Stones spheres puzzle geologists
The stone spheres that occur in a formation known as the “Molen Reef,” surrounding the San Rafael Swell may have been brought to the surface by the same asteroid that caused the extermination of dinosaurs. That was a while back: 65 million years.
According to an article by Evan Hansen in “Ancient American” magazine, the asteroid impact in the Pacific Ocean pushed the seafloor under the continental rock, causing it to buckle upward far inland. The underthrust reached into Eastern Utah, forming the San Rafael Swell. As the Swell was lifted, the rock layer containing the spheres, known as concretions, was brought to the surface. The spheres range from baseball-size to more than ten feet in diameter. They are found in the Ferron Cretaceous Sandstone Shelf.
The information was provided by USU Eastern Geology Professor Michelle Fleck. In the article, “Stone Spheres of the American West,” Hansen concedes he has not been able to form a theory on just how the concretions were formed, but he says, “They were clearly formed as mud on a lake bottom.”
According to Wikipedia, a concretion is a hard, compact mass of matter formed by the precipitation of mineral cement within the spaces between particles, and is found in sedimentary rock or soil. They usually form early in the burial history of the sediment before the rest of the sediment is hardened into rock. The mineral cement, or calcite, makes the concretion harder and more resistant to weathering than the host stratum.
The stone spheres of Castle Country are called “Cannonball Concretions.” Just how their spherical shape was formed apparently remains a mystery. Fleck says she hasn’t found a satisfactory explanation, and one science writer said geologists find concretions only slightly less puzzling than the general public.
In one research article in the Journal for Sedimentary Research, E.F. McBride, et. al., conclude that most but not all concretions grow from their center to their edges through the cementation process over a long period of time. The concretions occur in shelf sandstone and have diameters of between one and six meters. They were deposited within the Cretaceous Western Interior Seaway which occupied a subsiding basin developed during the Late Jurassic and Cretaceous as a result of the rising Sevier fold and thrust belt on the west.
Similar but smaller concretions, known as hematite concretions, are also found in Utah. Their diameters range from one-25th of an inch to eight inches or more. They are also called “moqui marbles” or “blueberries,” and are found in Zion and Capitol Reef national parks, Grand Staircase-Escalante national monument, Snow Canyon State Park and in the Moab area. They have also been observed by the Opportunity Rover on Mars.
Concretions have long been regarded as geological curiosities and have been mistakenly interpreted to be dinosaur eggs, animal and plant fossils, extraterrestrial debris or human artifacts.