Lecture Notes: Yosemite Valley National Park Geology

Introduction

• Location: Yosemite Valley National Park
• Geological Interest: Part of the Sierra Nevada mountains

Geological Formation

• Type of Mountains: Not tectonic; part of a batholith
• Formation Process:
  • Jurassic period: A plate subducting off the Pacific coast
  • Creation of hot magma beneath Earth's surface
  • Notable batholiths: Idaho batholith, Coast Range batholith

Rock Composition

• Dominant Rock Type: Granite
• Other Variations: Granodiorite
• Formation:
  • Magmatic intrusion leading to granite formation
  • Magma movement through cracks and fissures

Half Dome

• Misconception: Half Dome was never a full dome
• Formation: Magma did not form a nice bubble due to its liquid nature

Geological Features

• Exfoliation:
  • Gravity causes cracks and smooth formations
  • Term used: Exfoliation joints
• Glaciation:
  • Significant glaciation in the area
  • Original batholith cooled 2 miles below ground
  • Area uplifted, with sediment eroded exposing the rock

Erosion and Waterfalls

• Waterfalls:
  • Formed by snowmelt
  • Major waterfalls: Upper Fall, Nevada Fall, Vernal Fall
  • Yosemite Waterfall: Significant flow rate
• Durability of Granite:
  • Water has not significantly eroded the V-cuts
  • Granite’s durability highlighted by continuous water flow

Conclusion

• Summary:
  • Yosemite provides insights into geological formations and processes
  • Investigations into features like exfoliation domes to be continued

Note: More details expected in a future discussion on exfoliation domes.