New data reveal mature, integrated drainage systems on mars indicative of past precipitation
Brian M. Hynek, Roger M. Phillips September 2003 Geology v 31, p 757-760
This article from Geology uses a combination of Mars Global Surveyor imaging and altimetry data sets to show that many previously mapped, unconnected, low-stream-order segments are part of larger, integrated, mature drainage networks. The authors conclude that this data indicates that precipitation-caused surface run-off may have sculpted large regions of the Martian surface early in its history.
