Here's why:
* Pressure: The groundwater is trapped underground, under significant pressure from the surrounding rock.
* Boiling Point: The heat from the igneous rock raises the temperature of the water. Since the pressure is higher underground, the boiling point of the water is also higher than it would be at the surface.
* Eruption: Eventually, the water reaches its boiling point, turns to steam, and expands rapidly. The pressure overcomes the resistance of the surrounding rock, causing the water and steam to erupt at the surface.
While geysers are the most dramatic outcome, other features can also form:
* Hot springs: If the pressure isn't high enough to cause an eruption, the heated water can flow to the surface as a hot spring.
* Fumaroles: If the water boils away completely, leaving only steam, a fumarole can form.
* Hydrothermal vents: In deep-sea environments, heated water can escape through cracks in the ocean floor, creating hydrothermal vents.
Let me know if you'd like to learn more about any of these features!
