Core
The innermost zone of the planet. It is largely made up of nickel and some iron. Heat from the Earth's core creates convection cells that drive the continuous change, creation, and renewal of Earth materials in the lithosphere.
Mantle
The zone in planet Earth that contains magma
Magma
Molten Rock
Asthenosphere
The outer part of the mantle, which is composed of semi-molten, ductile rock
Lithosphere
Includes the solid upper mantle and well as the crust. It is made up of several large and numerous smaller plates, which overlie convection cells in the asthenosphere. The lithosphere is broken into a number of plates. Oceanic plates lie primarily beneath
Crust
The chemically distinct outermost layer of the lithosphere. This is where soil is located. Soil is what makes life possible on the planet. The crust and overlying soil provide most of the chemical elements that comprise life
Hot Spots
Plates where molten material from the mantle reaches the lithosphere. It is caused by heat located in the Earth's outer core and mantle.
Theory of Plate Tectonics
This theory states that Earth's lithosphere is divided into plates, most of which are in constant motion.
Tectonic Cycle
The sum of the processes that build up and break down the lithosphere
Subduction
Where oceanic plates meet continental plates, old oceanic crust is pulled downward, beneath the continental lithosphere, and the heavier oceanic plate slides underneath the lighter continental plate.
Volcano
A vent in Earth's surface that emits ash, gases, and molten lava. Volcanoes are a result of hot spots.
Fault
A fracture in rock across which there is movement
Fault Zones
Large expanses of rock where movement has occurred. They form in the brittle upper lithosphere where two plates meet.
Earthquake
Earthquakes occur when the rocks of the lithosphere rupture unexpectedly along a fault. The plates can move up to several meters in just a few seconds. Earthquakes are a result of the movement of plates and their contact with each other.
Seismic Activity
Fault Zones are areas of seismic activity. One example is the San Andreas Fault in California, which is a transform fault.
Epicenter
The exact point on the surface of Earth directly above the location where the rock ruptures
Richter Scale
A measure of the largest ground movement that occurs during an earthquake
Rock Cyle
The constant formation and destruction of rock. The rock cycle is the slowest of all rock cycles
Minerals
Solid chemical substances with uniform structures that form under specific temperatures and pressures. Some examples of common minerals are pyrite, graphite, and halite.
Igneous Rocks
Rocks that form directly from magma. They are classified by their chemical composition as basaltic or granitic, and by their mode of formation as intrusive or extrusive. Basaltic rock is dark-colored rock that contains minerals with high concentrations of
Intrusive igneous rocks
Intrusive Igneous rocks form within the Earth as magma rises up and cools in place underground.
Extrusive Igneous Rocks
Extrusive Igneous Rocks form when magma cools above Earth's surface, as when it is ejected from a volcano or released by seafloor spreading.
Fractures
When rock cools, it is subject to stresses that cause it to break. Cracks occur in this way, known as fractures, can occur in any kind of rock.
Sedimentary Rocks.
These rocks form when sediments such as muds, sands, or gravels are compressed by overlying sediments. Sedimentary rock formation occurs over long periods when environments such as sand dunes, lake beds, or landslide-prone areas are buried and the overlyi
Metamorphic Rocks
Metamorphic Rocks form when sedimentary rocks, igneous rocks, or other metamorphic rocks are subjected to high temperatures and pressures. The pressures that form metamorphic rock cause profound physical and chemical changes in the rock. These pressures c
Physical Weathering
The mechanical breakdown of rocks and minerals. Physical weathering can be caused by water, wind, or variations in temperature such as seasonal freeze-thaw cycles. Coarse-grained rock formed by slow cooling or metamorphism tends of weather more quickly th
Chemical Weathering
The breakdown of rocks and minerals by chemical reactions, the dissolving of chemical elements from rocks, or both. It releases essential nutrients from rocks, making them available for use by plants and other organisms. Chemical weathering is most import
Acid Precipitation
Acid Rain is responsible for rapid degradation of old statues, gravestones, limestone, and marble. When it falls on soil, it can promote chemical weathering of certain minerals in the soil, releasing elements that may then be taken up by plants or leached
Erosion
The physical removal of rock fragments from a landscape or ecosystem. Erosion is the result of two mechanisms. Wind, water, and ice transport soil and other Earth materials by downslope creep under the force of gravity. Living organisms, such as animals t
Deposition
The accumulation or depositing of eroded material such as sediment fragments, or soil
Soil
A mix of geologic and organic components.
Parent Material
The rock material underlying it from which its inorganic components are derived. Different soil types arise from different parent materials.
Climate
Soils do not develop well when temperatures are below freezing because decomposition of organic matter and water movement are both extremely slow in frozen or nearly frozen soils. Climate also has an indirect effect on soil formation through its influence
Topography
Topography is the surface slope and arrangement of a landscape. It is the third factor that influences soil formation. Soils that form on steep slopes are constantly subjected to erosion and more drastic mass movements of material such as landslides. Soil
Organisms
Plants remove nutrients from soil and excrete organic acids that speed chemical weathering. Animals that tunnel or burrow, such earthworms, gophers, and voles, mix the soil, distributing organic and mineral matter uniformly throughout.
Time
The amount of time a soil has spent developing is important in determining its properties. As soils age, they develop a variety of characteristics. Continual inputs of organic matter for hundreds of thousands of years have made soils deep and fertile. Oth
Horizons
Layers. The specific composition of those horizons depends largely on climate, vegetation, and parent material
O Horizon
At the surface of many soils is a layer of organic detritus and animal bodies, all in various stages of decomposition
A Horizon
This is also known as topsoil. It is a zone of organic material and minerals that have been mixed together
E Horizon
A zone of leaching, or eluviation. It forms under the O Horizon or the A Horizon. When present, it always occurs above the B Horizon. When the E Horizon is present, iron, aluminum, and dissolved organic acids from the overlying horizons are transported th
B Horizon
This is commonly known as subsoil. It is composed primarily of mineral material with very little organic matter.
C Horizon
The least weathered soil horizon, always occurs beneath the B Horizon. The C Horizon is similar to the parent material.
Texture
The texture of a soil is determined by percentages of sand, silt, and clay it contains. Soil texture can have a strong influence on how the physical environment responds to environmental pollution.
Porosity
How quickly soil drains. This depends on the texture of the soil. Sand has the highest porosity, because sand particles are the largest. Clay particles has the the lowest porosity, because it is the smallest of the three components. Silt particles are int
Cation Exchange Capacity
The ability of a soil to absorb and release cations. The overall CEC of a soil is a function of the amount and types of clay particles present. Soils with high CECs have the potential to provide essential cations to plants and are desirable for agricultur
Base Saturation
A measure of the proportion of soil bases to soil acids, expressed as a percentage.
Soil degradation
The loss of some or all of the ability of soils to support plant growth. One of the major causes of soil degradation is soil erosion which occurs when topsoil is disturbed or vegetation is removed, allowing the soil to be eroded by water or wind.
The Mining Law of 1872`
This is a United States federal law that authorizes and governs prospecting and mining for economic minerals. It was passed to promote the development and settlement of publicly-owned lands in the western United States.
The Surface Mining Control and Reclamation Act of 1977
The primary federal law that regulates the environmental effects of coal mining in the United States.
Smelting
extract (metal) from its ore by a process involving heating and melting.