Rock Falls in Yosemite National Park

What has been the main thing changing the shape of Yosemite Valley since the glaciers melted?

• Volcanic activity

• River erosion

• Rockfall

• Wind erosion

What can cause rocks to suddenly fall off a cliff or mountain?

• Heavy rainfall

• Snowstorms

• It seemed like nothing happened to make it start.

• All of the above

What happens to large rock pieces during a rockfall event?

• They slowly slide down the cliff face.

• They break into smaller pieces and free-fall.

• They remain intact and roll down.

• They are absorbed by the cliff.

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What was the main effect of the August 2009 rockfall on the talus slope?

• It created new water features.

• It caused the growth of new vegetation.

• It wiped out all the trees on the slope.

• It formed new rock formations.

How can one distinguish an old rockfall boulder from a fresh one?

• Old boulders are covered in lichen and moss.

• Old boulders are typically smaller in size.

• Fresh boulders have a darker color.

• Fresh boulders are always found near water sources.