5 Incredible Fun Facts About Great Sand Dunes National Park

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Podcast Episode Overview

Tucked between two of Colorado’s most towering mountain ranges is a landscape that feels almost fictional. 30 square miles of dunes rising taller than the Gateway Arch, somehow thriving in the heart of the Rockies — it’s a place that you have to see to believe.

In this episode, we’re digging into some fun facts that will show you why the Great Sand Dunes National Park is so incredible – including how it came to be and why it almost didn’t survive.

In this episode, we cover:

• How the tallest dunes in all of North America came to be
• The three main dunes: Star Dune, Hidden Dune, and High Dune
• The rare surge flow phenomenon that can send waves 12 to 20 inches high
• The naturally magnetic black sand called magnetite, and why a lightning storm can make your compass spin
• Why geologists still can’t agree on how old these dunes actually are
• The Great Sand Dunes gold rush of the 1920s — and the local women’s organization that saved the park from becoming a gravel pit
• How a water development threat decades later nearly destroyed the sand recycling system
• The 2004 legislation that made the park four times larger and solidified its protection

Your task for today: Find the nonprofit partner for your favorite national park, follow them on social, and let us know who they are over on the @DirtInMyShoes Facebook or Instagram so we can support them too!

Planning your own Great Sand Dunes adventure?

• 5 Things You Can’t Miss On Your First Visit to Great Sand Dunes: https://www.dirtinmyshoes.com/5-things-cant-miss-first-visit-great-sand-dunes-national-park/
• Episode 146: Prepare to be Wowed at Great Sand Dunes National Park! (Best Tips + Activities): https://www.dirtinmyshoes.com/exploring-great-sand-dunes-national-park-best-tips-activities/
• Master Reservation List: https://www.dirtinmyshoes.com/list/ 
• National Parks Checklist: https://www.dirtinmyshoes.com/national-parks-checklist/ 
• Trip Packing List: https://www.dirtinmyshoes.com/pack/ 

Great Sand Dunes Fun Facts: Everything That Makes This Park So Incredible

Would you believe us if we told you that there’s a REAL national park that looks like a fantasy novelist dreamed it up? We sure hope so, because it’s not fictional. The Great Sand Dunes National Park is one of the most unreal places on the continent, and it’s home to the tallest dunes in North America.

Hidden between two walls of 14,000-foot peaks in southern Colorado, the tallest dunes rise more than 750 feet from base to crest — taller than the Gateway Arch in St. Louis, more than twice the height of the Statue of Liberty. 

But the park has a rich history – including how it came to be and why it almost didn’t survive. Let’s dig into some of that history with a few fun facts!

Fun Fact #1: The Dunes Are a Geographical Phenomenon

Colorado is home to 53 of the 67 fourteeners in the contiguous United States. For context, California has 12, and Washington has two. The sheer density of extreme peaks in this state is staggering. And yet, the tallest dunes are here too. 

But they don’t feel like they should be. The state is essentially split down the middle. In the eastern half, you have flat, high plains, and the western half has wall-to-wall mountains. Right in the center of that mountain spine, the Rockies split into two distinct ranges — the San Juan Mountains, and the Sangre de Cristo Mountains. 

The most mind-boggling part of it all? A giant valley the size of Connecticut — the San Luis Valley. That valley is where everything comes together. 

Even though the geography of Colorado is interesting and unexpected to say the least, it actually created the perfect storm for the dunes to form.

Mountains, Valley, Wind, and Water

Over millions of years, rivers and creeks carried sand and sediment out of those mountains and deposited it into the valley, eventually filling an ancient lake called Lake Alamosa. 

The Rio Grande — yes, that Rio Grande — had its headwaters deep in the San Juans and brought a huge amount of that sediment down before the lake eventually drained south, carving a path that the river follows today.

Once the lake was gone, the sand had nowhere left to go but up. And with strong, constant wind…the tallest dunes in North America were formed!

Fun Fact #2: The Dune Field Is Only 10% of the Sand

Surrounding the 30-square-mile dune field for miles in every direction is an area called the sand sheet — and it’s hundreds of feet deep. They’ve drilled all over the place out there, and it’s just sand the whole way down!

But it’s buried under grassland, which means the visible dune field is just the tip of the iceberg. And that fact has a lot of people wondering…how old are these dunes, really?

The NPS offers a few theories. Some say the dunes are only about 12,000 years old and formed during the ice ages. Others say they formed after Lake Alamosa dried up, which would make them 400,000 to 500,000 years old. 

And given the sheer volume of sand in the sand sheet, they may be even older than that!

Fun Fact #3: Medano Creek Can Send 12–20 Inch Waves Every 20 Seconds

On the eastern edge of the dune field, two creeks flow out of the Sangre de Cristo Mountains — Medano Creek and Sand Creek. Medano flows south, Sand Creek flows north, and then both turn west, wrapping around the edge of the dune field.

Which basically means that even with wind, the sand doesn’t ever escape. It just keeps cycling through the system.

Where the Waves Come In

Where the creeks reach the western side of the dune field, and the sand gets recycled back in, the creeks themselves disappear. Medano Creek vanishes into the sand. Every particle of sand that falls into those creeks stays in the system.

Then comes the surge flow. The water carries a lot of sand, which creates tiny underwater ridges. Those ridges build into little dams, the water pressure breaks them, and you get a mini surge (a small wave) rolling down the creek about every 20 seconds. 

In a typical year, those waves are only two to three inches tall. But in a wet year, with good snowpack feeding the mountains, it can reach 12 to 20 inches — high enough that you’ll see people floating down the creek in tubes!

INSIDER TIP — Peak Medano Creek flow is typically around late May, but it varies year to year based on snowpack. If you’re hoping for the full wave pool experience, keep an eye on the snowpack totals in the San Luis Valley through the winter.

Fun Fact #4: Magnetite in the Sand Can Confuse Your Compass

Magnetite, another phenomenon of these dunes, is an iron-bearing mineral that’s slightly denser than regular sand. 

Because of that density difference, wind acts as a natural filter and separates the magnetite into stripes of black across the dune surface.

A concentrated vein of magnetite carries a strong enough magnetic charge that it can confuse a compass. And following a thunderstorm — when lightning can essentially supercharge the magnetite — that interference can get intense enough to send a compass needle spinning.

INSIDER TIP — We’ve seen some wild lightning storms here, but standing on the dunes during a thunderstorm is genuinely dangerous — you’re the tallest thing around, and there’s nowhere to shelter. If you see weather building over those peaks, get off the sand ASAP.

Fun Fact #5: Great Sand Dunes Has Been Saved Twice

Twice in the park’s history, people who loved this place had to fight to keep it from being destroyed.

The Gold Rush of the 1920s

In the 1920s, gold was discovered in the sand near Great Sand Dunes — and pretty quickly, mining operations along Medano Creek expanded beyond gold. 

Miners started diverting the creek and trucking off sand for construction and concrete. Great Sand Dunes was on its way to becoming Colorado’s most famous gravel pit.

But the local Chamber of Commerce pushed back for five years, but it was a women’s organization — the PEO, the Philanthropic Educational Organization — that finally built the momentum to act. 

The local San Luis Valley chapter escalated to the statewide organization, then went national, lobbying through letters, meetings, and tours of the dunes themselves. In 1932, President Hoover signed a declaration making Great Sand Dunes a national monument.

The Water Threat of the 1980s and 90s

Decades later, the dunes needed saving again. Water development companies proposed pumping groundwater from just outside the park boundaries. But this could have easily caused the creeks to vanish underground. 

Local residents once again joined together to fight for the park. In 2000, Congress passed legislation authorizing the purchase of land from the water developers. In that same legislation, Congress also authorized the expansion of Great Sand Dunes into a full national park — four times the size of the original monument! Then in 2004, it became official.

Go Find Your Park’s Nonprofit

Our parks depend on the voices and support of people who love them. Some wouldn’t be here without them. That’s why we donate a portion of our income to nonprofits that work with the parks, so when situations like these arise, we can help save and preserve our parks.

Your task for today: look up your favorite national park and find out which nonprofit organization partners with it. You don’t have to donate right now. Just find them. Follow them on social. See what they’re working on. And let us know who you found over on the @DirtInMyShoes Facebook or Instagram page!

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Links Mentioned in This Episode:

• 5 Things You Can’t Miss On Your First Visit to Great Sand Dunes
• Episode 146: Prepare to be Wowed at Great Sand Dunes National Park! (Best Tips + Activities)
• Great Sand Dunes Sand System Overview
• Dune Types at Great Sand Dunes
• Geology of Great Sand Dunes
• Hydrology at Great Sand Dunes
• Magnetite Sand at Great Sand Dunes
• Volcanic Origins of Great Sand Dunes
• The Great Sand Dunes Gold Rush
• The Ladies P.E.O. and Great Sand Dunes
• National Monument and National Park Status
• Medano Creek
• Great Sand Dunes FAQs
• Introduction to the Geology of Great Sand Dunes

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