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The Ancient Architecture of Edisto Island, South Carolina

How does one re-create the original appearance of surrealistic architecture that at least dates to 2110 BC?   The structures of Fig Island National Historic Landmark were constructed of oyster and clam shells, mixed with sandy soil and the “sweepings” of plazas, i.e. garbage.   In the 4000+ years since their creation many of the shells have decomposed, a legion of hurricanes have passed over the island and anonymous intruders have “mined the shells.”

This article is a companion to “Edisto Island, South Carolina . . . 4000 Years Ago” – published on December 24, 2015.  The December 24th article should be read first.

Site Plans of Fig Island National Historic Landmark

Site Plan based on drawing in "Archaic Shell Rings" by Michael Russo and Rebecca Saunders

Site Plan based on a drawing in “Archaic Shell Rings” by Michael Russo and Rebecca Saunders. (2003)


Three dimensional, virtual reality site plan by Richard L. Thornton, Architect (2015).

Changes by Mother Earth

All earthen and shell structures erode and subside over time.  When I was preparing plans for the re-construction of earthen Civil War fortifications several years ago,  the redans, parapets and breastworks that were 8 to 12 feet high in 1864, were 1 to 3 feet high a century and a half later.  This was due to both gravity, the erosive effect of heavy rainstorms and disintegrating effect of freeze-thaw cycles.   In a thousand years, freezing and thawing have turned Welsh and English castles into piles of stone.

Soil and clay also compact over time, due to gravity.    Irregardless of the effects of erosion, most of the clay and soil Native American mounds built 1200 to 600 years ago have subsided at least 10-20% of their original height.   The taller a mound, the greater the amount of subsidence.  Mounds that were built in a short period of time would have experienced larger percentages of shrinkage.

The sea shells in the Edisto Island structures stabilized the structures when initially built, but most have chemically decomposed due to the instability of calcium carbonate in the shells. The structures would have shrunk as the shells decomposed.

In calculating the original height of the Fig Island structures,  I assumed a 33% vertical reduction.  This is probably conservative, but there is no way to know what effects decomposition, hurricanes, wind and “shell miners” have had on their forms.

Shell miners, artifact hunters and archaeologists

It is known that European colonists, coastal planters and contractors mined the shell rings on the South Atlantic Coast to obtain shells for making hydrated lime and tabby, pave roads and fill gullies.   The C-shaped Ring B above probably lost most of its ring to miners.  However, this is not known for certain, so I showed the inner circle of Ring B, but did not include the remainder of a full ring in the computer model.

It is also known that artifact hunters have dug into many of the shell rings on the South Atlantic Coast.   The rings do not contain many “trophy artifacts” so this is not as much a problem as with earthen burial mounds.  Nevertheless,  artifact hunters could have altered the architectural forms somewhat.

We learned from former College of Charleston professor, Gene Waddell, that Ring Two was originally continuous.  In 1971 and 1972, South Carolina Institute of Archaeology and Anthropology archaeologist,  E. Thomas Hemming,  excavated a ditch through Shell Ring Two and did not replace the contents afterward.  National Park Service archaeologists did not know this and so showed the ring as naturally having a gap in it.

Wooden buildings on shell structures

Read the literature on shell rings in recent decades and you will be told that they didn’t have houses or temples on them.  The reason given is that “no post holes have been found.”    Actually, the absence of post holes doe not mean diddlysquat.

The vast majority of Native American structures on the South Atlantic Coast were constructed of saplings, woven together like baskets.  They have left few, if any footprints.

There are no stones in the South Atlantic Coastal Plain suitable for making axes and wedges, strong enough to cut down trees.  It was far easier to break saplings and weave them together.   Stouter buildings were not constructed until greenstone from the Georgia Mountains became generally available through trade.  Even then,  the structures in the seasonal fishing and hunting camps were woven from samplings.


The huts in coastal fishing camps on the South Atlantic Coast were probably identical to the houses of people living on Edisto Island 4,000 years ago.

I found one location on Shell Ring Complex 1 that showed evidence of wooden buildings.   There were two rectangular shell platforms on the southern promontory that would have supported 15′ x 24′ and 15′ x 28′ buildings, respectively.   The buildings probably consisted of vertical posts with a split-cane lattice in between.


The prominent location of the two buildings, overlooking the deepest shell ring, suggests that they were either temples or elite housing. There may have been other wooden structures on the Fig Island shell structures, but with the limited archaeological information  available, it is impossible to describe them.



Architectural forms and elements

Fig Island National Historic Landmark is far more sophisticated and complex than any of the other known shell ring sites on the South Atlantic Coast.  It contains architectural elements that one does not see again until the Fort Center Earthworks began developing near Lake Okeechobee, Florida around 450 BC.   In fact, the half moon and oval mound, along with massive C-shaped mound seen at Fig Island are frequent elements seen in all the town sites around Lake Okeechobee between 300 BC and 1150 AD.  There may be a cultural connection.

The earthworks of Fort Center, Florida superimposed onto a NASA satellite image.

The earthworks of Fort Center, Florida superimposed onto a NASA satellite image.

Shell Ring Complex 1 contains many architectural elements that seem to have begun as one or more simple shell rings.  These elements include rings, craters, oval shaped mounds,  cone shaped mounds,  a half moon shaped mound,  terraces and most uniquely, curved ramps leading to the summit.   Note that the largest ramps base aligns as a precise tangent with the walkway connection to Shell Ring 2.   Such details are very rare in the architecture of even the most advanced civilizations in the Americas.

Shell Ring 2 is a hexagon.  Earthworks like this one can be found in area of the Upper Amazon Basin, where the oldest pottery in the Americas has been found.  This similarity suggests a cultural connection between Edisto Island and the earliest advanced cultures in the Amazon Basin.  At least three of the points of the hexagon had ramps leading up to the top.

Shell Ring 3 is particularly an enigma.   The Y-shape is not seen anywhere else on the South Atlantic Coast.  It seems to be an abstract symbol or a glyph, but may in fact had a practical function or meaning . . . perhaps a constellation?

The Fig Island Shell Ring National Historic Landmark has many obvious astronomical functions relating to the solar azimuth.  However,  its extremely complex architectural details suggest that the shrine was used to monitor other heavenly bodies such as the Moon, planets, comets and stellar constellations.  Use of planetarium software will be utilized in the future to determine where the moon, planets, stars and comets were located in the sky when the structures were being built.

This is a screen shot of the finished CADD model that was developed from a topographic map.

This is a screen shot of the finished CADD model that was developed from a topographic map.

Creation of the computer model

Normally,  CADD models begin with digital survey data that is furnished to the architect by the surveyor or civil engineer. In this situation, I had to manually trace the contour lines on a topographic map published in a National Park Service report with CADD and then convert them to “true scale” x, y and z coordinates.  The next step was creating triangular and rectangular “3D faces” that converted the complex intersecting curves into three dimensional surfaces.  Polar geometry, fractal geometry and integral calculus were utilized to make the calculations.

The final step is loading the 3D CADD wire frame model into virtual reality software and designating the 3D faces with appropriate building materials.   I use Artlantis virtual reality software from France,  because it includes hundreds of historic and prehistoric building materials, which are completely unavailable in software manufactured in the United States.   Individual views of the model include about 24 different variables including the date, time of day, latitude & longitude, weather conditions, camera location, lens width, focal length, etc.  The results can be astonishing.

Below are some other views of the Fig Island archaeological site as it appeared when all the structures were completed:




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Richard Thornton is a professional architect, city planner, author and museum exhibit designer-builder. He is today considered one of the nation’s leading experts on the Southeastern Indians. However, that was not always the case. While at Georgia Tech Richard was the first winner of the Barrett Fellowship, which enabled him to study Mesoamerican architecture and culture in Mexico under the auspices of the Institutio Nacional de Antropoligia e Historia. Dr. Roman Piňa-Chan, the famous archaeologist and director of the Museo Nacional de Antropologia, was his fellowship coordinator. For decades afterward, he lectured at universities and professional societies around the Southeast on Mesoamerican architecture, while knowing very little about his own Creek heritage. Then he was hired to carry out projects for the Muscogee-Creek Nation in Oklahoma. The rest is history. Richard is the Tribal Historic Preservation Officer for the KVWETV (Coweta) Creek Tribe and a member of the Perdido Bay Creek Tribe. In 2009 he was the architect for Oklahoma’s Trail of Tears Memorial at Council Oak Park in Tulsa. He is the president of the Apalache Foundation, which is sponsoring research into the advanced indigenous societies of the Lower Southeast.



    Hi Richard,

    I hope you get this email since you have changed web hosts when this article was published.

    The image links are broken. Your writings are most enjoyable and thought provoking, but images you created with some very complex software (I’ve worked in CADD and GIS) greatly enhance the articles. Thus, I hope the links in your series about Fig Island could be fixed or available in newer articles.

    Thank you so much for your great efforts and mind-expanding articles!

    Kindest regards,
    Bill in Roswell, GA

    • I don’t know who the web host is. Our long time web host disappeared from the scene. suddenly we had many more ads and the new web host refused to communicate with us.


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