1. Layer Thickness (km) Temperature (°C) Composition
Inner 1 370
Mostly Fe, Ni,
Core 3 000 to 5 000
forming an alloy
Outer 2 100
Mixture of solid
Mantle 2 900 1 400 to 3 000 and molten rocks
(magma)
Less dense
Continental 10 to 70
minerals (eg. Al)
Crust -14 to 1 200
Denser minerals
Oceanic 5 to 10
(eg. Mg)
Tectonic plates
Continental plate Oceanic plate Major plate Minor plate
1. North American 1. Nazca 1. North American 1. Nazca
2. South American 2. Pacific 2. South American 2. Philippine
3. African 3. Philippine 3. African 3. Cocos
4. Eurasian 4. Cocos 4. Eurasian 4. Caribbean
5. Indo-Australian 5. Caribbean 5. Indo-Australian 5. Scotia
6. Antarctic 6. Scotia 6. Antarctic
7. Pacific
Divergent Convergent Transform
Oceanic – Oceanic Oceanic – Oceanic Transform fault
Forms a mid-oceanic ridge Forms undersea volcanoes, (eg. San Andreas Fault)
(eg. Mid-Atlantic Ridge) oceanic trench and volcanic
islands (eg. Mariana Trench, When plates slide past each
Formation: Islands) other, a transform boundary is
Rising and spreading convection formed. This often results in
currents in the mantle cause the Formation: earthquakes.
(Plate name) and (Plate name) to Cooling and sinking convection
move away from each other. As currents in the mantle cause the
the plates move apart, tensional (Plate name) and (Plate name) to
stresses cause fractures in the move towards each other and
lithosphere. New basaltic converge. The denser oceanic
magma wells up at the spreading plate is subducted under the
centre where it cools and less dense continental plate.
solidifies to form new sea floor. The sinking crust is melted in the
magma due to immense pressure
and heat. Less dense silica-rich
magma then rises thru fractures
in the crust to pour onto the
ocean floor, forming undersea
volcanoes. When they are built
up and appear above the sea, they
form volcanic islands.

2. Continental – Continental Continental – Continental
Forms rift valleys Forms fold mountains
-
Formation: Formation:
REFER TO CHAPTER 4. REFER TO CHAPTER 4.
Oceanic – Continental*
Forms subduction volcanoes,
oceanic trench, fold mountains
Formation:
Cooling and sinking convection
currents in the mantle cause the
(oceanic plate name) to converge
and collide with the (continental
plate name). The denser (oceanic
plate name) subducts under the
lighter (continental plate name),
forming a narrow, linear depress-
ion parallel to the boundary -
called an oceanic trench. The
subducted part of the (oceanic
plate name) melts due to
immense friction and heat in the
mantle. The less dense silica-rich
magma then rises thru fractures
on the surface where it cools and
solidifies to form subduction
volcanoes. Due to compression
of the rock strata of the (contin-
ental plate name), the rock strata
are bent, uplifted and contorted
to form fold mountains.
Formation of subduction volcanoes, fold mountains and oceanic trench