http://www.scenic.com/visitor-information/grand-canyon/history | The Grand Canyon is one of nature’s wonders, drawing millions of visitors every year from around the globe. Learn how the canyon was formed and about the ongoing debate among scientists about the true age of this massive “hole in the ground.”

1. The Formation and Age of the Grand Canyon
The Grand Canyon is a geological marvel, drawing millions of visitors every year from around
the world. It’s no wonder—the canyon’s brilliant layers of red rock make this giant “hole in the
ground” a stunning sight.
Visitors can choose from a huge range of activities in the Grand Canyon, including river rafting,
hiking, camping, Grand Canyon tours by bus, and awe-inspiring helicopter tours. Those who are
physically able may attempt a hike into the canyon, while others who want an easy stroll can
hike along the rim.
So, just how exactly did the canyon form and when? We’ll explore these and other questions
below.
Far, Deep, and Wide
At 277 miles long, and up to 18 miles wide in some places, the Grand Canyon is quite literally an
enormous hole in the ground. The canyon is a mile deep (over 5,000 feet) in some places, and is
so enormous it can be seen from space. Because there are such huge variations in elevation in
different parts of the canyon (rim to floor), the area boasts an impressive diversity of plants and
wildlife. In fact, five different ecosystems occurring between Mexico and Canada can all be
found in the park, including:
Boreal Forest
Ponderosa Forest
Pinyon-Juniper Woodland
Desert Scrub
Riparian (along the river)
The area is home to more than 1,750 plant species, 17 fish species, 57 species of amphibians and
reptiles, 91 mammal species, 373 bird species, and more than 8,400 insect species.1
How Old Is the Grand Canyon?
Scientists have hotly debated this question for more than a century. The big controversy has been
over when exactly the river started cutting through the rocks. Experts originally thought it started
5-6 million years ago, but later studies revealed geologic evidence suggesting that it may have
begun much earlier—as much as 70 million years ago. There are several dating techniques
scientists use to estimate the age of rocks, but interpreting the data can yield wildly different
estimates between scientists. It seems that the jury is still out in terms of the canyon’s true age,
but one thing is fairly certain: Some parts of the canyon are older than others.
Age of the Canyon vs. Age of the Rocks
One important distinction is the age of canyon itself versus the age of the rocks that make up the
canyon walls. The rocks themselves are estimated at around two billion years old, while the
canyon itself has been around only for millions of years (as mentioned above, there is no
consensus on exactly how many millions of years).

2. How Was the Canyon Formed?
It’s hard to believe that the giant chasm that is now the Grand Canyon was carved out over time
by water, but scientists largely agree that this is the primary mechanism by which the canyon
was formed. Other factors that contributed the canyon’s formation include wind erosion, frost
heaving, plate tectonics, and volcanism.
Tourism Statistics
There’s no doubt that the Grand Canyon is an important source of revenue for the state of
Arizona—in fact, in 2011, 4.3 million visitors to the park spent more than $467,000,000 and
supported 7,361 jobs.2
Beyond its income-generating potential, the Grand Canyon offers visitors from all over the world
a glimpse into a world unlike anything else—a priceless experience for many. The Grand
Canyon will undoubtedly continue to inspire millions more in the years to come.