Early Mars and Early earth

I will talk about some comparative aspects of the evolution of Mars and Earth. Today, the surface of Mars appears dry and lifeless, and the atmospheric composition is defined by chemical processes.
In contrast, the Earth's atmosphere has evolved to one heavily influenced by life with a substantial level of biologically-produced O2. Pictures from NASA's Mars Global Surveyor (MGS) spacecraft show cross-sections of the ancient Martian crust layered with rocks of different colors. MGS's thermal emission spectrometer has detected areas of sedimentary rock similar to "iron formations" that formed in the Earth's Precambrian oceans (3.8-2.5 billion years ago). How these rocks formed on Mars could have implications for the early Martian atmosphere and the possibility of life.