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AP Enviro Sci 2013

Continental Crust

the portion of the earth's crust that primarily contains granite, is less dense than oceanic crust, and is 20-50 km thick

Oceanic Crust

The portion of Earth's crust that is usually below the oceans, thinner and higher in density than continental crust and made of basalt

Mohorovic Discontinuity "Moho"

boundary between the Earth's crust and mantle


The layer of hot, solid material between Earth's crust and core.


composed mostly of iron and is hot molten, under extreme pressure

Continental Drift Theory

Alfred Wegner, 1915, theory that states that the gradual shifting of Earth's plates causes continents to change their global positions over time

Seafloor Spreading Theory

dating of the rocks indicated that farther away from the ridge, the rocks became older, the crust was created at volcanic rift zones

Subduction zones

areas on the earth where two tectonic plates move and meet towards each other, one sliding underneath the other and moving down into the mantle .

Transform Boundaries

Plates slide past each other (ie The San Andreas Fault)

Divergent Boundaries

Plates slide apart from the othere with the space that was created being filled with molten magma from below (ie East African Great Rift Valley)

Convergent Boundaries

Plates slide toward each other forming either a subduction zone or an orogonic belt (ie Cascade Mountain Range)

Orogonic belt

if two plates collide and compress

Two oceanic plates converge-->

they create an island arc, curved chain of volcanic islands rising from the deep seafloor and near a continent. (ie Aleutian Islands by Alaska)

Two continental plates collide-->

mountain ranges are created as the colliding crust is compressed and pushed upwards (ie Himalayas)

Richter scale

a logarithmic scale of 1 to 10 used to express the energy released by an earthquake recorded by a seismograph, compares amplitudes of waves on a seismograph really

Body waves

seismic waves that travel through the interior of Earth

S waves

body waves that are produced when material moves either vertically or horizontally and travel only within the uppermost layers of earth

P waves

body waves that travel through Earth and are caused by expansion and contraction of bedrock

Severity of an earthquake depends on...

1.) the amount of potential energy that has been stored
2.) the distance the rock mass moved when the energy was released
3.) how far below the surface the movement occurred
4.) the makeup of the rock material


series of waves created when a body of water is rapidly displaced usually by an earthquake, can be devastating, subduction-zone related earthquakes lead to most tsunamis, rarely form near divergent boundaries, small wave height offshore, long wavelength, pass unnoticed at sea


classified as: intermittent, dormant, or extinct; most occur at subduction zones and mid-oceanic ridges, others occur at hot spots (areas of plumes of magma come close to the surface), volcanoes release sulfur dioxide, hydrogen chloride, carbon dioxide, and steam; eruption's particles increases average temperature and contributes to acid rain

Volcanic Eruptions

occur when pressure within a magma chamber forces molten magma through a conduit pope and out a vent at the top of the volcano, correlation exists between seismic and volcanic activity

Factors that affect solar energy at Earth's surface

Earth's rotation, tilt of Earth's axis, and atmospheric conditions

Seasons are NOT caused by

Earth's distance from the sun

Soil's formation dependent on

parent material, climate, living organisms, topography

O Horizon

Surface Litter: leaves and partially decomposed organic debris, may be very thick in deciduous forests and very thin in tundra and desert

A Horizon

Topsoil: Organic Matter (humus), living organisms, inorganic minerals. the topsoil is typically very thick in grasslands

E Horizon

Zone of leaching: dissolved and suspended materials move downward

B Horizon

Subsoil: tends to be yellowish in color due to the accumulation of iron, aluminum, humic compounds, and clay leached down from the A and E horizons, can be rich in nutrients in areas where rainwater leeched nutrients from the topsoil

C Horizon

Weathered parent material: parially broken-down inorganic materials


very fine particles, compacts easily, forms large, dense clumps when wet, low permeability to water; therefore, upper layers become waterlogged


coarse particles, consists of rock fragments


about equal mixtures of clay, sand, silt, and humus, rich in nutrients, holds water but does not become waterlogged


sedimentary material coarser than silt, water flows through too quickly for most crops, good for crops and plants requiring low amounts of water


sedimentary material consisting of very fine particles between the size of sand and clay, easily transported by water

Soil Food Web

First trophic level: photosynthesizers
Second trophic level: decomposers, mutualists, pathogens, parasites, root-feeders
Third trophic level: shredders, predators, grazers
Fourth trophic level: higher level predators
Fifth and higher: higher level predators

Organic Fertilizer

three common forms: animal manure, green manure, and compost; improves water-holding capacity of soil; helps to prevent erosion

Inorganic Fertilizer

Does not add humus to the soil, resulting in less ability to hold water and support living organisms (earthworms, beneficial bacteria, and fungi)
Lovers oxygen content of soil thereby keeping fertilizer from being taken up efficiently
Supplies only a limited number of nutrients (usually nitrogen and phosphorous)
Requires large amounts of energy to produce, transport and apply
Releases nitrous oxide--a green house gas

Causes of soil erosion

flowing water, wind, and human activity (cultivating inappropriate land, burning of native vegetation, deforestation, and construction)

Poor agricultural techniques

monoculture, row cropping, overgrazing, improper plowing of the soil, and removing crop wastes instead of plowing the organic material back to the soil

Sheet erosion

soil moves off in horizontal layer

rill erosion

fast-moving water cuts small channels in the soil

gully erosion

extreme case of rill erosion, where over time, channels increase in size and depth

Soil erosion damages...

agriculture, waterways (canals), and infrastructures (dams), wetland ecosystems, reproductive cycles (salmon), oxygen capacity, and pH of water


productive potential of arid or semiarid land falls by at least 10% due to human activity and/or climate change


Water that is not absorbed into the soil and evaporates leaves behind dissolved salts in topsoil


saturation of soil with water resulting in a rise in the water table


masses of rock, earth, or debris move down a slope; also known as debris flows; landslides are caused by the turbances in the natural stability of a slope, occur after droughts, earthquakes, or volcanic eruptions,


formed by cooling and classified by their silica content

Intrusive igneous rock

soildify deep underground, cool slowly, and have large-grained texture

Extrusive igneous

rocks solidify on or near the surface, cool quickly and have a fine-grained smooth texture (basalt)


formed by intense heat and pressure
High quartz content --> sandy soil
Slate --> silt soil
Marble --> limestone clay
Common examples: diamond, marble, asbestos, slate anthracite coal


formed by poling and cementing of various materials (diatoms, weathered chemical precipitates, fragments of older rocks) over time in a low-lying area, fossils only form in this

1935 Soil Erosion Act

established the soil conservation service, mandates the protection of the nation's soil reserves, deals with soil erosion problems, carries out soil surveys, and does research on soil salinity, provides computer databases for scientific research

1977 Soil and Water Conservation Act

provides for a continuing appraisal of US soil, water, and related resources, including fish and wildlife habitats and soil and water conservation program to assist landowners and land users in furthering soil and water conservation

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