Explanation:
Why isn't this sand round?
The robotic
Spirit rover currently rolling across
Mars has found
notably angular sand
in the Columbia Hills on Mars.
Previously, small bits of sand found in the plains of
Gusev Crater were significantly
more round.
The finding indicates that angular hill
sand
has tumbled less and likely traveled a shorter distance than the
corresponding round plain sand.
Such tumbling has the general effect of making sand and rocks
increasingly round and with fewer sharp edges.
Pictured above, as taken last month, are angular sand grains magnified by Spirit's
Microscopic Imager.
The above frame spans about three centimeters.
