A sandfall! This is amazing. What might be going on is when it rains in the desert the water isn’t absorbed quickly and mixes with the top layer of wet sand which can form moving sand rivers and waterfalls. (Source)
Early April in the Rocky Mountains, the majestic peaks are still snow-covered while the lower elevations, including the lakes and rivers have melted out. I was walking along the riverbank when I saw a dark form lying on the bottom of the river. My first thought was a deer had fallen through the ice so I wandered over to investigate…and that’s when I saw the long tail. It took me a few moments to comprehend what I was looking at…a full grown cougar lying peacefully on the riverbed, the victim of thin ice. I tried to capture the eerie feeling I felt at the time as best I could.
Location: Waterton Lakes National Park, Alberta, Canada