Did wind or water cause this pattern?

Scientists found an enticing rock containing a pattern that poses a scientific puzzle. This rock, named "Pipestone," shows a pattern of layering geologists call "cross-bedding." Cross-bedding occurs when wind or water moves sand and other small particles from one place to another and they settle in place. Depending on the environment, the layers can form in slanted, curving patterns as seen in Pipestone (identified by the arrow in this picture).

"This cross-bedding texture can form by either wind or water. If formed by wind, the rock could be part of an ancient sand dune. If formed in water, the rock could be a remnant of a larger rock mass that formed near the shore line of an ancient ocean," explains Ron Greeley, a science team member who is a professor of geology at Arizona State University.

Science team studies cross-bedding

In order to solve the puzzle of whether wind or rain caused these angles in the rock, scientists and engineers will need to move the rover closer to this rock (or a rock similar to it) so that better pictures can be taken to see the size of material that makes up the rock.

"If the cross-bedding includes fragments that are the size of gravel or larger, then it probably formed in water, " says Ron Greeley. "On the other hand, if the cross-bedding is made of sand grains and they are all well-rounded like tiny balls or BBs with a dull surface, then it is more likely that the grains were deposited by the wind."