This Earthcache is just a bit Northeast of the town of Folly Beach, which is a remarkably well-preserved village with very little commercial development. This results in sustainable natural salt marshes along the coastal wetlands that are along the Folly River, which is opposite from the Atlantic coast side of the Folly Beach island. There is only one location and information sign for specific questions relating to this Earthcache, but salt marshes may be viewed all along the Folly River side of the island. Please plan on responding to each of the three questions and visitors will have the option to upload at least one photo to substantiate their visit.
There is no admission fee for accessing the area of this Earthcache. However, we recommend visiting this area during daylight hours to fully appreciate the natural beauty. Parking for one small/medium sized vehicle is possible between the main road and the cache coordinates.
Part 1: The Marsh
A salt marsh is a coastal wetland that serves as the transition zone between land and tidal salt water. The dominant salt marsh plant in estuaries of the Southeastern United States is Spartina alterniflora, or smooth cordgrass. This amazing plant can tolerate being submerged in tidal salt-water twice each day.
This most common salt marsh plant species provides us with a wealth of benefits. Specifically, Spartina alterniflora provides a habitat for several animals that use the salt marsh as a nesting area, feeding area, and resting area. These animals include the Clapper Rail bird, the Diamondback Terrapin tortoise, blue crabs and fiddler crabs, Periwinkle Snails, Ribbed Mussels, Eastern Oysters, various shrimp, and more!
The rhizomes, or underground stems, of Spartina alterniflora grow into root mats that stabilize the marsh mud and provide erosion control during the incoming and outgoing tidal flows. Spartina stalks break up wave energy during storms, which also lessens potential for erosion damage.
Salt marshes filter pollution from houses and roads that are upstream from the estuaries. These pollutants include pesticides, heavy metals, and excessive nutrients (lawn fertilizers). Marsh sediment and Spartina root systems act as a sponge, burying and absorbing pollutants, which minimizes the toxic effects.
Spartina’s leaf surface excretes salt from glands which allows the plant to survive in salt water. Algae on the leaf surface provides food for grazers, such as the Periwinkle Snail.
Being a perennial plant, Spartina is an excellent indicator of the changing seasons. In the spring, new Spartina plants grow from seeds and rhizomes. In the summer, the marsh takes on a distinct bright green color. During each autumn, white flowers develop along the upper stalk, becoming a seed head. Leaves then turn to a golden-brown color and the seeds are dispersed by the wind. By mid-winter, dead Spartina stalks break off and accumulate as mats of detritus “wrack” on the surface of the mud.
Part 2: The Geologic Substructure
The supporting structure for this area and most of the Southeastern Atlantic coast of the United States is known as "The Pamlico Formation". As measured by well-drilling along the South Carolina coast, thickness of this formation varies from five to fifteen feet. The Pamlico Formation consists of sands, clays, sandy clays, argillaceous sandstone (a relatively pure light-colored quartz-sandstone), and silty clays.
According to glacial control hypotheses, glacial periods featured low sea level and interglacial periods featured high sea level. Pleistocene marine deposits found above sea level south of the Myrtle Beach area indicate there has not been significant movement of this substructure since the last glacial period.
The current conditions of the Pamlico Formation seem of have remained stable since the Sangamonian interglacial age because the only time that sea level could have been higher than at present was during the thermal maximum, approximately 7,000 years ago.
Info sources:
1. Folly Beach Parks and Recreation Development Fund and Folly Beach Salt Marsh Information Sign, Copyright 2015.
2. Southeastern Geology: Volume 4, Number 3, Appalachian State University, February 1963.
Task: Please send responses to the following questions via message or email to the cache owner:
1. Describe how salt marshes control erosion.
2. Describe how Spartina helps keep salt marsh water clean.
3. Describe the most stable material within the Pamlico Formation substructure and how is it more stable compared to the other materials within that substructure.
4. (Optional) Please post a photo of your visit to this Earthcache site.
After visiting this cache and sending responses, please feel free to log this cache as a "found it". We'll review all logs for correct response submissions to verify accuracy.