How Is Weathering Different From Mass Wasting?

Mechanical Weathering

• Mechanical weathering occurs when elements alter the physical structure of earth without altering its chemical composition. This occurs most often in instances where water and earth interact. For example, when water seeps into cracks in the earth and freezes, it expands the cracks, which in turn allow more water to enter, which in turn freezes and expands the cracks further. Additionally, heavy rainstorms often result in the formation of rivulets and streams which quickly sweep loose earth along the water's current.

Chemical Weathering

• Chemical weathering refers to a chemical change in the earth itself, either because of foreign factors, or because of the chemical interactions of the earth with other materials, such as biomass. As with mechanical weathering, chemical weathering typically takes place when moisture is involved. For example, as water drips off of the ceiling of a cave, it carries with it and deposits tiny bits of rock matter -- typically limestone -- which concentrates and forms a stalactite.

"Slow" Mass Waste

• Though mass waste refers to the fastest form of earth change, so-called "slow" mass waste, primarily known as earth creep, can take several days or weeks to fully occur. Creep refers to the slow surface shifting of earth, typically on gentle hill sides. Think of creep as the earth slouching. Gravity slowly drags masses of earth down, sometimes breaking the sinking mass away from the stationary mass, creating a fissure, crack or gap in the earth.

"Fast" Mass Waste

• Most "fast" mass waste produces dangerous and violent events. Rock slides, mudslides and avalanches all count as instances of "fast" mass waste. In these events, chunks of earth break apart from their settled positions, most often on the sides of steep hills, and tumble down until coming to a complete stop at the bottom of the hill.