Vast, boreal forests of small, widely spaced trees typical of the subpolar climate.
talus slope
A pile of angular rock fragments formed at the base of a cliff or mountain.
temperature
A physical property of matter that expresses how hot or cold it is.
temperature gradient
The change in temperature with distance.
tension
Stresses that pull material in opposite directions.
tephra
Fragments of material produced in a volcanic eruption.
terminal moraine
Glacial till dumped at the furthest point reached by a glacier.
terrae
The light parts of the Moon’s surface, composed of high crater rims.
terrestrial planets
The solid, dense, rocky planets that are the same as the inner planets.
theory
A hypothesis that has been repeatedly tested that has no significant evidence against it.
thermal pollution
Water pollution created by adding heat to water.
thermohaline circulation
Temperature and salinity (density) driven currents that drive deep ocean circulation.
thermometer
A device that measures temperature.
thermosphere
The outer atmosphere where gases are extremely thinly distributed.
thrust
The forward force produced by gases escaping from a rocket engine.
thrust fault
A reverse fault in which the dip of the fault plane is nearly horizontal.
thunder
The loud clap produced by lightning.
thunderstorm
Storms caused by upwelling air; cumulonimbus clouds, thunder, and lightning.
tidal range
The difference between the high and low tide in a day.
tide
The regular rising and falling of Earth’s surface waters twice a tidal day as a result of the Moon’s and Sun’s gravitational attraction.
timber
Trees that are cut for wood to be used for building or some other purpose.
topographic map
A map that shows elevations above sea level to indicate geographic feature.
topography
Height of a feature relative to sea level.
topsoil
The A horizon; the most fertile layer with humus, plant roots and living organisms.
tornado
Violently rotating funnel cloud that grows downward from a cumulonimbus cloud.
trace fossil
Evidence of the activity of an ancient organism; e.g. tracks, tubes, and bite marks.
transform fault
An earthquake fault; one plate slides past another.
transform plate boundary
The type of plate boundary where two plates slide past one another.
transpiration
The release of water vapor into the air through the leaves of plants.
transported soil
Soil that forms from weathered components transported to a different area.
travertine
Beautiful deposit of calcium carbonate that forms around hot springs.
tree ring
Rings of wood equaling one year of tree growth in a tree trunk.
trench
A deep gash in the seafloor; the deepest places on Earth.
tributary
The smaller of two streams that join together to make a larger stream.
trophic level
Energy levels within a food chain or food web.
tropical
A climate that is warm and humid.
tropical depression
A low pressure cell that rises in the tropics; thunderstorms arise here.
tropical rainforest
A warm, wet biome with abundant broadleaf evergreen trees and large biodiversity.
troposphere
The lowermost layer of the atmosphere; temperature decreases with altitude.
trough
The lowest point of a wave.
tsunami
An enormous wave generated by vertical movement of the ocean floor during an underwater earthquake; tsunamis can also be caused by volcanic eruptions, landslides, or meteorite impacts. A deadly set of waves can rise high on a beach and travel far inland.
tundra
The treeless area of the arctic with very cold, harsh winters.