The question is, "Was Grand Canyon formed slowly over millions of years or much shorter time?" For over a century, geologists who believe in the evolutionary theory have tried to explain how Grand Canyon might have formed. Suggestion that the Colorado River eroded the canyon slowly over millions of years, have shown to be unworkable.
We now have good evidence that canyons can be created in a much shorter time period. On May 18, 1980, a volcano in Washington state called Mount St. Helens erupted and produced fantastic mud flows reaching speeds of 90 miles per hour, picking up sediment and rock, devastating 150 square miles of forest. These mud flows laid down enormous amounts of sediment covering the area like a stack of pancakes, resulting in a sediment pile up to 600 feet thick in places.
But what happened on March 19, 1982 when Mount St. Helens erupted again was that new mud flows eroded large canyons as they scoured the countryside. One of these canyons is now called "Little Grand Canyon" and is a 1/40 scale model of the real one. This new canyon even has side canyons which look essentially the same as others elsewhere. This canyon was formed in one day.
Creationists believe the Grand Canyon was formed in the same fashion. First rock layers were laid down during the worldwide Flood and volcanic upheaval of Noah's day (Genesis 6-9).
The canyon itself (Grand Canyon) was carved out in a later post-Flood catastrophe. It does not take long to form rock from sediments. Three-quarters of the earth's surface is covered with sediments that were laid down by water and later hardened (called sedimentary rocks). Mouint St. Helens gave us a glimpse of such an event in a much smaller scale and shows that the Grand Canyon fits well in the framework of God's Word and the great worldwide flood of Noah's day.