Groundwater and Aquifers
Water levels in wells are constantly changing both in the short term and over the long term. Some wells even have a seasonal change. In the short term, water levels can be lowered just by pumping water out of the well for use.
A well is said to have gone dry when water levels drop below a pump intake. This does not mean that a dry well will never have water in it again, as the water level may come back through time as recharge increases.
A confined aquifer is an aquifer below the land surface that is saturated with water.
An aquifer is a geologic formation that can store and transmit water to wells, springs and some streams.
Artesian well water is water from a well that taps an aquifer that is 'confined'. This aquifer is water-bearing rock below ground that is surrounded by other rock or material that does not allow water to pass through.
Let's assume that you get your water from the local water department through pipes buried below the streets. In other words, you don't have your own well in your back yard. Chances are that you get your water through the magic of gravity or pumps.
Probably you've seen this when driving on a road that has been cut through a hill. You are really seeing an exposed portion of water-bearing subsoil and bedrock.
Devils Hole is a tectonic cave developed in the discharge zone of a regional aquifer in south-central Nevada. The walls of this predominantly subaqueous cavern are coated with dense vein calcite.
Refer to the Illustration. Heat and volcanic gases from slowly cooling magma rise and warm the dense salty water that occupies fractured rocks above the Yellowstone magma chamber.
"Consolidated sediments" is essentially solid rock made from materials that have been metamorphosed or cemented together. For example, limestone is made of oceanic deposits of billions of shells; likewise, sandstone is made of tiny grains of sand.