Tower Creek slides over a lip of Eocene conglomerate rock and falls 132 feet in one clear, straight drop. That is why it is called Tower Fall and not Tower Falls. The water hits the rocks at nearly 100 miles per hour. The wind-torn edges of the water column and the impact on the rock create a steady cloud of mist. The narrow canyon below the fall angles off to the east-northeast and ends at the Yellowstone River. There is a rainbow visible in the mist only around the summer solstice when the sun rises at its northernmost position. The sun needs to light up the mist from a low angle up the canyon to create a rainbow. The rest of the year when the sun rises farther south it does not light the mist until its angle is too high to see a rainbow.