APES - Unit 4 Vocabulary Part 1

A horizon

topsoil

B horizon

subsoil

C horizon

the least-weathered soil horizon, which always occurs beneath the B horizon and is similar to the parent material

CEC (cation exchange capacity)

the ability of a particular soil to absorb and release cations

chemical weathering

the process that breaks down rock through chemical changes

convergent

a tectonic plate boundary where two plates collide, come together, or crash into eachother

divergent

an area beneath the ocean where tectonic plates move away from each other

E horizon

the zone of leaching that forms under the O horizon or, less often, the A horizon

epicenter

the point on the earth’s surface directly above the focus of an earthquake

erosion

processes by which rock, sand, and soil, are broken down, and carried away (i.e. weathering, glaciation)

hot spot

an area where magma from deep within the mantle melts through the crust above it

humus

material formed from decaying leaves and other organic matter

igneous rocks

a type of rock that forms from the cooling of molten rock at or below the surface

lithosphere

a rigid layer made up of the uppermost part of the mantle and the crust

metamorphic rocks

a type of rock that forms from an existing rock that is changed by the heat, pressure, or chemical reactions

O horizon

the top layer of the surface containing inorganic solids, decaying organic matter, and living organisms

parent material

the rock material from which the inorganic components of a soil are derived

permeability

how easily substances can move through something

physical weathering

the mechanical breakdown of rocks and minerals

saturation point

the stage at which something can no longer hold more (usually water)

seafloor spreading

the process that creates new sea floor as plates move away from each other at the mid-ocean ridges

sedimentary rocks

a type of rock that forms when particles from other rocks or the remains of the plants and animals are pressed and cemented together

soil degradation

the loss of some air of a soil’s ability to support plant growth

subduction

the process by which oceanic crust sinks beneath a deep-ocean trench and back into the mantle at a convergent plate boundary

transform fault

boundary between two plates that are sliding past each other