Y13 - 2016 (Old Spec) - A Level Geog

8th September 2016 Period 2

What are the Characteristics/Features of Different Tectonic Plate Margins?

Last piece of work set in July: HERE

Not completed/HI...  to teach.

Info: Source ppt Slides 65 to 74 deal with destructive margins.

Once completed... students should answer following (from previous work assignment):

13th September 2016 Period 6

What are the Characteristics/Features of Different Tectonic Plate Margins?(continued)

Ref Page 16 and 17 of the core text (copy previously provided)

1     Study the information about the different types of destructive plate margins.

a  What is meant by subduction and why is it an important process at destructive plate margins? (Try to place your answer into a wider tectonic theory explanation i.e. to include other types of margin and the concept in general).

b  Why is there no volcanic activity at a continental collision margin yet frequent earthquake activity?

c  Describe and explain the pattern of earthquakes at the different destructive margins. Use simple sketches to support your answer (Think about what the term “pattern” could mean in this context).

d  Imagine that you discovered a small group of islands in the Pacific Ocean. What evidence would you look for to confirm that they are an island arc and, therefore, represent a destructive plate margin? Explain your answer using diagrams to help.

e  What tectonic hazards are associated with destructive plate margins?

13th September 2016 Period 6

What are the Characteristics/Features of Different Tectonic Plate Margins?(continued)

Work originally set in July: HERE

Info: Source ppt Slides 78 to 86 deal with destructive margins.

Once completed... students should answer following (from previous work assignment):

Ref Page 18 and 19

1 Why do earthquakes occur along conservative plate boundaries, but not volcanoes?

2 Describe some of the short-term and longer-term impacts of earthquakes that have occurred along the San Andreas fault system. Research the www.

3 Why might trying to predict earthquakes be a near-impossible goal? Use information about the San Andreas fault system to support your answer.

4. Given that conservative margins do not produce volcanoes, how can the presence of so many be explained along the western margins of North America? (Include reference to actual volcanoes at different locations along this margin, relevant tectonic plates and other features that might explain the presence of volcanoes here).

1. Study Figure 1.26 next page.

a  Using Figure 1.23 and your own knowledge, label the diagram with the names of specific tectonic plates. Begin by locating New Zealand and the Andes on the map.

b  Finish your diagram by adding annotations to the suggested boxes.

2. Explain the relationship between earthquakes, volcanic activity and plate margins. Be sure to use examples in your answer.

Figure 1.23 The relationship between tectonic plate margins, earthquakes and volcanoes

Figure 1.26 Block diagram of tectonic plate margins

CW 13Gg 20th September 2016

Period 3 Title:

Review of Constructive Plate Margins

Aims:

To know the features and locations of Constructive Plate Margins and to be able to explain the processes at work...

• Knowledge of the two types of Constructive Plate Margin.

• Ability to describe the features that characterise Constructive Plate Margins.

• The ability to demonstrate understanding of the processes operating at Constructive Plate Margins with reference to specific examples.

(Ppt resource - Slide 41)

Notes from Ppt:

Constructive Margins are alternatively known as DIVERGENT margins… divergent means separating.

Two types - Determined by the types of crust involved:

• Oceanic Areas where seafloor spreading occurs on either side of mid-ocean ridges eg Mid-Atlantic ridge
• Continental Areas where stretching and collapsing of the crust creates rift valleys eg The Great African Rift Valley.

It is at the Constructive Margins that some of the planets youngest rocks are found since this is where new crust is being formed in the gap between two divergent plates is filled with magma rising from the asthenosphere. As the magma cools, it solidifies to form new dense basaltic rock.

Mid-Ocean Ridges:

• Oceanic divergence forms chains of submarine mountains snaking along the constructive margins. Regular breaks called Transform Faults cut across these ridges allowing the spreading to take place on the planets spheroidal surface.

• The Transform Faults separate sections of the mid-ocean ridges that separate at different speeds, rates and times. This leads to frictional stresses building up and shallow-focus earthquakes (at depths less than 70km) releasing this tension.

• Mid-Ocean Ridges rise up to over 4000m above the sea floor, but the middle of the ridges are marked by deep rift valleys in all but the most rapidly separating margins found in the east Pacific. Over centuries, the rift valleys are widened by magma rising from the asthenosphere, which cools and solidifies to form new crust.

• Volcanic eruptions along the ridges can build submarine volcanoes. Some of these rise above the ocean surface to form volcanic islands such as Surtsey near to Iceland.

Rift Valleys (Continental Divergence)

Continental divergence forms massive rift valleys. These are formed when the lithosphere stretches, causing the development of parallel faults. The land between the faults then collapses into deep, wide valleys which are separated by upright blocks of land called HORSTS. The valleys between are known as GRABEN.

The best known example of Continental divergence is probably the East African Rift system.

Horst/Graben system. Lateral extension and vertical displacement between parallel faults results in the formation of blocks of upland separating "blocky" valleys.

Illustration showing the relationship of parallel faulting to plate movement.

The divergence in continental regions can be seen as a continuum with oceanic divergence... the continent eventually divides sufficiently for the intervening lowlands to be flooded by the sea... NB East African Rift - Atlantic Ocean...?Continental Rifting (divergent) - Continued (Academic Uplift) There may be a relationship between plumes of upwelling magma and the initiation of Divergent Margins. In the East African example, there is a clear Triple Junction – The Red Sea/East Africa/Gulf of Aden.

it is hypothesised that a plume pushes up the crust in the region of Afar at the apex of the three rift valleys... the rift valleys are a response to the uplift and stretching of the spherical crust.

This can be simulated with a photocopied map of the region which is scored and cut along the lines of the Red Sea, and East African Rift system. A small ball, representing the rising mantle plume, placed beneath the triple point at Afar, is seen to dome up the model, the resulting tension displacing the “lithosphere” form the characteristic rifts. (below)

CW 13Gg 20th September 2016
Period 6 Title:      What are "Hot Spots"

• Knowledge of the distinguishing features of Hot Spot volcanic activity including their location.
• Ability to explain the processes responsible for hot spots.
• Demonstration of detailed knowledge of a specific hot spot (Hawaii)

From your description of the global distribution of volcanoes and earthquakes, it will be apparent that most are located along tectonic plate margins. However, there are notable exceptions to this general pattern. An example of this is the Hawaiian  Islands located in the middle of the Pacific Plate (ie away from the plate’s margins).

Radioactive decay at the core generates very high temperatures. If this decay is concentrated, hot spots develop around the core which, in turn, heat the lower mantle creating localised thermal currents where plumes of magma rise vertically.

While such plumes are usually found near to plate margins, they may occasionally form within the centres of plates where effectively “burn” through the lithosphere to create volcanic activity at the surface. 

As hot spots tend to remain stationary, the movement of the overlying plate results in the formation of a chain of active and extinct volcanoes… like the Hawaiian Islands.

Access Info about the Hawaiian Is - HERE

http://www.geolsoc.org.uk/Plate-Tectonics/Chap3-Plate-Margins/Mid-plate/Hawaiian-Islands

22/9/2016
Activities:

1. Using a simple labelled diagram, explain how a deep plume of magma at a hot spot was responsible for the formation of the chain of Hawaiian Islands.
2. Explain why hot spot volcanoes presented a problem when the original theory of plate tectonics was developed.
3. Describe and explain the changing volcanic character of islands in the Hawaiian Islands and Emperor Seamount chains.
4. How have the Hawaiian Islands been used to investigate climate change and sea level variation?

                                                          

DoE - SV7s please...

Zachary	Wingate-Denys
Pavlou-Rodriguez	Chris

CW 13Gg 27th September 2016


Period 6 
Title:      What are "Hot Spots (continued).

Complete the tasks above. (Collect in on Thursday 29th Sep 2016)

and then...

Title: 
What is Vulcanicity?

Aims:

To understand that there are different types of

vulcanicity.

To be able to describe and identify examples of

intrusive and extrusive volcanicity.

Volcanicity is commonly linked to threats and hazards, but it has provided fundamental benefits too. 

The Earth’s crust, atmosphere and water all have origins in volcanic activity. Thus we should always think of volcanicity both in terms of the benefits it provides as well as the hazards.

Defining the term: 

Volcanicity refers to all volcanic activity involving magma being forced into the crust. Usually this happens at plate margins (but not always – Hot Spots) where magma at high temperatures and pressure exploits any weaknesses in the crust and may even erupt onto the surface as lava.

Volcanic activity and features below the surface are described as Intrusive. When they erupt onto the surface, they are termed Extrusive.

In this section of your studies, you will learn about:

• Hazards and benefits of volcanicity
• Different forms of volcanic activity
• Intrusive and extrusive features
• Materials ejected from volcanic eruptions
• Different types of lava
• Volcanic landforms
• Classification of volcanoes

Watch the Video extract - HERE (Dangers and benefits).

Activity - HERE - Hazards and Benefits of vulcanicity.

PO materials from Ppt and deliver lesson from slide 119 ish

Hot Spots work to... (Collect in on Thursday 29th Sep 2016)
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4th October 2016

Collect Hot Spot activities from 22nd Sept.
Wider Reading - HERE Access the referenced links too.

Mantle plume: Definition and Explanation - HERE (This will stop midway as it is a commercial site and wants you to subscribe... but watch up to that point).

Recommended read: HERE (Discussion of the Mantle Plume theory and critique by Sara Pratt).

Fb Conservative Margins work.

1. Classification of Volcanoes - Assignment (Slides 116 to 120 Legacy Ppt)

2. Socrative test Classification of Volcanoes (13298746) - Hard Copy Here

3. Socrative test Intrusive and Extrusive volcanicity (12941700) - Hard Copy Here






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13th October 2016



Review of flipped learning:







Title:
Exam practice/preparation - Section A of Unit 4

Exam Question "Walk through":
Structured question from section A of paper/unit 4 - HERE



Case Study Prep. for NL:

Volcanic Eruption - Montserrat (LIC)
View the following video sources about the eruption of Montserrat:
HERE and HERE

Core details to know... when, where and what type of volcano?

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CW 18th October 2016

Title:
Volcanic eruption case studies - Montserrat and Mt Etna

CW 20th October 2016

Examination Question Review/Discussion (Mayon Volcano)

Resources - HERE

HI - Missing work and previous Exam Practice Question.

HW - Full review and consolidation of Half Term's work in preparation for timed essay practice in AutumnTerm 2.


CW 1st November 2016

Minor forms of extrusive volcanic activity

Even in areas where vulcanism does not generate active volcanoes, sub-surface high temperatures caused by the presence of magma or super heated ground water forced upward by convection can heat water derived from near the surface that has seeped to greater depth in the crust. The heating and expansion of this water can, in certain circumstances periodically lead to the sudden release of steam and hot water.

A geyser, the most well known of these minor forms of extrusive activity, is an intermittent turbulent discharge of superheated water ejected and accompanied by a vapour phase. Where hot water on its way upwards mixes with muds near the surface, a bubbling, boiling mud volcano may form.

In some places hot springs have become tourist attractions: in Pamukkale (Turkey), dissolved salts from the hot water are laid down in spectacular calcium carbonate deposits, though the area is not volcanically active. Places like Yellowstone National Park, USA, and Rotorua, NZ, are renowned for their geysers, hot springs and mud pots.

How a Geyser works - HERE

How a Geyser works (more complex) - HERE

Using the map below, describe the distribution/location of some famous geothermally active regions of the world, explain the causes of their activity and obtain a photo illustrating an example of minor extrusive activity at each place (try to find different types of minor volcanic activity).

Timed Essay - In Class/17th November 2017:

"Super volcanoes pose more threat to Earth and the survival of humans than asteroids, earthquakes, nuclear war and global warming".

Evaluate the threat posed by a VEI 8 "super volcanic" eruption.

15 marks

CW                                           22nd Nov 2016
P3: 

Earthquake Mitigation
Case studies - L'Aquila and Haiti + Summative comparison.

P6:
Review/feedback re. 15 mk essays... Best grades are around 9 or 10 out of 15... so, why?

Largely it is due to the way that the essays are structured and developed. Prior to writing, you need to spend time composing ie planning... so, if you re-wrote the essay, how would your begin?

1. Consider the command word/s... what does it mean and actually require you to do?

What next?

2. Define your terms... in this case a "VEI 8" volcanic eruption...

Then...

3. Set out the essential content. In the example above, this is the Impacts (at different scales... spatially ie local, national and global) and Mitigation. These are good areas to consider as the threat depends on the impacts and the impacts will vary depending how far away the eruption is. This provides opportunity to make statements about degree of threat eg from total devastation to significant disruption but evaluated in the context of scale... 

Mitigation adds a further string to your evaluation since for an event like a VEI 8, the period between eruptions and the probability of one taking place in the relatively near future are difficult to quantify beyond averages. As such, there is probably little specific planing or preparation taking place... thus the threat may be viewed as remote in likelihood but devastating if it actually happens... 

4. Review your ideas above... do you have good candidates for your basic essay structure i.e. Intro, Main and Conclusion?


Collect HW essay plan (re below).

Tsunami...

HW Assignment:

‘Systems of prediction, preparation and prevention are so well developed, catastrophe is avoidable.’ In the context of volcanic hazards, discuss the extent to which you agree with this view. 

[40 marks]