Coquina: St. Augustine’s Stepping Stone

452 year ago St. Augustine appeared as a fixed point upon European maps, and an unlikely hero should take the lion’s share of credit for that distinction: a tiny clam. The Donax (specifically Donax variabilis) stood up to the cannons and muskets of British invaders and provided shelter to our colonial forebears despite the ravages of fire and rot. Of course, by the time the Donax were providing this service they had been dead for a very long time. You may be more familiar with them as “coquinas”, which fossilize and form coquina stone. The coquina stone in St. Augustine comes from what is known as the Anastasia Formation, which stretches from the St. Augustine Inlet south to Palm Beach, and as far west as 30 miles in some parts. It was formed during the Pleistocene Epoch (from 2 million-12,000 years ago – yes, I know that covers a lot of time). It formed in layers with a sand-shell-clay mixture between the coquina shells. The coquina stone is saturated with water when it is first quarried and has to dry out, or “cure”, before it can be used structurally. Stone used in the construction of the Castillo de San Marcos had to dry a year before it was used.

Construction didn’t start on the Castillo de San Marcos until 1672, but in a 1583 letter Governor Pedro Menéndez Marquez wrote to the King, “about three years hence I went to an Indian town four leagues from this…[place]…when I found an abundance of stone, near the sea…I will endeavor to have some of it brought here….” He “found” the coquina stone in the same sense that the Europeans “found” the Americas, the indigenous population of course knew about the stone but did not have the tools available to quarry it in quantities suitable for construction. For that matter, neither did the Spanish for a number of years. They lacked the equipment, skilled laborers, stonecutters, engineers, and tools (i.e. money) to make use of it.

The surface of the stone is porous and susceptible to mold and moss growth, so in colonial times a coquina surface was always covered with stucco and a coat of whitewash. These days many people leave coquina stone exposed because it looks rustic and romantic. Unfortunately, this is not only historically inauthentic but it puts the stone itself at risk. All the coquina stone used in historic buildings in St. Augustine came from quarries on Anastasia Island, the earliest of which were near the present day entrance of Anastasia State Park, and can still be visited today! So remember, the next time you go for a walk on the beautiful beaches of St. Augustine, say “thank-you” to the little coquinas you see, because we might not be here today without them.

All the images in this blog post are from a slide show presentation on file at the Governor’s House Library.