Finally the mystery of Sandston shapes revealed.
The beautiful and majestic sandstone arches and pillars that mark areas in Utah and beyond are not a direct reflection of erosion. They are not just a direct result of wind and rain. They are not created atop a layer of concrete – rather there is a medley of tools used in the creation of sandstone landforms. Researchers gathered together to determine how the rustic arches are formed. The study, published in the journal Nature Geoscience, discovered how once the hardened surface of the sandstone was penetrated; it crumbled into a pile of sand. There is a toolbox from nature involved in making these beautiful and alien shapes.
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.
Jiri Bruthans, a hydrogeologist from the Charles University in Prague, worked on the study. He stated erosion, like wind and rain, was just a “tool” used to develop the landforms.
The researchers blasted a sandstone face, and discovered something interesting. While erosion removed the excess “material” from the landform, it did not create it. Rather, it was created by the stress fields from the overlying rock weight. As stress increased, and parts of the pillar eroded away, the sand grains locked together, decreasing the chances of further erosion. Wind and rain helped to smooth away the loose pieces of sediment.
The scientists wanted to know how soft material could continue to build rapidly, even after the blast.
Working with co-author, Alan Mayo, a hydro geologist from the Brigham University in Utah, the team gathered sandstone samples for a lab review. The samples were cut into small cubes and placed under pressurized plates to simulate the impact of the overlying rock weight. The researchers then added elements of simulated rain and natural forces, like erosion.
Sandstone Structures Shaped by Stress and Nature’s Toolbox When these elements collaborated, the once crumbly sand developed into pillars, alcoves and arches, and more radically – they resisted further erosion.
Mayo states the study shows that although erosion should collapse the material, it instead adds to the increasing pressure to lock the sand grains together. The researchers state although the explanation is plausible and the research sound, it is possible not all sandstone formations are created equal.
“Nature is very complex,” Bruthans said.
He added erosion and weather alone should not be credited for the landforms. Rather, stated Bruthans, it was the stress field which provides the shape to the sandstone formations.
In an accompanying comment article for Nature Geoscience, Prof Chris Paola from the university of Minnesota, US, described the discovery as “an exquisite and stylish formative mechanism for a beautiful and elegant more or less landform”.
“These pure sculptures have delighted numerous visitors, some of whom should have paused to marvel the place they arrive from,” Prof Paola wrote. “Here is a solution.”
Researchers Figure out the Secret of Sandstone Shapes
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