chapter 8 // earth systems

core

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

mantle

layer of earth above core, containing magma

asthenosphere

layer of earth located in the outer part of the mantle, composed of semi-molten rock

lithosphere

outermost layer of Earth, including crust and mantle

crust

chemically distinct outermost layer of the lithosphere

hot spots

place where molten material from earth’s mantle reaches the lithosphere

plate techtonics

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

tectonic cycle

sum of hte processes that build up and break down the lithosphere

subduction

process of 1 crustal plate passing under another

divergent plate boundary

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

convergent plate boundary

area where plates move toward 1 another and collide

transform fault boundary

area where tectonic plates move sideways past each other

fault

fracture in rock caused by a movement of earth’s crust

seismic activity

frequency and intensity of earthquakes experienced over time

fault zone

large expanse of rock where a fault has occured

seafloor spreading

formation of new ocean crust as a result of magma pushing upward and outward form earth’s matle to the surface

epicenter

exact point on the surface of the earth directly above the location where rock ruptures during an earthquake

richter scale

measures the largest ground movement that occurs during an earthquake

the rock cycle

geologic cycle governing the constant formation, alteration, and destruction of rock material that results from tectonics, weathering, and erosin, etc.

igneous rock

formed directly above magma

intrusive igneous rock

forms when manga rises up and cools in a place underground

extrusive igneous rock

forms when magma cools aboveground

sedimentary rok

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

metamorphic rock

forms when any type of rock is subjected to high temp and pressure

physical weathering

mechanical breakdown of rocks and minerals. can be caused by water, wind, temp variations, or plants

chemical weathering

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

acid precipitation/rain

precipitation high in sulfuric acid and nitric acid from reactions between water vapor and sulfur and nitrogen oxides in the atmosphere

erosion

physical weathering

parent material

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

soil degradation

loss of some/all of a soil’s ability to support plant growth

soil horizons

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

O horizon

organic layer at the surface, composed of organic detritus in various stages of decomposition

A horizon/topsoil

frequently the top layer, a zone of organic material and minerals that have mixed together

E horizon

zone of leaching/eluviation, found in acidic soild under the O or A horizon

B horizon

composed mainly of mineral material with very little organic matter

C horizon

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

physical properties of soil

• texture of soil is determined by percentage of sand, silt, and clay

• permeability of soil is determined by its texture

chemical properties of soil

• cation exchange capacity (CEC)

• base saturation

cation exchange capacity (CEC)

ability of a particular soil to absorb and release cations

base saturation

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

crustal abundance

average concentration of an element in earth’s crust

ore

concentrated accumulation of minerals from which economically valuable materals can be extracted

metal

an element with properties that allow it to conduct electricity and heat energy

reserve

the known quantity of a resource that can be economically recovered

strip mining

removal of strips of soil and rock to expose ore

open-pit mining

uses a large visible pit int he ground

mountaintop removal

entire top of a mountain is removed with explosives

placer mining

process of looking for minerals, metals, and precious stones in river settlements

subsurface mining

mining technique used when the desired resouce is more than 100 m (328 ft) below the surface of the earth

mining spoils/tailings

unwanted waste material created during mining