Fill in the Blanks How the Grand Canyon was formeOnline version Fill in the blanks with the correct words to explain how the Grand Canyon was made by Amy Klingensmith 1 Arizona gorge slow canyons Rainwater erosion building river Colorado bigger million One of the biggest in the world is the Grand Canyon in the Southwestern United States in . A canyon is a deep or gully in the Earth . It usually has steep walls and most of the time there is a flowing at the bottom of it . The Grand Canyon is so big that if you took the world's tallest and stacked it on top of itself twice , the Grand Canyon is still deeper than that . The canyon was formed by the River . This process of water picking up dirt and rock and getting moved from one place to another is called . also helps the process of erosion . Scientists believe that the Grand Canyon started forming over 5 - 6 years ago . The process of erosion is very and continuous , which means that the Grand Canyon is getting .