The Jurassic Todilto Formation of NW New Mexico and SW Colorado, USA, has utility as an analog of Martian flood evaporites. The Todilto Formation is a concentrically and vertically zoned carbonate (calcite with minor late dolomite) to sulfate (gypsum) evaporite deposit that developed over a short time span (10 4 –10 5 yr) after rapid flooding of the vast dune field of the Entrada Formation. Within the limits of the very different hydrogeologic environments of Mars and Earth, the Todilto setting of short-lived brine evolution in a largely eolian environment, with terminal formation of a salt hydrate common to both planets (gypsum), provides a useful field area for descriptive and petrogenetic studies of evaporite evolution and interaction with a porous, sandy substrate. The Todilto Formation has an added feature of interest in its association with bituminous materials that have likely microbial precursors, providing a brine-microorganism association that may represent a potential setting for primitive life as might be found on Mars.