Landscapes: Glaciation unit.

Unit aims: To find out what we mean by glaciation. To find out how landscapes have been changed by glaciation. To be able to identify different glacial land features. To see how humans use glaciated landscapes.

What is Glaciation? THE ICE AGE.

Glaciation To understand glaciation we must understand that the planet earth has gone through a number of ice ages.

Climate Change is not new! From “Glaciers” by John Gordon Colin Baxter Publications, 2001

Interglacial periods Glacial periods From “Glaciers” by John Gordon Colin Baxter Publications, 2001

THE ICE AGE THE LAST ICE AGE BEGAN ABOUT 2 MILLION YEARS AGO!! AND LASTED UNTIL ABOUT 10,000 YEARS AGO. DURING THE ICE AGE THE CLIMATE BEGAN TO GET COLDER AND ICE SPREAD OUT FROM THE NORTH AND SOUTH POLE. HEAVY SNOW FELL ON THE MOUNTAINS OF BRITAIN AND EUROPE. THIS LEAD TO THE FORMATION OF GLACIERS THESE GLACIERS SHAPED THE LAND AROUND THEM AND WHEN THEY MELTED WE WERE LEFT WITH GLACIAL LAND FORMS.

Areas of Glaciation in the UK A – The North West Highlands B – The Grampian Mountains C – The Cumbrian Mountains D – The Cambrian Mountains A B C D

What is a Glacier? A GLACIER IS FORMED WHEN SNOW FALLS ON AN AREA FOR A LONG PERIOD OF TIME WITHOUT MELTING AWAY. OVER TIME THIS SNOW COMPACTS AND IS TURNED INTO GLACIAL ICE. DUE TO ITS EXTREME WEIGHT AND THE FORCES OF GRAVITY THE GLACIER WILL BEGIN TO MOVE SLOWLY DOWNHILL. It is sometimes referred to as a river of ice.

How glaciers change the landscape Erosion Transportation Deposition When the ice wears away the land. When the ice moves material. When the ice drops material.

Important terms: Freeze Thaw: This is when water gets into cracks in the rock and then freezes. Because it expands it then breaks the rock away.

Important terms: Plucking: The ice freezes around chunks of rock at the bottom and sides of the glacier. As the ice then moves it tears the rock away with it.

Important terms: Abrasion: All of the material under the glacier is known as moraine. This mix of rocks and other material act like sandpaper wearing away the valley floor beneath and at the sides of the glacier.

Task. Draw a cartoon picture that will remind you of: Plucking Abrasion Freeze thaw. (Hint: Think of what they do, is there anything in your life that is similar?)

Re-Cap What have we leant in Glaciation so far? 2 minutes to discuss with the person next to you and come up with the 5 key things that we have learnt about Glaciation so far.

Glaciation There has been a number of ice-ages throughout the history of the Earth. These ice ages have changed the shaped of landscapes. Three important terms: (1) Freeze-thaw (2) Plucking (3) Abrasion

Glaciers are extremely powerful! They move through valleys like a bulldozer eroding everything in their way. What would happen if a bulldozer came through the class? EVERYTHING would just be pushed out of the way. Because of this we say that the material moved by a glacier is unsorted.

Glacial Erosion As the glacier is so powerful it creates many features of Glacial erosion. When answering a question like this it is very similar to answering a river question you need: A description Diagrams Labels.

Corrie

U-shaped valley

Arete

Pyramidal peak

hanging valley and truncated spurs

Formation of a Corrie Snow collects in a natural hollow on the side of a mountain. Over time, the weight of the snow compacts and it turns into ice. The hollow is deepened and widened by the corrie glacier through the processes of abrasion and plucking.

Formation of a Corrie Plucking occurs on the back wall making it steep and abrasion occurs on the bottom of the Corrie making it deeper. This over-deepening leads to an ‘armchair’ shape characteristic of a corrie and causes a ‘rock lip’ to be formed. Freeze thaw occurs and makes the peak jagged.

Formation of a Corrie The ice eventually moves out over the rock lip and flows down the valley as a glacier. When the glacier melts a Corrie is left. It has an “armchair” shape, with steep back walls and a deep bottom. A Corrie Lochan or Tarn is often left in the corrie too.

Diagrams

Diagrams for the corrie. CREVASSE

Corrie Task: What labels could you add to this. If it was a field sketch?

Arete

Formation of an Arete. An Arete is formed when two corries meet at the back of one another. Snow collects in two natural north facing hollows on the side of a mountain. Over time, the weight of the snow compacts and it turns into ice.

Formation of an Arete. The two hollows are deepened and widened by the corrie glacier through the processes of abrasion and plucking. Plucking and freeze thaw cause the back walls to become steep. Abrasion makes the hollows deeper. The two back walls meet and a “knife edge” ridge is formed.

Pyramidal peak

Formation of a pyramidal peak. How do you think this could be formed? Think about what we have leant so far.

Pyramidal peak

Formation of a pyramidal peak. A pyramidal peak is formed when 3 or more corries meet back to back. Snow falls on natural hollows in the mountainside and over time compacts forming ice. The processes of plucking and abrasion take place making the hollows deeper (abrasion) and with steep back walls (plucking).

Formation of a pyramidal peak. As the corries erode backwards the steep back walls meet at one point creating a peak. Freeze-thaw (frost shattering) occurs on the peak creating the jagged point. When the ice melts a pyramidal peak is left with at least 3 corries around it.

THE FORMATION OF A U-SHAPED VALLEY Before glaciation there would have been a v- shaped valley that was caused by a river. Over time snow would have gathered and compacted to form a glacier high in the mountains.

Due to the force of gravity and the weight of the glacier the glacier would have began to move downhill. The glacier would have acted like a bulldozer eroding everything in it’s path. The valley would have been deepened and widened through plucking and abrasion.

After the glacier melted the valley had changed. The valley walls have been deepened and the valley floor is flat giving it its name, a U-shaped valley. There is often a thin ‘misfit stream’, given it’s name because it could not have created the valley itself.

hanging valley

Main U shaped valley Future hanging valleys

Formation of a hanging valley A hanging valley is formed when a large glacier is joined by a small tributary glacier (1) The large glacier mover down a v-shaped valley and through the processes of plucking and abrasion deepens the valley floor and straightens the valley sides, leaving a large U-shaped valley (1). The same processes of plucking and abrasion take place in the tributary glacier, but at a much slower rate (1).

This is because the large glacier is far heavier and more powerful, and therefore can erode the land more quickly (1). This different rate of erosion means that the small tributary glacier does not erode anywhere close to the depth of the large glacier. When the ice melts a large U-shaped valley is left where the large glacier had been. The smaller glacier leaves a small valley leading into this and “hanging” from the truncated spurs. (1) There is often a waterfall left coming from the hanging valley (1).

New class.

Glaciation Recap On the piece of paper you have name each of the following features of Glacial erosion.

CLIP 1140

Carousel: Glaciation On your paper you will have a number. 1: Corrie 2: U-Shaped valley 3: Arete 4: Pyramidal peak 5) hanging valley You will have 1 minute to answer the question the best you can, then you will pass it on.

Glacial Deposition. Glacial deposition is material that is transported by the glacial then dropped (deposited) when the glacier begins to melt. What do we mean by glacial deposition?

Glacial Deposition. There are 2 kinds of Glacial deposition. Glacial deposition And Fluvio-glacial deposition.

Glacial Deposition. Glacial Deposition = Transported by the ice. Unsorted Large, angular rocks. Known as Moraine or Boulder clay.

Glacial Deposition. Fluvio-glacial deposition = Transported by water (melt water) Sorted material (smaller bits go further) Sands and Gravel

Glacial Deposition.

Lateral Moraine Medial Moraine Ground Moraine Terminal Moraine

Lateral moraine is found on the sides of the glacier. Scree, from frost shattering, is an important source. Medial moraine is found down the middle of the glacial surface and occurs when the inner lateral moraines of two glaciers join. Ground moraine is found at the base (bottom) of the ice. It is also called till or boulder clay. Terminal moraine is found in front of the snout of the glacier if it is stationary. It represents the maximum advance of the ice.

lateral and medial moraine ground moraine snout terminal moraine outwash sand and gravel glacial deposition fluvioglacial deposition

Lesson starter: With the person next to you (or closest to you) give yourself a number 1 or 2. You will have 1 minute to answer the questions that come up in the boxes. What is moraine? What different types of moraine do you get? How is a U shaped valley formed? How is an Arete formed? How is a corrie formed?

Terminal Moraine

Lateral Moraine Medial Moraine Ground Moraine Terminal Moraine

Lateral moraine is found on the sides of the glacier. Scree, from frost shattering, is an important source. Medial moraine is found down the middle of the glacial surface and occurs when the inner lateral moraines of two glaciers join. Ground moraine is found at the base (bottom) of the ice. It is also called till or boulder clay. Terminal moraine is found in front of the snout of the glacier if it is stationary. It represents the maximum advance of the ice.

Formation of terminal moraine. Material such as gravel and rock is pushed along by the glacier. The glacier pushes everything in its way and therefore the material is unsorted. The material gathers at the front of the glacier. When the glacier begins to melt the moraine is left at the furthest point that it travelled. How do you think terminal moraine is formed?

Terminal moraine diagrams: Using the white boards draw three diagrams that help to explain terminal moraine.

Although you can’t See it in this picture The terminal moraine is Blocking this valley and causing The lake. Formation of a Moraine dammed lake

? This lake is far deeper than the land after the rest of the valley. How do you think this is possible? What did the glacier do here?

Formation of a moraine dammed lake A glacier moves down a valley over hard rock eroding it. The glacier moves onto an area of soft rock and the process of abrasion is much greater. The soft rock is deepened much more than the hard rock. The glacier moves onto another area of hard rock and pushes moraine in front of it. When the glacier melts the terminal moraine acts as a dam and creates a ribbon lake. It is called a ribbon lake due to the fact it is long and thin.

Formation of an Esker Esker

Formation of an Esker How do you think this esker was formed?

Formation of an Esker Clue: An esker is a steep-sided, long, winding ridge, made up of gravel and sand.

Glacial streams are found under the ice-sheet.They are loaded with debris (sand and gravel) carried by the meltwater. As the ice-sheet retreats, the river deposits its load.

Formation of an esker. An esker is a steep-sided, long, winding ridge, made up of gravel and sand. It is formed when a river of melt-water runs through a glacier. The river deposits sorted material that it can no longer carry. The material is small and rounded by the water. When the glacier melts the river is also lost from the landscape and the esker is left.

The outwash plain Direction of Glacier Terminal moraine The outwash plain

The outwash plain is formed from melt water after a glacier begins to retreat. It almost always comes after terminal moraine. It is made up of fine sands and gravel. The material is sorted as it is created carried by water. It is not very fertile.

Formation of Kettle holes This is a kettle hole. It is a fairly shallow circular pool of water on a glaciated landscape

Formation of Kettle holes You will often find a few of them together on the landscape The mystery is how were they formed? You have 3 minutes to come up with an idea.

Formation of a Drumlin

Formation of Drumlins. Drumlins are large mounds of unsorted material left on landscaped by glaciers (1). The exact reason that drumlins are left on the landscape is unknown but they are often found at the front of glaciers and would have been deposited when the glacier lost the power to transport material (1). The drumlins show the direction that the glacier was moving because the wide, steep end points in the direction the glacier came from and the long narrow end shows the direction the glacier was going (2). Drumlins are often found in large groups (1).

What direction was the Glacier moving? Give evidence for this 5 KU. West East Boulder Clay Sands and gravel

What direction was the Glacier moving? Give evidence for this 5 KU. Model answer.

Boulder Clay Sands and gravel Unsorted rocks: terminal moraine

Boulder Clay Sands and gravel Unsorted rocks: terminal moraine Crop farming Forestry Pastoral farming

Land use: See PP “Land use in Glaciated uplands”