Lecture Notes: Barrier Islands, Hurricanes, and Sea Level Changes

Barrier Islands and Hurricanes

• Location: North Carolina with a focus on Ocracoke (pronunciation uncertain).
• Example: Hurricane Isabel
  • Path through the barrier island.
  • Impact: Created Isabel Inlet and beach by ripping and depositing land.
  • Result: Increased migration rate of barrier islands inland.
• Consequence: Hurricanes accelerate the movement of barrier islands by creating new inlets.

Blackbeard and Barrier Islands

• Historical Context: Blackbeard, a famous pirate, exploited limited inlets for piracy.
• Strategy: Used inlets known for shipping to intercept and steal shipments.

Gulf Coast and Barrier Islands

• Focus Area: Padre Island National Seashore
  • Salinity: High salinity lagoon, over 50 parts per thousand.
  • Ecology: Home to Kemp’s ridley sea turtle, one of five threatened and endangered species found here.
  • Biodiversity: Supports five of the world’s seven sea turtle species.

Deltas

• Formation: Occur where there is low wave activity and small tidal range.
• Example: Mississippi River Delta
  • Formation through sediment compaction and subsidence causing plate sinking.
• Video Explanation: Innies and outies analogy for river mouths.
  • Key Idea: Sediment accumulation forms new land, fostering fertile deltas.
• Historical Context: Estuaries and deltas formed about 7,000 years ago due to sea level stabilization.

Global Sea Level Changes

• Factors:
  • Ice Volume: Changes up to 120 meters (400 feet) due to ice ages.
  • Thermal Expansion: Warmer temperatures cause water to expand, contributing to sea level rise.
  • Seafloor Spreading Rates:
    • Fast spreading leads to large magma chambers under mid-ocean ridges.
    • Effect: Lifts seafloor, causing water displacement and sea level rise.

Conclusion

• Understanding barrier islands and delta formation is crucial for comprehending coastal changes.
• Sea level changes are influenced by natural processes like ice volume, thermal expansion, and seafloor spreading, impacting global coastlines.