Oceans, wave dynamics, coastal geomorphology.

1. Coastal Geomorphology:
The Oceans, Coastal
Processes, and Landforms
Chapter 13

2. Characteristics of Ocean Water:
Salinity, Temperature, and Density

3. Warm and Cold Ocean Currents

4. The Movements of The Oceans
•Tides
•Currents
•Wave motion

5. Tides
•A “bulge” in the world’s
oceans, caused by the
gravitational pull of the
moon and sun
Fg = G m1 m2
d2

6. Tides
• Tidal range—the difference
between high and low tide
• Affected by the shape of the
coastline and seafloor
• Spring tides—highest tides,
strong and quick
– Occur when sun, moon, and
Earth line up (the sea
“springs” up and back)
• Neap tides—lowest tides
– Sun and moon at right angles
with respect to Earth
– Neap = A low incline of bend
(when graphed)

7. Monthly Tidal Cycle

8. Extreme High Tides
• The Bay of Fundy
• A 50’ (15m) tidal fluctuation
is common (x2)
•A tidal bore (several in. to
several ft. high) rushes miles
up the Petitcodiac River in
New Bruswick

9. Landforms shaped by extreme tides

10. Extreme tides: Mont Saint Michel, France
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Low tide High tide

11. Currents: Thermohaline Circulation

12. Currents: Surface

13. Waves and Wave Dynamics

14. Waves and Wave Dynamics
•Period—The time it takes two successive
waves (from crest to crest, or from trough to
trough) to pass a given point
•Fetch—The distance over which the wind
blows, creating waves

15. Waves and Wave Dynamics
•Factors affecting open ocean waves:
–Fetch
•The greater the distance over which the wind blows,
the larger the waves
–Wind strength
•The stronger the wind, the larger the waves
–Wind duration
•The longer the wind blows, the more waves will be
created

16. Waves and Wave Dynamics
Wave base

17. Wave Base = 1/2 wave length
Wave base

18. Waves of Oscillation vs. Translation
Waves of oscillation
Waves of translation

19. Waves of Oscillation (Transition)
and Waves of Translation

20. Wave Break

21. Wave Refraction,
Longshore Current and Beach Drift

22. Erosional Environments
•If there is not enough sediment replacing what’s
being lost through wave erosion/longshore current,
erosion will occur, creating a rocky coastline
–Dammed or channelized streams
•sediment can’t get to the beach
•Erosive environments create distinctive landforms
–rocky headlands and pocket beaches, sea arches and
sea stacks, wave-cut cliffs, wave-cut platforms, wave-
built terraces, etc.

23. Wave Energy is Concentrated at
Headlands and Dissipated in Bays

24. Wave Motion and Wave
Refraction

25. Wave Motion and Wave
Refraction

26. Laguna Beach, CA
Headlands

27. Headland Erosion
and the Formation of Sea Arches

28. Stacks and Cliffs
Victoria, Australia

29. The Holderness Coast is one of Europe's fastest eroding coastlines. The
average annual rate of erosion is around 2 metres per year. The main reason
for this is because the bedrock is made up of till. This material was deposited
by glaciers over 18,000 years ago.

30. Erosional Environments:
Shoreline Retreat

31. Depositional Environments:
Welcome to the Dunes…Now Get Off!

32. The Structure of a Beach

33. Common Depositional Landforms

34. Barrier Island Structure

35. Lagoons, Marshlands, and the
Formation of New Coastlines

36. Submergent Coastlines
Ria Coast
Fjord Coast

37. Emergent Coastlines

38. Formation of a Wave-cut Platform
and Uplifted Marine Terraces

39. Formation of a Wave-cut Platform
and Uplifted Marine Terraces

40. Formation of a Wave-cut Platform
and Uplifted Marine Terraces

41. Barrier Island Coast
46
Padre Island, Texas

42. Coral Coast

43. Formation of an Atoll

44. Formation of an Atoll

45. Formation of an Atoll

46. Coral Coast

47. “Any serious researcher would be hard-
pressed to find a marina, a sea wall, or any
other human structure along the shoreline that
does not pose some long-term deleterious
effects to both the natural and cultural
environments it attempts to protect.”
--Physical Geography: Earth’s Interconnected Systems
Angela Orr, 2007
Coastal Stabilization and
Human Impact

48. Coastal Stabilization and Human
Impact
•Damming and channelizing streams
–Causes a loss of sediment where streams empty into
the sea. Without sediment, the beach will erode
away.
•Groynes (groins)
•Seawalls
•Breakwaters and jetties
53

49. Coastal Stabilization Structures

50. Groynes (groins)

51. Groynes (groins)

52. Coastal Stabilization Structures:
Breakwater

53. Marina del Rey