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The rover's Pancam
captured this stunning stack of layered rocks,
called "Camelback," which could provide fingerprint-like clues
that help scientists figure out what type of land-moving processes sculpted
this "outcrop." Outcrop is a term geologists use to describe
rock features that were once underground in the past and are presently
exposed because of intense environmental changes caused by wind, rain,
and gravity over thousands of years.
While the rocks exposed here are certainly very old, it's hard to tell
their exact age. Each layer in the rock face, however, represents a
different time period in history. Because there are so many layers, it's
clear that this feature has been around for a while. As science team
member Jack Farmer relates, "We may not know the age, but
what we can say is that these layers of rock accumulated over time as
one horizontal layer was deposited on top of another. The fact that the
rocks are gently tilted to the right show that they were later lifted up by
some geologic process in the area."
Jack is a professor of Geological Sciences at Arizona State University
who has been interested in geology for his whole career. Since he won't
be able to study landforms on Mars personally, sending a rover to study a
rock like this one is the next best thing. That's because the rover has to
get really up-close and personal with the outcrop to understand the
history of the region through its rock layers.
A primary goal of the science team today is to test the hypothesis
(that is, a possible explanation) that the rocks in this image were
formed by water. Testing for ancient water at this site will be
accomplished through a combination of instruments, such as
which can tell the science team a lot about
the composition of the rocks --that is, what minerals they are made of.
This compositional information will be crucial for identifying the presence of
water-formed minerals, such as carbonates.
Scientists will compare the compositional information for each rock
layer with close-up images of these areas and microscopic images of other
pieces of rock that have fallen down from higher layers on the outcrop to
places where the rover can safely traverse. "The combination of this
information about the different layers should allow us to decide whether
there is any evidence of water here at any time," says Farmer.
How will the science team do that? Each layer is the proverbial
"product of its environment." As Jack explains, "As
each layer was laid down, it captured a record of the climate and
environment that existed locally at the time the rocks were formed. The
layers at the bottom were laid down first, and those at the top, last. By
looking at each layer, we can determine whether--and when, relative to
other layers--water was present. We can also tell what form the water
was in--that is, whether a stream, a lake, or an ocean was responsible for
creating the various minerals in the layers."