Year 8 Science · Unit 3 · Lesson 21
Challenge Worksheet
Learning Goals
Compare two (plus one)
Complete the table to compare the three types of plate boundaries. Fill in all blank cells.
| Feature | Convergent boundary | Divergent boundary | Transform boundary |
|---|---|---|---|
| Direction of plate movement | |||
| Landforms created | |||
| Geological hazards | |||
| Real-world example |
What if…?
Scenario
Australia currently moves north at approximately 7 cm per year, driven by mantle convection beneath the Indo-Australian Plate. Imagine that the convection currents in the mantle beneath Australia suddenly stopped completely, the plate is frozen in place. Consider what would happen geologically, environmentally, and climatically over the next 10 million years.
(a) Geological consequences, What would happen to the plate boundary processes near Australia (e.g. subduction zones to the north, spreading ridges to the south)? Would mountain building in the Himalayas continue?
(b) Environmental consequences, Australia's position affects its ocean currents and rainfall patterns. If the plate stopped, how might the environment change? Use at least one specific example.
(c) If convection in the mantle stopped everywhere on Earth, not just under Australia, what would eventually happen to all plate boundaries globally? What would Earth's surface look like after hundreds of millions of years?
1. Paleomagnetic stripes on the ocean floor are symmetric on either side of mid-ocean ridges. Explain what causes these stripes and what they prove about plate tectonics.
2. The Glossopteris fern fossil is found on every southern continent, South America, Africa, Australia, Antarctica and India. Explain how this is possible using plate tectonics, and why this evidence was more convincing than the jigsaw fit of coastlines alone.
Wrap Up
In one sentence, what was the main idea of this lesson?