By Domonique deBeaubien, THPO Collections Manager
If you’re a regular reader of our blog, you may remember a special story titled “Lost in the Swamp: the Search for Fort Shackelford,” where Tribal Historic Preservation Office (THPO) Archaeologist, Shawn Keyte, recounted the harrowing challenges of locating a U.S. Army fort burned to the ground in 1855 by the Seminoles living on Big Cypress.
This winter, THPO Archaeologists Shawn Keyte and Dave Scheidecker continued their search to locate the lost fort. Shawn and Dave, along with the rest of the Tribal Archaeology crew, were committed to finding the long lost fort. After a long and fruitless field season of metal detection, former THPO Research Coordinator Rechanda Lee commented that the only place they hadn’t looked yet was under the truck. So that’s exactly what they did!
Surprisingly, this unusual methodology led to an exciting discovery: square cut nails from the 1800s! THPO Archaeologists were so encouraged by this find that they put in several new test units to further explore what may be hidden under the surface.
A test unit is a small square shaped area where archaeologists excavate down carefully, layer by layer, until they hit bedrock. This helps them see changes in the soil, and accurately document any artifacts that they may find. This new test unit yielded a very exciting discovery: a burned piece of wood! This may not seem like much, but many 19th century forts were constructed entirely of wood. While we had located a few metal nails and objects that may have dated to the correct time period, what our archaeologists really wanted to find was evidence of the structure itself. As the crew continued their work, they began to see a series of dark oval stains in the soil, each about the size of a post. As they continued to excavate, they realized that remnants of the posts were actually still preserved! According to Archaeologist Shawn Keyte, this post may have formed part of the stockade (or fence) surrounding the wooden blockhouse. Officers would have kept quarters in the more robust blockhouse, while soldiers would have erected tents within the confines of the stockade.
As exciting as this discovery was, the team wanted to ensure that the artifacts were removed from the ground safely. Robin Croskery Howard, Ah-Tah-Thi-Ki Conservator, was called out to the site to help extract some of the wood for lab testing and preservation. Finding preserved wood in the Everglades is a rare occurrence. As wood ages in a moist and acidic environment, it often loses its structural integrity and rapidly decomposes. Our team wanted to be extra sure their find didn’t crumble to pieces after exposure to the air! Shawn, Dave, and Robin worked carefully to extract the wood, as well as collect a sample of the dark soil surrounding each of the posts.
Once back in the THPO Lab, the Collections team set to work. To get the most precise results possible, we often use radiocarbon dating. In these instances we send out organic material, like animal bone or charcoal, and measure the amount of Carbon-14 left in the sample. When a piece of wood is burned, the Carbon-14 in the object begins to slowly break down at a consistent rate. Scientists are able to measure the amount of Carbon-14 present, and compare it to closely calibrated charts and determine a very precise age. If you look carefully at the soil in the test unit, it’s very dark compared to the light colored soils found nearby. Such an intense darkening of the soil was caused by a large quantity of ash and charcoal produced by a fire. The soil sample was packaged up and sent off to a lab in hope that they could extract enough charcoal in the soil to perform C-14 testing to determine when the fire occurred.
In addition to the soil, we also sent out a large piece from one of the wooden posts. The lab will first use a high powered microscope to determine what type of tree the post was made from, and then use a small segment of the wood sample for C-14 dating!
We haven’t received all of the results yet, but some are in! The charcoal in the soil sample dated to 1840 +/- 30 years. This is exactly the date range we were hoping for! This places our charcoal right around the time Fort Shackelford was destroyed, 1855. While we anxiously await the results of our second C-14 date, we are left to wonder, did we find Fort Shackelford? The Tribal Archaeology Section heads back out this April to continue the search. Check back soon to find out more!