Geological Features at Divergent Plate Boundaries

Introduction

• Focus on geological features at divergent plate boundaries.
• Divergent boundaries: plates move away from each other.
• Creation of new land observed at mid-oceanic ridges.

Correction from Previous Video

• Clarification on diagram arrows: should indicate direction into the page.

Layers of the Earth

1. Crust
   • Can be continental crust.
2. Lithosphere
   • Combination of crust and solid part of the mantle.
3. Mantle
   • Liquid (magma) that is super hot.

Hot Spots Formation

• Debate on hot spot formation:
  • Could arise from mantle plumes or convection currents in the mantle.
• Assume hot spots form in the mantle to facilitate further discussion.

Process of Divergence

Step 1: Hot Magma Rising

• Hot magma becomes less dense, allowing it to rise due to buoyancy.
• Heat from magma melts through lithosphere, creating a hot spot.

Step 2: Formation of a Dome

• Hot magma creates a dome in the lithosphere and crust.
• Rigid materials (lithosphere) crack under pressure—similar to sourdough bread.

Step 3: Rift Formation

• As magma rises, it pulls the crust apart, creating a rift valley.
• Example: African Rift Valley.

Step 4: Below Sea Level

• Continued stretching may lead to rift valleys being below sea level.
• Example: Formation of the Red Sea between African and Arabian plates.

Step 5: Creation of Mid-Oceanic Ridges

• As rift valleys depress, water can flow in, forming oceans.
• Mid-oceanic ridges created by underwater volcanoes from hot spots.
• Example: Mid-Atlantic Ridge.

Conclusion

• Understanding why we see uplifted land at divergent boundaries while surrounding areas are lower.
• Analogy of bread to visualize geological processes.