Grades K–2 · Earth & Space
How can warm water come out of the ground?
Water coming out of the ground can be warm even on a cool day. It may have begun as rain that slipped into cracks and traveled down into the rock. Deep below the surface, the rock is often warmer than the ground under our feet.
As water passes the warm rock, energy moves into the water. The water warms. Warm water can rise through cooler water, and the push of other underground water can also help send it along a connected crack. The cracks provide a route back upward; the water does not travel through solid rock as if it were an open doorway.
The blue downward path becomes an orange upward path after passing the warm rock.
When that route reaches the surface, water flows out as a warm spring. Some springs receive heat from rock near volcanoes. Others are far from volcanoes and bring back water warmed during a deep underground journey. A warm spring joins rainfall, hidden cracks and Earth's heat in one flowing path.
About this explanation
Starting knowledge: Follow familiar changes in water, sunlight and rocks using pictures.
Sources
- National Park Service — Hot Springs and Geothermal Features
- U.S. Geological Survey — How Ground Water Occurs
- U.S. Geological Survey — Geysers, Fumaroles, and Hot Springs