What's that Bump in the Streambed?
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What's this large outcrop of rock
doing out in the middle of a dry streambed? Researchers were puzzled by
this exposure of rock out in the middle of a
streambed. Large exposures of rocks are common along the edge of the
streambed where the streambed has cut away and removed the rock.
Inside the streambed, rocks and soils should be removed each time water
flows down the river. Yet images returned from the FIDO rover show a few
large exposures of rock within the streambed.
"We were surprised to see such a beautiful exposure of this
geologic unit sitting in the middle of the streambed," said Cathy
Weitz, the Mars Exploration Rover Program Scientist from NASA
Headquarters. "The fact that the rock didn't get eroded by the
water after each flood event tells us that this material is pretty hard. It
also looks like the upper surface of the exposure is harder compared to
the material underneath, which is why more of the underlying material
has been removed."
One possible explanation for the hardened material is from
weathering. Sometimes material can get added from either water or
wind and this can cement and add strength to the original rock or soil.
But it's unlikely that the weathering would occur in such a small area
associated with just this outcrop. Another possibility is that the water
flowing down the streambed got diverted around this particular spot and
that's why it's still left standing as a remnant compared to any adjacent
material. The present shape of the rock is due to weathering and removal
of debris, which eventually will cause all of it to be removed.
"This FIDO test is a great way to practice our science process.
We're all eager to do the real mission on Mars and I have been anxious to
participate for a long time. When I was a graduate student in 1997, the
Pathfinder mission landed on Mars. I knew right then that I wanted to be
involved on a rover mission, and I've focused my career on that goal