Lecture Notes: Subtropical Oceanic Gyres and Coastal Landforms

Subtropical Oceanic Gyres

• California Current

  • Part of the North Pacific Subtropical Oceanic Gyre.
  • Runs from higher latitudes back to the equator.

• Gulf Stream

  • Part of the North Atlantic Subtropical Oceanic Gyre.
  • Runs from the equator to higher latitudes, bringing warmer water up north.

Longshore Transport

• Directional Flow
  • East Coast storms originate from the North Atlantic.
  • West Coast storms originate from the North Pacific.
  • Longshore current direction is north to south on both coasts.
  • Sand transport along the Atlantic and Pacific coasts is southward.

Beach Compartments

• Components

  1. Rivers supply sediment.
  2. Sand is swept down the coast by the longshore current.
  3. Sand ends in submarine canyons.

• Examples

  • Santa Barbara compartment: Point Conception to Waimea or Magu Canyon.
  • Santa Monica compartment: Ends at Redondo Canyon.
  • San Pedro compartment: Starts in LA, ends at Newport Canyon.
  • Oceanside compartment: Dana Point to La Jolla Canyon.

Depositional Landforms

• Deltas

  • Formed by river sediment deposition in low-wave areas.
  • Example: Large delta in Canada.

• Spits

  • Formed by longshore drift.
  • Shape indicates longshore current direction.
  • Salt marshes often form behind spits.

• Bay Barriers (Bay Mouth Bars)

  • Form when spits extend across a bay.
  • Create lagoons that become saltier over time.

• Tombolos

  • Form behind islands where waves are blocked.
  • Sand builds up in low-energy environments akin to summertime beaches.

Observations and Examples

• Gulf of California

  • Noted for low-energy, depositional landforms.
  • Locations like Moulihae and Loreto showcase these features.

• Class Note

  • Students are encouraged to contribute photos of these landforms, particularly from places like the Gulf of California.