Q. In a recent news story I saw, the writer claimed the “hoodoos” in Utah’s Bryce Canyon and other places in the West were the result of the Great Flood mentioned in the Old Testament. Their apperance is, of course, the result of a flood or fast-running water but additional information would be appreciated.
— Bud Ridings, of Greenville
A. I know this will upset biblical literalists, but as astronomer Carl Sagan would have said, the creation of those strange and beautiful rocky artworks were mill-yuns and mill-yuns of years in the making, starting long before even the ancestors of modern humans popped up in Africa.
But as for what formed them, don’t be too hasty in crediting a monumental flood, Noah or no Noah. Rather than a prehistoric tsunami or some raging river, hoodoos actually have formed over the ages by slow processes that rival the excitement of watching paint dry: frost wedging and acid rain. And, although the average tourist would be hard-pressed to notice, these natural forces continue to carve away at these awe-inspiring attractions. Here’s how, according to the U.S. National Park Service.
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First, for those who don’t have the slightest idea what I’m talking about, maybe hiker Sky Barsch Gleiner can give you a mental image:
“When you first arrive at Fairyland Point in the mouth of Bryce Canyon National Park, you’re met by a singular sight,” Gleiner writes on www.countrywalker.com. “Mounting up from the floor of the canyon, row upon row of pink-limestone spires catch the afternoon sunlight. Each has a drippy, organic look — more like a half-melted candle than a weathered rock formation. You’d be forgiven for imagining that they were made by an enormous cement mixer run amok. These features are called ‘hoodoos,’ and they were eons in the making.”
They can range in height from a few feet to a 15-story building. Because of their mystical nature, they are often called “hoodoos” after the African-American folk spirituality similar to that found in Jamaica, Haiti and New Orleans. But here’s the best part: Instead of your everyday rock spires and pinnacles that are relatively smooth and simply taper from the ground up, hoodoos, because of their makeup, have variable thicknesses, resulting in fantastical shapes. As they do with clouds, people see all kinds of figures in them, resulting in such names as The Rabbit, ET, Thor’s Hammer and the Three Wise Men.
According to the Park Service, their origin dates back 30 to 40 million years ago when a massive ancient lake covered much of western Utah. In this lake, sedimentary rock built up, forming what’s often called the Paunsaugunt Plateau. Once the lake disappeared and through other seismic forces, this plateau became exposed and opened itself to Mother Nature’s carving tools.
Her primary tool is a weathering force called “frost wedging.” Bryce Canyon experiences more than 200 freeze-thaw cycles a years. Even in the Midwest, you know what freeze-thaw cycles can do to roads and bridges: They create potholes. It’s the same thing with the hoodoos. As the Paunsaugunt Plateau became exposed, cracks developed in the rocks. In winter, water from melting snow seeped into these cracks and froze at night, forming an ice wedge. When water freezes, it expands by about 10 percent, which slowly led to bigger cracks. Eventually, pieces of rock of varying sizes began to pop off, creating over the ages the fascinating formations seen today.
But that’s not the whole story. Even the crystal clear air of Bryce Canyon creates slightly acidic rainwater, which slowly can dissolve the rock grain by grain as it falls. It is this process that rounds the edges of the hoodoos and gives them their lumpy, bulging profiles, the Park Service says.
In addition, there are several types of rocks in these hoodoos: the harder dolomite, limestone and siltstone and the softer mudstone. Because each of these break or erode in different ways and at different rates, they can create far more imaginative formations than you’d see with a similar spire made of one type of rock. For example, many of the most durable hoodoos are capped with magnesium-rich dolomite. Because dolomite dissolves far more slowly, it protects the more fragile limestone underneath. The various types of rocks also produce a rainbow of colors, which are further augmented by moisture from rain or snow.
But we should enjoy them while we can. As you might imagine, the same process that created them is also slowly destroying them, perhaps by as much as 2 to 4 feet every century. Eventually, the Bryce hoodoos will be replaced by a V-shaped canyon and steep cliff walls that result from the erosion patterns of flowing water. Meanwhile, if you go to Bryce Canyon (or see similar structures in Turkey, France, Taiwan and other sites), please stay on any official hiking trails. Even walking up to a hoodoo can weaken the clay slopes around it and hasten its demise, the Park Service warns.
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Answer to Sunday’s trivia: Which is colder, the North Pole or the South Pole? No contest. If Santa Claus likes really cold weather, he should move to Antarctica. The average winter temperature at the South Pole is about minus 80, while it’s a relatively balmy minus 30 at the North Pole, according to the Farmers’ Almanac. The lowest temperature ever directly recorded at ground level on Earth was minus 128.6 at Vostok Station in Antartica on July 21, 1983.Why the big difference between the poles? While the North Pole sits at sea level, the South Pole sits at an altitude of 9,000 feet, thus losing the insulating properties of nearby seawater.
Send your questions to Roger Schlueter, Belleville News-Democrat, 120 S. Illinois St., P.O. Box 427, Belleville, IL 62222-0427, firstname.lastname@example.org or call 618-239-2465.