A marine sedimentary model for the evolution of the northern plains

For the purpose of focusing the following discussion, we begin with the reasonable assumption that landforms interpreted to be shorelines can be considered to be as diagnostic of former water levels within the northern plains of Mars as lava flows are of former volcanism. Once (or if) this interpretation of these features becomes more generally accepted and the compositional and topographic datasets for Mars improve, their distribution can be used to make valuable independent estimates of the planet's water budget by providing quantitative measures of surface reservoir volumes at specific instances in Martian history. The problem is approached from a consideration of the basin's volume and its implied requirement on juvenile water sources and channel discharges, rather than the other way around.