Use the diagrams and charts to answer the questions, lab name:GEOLOGIC TIME HOMEWORK
GEOLOGIC TIME HOMEWORK
Using the figure below answer the following questions: Image CC BY S.A.
Units B and D are Igneous. The large swirly unit on the bottom is Metamorphic. A and F
are faults. C and E are Sedimentary layers. The wavy horizontal line is an unconformity.
1) What type of unconformity is present in this sequence? Draw an arrow to it.
2) Explain the formation of this unconformity.
3) Is igneous dike D older or younger than the fault A. Give your geologic principle
for proof.
4) Is the Igneous batholith B older or younger than Fault A? Give your geologic
principle to support your answer.
5) Is Fault A older or younger than fault F? Explain.
6) If Igneous dike D is determined by radioactive decay method to be 1.2 million
years old, what age information can you say about layer C. Explain.
7) What age information can you attribute to layer E, knowing the age of Dike D.
8) If Igneous batholith B has 25% radioactive parent material left and 75% stable
daughter material, how many half-lives have passed?
9) If the half-life duration of the radioactive material in batholith B is 1.5 million
years, how old is batholith B.
10)
Now that you know the age of batholith B and Igneous Dike D, Give a
possible age range for the unconformity.
Using the radioactive decay curve below answer the following questions:
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If sample A has 75% Radioactive Parent isotopes and 25% Stable daughter product, how
many half-lives have passed?
If the half-life for Sample A is 200 million years how old is Sample A.
Explain why half-life decay cannot be used accurately after 6 half-lives.
On the geologic time scale what percentage of the Earth’s time is represented by the
Precambrian.
How many Mass extinctions are recorded in this time scale?
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