I ran into a link from a NASA page over to an Astrobiology webzine. In the article it referenced "sedimentary rock" on Mars. I don't really care about all the other claims of this article, some rather fantastic claims frankly. Rather I am interested in the use of the phrase sedimentary rock. Have we established that martian sedimentary rock, and by that inferred its formation, is equivalent to what we commonly call sedimentary, and if so how much of observed martian rock would be classed as sedimentary ? I'm interested in finding where martian rock formations are discussed in any substantial way..... Thanks.