Gravity Helped Naturally Create Sandstone Landmark Shapes
By Esther Tanquintic-Misa | July 22, 2014 2:38 PM EST
Sandstone landmark shapes, such as those found in the Arches National Park in eastern Utah, U.S., are products made no less than by Mother Nature itself and not by some medieval or first human settler. Mother Nature's secret? Gravity.
A study published in Nature Geoscience by geologists said the pressure of gravity helped prevent against erosion certain parts of a sandstone rock.
Putting compact cubes of sand under different weight loads and then dipped them in water, researchers watched as the edges of the cube slowly slip away within a few minutes, leaving less grains of the sand to carry the extra weight. As it continued, the stress on the leftover column gradually caused the grains to secure together and withstand further erosion.
"The stress field is the master sculptor - it tells the weather where to pick," Dr Jiri Bruthans from Charles University in Prague, the study's first author, told BBC News.
Ultimately, it's the rock's internal stresses and structure that determine and help create such formations' magnificent shapes.
"To create perfect shapes you do not need intelligence or planning," he said. "The opposite is true for nature. Most perfect things are made by simple mechanisms."
Adding supplemental faults or other disruptions to the cube and altering the manner of application of pressure, researchers were able to reproduce a range of shapes seen in natural formations.
"You can control it completely," Bruthans said. "You select the pillar direction, by choosing the points where you apply the compression."
"It's just the stress which controls the shape - nothing else," he added.
Sandstone arches, alcoves and pillars are scattered across the globe. One of the more famous is the Arches National Park in eastern Utah, U.S., a protected land spanning 76,679 acres and protects over 2,000 arches, such as the Delicate Arch, the Petrified Dunes and the Balanced Rock, among others.
The highest point in the park is Elephant Butte, which is 5,653 feet high. The lowest point is found at the visitor center, at 4,085 feet high.
Prof Chris Paola from the University of Minnesota, U.S. marveled at how researchers were able to answer the question on how these magnificent sandstone shapes came about.
"These natural sculptures have delighted countless visitors, some of whom must have paused to wonder where they come from," Prof Paola said. "Here is an answer."
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