Structure of the Earth-SSMS

Term Definition
rock cycle the cycle in which rocks form
rocks consolidated or unconsolidated solid mineral matter
mineral a naturally occurring, inorganic solid that has a crystal structure and a definite chemical composition
crust the layer of rock that forms Earth's outer surface
mantle the layer of hot, solid material between Earth's crust and core
bedrock the solid layer of rock beneath the soil
humus dark-colored organic material in soil
fertility a measure of how well soil supports plant growth
loam 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
topsoil an upper layer of soil consisting of rock fragments, nutrients, water, air, and decaying plant and animal matter
subsoil the layer of soil beneath the topsoil that contains mostly clay and other minerals
litter the loose layer of dead plant leaves and stems on the surface of the soil
decomposition to cause something (such as dead plants and the bodies of dead animals) to be slowly destroyed and broken down by natural processes, chemicals, etc.
contour plowing plowing fields along the curves of a slope to prevent soil loss
crop rotation the planting of different crops in a field each year to maintain soil's fertility
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 into place
sod a thick mass of grass roots and soil
natural resource anything in the environment that humans use
soil conservation the management of soil to prevent its destruction
earthquakes the shaking that results from the movement of rock beneath Earth's surface
tectonic plate theory how scientist thought plate tectonics came about