Primordial Atmosphere (IMAGE) Brown University Caption Mars may have been enveloped in a thick, steamy atmosphere as the planet's crust cooled and solidified. That steam bath could have created many of the clay mineral deposits that have long been attributed to water flow on or just beneath the surface. Credit Kevin Cannon Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.