Witty's Lagoon Sea Bluffs; A Lesson in Erosion EarthCache
Hidden : 3/22/2015
Difficulty:
1.5 out of 5
Terrain:
1.5 out of 5

Size: Size: other (other)

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Geocache Description:


Forword & Warnings

Welcome to Witty’s Lagoon Regonal Park and Beach. To access this Earthcache please park at the provided parking coordinates and walk the trail until you reach Beach Trail, and use this to walk to the beach. Please note that parking is forbidden along Witty’s Beach Rd and at end where the old stairs (now closed to public) were/are, as well as along it’s connecting Still Meadow Rd. Once you are at this very popular beach you will be greeted with breathtaking views. While here one can also see Cruise ships, tankers, and even Navy ships sail past this beach.

Be forewarned that this Earthcache is where the supposed Nude Beach is located.
I have in all my years of coming to this beach in late spring and summer never stumbled upon a nude sunbather at this location. In fact in my teen years I came over here often with my friends not only to get away from the busy beach, but with the hopes of spying a silly nude person. But that never happened, not once, ever!

That being said, you have been warned. That is why this earthcache has been given “Not Appropriate for Children” attribute, so that they don’t witness anything they shouldn’t.

If you are doing this earthcache in the summer months and don't want to risk running into and possibly upsetting nude sunbathers at this location, you can still do this earthcache by checking out the provided additional waypoint at N 48 22.935 W 123 31.010 (105 meters back the way you came). It isn’t as nice of a specimen and is slightly obscured, but you can make the same observations and get the same answers to the questions below.

Nude Warning
Fig1. - Nude sunbathers beyond this point supposedly, though I have never seen any!


Geology of Coastal Bluffs

 Bluffs are widespread landforms and are found all over the world, occurring along approximately 80 percent of the Earth’s coast.

Coastal bluffs are steeply sloping shorelines that are often made up of sediments left behind by massive ice sheets (Glaciers) that covered the area over the last several thousand years. One of the most common glacial deposits found in bluffs is glacial till, which consists of sand, gravel, and clay sediments. This type of composition makes bluffs vulnerable to significant erosion depending on a variety of conditions.

Glacial Till
Fig2. - An example of Glacial Till.


Erosion

 Bluff erosion is caused by a few different factors. As a bluff erodes, the top edge recedes landward, which can cause damage to developed property. The rate at which a coastal bluff erodes depends primarily on the amount and level of wave action the beach receives, the geology of the bluff (what it's made of), and the characteristics of the adjacent beach (like the one you are standing on). Marine-induced bluff erosion is the type most commonly observed, as rising sea levels, tides, and wave action affect the lower slopes. This is a natural process that causes instability, and as the sediment at the base of the bluff erodes away the weight of the mass above it in time causes the hillside to collapse. The occurring landslide then deposits material at the base of the bluff which can act as temporary protection from any further wave damage for a period of time. Eventually, this protection becomes eroded and the whole cycle repeats itself, as shown in this info-graphic below:

Photobucket
Fig3. - Coastal Sea Bluff erosion cycle.


Another factor that contributes to bluff erosion is the steepness, or slope, of the hillside. The steeper the slope, the more likely it is for a landslide to occur. Weather can also contribute to the erosion process. Strong storms like the ones we see here on the BC West Coast can enhance the size and magnitude of waves battering the shore. Rain can saturate the ground and make it less stable. During winter months, the freeze-thaw cycle of a bluff face can have a similar affect. Even human activity can also enhance erosion. For example the simple act walking down the face of a bluff can lead to greater erosion because foot traffic. Clearing trees and vegetation can make the ground less stable and the bluff more vulnerable to erosion. Irrigation channels that lead toward a bluff face can saturate the ground with water, making it more prone to instability.


Stability

 The stability of a bluff can be identified in three different categories:
  • Highly Unstable
    • Near vertical or very steep with little vegetation and lots of exposed, loose sediment. Fallen trees and displaced chunks of sediment are common on the bluff face and at the base.
  • Unstable
    • Steep to gently sloping and mostly covered by vegetation with a few bare spots. Bent and tilting trees may be present.
  • Stable
    • Gentle slope with a continuous cover of grass, shrubs, and other vegetation.
Vegetation/plant growth is an important aspect to the stability of a bluff. Vegetation tends to remove ground water, strengthen the soil with roots, and lessens the impact of rain on the bluff face. Hillsides that are covered in grass, shrubs, or trees are generally more stable than bluff faces that lack vegetation.

The stability of a coastal bluff can also depend on the characteristics of the adjacent beach. In some cases, other natural/unnatural landforms like spits, lagoons and man made breakwaters serve as a barrier that protects the base of the bluff from the ongoing pummel of wave erosion.

___________________________________________________________________________________________________________


Logging Requirements:
Sending Answers by E-Mail via my profile on geocaching.com (Please do not post in your log)
  1. At the posted coordinates, using the info located under "Stability" how would you categorize this bluffs stability (it can be a combo)?
  2. At the posted coordinates, what do you observe that can contribute to the answer to question 1?
  3. Do you think the water and waves still affect the bluffs here?
  4. (Optional) Post in your log a photo of you, your GPS, or your group anywhere along the the beach. Do not include the bluffs in your photos!


Congratulations totemtabou for FTF!





Sources:
  1. http://www.seagrant.umaine.edu/coastal-hazards-guide/bluffs-and-rocky-shores/learn-more
  2. https://fortress.wa.gov/ecy/publications/publications/0406029.pdf
Please note I could not find any local papers on this subject and had to use american sources to develop this earthcache.

Additional Hints (No hints available.)



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