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We report here results of a culture-independent technique analysis of bacterial diversity in a rock desert varnish coating from Death Valley, California. DNA was extracted from varnish coatings, and using PCR to amplify 16SrRNA, both Archaea and Bacteria rRNA were amplified from coatings and surrounding soils. Clone libraries of bacterial- and archaeal-specific PCR product from desert varnish were then constructed and phylogenetic analyses, using full-length sequences, were done. This study indicates that there are a wide variety of prokaryotic microorganism in varnish coatings including non-thermophilic crenarchaeota, and possibly autophototrophic primary producers. If DNA from recent or ancient microbes is ever found on Mars, then understanding the mechanisms for preservation of DNA in extreme Earth environments is essential.