It happened on a crisp cool morning in March 2002 while I participated on a geology field trip to Arizona with a couple of college colleagues and 15 of our students. After a fairly nondescript drive northwards from Flagstaff, Arizona, we came to a stunning sight. I’d read about this place ever since I studied geology as an undergraduate, and it has always an almost mystical appeal. In my home country of South Africa, I visited some amazing places, including Namibia’s Fish River Canyon, that should have prepared me for what I was about to see. Sometimes referred to as the “mini-Grand Canyon,” it lays bare more than one billion years of Southern African geological history.

But Fish River Canyon is a mere gash in the ground compared to the yawning spectacle before me that March morning—the Grand Canyon. February 26 marks the 100th anniversary of the official designation of Grand Canyon National Park, the 15th such park in the United States. Since 1919. But for centuries before that, uncounted numbers of visitors have traveled to northern Arizona to behold the incredible site which chronicles nearly two billion years of the geologic history of the planet.

Thankfully, visionaries like presidents Theodore Roosevelt and Woodrow Wilson were able to preserve the area for current generations to enjoy, wonder and research the colorful rock layers that expose much of the continent’s geological history.

Tourists come from around the world to marvel at the grandeur of the GC—almost 300 miles long, up to 18-miles wide and more than a mile deep. They stop at famous overlooks like Desert View and Yavapai Point, hike along the rim, and visit the geologic exhibits at the Geology Museum; a few even venture into the canyon itself —perhaps a few hundred or thousand feet down the South Kaibab or Bright Angel trail. Many visitors are aware that they are looking into the abyss of time, but can they really appreciate the fact that stretched out in front of them is more than 1.8 billion years of geology—nearly two thirds of the history of the planet itself. The rocks span time from more than 2 billion years ago in the deepest parts of the canyon to about 200 million years at the rim.

Admittedly, they don’t record all the details of this history. There are a few gaps—what geologists call unconformities, or time periods when the record of geologic history is missing. But let’s not quibble about the details. To stand at the edge of the Grand Canyon and gaze at layer upon layer of rock is a spiritual experience.

The Grand Canyon is truly a special place, a location of global importance because of its fundaments scientific value; a place of immense beauty, of awe-inspiring vistas. Everyone should experience this massive gorge at least once in their lives. But for a geologist it is a pilgrimage, a place to ‘feel’ geology, to immerse yourself in the glory of the science.

More than 5 million people visit the national park annually. In 1979, UNESCO designated the Grand Canyon a World Heritage Site. I have visited the site several times since 2002, once by rafting nine days down the Colorado River, the roaring waters of which helped carve the GC’s rock strata. I hope to visit many more times. It is good for my (geologic) soul.