We found Great Sand Dunes National Park is obviously, but very appropriately named. The size of the tallest dunes in North America and the vastness of the 30 square mile dunefield definitely steal the show. However, during our visit, we learned of so many eccentricities of Great Sand Dunes that really fascinated us and made the dunes seem much more than just a big pile of sand.
- Surge Flow – This is a rare phenomenon in Medano Creek that flows along the east side of the dunefield. In early summer the wide, shallow Medano Creek is at peak flow (May is prime and June is good) from the snowmelt coming down from the Sangre de Cristo Mountains. Because the whole creek bottom is sand, the water carves lots of grooves into the sand and little sand dams are built up. When the flow of the water knocks down these dams it creates a sudden rush of water. This is called surge flow and the “waves” can be up 18″ high when the flow is highest. By the time we were at GSD in late August, all snow had melted from the mountains and the creek was very low (about 1″). So we did not hit surge flow season. Which was probably best for us because a full creek attracts huge crowds, long traffic lines and lots of kids playing and floating in the waves.
- Flowers – One season we did seem to hit was wildflower season. They were everywhere! And it was gorgeous! I was surprised to see tons of different kinds of flowers blooming along our mountain hike to Music Pass and Upper Sand Creek Lake. But the real surprise was in the dunes. There were bright yellow prairie sunflowers in full bloom growing right out of the sea of sand. And there weren’t just a few here and there. The flowers were in huge patches all across the valleys of the dunes. And they all faced east towards the rising sun.
- Gold mining – In the 1920s rumors of gold hiding within the dunes were published by local newspapers. This caused a mini gold rush and mining operations started to spring up along Medano Creek. Local residents were scared that these big operations would destroy the environment. Fortunately, although small amounts of gold were recovered from the sand, the work was too labor intensive and the payout too small.
- Lightning – Apparently the dunes are an awful place to be during a thunderstorm. When lightning does hit the dunes it melts the grains of sand together at that spot to form a cylinder of fused sand. As the winds blow away the surrounding sand the cylinder is exposed and sticks out of the dunes. Despite my best efforts I could not find one of these crazy lightning sculptures.
- Endemic Insects- There are 1,000 known kinds of insects and spiders living in GSD, and at least 7 types of insects that are only found in GSD and nowhere else on Earth.
- Great Sand Dunes Tiger Beetle – Adults actively scavenge on the sand and larvae stay still and ambush prey.
- Circus Beetle – When threatened, these beetles appear to stand on their head and release a smelly chemical towards the enemy.
- Werner’s Ant-like Flower Beetle – Half the size of a pencil eraser.
- Clown Beetle – With a round body, this beetle can roll with the wind to a new spot.
- Noctuid Moth – Not much is known about this moth.
- Robber Fly – Often seen feasting on other flying insects during the heat of the day when all the crawling insects have abandoned the hot surface sand.
- Sand Recycling – The dune formation itself is incredible. In a nutshell, the sand is blown in from the San Juan Mountains over 65 miles to the west and is deposited on the dunefield as the winds weaken and start climbing to go over the Sangre de Cristo Mountains to the east. So that’s how sand first gets onto the dunes. Then over time northeast winds blow the sand from dune to dune until they are blown into Medano Creek which runs along the eastern edge of the dunefield. The sands are carried by the creek and deposited when the creek peters out southwest of the field whereupon they are blown right back onto the dunefield. So the environment recycles the sand! Another cool thing is that when Medano creek is dry during the winter the sand is sometimes blown from the dune field right across the creek. And without being captured by the water it ends up on the other side to form what they call the Escape Dunes at the base of the Sangre de Cristo Mountains. Research suggests the dunes are less than 440,000 years old, but their exact age is unknown. The dune field is no longer growing in area, but sand recycling means the tallest dunes may be getting taller. When we were trekking into the dunes the first night we could see the wind whipping over the ridges and throwing waves of sand down with it. These sand BBs didn’t feel too good when we were nearing the top, but we powered through.
The Visitor Center does an awesome job laying out all these really cool facts of Great Sand Dunes to really show how the dunes are multidimensional. We found all of it fascinating. It was very clear by the end of our visit that the dunes we explored were so much more than piles of sand – they were a home for critters, a vital element of the of the environment and a protected treasure for everyone to enjoy.
And I’ll leave you with a bonus quirk we learned from the ranger that is again unique to Great Sand Dunes… All other NPS sites require 6 inches, but when burying poop in the backcountry of the dunes you are required to go only 1 inch. This is because if you bury it too deep, the wind will not reveal and decompose it over time and instead it will fossilize. And as the ranger said, that’s a fossil that no one wants to find!