The rigid outer part of the earth, consisting of the crust and upper mantle.
Lithosphere
An actively forming region where two (or more)tectonic plates or fragments of the lithosphere move toward one another and collide.
Convergent Boundary
A linear feature that exists between two tectonic plates that are moving away from each other.
Divergent Boundary
A type of fault whose relative motion in predominately horizontal, in either a sinistral(left lateral) or dextral(right lateral) direction.
Transform Boundary
A small area or region with a relatively hot temperature in comparison to its surroundings.
Hot Spot
A long, narrow ditch.
Trench
The biggest crash scene on earth where boundaries mark the collision between two of the planet's tectonic plates.
Subduction Zone
The sideways and downward movement of the edge of a plate of the earth's crust into the mantle beneath another plate.
Subduction
The relatively thick part of the earth's crust that forms the large landmasses.
Continental Crust
The relatively think part of the earth's crust that underlies the ocean basins.
Oceanic Crust
Hot fluid or semi-fluid material below or within the earth's crust from which lava and other igneous rock is formed by cooling.
Magma
Hot molten or semi-fluid rock erupted from a volcano or fissure, or solid rock resulting from cooling of this.
Lava
An underwater mountain range, formed by plate tectonics.
Mid Ocean Ridge
A large elongated depression with steep walls formed by the downward displacement of a block of the earth's surface between nearly parallel faults or fault systems.
Rift Valley
A sudden and violent shaking of the ground, sometimes causing great destruction, as a result of movements within the earth's crust or volcanic action.
Earthquake
A mountain or hill, typically conical, having a crate or vent through which lava, rock fragments, hot vapor and gas are being or have been erupted from the earth's crust.
Volcano