Apparently there is four times as much of the mineral olivine as there is supposed to be in a certain area of Mars, an area believed to be 3 to 4 billion years old, opening doubt about the presence of water in the Martian past. Olivine weathers very quickly in the presence of water.
Although there’s a new paper on this research appearing in the journal Geology, some of the research seems to be contained in this November 2003 article for Planetary Science Research Discoveries.
[...] ; the new Believer discovery of more dry riverbeds on Mars With that recent olivine story, it felt like the tide was going the other way, but 21 more riverbeds have been a [...]