Updated: Oct 19
Teddy Roosevelt once proclaimed the Grand Canyon as a must-see wonder, and a century ago, in February 1919, Congress officially recognized this natural marvel by designating it a national park. Yet the Grand Canyon's narrative stretches back much further in time. It beckoned its first human observers some 12,000 years ago, as the earliest Americans traversed the continent. By the 16th century, a few intrepid Spanish explorers ventured through its awe-inspiring depths. It was in May 1869 that John Wesley Powell, a one-armed Civil War veteran and future head of the US Geological Survey, led an audacious river expedition down the Colorado River, leaving a legacy of reports that solidified the Grand Canyon's reputation as a national icon.
The Grand Canyon's epic saga commenced almost 2 billion years ago when two tectonic plates collided, causing volcanic islands to merge and their rocks to transform into the dark-hued "basement" rocks, including the 1.84-billion-year-old Elves Chasm gneiss—the canyon's oldest known rocks.
Subsequently, between 1.75 billion and 1.25 billion years ago, an enigmatic gap appears in the Grand Canyon's geological annals, where erosion erased rock layers like missing chapters in a history book. The narrative recommences from 1.25 billion to 730 million years ago, as new rock layers—the Grand Canyon Supergroup—intermittently formed. Sediments settled at the ocean's bottom, forging layers, including a 1.25-billion-year-old limestone adorned with ancient algal fossils—the earliest life records in the canyon.
Objective: By the end of this lesson, students will have a better understanding of the Grand Canyon's geological and human history, its significance, and the challenges it faces today.
Large world map
Printed images and diagrams of the Grand Canyon's geological layers and rock formations. Link to layers
Whiteboard or blackboard
Colored pencils, markers, or crayons
Duration: Two class periods (approximately 45 minutes each)
Day 1: Exploring the Geological History of the Grand Canyon
Begin by showing students the Grand Canyon's location on a world map. Explain that the Grand Canyon is not just a beautiful natural wonder but also a place with an incredible history.
1: Geological Layers of the Grand Canyon
2. Present printed images and diagrams of the Grand Canyon's geological layers and rock formations. Explain the significance of each layer and how they formed over millions of years. Use a projector if available to provide a visual aid. Layers Link
Divide the students into small groups and provide each group with a printed image of the Grand Canyon's geological layers.
Have each group identify and label the different rock layers. Encourage them to color the layers in different shades to represent the various rock types.
After completing their diagrams, each group presents their findings to the class, explaining the significance of the different layers and their estimated ages.
Day 2: Uncovering Human History and Future Challenges
Recap the previous lesson and remind students of the Grand Canyon's vast geological history. Emphasize that people have also played a significant role in this natural wonder's history.
Activity 2: Human History and Future Challenges 2. Show images of Native American tribes that have lived in or near the Grand Canyon. Explain how their way of life has changed over time.
Discuss the importance of the Grand Canyon becoming a national park and its significance in American history.
Introduce the challenges the Grand Canyon faces today, such as climate change and water supply issues.
Divide the class into pairs and provide each pair with a blank world map.
Have students mark the location of the Grand Canyon on their maps.
Ask each pair to research and write down one interesting fact about the Grand Canyon's human history and one challenge it faces today.
Have pairs share their findings with the class and encourage a discussion about the importance of preserving the Grand Canyon.
Conclusion: 9. Summarize the key points about the Grand Canyon's geological and human history.
Discuss the role of stewardship in protecting this natural wonder for future generations.
Students can be assessed through their group presentations, the accuracy of their geological layer diagrams, and their contributions during class discussions.
Students can write a short essay about why they think it is important to protect and preserve natural wonders like the Grand Canyon. They can also suggest ways to address the challenges it faces.
Extension Activity (Optional):
Watch a short documentary or video about the Grand Canyon's geology and history, followed by a class discussion.