Alluvial Fan

We had seen the sign to the alluvial fan area at Rocky Mountain NP several times as we entered the park. We had even seen an overall shot of the area when we were driving the Trail Ridge Road (look at the left-hand side on that photo). However, we never stopped there to hike until close to final days of our stay at the park in 2019. Are we glad we spent some time exploring the area!

The National Geographic Society defines an alluvial fan as “a triangle-shaped deposit of gravel, sand, and even smaller pieces of sediment” (called alluvium). This phenomenon occurs when water flows down on mountains and canyons. In the case of the Rocky Mountain NP, this alluvial fan happened on July 15, 2018. The Lawn Lake Dam broke and released over 200 million gallons of water down the mountain. It flooded all the way down to Estes Park. The boulders you see on the photos here and in the area are the result of the water strength. None of this was here prior to the formation of the alluvial fan. Trees and boulders simply came down along with the water.