Weathering Flashcards
What are sub aerial processes?
Processes that occur above the water line
What is mechanical weathering?
When docks break up with no chemical changes
What is biological weathering?
Rocks breakdown due to organic activity
What is chemical weathering?
Rocks breakdown due to a chemical reaction
Explain freeze thaw:
Water finds its way into small cracks in the rock, when nighttime temperatures reach below freezing (0 degrees Celsius), the water in the crack freezes forming ice, the water expands as it freezes creating huge forces on the surrounding areas of the rock, these acting forces makes the cracks in the rock get bigger, when the temperature rises again the frozen water thaws, this cycle occurs many times until eventually a fragment of the rock breaks away completely
Explain wetting and drying:
In warmer climates where water doesn’t freeze, works the same as freeze thaw without freezing, often occurs in the Inter-tidal zone (the area is exposed at low tide but covered at high tide, rocks expand when they are wet and contact again when dry
Explain salt crystallisation:
Occurs because salt crystals are larger than water molecules, this creates pressure on the rocking causing it to breakdown, water collects in the cracks when it rains, when the sun shines the water evaporates, salt crystals are left behind in cracks and grow over time and create stress on the rock causing it to break up
Explain exfoliation weathering:
Occurs in hot climates, when rocks warm up during the day the rock expands exerting outward pressure, at night when the rocks cool and contract, overtime, causes very thin pieces of rock to flake off over time
Explain biological weathering:
Nesting birds and small burrowing animals like rabbits can cause rock to breakdown, as plants grows the roots enter the cracks in the rock under the soil as the plant and roots grow the roots causes the crack ro get larger until the rock breaks away
Explain carbonation: Chemical Weathering
When rain is slightly acidic (caused by the release of sulfur dioxide and nitrogen oxides into the atmosphere, where they react with water, oxygen and other chemicals to become sulfúrico and nitric acids respectively, the pH of acid impacted rain is generally below 4.5 on the pH scale) and reacts with carbonate rocks like limestone causing them to dissolve
Explain Oxidation: Chemical Weathering
When iron minerals in the rock react with oxygen in the air causing rusting and breakdown of rock
Explain Solution: Chemical Weathering
When other salt minerals in the rock are dissolved
