1. Coasts Areas where the land meets the sea…..

2. A shore (or shoreline) is the place where the land meets water (between low tide line and high tide line), but a coast includes a larger zone affected by this boundary. A beach is a zone of loose sediment that covers part or all of a shore on a depositional coast.

3. Coastal Regions/Zones Seaward – toward the sea/ocean Inland – toward the land

4. Coastal Regions/Zones Foreshore – seaward of the berm crest; active zone of the beach. Extends from beach scarp to low tide mark. –(berm crest = highest point on the beach) –(beach scarp = high tide line) Backshore – inland of the berm crest, extending to the farthest point where beach sand had been deposited

5. Coastal Regions/Zones Nearshore – area of breaking waves Offshore – area beyond breaking waves

6. Coastal Regions/Zones Beach Coast Shore Nearshore Offshore Backshore Foreshore

7. Coastal Regions/Zones Beach Coast Shore Nearshore Offshore Backshore Foreshore

8. Classifying Coasts Coasts are influenced by many factors. It is most useful to classify coasts based on predominant events that occur there, such as: Erosion Deposition

9. Classifying Coasts Another way to classify coasts is by tectonic activity. Active (active margin) Passive (passive margin)

10. Classifying Coasts A third way to classify coasts is by what is influencing or shaping them: either land processes or marine processes Primary (land processes) Secondary (marine processes)

11. Classifying Coasts The last way we can classify coasts is by changes in sea level. Emergent Coast Submergent Coast

12. EROSIONAL COASTS

13. The Twelve Apostles - sea stacks along the southern coast of Australia – are part of an erosional coast.

14. Erosional Coastlines Well-developed cliffs Recent tectonic activity (active margins) Wave erosion increases with –More shore exposed to open ocean –Smaller tidal range –Weaker bedrock

15. Features of Erosional Coastlines Headlands – areas of the shore that stick out farther than others

16. Features of Erosional Coastlines Wave-cut cliff (sea cliffs) – slope abruptly from land into the ocean; usually formed from the collapse of undercut notches

17. Features of Erosional Coastlines Wave-cut platform– smooth, nearly level terrace just offshore, marking the submerged limit of rapid marine erosion. Created by wave action

19. Features of Erosional Coastlines Sea cave – cave formed by wave action in zones of weakness in sea cliffs

20. Features of Erosional Coastlines Sea arches - a natural opening eroded out of a cliff face by marine processes

21. Features of Erosional Coastlines Sea stacks - steep column or columns of rock in the sea near a coast formed by wave action

23. Features of Erosional Coastlines Blowhole - a cavity located at the end of a sea cave which exits above the cave. When a wave enters the mouth of the cave it will be funneled up towards the blowhole, which can result in quite spectacular blasts of water from the top of the blowhole http://www.oce anfootage.com/ stockfootage/Bl ow_Hole http://www.oce anfootage.com/ stockfootage/Bl ow_Hole (Blow Hole, Hawaii Coastline)

24. Erosional Coastline Sea Cave Sea Arch Sea Stack Sea Cliff Blowhole Headland Wave-Cut Platform Beach

25. Erosional Coastline Sea Cave Sea Arch Sea Stack Sea Cliff Blowhole Headland Wave-Cut Platform Beach

26. DEPOSITIONAL COASTS

27. Depositional Coastlines Created mainly by sediment eroded from another coastline (longshore drift) Passive margins

28. Features of depositional coastlines Spit - a linear accumulation of sediment that is attached to land at one end, formed by longshore current.

29. Features of depositional coastlines Baymouth Bar (Bay barrier) – formed when a spit extends across the mouth of a bay, closing it off

30. Features of depositional coastlines Lagoon – shallow body of seawater isolated from the ocean. Formed when a bay is completely closed off by a bar

31. Features of depositional coastlines Barrier islands – narrow, exposed sand bars parallel to but separate from land

33. Inlet – narrow passage to the ocean; break in a spit or between barrier islands Features of depositional coastlines

34. Sea island – were once part of the mainland, but rising sea level has cut them off

35. Features of depositional coastlines Tombolo – bridge of sediment connecting a sea island to the mainland

36. Features of depositional coastlines Delta – coast built out by large amounts of sediment washing off land (usually from a river)

37. Features of Depositional Coastlilnes Sand Spit Baymouth Bar Barrier Island Tombolo Beach Lagoon Sea Island Inlet

38. Features of Depositional Coastlilnes Sand Spit Baymouth Bar Barrier Island Tombolo Beach Lagoon Sea Island Inlet

39. BEACHES

40. Features of depositional coastlines Beach –Backshore, foreshore, nearshore, offshore –dunes –berm –berm crest –beach scarp –longshore trough –longshore bars

41. Features of a Beach Dunes – ridges of sediment behind the beach which protect land from waves Sand carried/deposited by wind

42. Features of a Beach Berm – an accumulation of sediment that runs parallel to shore and marks the normal limit of sand deposition by wave action Sand carried/deposited by waves

43. Features of a Beach berm crest – the peaked top of the highest berm; usually the highest point on a beach

44. Features of a Beach Beach scarp – a wall in the base of the berm carved by wave action at high tide

45. Features of a Beach longshore trough – underwater trough (depression) parallel to shore caused by wave action and backwash longshore bars – submerged or exposed accumulations of sand below the low-tide line (nearshore)

46. Features of a Beach

47. Dunes Berms Berm Crest Longshore Trough Longshore Bar Beach Scarp Features of a Beach

48. Dunes Berms Berm Crest Longshore Trough Longshore Bar Beach Scarp Features of a Beach

49. Features of a beach

50. Coasts Primary/Secondary

51. Primary Coasts A primary coast is in almost the same condition as it was when sea level stabilized after the last ice age. Primary coasts form as a result of land processes.

52. Primary coasts: Are often rough and irregular. The ocean has not had time to modify the terrestrial features provided by changes in sea level.

53. Examples of Primary Coasts Deltas (built out by land processes) lava coasts (Volcanic coasts) drowned river valleys fault coasts (Coasts shaped by earth movements)

54. Examples of Primary Coasts – Delta: Nile River; Mississippi River

55. Examples of Primary Coasts – Volcanic Crater Coast: Hanauma Bay, HI

56. Examples of Primary Coasts – Drowned River Valley: Chesapeake Bay

57. Examples of Primary Coasts – Faulted Coasts: Bolinas Bay and Tomales Bay (along western California coast).

58. Secondary Coasts A secondary coast has been significantly changed by wave action since sea level stabilized. Secondary coasts form as a result of marine processes.

59. Processes that shape secondary coasts Waves and currents Stream erosion Abrasion of wind-driven particles Freeze/thaw cycles Slumping water chemistry coral-building marine animals

60. Examples of Secondary Coasts Barrier Islands Cliffed Coasts Reefs/atolls mangrove swamps Sandy beaches salt marshes Erosional coasts

61. Examples of Secondary Coasts – Barrier Islands: Outer Banks

62. Examples of Secondary Coasts – Cliffed Coasts: Maine

63. Examples of Secondary Coasts – Coral Reefs/atolls

64. Examples of Secondary Coasts – Mangroves: Florida

65. Examples of Secondary Coasts – Sandy Beaches: Caribbean

66. Examples of Secondary Coasts – Marshes: East Coast

67. Examples of Secondary Coasts – Erosional Coasts

68. Emergent vs. Submergent Coasts Emergent Coast –the amount of exposed coast is increasing: sea level is lowering. –Due to evaporation, freezing, plate tectonics, etc.

69. Emergent vs. Submergent Coasts Emergent Coast –the amount of exposed coast is increasing: sea level is lowering. –Due to evaporation, freezing, plate tectonics, etc. Submergent Coast –the amount of exposed coast is decreasing: sea level is rising. –Due to precipitation, melting of glacial ice, deforestation, etc.

70. Go back to warmup and label each coast as either primary or secondary

71. Nearshore Offshore Backshore Foreshore Coastal Zones