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:

1. How many pages would be in the “A History of the Earth” book if each page represented 10,000 years of Earth history? __________________________________

 

2. 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
Early land plants
Largest mass extinction
Dinosaur extinction
Early hominid “Lucy”

 

3. What is the difference between relative date and absolute date? (Use the U.S. history timeline you create to help answer this question.)

 

 

4. What is the Law of Superposition (what does it tell us)?

 

 

5. Fill in the following information for the fossils shown in step 7 of the activity.

Fossil	Fact about the organism	Date the fossil:
Trilobite		First appeared:
Brachiopods		Height of diversity:
Eurypterids		Went extinct:
Ammonites		Went extinct:

 

6. Which of the fossils is the earliest (oldest)? ________________________________________

 

7. What is radiometric dating, and what does it tell us?

 

 

8. 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? _____________________________________

 

9. The geologic time scales starts with the formation of the Earth. When did the Earth form? __________________________________

 

10. Fill in the following information for the eons and eras in the geologic time scale.

 

Time Period			Fact	Millions of years ago
Eons	Phanerozoic
Proterozoic
Archean
Pre-archean
Eras		Cenozoic
Mesozoic
Paleozoic

 

11. 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: _____________________________

 

• 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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