Previous studies of resurge sediments in drill cores from several marine-target impact craters indicated a relationship among the sedimentology, the target water depth, and the magnitude of the event. This offers a potentially valuable opportunity to obtain one of these variables if the other two are known. However, the mechanisms controlling the relationship have remained enigmatic. During the cratering process, fragments from the solid target are mixed with the seawater, and, after an initial turbulent phase, they commonly get deposited inside the seafloor crater when it is filled up by the resurging water. We present a mathematical model for the aquatic settling process of the resurge material. The starting hypothesis is that the finer particles mixed with water give rise to a fluid mixture in which the density and viscosity will depend on the relative water-to-solid content. This variation of the mixture’s properties will cause a different settling velocity of the coarser particles, and thus different settling patterns will be observed for craters with different relative target water depths.