3. Rocks and weathering Destructive
Friday, April 7, 2023 10:17 AM
Convergent
Collision
Type of plate Divergent Constructiv
boundaries
Conservative/Transform
Weathering is the weakening and breakdown
Disintegration: physical breakdown of rocks
of rocks in situ (no element of movement is
Decomposition: chemical breakdown of rocks Physical weathering
involved, the material remains there).
Types of weathering: 1. Freeze thaw (ice crystal growth/frost shattering) occurs when
1. Physical/mechanical (disintegration) - atmospheric conditions
water in joints and cracks freezes at 0 degrees Celsius. It
that produce smaller, angular fragments of the same rock, such
expands by about 10 percent and exerts pressure. These
as scree.
pressures greatly exceed most rocks' resistance. It is most
2. Chemical (decomposition) - chemical reactions and creation of
effective in environments where moisture is plentiful and there
altered rock substances, such as kaolinite (china clay) from
are frequent fluctuations above and below freezing point.
granite.
3. Biological (disintegration and decomposition) - plants and (thawing = 解冻)
Plate boundaries: a plate boundary is w
animals chemically alter rocks and physically break rocks
through their growth and movement. Plates can move:
- Towards each other = converge
- Away from each other = diverge
2. Salt crystallisation (salt crystal growth) causes the decomposition of - Slide past each other = conserv
Friday, April 7, 2023 10:17 AM
Convergent
Collision
Type of plate Divergent Constructiv
boundaries
Conservative/Transform
Weathering is the weakening and breakdown
Disintegration: physical breakdown of rocks
of rocks in situ (no element of movement is
Decomposition: chemical breakdown of rocks Physical weathering
involved, the material remains there).
Types of weathering: 1. Freeze thaw (ice crystal growth/frost shattering) occurs when
1. Physical/mechanical (disintegration) - atmospheric conditions
water in joints and cracks freezes at 0 degrees Celsius. It
that produce smaller, angular fragments of the same rock, such
expands by about 10 percent and exerts pressure. These
as scree.
pressures greatly exceed most rocks' resistance. It is most
2. Chemical (decomposition) - chemical reactions and creation of
effective in environments where moisture is plentiful and there
altered rock substances, such as kaolinite (china clay) from
are frequent fluctuations above and below freezing point.
granite.
3. Biological (disintegration and decomposition) - plants and (thawing = 解冻)
Plate boundaries: a plate boundary is w
animals chemically alter rocks and physically break rocks
through their growth and movement. Plates can move:
- Towards each other = converge
- Away from each other = diverge
2. Salt crystallisation (salt crystal growth) causes the decomposition of - Slide past each other = conserv
