The Gusher EarthCache

The word artesian comes from the French town and province of Artois (called Artesium during Roman times) near Calais, where the first European artesian well was drilled in A.D. 1126, by Carthusian monks, and is still flowing today. The term artesian can be applied to any system in which groundwater is confined and builds up high hydrostatic (fluid) pressure. Water in such a system is able to rise above the level of the aquifer if a well is drilled through the confining layer (aquiclude), thereby reducing the pressue and forcing the water upward. For an artesian system to develop, three geologic conditions must be present.

1.the aquifer must be confined above and below to prevent water from escaping.

2.the rock sequence is usually tilted and exposed at the surface, enabling the aquifer to be recharged.

3.there is sufficient precipitation in the recharge zone to keep the aquifer filled.

The elevation of the water table in the recharge area and the distance of the well head from the recharge area determine the height to which artesian water rises in a well. The surface defined by the water table in the recharge area, called the artesian-pressure surface, is indicated by the sloping dashed line in the figure. An artesian well will flow freely at the ground surface only if the wellhead is at an elevation below the artesian pressure surface. In this situation, the water flows out of the well because it rises toward the artesian-pressure surface, which is at a higher elevation than the wellhead.

In addition to artesian wells, many artesian springs also exist. Such springs can occur if a fault or fracture intersects the aquifer allowing water to rise above the aquifer. Because the geologic conditions necessary for artesian water can occur in a variety of ways, artesian systems are quite common in many areas of the world underlain by sedimentary rock.

To log this cache, you will need to bring along a timing device,a wide mouth container of known volume, a thermometer and a camera.Measure the rate of water flow from the well (gallons per minute).

Record the water temperature.

Post a photo of your GPS'r in front of the spring.
Email me your answers, when you log your find it.
**Any logs without the required info will be deleted.**