weathering, erosion and distinctive landscapes 1.explain the terms weathering and erosion. 2.name...
TRANSCRIPT
Weathering, Erosion and Distinctive Landscapes
1. Explain the terms weathering and erosion.
2. Name and describe the process of chemical and mechanical weathering
3. Describe and draw a limestone pavement
4. Describe surface and underground landforms of a karst landscape
5. Understand how this topic appears on the exam papers.
Denudation
This is all processes involved in the shaping of the earths crust
Denudation = weathering and erosion
Weathering• Weathering is the breaking down and
decay of rocks that are exposed to the weather
• There are three types1. Mechanical – Frost and temperature
changes2. Chemical – Rocks are dissolved3. Biological – Plants and animals
Erosion
• Erosion is the breaking down and removal of the rock.
• Three types of erosion• Moving water (rivers and sea)• Moving ice (Glaciation)• Moving air (wind)
Mechanical Weathering
• 3 Types
• Freeze Thaw Action
• Exfoliation
• Crystallisation of salts – When salts in a rock grow they can split the rock apart.
In order for freeze thaw action to occur you need to have…
• Temperatures that rise above and fall below freezing (0°C)
• A good supply of water from rain, snow, sleet or hail.
Freeze Thaw Action
• http://www.absorblearning.com/media/attachment.action?quick=131&att=2799
• Where do you think this action usually occurs???
Mechanical Weathering - Exfoliation
• ‘Onion Peeling’
• Major contrasts in temperature
• Rises very high during the day and drop very low at night
• The change in temperature expands and contracts the rock causing the outer skin to shatter.
Biological Weathering
• Action of plants, animals and man can speed up mechanical and chemical weathering
Chemical Weathering
• Four types of chemical weathering1. Carbonation2. Oxidation3. Hydration4. Hydrolysis
Research the types of chemical weathering..Teach the class.
Karst Keywords
• Burren• Tower Karst Landscape• Carbonation• Calcium Carbonate• Calcite• Limestone Pavement• Swallow Hole• Cavern• Dripstone Formations
Karst Region
• These are bare limestone regions
• Ireland’s best known Karst region the Burren in Co. Clare
• Burren = Rocky place (An Boireann)
• Soil in the area removed by Erosion
• International Example – Tower Karst Landscapes
Surface and Underground Landforms
• Surface
Limestone Pavements
Swallow holes
• Underground
Caverns
Dripstone formations
Limestone Pavement
Examples
• Near Black Head in the Burren Co. Clare
• Marble Arch Uplands in Co. Fermanagh
Revision… Limestone
• In your groups do a limestone revision mindmap…
• Remember the characteristics of limestone!!
Limestone Pavement Formation
• Limestone pavements from from the process of carbonation ‘All the Cs!’
1. Carbon dioxide in the air + rain = Weak Carbonic Acid.
2. Lands on limestone rock creating a chemical reaction.
3. Hydrogen in the carbonic acid separates the calcium carbonate (limestone) into calcium and bicarbonate atoms
4. These are soluble and are washed away… as a result the limestone is dissolved.
Limestone Pavement
• An exposed area of limestone
• Limestone is permeable. When rainwater falls onto the surface of the limestone it moves underground through joints and cracks in the rock.
• It has grikes and clints
• A Limestone Pavement is just like a bar of dairymilk chocolate!!
• Each group will be given a bar of chocolate…. I’d like you to describe the physical features of the bar of chocolate…
• DO NOT EAT IT!! WE NEED IT FOR THE REST OF THE CLASS!!
Clints
• These are the top flat pieces of the limestone.
• These are formed by chemical weathering dissolving away some of the rock landscape.
Grikes
• These are the joints or cracks between the Clints
• These have been formed by chemical weathering.
• Carbonic acid (acid rain) expands the width and depth of the cracks
Class Activity• Read page 59 of your book.
Exam QuestionDescribe the formation of any one rock typeand how it produces a distinctive landscape.
- Describe the formation of limestone… notes from rock chaper
- Describe formation of a karst landscape and limestone pavements
- Use two examples Burren Co. Clare and Tower Karst Landscape (page 63)
Sinkholes/Swallow holes
An opening in the bed of the river through
which a river disappears underground in a
limestone region
Class Activity: Sinkholes
• Read the formation of a sinkhole on page 60 of your book.
• Summarise the landforms in grouop
Animation of a Cavern
• http://www.classzone.com/books/earth_science/terc/content/visualizations/es1405/es1405page01.cfm
Dripstone formations
• Include stalactites, stalagmites, pillars, columns and curtains.
• Formed from the mineral calcite. Calcium carbonate in its purest form.
• Read page 62 in your book. Summarise into your own words.
Stalagmites
• When the drops of water fall to the floor and evaporate, they also deposit calcite. These deposits build up in a conical shape to form Stalagmites
Stalactites
• When water containing dissolved calcium carbonate seeps through the rock, some drops hang from the roof of the cave/cavern for a while. Some of the water evaporates leaving behind deposits of calcite. These deposits build up over thousands of years and hang from the roof
to form Stalactites.
• Prepare questions to suit both surface and underground.
Exam Questions: Could be asked for Underground or Surface Landforms
Weathering, Erosion and Distinctive Landscapes
1. Explain the terms weathering and erosion.
2. Name and describe the process of chemical and mechanical weathering
3. Describe and draw a limestone pavement
4. Describe surface and underground landforms of a karst landscape
5. Understand how this topic appears on the exam papers.