It melts and leaves a canyon
Glen Canyon was flooded to create Lake Powell in the 1960s. This was part of the construction of the Glen Canyon Dam, which is located near Page, Arizona.
If someone is standing in the canyon while you shout, the sound waves will bounce off the canyon walls and create an echo. The person in the canyon will hear the original shout followed by the echo, which can create a cool and amplified sound experience.
I don't know who you think "they" are, but humans did not create the Grand Canyon.
Echo Canyon was formed by erosion from the waters of Leidy Creek, which cut through the sandstone rock over millions of years to create the unique canyon shape. The canyon is known for its excellent acoustics, which amplify sound and create echo effects, hence the name "Echo Canyon."
The Colorado River and erosion helped to create the Grand Canyon.
Over the course of more than 17 million years, the Colorado River gradually eroded away sediment and rock to create a canyon.
Erosion over thousands of years.
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wind
By the use of time, water and an occasional flood.
canyon