This piece of gypsum crust broken free from the bottom of a saltern evaporation pond in Eliat, Israel, shows marked vertical zonation in the microbial community. The oxygen levels and associated redox potentials at different depths below the surface facilitate the growth of different microorganisms. The photograph was taken in 2007 by a student from the University of Osnabrueck, Germany.


The solar salt ponds at Eliat draw their source water from the Red Sea.