The Evolution of North America's Geography

Introduction

• Earth's geography is constantly changing due to tectonic plate movement.
• Focus on the formation and evolution of North America's landscape over hundreds of millions of years.

750 Million Years Ago

• Rodinia: A supercontinent begins to rift, creating the Panthalassa Ocean.
• Laurentia: An ancestral continent that grows as island chains collide and add landmass.

400 Million Years Ago - Formation of the Appalachian Mountains

• The African plate moves westward, closing the Iapetus Ocean.
• Pangea Formation: Collision with Laurentia forms the supercontinent Pangea.
• Appalachians: Pressure from collision causes faulting, folding, and formation of mountains.

100 Million Years Later - Breakup of Pangea

• Southern Atlantic Ocean Opens: Separation of the North American Plate and African Plate.
• Farallon Plate: Convergence with North America's west coast leads to subduction.
  • Subduction explains volcanic activity and formation of granite in Yosemite and Sierra Nevada.

85 Million Years Ago - Rocky Mountains Formation

• Volcanism Shifts Eastward: Due to the less steep Farallon Plate.
• Formation of Rockies: Compression from subduction results in uplift of mountain ranges.
• Eurasian Plate Rifts: Opens the North Atlantic Ocean.

Uplift and Erosion

• Colorado Plateau: Uplifts due to mantle flow and thickened North American Plate.
  • Future sculpting by Colorado River into the Grand Canyon.

30 Million Years Ago - San Andreas Fault

• Farallon Plate Subduction Completion: Mostly sinks into the mantle.
• San Andreas Fault Formation: Boundary between Pacific and North American plates.
  • Causes earthquakes and the formation of the Basin and Range Province.

15 Million Years Ago - Yellowstone Supervolcano

• Mantle Hotspot: Creates a supervolcano beneath Yellowstone.
• Supervolcano's Potential: Could cause massive eruptions affecting the continent.

Conclusion

• Earth’s plates keep the planet in constant change.
• The unpredictable future of North America’s landscape over geological time.