ROCKS

Weathering of Rocks

Weakening and breaking down of rocks and minerals
Due to nonliving and living factors: (a) temperature change, (b) animals, (c) plants, (d) acid, (e) salts, and (f) water.
Rocks on earth surface: weather faster than underground rocks.
Leads to soil production.

Types of Weathering affecting Rocks

Physical Weathering

Breaks rocks into smaller pieces and bits.
Freezing and Thawing of water; wherein water enters the small pores and cracks of the rocks which would expand when frozen.
Ice Wedging / Cryo-Fracturing, the occurrence where the water inside the rocks freezes and wedges rocks apart over time.
Water lifts rocks from underwater surfaces they can hit other rocks and break. Water can also transfer rocks from one place to another.

Salt can cause honeycomb weathering wherein groundwater seeps into rock cracks by capillary action and eventually evaporates.

Yields salt crystals that increase pressure in rocks and causes it to break down.
Leaves salt crystals that resemble honeycombs.
Often found in dry climates

Temperature extremes that affect rocks are called thermal stress

Common in desert climates, due to the abrupt changes of temperature during the day and night.
Causes the rocks to crumble and flake; called exfoliation.

Abrasion

Constant exposure to friction from different factors like the wind, water, or ice
Exposes rocks and breaks them down.

Chemical Weathering

Interaction of water and temperature in an environment with minerals and rocks.
Change in the molecular level of rocks and minerals.
When carbonation is created by the combination of carbon dioxide and water it yields carbonic acid that dissolves limestone and eventually produces underground limestone caves.
More common and occurs faster in tropical regions (heat and abundant water from rain).

Oxidation

Rocks with iron content react with water and oxygen, causing it to rust and wear down the rocks.

Hydration and Dehydration

Hydration is when the chemical bonds of a rock changes due to absorption of water. (e.g. water changes anhydrite to gypsum)
It leads to rock deformation.
Dehydration on the other hand is formed when water is removed from the rock (limonite to hematite)

Hydrolysis

When minerals change when exposed to acidic water (the formation of saltwater solution).

Biological Weathering

Results from living things and microbial influences.
Tree seeds when they grow into mature trees would break apart the surrounding rounds.
Plant roots would also continually spread and crack rocks.
Digging animals could break down rocks.
When animals travel over land they could break the rocks.
Living, decaying plants, and fungi produces carbonic acid that affects rocks.
Fungi also breaks down rocks to release minerals and algae, it produces holes in the rocks.
Bacteria can also change the mineral content of rocks.

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