By Jonny Lupsha, News Writer

Officials will revisit Grand Canyon safety policies after an onsite suicide, USA Today reported. A 28-year-old man jumped to his death last week at Grand Canyon West. Despite this tragedy, the natural wonder is a world-renowned tourist attraction.

The USA Today article said that the tourist who committed suicide at the landmark did so by jumping to his death from the Grand Canyon Skywalk, which overhangs the cliffs in a horseshoe shape. Grand Canyon spokesperson David Leibowitz was quoted as saying that nearly 10 million people have visited Grand Canyon West since 2007, yet this is the first death associated with the Skywalk. The numbers speak for themselves: generally speaking, death is rare at the Grand Canyon and it remains an awe-inspiring sight to millions.

Grand Canyon by the Numbers

Understanding the majesty of the Grand Canyon proves difficult in pictures. It may be helpful to consider its size in numbers instead.

“A mile deep, nine to 18 miles wide, and 277 miles wide, this canyon carved by the Colorado River may well be the most celebrated geological feature in the United States,” Ford Cochran, Director of Programming for National Geographic Expeditions, said. “It is among the most celebrated on Earth.”

To better comprehend the size of the Grand Canyon, one only need look at its weather. It’s so deep that the weather changes significantly throughout it. “Temperatures on the Colorado River at its base average more than 20 degrees Fahrenheit warmer than temperatures on the canyon rim,” Cochran said. “At around 8,000 feet, the average North Rim elevation is 1,200 feet higher than the South Rim’s at 6,800 feet. Temperatures on the North Rim, therefore, run about five degrees cooler than on the South Rim.”

Cochran said that he once stood in a snowstorm along the South Rim of the Grand Canyon, looking down at a sunny Colorado River. Later that day, temperatures on the river reached the 60s. Another meteorological anomaly dependent on the size of the area is its rainfall. “Annual precipitation at Phantom Ranch at the bottom of the canyon averages only about nine inches, while the rims get nearly twice as much, with the North Rim getting more.”

The deepest part of the Canyon—Vishnu Schist—is nearly two billion years old.

The Secrets under the Grand Canyon Supergroup

“During a mountain-building event 1.7 billion years ago, old sedimentary rocks were buried miles deep and metamorphosed into schist,” Cochran said. “In places along the Colorado’s banks, the Vishnu Schist was intruded by granitic magmas that formed the Zoroaster Granite.”

Then, Cochran said, material overlaying the Vishnu Schist was eroded and the basement rocks returned to the surface before being buried again under rocks known as the Grand Canyon Supergroup, which are still visible today.

These rocks came to the area over a span of almost 500 million years, “from 1.2 billion to 740 million years ago,” he said. “Sandstones, shales, mudstones, conglomerates, limestones, and other sorts of sedimentary rocks collected in the interior sea […] that covered interior portions of Laurentia.”

Laurentia was the enormous prehistorical craton that forms the core of the current North American continent. Eventually it faced such upheaval from drift and erosion that the Grand Canyon Supergroup rocks washed down from areas as far away as Lake Superior and the northern Rockies to rest above the Vishnu Schist. This piling of rocks upon rocks is known as “The Great Unconformity,” and is one of the deepest, oldest phenomena of the Grand Canyon.

Geologists and cartographers have spent centuries unraveling the ancient mysteries of the Grand Canyon. It sheer scope defies belief, with its wildly different weather patterns from one part of the site to another. In turn, wonders like “The Great Unconformity” give us a sense of the massive scale of Earth’s land masses—and their shifting plates and rocks—from Pangaea to today.

Ford Cochran contributed to this article. Mr. Cochran is Director of Programming for National Geographic Expeditions. As an undergraduate at William & Mary, he studied English literature. He then took graduate courses in Earth Science at Harvard University and earned a Master of Philosophy degree in Geology at Yale University.