Introduction: One of the most difficult things for the human brain to comprehend is the depth of geologic time because it is challenging to visualize the magnitude of numbers like a million or billion. This lab explores concepts in relative dating, absolute age dating, and fossil succession to explore how geologists structure Earth’s vast history.
PART 1: Understanding Geologic Time:
Use the https://ucmp.berkeley.edu/education/explorations/tours/geotime/gtpage1.html webpage to answer the following questions:
- How many pages would be in the “A History of the Earth” book if each page represented 10,000 years of Earth history?
- For the events listed below, fill in how many years ago the event happened, and what page it would be on in the “A History of the Earth” book.
Event | Years ago | Page # in book |
Formation of the Earth and Moon | ||
Earliest life appears |
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Early land plants |
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Largest mass extinction |
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Dinosaur extinction |
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Early hominid “Lucy” |
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- What is the difference between relative date and absolute date? (Use the U.S. history timeline you create to help answer this question.)
- What is the Law of Superposition (what does it tell us)?
- Fill in the following information for the fossils shown in step 7 of the activity.
Fossil | Fact about the organism | Date the fossil: |
Trilobite |
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First appeared: |
Brachiopods |
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Height of diversity: |
Eurypterids |
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Went extinct: |
Ammonites |
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Went extinct: |
- Which of the fossils is the earliest (oldest)? ________________________________________
- What is radiometric dating, and what does it tell us?
- Based on the data from the radiometric dating of the volcanic ash layers, what is the age range for the layer of rock the ammonite fossils are found in? _____________________________________
- The geologic time scales starts with the formation of the Earth. When did the Earth form? __________________________________
- Fill in the following information for the eons and eras in the geologic time scale.
Time Period | Fact | Millions of years ago | ||
Eons | Phanerozoic |
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Proterozoic |
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Archean |
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Pre-archean | ||||
Eras | Cenozoic |
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Mesozoic |
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Paleozoic |
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- Use the information from the geologic timeline to identify what period each of the following events occurred in.
- Animals first appear in the fossil record: _____________________________________
- Evidence of life on land: ____________________________________
- First trees and forests appear: ________________________________
- Pangaea forms: _______________________________________
- Largest mass extinction occurs: _____________________________
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- Dinosaurs roam the earth:__________________________________
- Dinosaurs go extinct:_______________________________________
- Mammoths, saber-toothed cats, giant sloths, humans, and ice ages
(aka, when the movie “Ice Age” takes place): ___________________________
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