Term 
         | 
        
        
        Definition 
        
        | a principle that states that the geological processes that operate today also operated in the past |  
          | 
        
        
         | 
        
        
        Term 
         | 
        
        
        Definition 
        
        | the process of wearing down and carrying away rocks |  
          | 
        
        
         | 
        
        
        Term 
         | 
        
        
        Definition 
        
        | the process that breaks down rock and other substances |  
          | 
        
        
         | 
        
        
        Term 
         | 
        
        
        Definition 
        
        | a type of weathering in which rock is physically broken down into smaller pieces. |  
          | 
        
        
         | 
        
        
        Term 
         | 
        
        
        Definition 
        
        | the process that breaks down rock through chemical changes |  
          | 
        
        
         | 
        
        
        Term 
         | 
        
        
        Definition 
        
        | refers to the weathering away of rock by rock particles carried by water, ice, wind, or gravity |  
          | 
        
        
         | 
        
        
        Term 
         | 
        
        
        Definition 
        
        | the process of rock being forced apart by water seeping into cracks in rock, freezing, and expanding the rock |  
          | 
        
        
         | 
        
        
        Term 
         | 
        
        
        Definition 
        
        | iron combining with oxygen in the presence of water |  
          | 
        
        
         | 
        
        
        Term 
         | 
        
        
        Definition 
        
        | when a material is full of tiny, connected air spaces that allow water to seep through it |  
          | 
        
        
         | 
        
        
        Term 
         | 
        
        
        Definition 
        
        | loose, weathered material on Earth's surface in which plants can grow |  
          | 
        
        
         | 
        
        
        Term 
         | 
        
        
        Definition 
        
        | the solid layer of rock beneath the soil |  
          | 
        
        
         | 
        
        
        Term 
         | 
        
        
        Definition 
        
        | a dark-colored substance that forms as plants and animal remains decay |  
          | 
        
        
         | 
        
        
        Term 
         | 
        
        
        Definition 
        
        | a measure of how well soil supports plant growth |  
          | 
        
        
         | 
        
        
        Term 
         | 
        
        
        Definition 
        
        | soil that is made up of about equal parts of clay, sand, and silt |  
          | 
        
        
         | 
        
        
        Term 
         | 
        
        
        Definition 
        
        | measures the acidity of a substance |  
          | 
        
        
         | 
        
        
        Term 
         | 
        
        
        Definition 
        
        | a layer of soil that differs in color, texture, and composition from the layers above or below it. |  
          | 
        
        
         | 
        
        
        Term 
         | 
        
        
        Definition 
        
        | a crumbly, dark brown soil that is a mixture of humus, clay, and other materials |  
          | 
        
        
         | 
        
        
        Term 
         | 
        
        
        Definition 
        
        | usually consists of clay and other particles of rock, but little humus |  
          | 
        
        
         | 
        
        
        Term 
         | 
        
        
        Definition 
        
        | organisms that break the remains of dead organisms into smaller pieces and digest them with chemicals |  
          | 
        
        
         | 
        
        
        Term 
         | 
        
        
        Definition 
        
        | anything in the environment that humans use |  
          | 
        
        
         | 
        
        
        Term 
         | 
        
        
        Definition 
        
        | the management of soil to limit its destruction |  
          | 
        
        
         | 
        
        
        Term 
         | 
        
        
        Definition 
        
        | a farmer plants different crops in a field each year |  
          | 
        
        
         | 
        
        
        Term 
         | 
        
        
        Definition 
        
        | farmers plow their fields along the curves of a slope instead of in straight rows |  
          | 
        
        
         | 
        
        
        Term 
         | 
        
        
        Definition 
        
        | dead weeds and stalks of the previous year's crop are plowed into the ground to help return soil nutrients, retain moisture, and hold soil in place. |  
          | 
        
        
         |