Great Sand Dunes National Park Quarter
The Great Sand Dunes National Park and Preserve is not just sand dunes! The park's borders enclose an amazingly diverse set of biomes and landscapes. On the other hand, the dunes themselves are awesome...the tallest in North America.
The sand dunes are in a circular area at the base of the Sangre de Christo Mountains in Colorado. A dune can be 750 feet tall, about the height of a 75-story building (though it will look small if you see it from the top of nearby Mount Herard, at 13,297 feet)!
Sand dunes can't get this tall without water to hold them together. The sand is dry on the surface, but moist underneath. In fact, some flowers actually grow in the sand because of this moisture. Where does it come from?.
In addition to rainfall (about 11 inches a year), two creeks run from the snowy peaks down the mountains and wrap around the dune field on the north and the south sides to provide this water.
The reason why the creek water doesn't just sink into the sand is because of the water table below the surface. It allows the water to move sideways into the dunes instead of just downward.
It also keeps the sand dense but pliable. As water passes over the sand, it forms little underwater dunes that soon break, making waves. This is one of the few creeks in the world that has waves every 20 seconds, sometimes a foot high! (Okay, you won't be surfing in those waves...but there's always sand surfing here!)
Rain washes some sand from the dunes into the creeks. The creeks carry the eroded sand away to the sand sheet west of the dunes, but it doesn't stay there. Wind blows the sand east, back onto the dunes. Natural recycling!
The park and mountainous preserve hold many environments, even tundra above the tree line. This place is truly a national treasure! Learn more on the Great Sand Dunes Quarter page.