Soils and Weathering

Terms:
physical and chemical weathering, exfoliation, acids and bases, zone of leaching, zone of accumulation, soil texture, gravitational water, capillary water, hygroscopic water, field capacity, micelle, cations and anions, loam, podzolization, laterization, salinization

acids: a substance that increases the hydrogen ion concentration in a solution, pH < 7.

anions: Negatively charged ions.

bases: a substance the decreases the hydrogen ion concentration in a solution, pH > 7.

cations: Postively charged ions.

capillary water: Water trapped between soil particles through adhesion and cohesion of the water molecules with each other and with the soil.

chemical weathering: The weathering process based on chemical reactions such as acidic water on rock that promotes erosion.

exfoliation: When freeze-thaw action causes rock to crack and erode, sometime in layers that peel off the rock.

field capacity:  The amount of capillary and hygroscopic water remaining in a soil after the gravitational water has drained out, as measured 1-2 days after a soaking rain. 

gravitational water: Water in a soil that percolates through to the water table.

hygroscopic water:  Water molecules that are tightly bound to clay particles (micelles) in a soil.

laterization: A soil-forming process in highly oxidized environment that results in a weathered, iron-rich and brick-like soil.

loam: Soil with an even mixture of sand, silt, and clay particles.

micelle:  A negatively charged clay particle in soil. 

physical weathering:  The weathering process based only on physical actions such as wind, rain, waves, etc.

podzolization: A soil-forming process with intense leaching, usually in acidic conditions in a coniferous forest where rainfall exceeds evaporation, that is characterized by a nutrient poor, white E horizon.

salinization:  A soil process caused by reverse leaching where evaporation exceeds rainfall causing salts and/or carbonates to leach upwards to the surface in the soil where they precipitate out. 

soil texture: The structure of a soil based on the relative proportion of particle sizes (sand, silt, and clay) present within it.

zone of accumulation: The section in a soil profile where nutrients accumulate and where water stops percolating through the soil, B horizon.

zone of leaching: The section in a soil profile where leaching of nutrients is most prevalent due to water percolation, E horizon.