1. What is the plate tectonic theory?
1. Plate tectonic theory
a) Earth’s internal structure consists of core, mantle and crust, including continental and oceanic crusts
b) explains how forces within Earth drives global plate movements
2. Convection currents
a) within the hot softened mantle below the crust
b) being the driving force of overlying plates
3. Slab-pull force
a) gravity-controlled subduction of denser oceanic plate
b) drags the rest of the plate along
2. How does seafloor spreading support the plate tectonic theory?
1. Seafloor spreading
a) magma rises through mid-ocean ridges
b) forms new oceanic crusts
2. Evidence from age of rocks
a) younger rocks are found nearer to the crest of mid-ocean ridges
b) rocks get progressively older further away from mid-ocean ridges
3. Evidence from limited sediment accumulation
a) destruction of older oceanic crusts at trenches
b) oceanic crusts younger than continental crusts
3. How does magnetic striping support the plate tectonic theory?
1. Magnetic striping
a) normal and reversed polarity
b) stripes of rock on the seafloor with alternating magnetic properties
2. Evidence from rock composition
a) basalt is a volcanic rock that forms the oceanic crust
b) contains minerals that can be influenced by Earth’s magnetic field
3. Evidence from rock patterns
a) alternating polarity forms a striped pattern
b) not random or isolated occurrences
4. What will happen to different tectonic plates when they move at the different plate boundaries?
1. Divergent plate boundaries
a) plates move away from each other
b) results in mid-oceanic ridges, volcanoes including submarine volcanoes and volcanic islands, rift systems and earthquakes
2. Convergent plate boundaries
a) plates move towards each other
b) results in fold mountains, volcanoes including submarine volcanoes, oceanic trenches and earthquakes
3. Transform plate boundaries
a) plates slide past each other
b) results in faults and earthquakes
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