Lecture Notes: Beach Formation and Erosion

Introduction

• Exploration of why beaches look the way they do
• Influence of human activity on natural beach systems

Case Study: Swami's Beach

• Location: Encinitas City Beach
• Features:
  • Flat pieces of rock (Del Mar Formation)
  • Del Mar Formation: Mostly shale, small particles, millions of years old
  • Presence of oyster beds indicating historical lagoon environments
  • Seasonal sand fluctuation influences visibility of rock formations

Human Intervention

• Man-made rocks used to stabilize cliffs
• Purpose: Prevent erosion from high tide waves

Beach Formation Example: Scripps Beach

• North of Scripps Pier in La Jolla
• Whale Rock: Sometimes buried under several feet of sand

Beach Dynamics

• Factors influencing sand levels:
  • Seasonal changes
  • El Niño
  • Wave activity

Erosional Processes

• Pacific coast dominated by erosion
• California's tectonic activity leads to land uplift
• Result: High energy waves impact beaches

Geological Factors

• Tectonic activity causes uplift along the coast
• Influence of ice ages on sea levels
• Fault lines prevalent throughout the region

Specific Faults

• Rose Canyon-Inglewood Fault: Near La Jolla Cove
• San Andreas Fault: Extensive reach through California

Coastal Landforms

• Wave-cut Bench: Flat surface created by wave interaction
• Marine Terrace: Uplifted former wave-cut benches
• Sea Arches and Caves: Formed by waves eroding cliffs
• Headlands and Coves: Land forms protruding into ocean or retracted
• Sea Stacks: Isolated rock formations from collapsed arches

Global Examples

• Sea caves in Greece
• Sea stacks in New Zealand
• Archways in Australia

Sunset Cliffs, San Diego

• Features all discussed coastal formations
• Previously had a blow hole, now a large open view
• Popular spot for cliff jumping (not advised)

Conclusion

• Tectonics play a crucial role in shaping beaches
• Understanding geological and human factors is essential for coastal management