1. Bell Ringer What is one way humans are hurting the oceans?
How do you feel now after watching the documentary?
Test TOMORROW! Study!

2. The Shore

3. Continental Margins
Continental margin -- part of the continental crust that is actually below sea level
Three parts of continental margins:
Continental shelf
Continental slope
Continental rise

4. Continental Margins
Continental shelf – The shallowest part of the continental margin, extending from the shore out to the sea

5. Continental Margins
The continental shelf marks the boundaries between territorial (belonging to a country) waters and international waters.

6. Continental Margins
Continental slopes -- sloping regions beyond the continental shelves where the seafloor drops away quickly
Considered the true edge of the continental crust

7. Continental Margins
Continental rise – deposited sediment that collects at the bottom of the continental slope

8. The Shore Shore – where the ocean meets the land
Shaped by waves, tides, and currents both eroding and depositing sediment

9. The Shore
Beaches – bands of sediment deposited and moved around by waves at the shore
Sediment size depends on the energy of the waves striking the coast

10. The Shore The type of sediment depends on source material
Example: Hawaii has black sand beaches from black volcanic rocks

11. The Shore
Southern Florida/Bahamas – white/pink sand from corals and seashells

12. Shore Landforms
Rocky headlands – points of land sticking out in the ocean caused by the destructive action of breaking waves and the resistance of rocks to erosion

13. Shore Landforms
Sea stacks/sea arches – form from wave erosion at the rocky headlands

14. Shore Landforms
Tombolo – sand that forms between, and later connects, the mainland and an island
The island then becomes the tip of a peninsula
Sha Chau Tombolo
near Hong Kong

15. Shore Landforms
Barrier Islands – Long ridges of sediment separate from mainland
Can be several km wide, but are unstable and temporary
Example: NC Outer Banks

16. The Outer Banks
Highway 12 – highway that travels the length of the Outer Banks

17. What happens when you build a road on an unstable, temporary barrier island?

18. Shoreline Currents Longshore bar – underwater sandbar in the surf zone
Longshore current – current that flows parallel to the shore
That feeling of being pulled to the side when you’re in the water

19. Shoreline Currents
Rip Currents – currents that flow out to sea through gaps in the longshore bar
Can reach speeds of several km/hr

20. Shoreline Currents
If caught in a rip current, you should swim parallel to the shore to get out of the current, rather than trying to swim against it
Remember landslide mitigation?

21. Protective Structures
Wouldn’t it be awesome to have a house right on the beach?
…or would it?

22. Protective Structures
Protective structures -- man-made structures are built to prevent beach erosion and destruction of oceanfront properties
However, they interfere with natural shoreline processes

23. Natural Shoreline Processes
Storms create strong waves that remove beach sand and deposit it in large sandbars offshore.
Weeks and months later, the sand is returned to the beach by calm-weather waves

24. Natural Shoreline Processes
Natural processes can take too long to protect beach homes, so protective structures are built

25. Protective Structures
Seawalls – built along shore to protect beachfront properties
Effects – Reflect waves back to the ocean, worsens beach erosion
Seawalls in Japan (left) and Galvaston, TX (top)

26. Protective Structures

27. Protective Structures
Groins – walls built in the water to trap beach sand
Effects – traps sand from longshore currents but deprives other nearby beaches of sand

28. Protective Structures
Jetties – concrete walls built to protect a harbor entrance from drifting sand
Effects – trap sand up the shore, prevent sand from reaching beaches down the shore

29. Protective Structures
Beach Nourishment – the process of dredging (removing) sand from another location and dumping it onto an eroding shoreline to widen the existing beach

30. Nags Head, NC

31. Protective Structures
This doesn’t stop erosion from happening, it just counteracts the process
This means that it must be repeated on a regular basis
Expensive
Example: Nags Head’s beach nourishment budget is $36 million
Because sand is being dredged from another location (usually off the continental shelf), it can harm ocean habitats and organisms

32. Study Guide Take out all of your notes from unit 6
Complete the study guide
If you have head phones, feel free to listen to music