Lecture Notes: Relative Sea Level and Coastal Processes

Global vs. Local Changes

• Global Changes: Overarching climatic and environmental changes affecting sea levels worldwide.
• Local Tectonic Processes: Cause variations in relative sea level due to earth's movements.

Relative Sea Level

• Active Plate Margin (California)

  • Land rises, making it seem like sea level decreases, but it's actually land movement.
  • Misinterpretation by some as evidence against global warming.

• Ice Loading

  • Weight of ice can depress tectonic plates, making sea levels appear to rise.
  • Analogy: Jumping on an ice cube makes the water seem higher.

• Glacial Rebounds

  • Post-glacial uplift, such as at Acadia National Park in Maine, shows rising land, giving the appearance of lowering sea levels.
  • Isostatic equilibrium: Balance achieved as land rebounds after weight removal (e.g., ice).

Specific Examples

• North Atlantic Coast: Glacial rebound causing apparent sea level drop.
• Historical Context: 20,000 years ago during last glacial maximum, extensive ice cover.

Shoreline Features

• Marine Terraces: Found in the Pacific.
• Drowned River Valleys: Found in the Atlantic due to rising sea levels.
• Barrier Islands: Located in both Atlantic and Gulf.
• Emergent Coasts: In the Pacific due to tectonic activity.
• Sea Stacks and Arches: Common in the Pacific.
• Deltas: Occur in the Gulf due to lack of waves.

Hard Stabilization

• Purpose: To protect the coast from erosion.
• Examples of Hard Stabilization: Sea walls, breakwaters, use of riprap.
• Alternative: Beach nourishment.

Summary

• Understanding how local and global processes affect sea level.
• Importance of critical thinking to evaluate evidence and claims.
• Key coastal features and how they relate to sea level changes.

Announcements:

• Reach out with questions via email.
• Focus on finishing the semester strong.