Chapter 21 the ground water system

Perched water table

A second water table resting on top of an impermeable layer above the general water table from an area

Natural bridge

A section of stone that arches over a narrow walled valley formed by erosion in karst topography. It is believed to be the remnant of a cave roof where the rest of the roof on both sides of the bridge has collapsed

Flowstone

A cave formation containing deposits left by a thin film of water flowing over the wall or floor of a cave rather that dripping form the ceiling

Shelf

A cave formation of flat deposits of calcite than precipitated on the surface of standing water.

Column

A cave formation that forms when a stalactite merges with a stalagmite

Sinkhole

A depression the ground that occurs when the roof of a solution cave collapses at a single point

Shield

A flat,rounded deposit of calcium carbonate attached to a cave ceiling,wall,or floor

Cone of depression

A inverted cone-shaped lowering of the water table cnetered on a well in an area where the rate of water removal exceeds the rate of water percolation

Streamless valley

A karst valley that contains an abandoned stream bed because the stream has been diverted underground.It can be a rivulet,brook, stream,creek, or river

Spring

A location,usually on a hillside, where the water table intersects the ground and water flows onto the ground surface more-or-less continuously

Stalagmite

A narrow,conical mineral formation growing upward from the floor of a cave,usually deposited by water dripping form a stalactite

Appearing stream

A stream that seems to flow directly out of a hillside.One of the characteristic features of kart topography

Disappearing stream

A stream that seems to vanish into a hole in the ground. It occurs when chemical erosion opens a hole through the ceiling of a cave that underlies the stream bed, allowing the water to flow into the cave rather than down the hill.One of the characteristics features of karst typography

Bacon

A stripped ribbon of flowstone in a cave that looks like strips of salted bacon

Solvent

A substance that breaks down other substances into their constituent molecules or ions and forms a uniform mixture. Water is often called the "universal solvent

Curtain

A thing sheet of dripstone that hangs form the ceiling of a cave

Artesian well

A well sunk into a rock formation where groundwater pressure is adequate to provide a constant flow of water without pumping

Stalactite

An icicle-shaped mineral formation hanging from the ceiling of a cave,deposited by dripping water.

Cave

An underground tunnel or chamber of natural origin that is accessible form the earths surface

Speleoothem

Any cave formation deposited by dripping or flowing water.

Dripstone

Cave deposits that are formed from the precipitation or minerals contained in groundwater that drips on the same spot repeatedly. Stalactites and stalagmites are examples of dripstones

Impermeable

Describes rock through which liquids and gases cannot penetrate because of the absence of connected pores, voids, or cracks of sufficient size

Permeable

Describes rock where the size and number of the interconnected pores is sufficient for liquids and gases to penetrate or pass through

Porous

Having many small open spaces

Spelunker

In the U.S. a person who explores and maps cave as a hobby. Also known as a caver

Water table

The level below which the ground is saturated with groundwater

Hydrologic cycle

The natural water cycle in which water evaporates into the atmosphere from oceans, lakes, and rivers, clouds develop from the vapor, and the water falls to the ground as precipitation and then returns to the rivers,lakes, or oceans

Zone of aeration

The zone within the ground above the water table in which the spaces between soil particles are filled with air.

Capillary fringe

The zone within the soil horizons immediately above the zone of saturation where water has worked its way upward a short distance from the water table by capillary action

Karst topography

Topography in soluble nonclastic sedimentary rocks such as limestone that is characterized by solution caves,natural bridges,streamless valleys, and sinkholes

Recharge zone

any area where rainwater or stream water seeps through to the water table to resupply groundwater in an aquifer

Groundwater

any water from natural sources found underground

Zone of saturation

ground below water table