How does sand kind?

giant bumphead parrotfish

The enormous bumphead parrotfish is an incredible fish that may stay to be 40 years outdated, rising as much as 4 ft lengthy and 100 kilos. They use their massive head bumps to actually bump heads throughout aggressive shows, when massive numbers of fish mixture to spawn on a lunar cycle. The bumphead parrotfish excretes white sand, which it could produce on the price of a number of hundred kilos a 12 months!


The environmentalist Rachel Carson wrote, “In each curving seashore, in each grain of sand, there’s a story of the Earth.”

Sand comes from many areas, sources, and environments. Sand varieties when rocks break down from weathering and eroding over 1000’s and even thousands and thousands of years. Rocks take time to decompose, particularly quartz (silica) and feldspar.

Typically beginning 1000’s of miles from the ocean, rocks slowly journey down rivers and streams, continuously breaking down alongside the best way. As soon as they make it to the ocean, they additional erode from the fixed motion of waves and tides.

The tan shade of most sand seashores is the results of iron oxide, which tints quartz a lightweight brown, and feldspar, which is brown to tan in its unique kind. Black sand comes from eroded volcanic materials reminiscent of lava, basalt rocks, and different dark-colored rocks and minerals, and is usually discovered on seashores close to volcanic exercise. Black-sand seashores are frequent in Hawaii, the Canary Islands, and the Aleutians.

The by-products of dwelling issues additionally play an vital half in creating sandy seashores. Bermuda’s preponderance of pleasantly pink seashores outcomes from the perpetual decay of single-celled, shelled organisms referred to as foraminifera.

Much less frequent however no much less inviting seashores, devoid of quartz as a supply of sand, depend on a wholly totally different ecologic course of. The well-known white-sand seashores of Hawaii, for instance, truly come from the poop of parrotfish. The fish chew and scrape algae off of rocks and useless corals with their parrot-like beaks, grind up the inedible calcium-carbonate reef materials (made principally of coral skeletons) of their guts, after which excrete it as sand. On the identical time that it helps to take care of a various coral-reef ecosystem, parrotfish can produce a whole bunch of kilos of white sand every year!

So the subsequent time you unfurl your seashore towel down by the shore, ponder the sand beneath you, which, as Rachel Carson mentioned, is telling you a narrative concerning the Earth. It’s possible you’ll be about to comfortably nestle down within the stays of million-year-old rocks. Then once more, chances are you’ll quickly come to relaxation upon an limitless heap of parrotfish poop.

What are coquina and tabby?

The Castillo de San Marcos National Monument in St. Augustine, Florida, stands sentinel over Matanzas Bay. The coquina structure remains sturdy after three centuries. (Photo credit: iStock Getty Images)

The Castillo de San Marcos Nationwide Monument in St. Augustine, Florida, stands sentinel over Matanzas Bay. The coquina construction stays sturdy after three centuries.

Gazebo and oak tree at Washington Oaks Gardens State Park. Photo courtesy Washington Oaks Gardens State Park

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,
and Florida.

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.