How was the Grand Canyon made?

At one time. the ocean covered much of the Rocky Mountain region.. A narrow trough of sea. ran from Alaska to Mexico. Sand and silt collected in this basin. Ages later. it was to form layers: of shale and sandstone. All this happened when the world was young. Only one‑celled creatures;. simple sponges and tube‑like worms were there to leave their remains in the early deposits„

Millions and millions of years later. part of the western continent began to rise. The old earth humped her back. The ocean returned to its basin. The sandstone. limestone and shale rocks rose high above sea level. Meantime. the first simple creatures‑ had changed and developed. The trilobites ancestors of the crabs  lobsters. spiders and insects. had arrived

Several times‑ again the sea invaded the edges of the western continent. Each time. more limestone and sandstone were added to the earths crust. With the last invasion the Sierra Nevadas began to lift up their heads. And 100 million years ago. the proud tops of the Rockies began to make a ridge down the western side of the continent. Deep ancient layers of rocks from below were lifted high above the level of the sea. Countless strange animals ware striding over the land and swimming in the seas. The first birds were flapping their huge pinions.

Fifty million years . the western continent was still far from quiet. There were seething volcanoes beyond anything we can imagine. Tones of brown‑black lava poured out upon the Columbia Plateau. It covered 200..000 square miles. sometimes to a depth of 5000 feet.. The Rockies grew taller. the gentle Coastal. Range and the snowy Cascades began to poke up their noses. The land bore flowering plants. cereals and grasses. Modern animals took over the world from the prehistoric monsters.

The western part of the‑continent was at last ready for a busy river to begin a job of artwork sand engineering. The river was the Colorado. The artistic job of world was the Grand Canyon. The job was started fifty million years ago

The source of the river was on the western slope of the growing Rockies. It ran down the high ground westernward to the gulf of California. It was always a swift river. Its current was strong. And its path lead through layers of ancient sandstone. These are soft rocks: The river could wear them away.

Bit by bit it cut deeper into its soft bed and banks. It cut out thousands of gorges as it twisted and turned. In fifty million years. the swift current in some places has dug its bed a mile deep. Steep cliffs and terraces of sandstone line its banks. It has worn away rocks that took hundreds of millions of years to build.