Environmental Engineering Reference
In-Depth Information
Weathering solution
Solution containing metallic ions and silica which is produced
during weathering.
Wedge slide
Sliding failure of a rock wedge bounded by two release surfaces where two
planar discontinuities
intersect; the angle of intersection must be greater than the
internal friction angle of the mass but less than the parent slope angle.
Wetted perimeter
The length of a river channel covered by water at a particular point
and water depth; an important component of the measure of
hydraulic radius
and
efficiency
.
White alkali soils
A popular term for solonchaks.
White box
A system in which a detailed knowledge of all the internal structure is
identified; it is rarely achieved, except in the simplest of systems.
Wildfire
A fire started by humans either by accident or for malicious reasons.
Wilson cycle
The alternative name for the
supercontinental
cycle, named after its
proponent, J. Tuzo Wilson, during the 1960s.
Wilting point
The moisture content of soil at which there is insufficient water to
maintain the turgor of the plant.
Wind stress
The force exerted by wind per unit area on an adjacent surface.
Windstorm
A violent cold-air gravity flow off the eastern Rocky Mountains in winter,
stimulated by temperature inversion over snow.
Xerophyte
A plant adapted to grow in arid habitats.
Xerosere
A
primary succession
which starts on a surface suffering from drought.
Yardang
An exposed rock surface abraded into a streamlined shape by windblown sand.
Younger Dryas
A European term for the climatic deterioration and mountain glaciation
c
. 11,000-10,000 BP, known in Britain as the
Loch Lomond Stadial
.
Zeolite
The lowest grade of metamorphic rock, formed at relatively low lithospheric
pressures and temperatures.
Zonal
Soils occurring in extensive zones on a world scale.
Zone of soil formation
The upper part of the zone of
weathering
where
soil-forming
processes
are most active.
Zone of weathering
The upper part of the lithosphere where
weathering
processes are
operating at a maximum.
