APXS_Meridiani1: The energy range of 2.0 keV to 13.0 keV of the X-ray
spectra measured at Tamaruc and McKittrick (post-RAT) are plotted
here. Intensities are shown on a logarithmic scale to cover the large
range in concentrations. This part of the energy spectrum clearly
shows the high elemental concentrations of sulfur and bromine in the
McKittrick rock, compared to the Tamaruc soil.  A rock named Guadalupe
also has extremely high concentrations of sulfur, but very little
bromine.  This "element fractionation" is typical of what happens when
a watery brine slowly evaporates and various salt compounds are
precipitated in sequence as they are no longer soluble in the
diminishing water supply.