Heavens & Earth Chapter 9

Abrasion

A process of mechanical or physical weathering where a rock or particle is ground against another rock or particle.

Alluvial fan

A flattened cone-shaped deposit at the base of a mountain. The sediments in the fan usually accumulate by stream, mud flow and debris flow processes.

Aquiclude

A rock layer that prevents the flow of groundwater or other fluid.

Aquifer

A rock that stores groundwater in its pore spaces.

Artesian well

A well where the water comes out of the ground under pressure. No pumping is needed.

Base level

A topographic level where water can flow no further. Sea level is the ultimate base level. Lakes can be local base levels.

Bed load

Coarse material that is carried along the bottom of a stream bed.

Braided stream

A set of intertwining stream channels.

Capillary fringe

A zone just above the water table where water is drawn upwards by capillary action.

Cavitation

A very powerful mechanical weathering process that happens when vacuum bubbles implode, causing a "sledgehammer-like" effect on a solid material.

Channel deposits

Sand, gravel, boulders, and other rocks that occur in the bottom of a stream bed.

Column

A cylindrical cave formation that extends from the floor to the ceiling of a cave. Usually forms by a stalactite and stalagmite joining.

Competence

The largest particle that a stream can transport under certain flow and volume conditions.

Cone of ascension

A local rise in the water table formed at the bottom of a well. Usually salt water is rising upward toward the well hole.

Cone of depression

A local depression in the water table formed from pumping a well. It forms because water can't flow into the well as fast as it is removed from the well.

Cut bank

A steep river bank or small cliff formed on the outside bend of a river meander.

Delta

A deposit formed at the mouth of a river where it enters into another body of water.

Disappearing stream

A stream which either loses surface flow over time and eventually "disappears" or one which drains into a sinkhole and begins to flow underground.

Dissolved load

The chemical load of a stream. It can include dissolved rock components, pollutants, nutrients, and various ions.

Distributaries

On a river delta, the major stream splits into smaller streams just before it enters into a large body of water.

Entrenched meander

A bend or series of bends in a river that has formed a deep bedrock canyon.

Erosion

The process where rock and/or soil material is picked up and transported to another location.

Floodplain

A relatively flat area next to a stream onto which a flooding river will overflow.

Flowstone

A cave formation that coats walls, ceilings, and other flat areas of caves. Usually made of calcite (sometimes referred to as travertine limestone).

Fumaroles

Cracks, vents, or fissures where volcanic gases escape into the atmosphere.

Geyser

A fountain of pressurized hot water.

Groundwater

Water that is found below the surface of Earth.

Helictite

A type of cave formation that often has bizarre shapes.

Hot springs

Hot water that comes out of Earth.

Hydraulic action

A physical/mechanical weathering process caused by the force of rapidly flowing water.

Hydrologic cycle

The cyclical pattern where water moves from one reservoir (e.g., the oceans, atmosphere, surface waters, glaciers, and groundwater) to another.

Karst topography

A description of the surface of Earth when it has been severely modified by solution of the underlying carbonate rock. The surface will typically have disappearing streams, sinkholes, round lakes, and cave openings.

Meander scar

The remnants of a former bend in a river often evident from above due to color changes in the soil or vegetation. It can result from an oxbow lake being filled in with debris.

Meandering stream

A river that winds or bends back and forth across a floodplain in a series of large loop-like patterns.

Misfit stream

A stream that is quite small compared to the large valley that it flows in.

Mud pots

Similar to hot springs, but with mud instead of water. Often the mud will bubble as gases rise and escape from it.

Natural levees

Low ridges found along meandering streams. The ridges are formed during flooding as water spills out of a stream bank and deposits some of its load right next to the stream channel. Levees can also be man-made.

Oxbow lake

A crescent-shaped lake which is the remnant of a meandering stream bend. Sometimes occurs in the shape of a horse shoe.

Perched water table

A water table that is above the main water table.

Permeability

The ability of water (or other fluids) to flow through a rock.

Point bar

A deposit of sand or gravel that forms in the shallow, slowly moving water on the inside of a meander bend in a stream.

Porosity

The amount of empty space in a rock, usually expressed as a percentage.

River terrace

A bench or series of benches in a river valley that represent former floodplains that the river has abandoned.

Saltation

A process where particles (usually sand) bounce along a stream bed or a desert sand dune surface. When one sand grain hits the bottom, it usually stimulates other sand grains to bounce up into a current.

Sinkhole

A hole that develops in the surface of the ground due to the ceiling of an underground cavity collapsing.

Soda straw

A type of cave formation that hands from the ceiling of a cave and is hollow. Like a drinking straw, water can flow through the hollow interior of the formation.

Solution

Some rocks can be dissolved by various acids.

Speleothem

Any type of cave formation, usually made of travertine, or dense calcium carbonate.

Spring

When water flows out of the ground.

Spring deposit

When water flows out of the ground and leaves some type of chemical residue behind (usually travertine limestone or tufa).

Stalactite

A type of cave formation that hangs from the ceiling of a cave.

Stalagmite

A type of cave formation that grows from the floor of a cave.

Suspended load

Material (usually clay or silt) that is carried along in the moving current of a stream and does not settle out until the water stops moving.

Thermal features

Any type of hot groundwater phenomenon (springs, geysers, fumaroles, mud pots).

Travertine

A dense type of limestone (calcium carbonate) that usually forms in association with springs or cave deposits.

Tributaries

Smaller rivers that join into a larger river.

Tufa

A type of limestone usually associated with spring deposits that has significant cavities and small holes within it. It will often contain fossilized remains of organisms associated with the spring water (reeds, moss).

Unsaturated zone

A zone above the water table that is not completely full of water. Sometimes called the vadose zone.

Water table

The place underground where the unsaturated and saturated zones meet. It is typically not flat; it usually contours the surface of the ground above it.

Weathering

A mechanical or chemical process that breaks a larger rock down into smaller pieces or its chemical components.

Zone of aeration

Sometimes also called the vadose zone. Located above the water table.