1. 1A2 Geography 24 February, 2015 Objectives: To introduce students to a case study on a volcanic eruption in North America – Mount St. Helens.

2. Homework Textbook, page 79, question 2.

3. Homework for today’s class Textbook, page 79, question 1 (i) & (ii).

4. Advantages of volcanic activity During yesterday’s class, we listed some of the ways in which a region can benefit from volcanic activity. Can you remember some of the benefits discussed? 1.Land creation. 2.Fertile soil. 3.Geysers/geothermal energy. 4.Tourist attractions.

5. Disadvantages of volcanic activity We also listed some of the disadvantages associated with volcanic activity in a region. Can you remember these? 1.Loss of life. 2.Destruction of property. 3.Emission of toxic gases – sulphur dioxide. 4.Creation of lahars – rivers of boiling mud formed from the combination of lava and snow.

6. Mount St. Helens You are about to view two videos illustrating the effects of a volcanic eruption that occurred at Mount St. Helens, in North America, more than 30 years ago. Watch the recordings carefully. Has the volcanic eruption produced positive or negative effects. Make points to support your answer.

7. Mount St. Helens https://www.youtube.com/watch?v=- H_HZVY1tT4 https://www.youtube.com/watch?v=- H_HZVY1tT4 https://www.youtube.com/watch?v=njV9ski1 gB4 https://www.youtube.com/watch?v=njV9ski1 gB4

8. Mount St. Helens Based on what you have seen, do you think that the volcanic eruption at Mount St. Helens has produced positive or negative effects on the surrounding region? Give reasons for your answer.

9. Mount St. Helens An eruption at Mount St. Helens on the 18 th May 1980 had a devastating effect on the surrounding region. (Worst volcanic eruption in US history.) There was loss of life. Between 50-60 people were killed. 7000 large animals and hundreds of smaller creatures also died. lahar There was massive destruction within a 300km² area of the mountain. Forests were destroyed. 200 homes were also ruined by a lahar.

10. Mount St. Helens March 1980: Earthquake under mountain. April 1980: Bulge formed on the mountain’s side and grew daily. May 18 th 1980: Eruption. Avalanche of rock and hot ash down mountain. Ash cloud reached a height of 10 miles. The eruption lasted 9 hours approx.

11. 1A2 Geography 24 th February, 2015 Objective: To introduce students to fold mountains, and discuss their formation. To introduce students to periods of folding.

12. Tectonic Plates Earth’s crust is not one whole piece, it is divided into sections called plates. There are two types of tectonic plate, continental and oceanic. Continental plates are located under land masses (e.g. Eurasian plate, African plate). Oceanic plates are located beneath the seas (e.g. Pacific plate).

13. Fold Mountains Fold mountains are formed when land buckles at destructive plate boundaries (i.e. where plates collide).

14. Formation of Fold Mountains If an oceanic plate meets a continental plate at a destructive plate boundary, part of the oceanic plate will sink below the continental plate and descend into the mantle. The oceanic plate will sink because it is heavier. See Fig. 4.18 page 74.

15. Formation of Fold Mountains fold mountains As the oceanic plate sinks, the continental plate buckles upwards, causing fold mountains to form. The part of the oceanic plate that descends into the mantle melts to form new magma. This can move to the surface, forming volcanoes.

16. The Andes The Andes, a mountain range stretching through several South American countries, are an example of fold mountains. The Andes formed when the Nazca (oceanic) plate collided with South American (continental) plate.

17. The Andes Snow-capped mountainsNevado del Ruiz

18. Formation of Fold Mountains If two continental plates meet at a destructive plate boundary, both will buckle upwards. For example, the Himalayas have formed where the Indo-Australian plate is colliding with the Eurasian plate. Mt. Everest, which is part of the Himalayan mountain range, was formed in this way, and continues to grow higher as these plates continue to buckle upwards.

19. Anticlines & Synclines Anticline: This is an up- fold. Syncline: This is a down- fold.

20. Himalayas Video https://www.youtube.com/watch?v=PDrMH7 RwupQ https://www.youtube.com/watch?v=PDrMH7 RwupQ https://www.youtube.com/watch?v=HuSHOQ 6gv5Y https://www.youtube.com/watch?v=HuSHOQ 6gv5Y

21. Fold Mountains: Periods of Folding Fold mountains are categorised according to the time period in which they formed. Categories of fold mountains include Alpine and Armorican.

22. Fold Mountains: Alpine Alpine Fold Mountains formed 30-35 million years ago. Examples can be found on four continents. Alps, Europe; Himalayas, Asia; Rockies, North America; Andes, South America.

23. Fold Mountains: Armorican Armorican Fold Mountains formed approximately 250 million years ago, when the Eurasian plate was colliding with the African plate. Fold mountains in Ireland formed during the Armorican period include the Macgillicuddy’s Reeks, the Galtees, the Comeraghs, and the Knockmealdowns.