12 terms

3rd Grade Science - Soil

Soil, Weathering, Erosion
STUDY
PLAY
Soil
Outermost layer of or planet made of rock, sand, clay, silt, and humus.
Gravel
Small pieces of rock mixed with soil
Clay
Contains tiny particles of soil that holds water well and provides nutrients
Sand
Made up of small grains of worn-down rock, has few nutrients, and does not hold water well
Humus
Made up of the decayed remains of anything that was once alive; adds nutrients to the soil
Silt
Made up of very small broken pieces of rock; it's particles are larger than clay and smaller than sand
Weathering
A process that causes changes to the surface features of the Earth as wind, water, plants, and animals break down rocks; is important to the growth of healthy plants
Erosion
Movement of rocks and soil by wind, water, or ice, people and animals; some rock and soil is buried, while other rock and soil is uncovered
Topsoil, Subsoil, Bedrock
Three main layers of soil
Topsoil
Top layer of soil we see everyday; gives support and nutrients needed by the plants to grow; area where the plant roots are found
Subsoil
Middle layer of soil that contains minerals which are washed down from the topsoil layer; is a mixture of rock and soil; only large tree roots can be found in this layer
Bedrock
Bottom layer of soil made up of many layers of rock; is the thickest layer