What would you call a natural water source that flows from rocks without any external energy source?

A natural water source that flows from rocks without any external energy source is referred to as a flowing artesian well. This term specifically describes a well that taps into a confined aquifer where the water is under pressure. When the well is drilled, the pressure causes the water to flow up to the surface naturally, without the need for mechanical pumps or external energy.

The key characteristics of a flowing artesian well are that it accesses groundwater from an aquifer that is sandwiched between impermeable layers, allowing the water within the aquifer to rise due to the pressure difference created by the geological formations. This phenomenon reflects the natural movement of groundwater and is a critical concept in hydrogeology.

Other options, while they may seem relevant, do not accurately describe this specific type of water source. Ground springs typically refer to water emerging at the surface due to geological formations but do not imply the same pressure-driven flow as an artesian well. Static wells refer to sources where water level does not fluctuate with pressure, and capped artesians pertain to wells that are sealed, which would prevent the natural flow of water.