The Canyon Echo That Answered Late
On the second afternoon of the hiking trip, twins Nolan and Maeve reached the edge of Whistler's Canyon, a deep, red-walled gorge that the guidebook promised had "an astonishing echo." Nolan cupped his hands and shouted, "Hello!" Nothing happened. He tried again, louder, and a few seconds later the canyon replied with a booming "Hello." Maeve grinned, and then she shouted, "Who wants pancakes?" Before the echo could answer, Nolan yelled, "I do!" and the canyon, which had been slowly working its way through the first question, suddenly roared back, "Who wants pancakes?" and then, a moment afterward, "I do!"
The twins quickly discovered that the echo was so slow that it mixed up every conversation. When Maeve shouted, "Is anyone out there?" and Nolan added, "Hello, Mr. Echo!" the canyon seemed to reply that someone was out there and that Mr. Echo was a hello. Then it said, "Pancakes!" for no reason at all, because one of their earlier shouts was still bouncing around somewhere.
Maeve, who liked science, figured out why it happened. Sound travels at a steady speed, she explained, and the canyon was so wide that each shout needed several seconds to cross it and return. Their next shout was already on its way before the first one had come back. She suggested that they take turns and wait for each reply before speaking again. They tried it. Nolan shouted, "Thank you!" and waited a long, patient time. Eventually the canyon answered, "Thank you," in a voice that sounded polite. The twins agreed that this was the best conversation either of them had ever had with a canyon.