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Astronomy Picture of the Day
Layered Hills in Arabia Terra on Mars
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zorg.ch
#112723
by
[z]Barbara Harris
@
16.08.2010 00:00
- nach oben -
Layered Hills in Arabia Terra on Mars
Explanation: Why are some hills on
Mars
so layered? The answer is still under investigation. Clearly,
dark windblown sand
surrounds outcropping of light
sedimentary rock
across the floor of crater
Arabia Terra
. The
light rock
clearly appears structured into many
layers
, the lowest of which is likely very old. Although the
dark sand forms dunes
, rippled dunes of lighter colored sand are easier to see surrounding the stepped
mesas
.
Blown sand
possibly
itself eroded
once-larger mesas into the
layered hills
. Most of the
layered shelves
are wide enough to drive a
truck
around. The
above image
, showing an area about 3 kilometers across, was taken in 2003 October by the now defunct
Mars Global Surveyor spacecraft
orbiting
Mars
.
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