What Makes Old Faithful Erupt?
A crowd waits on a boardwalk in Yellowstone National Park, watching a quiet opening in the ground. Suddenly, water splashes upward. Within moments, a tall column of hot water and steam rises into the Wyoming sky. Old Faithful, one of the world’s most famous geysers, is erupting.
A geyser is a hot spring that sometimes shoots water and steam into the air. Old Faithful’s eruptions usually last between one and five minutes. They occur often, but not on an exact schedule. Park scientists use the length of one eruption to help predict when the next one will happen. A longer eruption is generally followed by a longer wait.
Heat Beneath Yellowstone
Old Faithful needs three main ingredients: water, heat, and a system of underground spaces and narrow passages. Much of its water begins as rain or snow. After soaking into the ground, the water moves downward through cracks in the rock.
Deep beneath Yellowstone, hot rock and a large area containing partly melted rock provide heat. Water traveling underground is warmed by the surrounding rock. This underground heat is called geothermal energy. “Geo” refers to Earth, and “thermal” means heat.
- predict:
- To say what is likely to happen before it happens.
- gathers:
- Comes together in one place.
- superheated:
- Heated beyond the usual boiling temperature without fully turning to steam.
- expelled:
- Forced or pushed out.
- cycle:
- A series of events that repeats.
- clues:
- Signs or pieces of information that help explain something.
- designated:
- Chosen or marked for a particular purpose.
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Preview questions from this passageShowHide
- 1What three ingredients does Old Faithful need, and what role does each play?
- 2How does water reach Old Faithful’s underground system?
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About this explanatory article passage for Upper Elementary
“What Makes Old Faithful Erupt?” is a explanatory article reading passage about Geothermal Features, written for Upper Elementary. It takes about 3 minutes to read (524 words) and comes with an interactive quiz and a printable worksheet with comprehension questions and an answer key.