Book 20, Question 111
Why Do Big Granite Domes Peel Like Onions?
Big granite domes peel like onions because the rock swells and cracks into curved sheets. Scientists call this peeling exfoliation. It happens very slowly, over thousands of years.
More fun facts
- Some granite domes peel in curved layers, like onion skins.
- This is called exfoliation.
- Slabs break off along curved cracks parallel to the surface.
- The granite formed deep underground and rose as rock above wore away.
- In 2014, a granite dome in California cracked and peeled on a hot summer day.
Sources: National Park Service, U.S. Geological Survey, National Park Service
Questions kids ask
What is exfoliation?
It is when granite peels off in curved layers, like onion skins.