How Mexico's Dunes Protect and Preserve

If you walk into the quiet halls of the Institute of Marine Sciences and Limnology (ICMyL) at the National Autonomous University of Mexico (UNAM), you might stumble upon a small yet extraordinary treasure trove. It isn’t gold, nor jewels, nor priceless antiquities. It’s sand. But this isn’t just any sand—it’s a carefully curated archive of sediment from deserts, beaches, and coastal plains, gathered over decades and sourced from all corners of the world. Welcome to the Dune Collection, a geological anthology that tells stories spanning billions of years, shaped by wind, water, and time.

The Dune Collection, unique in Mexico and among the country’s academic institutions, began in 2001 and now houses 250 samples—each one a granular testament to Earth's complex history. From Mexico’s Baja California Sur, Sonora, Veracruz, and Oaxaca to continental Chihuahua and even far-flung samples from New Zealand, the collection is a rich tapestry of environments and geographies. By 2015, it was formally recognized as the Institute’s Collection—a fitting honor for a resource that has become indispensable for research, education, and outreach.

Behind the Collection’s creation stands Juan José Kasper Zubillaga, a researcher at ICMyL, whose curiosity and diligence laid the groundwork for this sand repository. “It has been built through my own field collections and through generous donations from colleagues,” Kasper explains. This collaborative effort has allowed the collection to grow into something far greater than a set of vials filled with grains. It has become a scientific window into the dynamics of sedimentary environments—specifically, dunes.

Dunes, Kasper notes, are more than just picturesque landscapes. Whether coastal or continental, they are shaped by one critical physical agent: the wind. Without wind, dunes cannot form. They require eroded rock—particles ground down by time and nature—to accumulate in areas where natural basins trap the material. And while they are found in every latitude on Earth, their beauty and function often go unrecognized.

In Mexico, dunes are prevalent in both coastal and continental regions. Picture the Sonoran Desert, stretching across northern Mexico and into Arizona; the shimmering plains of Guerrero Negro in Baja California; or the sweeping sands of Chipehua, Oaxaca. Further east, the rolling dunes of Chachalacas and Laguna Verde in Veracruz provide yet another example of these ever-changing sedimentary systems.

But these dunes are not just geological marvels—they are vital protectors of life and land. “They act as a morphological barrier,” Kasper explains. “During hurricanes, dunes prevent the intrusion of seawater into inland areas. They form a critical transitional zone between the ocean and the continent.”

Habitats of Life, Time, and Climate

Dunes, it turns out, are alive in more ways than one. They provide habitats for a diverse array of organisms—many of them endemic. Reptiles, small mammals, and birds rely on these environments to survive, making their preservation essential. Yet, Kasper warns, misconceptions about dunes as recreational zones often threaten their delicate ecosystems. The rumble of four-wheelers across the sand may seem harmless to the untrained eye, but it can devastate habitats and disturb fragile balances.

Beyond their ecological role, dunes serve as archives of Earth’s climatic history. By studying sand composition, scientists can reconstruct ancient climates, trace sediment transport, and uncover the chemical transformations of minerals like quartz, pyroxene, and ilmenite. For Kasper, one mineral has stood out in particular: garnet. “We’ve realized that garnet is a mineral that helps diagnose certain sedimentary cycles,” he says, hinting at the revelations that lie within these seemingly ordinary grains.

The science of dunes is precise, down to where the sand samples are collected. Geological engineers examine three key sub-environments within each dune: the windward side, where grains are pushed upward by the wind; the crest, or peak, where energy peaks and sediment pauses; and the leeward side, where gravity pulls particles to rest. By analyzing samples from these distinct zones, scientists can decode the entire dune system—how it formed, how it evolves, and what it reveals about its surroundings.

The grains themselves offer further clues. “The variability of grain size reflects the dynamics of wind and water,” Kasper explains. Sand—also known as detrital sediment—forms through erosion, whether by water or wind. Composed primarily of quartz and feldspars, as well as fragments of other rocks, sand carries within it a geological fingerprint. In the lab, scientists determine the percentages of silica, iron, aluminum, and other elements, constructing what is known as the sample’s structural formula—its chemical composition and mineral identity.

Color, too, tells a story. The Dune Collection houses sands of dazzling variety—from the sugar-white beaches of the Yucatán Peninsula to the volcanic black sands of Oaxaca and the green-tinted shores of Veracruz. Their hues reflect their origins: black sands, for example, owe their color to minerals like magnetite, sourced from volcanic activity.

“The wonderful thing about the Mexican coast,” explains Lizeth Carlos Delgado, the Collection’s curator, “is that we have immense mountain ranges like the Sierra Madre Oriental and Occidental, each with its own geological history.” Volcanic giants like Pico de Orizaba have shaped the dunes of Veracruz, while the calcium carbonate sands of Yucatán tell a marine story, formed from ancient shells, corals, and marine organisms.

Some samples, like those from Oaxaca, trace their lineage back to rocks formed in the Proterozoic era—a staggering 1.5 billion years ago. “It’s fascinating,” Lizeth reflects, “to study a mineral that has endured since prehistory, concentrated here in these dunes.”

More Than Grains of Sand

The Dune Collection’s goals are as ambitious as they are inspiring. Lizeth emphasizes the importance of growth—adding more samples, expanding access, and fostering public awareness. Already, the collection serves as a hands-on resource for workshops at UNAM’s National School of Earth Sciences, where students learn to identify minerals and analyze sediment dynamics. It also plays a key role in public outreach events like Encuentro con la Tierra (Encounter with the Earth), which brings the wonder of Earth sciences to broader audiences.

“We want people to see that sand is more than just grains,” Lizeth says. “It has a history, a story to tell, and it can be studied in detail.”

In the end, what the Dune Collection offers is perspective. Sand—ubiquitous, overlooked, and often dismissed—is a record of planetary processes that have shaped Earth for billions of years. It is the product of mountains worn down, oceans retreating, volcanoes erupting, and winds blowing ceaselessly across the surface of our world.