APES Unit 4 - Chapter 8

A horizon

Frequently the top layer of soil, a zone of organic material and minerals that have been mixed together. Also known as topsoil.

Acid precipitation

Precipitation high in sulfuric acid and nitric acid from reactions between water vapor and sulfur and nitrogen oxides in the atmosphere. Also known as acid rain.

Asthenosphere

The layer of Earth located in the outer part of the mantle, composed of semi-molten rock.

B horizon

A soil horizon composed primarily of mineral material with very little organic matter.

Base saturation

The proportion of soil bases to soil acids, expressed as a percentage.

C horizon

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

Cation exchange capacity (CEC)

The ability of a particular soil to absorb and release cations.

Chemical weathering

The breakdown of rocks and minerals by chemical reactions, the dissolving of chemical elements from rocks, or both.

Convergent plate boundary

An area where plates move toward one another and collide.

Core

The innermost zone of Earth's interior, composed mostly of iron and nickel. It includes a liquid outer layer and a solid inner layer.

Crust

In geology, the chemically distinct outermost layer of the lithosphere.

Crustal abundance

The average concentration of an element in Earth's crust.

Divergent plate boundary

An area beneath the ocean where -tectonic plates move away from each other.

E horizon

A zone of leaching, or eluviation, found in some acidic soils under the O horizon or, less often, the A horizon.

Earthquake

The sudden movement of Earth's crust caused by a release of potential energy along a geologic fault and usually causing a vibration or trembling at Earth's surface.

Epicenter

The exact point on the surface of Earth -directly above the location where rock ruptures during an earthquake.

Erosion

The physical removal of rock fragments from a landscape or ecosystem.

Extrusive igneous rock

Rock that forms when magma cools above the surface of Earth.

Fault

A fracture in rock caused by a movement of Earth's crust.

Fault zone

A large expanse of rock where a fault has occurred.

Fracture

In geology, a crack that occurs in rock as it cools.

Horizon

A horizontal layer in a soil defined by distinctive physical features such as texture and color.

Hot spot

In geology, a place where molten material from Earth's mantle reaches the lithosphere.

Igneous rock

Rock formed directly from magma.

Intrusive igneous rock

Igneous rock that forms when magma rises up and cools in a place underground.

Lithosphere

The outermost layer of Earth, including the mantle and crust.

Magma

Molten rock.

Mantle

The layer of Earth above the core, containing magma.

Metal

An element with properties that allow it to conduct electricity and heat energy, and to perform other important functions.

Metamorphic rock

Rock that forms when sedimentary rock, igneous rock, or other metamorphic rock is subjected to high temperature and pressure.

Mining spoils

Unwanted waste material created during mining. Also known as tailings.

Mountaintop removal

A mining technique in which the entire top of a mountain is removed with -explosives.

O horizon

The organic horizon at the surface of many soils, composed of organic detritus in various stages of decomposition.

Open-pit mining

A mining technique that uses a large visible pit or hole in the ground.

Ore

A concentrated accumulation of minerals from which -economically valuable materials can be extracted.

Parent material

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

Physical weathering

The mechanical breakdown of rocks and minerals.

Placer mining

The process of looking for minerals, metals, and -precious stones in river sediments.

Plate tectonics

The theory that the lithosphere of Earth is divided into plates, most of which are in constant motion.

Reserve

In resource management, the known quantity of a resource that can be economically recovered.

Richter scale

A scale that measures the largest ground movement that occurs during an earthquake.

Rock cycle

The geologic cycle governing the constant formation, alteration, and destruction of rock -material that results from tectonics, weathering, and erosion, among other processes.

Seafloor spreading

The formation of new ocean crust as a result of magma pushing upward and outward from Earth's mantle to the surface.

Sedimentary rock

Rock that forms when sediments such as muds, sands, or gravels are compressed by overlying sediments.

Seismic activity

The frequency and intensity of earthquakes -experienced over time.

Soil degradation

The loss of some or all of a soil's ability to support plant growth.

Strip mining

The removal of strips of soil and rock to expose ore.

Subduction

The process of one crustal plate passing under another.

Subsurface mining

Mining techniques used when the desired -resource is more than 100 m (328 feet) below the surface of Earth.

Tailings

Unwanted waste material created during mining.

Tectonic cycle

The sum of the processes that build up and break down the lithosphere.

Topsoil

Frequently the top layer of soil, a zone of organic material and minerals that have been mixed together.

Transform fault boundary

An area where tectonic plates move sideways past each other.

Volcano

A vent in the surface of Earth that emits ash, gases, or molten lava.