Earth Science: Chapter 8 – Weathering and Soil Formation

the chemical and physical processes that break down rock at Earth’s surface

the process by which water, ice, wind, or gravity moves weathered rock or soil

the geologic principle that the same geologic processes that operate today operated in the past to change Earth’s surface

mechanical weathering
the type of weathering in which rock is physically broken down into smaller pieces

the grinding away of rock by other rock

ice wedging
process that splits rock when water seeps into cracks, then freezes and expands

chemical weathering
the process that breaks down rock through chemical changes

a chemical change in which a substance combines with oxygen, as when iron oxidizes, forming rust

characteristic of a material that is full of tiny, connected air spaces that water can seep through

the loose, weathered material on Earth’s surface in which plants can grow

the solid layer of rock beneath the soil

dark-colored organic material in soil

a measure of how well soil supports plant grown

rich, fertile soil that is made up of about equal parts of clay, sand, and silt

soil horizon
the layer of soil that differs in color and texture from the layers above or below it

mixture of humus, clay, and other minerals that forms the crumbly, topmost layer of soil

the layer of soil beneath the topsoil that contains mostly clay and other minerals

the loose layer of dead plant leaves and stems on the surface of the soil

soil organism that breaks down the remains of organisms and digests them

a thick mass of grass roots and soil

natural resource
anything in the environment that humans use

Dust Bowl
the area of the Great Plains where wind erosion caused soil loss during the 1930’s

soil conservation
the management of soil to prevent its destruction

contour plowing
plowing fields along the curves of a slope to prevent soil loss

conservation plowing
soil conservation method in which the dead stalks from the previous year’s crop are left in the ground to hold the soil in place

crop rotation
the planting of different crops in a field each year to maintain the soil’s fertility

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