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
 

 

Early land plants
 

 

Largest mass extinction
 

 

Dinosaur extinction
 

 

Early hominid “Lucy”
 

 

 

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
 

 

First appeared:

Brachiopods
 

 

Height of diversity:

Eurypterids
 

 

Went extinct:

Ammonites
 

 

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
 

 

              Proterozoic
 

 

              Archean
 

 

             Pre-archean

Eras
Cenozoic
 

 

              Mesozoic
 

 

              Paleozoic
 

 

 

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): ___________________________