Just after dusk on Aug. 14, at an amphitheater in Mount Rainier National Park's Cougar Rock campground, a deep grumbling sound began to drown out a park ranger who was regaling visitors with an interpretive lecture about the park's natural wonders. The rumble quickly grew to a freight-train-like roar. That's when the ranger ran to a creek near the amphitheater and saw a large flow of mud and debris surging down the normally placid channel.
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