Physical Processes & Chemical Processes

What is weathering?

Weathering is the breakdown of rocks in situ.

How does erosion differ from weathering?

Erosion involves the breakdown of material through movement processes.

Which rocks are least resistant to weathering?

Limestones and sandstones are the least resistant to weathering.

What does physical weathering produce?

Physical weathering produces small, angular fragments of the same rock.

What is freeze-thaw weathering?

Freeze-thaw occurs in cold areas where water freezes in cracks in rocks, expanding 10% and exerting pressure to break the rock.

How does freeze-thaw weathering work?

Water collects in cracks, freezes, and expands, causing the crack to widen when pressure exceeds the rock's resistance.

What is exfoliation?

Exfoliation occurs in hot deserts with large diurnal temperature ranges, causing outer layers of rock to flake off.

How does salt crystal growth weather rocks?

Salt crystal growth occurs when saline solutions penetrate rock surfaces, and as water evaporates, salt crystals form and expand.

What temperature range is salt crystal growth most effective in?

Salt crystal growth is most effective in temperatures around 27°C.

What is dilation in weathering?

Dilation is a pressure-release process where rocks expand and form fractures when overlying rocks are removed.

What happens when horizontal pressure is released in dilation?

Vertical faults develop, often seen on cliff faces.

How does vegetation root action contribute to weathering?

Vegetation root action can penetrate rocks or prevent rocks from forming or settling, contributing to weathering.

What does chemical weathering create?

Chemical weathering creates altered rock substances and requires water to occur.

What is hydrolysis in weathering?

Hydrolysis is the breakdown of rocks with feldspar minerals by acidic water.

What does hydrolysis produce?

Hydrolysis produces kaolin (clay), silicic acid, and potassium hydroxyl.

What is hydration in weathering?

Hydration occurs when minerals absorb water and expand, causing mechanical and chemical stresses.

How does hydration affect clay minerals?

Clay minerals absorb water and expand, forming hydrates like gypsum, resulting in significant expansion and cracking.

What is carbonation in weathering?

Carbonation is the process where acid rain breaks down limestone or chalk.

What happens during carbonation weathering?

Carbonic acid reacts with calcium carbonate in limestone to form calcium bicarbonate, which is soluble and washed away.