terracing		the removal and transport of material by wind, water or ice.
erosion		a process farmers use to change a steep field into a series of smaller flat fields
Iron		loose mixture of small mineral fragments and organic material
acid precipitation		the grinding and wearing down of rock into new substances
carbonic acid		the breakdown of rock into smaller pieces
differential weathering		very small particles of decayed plant and animal material in soil
topsoil		rust is produced by the oxidation of this mineral
leaching		soft, less weather resistant rocks wear away
chemical weathering		precipitation that contains acid due to air pollution
soil		chemical reaction which an element combines with oxygen to form an oxide
contour plowing		breakdown of rock by physical means
soil conservation		the main reason farmers use crop rotation is to slow down the process of
bedrock		when farmers plow across the slope instead of up and down a hill
oxidation		various methods by which humans take care of the soil
parent rock		layer of rock beneath the soil
abrasion		rock that is the source of soil
humus		the acid that is normally involved in the formation of caves
weathering		process by which water flows into cracks in rock and expands as it freezes
nutrient depletion		process that rainwater dissolves and carries away minerals and soil
mechanical weathering		chemical breakdown of rock into new substances
ice wedging		the top layer of soil that generally contains humus