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Elective Geog (New)Secondary 3NWeek 6: Living with Tectonic Hazards

2+Worksheet 1: Review

Question 1 It is not a natural hazard as it is 6000km away And a naturally occurring event is only a hazard when

lives are affected and when properties are destroyed.

Question 2 Convection currents are movements of heat within

the mantle Material in the mantle is heated by the core, causing

the mantle material to expand, rise and spread out beneath the plates

This causes plates to be dragged along and to move away from each other

Then the hot mantle material cools slightly and sinks, pulling the plate along

+Worksheet 1 Review: Understanding Command WordsDescribe

Give a written factual account of the distinctive features of an item

Describe the differences Compare

+Worksheet 1 Review:Understanding Command WordsCompare

Provide a point by point account of the similarities and differences between two sets of information or two areas

Must use comparative adjectives (eg. Larger than, smaller than, more steep than)

Two sets of descriptions does not make a comparison May be written as “Describe/ List/ Identify the main

differences/ similarities”

5+Worksheet 1 Review:

Question 3 Oceanic crust is found beneath deep oceans while

continental crust is found beneath earth’s continental masses and under shallow seas close to continents

Oceanic crust has a thickness of between 5 and 8km which is thinner than the continental crust which has a thickness of between 30 and 60km

Oceanic crust is heavier and denser than the continental crust.

Oceanic crust consists mainly of basalt while a continental crust consists mainly of granite

Use of comparatives

6+Worksheet 1 Review:Understanding Command WordsWith a well annotated diagram

Add notes of explanation Label with short comments a diagram to describe Only the diagram and attached notes will be marked

7+Important Note!

Plates are NOT continents

Plates include both continental and oceanic crust.

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Elective Geog (New)Secondary 3NWeek 6: Living with Tectonic Hazards

9+Lesson Outcomes

By the end of the lesson, we will be able to describe the global distribution of tectonic plates and types of plate boundaries.

10+Types of Plate Boundaries

11+Different types of plate boundaries

Divergent: where plates move away from each other

Convergent: where plates move towards each other

Transform: where plates move past each other

12+Note areas with earthquakes & volcanic activities

13+Divergent Plates

Areas where two plates move away from each other

Magma moves upward to the surface where it cools to form new oceanic crust along these boundaries Oceanic-oceanic Continental-continental

14+Oceanic-oceanic

Magma rises from the mantle to fill the gap between the plates as they

diverge.

New sea floor is formed when the magma cools and solidifies. This process is called sea-floor spreading.

Magma rises at the zone of divergence/spreading zone to form a ridge of new ocean floor called mid-

oceanic ridge.

The newly formed (youngest) rocks are closest to the middle of the ridge/plate boundaries.

At various points along the ridge, magma builds up above the ocean to form volcanic islands.

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16+Oceanic-oceanic

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18+Continental-continental

+Diverging:Continental- Continental

East AfricanRift Valley

African Plate(Nubian)

African Plate(Somalian)

Block Mountain

Block Mountain

20+Rift valleys and Block mountains

A fault Fracture in the rocks along which the rocks are

displaced Due to tensional forces

Rift Valley Is a valley with steep sides that is formed when the

sections of the crust extend along fault lines

Block Mountain A block of land with steep sides

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Afar Triangle, Triple Divergent Triangle

armanalluwie.blogspot.com

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http://www.youtube.com/watch?v=ic54PSuQwLE