Presentation on theme: "Lesson 24 – pages 19-20. To learn how constructive plate margins form. To learn how mid-ocean ridges form. To learn how rift valleys form. Key."— Presentation transcript:
To learn how constructive plate margins form. To learn how mid-ocean ridges form. To learn how rift valleys form. Key Skill = Communication
Rising mantle rocks push crust up to forma a ridge. Currents pull crust apart. Crust faults an central b lock falls to form the rift. Magma squeezes up faults to create new crust. Process repeats.
Draw a labelled sketch to describe and explain the formation of a mid-ocean ridge.
Continental rift valleys form where a constructive plate margin is within a continent. The best-known example is the East African rift valley, which runs through Uganda. The continent is pulled apart by the currents in the mantle. This causes blocks to drop causing rift valleys and steep cliffs.
Plate pulls apart. Rock faults. Blocks fall Magma squeezes up faults.
Draw a sketch to show the formation of a rift valley. How did Mount Elgon form?