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Science Launch G4 / Week 11 / Monday
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Week 11 · Rock Layers and Weathering

Monday

Stripes in the canyon
// Reading Earth's story and watching it change
⏱ about 15 min

Monday: Stripes in the canyon

Rocket and Raven stand at the edge of the Grand Canyon. The walls drop away in stripes of red, tan and cream.

Far, far below, a thin green river winds through the bottom.

"It looks like a giant layer cake," Rocket says. "Which layer came first?"

Raven holds her notebook against the wind. "What do you notice about how the stripes are stacked?"

Nova zooms her camera eyes down the canyon wall. "Here is a clue," she says. "Think about how you stack books on a table."

Layers tell time

Many rocks form in layers, one on top of another.

In the Grand Canyon, the bottom layer formed first. Each layer above formed later. The youngest rocks are on top.

The oldest rocks in the Grand Canyon are about 1.8 billion years old.

The Colorado River at the bottom has been carving away rock for five to six million years.

The river in the bottom is evidence that, over time, moving water cut a canyon through the layers.

OLDEST LAYER TO YOUNGEST LAYER
  • ?The bottom layer
  • ?A middle layer
  • ?The top layer
WHY THIS EXERCISEIn layers that formed one on top of another, the bottom is oldest and the top is youngest.
CANYON CLUES
  • Read the question.
  • Tap your answer.
Where are the youngest rocks in the Grand Canyon?
What carved the Grand Canyon?
About how old are the oldest Grand Canyon rocks? Write the number of billions of years.
WHY THIS EXERCISERock layers can hold a story that is almost two billion years long.

Reading a rock stack

Geologists read rock layers from the bottom up, like turning pages in a book.

The bottom page was written first. Each page above was added later.

So the deeper you go in the canyon, the farther back in time you travel.

LAYER LOGIC
  • Read the question.
  • Tap your answer.
Where are the oldest rocks in the Grand Canyon?
For how long has the Colorado River been carving the canyon?
You hike down into the canyon. What happens to the age of the rocks?
StatementTrue or false?
Many rocks form in layers.?
The youngest Grand Canyon rocks are at the bottom.?
Moving water carved the Grand Canyon.?
Each new layer forms on top of older rock.?
WHY THIS EXERCISENew layers form on top, so the bottom is oldest.
A flat band of rock that formed on older rock is a rock ____.
The river at the bottom of the Grand Canyon is the ____ River.
Try it
Stack five books one at a time. Say a day of the week for each one.
Which book went down first? Where is it now?
Which book is the youngest in the stack?
Draw a canyon wall with four colored layers and a river at the bottom. Label the oldest and youngest layers.

You read your first rock layers! Tomorrow we look for fossils hiding in them.