A stream bed, often in a steep-sided valley, in an arid region that is dry except during the rainy season. The photo is from Wadi Degla in Northern Egypt.
A slight bend, uplift or subsidence of Earth's crust on a regional scale.
Wasting Natural Resources
Mineral resources that can be extracted by people but which can not be
readily replaced by the actions of people or nature. Oil, gas, coal, iron
ore, gold, stone, sand and gravel are examples.
The movement of water between the atmosphere, ground and surface water
bodies through the processes of evaporation, precipitation, infiltration, percolation, transpiration and runoff. Also known as the "hydrologic cycle".
An assessment of the physical, chemical and biological characteristics of water, especially how they relate to the suitability of that water for a particular use. In the photo a National Park Service employee conducts water quality monitoring using, hand-held meters, of a stream at Russell Cave National Monument.
The geographic area that contributes runoff to a stream. It can be outlined on a topographic map by tracing the points of highest elevation (usually ridge crests) between two adjacent stream valleys. The watershed of a large river usually contains the watersheds of many smaller streams. Also referred to as a "drainage basin".
A level beneath the Earth's surface, below which all pore spaces are filled with water and above which the pore spaces are filled with air. The top of the zone of saturation in a subsurface rock, soil or sediment unit.
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A long, level surface formed by wave erosion during a time when sea level was higher.
An interval of repetition in a wave-like disturbance. The distance between two successive crests or two successive troughs.
The value of natural gas at the mouth of the well.
Natural gas that contains hydrocarbons other than methane that are in the gaseous state in the high temperatures and pressures of the subsurface, but that condense into liquids as they flow from a well. These condensates include hydrocarbons such as pentane, butane, propane, hexane and others. They have commercial value and must be refined from the methane to make it a suitable fuel.
"Light opal" or "white opal" are terms used for an opal material with a white, yellow, or cream-colored body color. This is the most common body color for precious opal.
A removal of water from a surface or groundwater source for use.
Worked Over Well
A previously drilled hole that is reentered and treated to improve or initiate a flow of oil and or natural gas, without drilling additional footage.
An interest in a mineral property that entitles a party to a share of the mineral production, often subject to a royalty. The party is responsible for either carrying out or bearing the costs of exploration, development and production.