Geology Home Page physical geology historical geology planetary gems
Roger Weller, geology instructor
by Yvonne Ochse
Nature’s Beautiful and Dangerous Passages
Like many things, the best and most beautiful things in the earth’s geology take millions of years to form. The world’s slot canyons are undeniably among the most stunning of the things nature has to offer.
Remarkable feats of creation, slot canyons are formed over the course of millions of years as bits of rock, sediment and water carried via flash floods erode deep channels into the earth. These channels, which are always much deeper than they are wide, are generally carved through sandstone, although slot canyons can also be found in granite, basalt, and limestone.
The entrance to a slot canyon might appear as little more than a narrow, jagged gap in the earth. Some of the most visually stunning canyons are only three feet or so wide at the top, yet their widening bottoms can fall away to three hundred feet... and they get deeper with every rainy season. There are countless numbers of slot canyons around the world, but they are not at all common when you consider the enormous size of our planet. This is because geologic conditions‑‑ soil, weather (rainfall, in particular), etc.‑‑ must combine to create an environment specifically conducive to their formation.
At the beginning of every slot canyon is a natural wash, a dry creek bed or gulch that temporarily fills with water after a heavy rain. It is at this point that heavy rainfall, often as part of a desert’s seasonal monsoons, finds a tiny crack and begins to make that crack larger. Instead of thinking in terms of a slot canyon that already exists, imagine a piece of cracked desert land, densely-packed and too dry to soak up the intermittent rainfall of a desert climate. During a heavy storm, the rain rushes over boulders, scrubs, and the ground’s surface, where it finds and works ceaselessly at those cracks; like electricity, the water finds the path of least resistance. This, of course, is the largest crack, the same one that becomes deeper over the course of millions of years as these floods scour the sandstone and cut a path deep into the rock. Pebbles are caught and trapped, and the water flows around them until they, too, are loosened and washed away as the crack widens. These objects‑‑ rocks, boulders, etc.‑‑ are themselves cutting tools, and with every bit of movement they help enlarge the opening. The larger the channel becomes, the more violet the flood, and the more the water is filled with debris‑‑ rocks and branches of all sizes, dirt, more boulders, sometimes even logs. It is a never‑ending natural method of sculpture that man is literally able to measure over the span of years via the depth of some of the world’s more popular slot canyons.
The largest slot canyons in the world are found in Australia, but some of the most popular are in the United States. Although Utah has the heaviest concentration (particularly in Zion National Park and North Lake Powell), the most famous is Antelope Canyon in northern Arizona.
Image 7: The Grand Canyons Region (map)
Seen from above, slot canyons look like little more than slashes at ground level, yet exploring them reveals a world of wonder, a palate of creation unequaled by anything else.
On a canyon floor, the light filtering from far above reveals colors and striations the likes of which are available in no other type of geologic formation. The rock seems to glow, with graceful swirls of magical reds, purples and soft white curving around striated, water‑smoothed edges in unceasing patterns that emulate the liquid that forged them. These twisting, otherworldly passageways widen and narrow as if by whim, both horizontally and vertically. The turns along a canyon’s curving path can bring a visitor in and out of areas as dark and constrained as they might be filled with light and space.
Amid this beauty, however, lies a very real danger for the thousands of people who visit and hike these natural wonders on an annual basis. The same flash floods that created these unbelievably beautiful slot canyons can, nearly as quickly as an indrawn breath, literally kill. By the time a hiker hears the water‑‑ a sound that’s reported by the very rare survivor to be “thunderous”‑‑ it’s far too late to find safety.
These flash floods are not easy to predict, because a flood’s point of origin is most often a thunderstorm many, many miles away. This means that these dangerous floodwaters may have traveled for as long as ten hours, gaining speed and debris along the way, before they come crashing through the same slot canyon in which an oblivious group of hikers (above whom the bright, blue sky remains deceptively clear) trudges happily along.
To highlight the unpredictability of flash floods, Buckskin Gulch in Utah, the longest and deepest slot canyon in the southwest, is labeled by many tour companies as being an “easy hike,” while being simultaneously listed as eighth on Backpacker.com’s list of the 10 Most Dangerous Hikes in America. A line from their October 2008 article really says it all: “Should thunderstorm‑bloated flood waters come charging down the tunnel, you're no better than a bug in a firehose.” Potential hypothermia adds to the risk. At the entrance, hikers might enjoy‑‑ assuming one welcomes the heat‑‑ temperatures that exceed ninety, or even one hundred degrees. But the canyon floors are often dim, chilly, and damp, and inexperienced and unprepared hikers sometimes find themselves facing quicksand or wading through cold, waist‑ or chest‑high water, with no fast way to warm up afterward.
When only six inches of fast‑moving water can yank a person off his or her feet, imagine the power behind tons of debris‑soaked liquid crashing through passages only a yard or two wide. According to one government site, flash floods are the number one cause of thunderstorm‑related deaths nationally, and there have been thirty‑one flash flood related fatalities in Utah alone since 1950. On August 12, 1997 eleven tourists drowned in famous Antelope Canyon, Arizona when it was filled by the floodwaters from a earlier thunderstorm seven miles upstream. Although there were wooden ladders in the canyon, they were decimated by the flood. According to Climb‑Utah.com, two of the bodies have never even been recovered. Today, Antelope Canyon has bolted‑down ladders along with other safety features, but the danger is, and always will be, imminent.
There is beauty and unmatched splendor to be found in these sensational geologic creations, but one has to wonder if visiting them firsthand is worth the risk of having a slot canyon be the last thing you see in your life.
Image 18: Antelope Canyon
Image 1: Antelope Canyon.
http://en.wikipedia.org/wiki/File:USA_Antelope-Canyon.jpg - Photo by Lucas Löffler (Wikipedia Commons).
Image 2: Antelope Canyon.
Photo by Luca Galuzzi (Wikipedia Commons). Permission obtained via Wikipedia instructions.
Entrance to Lower Antelope Canyon:
Photo by Matthias Kabel (Wikipedia Commons).
Entrance to Upper Antelope Canyon:
Photo by Lisa Rimlinger (used by permission).
Flood debris in a slot canyon - http://picasaweb.google.com/lh/photo/anaaqgIH_y1B7zYg5HOiHg?feat=embedwebsite
Texas - Austin Sierra Club -
Used by Permission
Map of the Grand Canyons Region
Hikers in narrow slot canyons -
© Ron Reznick
© Ron Reznick
Canyon, Flooded to the Rim -
© JD Rose
Canyon, Flooded to the Rim -
© JD Rose
Hiker in Tent Rocks, Northern
New Mexico -
Used by Permission of Kevin Gong (http://www.kevingong.com)
2 Hikers in Spooky Gulch, 4
(Usage rights purchased from istockphoto.com)
A hiker chest-deep in water in
Sundance Canyon, Arizona - Canyoneering Adventure Blog -
Swimming in Black Hole, White
Canyon, Lake Powell -
Lower Antelope Stairs
Photo by “Moondigger” (Wikipedia Commons)
© Ron Reznick
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