1. CH 16 The Dynamic Ocean
Ocean water is in constant motion and powered by many forces
Forces include wind, Coriolis, gravity, density differences
Ocean currents are masses of ocean water that flow from one place to another
Surface or deep

2. Surface Currents Movements of water that flow horizontally
Develop from wind friction
Gyres = huge circular moving current systems (5)
Coriolis Effect = the deflection of currents to the right in the NH (& left in the SH) due to earth’s rotation
Warm currents move from the equator to the poles
Cold currents move from polar regions to the equator
Cold currents = west coast; warm currents = east coast

3. Deep Ocean Circulation
Vertical movement of water
Upwelling = cold water rising from deep layers to replace warm surface water
Brings nutrients to surface(good for fishing)
Density currents = vertical currents of water due to density differences
From temperature(cold) and salinity (high)
Read pages 451 – 453

4. Waves Most waves obtain their energy and motion from wind
Big wind = big waves
Crest = top
Trough = bottom
Wave height = distance from trough up to crest
Wavelength = distance from crest to next crest
Wave period = time it takes a full wavelength to pass a fixed position

5. Height, length, & period of waves depends on 3 factors:
1. Wind speed
2. Length of time the wind blows
3. Fetch (distance across body of water)
The only thing that really moves forward in a wave is energy(particles move in circular orbital motion)
Breakers--Waves that break (fall forward) when the depth of the water is one-half of the wavelength.

6. TIDES
Tides are daily changes in the elevation of the ocean due to the gravitational attraction of the moon & sun.
Most places have 2 high & 2 low tides each day.
Tidal Range=difference in height of high & low tide.

7. 2 TIDE TYPES & 3 TIDE PATTERNS
SPRING= full & new moon, largest tidal range, moon-earth-sun are all in a straight line.
NEAP= 1st & 3rd quarter moons, smallest tidal range, moon-earth-sun at 90 degree angles.
3 TIDE PATTERNS: (read about them)
diurnal = 1 hi & 1 low per day
semi-diurnal = 2 hi & 2 lo per day (fairly equal)
mixed = 2 hi & 2 lo per day (unequal)

8. SHORELINE PROCESSES/FEATURES
BEACH=accumulation of sediment along shores. (white,pink,tan,black,green)
SHORELINE (WAVE) FORCES:
Eroding
Transporting
Depositing
Wave impact
Abrasion
Refraction = bending of waves

9. Wave energy is concentrated at headlands = more erosion
Wave energy is weakened in bays = more deposition
Longshore current = sediments carried along (parallel) to shore due to waves hitting at an angle.

10. EROSIONAL FEATURES: Sea Cliff – result from waves cutting at the base
Sea Cave – from softer rock being eroded
Sea Arch – cave all the way through
Sea Stacks – roof of the arch collapses
Wave-cut platform or terrace – from continued wave action causing a flat eroded area

11. DEPOSITIONAL FEATURES:
Spit – elongated ridge of sand sticking into the bay
Hook – when the spit hooks due to currents
Baymouth Bar – when a sand bar completely crosses the bay
Tombolo – a ridge of sand that connects an island to the mainland
Barrier Islands = (Outer Banks)

12. Stabilizing/protecting shores:
Jetties or groins –barrier built at right angles to the beach to catch sand
Breakwaters – offshore and parallel to coast
Seawalls – parallel to coast often from the shore
Beach nourishments
Natural protectors: sand bars, sand dunes, fringing reefs, barrier reefs, & atolls