The dramatic Lower Falls in the Grand Canyon of Yellowstone became even more dramatic in January when much of the thundering water was stilled in a frozen tumble of ice. The cascade is the tallest waterfall in Yellowstone National Park at 308 feet and its peak runoff in the spring has more than 60,000 gallons per second flowing over the falls. Much of its flow was temporarily stifled when we watched it from Artist’s Point last month but the remaining tumult of its waters filled the canyon with its spray as it continued its journey down the Yellowstone River.