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Published on Friday, September
24, 2021
 By Victoria Torley Hi there, all you folks on the coasts. I bet you have sandy soil . . . First, we have two types of sandy soil, white – or calcareous sand – and black – or volcanic sand. Where did they come from? Well, the white stuff came from the parrot fish. And that deserves some explanation. Parrot fish are vegetarians, which confuses many people who think they are nibbling at the calcification around corals to get at that meaty snack inside. Nope. What they are really doing is nibbling a tiny bit of calcification to clear a path to the algae that squirms its way between the little nubs of coral. It goes like this: “Oops, didn’t mean to chip your house; I was just trying to remove that algae buildup, so it won’t smother you.” “Gee, thanks,” replies the coral, “it was getting a bit hard to breathe.” In the process of cleaning up the coral, the parrot fish probably gets indigestion. After all, it can’t actually eat coral ‘shells,’ so they pass through the digestive system and are excreted. A single mature parrot fish can make about two hundred pounds of lovely white sand every year.
So, black sand. For that, we need volcanism, and we have a lot of that in Costa Rica, but since our volcanoes aren’t putting out enough lava to reach the sea, let’s look at Hawai’i instead. Hawai’i has some heavy-hitting volcanoes, and the lava flows directly into the sea in many places. As it flows away, it cools, but we are still talking 400F when it hits the water. And the water is cold. What happens? The lava cools rapidly and fractures into chunks large and small. The waves batter it around, and the pieces get smaller. More lava flows in and complicates the process. In the end, you have towering cliffs of lava in Hawai’i and smaller cliffs at Playa Hermosa. But the ocean isn’t done. It keeps hammering the rocks at Hermosa (and other places), breaking them up, grinding them into sand. Voilŕ, black sand beaches. Well, it looks as though most of our volcanic beaches are on the Pacific side of our lovely country. That’s because the lava flowed west. And our Caribbean beaches? Shallow water is perfect for coral growth.  Oops, I spent so much time on sand that there is no time for plants. Except for those pretty palm trees . . . Ah well, there’s always next week. ------------ Editor's note: More information on this article, Ms. Victoria Torley, gardener columnist, can be reached at victoriatorley1@gmail.com Real
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