AP®︎ Environmental Science: Topic 4.2 Flashcards

The biologically active layer of weathered mineral material and organic matter covering much of Earth’s land surface

The slow development of soil as parent material is weathered, may be transported and deposited, and is altered and organized into horizons

The underlying rock or transported sediment from which a soil’s mineral material develops

The physical breakdown or chemical alteration of rock and minerals without their removal and transport

The breakdown of rock into smaller pieces without changing its chemical composition

Physical weathering in which water repeatedly freezes, expands, and widens cracks in rock

Physical weathering in which particles carried by wind, water, or ice scrape and grind rock

Physical weathering in which reduced pressure causes exposed rock’s outer layers to separate or peel away

Physical weathering in which growing plant roots force open cracks in rock

The alteration of rock’s mineral composition through chemical reactions, especially reactions involving water

Chemical weathering in which water or weak acids dissolve susceptible minerals

Chemical weathering in which oxygen reacts with minerals, especially iron-bearing minerals, to form oxides

Physical or chemical weathering caused by organisms, such as roots, burrowing animals, lichens, fungi, and microbes

Dark, relatively stable, partly decomposed and chemically altered organic matter in soil

Sediment transported and deposited by flowing water, especially along rivers and floodplains

Fine wind-deposited sediment composed mainly of silt-sized particles

Soil and rock material moved downslope primarily by gravity

Parent material, climate, organisms, topography or relief, and time

Soil-forming processes that introduce material, such as litter, dust, sediment, or dissolved substances

Soil-forming processes that remove material through erosion, leaching, harvest, or gas release

Soil-forming processes that alter materials, such as mineral weathering or decomposition into humus

Soil-forming processes that move material from one horizon to another, usually by water or organisms

A vertical section showing soil horizons from the surface to parent material or bedrock, ideally O-A-E-B-C-R.

A soil layer distinguished from adjacent layers by composition, organic content, color, structure, or weathering

The downward removal and transport of dissolved or suspended materials by water moving through soil

The surface organic horizon containing litter, dead organisms, decomposing material, and humus

The upper mineral horizon mixed with organic matter and rich in roots and biological activity

A pale, depleted horizon from which clay, iron, aluminum, and organic compounds have been removed by eluviation

The removal of fine particles and dissolved materials from an upper soil horizon by downward-moving water

A mineral horizon where clay and iron- or aluminum-bearing compounds transported from above often accumulate

The deposition and accumulation in a lower horizon of materials transported from horizons above

Partly weathered parent material with little organic matter or biological alteration

Consolidated, relatively unweathered bedrock beneath the soil and parent material

The detachment, transport, and eventual deposition of soil particles by agents such as water or wind

The detachment of soil by raindrops and its transport downslope by surface runoff

The dislodging of soil particles by the impact of falling raindrops

The relatively even removal of a thin layer of soil by broad surface runoff

Water erosion in which runoff cuts many small channels into the soil surface

Water erosion in which concentrated runoff forms channels too deep to remove by ordinary cultivation

The detachment and transport of dry, loose soil by wind

A 1930s Great Plains disaster in which cultivation, loss of native grasses, drought, and wind caused severe dust storms and soil loss

Crops planted to keep soil covered so roots anchor it and foliage protects it from rain and wind

Limiting soil disturbance and leaving crop residue on the surface to maintain cover and reduce erosion

Plowing across a slope’s contours rather than downhill so furrows slow runoff and erosion

Converting a long, steep slope into shorter, flatter steps to slow runoff and reduce erosion

Rows of trees or shrubs planted to reduce wind speed and protect exposed soil

Vegetated areas beside streams that stabilize banks, slow runoff, and trap sediment before it reaches the water