Team Mollymap Proud Members Of The SCGA
NOTE: This is an earthcache, there is no physical container to find at the coordinates. To get your smiley for the cache, e-mail your answers for the questions below to the cache owner. This earthcache is located on a public beach. Free public parking is available at Seagull Beach.
This is one of our favorite beaches to visit and one day while enjoying the area we noticed these formations on the shore. We learned they were called beach cusps, and this is how they are formed.
Beach cusps are arch pattern shoreline formations. The landward points are called embayments and the seaward points are called horns. Horns are typically made of courser material and the embayments contain finer sediments.
Usually, beach cusps are found on steeper beaches with coarse-grained sediments and regular occurring waves. They most likely happen in a regular pattern with fairly equal spacing between each horn. There are many scientific theories about how beach cusps are formed, but the self organization theory is most widely accepted.
Self Organization Theory
Cusps begin to form due to a slightly lower point on a beach.
When waves hit the shore the water is attracted to the low point and moves up the low point more quickly than the surrounding area. The water at the low point erodes out an embayment or single cusp.
As waves move in and the water hits the sides of the embayment, the water slows down and drops the sediment it is carrying. This drop of sediment creates the horns on each side of the cusp. Eventually the original cusp stops developing and the beach begins to rearrange itself by forming new cusps to the side of the original cusp.
The Cusps nearby begin to develop more rapidly and soon it all becomes evened out.
Now it is time for the questions. To get credit for the cache, please answer the questions below. When answering the questions do your best. It is more important that you learn a new concept about our earth and can apply your knowledge, rather than have a precise answer.
Questions:
1- Give the time and date of your visit and state if the tide is in or out.
2- Find the nearest cusp at the coordinates. What is the distance in feet between the two horns?
3- What is the difference in inches in the elevation between the lowest point of the embayment and the highest point on the horn?
4- Compare the sediment of the horn to the embayment in terms of color and composition.
5- Why do you think cusps form on this particular beach?
Thank you for visiting this earthcache. Please send your answers to the above questions to the cache owner. In your "found it" log feel free to write about your experience, but don't include the earthcache answers. Thanks and we hope you enjoy beautiful Seagull Beach!
Sources:
http://www.marinespecies.org/introduced/wiki/Beach_Cusps
https://en.wikipedia.org/wiki/Beach_cusps
https://www.youtube.com/watch?v=cYFudW-MD9Q