Nova projects a photo of a tall rocky bluff on the plains. A metal pipe sticks out of the top.
"This is Scotts Bluff National Monument," Nova says. "That pipe tells a story."
Rocket leans closer. "It is sticking up into the air," he says. "Did someone put it there like that?"
Raven reads the sign in the photo. "What do you notice about the ground around it?" she asks.
"The ground went down," Rocket says slowly. "The bluff is shrinking."
Weathering is the breaking down of rock. Heating and cooling, frost or chemicals can cause it.
Erosion is the removal of sediment, such as sand, silt or gravel, by wind or water.
At Scotts Bluff, runoff from summer storms and melting snow erodes the land more than wind does.
In 1933, that pipe was level with the top of the bluff.
The bluff has eroded about 18 inches in 75 years. Now the pipe sticks out.
That is slow, but over thousands of years, slow changes shape whole landscapes.
| Statement | True or false? |
|---|---|
| Weathering breaks rock down. | ? |
| Erosion carries sediment away by wind or water. | ? |
| Erosion always happens fast enough to watch. | ? |
Weathering and erosion are two different steps.
Weathering breaks rock into smaller pieces.
Erosion carries those pieces away with wind or water.
You read a real landscape like a scientist. Tomorrow we will review all four systems.