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Bald Head Wave-Sculpted Ripples EarthCache

Difficulty:
2 out of 5
Terrain:
5 out of 5

Size: Size:   other (other)

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Geocache Description:


This Earthcache is accessible via boat, PWC, kayak, or canoe. While the area is beautiful it can be quite dangerous. Always pay attention to wind and weather patterns before heading out and make sure you have all of the appropriate safety equipment with you at all times. There are many private launches along Carter Road and Barcovan Beach Road, however the recommended free parking is located at the end of Alyea Rd - follow the shoe through the channel or leave your kayak on the east side of the island and walk over to the west side to answer the questions.  

Bald Head Island has an interesting history, including being used as a training base for the military in the 1930s and 1940s. It's white sand beaches make it popular with recreational boaters, and geocachers, alike. 

Coastal erosion is the process by which local sea level rise, strong wave action, and coastal flooding wear down or carry away rocks, soils, and/or sands along the coast. Coastal erosion is often defined as the loss or displacement of land along the coastline due to the action of waves, currents, tides, wind-driven water, waterborne ice, or other impacts of storms. Over time, coastal erosion will form ripples in the sand, as a result of the coastal processes at play.

Coastal Process

Abrasion

Abrasion occurs when waves break on land and slowly erode the land, pulling sediment into th water as the waves retreat. As the lake pounds the fragile sand dunes in this area, particles of sand will be pulled into the lake, and if the water is high enough will have the potential to break off sections of the dune.

Sand Depositing

Slower moving waters carry sediments in the direction of water flow. If wave action is high, these deposits will not settle, and will be pulled back into the water. However, when wave action is light (think of a lake that you would want to be paddling on - smooth as glass) the waves will push the sediment onto the beach, and deposit it there. Waves will spread the sediments along the coastline to create a beach, as sand will be deposited in quiet areas along a shoreline.

Waves continually move sand along the shore. Waves also move sand from the beaches on shore to bars of sand offshore as the seasons change. In the summer, waves have lower energy so they bring sand up onto the beach. In the winter, higher energy waves bring the sand back offshore.

When a sandy area is subject to wave action and the wave orbital motion is strong enough to move sand grains, ripples often appear. The ripples induced by wave action are called “wave ripples”; their characteristics being different from those of the ripples generated by steady flows. The most striking difference between wave ripple fields and current ripple fields is the regularity of the former. Indeed, regular long-crested wave ripple fields are often observed on tidal beaches from which the sea has withdrawn at low water

Wave-sculpted ripples form as waves travel across the surface of a body of liquid. These waves cause water beneath the surface to circle around and around, generating oscillating flows that pick up sand grains and set them down in a process that eventually carves out troughs and grooves throughout the sandbed.

Rolling Grain Ripples and Vortex Ripples

Rolling grain ripples appear when the pressure of the wave action is constantly changing, making a "squiggly line" within the sand, rather than straight, vertical lines that always form in the same direction. 

 

Vortex ripples are very rare in nature, because they are formed from constant, reptitive wave action at regular intervals. Frequently only seen within controlled environments where water flow can be controlled, vortex ripples will all appear identical. 

 

In order to log this Earthcache, you must send a message or email (see profile for email) to Pasha88 with answers to the following questions:

1. Have a look at the sand under your feet/boat. Based on the description, do you think that these ripples would be classified as Vortex ripples or rolling grain ripples, and why?

2. Based on your observations, do you feel that man-made structures or human activities have changed the ripples and the effect caused by the waves in this area? Why or why not?

3. Based on the current wave action and the various activities currently being done to preserve the area, do you feel that coastal erosion will be a problem here in the future? Why or why not?

4. Take a photo of your GPSr or yourself/team with a spectacular view in the background at or near the posted coordinates. You may include this photo in your log, or send it with your answers but it must be provided as proof that you visited the area. 
 

This Earthcache was placed by a Proud Platinum Earthcache Master. 

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