Environmental Engineering Reference
In-Depth Information
Tidal wave
The semi-diurnal rise and fall of the ocean surface as the
tidal bulge
sweeps
around the global ocean.
Tide
The regular horizontal and vertical motion of the ocean surface in response to the
gravitational attraction of sun and moon, most noticeable at the coastline, where its
effects are usually amplified.
Tidewater glacier
A glacier which terminates in the sea, into which
glaciomarine
environment it discharges sediment, meltwater and
icebergs
.
Till
A coarse, generally unsorted and unstratified sediment deposited by glacier ice; its
bimodal character, with large
clasts
and a fine-grained matrix - described in the now
defunct term 'boulder clay' - reflects the indiscriminate power of glaciers.
Timberline
The upper altitudinal or latitudinal limit beyond which trees cannot normally
grow; locally, microclimate may sustain pockets of trees beyond the regional
timberline.
Time of rise
The time elapsed from the point at which discharge increases in response to
a precipitation event and the point of
peak discharge
.
Tolerance model
The model of succession in which the modification of a habitat by an
established species has little effect on other species, as changes in the composition of a
community are controlled by the life cycle of the plants.
Tombolo
A sand or gravel bar connecting an island with another land mass.
Top carnivore
The carnivore which occupies the highest position in a food web or
energy pyramid
.
Topoclimate
A local mesoclimate extending up to 250 m above a land surface, in which
regional climate is modified by topographic and slope factors such as aspect, shade,
exposure, etc.
Topographic climax
Climax vegetation maintained by topographic conditions
(exposure, soil hydrology or aspect).
Toppling failure
A rockfall involving a column of rock (or cohesive soil) whose centre
of gravity overhangs a pivot point; the column rotates outwards at its top before
overturning.
Tor
A residual rock pinnacle or pile on an elevated site, best developed in massive
crystalline rocks, and exposed by the
weathering
and
mass wasting
of surrounding
rock mass.
Trace element
An essential nutrient for plant growth but needed only in very small
quantities.
Trailing edge
The receding
passive margin
of continental crust with a distal
orogen
or
proximal rift escarpment, wide continental plain and shelf which influence coastal
development (cf.
leading edge
).
Transform fault
A large-scale fault between or within crustal plates, with displacement
wholly or mostly in the horizontal plane (see
strike-slip fault
).
Transform margin
A plate margin which coincides with and is guided by a
transform
fault
.
Transgression
The submergence of low-lying coastal land by rising sea level or land
subsidence and consequential landward shifts in each component of the littoral zone.
Transitional soils
An early term for intrazonal soils, i.e. soils whose profiles are
controlled by local factors of geology and topography.