Lesson 3: Geologic History of Utah

Grade(s) - 6-8

Topic: Geologic History of Utah

---

Brief Lesson Description:

In this lesson, students will learn how can we use sedimentary rocks and stratigraphy to learn about Utah’s past. Using skills learned in previous lessons, students will study sedimentary rock sequences from national parks in the Colorado Plateau to tell the story of Utah from 500 million years ago to now. After discussing the importance of the Colorado Plateau, students will go on a virtual field trip with 4 stops at national parks. At each stop, the student will make observations about the identified rock formation(s), including grain size, fossils, and sedimentary features, then use those observations to interpret the depositional environment of each formation. The provided handout will guide these observations and interpretations. Once each stop has been visited, students will describe the geologic evolution of Utah from 500 million years ago to present. This lesson is the culmination of the module, and students should be able to draw on skills learned in the previous lessons to complete this activity.

Learning Outcomes:

1. Use their knowledge of sedimentary rocks to identify depositional settings
2. Use stratigraphic principles to make a time-ordered history
3. Interpret a geologic history of Utah based on the rock record

Background Information:

1. Students should understand that sedimentary rocks form in specific environments, and how to diagnose depositional environments

    

2. Students should understand stratigraphic principles based on the previous lesson

Science & Engineering Practices:

1. Analyzing and interpreting data

2. Making an argument from evidence

Disciplinary Core Ideas:

• ESS2: Earth’s Systems

Crosscutting concepts: 

• Stability and change
• Cause and Effect

Possible Preconceptions/Misconceptions:

• Students may not fully understand how environments can change through geologic time

   

• Students will likely be unfamiliar with stratigraphic columns

To start, ask students “Why do we care about the past?”  Give students a couple minutes to brainstorm (there’s space for them to write their thoughts on the handout), then ask them for some of their answers. This should lead to a discussion that establishes the basic concepts of the lesson: we care about the past for multiple reasons, including to prepare for the future, understand how the present came about, and how things change over time, and additionally that sedimentary rocks are the clues we can use to figure out what happened in the geologic past.

This should allow the teacher to lead into the lesson by talking about how sedimentary rocks are the record of environmental change in the past, and so looking at stacked sedimentary rocks can tell us about the past environments and their change over time.

---

Explore

1. Open with quick background on geologic time and the Colorado Plateau. Through the lesson, students will grasp exactly how long geologic time is, and how radically things can change in that time. The Colorado Plateau will be our case study because it’s stable compared to other parts of the world, has thick sedimentary sequences, and, best of all, is right in our backyard! It records 500 million years of time, from the Cambrian Tapeats Sandstone to the Paleocene-Eocene Claron Fm. Discuss why that is useful for talking about geologic history – that it’s more “complete” (records more time) than other areas.
2. If necessary, review some of the skills from previous lessons. Most important to know for this class is how to diagnose depositional environments (and, in this case, continental environments vs marine environments) and the Law of Superposition (that the rocks on the bottom are oldest, while rocks on top are younger). The environments included in the powerpoint are those that students should know to complete the activity.
3. Virtual fieldtrip! The conceit of this activity is that students are going on a fieldtrip from Grand Canyon National Park to Zion National Park, then to Bryce Canyon National Park and finally Arches National Park. At each stop, they are provided with some information, including pictures, a 3D model, and a stratigraphic column. The handout should guide students through observations and prompt them to make interpretations. Perhaps work through the first stop, Grand Canyon National Park, as a class. Allow them to work through at their own pace, checking in as needed.
   2. The most important thing to explain for this activity is the stratigraphic column. These diagrams show the order of different rock formations, like the cross-section from lesson 2. However, these diagrams also contain the names and ages of formations. For this exercise, the “age-range” of rocks will be the name of the time periods involved (for instance, the Grand Canyon would be “Pre-Cambrian to Triassic.”
   3. After visiting each stop, the handout prompts students to organize the information they learned in charts. These charts will help students answer the following question.
   4. The questions at the end of the handout serve two purposes. The first question asks students to summarize the information they have gathered and the interpretations they’ve made into a geologic history of the Colorado Plateau. The second and third question are open ended and should serve to prompt discussion about the implications of this lesson.
4. After everyone has “returned” from their fieldtrip, review the geologic histories students created and discuss their answers to the final questions.

---

Explain

Concepts:

The geologic history of Utah is impressive, and showcases the magnitude of environmental change over time right here in our backyard.

Vocabulary: 

• Stratigraphic column – a diagram used to depict the vertical location of rocks in a certain area

   

• Formation – a named unit of sedimentary rock that is thick and extensive enough to be recognized over large areas

---

Evaluate

Formative Assessment: 

During the activity, check in with students to make sure they understand, and if they have any questions.

Summative Assessment:

At the end of the activity, review their geologic histories as a class to check understanding.