Weathering Flashcards
What are the four contributions to weathering?
water, wind, ice, gravity
What are the four mechanical breakdowns?
Frost wedging, salt wedging, exfoliation (pressure release), root wedging
Frost wedging weathering
conditions: cold weather
Freeze-thaw cycle:
-water freezes, expands, and exceeds the tensile strength of the rock, causing it to split
salt wedging weathering
Conditions: coastal areas/ arid climate (desert climate)/ polluted air
- evaporation of seawater leaves behind salt. The salt then grows and expands, exerting pressure on the surrounding rocks.
Exfoliation weathering
Conditions: significant temperature variations
- outer layers of rocks peel away
-expansion and contracting during day and night
root wedging weathering
-plant roots cause cracks in the rocks
- as the roots grow, they will make room for themselves by intruding into the rocks resulting in the surrounding rocks cracking.
What are the four chemical breakdowns?
solution (dissolution), hydrolysis, oxidation, hydration
solution (dissolution) weathering
When rocks break down into their ions when put into a solution (mostly just water or acidic water)
The solution is only a spectator ion and does not react.
hydrolysis weathering
When put in water (which can be an acidic solution), the rock undergoes a reaction that creates a new mineral.
oxidation weathering
When the minerals react with free oxygen with metallic material
- leads to rusting or discolouration of rocks
Hydration weathering
When minerals absorb surrounding water to create a new mineral
Aids in mechanical and chemical weathering
-faults and fracture points
- porosity
- surface area
- temperature
Goldich’s weathering series
- minerals formed under high temperatures are the most unstable; therefore most susceptible to chemical weathering under atmospheric conditions
tailing
really fine particles of crushed rocks
