Coquina in Spanish Colonial Florida

By VISIT FLORIDA staff
Published September 19, 2011

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Florida's Spanish Colonial Heritage Trail

How the Spanish used native materials to make stronger settlements – and where you can find the remnants today.

The Spanish soldiers in St. Augustine built their fort and homes out of the pine trees and palmetto so plentiful in the area, but their wooden settlement was destroyed more than once by storms or burned by pirates and other European raiders. On nearby Anastasia Island, the Spaniards discovered a better building material – deposits of coquina, a rock made of broken shells. The word coquina means “tiny shell” in Spanish.  

Coquina forms a sedimentary structure underlying much of the Atlantic shore of Florida from clam shells accumulated when the area was underwater. Later the sea level dropped and rain dissolved calcium carbonate from the shells, cementing the quartz and shells together into coquina rock.

The Castillo de San Marcos was never captured in battle, thanks at least in part to the coquina.

The people of St. Augustine learned they had happened upon an amazing defensive material. As the soft stone was exposed to air, it hardened. The Spanish learned to waterproof the coquina stone walls by coating them with plaster and paint, so the coarse rock structures you see today, such as the Castillo de San Marcos, would have looked more refined. However, when besieging ships bombarded the Castillo, the walls simply absorbed the cannon balls. The Castillo de San Marcos was never captured in battle, thanks at least in part to the coquina.

At first, hand tools were used to cut out blocks of the soft shellstone which were then pried loose along natural layers in the rock. The blocks were loaded onto ox-drawn carts, then barged across Matanzas Bay to St. Augustine. The blocks were used to construct the Castillo de San Marcos and many other public and private buildings. Finally, in 1671, the Spanish embarked on large-scale quarrying on Anastasia Island. At this time, the island was called Cantera, Spanish for quarry.

In Anastasia State Park, located at 1340 A1A South, you may take a short walk down a shaded and signed trail to view the site of these labors. This site is one of several on the island; the St. Augustine Amphitheater is located in another site.