The USGS Water Science School
This picture is really just showing an open pipe stuck deep into the ground—a water well, in this case. What is unique about this well, in southern Georgia, USA, is that it taps an artesian aquifer, in which the water saturating the aquifer is under pressure from being confined between two fairly impermeable layers of rock (above and below). Just as with the air in a blown-up balloon rushing out when the opening is untied, when a well taps an artesian aquifer, the water is pushed up the well pipe. Now, depending on the internal pressure, the water may not reach the land surface, but, as this picture shows, if the pressure is high enough water can be pushed dozens of feet above the land surface ... no pump needed.
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