Scientists and geologists at a university in northern Czech Republic have uncovered the mystery of how natural sandstone monuments such as those at Arches National Park in Utah form.
Using experiments in laboratories, scientists have confirmed that gravity, wind, water, and other natural forces shape sandstone into stunning monuments by slowly eroding sandstone with the least pressure.
The Arches National Park
The Arches National Park in Utah features more than 2000 giant arches made out of sandstone. These sandstone arches are believed to have formed over millions of years. It was declared a national park on November 12, 1971, and many tourists are still attracted to it.
Arches National Park has the most colorful sandstones including the salmon-colored Entrada Sandstone, and Navajo sandstone. Although these arches may look durable and rugged, they are very fragile. Scientists predict that all of these arches were huge blocks of sand that were eroded over time by wind and rain. Some of the main arches are Delicate Arch, Double O Arch, and The Devil’s Garden.
How The Monuments Formed
Scientists have been trying to understand how the sandstone arches formed. This has been difficult because the monuments take millions of years to form. Recently, scientists have created experiments in which the arches formed within a few minutes!
In these experiments, scientists took blocks of soft sandstone from a quarry in Czech Republic. They immersed these blocks under water. Pressure plates on top of the sandstone rocks simulated the weight of material above. At the beginning, this block experienced a certain pressure.
Within minutes, the sandstone on the edges started washing away, leaving smaller blocks of smaller sandstone to bear the weight. As the blocks became smaller, no further erosion was seen. The sandstone walls that remain experience more pressure (see Side Notes) as they have to bear the weight. This pressure is called compression stress. Scientists theorize that this leads the sandstone grains to interlock and become very hard, preventing further erosion.
In this amazing process of sandstone formation, scientists have called gravity the sculptor of the monuments, and the forces of nature such as flowing water or wind its tools.