Artesian wells form when water flows through a permeable rock from a higher area to the area of the well. Artesian wells produce water flow without any additional pumping because of the water pressure in the rock, so they require a layer of impermeable rock beneath the permeable rock to block the flow downward. Thus, when a well is dug into the permeable rock, the water flows out under pressure.
The permeable rock that carries water for an artesian well is most commonly sandstone. Water soaks into the ground some distance above the well and permeates the rock. When it is trapped by impermeable rock, such as shale or clay, the weight of the water creates pressure. In natural settings, this can emerge from the surface near the bottom of the permeable layer as an artesian spring, but humans can create a flow deliberately by digging a well.
Artesian wells and springs are important sources of water in some environments, particularly arid plains near mountains. These sources of water have long been used by humans, but modern use has greatly depleted many of them. The modern demand for water, particularly for agriculture, can far outstrip the replenishment of artesian well sources.Learn More
A beach is any type of landform that lies along the shoreline of a body of water. The shoreline of a beach is formed naturally by the geographical end of the body of water, but the sand on the beach is formed over many years.Full Answer >
Most caves form in karst, which is a type of landscape composed of dolomite, gypsum and limestone rocks that gradually dissolves in the presence of slightly acidic water, according to National Geographic. Some caves are found in cliffs at the edge of a coastline. Others form in areas where the outer surface of a lava tube cools and hardens, and the molten rock’s inner content drains away.Full Answer >
A geyser is essentially an underground hot spring that, owing to pressure exerted against its constricted plumbing toward the surface of the ground, issues a stream of steam and boiling water from time to time. The term "geyser" is derived from the Icelandic word "geysir," which means to rush forth. A geyser stops erupting once its reservoir is empty, or the water below the surface cools.Full Answer >
Nearly 3.8 billion years ago, temperatures on Earth cooled below 100 degrees Celsius for the first time, allowing water, which existed on the planet in gaseous form, to condense into rain and collect on the planet's surface, according to the American Museum of Natural History. This water collected in low-lying areas, eventually becoming a primitive ocean.Full Answer >