Define and give examples of physical weathering and chemical weathering.

Chemical Weathering-the erosion or disintegration of rocks, building materials, etc., caused by chemical reactions (chiefly with water and substances dissolved in it) rather than by mechanical processes. Examples:

1) Oxidation - reaction with oxygen to form an oxide (Iron Oxide)

2) Dissolution - the ions of a substance separate in a liquid, thus dissolving the substance (dissolving the ions of carbonic acid with water, making water acidic)

3) Hydrolysis - hydrogen ions replace positive ions in minerals (chemical alteration of K Feldspar Orthoclase)

Physical Weathering - are processes that turn big particles of rock into smaller particles over time.

Examples:

1. Rivers

Rivers and moving bodies of water like waves in a lake are responsible for a lot of the physical weathering that takes place. As rocks are lifted by the moving water, they either crash back down to the river bed or sea floor and slowly break, or they collide with other rocks or objects like fallen logs, causing damage to the surface. Over time, these rocks will lose their surfaces and become more rounded and smooth.

2. Ice

Water can also affect the physical weathering of rocks through much faster means, such as when water gets into the cracks and crevices of rock and freezes, causing the rock to break and occasionally even shatter in something much like an explosion. This phenomenon also happens in streets and roads, causing much the same result as ice wedges form and break up the road's rock composite. Glaciers are also responsible for a good deal of physical weathering as the move along the rocky surface, and as they freeze and melt and refreeze on top of rocky soil.

3. Plant Growth

Plants are responsible for the physical weathering of rocks as their roots grow up through the surface of the ground and rock face. These roots eventually push up on the rock with enough force that the rock weakens, causing cracks and crevices to form that can eventually led to breakage.