The pure coquina outcroppings at Washington Oaks Gardens State Park close to Palm Coast, Florida, are among the many largest on the Atlantic Coast. Credit score: Washington Oaks Gardens State Park
Almost each little one who’s performed on the seashore has constructed a easy sand citadel by making a turret
with an upturned bucket of sand. Others, extra elaborate (and sometimes constructed with assist from an
bold mum or dad), boast a number of constructions surrounded by moats and rivers that ebb and move
with the movement of ocean waves.
However do you know that close to St. Augustine, Florida — the nation’s oldest metropolis — there exists an
precise “citadel” fabricated from sand? Situated on 20.5 acres on the western shore of Matanzas Bay, the
Castillo de San Marcos Nationwide Monument is the oldest (circa 1695) and largest masonry fort in
the continental United States.
The Castillo’s masonry, or stonework, is essentially comprised of coquina (Spanish for “small
shells”) — a pure concrete derived from the ocean. Coquina is a uncommon type of limestone
composed of the shell fragments of historic mollusks and different marine invertebrates, which, over
time, are glued collectively by dissolved calcium carbonate within the shells. Coquina can also be the identify of
a typical tiny clam discovered in every single place on Florida seashores. Their shells, which are available
numerous colours, are mirrored within the Castillo’s muted hues.
As a constructing materials, coquina is light-weight, straightforward to seek out (it’s indigenous to the Florida coast),
straightforward to make use of, and almost indestructible. Not solely is coquina bullet-proof, it’s just about cannon-ball-
proof! Attributable to its plentiful microscopic air pockets, coquina is well compressed. In days gone, cannon
balls fired on the Castillo merely lodged in its partitions. Which, one supposes, is why the previous fort nonetheless
stands after 300 years.
Probably the greatest locations to see coquina in its pure state is Washington Oaks Backyard State Park
close to Palm Coast, Florida, about 30 miles south of St. Augustine. The park’s picturesque coquina
outcroppings are a number of the largest on the Atlantic Coast.
A associated constructing materials is tabby, usually referred to as coastal concrete, which is mainly artifical
coquina. Tabby consists of the lime from burned oyster shells combined with sand, water, ash,
and different shells. Way back to the 1600s, Spanish and English settlers used tabby to construct their
properties and different constructions, and to pave their roads, all through the coastal Carolinas, Georgia,
Many tabby buildings nonetheless stand right now, together with Georgia’s Fort Pulaski close to Savannah and the
R.J. Reynolds mansion on Sapelo Island. These historic constructions, amongst many others, are
testomony to each the ingenuity of early People and the untold bounty of the ocean.