In this Grade 6 Earth Science lesson from Chapter 6: Plate Tectonics, students learn to identify the three types of tectonic plate boundaries — divergent, convergent, and transform — with a focus on what happens when plates move apart at divergent boundaries. Students explore how mid-ocean ridges and rift valleys form as molten material rises to create new crust at spreading centers, and investigate magnetic reversal to understand how scientists measure the direction and speed of plate movement. The lesson builds on prior knowledge of sea-floor spreading and the theory of plate tectonics.
Section 1
Tectonic Plates Move Apart to Form New Crust
When tectonic plates move away from each other at divergent boundaries, magma rises to fill the gap, creating new crust. In oceans, this forms mid-ocean ridges and rift valleys, while on land it splits continents apart.
Section 2
Magnetic Reversals Record Plate Movement on the Sea Floor
As new oceanic crust forms at mid-ocean ridges, tiny magnetic minerals align with Earth’s magnetic field. When the field reverses, newly formed rocks record the change, creating a striped pattern that reveals how plates have moved.
Section 3
Hot Spots Help Scientists Measure Plate Movement
Hot spots are stationary columns of rising magma. As plates move over them, chains of volcanoes or islands form. By tracking the locations and ages of these landforms, scientists can measure the speed and direction of plate movements.
Section 4
Scientists Use Technology to Track Plate Movements
Lasers and satellites or GPS are used to measure distances between points on Earth’s surface. By monitoring changes over time, scientists accurately track how far and how fast tectonic plates move apart each year.
Section 5
Rift Valleys Sink and Fill With Water as Continents Split
As continental plates move apart, the crust stretches, thins, and sinks, forming a rift valley. If the valley sinks below sea level, water enters and eventually creates new seas or lakes, like the widening Red Sea.
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Section 1
Tectonic Plates Move Apart to Form New Crust
When tectonic plates move away from each other at divergent boundaries, magma rises to fill the gap, creating new crust. In oceans, this forms mid-ocean ridges and rift valleys, while on land it splits continents apart.
Section 2
Magnetic Reversals Record Plate Movement on the Sea Floor
As new oceanic crust forms at mid-ocean ridges, tiny magnetic minerals align with Earth’s magnetic field. When the field reverses, newly formed rocks record the change, creating a striped pattern that reveals how plates have moved.
Section 3
Hot Spots Help Scientists Measure Plate Movement
Hot spots are stationary columns of rising magma. As plates move over them, chains of volcanoes or islands form. By tracking the locations and ages of these landforms, scientists can measure the speed and direction of plate movements.
Section 4
Scientists Use Technology to Track Plate Movements
Lasers and satellites or GPS are used to measure distances between points on Earth’s surface. By monitoring changes over time, scientists accurately track how far and how fast tectonic plates move apart each year.
Section 5
Rift Valleys Sink and Fill With Water as Continents Split
As continental plates move apart, the crust stretches, thins, and sinks, forming a rift valley. If the valley sinks below sea level, water enters and eventually creates new seas or lakes, like the widening Red Sea.
Book overview
Jump across lessons in the current chapter without opening the full course modal.
Continue this chapter