1. Shorelines
Bob Leighty
GLG Physical Geology

2. These notes and web links are your primary “lecture” content in this class. Additionally, various articles are assigned each week to supplement this “lecture” information. I believe you’ll have enough information to reference without having to purchase a costly textbook.
These lecture notes are very similar to the ones I use in my traditional classes. You’ll find they are loaded with imagery and streamlined text that highlight the most essential terms and concepts. The notes provide a framework for learning and, by themselves, are not meant to be a comprehensive source of information.
To take advantage of the global knowledge base known as the Internet, I have included numerous hyperlinks to external web sites (like the Wikipedia, USGS, NASA, etc.). Follow the links and scan them for relevant info. The information from linked web sites is meant to supplement and reinforce the lecture notes – you won’t be responsible for knowing everything contained in them.
As a distance learning student, you need to explore and understand the content more independently than in a traditional class. As always, I will help guide you through this learning adventure. Remember, Dr. Bob if you have any questions about today’s lecture
Leave no questions behind!
Explore and have fun!

3. Shorelines
Why Do We Care?
WWW
Lots of people live at/near the shore

4. Shorelines
Why Do We Care?
Nature vs. people

5. Shorelines
Why Do We Care?
Nice scenery - recreation

6. Shorelines
Why Do We Care?
Did other planets have oceans too?

7. Shorelines
All About Waves
A wave (water, sound, light, etc.) is not a physical object – it is a moving pattern of up & down motion

8. All About Waves Wavelength (meters) - Distance between wave crests
Shorelines
All About Waves
Wavelength (meters) - Distance between wave crests
Amplitude (meters) – Height of crest from an undisturbed state
Frequency (1/sec) – # of wave crests passing any point per sec
wavelength () = velocity / frequency

9. All About Waves As ocean waves approach the shore ...
Shorelines
All About Waves
As ocean waves approach the shore ...
... water depth decreases, wave speed decreases, wave height increases, & ...

10. Shorelines
All About Waves
... and then the wave starts to break!

11. This 1946 breaking tsunami wave is over 6 meters high!
Shorelines
All About Waves
This 1946 breaking tsunami wave is over 6 meters high!

12. … and then bend toward the shoreline
Shorelines
Nearshore Currents
Waves slow as they reach shallow water …
… and then bend toward the shoreline

13. Shorelines
Nearshore Currents
Longshore currents - Net current movement down the beach
Longshore drift – Sediment movement parallel to shore

14. Nearshore Currents Rip current - Carries water back out to sea
Shorelines
Rip current - Carries water back out to sea
Surfer-dudes use them

15. Types of Shorelines Erosional Wave refraction erodes headlands
Occur as land is uplifted or sea level drops
Common at active continental margins (West Coast, USA; glaciated areas also)

16. Types of Shorelines Erosional
Headlands eroded into sea cliffs, stacks, arches, wave-cut platforms, etc.

17. Types of Shorelines Depositional Sediment deposited by currents
Occur as land sinks or sea level rises
Common at passive continental margins (East Coast,USA)

18. Types of Shorelines Depositional
Spits, hooks, baymouth bars, barrier islands
Drowned rivers (estuaries)

19. Shorelines
Shoreline Problems
Developing beach areas can easily change beach dynamics
Erosion problems are typically hard & expensive to fix

20. Shorelines
Shoreline Problems
Ballast (boulders) & sea walls - stop erosion, but no beach left
Beach nourishment – sand pumped onshore, but expensive

21. Shorelines
Shoreline Problems
Jetties - trap sediment on one side, but cause erosion on the other

22. Shorelines
Shoreline Problems
Groins - trap sediment on one side, but cause erosion on the other

23. Shorelines
Shoreline Problems
Breakwaters – Shield beach from waves, but sediment accumulates behind
Tombolos – Natural breakwaters

24. Shoreline Problems Bottom-line solution: move somewhere else!
Shorelines
Bottom-line solution: move somewhere else!
In 2000, the Cape Hatteras lighthouse was from its original location at the edge of the ocean to safer ground 2870 feet inland.

25. WWW Links in this Lecture
Shorelines
> Beach -
> Wave -
> Wavelength -
> Frequency -
> Ocean wave -
> Longshore drift -
> Rip current -
> Headlands - > Sea stack - > Arch - > Wave-cut platform - > Spit - > Baymouth bar - > Barrier island - > Estuary - > Beach nourishment - > Jetty –
> Breakwater - > Tombolo -