Lençóis Maranhenses National Park (Parque Nacional dos Lençóis Maranhenses[a]) is a national park in Maranhão state in northeastern Brazil, just east of the Baía de São José. Protected on June 2, 1981, the 155,000 ha (380,000-acre) park includes 70 km (43 mi) of coastline, and an interior composed of rolling sand dunes. During the rainy season, the valleys among the dunes fill with freshwater lagoons, prevented from draining by the impermeable rock beneath. The park is home to a range of species, including four listed as endangered, and has become a popular destination for ecotourists.
In July 2024 the site was declared a UNESCO World Heritage Site for its exceptional beauty and the fact that it is a unique natural aspect in the world.[4]
I had no idea such a place existed in Brazil.
Wetlands and White Sands – what could they possibly have in common? (Besides a shared rhyming scheme, of course!) Since today is #WorldWetlandsDay, let’s dive in…
Believe it or not, this landscape used to be dominated by wetlands. Long before our sweeping gypsum dunes formed around 10,000 years ago, the Tularosa Basin was home to a massive lake surrounded by mud flats and grasslands. This lush watering hole attracted Ice Age mammals including American lions, Colombian mammoths, dire wolves, Harlan’s giant ground sloths, and even humans!Lucky for us, the mud that these predators and prey crisscrossed each day was the perfect canvas to capture their movements. Even as the Ice Age ended and the Tularosa Basin warmed and dried, creating our namesake gypsum dunefield, their experiences were cemented in the soil beneath the sand. Today, White Sands is home to the largest collection of fossilized Ice Age mammal footprints in the world. Although we’re far from our days as a wetland, fragments of stories from this time are told through the medium of fossil trackways, redefining our human history and revealing the lives of this land’s first inhabitants.Wetlands are crucial ecosystems for biodiversity, freshwater availability, and climate adaptation. Due to the interconnectedness of our natural world, even “drylands” like White Sands rely on the health of our wetlands. Learn more about wetlands and how and why you should protect them here: https://www.nps.gov/subjects/wetlands/index.htm
NPS Illustration / Karen Carr White Sands National Park
Very similar to the Brazil sands.
Our inaugural “No Stupid Questions” post received a great follow-up question that we thought deserved its own post… Marissa asked, “Why is the white sand concentrated to the area the park is in?”
We may be biased, but we think there is nothing stupid about this question! As we covered last week, gypsum sand is extremely rare, and gypsum dunes are even rarer. The Tularosa Basin is home to the only gypsum dunefield of this size because of the convergence of several geographical coincidences. First, an ancient sea deposited massive amounts of gypsum here several hundred million years ago, providing the basic material to form the dunes. Next, tectonic plate movement created the Tularosa Basin, which is a closed basin; picture a bathtub without a drain – once gypsum-infused runoff from the mountains reaches the basin’s low point, there’s nowhere else for it to drain, so it gathers into a seasonal lake or playa. This playa provides a nursery for selenite crystals to grow and then eventually break down into gypsum sand.Finally, a hidden feature of this incredible landscape provided the final ingredient: a shallow water table! Throughout the dunefield, the water table is a mere 12-36 inches below the surface, and it keeps the dunes at about 99% humidity. The groundwater also acts as an anchor, holding the dunes together and cementing them to the earth. At any given time, only the top couple of inches of sand are dry enough to be picked up and blown away by the wind. It’s this geographic anomaly that allowed 275 square miles of gypsum sand to pile up and stick in the Tularosa Basin.
Hit us with more of your “stupid” questions in the comments and you, too, may be featured in a future edition of No Stupid Questions! Learn more about the park, including the geology and hydrology that make the dunes possible, on our website: https://www.nps.gov/whsa/learn/nature/index.htm
White Sands background.