Aquifer

An aquifer is an underground layer of water-bearing permeable rock, or permeable mixtures of unconsolidated materials (gravel, sand, silt, or clay) (see also groundwater). Some productive aquifers are in fractured rock (carbonate rock, basalt, or sandstone). The study of water flow in aquifers and the characterization of aquifers is hydrogeology.

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This diagram indicates typical flow directions in a cross-sectional view of a simple confined/unconfined aquifer system (two aquifers with one aquitard between them, surrounded by aquiclude) which is in contact with a stream (typical in humid regions). The water table and unsaturated zone are also illustrated.

Water: :This article focuses on water as it is experienced in everyday life. See water (molecule) for information on the chemical and physical properties of pure water (H2O, hydrogen oxide)....

Gravel: Gravel is rock that is of a certain size range. In geology, gravel is any loose rock that is at least two millimeters in its largest dimension (about 1/12 of an inch), and no more than 75 millimeters (about 3 inches). Sometimes gravel is restricted to rock in the 2-4 millimeter range, with pebble b...

Silt: Silt refers to soil or rock particles of a certain very small size range (see grain size). On the Wentworth scale, silt particles fall between 1⁄256 and 1⁄16 mm (3.9 to 62.5 μm), larger than clay but smaller than a sand. In actuality, silt is chemically distinct from clay, and their ...