ____________________ than the rock layers it cuts through.
Extend Your Thinking:
How might the igneous intrusion have formed?
Put the correct numbers in the circles.
Matching – Write the letter of the answer on the line:
A) Unconformity
B) Disconformity
C) Nonconformity
D) Angular Unconformity
_______ Missing times in the rock record due to no rocks forming, or removal of rocks from
erosion
_______ Sedimentary rocks sitting on top of igneous or metamorphic rocks
_______ Horizontal rock layers resting on top of rock layers that sit at an angle
_______ Sedimentary rock on top of other sedimentary rock with parts missing from the rock
record
Think about it:
Why might metamorphic or igneous rocks be responsible for removing part of the rock
record?
Matching – write the letter on the line:
A) Disconformity
B) Nonconformity
C) Angular Unconformity
Fossil Record:
During what period did layer A form (circle one)?
Cambrian
Silurian
Ordovician
Devonian
During what period did layer D form (circle one)?
Cambrian
Silurian
Ordovician
Devonian
How many millions of years passed between the formation of layer D and layer H?
202
244
444
488
Paleogenic Puzzles – write the number in the circles:
Fossil Chart:
Oldest possible age of the impact layer: ___________ million years old
Youngest possible age of the impact layer: __________ million years old
Is the layer Walter found possibly from the impact that wiped out the dinosaurs? ______
Could Bruce’s fossil have come from layer 7? _______
Which layer did it actually come from? _________