Environmental Engineering Reference
In-Depth Information
Hypsithermal
The 'climatic optimum' or period of highest global mean annual
temperature, between 8000 and 5000 years ago, during the
Holocene
or current
temperate stage.
Ice lens
A discrete, sub-surface layer in permafrost composed solely or mostly of
ground
ice
.
Ice sheet
A large, subcontinental- or continental-scale glacier of tabular shape which
buries all or most of the land surface.
Ice shelf
The floating portion of the margins of an
ice sheet
which, owing to the absence
of basal shear stress, spreads and thins over the sea surface.
Ice wedge
A mass of
ground ice
forming a vertical wedge in desiccation/contraction
cracks.
Iceberg
A block of ice which has become detached from a floating glacier or
ice shelf
.
Icefall
A steep, rapidly flowing and heavily crevassed glacier segment moving by
extending
or
surging
flow.
Icehouse
An uncommon condition in which Earth's average global temperature may be
nearer to that predicted by radiation laws by virtue of the presence and
autocatalytic
consequences of large ice sheets and frozen ocean surfaces.
Igneous
Of molten, partly molten or
magmatic
nature and origin.
Ignimbrite
The cooled and lithified product of a volcanic
ash flow
, also known as an
ash-flow tuff
.
Inceptisol
A soil order (USDA classification) characterized by the alteration or removal
of minerals other than carbonates or amorphous silica.
Incised meanders
The entrenched bedrock channels of old river meanders after
rejuvenation
.
Incision
The erosion of a narrow, bedrock river channel by vigorous fluvial downcutting.
Indentation tectonics
Crustal deformation caused by the penetration of one continental
plate by another and involving head-on compression, lateral extension and rotation in
the affected crust.
Individualistic communities
The concept that
plant communities
represent an
assemblage of plant species with overlapping environmental requirements which arise
because of random propagule availability.
Infiltration
The process by which water enters a soil through pores or cracks at the
surface from
precipitation
,
depression storage
or
overland flow
.
Infiltration capacity
The maximum rate at which water may infiltrate soil or rock.
Infiltration rate
The rate at which water added to the surface can enter the soil.
Information theoretic index
A measure of ecological diversity derived from the theory
of information (e.g. the Shannon index).
Inhibition model
The model of succession in which changes in floristic composition are
prevented until an established species dies out.
Input
The flow of energy and matter into a system.
Inselberg
A residual hill in massive, resistant rock which has survived the
weathering
and stripping of adjacent rock mass through its superior strength.
Inshore
The shallow-water coastal zone below the low-water mark in which waves
shoal
.
Insolation
A contraction of
in
coming
sol
ar radi
ation
. It refers to the short-wave part of
the solar energy input.
