Carl Blankenship, age 9, for his question:

What makes a geyser?

This summer, many of us visited Yellowstone National Park and saw the geysers spit up their frothy plumes of steam. These geysers have been spouting forth for hundreds of years, summer and winter. Each one of them is a sort of steam kettle buried in the ground. The hollow inside of the kettle is formed by a small cave, crack or crevice down in the earths crust. This is the hollow kettle which heats up the water.

The water is ground water which trickles and seeps to fill up the hollow kettle. The heat to boil the water comes from ancient lava which was buried before it had a chance to cool. The rocks around the underground kettle are hot enough to boil the water and turn it to steam. When this happens the kettle boils over and the steam is forced up in a. plume. This empties the kettle and more ground water seeps in to be boiled.