Unit 5: Soil Formation and Layers Flashcards
Weathering
Occurs when rock is exposed to air, water, certain chemical compounds, or biological agents.
Three types of weathering
Physical, chemical, and biological
Erosion
The physical removal of rock fragments from a landscape.
Soil horizon
A horizontal layer in a soil defined by physical features.
How does soil form?
Parent rock is weathered and erosion causes debris and organic matter to accumulate and eventually become mature soil.
5 factors that determine the properties of soil
Parent material, climate, topography, organisms, and time.
Ecosystem services soil provides
Provides plants with nutrients, stores water, filters water.
Order of soil horizons
O, A, E, B, C
O horizon
Organic matter in various stages of decomposition.
A horizon
Top soil, zone of overlying organic material mixed with underlying mineral material.
E horizon
Zone of leaching of metals and nutrients; occurs in some soils beneath either the O or the A.
B horizon
Subsoil, zone of accumulation of metals and nutrients.
C horizon
Subsoil, least-weathered portion of the soil profile, similar to the parent material.
Physical weathering
Wind, rain, thawing ice
Chemical weathering
Acids, bases
