1. Investigation 1 – Earth is Rock
Part 3: Correlating Grand Canyon Rocks

2. Focus Question
How are the rocks from the two Grand Canyon sites related to each other?
1. Focus question: How are the rocks from the two Grand Canyon sites related to each other?

3. Which rock is at river level at Mile 52?
Rock Column Model
Which rock is at river level at Mile 52?
Which rock is directly above Rock 4?
2. Explain the rock column model
Distribute notebook sheet 8, Grand Canyon Rocks – THEY WILL CUT THIS PAPER APART
Text books – Refer to photographs of Mile 20 and Mile 52 (pages ) and observations from Part 2
Answers: 1. Rock 4, a limestone. 2. Rock 5, another limestone
Have students check and confirm that the rock types they learned about in Part 2 (limestone, sandstone, and shale) match the rock types listed

4. Organize rock samples in columns
Place the rocks in the appropriate box on your group’s Grand Canyon Rocks sheets.
For example: Place rock 4 in the rectangle labeled “Rock 4—Limestone”
Do this for all rocks
3. Organize rock samples in columns
-Have out Mile 20 and Mile 52 rock boxes for groups

5. Compare the rock layers found at both sites
Compare the rocks
Compare the rock layers found at both sites
Look for similarities and differences between the rock layers at both sites
Explain your observations and conclusions
4. Compare the rocks
Have students discuss and share their Grand Canyon Rocks sheets
If struggling, ask,
“What do you notice about the rocks at both sites?”
“Are any of the rocks the same at both sites?”
“What do you notice about the order of the rocks?”

6. Each group will report their observations
Discuss observations
Each group will report their observations
5. Discuss observations
Answers could include:
Some of the rocks are the same at both sites
Rocks 4, 5, 10 don’t have an exact match
Where the rocks match, their sequence in the column is the same

7. Rock names 10 Kaibab Limestone 9 Toroweap Limestone
8 Coconino Sandstone
7 Hermit Shale
6 Supai Sandstone
5 Redwall Limestone
4 Muav Limestone
6. Introduce the rock names
Say, “Geologists who have studied these rocks in the Grand Canyon have given them official names to identify them. Many of the names are Native American in origin.”
10 (KYE-bab)
9 (TORE-o-weep)
8 (co-co-nee-no)
6 (soo-pye)
4 (moo-ov)

8. Which site is farther east?
Line up the rock layers
On our Grand Canyon Rocks sheets, we have Mile 20 and Mile 52 right next to one another. However, on the river, how far apart are the two sites?
Which site is farther east?
7. Line up the rock layers
Have students put the rocks back into plastic boxes at this time.
Answers to slides (1 – 32 miles or 51 km, 2 – Mile 20)
Say, “I’d like you to cut your two rock walls apart and move them apart to see if you can get even more information about how the rocks in the Grand Canyon are related to each other.”

9. Line up the rock layers cont.
Use the dashed lines as guides to cut the Grand Canyon Rocks sheet into two parts
Turn the white paper lengthwise, so that the long side is horizontal. Label the top of the page “Grand Canyon Rocks Lineup”
Place the two rock walls on the white paper. Leave as much space between the rock walls as you can Because Mile 20 is farther east, place that site to the right and Mile 52 to the left.
Work with others in your group to decide how best to position the rock walls on the lineup sheet
Students need scissors and a sheet of white paper for each student.

10. Discuss rock lineup
webContent/Contribution%20Folders/FOSS/multimedia/Earth_Histor y/grandcanyon_rock_correlation/index.html
8. Discuss rock lineup
Have groups share their ideas about position of the rock walls
Suggest they look at the Grand Canyon poster for ideas about placement
If students suggest positioning the rock walls so that rocks of the same kind are aligned horizontally ask “Explain your reasoning for doing this”
Suggest that everyone position the rock walls in this way
Demonstrate with link in slide
With the two rock columns spread apart, and Mile 20 to the right, match the rocks by shifting the columns up and down until identical rocks line up.
If using a photocopy to demonstrate, tape the two columns in place. Students will tape/glue the columns on their white paper labeled “Grand Canyon Rocks Lineup”
Draw horizontal lines between the two rock walls, connecting the tops and bottoms of the similar rocks. Draw diagonal lines to connect the two segments of the river.
Label a place on the river line that would be the 36 mile (51 km) mark (about halfway between the two rock walls)

11. Asses your progress Look at your sheet and double check accuracy
9. Asses progress: Scientific practices
What to look for:
Students create a model of the rock layers and correlate the two sties by aligning similar rocks in horizontal layers (rocks 6, 7, 8, and 9 should be aligned)
Students make inferences about how the rocks might be layered underground and indicate this by drawing horizontal lines between sites.
Students represent the dropping elevation of the river as it flows from east to west by drawing a slanted line

12. In what other context have you used the word layer?
Layers
In what other context have you used the word layer?
10. Introduce layer
Say, “Some rocks at Mile 20 and Mile 52 are the same. We can infer that they stretch between these sites. Geologists describe these flat expanses of rock as layers. Layers can be thick or thin, but they extend over a large area, in this case at least 32 miles (51 km) between sites. In some cases the rock layers have been exposed, and in others the layers stretch underground.
Example answers to slide: Cakes, paint, peanut butter, clothing, etc.
Say, “Think of the rocks in the Grand Canyon as layers in a cake. Just as you slice through a cake with a knife and expose the layers inside, the Colorado River cut through the rock layers in the Grand Canyon, exposing the edges of the rock layers.

13. Look at the Geologic Cross Section of the Grand Canyon poster
Cross-section poster
Look at the Geologic Cross Section of the Grand Canyon poster
Only in places where erosion has “sliced the cake” can we see the layers that exist beneath the surface
11. Refer to the cross-section poster
Show students the layers of rocks on the Geologic Cross Section of the Grand Canyon poster.
Point to location of the Grand Canyon
Point out that the layers of rocks visible on this diagram extend over 100 miles (160 km) underground
Only in places where erosion has “sliced the cake” can we see the layers that exist beneath the surface

14. Fill in the rock layers 12. Fill in the rock layers
Say, “Geologists use symbols to designate the different kinds of rock, particularly on maps and other kinds of geological illustrations.

15. - A finished lineup might look like the slide
Students keep this in their folders/journals
13. Extend the investigation with homework
Once students have copied the rock-layer key and started with a few layers in class, they can finish drawing and coloring the layers at home.
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