Topic 3: Erosion

"Big Rock" at Okatoks is a glacial erratic(boulder) left following retreat of
the last ice age 10,000 years ago.

• students will understand the process of erosion and weathering
• students will appreciate the effects of erosion on the landscape in which they live.

New words:

Erosion: is the movement of rock and mineral grains from one place to another.

Sediments: are the grains that come from larger rocks that have broken down or have been worn away.

Weathering: the mechanical, chemical or biological breakdown of rocks.

Mechanical weathering: is the physical breakdown or disintegration of rocks e.g

• gravity: rocks roll down a slope and break apart
• rocks in a fast moving stream bump against each other and become smooth and round.
• temperature change - during the spring snow melts during the day and freezes at night (freeze-thaw). The melt water seeps into rock cracks and expand when the temperature falls below zero. Each freeze-thaw action causes the crack to widen until eventually a piece of rock breaks apart.

Frost wedging: the freeze thaw process during mechanical weathering.

Sedimentation: the build up of weathered material.

Chemical weathering: the break down of minerals through chemical reaction such as acid rain (sulphur dioxide and other pollutants that are dissolved in the rain).

Biological weathering: is the physical or chemical break down of minerals caused by living organisms such as plants or animals. Physical weathering occurs when plant roots expand in cracks in the rock. Acidic fluids (pee) from animals can cause chemical reactions.

Abrasion: wearing down of rocks by wind, fast moving water or ice action.

Moraines: piles of sediments that have been push aside or deposited by the melt waters from ice sheets or glaciers.

Drumlins: egg-shaped mounds left under the ice sheet by the meltwater as the glacier retreats. Look out for drumlins on the right side of the road at Morley on your next drive to Banff or Kananaskas.

Resources: Text Book pages 352-441

• Weathering and erosion (including animations)
• Glacial landforms
• Drumlins
• Our Canadian Dynamic Earth
• Water Erosion control
• Wind Erosion prevention

Morley Bow Valley, Alberta (along Highway 1 between Calgary and Banff)

Glaciers and Moraines

Postcard from the Earth's Crust in Canada

Research one of the following land forms, or one that you choose for yourself.

• Carlsbad Caves (water erosion) Cave formation
• Okatoks rock (glacial erosion) Formation (scroll down to "glacial deposition")
• Columbia Icefields (glacier) How glaciers are formed
• Glacial striations
• Frank Slide - landslide
• Drumlins - drumlin field on Highway 1 to Banff
• Maligne Canyon (water erosion)
• Glacial moraine
• Waterfalls

You will need to research the landform from one of the above sites, but you will also need to research HOW that landform was formed. Use a search engine e.g.

• google.ca
• altavistacanada.com

Develop a post card on the paper provided the you could send to a friend

On the postcard:

• Describe where the landform is - country etc (2pts)
• Describe features - what it looks like, size, shape, materials (5 pts)
• Describe how it is FORMED (type of weathering) (5pts)
• All information and picture must go on one side. You may construct this on computer software if you wish.
• Mount or print card (5 pts)

Mount the picture and information on the paper provided or produce a computer generated postcard.

Be sure that someone else has proof read your card before you hand it in.

Resource: Name of source(s).

Evaluation:

top