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Lesson 13 | How Did the Grand Canyon Form?

By William Pollard
Last updated about 4 years ago
16 Questions

How Did the Grand Canyon Form?


More than 6.25 million people visited in 2017 alone. However, only a fraction of the vistors actually travel into the canyon itself. Descend below the rim, and the sense of the canyons beauty only grows with every step. The canyon is essentially an inverted, 6,000-foot, 277-mile-long mountain range. As you hike through the various paths you are dwarfed by sheer stone walls stacked to the sky and vistas that multiply with every turn. How did the immense natural wonder, the Grand Canyon, form?

Objective: Work through a serious of steps to determine the processes that created the Grand Canyon.
Section A: From what type of rocks is the Grand Canyon Composed?

Part 1: Classification of Rocks Found in the Grand Canyon

In order to better understand what kind of weathering broke apart the rock from which the Grand Canyon was formed, it’s important to establish what we know about the kind of rocks the Grand Canyon is made from.

Look at the images of the Grand Canyon below. Do you see any clues about what classification of rock the Grand Canyon might be made of? Use what you know about characteristics of different rock classifications to make an evidence-based claim.


Is the Grand Canyon made of igneous rock, metamorphic rock, or sedimentary rock?

What evidence from the images above supports your claim?

Part 2: Properties of Rocks Found in the Grand Canyon
Now that you have determined the classification of rock that the Grand Canyon is made of, let’s take a closer look at the specific rock types found in the Grand Canyon and their properties.

Geologists have shared the map symbols that represent rock types commonly found in the Grand Canyon below.


Drag the words that belong with map key

  • Shale
  • Limestone
  • Mostly feldspar and quartz
  • calcite
  • clay
  • sand
  • Sandstone
  • Mostly feldspar and quartz

One of the most common rock types found in the Grand Canyon is Limestone, based on the compostion of this rock why is that important in terms of weathering? (hint ESRT 16)

Section B: What type of weathering contributed to the formation of the Grand Canyon?

Part 1: Grand Canyon Climate

Examine the graph below. During which month is there the biggest difference between the average low temperature and the average high temperature? How much is the difference?

  1. One of the coldest months in the Grand Canyon is January. Examine the graph of January temperatures in the Grand Canyon below.
Does the Grand Canyon ever experience temperature below and above freezing (32 degrees F) on the same day? Be sure to cite evidence from the graph.

Examine the graphs below. Does it rain or snow (precipitation) at the Grand Canyon? How does the precipitation in the Grand Canyon compare to the precipitation in New York City?

Part 2: Read the text, Weathering. As you read, connect what you learned about the Grand Canyon’s climate and how this might offer clues about the type of weathering that may have broken apart rock to form the Grand Canyon.

What ideas from the text you think connect to what you learned about the Grand Canyon’s climate? Be sure to explain why you think they connect.

Part 3: Now that you have read about the types of physical and chemical weathering, make an evidence-based claim below about at least one type of physical weathering and one type of chemical weathering you think could have broken apart rock to form the Grand Canyon. Your responses should be written in the C-E-R format (3-4 sentences).

Claim: Answer the question in a complete sentence.
Evidence: Consider rock and mineral composition and climate at the Grand Canyon.
Reasoning: How does the evidence connect to the description of the physical weathering you claimed?

Physical Weathering Claim


Chemical Weathering Claim


Part 4: What type of erosion contributed to the formation of the Grand Canyon?

Great job making claims about the types of weathering you think could have broken apart rock to form the Grand Canyon! Your next job is to investigate erosion and make a claim about which type of erosion carried rock particles away to form the Grand Canyon.

Part 1: Below you will find animations or videos of different types of erosion processes. For each one, note observations about how the erosion process happens and if you think it might have contributed to the Grand Canyon’s formation.


Before you get started, revisit your observation notes from above and watch this video. This will be helpful for making possible connections to the erosion types below.


Describe the process of glacier erosion and if you believe it could have contributed to the creation of the Grand Canyon.

Describe the process of high gradient (steep) river/stream erosion and if you believe it could have contributed to the creation of the Grand Canyon.

Describe the process of low gradient (not steep) river/stream erosion and if you belive it could have contributed to the creation of the Grand Canyon.

Describe the process of wind erosion and if you belive it could have contributed to the creation of the Grand Canyon.

Describe the process of gravity/mass movement erosion and if you belive it could have contributed to the creation of the Grand Canyon.

Part 2
Geologists believe that more than one type of erosion contributed to the formation of the Grand Canyon. Now that you have investigated different types of erosion, make an evidence-based claim below about one type of erosion you think could have carried rock particles away to form the Grand Canyon. Your responses should be written in the C-E-R format (3-4 sentences).

Claim: Answer the question in a complete sentence. "One type of erosion I think may have carried rock particles away to form the Grand Canyon..."

Evidence: Scientific data to support the claim. (Consider the depth and width of the Grand Canyon.)

Reasoning: How does the evidence connect to the type of erosion you claimed?


CER Rubric