Discover the lost Spanish fortress on the island of Florida

Laser and radar technology helped scientists discover a 454-year-old relic of a Spanish fortress on an island off the Gulf of Florida.

The fruits of technology 

The fortress , Fort San Antón de Carlos , is home to one of the first Jesuit missionaries in North America. The Spaniards built it in 1,566 in the capital of a mighty Native American kingdom controlled by the Calusa. Today, the site is known as the Mound Key , an island in Estero Bay.

Historical documents of Spain say that the capital of Calusa and the fortress of San Antón de Carlos (named after the Catholic patron saint of lost things) lie on the Mound Key. But it wasn't until archaeologists using a laser technology called lidar (light and range detection) and cross-ground radar to locate the fort.

The map indicates the location of the Mound Key on the Florida Gulf Coast.

'Before the work, the only information we got from Spanish documents, which suggested that the capital of Calusa is located on Mound Key and Fort San Antón de Carlos is also there' , William Marquest, director a candidate for South Florida archeology and ethnography speaking at the Florida Museum of Natural History . 'Archaeologists and historians have visited the site and collected pottery from the surface, but until we found physical evidence of King Calusa's house and the fortress, we couldn't completely. sure'.

Lidar is essential for this project, as it helps to map laser locations, giving archaeologists a detailed view of the geography and structure of the site. Similarly, cross-ground radar shows the exact position of the buried structures. This radar technique works when an operator pushes the device to look like a lawn mower on a location and the device will shoot FM radio waves to the ground. When these waves hit structures - in this case the fortress relics - the waves bounce off, allowing researchers to map any underground features. When the team excavated the site, they found the fortress remains as well as ceramic debris and beads.

Many secrets need to be discovered

The fortress was found to be the oldest example of 'tabby' architecture in North America, meaning its walls were made from concrete shells. The researchers said the material was created when lime from burnt shells was mixed with sand, ash, water and broken shells. The Spaniards used the original tabby architecture at Mound Key, using it as mortar to stabilize the columns in the walls of their wooden structures, the researchers said. The British then used tabby in colonies on American soil, including southern plantations.

However, more tabby structures will be found, because archaeologists have only discovered part of the fortress. 'Seeing the fortress's straight walls rise just a few inches from the ground, is quite interesting for us. This is not only a confirmation of the location of the fortress, but it also promises that Mound Key will shed light on a history of Florida as well as the United States with little known '' - Mr. William Marquest said .

In 2018, archaeologists published other findings from this site in the Anthropological Journal of King Calusa's castle, also on Mound Key. Calusa is a complex cultural culture of hunters - gatherers - fishermen against European colonists for nearly 200 years. The Calusa used shells in almost everything, including tools, utensils, jewelry, and even in the construction of huge 'lakes' , keeping fish in underwater fins so they could Easily caught to feed the growing population.

Despite being the most powerful society in South Florida, Calusa is still drawn into Spain's wider world economic system. However, by being honest with their values ​​and way of life, Calusa shows resilience that is unmatched by most other indigenous societies in the Southeastern United States.