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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
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