Q and R Index Glossary geology Science
Q and R Index Glossary geology Science
Quartzose sandstone
(1) A quartz arenite. (2) A clean quartz sandstone, less pure than a quartz arenite, that may contain a moderate amount of other detrital minerals and/or calcite cement.
Quarry
A surface mine usually for the extraction of construction stone.
Quartz
One of the most abundant minerals in the earth's crust. Has a chemical composition of SiO2 and a hardness of seven. One of the index minerals in Moh's Hardness Scale. Occurs in sedimentary, metamorphic and igneous rocks.
Quartz Arenite
A sandstone consisting of at least 95% quartz.
Quaternary Sector
That portion of a region's economy devoted to informational and idea-generating activities (e.g., basic research, universities and colleges, and news media).
Quartzose
An adjective used in reference to a rock that is composted primarily of quartz.
quaternary ice age
An ice age that began approximately 1.6 million years ago and continues to the present time.
quaternary period
The second period of the Cenozoic Era, beginning two to three million years ago and continuing to the present time.
quick clay
Sediment that sets off a sudden mudflow by changing rapidly from solid to liquid form, as after an earthquake, an explosion, or thunder
Radial Drainage
A drainage pattern in which stream channels run away from a central
Radiolarian
A group of one-celled marine animals with a siliceous skeleton that occupies shallow portions of the water column. Radiolarians have a range from Cambrian to present.
Radiolarian Ooze
A deep-sea pelagic sediment that contains at least 30% siliceous radiolarian remains.
Rating Curve
A plot that shows the relationship between the stage and discharge (streamflow) of a specific stream at a specific location. It is customary to plot stream stage on the y-axis of the plot and discharge on the x-axis. The resulting relationship is normally a curve. Rating curves can be used to estimate discharge (which is time consuming and expensive to measure) using a single stage measurement (which can be collected with automatic equipment). The principle of a rating curve enables hydrologists to monitor the discharge of many streams simultaneously once gages have been placed to collect and report the stage of the stream.
Reaction Series
A series of interactions between a melt and mineral crystals in contact with the melt. In a reaction series the first formed crystals (highest temperature minerals) react with the melt to produce a new mineral.
Radiative transfer
One mechanism for the movement of heat, in which it takes the form of long-wavelength infrared radiation.
Radiolarite
The lithified sedimentary rock formed from radiolarian ooze.
Ray
A linear landform of the lunar surface emanating from a large crater and extending as much as 100 kilometers outward, probably consisting of fine ejecta thrown out by the impact of a meteorite.
Replacement deposit
A deposit of ore minerals by hydrothermal solutions that have first dissolved the original mineral to form a small cavity.
Respiration
The chemical reaction by which carbohydrates are oxidized and by which all animals and plants convert their food into energy. Carbon dioxide is released and oxygen used up.
Reversible reaction
A chemical reaction which can proceed in either direction, depending on the concentration of reacting materials.
Rheidity
(1) The ability of a substance to yield to viscous flow under large strains. (2) One thousand times the time required for a substance to stop changing shape when stress is no longer applied.
Rift valley
A fault trough formed in a divergence zone or other area of tension.
Ring dike
A dike in the form of a segment of a cone or cylinder, having an arcuare outcrop.
Ripple
A very small dune of sand or silt whose long dimension is formed at right angles to the current. River order: See Stream order.
Recharge
Water added to an aquifer or other water body. An aquifer is recharged by precipitation in an area where the aquifer has a porous connection to the surface.
Recharge Area
The geographic area where water infiltrates into the ground and enters an aquifer..
Recrystallization
A solid state reaction in which the atoms of existing crystals within a rock are reorganized in response to heat and/or pressure. The recrystallized mineral grains are typically larger in size than the original crystals.
Rectangular Drainage
A drainage pattern in which stream channels develop within a large-scale network of intersecting joints. This drainage pattern is characterized by right-angle bends in the channels of streams and streams that intersect at right angles.
Recumbent Fold
An overturned fold that has two limbs which are nearly horizontal.
Refraction
The bending of a seismic wave as it enters a material of different density, or, the bending of a beam of light as it enters a material of different refractive index.
Regolith
A general term used in reference to unconsolidated rock, alluvium or soil material on top of the bedrock. Regolith may be formed in place or transported in from adjacent lands.
Regression
A retreat of the sea from land areas. Possible causes include a drop in sea level or uplift.
Relief
Variations in the height and slope of Earth's surface. Also used in reference to the vertical difference between the highest and lowest elevations of an area.
Remote Sensing
The collection of information about an object or area from a distance. Methods employed include photography, radar, spectroscopy and magnetism.
Replacement
The dissolving or disintegration of one material followed by precipitation of a new material in its place.
Rail Gauge
The distance between the two rails of a railroad.
Rainshadow
An area of diminished precipitation on the lee (downwind) side of a mountain or mountain range.
radiometric dating
The process of using relative proportions of parent to daughter isotopes in radioactive decay to determine the age of a given rock or rock stratum.
rain shadow effect
The result of the process by which moist air on the windward side of a mountain rises and cools, causing precipitation and leaving the leeward side of the mountain dry.
reef
A ridge that forms in clear, moderately salty seawater near the shoreline and is composed of the carbonate remains of algae, sponges, and especially corals.
regional metamorphism
Metamorphism that affects rocks over vast geographic areas stretching for thousands of square kilometers.
relative dating
The fixing of a geologic structure or event in a chronological sequence relative to other geologic structures or events. See also absolute dating.
reserve
A known resource that can be exploited for profit with available technology under existing political and economic conditions.
recycled water
water that is used more than one time before it passes back into the natural hydrologic system.
reservoir
a pond, lake, or basin, either natural or artificial, for the storage, regulation, and control of water.
returnflow
irrigation water that is applied to an area and which is not consumed in evaporation or transpiration and returns to a surface stream or aquifer.
reverse osmosis
(1) (Desalination) The process of removing salts from water using a membrane. With reverse osmosis, the product water passes through a fine membrane that the salts are unable to pass through, while the salt waste (brine) is removed and disposed. This process differs from electrodialysis, where the salts are extracted from the feedwater by using a membrane with an electrical current to separate the ions. The positive ions go through one membrane, while the negative ions flow through a different membrane, leaving the end product of freshwater.
(2) (Water Quality) An advanced method of water or wastewater treatment that relies on a semi-permeable membrane to separate waters from pollutants. An external force is used to reverse the normal osmotic process resulting in the solvent moving from a solution of higher concentration to one of lower concentration.
riparian water rights
the rights of an owner whose land abuts water. They differ from state to state and often depend on whether the water is a river, lake, or ocean. The doctrine of riparian rights is an old one, having its origins in English common law. Specifically, persons who own land adjacent to a stream have the right to make reasonable use of the stream. Riparian users of a stream share the streamflow among themselves, and the concept of priority of use (Prior Appropriation Doctrine) is not applicable. Riparian rights cannot be sold or transferred for use on nonriparian land.
river
A natural stream of water of considerable volume, larger than a brook or creek.
runoff
-(1) That part of the precipitation, snow melt, or irrigation water that appears in uncontrolled surface streams, rivers, drains or sewers. Runoff may be classified according to speed of appearance after rainfall or melting snow as direct runoff or base runoff, and according to source as surface runoff, storm interflow, or ground-water runoff.
-(2) The total discharge described in (1), above, during a specified period of time.
-(3) Also defined as the depth to which a drainage area would be covered if all of the runoff for a given period of time were uniformly distributed over it.
rtesian water
ground water that is under pressure when tapped by a well and is able to rise above the level at which it is first encountered. It may or may not flow out at ground level. The pressure in such an aquifer commonly is called artesian pressure, and the formation containing artesian water is an artesian aquifer or confined aquifer.
reservoir rock
A permeable rock containing oil or gas.
reverse fault
A dip-slip fault marked by a hanging wall that has moved upward relative to the footwall. Reverse faults are often caused by the convergence of lithospheric plates.
radioactive decay
The process of spontaneously emitting protons and neutrons that transforms one isotope into another.
Richter scale
A logarithmic scale that measures the amount of energy released during an earthquake on the basis of the amplitude of the highest peak recorded on a seismogram. Each unit increase in the Richter scale represents a 10-fold increase in the amplitude recorded on the seismogram and a 30-fold increase in energy released by the earthquake. Theoretically the Richter scale has no upper limit, but the yield point of the Earth's rocks imposes an effective limit between 9.0 and 9.5.
riprap
A pile of large, angular boulders built seaward of the shoreline in order to prevent erosion by waves or currents. See also seawall.
rock
A naturally formed aggregate of usually inorganic materials from within the Earth.
rock-forming mineral
One of the twenty or so minerals contained in the rock that composes the Earth's crust and mantle
rubidium-strontium dating
A form of radiometric dating that relies on the 47-billion-year half-life of radioactive isotopes of rubidium, which decay into isotopes of strontium, to determine the age of rocks in which strontium is present. Rubidium-strontium dating is used for rocks that are at least 10 million years old, deep-Earth plutonic rocks, and Moon rocks.
Region
An area having some characteristic or characteristics that distinguish it from other areas. A territory of interest to people and for which one or more distinctive traits are used as the basis for its identity.
resource
Anything that is both naturally occurring and of use to humans.
- A mineral or fuel deposit, known or not yet discovered, that may be or become available for human exploitation.
Riparian Rights
The rights of water use possessed by a person owning land containing or bordering a water course or lake.
Riverine
Located on or inhabiting the banks or the area near a river or lake.
Retrograde Metamorphism
Mineral changes within a rock that are caused by adjustments to conditions of reduced temperature and pressure.
Rhyolite
The fine-grained volcanic or extrusive rocks that is equivalent in composition to granite. Normally white, pink or gray in color.
Richter Magnitude Scale
A scale that is used to compare the strength of earthquakes based upon the amount of energy released. The scale is logarithmic and an arbitrary earthquake was used as a starting point for creating the scale. As a result it is a continuous scale with no upper limit and negative numbers possible for very small earthquakes. An upper limit of approximately 9.0 is suspected as earth materials will most likely fail before storing enough energy for a larger magnitude earthquake.
Ridge(Mid-Ocean)
An elevated area of the sea floor in the center of an ocean basin with rugged topography, a central rift-valley and recurring seismic activity. Ridges generally stand about 1000 meters to 3000 meters above the adjacent ocean floor and are about 1500 kilometers in width.
Right-Lateral Fault
A fault with horizontal movement. If you are standing on one side of the fault and look across it, the block on the opposite side of the fault has moved to the right. (Also see Left-Lateral Fault.)
Rip Current
A strong, narrow current of high velocity and short duration that flows seaward through the breaker zone. Caused when a build up of water pushed onto the beach by winds and waves returns seaward.
Ripple Marks
A series of parallel or sub-parallel ridges in sand or sediment that is caused by the rhythmic or directional movement of wind or water.
Rock Cycle
All rock at or near Earth's surface is being modified by the processes of metamorphism, melting, crystallization, lithification and weathering. These processes move rock material through the states of metamorphic rock, igneous rock, sedimentary rock, melts and sediment. The natural and continuous cycling of rock materials through these states is known as the rock cycle.
Rock Flour
Finely pulverized rock material of silt or smaller size produced by abrasion at the base of a glacier.
Rock Glacier
A mass of rock material, cemented together by ice, that flows down a slope under the force of gravity much like the motion of a glacier.
Rockslide
A type of mass wasting in which a large volume of rock debris slides down a slope under the influence of gravity.
Rupture Strength
The maximum amount of stress that a material can sustain without failure.