Science Focus Topic 3 Notes: Erosion | Print |
Erosion is the movement of rock and mineral grains from one place to another. Weathering (3 types) breaks down and wears away rock, creating sediment.

Mechanical Weathering

- the physical break-up or disintegration of rocks, caused by gravity, temperature change and frost wedging
- mechanical weathering ?wears away?
- sedimentation ?builds-up?

Chemical Weathering

- chemicals, present in the earth?s surface or atmosphere, can be dissolved in water and react in the chemical decomposition of rocks and minerals (acid rain)

Biological Weathering

- living organisms (plants, animals, bacteria and fungi ) can breakdown rock
- plant roots, acidic fluids produced by roots, bacteria, fungi and some insects and small animals can cause chemical reactions

The Changing Surface of the Earth

- agents of erosion include: glaciers, gravity, wind, and water
- changes can occur
gradually (glaciers) or suddenly ( flash floods, landslides, rock slides)
- large rocks caught up in a glacier and then left behind when the glacier recedes are called
- sediment that is push away, as the glacier moves forward, are called
- scratches, made in the bedrock, by glaciers carrying rocks are called
- gravity causes landslides and rock slides ? eg. Frank Slide (a
retaining wall can often be used to hold back unstable material ? but this is not always the best protection)
- wind carries rock particles across the landscape, eroding the land by
abrasion (planting vegetation, contour farming and reduced tillage can reduce the effects of wind erosion)

Water in Motion

- Water is one of the most powerful causes of erosion
- Sudden or incremental changes occur due to the movement of water - rivers, rain, ocean waves
- When a river becomes mature it begins to meander (curving its bed from side to side)


- Dinosaur Provincial Park (The Badlands)
- Road repair due to frost wedging
- Frank Slide Interpretive Centre
- Okotoks ?Big Rock? ? an erratic
- Moraines in Banff national Park
- Athabasca River deepens the quartzite rock, making a canyon
Caving ? ?Discover what treasures the spaces hold? (especially the Castleguard Cave, near the Columbia Icefield (It is 18km long)

WRAP-UP p. 381
A good review of the first three topics in this Unit