Did wind or water cause this pattern?
View a larger image (270 kB) or learn about other sol 8 images.
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."