On a recent trip to survey the beaches of Anguilla, I stopped to admire the handiwork of two young girls industriously digging and piling sand. They were sisters, they told me, five and three years old, and asked if I wanted to help. Having enjoyed many long-ago summer days covered in so much sand that I looked like a sugared donut, I knelt right down and got to work. After several minutes, we had a good mound and, under their expert direction, I began to shape it into a circular, flat-topped structure. “It’s going to be a great first floor for our sand castle,” I said.
They both stopped and looked to see if I was serious. “This is not a castle,” said the older girl, a simple fact testified to by her sister’s serious head-shaking. I studied our creation for a few moments, feeling their stares and their hopes that I wasn’t so silly that I didn’t know what I’d helped build. Finally I gave up, “It’s not?”
“No!” they said in unison. “It’s a strawberry cake.”
Castles, pyramids, people: You can make anything out of sand — even strawberry cakes. But what is sand actually made of?
“Itty-bitty rocks” is a common answer, though for the Caribbean, that’s only a tiny bit correct. Once you know the complete story of our sand, you’ll never plop down on the beach again without appreciating the finer things.
Caribbean sand comes in every shade, from white to black, pink to gray and every nuance of beige. Pure white is the most coveted color, although “pure” is a dubious adjective for a collection of dead algae, animal skeletons and even fish poo — the main
components of the finest Caribbean beaches. The whitest — as well as the softest — element is an alga of the genus Halimeda, which grows in bright-green flaky clusters on reefs and seagrass beds. When they die, the halimeda flakes blanch and fall to the seafloor. Currents carry them to lucky beaches where they bleach to a dazzling snow-white.
Look very closely at any of the Caribbean’s best beaches and you’ll see what appears to be a marine-life mass-murder scene: the remains of pepper-grain size sea biscuits, fragments of brittle sea urchin shells, snails and clams so small they’re called micromolluscs, crushed bits of coral, the bodies of single-celled critters called foraminifera (forams) and star-shaped spicules from shredded sponges. The boneyard effect, though, has its benefits: White sand not only looks the cleanest, it is in fact the cleanest because sand derived from animal shells (calcium carbonate) releases alkaloids that hamper the growth of bacteria and algae.
Coral contributes a relatively small amount of material to the beach, though the way it’s converted from rocky reef to cushy sand is noteworthy. Every diver and snorkeler has heard the unsettling sound of a parrotfish scraping the reef with its fused front teeth. Once it has a mouthful, the beaky fish uses crushers in its throat to pulverize the limestone so it can digest the chewy coral animal. The rest? Let’s just say that the extra-fine stuff you’re running through your fingers once ran through a parrotfish.
Black-sand beaches — which seem exotically romantic until you walk across one on a sunny Caribbean day and melt the soles of your feet — are produced by volcanoes. Upon hitting cool seawater, molten lava shatters into grains of black glass that wash ashore on volcanic islands like St. Lucia, St. Vincent and Dominica.
Beachgoers are often most fascinated by blushing beaches, such as those on Bermuda and Harbour Island. Thank the forams for the pink hue. Some 4,000 species of these primitive life forms fill the oceans, and a few grow red shells that, when washed ashore, mix with the white sands to form the famous pink beaches.
Near the end of my Anguilla trip, on another beach, I scooped up a handful of sand, thinking maybe I’d build my own sand castle. Amidst the tiny bits of shell in my palm sat several large, intact red forams. They looked just like strawberries.
Caribbean Travel & Life is the magazine for anyone in search of the perfect tropical getaway. Each issue presents expert insider’s advice on where to find the Caribbean’s best beaches and attractions, its finest resorts and spas, liveliest beach bars and activities, and its friendliest people.