APES Unit 4 Vocab

earth's core

In geology, the central region of the Earth; it extends fourteen hundred to eighteen hundred miles from the Earth's center. Note: The core is made primarily of iron and nickel and has two parts — an inner solid core and an outer liquid core.

earth's mantle

The region of the interior of the Earth between the core (on its inner surface) and the crust (on its outer). Note: The mantle is more than two thousand miles thick and accounts for more than three-quarters of the volume of the Earth.

magma

hot fluid or semifluid material below or within the earth's crust from which lava and other igneous rock is formed by cooling.

asthenosphere

the upper layer of the earth's mantle, below the lithosphere, in which there is relatively low resistance to plastic flow and convection is thought to occur.

lithosphere

the rigid outer part of the earth, consisting of the crust and upper mantle.

crust

the outer layer of the Earth

plate tectonic cycle

The Plate Tectonic Cycle refers to the movement of large portions of the earth's crust in what is termed "plates." The boundaries of these plates are generally defined by the occurrence of volcanoes and earthquakes.

rock cycle

an idealized cycle of processes undergone by rocks in the earth's crust, involving igneous intrusion, uplift, erosion, transportation, deposition as sedimentary rock, metamorphism, remelting, and further igneous intrusion.

soil formation

The creation of soil and its layers.

plate tectonics

the structure of the earth's crust and many associated phenomena as resulting from the interaction of rigid lithospheric plates that move slowly over the underlying mantle.

Pangaea

the hypothetical landmass that existed when all continents were joined, from about 300 to 200 million years ago.

oceanic plate

A thick mass of igneous rock which lies under the ocean floor.

continental plate

Thick continental crust.

subduction zone

A subduction zone is the biggest smash-up on Earth, marking the collision between two of the planet's tectonic plates, the pieces of crust that slowly move across the surface over millions of years. When two tectonic plates meet, one may slide underneath the other, curving down into the mantle.

divergent plate boundary

In plate tectonics, a divergent boundary or divergent plate boundary (also known as a constructive boundary or an extensional boundary) is a linear feature that exists between two tectonic plates that are moving away from each other.

seafloor spreading

the formation of new areas of oceanic crust, which occurs through the upwelling of magma at midocean ridges and its subsequent outward movement on either side.

convergent plate boundary

In plate tectonics, a convergent boundary, also known as a destructive plate boundary (because of subduction), is an actively deforming region where two (or more) tectonic plates or fragments of the lithosphere move toward one another and collide.

transform fault boundary

A transform fault or transform boundary, also known as conservative plate boundary since these faults neither create nor destroy lithosphere, is a type of fault whose relative motion is predominantly horizontal in either sinistral or dextral direction.

fault

an extended break in a body of rock, marked by the relative displacement and discontinuity of strata on either side of a particular surface.

epicenter

the point on the earth's surface vertically above the focus of an earthquake.

ring of fire

the linear zone of seismic and volcanic activity that coincides in general with the margins of the Pacific Plate.

rock cycle

a continuous process by which rocks are created, changed from one form to another, destroyed, and then formed again.

igneous rock

Rocks formed by the cooling and solidifying of molten materials. Igneous rocks can form beneath the Earth's surface, or at its surface, as lava.

Note: Granite, solid volcanic lava, and basalt are examples of igneous rock.

sedimentary rock

Rock that has formed through the deposition and solidification of sediment, especially sediment transported by water (rivers, lakes, and oceans), ice (glaciers), and wind. Sedimentary rocks are often deposited in layers, and frequently contain fossils.

Note: Limestone and shale are common sedimentary rocks.

metamorphic rock

Rock that was once one form of rock but has changed to another under the influence of heat, pressure, or some other agent without passing through a liquid phase.

weathering

the various mechanical and chemical processes that cause exposed rock to decompose; there are two types: chemical and mechanical weathering.

erosion

the process by which the surface of the earth is worn away by the action of water, glaciers, winds, waves, etc.

soil

the portion of the earth's surface consisting of inorganic and organic material that provides the opportunity for growth or development.

deposition

the action of depositing something.

parent material

Parent material is the geologic material from which soil horizons form.

soil horizons

A soil horizon is a layer generally parallel to the soil surface, whose physical characteristics differ from the layers above and beneath. Each soil type usually has three or four horizons. Horizons are defined in most cases by obvious physical features, chiefly colour and texture.

o horizon

O horizons: are soil layers with a high percentage of organic matter. Typically within a woodland area there are three distinct organic layers: one of leaves, pine needles and twigs (Oi); underlain by a partially decomposed layer (Oe);and then a very dark layer of well decomposed humus (Oa).

a horizon

the topsoil in a soil profile.

b horizon

the subsoil in a soil profile.

c horizon

the layer in a soil profile below the B horizon and immediately above the bedrock, consisting chiefly of weathered, partially decomposed rock.

e horizon

A mineral horizon in the upper part of the soil. Typically present only in forested areas it underlies an O or A horizon. It is a light colored, leached horizon.

porosity

the ratio, expressed as a percentage, of the volume of the pores or interstices of a substance, as a rock or rock stratum, to the total volume of the mass.

soil degradation

the decline in soil quality caused by its improper use, usually for agricultural, pastural, industrial or urban purposes. Soil degradation is a serious global environmental problem and may be exacerbated by climate change. It encompasses physical, chemical and biological deterioration.

tragedy of the commons

An economic problem in which every individual tries to reap the greatest benefit from a given resource. As the demand for the resource overwhelms the supply, every individual who consumes an additional unit directly harms others who can no longer enjoy the benefits.

maximum sustainability yield

the maximum use that a renewable resource can sustain without impairing its renewability through natural growth or replenishment.